Autophagy sequesters damaged lysosomes to control lysosomal biogenesis and kidney injury

PubMed Central

Maejima, Ikuko; Takahashi, Atsushi; Omori, Hiroko; Kimura, Tomonori; Takabatake, Yoshitsugu; Saitoh, Tatsuya; Yamamoto, Akitsugu; Hamasaki, Maho; Noda, Takeshi; Isaka, Yoshitaka; Yoshimori, Tamotsu

2013-01-01

Diverse causes, including pathogenic invasion or the uptake of mineral crystals such as silica and monosodium urate (MSU), threaten cells with lysosomal rupture, which can lead to oxidative stress, inflammation, and apoptosis or necrosis. Here, we demonstrate that lysosomes are selectively sequestered by autophagy, when damaged by MSU, silica, or the lysosomotropic reagent L-Leucyl-L-leucine methyl ester (LLOMe). Autophagic machinery is recruited only on damaged lysosomes, which are then engulfed by autophagosomes. In an autophagy-dependent manner, low pH and degradation capacity of damaged lysosomes are recovered. Under conditions of lysosomal damage, loss of autophagy causes inhibition of lysosomal biogenesis in vitro and deterioration of acute kidney injury in vivo. Thus, we propose that sequestration of damaged lysosomes by autophagy is indispensable for cellular and tissue homeostasis. PMID:23921551

Autophagy sequesters damaged lysosomes to control lysosomal biogenesis and kidney injury.

PubMed

Maejima, Ikuko; Takahashi, Atsushi; Omori, Hiroko; Kimura, Tomonori; Takabatake, Yoshitsugu; Saitoh, Tatsuya; Yamamoto, Akitsugu; Hamasaki, Maho; Noda, Takeshi; Isaka, Yoshitaka; Yoshimori, Tamotsu

2013-08-28

Diverse causes, including pathogenic invasion or the uptake of mineral crystals such as silica and monosodium urate (MSU), threaten cells with lysosomal rupture, which can lead to oxidative stress, inflammation, and apoptosis or necrosis. Here, we demonstrate that lysosomes are selectively sequestered by autophagy, when damaged by MSU, silica, or the lysosomotropic reagent L-Leucyl-L-leucine methyl ester (LLOMe). Autophagic machinery is recruited only on damaged lysosomes, which are then engulfed by autophagosomes. In an autophagy-dependent manner, low pH and degradation capacity of damaged lysosomes are recovered. Under conditions of lysosomal damage, loss of autophagy causes inhibition of lysosomal biogenesis in vitro and deterioration of acute kidney injury in vivo. Thus, we propose that sequestration of damaged lysosomes by autophagy is indispensable for cellular and tissue homeostasis.

Anatomical and cellular responses of Pinus monticola stem tissues to invasion by Cronartium ribicola

Treesearch

J. W. Hudgins; G. I . McDonald; P. J. Zambino; N. B. Klopfenstein; V. R. Franceschi

2005-01-01

White pine blister rust (Cronartium ribicola) causes extensive damage to white pines and their associated ecosystems across North America. The anatomical and cellular characteristics of C. ribicola colonization in Pinus monticola branch and stem tissues were studied as a basis for understanding host tree reactions that may be related to resistance. Samples examined...

Comparative kinetics of damage to the plasma and mitochondrial membranes by intra-cellularly synthesized and externally-provided photosensitizers using multi-color FACS.

PubMed

Haupt, Sara; Malik, Zvi; Ehrenberg, Benjamin

2014-01-01

Photodynamic therapy (PDT) of cancer involves inflicting lethal damage to the cells of malignant tumors, primarily by singlet oxygen that is generated following light-absorption in a photosensitizer molecule. Dysfunction of cells is manifested in many ways, including peroxidation of cellular components, membrane rupture, depolarization of electric potentials, termination of mitochondrial activity, onset of apoptosis and necrosis and eventually cell lysis. These events do not necessarily occur in linear fashion and different types of damage to cell components occur, most probably, in parallel. In this report we measured the relative rates of damage to two cellular membranes: the plasma membrane and the mitochondrial membrane. We employed photosensitizers of diverse hydrophobicities and used different incubation procedures, which lead to their different intra-cellular localizations. We monitored the damage that was inflicted on these membranes, by employing optical probes of membrane integrity, in a multi-color FACS experiment. The potentiometric indicator JC-1 monitored the electric cross-membrane potential of the mitochondria and the fluorometric indicator Draq7 monitored the rupture of the plasma membrane. We show that the electric depolarization of the mitochondrial membrane and the damage to the enveloping plasma membrane proceed with different kinetics that reflect the molecular character and intracellular location of the sensitizer: PpIX that is synthesized in the cells from ALA causes rapid mitochondrial damage and very slow damage to the plasma membrane, while externally added PpIX has an opposite effect. The hydrophilic sensitizer HypS4 can be taken up by the cells by different incubation conditions, and these affect its intracellular location, and as a consequence either the plasma membrane or the mitochondria is damaged first. A similar correlation was found for additional extracellularly-provided photosensitizers HP and PpIX.

Ablation of XP-V gene causes adipose tissue senescence and metabolic abnormalities

PubMed Central

Chen, Yih-Wen; Harris, Robert A.; Hatahet, Zafer; Chou, Kai-ming

2015-01-01

Obesity and the metabolic syndrome have evolved to be major health issues throughout the world. Whether loss of genome integrity contributes to this epidemic is an open question. DNA polymerase η (pol η), encoded by the xeroderma pigmentosum (XP-V) gene, plays an essential role in preventing cutaneous cancer caused by UV radiation-induced DNA damage. Herein, we demonstrate that pol η deficiency in mice (pol η−/−) causes obesity with visceral fat accumulation, hepatic steatosis, hyperleptinemia, hyperinsulinemia, and glucose intolerance. In comparison to WT mice, adipose tissue from pol η−/− mice exhibits increased DNA damage and a greater DNA damage response, indicated by up-regulation and/or phosphorylation of ataxia telangiectasia mutated (ATM), phosphorylated H2AX (γH2AX), and poly[ADP-ribose] polymerase 1 (PARP-1). Concomitantly, increased cellular senescence in the adipose tissue from pol η−/− mice was observed and measured by up-regulation of senescence markers, including p53, p16Ink4a, p21, senescence-associated (SA) β-gal activity, and SA secretion of proinflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) as early as 4 wk of age. Treatment of pol η−/− mice with a p53 inhibitor, pifithrin-α, reduced adipocyte senescence and attenuated the metabolic abnormalities. Furthermore, elevation of adipocyte DNA damage with a high-fat diet or sodium arsenite exacerbated adipocyte senescence and metabolic abnormalities in pol η−/− mice. In contrast, reduction of adipose DNA damage with N-acetylcysteine or metformin ameliorated cellular senescence and metabolic abnormalities. These studies indicate that elevated DNA damage is a root cause of adipocyte senescence, which plays a determining role in the development of obesity and insulin resistance. PMID:26240351

Magmas functions as a ROS regulator and provides cytoprotection against oxidative stress-mediated damages

PubMed Central

Srivastava, S; Sinha, D; Saha, P P; Marthala, H; D'Silva, P

2014-01-01

Redox imbalance generates multiple cellular damages leading to oxidative stress-mediated pathological conditions such as neurodegenerative diseases and cancer progression. Therefore, maintenance of reactive oxygen species (ROS) homeostasis is most important that involves well-defined antioxidant machinery. In the present study, we have identified for the first time a component of mammalian protein translocation machinery Magmas to perform a critical ROS regulatory function. Magmas overexpression has been reported in highly metabolically active tissues and cancer cells that are prone to oxidative damage. We found that Magmas regulates cellular ROS levels by controlling its production as well as scavenging. Magmas promotes cellular tolerance toward oxidative stress by enhancing antioxidant enzyme activity, thus preventing induction of apoptosis and damage to cellular components. Magmas enhances the activity of electron transport chain (ETC) complexes, causing reduced ROS production. Our results suggest that J-like domain of Magmas is essential for maintenance of redox balance. The function of Magmas as a ROS sensor was found to be independent of its role in protein import. The unique ROS modulatory role of Magmas is highlighted by its ability to increase cell tolerance to oxidative stress even in yeast model organism. The cytoprotective capability of Magmas against oxidative damage makes it an important candidate for future investigation in therapeutics of oxidative stress-related diseases. PMID:25165880

UV-B COMPONENT OF SUNLIGHT CAUSES MEASURABLE DAMAGE IN FIELD-GROWN MAIZE (ZEA MAYS L.): DEVELOPMENTAL AND CELLULAR HETEROGENEITY OF DAMAGE AND REPAIR. (R824900)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Hypertonic stress induces rapid and widespread protein damage in C. elegans

PubMed Central

Burkewitz, Kris; Choe, Keith

2011-01-01

Proteostasis is defined as the homeostatic mechanisms that maintain the function of all cytoplasmic proteins. We recently demonstrated that the capacity of the proteostasis network is a critical factor that defines the limits of cellular and organismal survival in hypertonic environments. The current studies were performed to determine the extent of protein damage induced by cellular water loss. Using worm strains expressing fluorescently tagged foreign and endogenous proteins and proteins with temperature-sensitive point mutations, we demonstrate that hypertonic stress causes aggregation and misfolding of diverse proteins in multiple cell types. Protein damage is rapid. Aggregation of a polyglutamine yellow fluorescent protein reporter is observable with <1 h of hypertonic stress, and aggregate volume doubles approximately every 10 min. Aggregate formation is irreversible and occurs after as little as 10 min of exposure to hypertonic conditions. To determine whether endogenous proteins are aggregated by hypertonic stress, we quantified the relative amount of total cellular protein present in detergent-insoluble extracts. Exposure for 4 h to 400 mM or 500 mM NaCl induced a 55–120% increase in endogenous protein aggregation. Inhibition of insulin signaling or acclimation to mild hypertonic stress increased survival under extreme hypertonic conditions and prevented aggregation of endogenous proteins. Our results demonstrate that hypertonic stress causes widespread and dramatic protein damage and that cells have a significant capacity to remodel the network of proteins that function to maintain proteostasis. These findings have important implications for understanding how cells cope with hypertonic stress and other protein-damaging stressors. PMID:21613604

Macromolecular Expression and Function: A New Paradigm for NASA Risk Assessment

NASA Technical Reports Server (NTRS)

Richmond, Robert

2003-01-01

Predicting risks in humans of either acute effects such as bone loss or muscle wasting, or late effects such as cancer, is challenging. To an approximation, this is because uncertainties of exposure to stress factors or toxic agents and the uniformity of processing subsequent damage at the cellular level within a complex set of biological variables degrade the confidence of predicting pathologic outcome. A cellular biodosimeter that simultaneously reports 1) the type of damage due to that exposure, 2) the quantity of damage incurred by that exposure, and 3) the dataset used to assess risk of developing pathologic outcome caused by that exposure would therefore be useful for predicting ultimate risks faced by an individual, such as an astronaut. It is suggested that such a biodosimeter can be based upon analyses of gene-expression and protein expression whereby large datasets of cellular response to damage are obtained and analyzed for expression-profiles correlated with established end points and molecular markers predictive for risks being assessed. The usefulness of multiparametric cellular biodosimeters could be realized by quantitatively profiling these datasets using techniques of bioinformatics. Such an approach contributes to the foundation of molecular epidemiology as a new scientific discipline, and represents a new paradigm of risk assessment.

Sirtuin 7 promotes cellular survival following genomic stress by attenuation of DNA damage, SAPK activation and p53 response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiran, Shashi; Oddi, Vineesha; Ramakrishna, Gayatri, E-mail: gayatrirama1@gmail.com

2015-02-01

Maintaining the genomic integrity is a constant challenge in proliferating cells. Amongst various proteins involved in this process, Sirtuins play a key role in DNA damage repair mechanisms in yeast as well as mammals. In the present work we report the role of one of the least explored Sirtuin viz., SIRT7, under conditions of genomic stress when treated with doxorubicin. Knockdown of SIRT7 sensitized osteosarcoma (U2OS) cells to DNA damage induced cell death by doxorubicin. SIRT7 overexpression in NIH3T3 delayed cell cycle progression by causing delay in G1 to S transition. SIRT7 overexpressing cells when treated with low dose ofmore » doxorubicin (0.25 µM) showed delayed onset of senescence, lesser accumulation of DNA damage marker γH2AX and lowered levels of growth arrest markers viz., p53 and p21 when compared to doxorubicin treated control GFP expressing cells. Resistance to DNA damage following SIRT7 overexpression was also evident by EdU incorporation studies where cellular growth arrest was significantly delayed. When treated with higher dose of doxorubicin (>1 µM), SIRT7 conferred resistance to apoptosis by attenuating stress activated kinases (SAPK viz., p38 and JNK) and p53 response thereby shifting the cellular fate towards senescence. Interestingly, relocalization of SIRT7 from nucleolus to nucleoplasm together with its co-localization with SAPK was an important feature associated with DNA damage. SIRT7 mediated resistance to doxorubicin induced apoptosis and senescence was lost when p53 level was restored by nutlin treatment. Overall, we propose SIRT7 attenuates DNA damage, SAPK activation and p53 response thereby promoting cellular survival under conditions of genomic stress. - Highlights: • Knockdown of SIRT7 sensitized cells to DNA damage induced apoptosis. • SIRT7 delayed onset of premature senescence by attenuating DNA damage response. • Overexpression of SIRT7 delayed cell cycle progression by delaying G1/S transition. • Upon DNA damage SIRT7 attenuated p38/JNK activation and also p53 response. • Overall, SIRT7 promoted cellular survival in conditions of genomic stress.« less

Deoxyribonucleoprotein structure and radiation injury - Cellular radiosensitivity is determined by LET-infinity-dependent DNA damage in hydrated deoxyribonucleoproteins and the extent of its repair

NASA Technical Reports Server (NTRS)

Lett, J. T.; Peters, E. L.

1992-01-01

Until recently, OH radicals formed in bulk nuclear water were believed to be the major causes of DNA damage that results in cell death, especially for sparsely ionizing radiations. That hypothesis has now been challenged, if not refuted. Lethal genomic DNA damage is determined mainly by energy deposition in deoxyribonucleoproteins, and their hydration shells, and charge (energy) transfer processes within those structures.

SM22{alpha}-induced activation of p16{sup INK4a}/retinoblastoma pathway promotes cellular senescence caused by a subclinical dose of {gamma}-radiation and doxorubicin in HepG2 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tae Rim; Lee, Hee Min; Lee, So Yong

Research highlights: {yields} SM22{alpha} overexpression in HepG2 cells leads cells to a growth arrest state, and the treatment of a subclinical dose of {gamma}-radiation or doxorubicin promotes cellular senescence. {yields} SM22{alpha} overexpression elevates p16{sup INK4a} followed by pRB activation, but there are no effects on p53/p21{sup WAF1/Cip1} pathway. {yields} SM22{alpha}-induced MT-1G activates p16{sup INK4a}/pRB pathway, which promotes cellular senescence by damaging agents. -- Abstract: Smooth muscle protein 22-alpha (SM22{alpha}) is known as a transformation- and shape change-sensitive actin cross-linking protein found in smooth muscle tissue and fibroblasts; however, its functional role remains uncertain. We reported previously that SM22{alpha} overexpression confersmore » resistance against anti-cancer drugs or radiation via induction of metallothionein (MT) isozymes in HepG2 cells. In this study, we demonstrate that SM22{alpha} overexpression leads cells to a growth arrest state and promotes cellular senescence caused by treatment with a subclinical dose of {gamma}-radiation (0.05 and 0.1 Gy) or doxorubicin (0.01 and 0.05 {mu}g/ml), compared to control cells. Senescence growth arrest is known to be controlled by p53 phosphorylation/p21{sup WAF1/Cip1} induction or p16{sup INK4a}/retinoblastoma protein (pRB) activation. SM22{alpha} overexpression in HepG2 cells elevated p16{sup INK4a} followed by pRB activation, but did not activate the p53/p21{sup WAF1/Cip1} pathway. Moreover, MT-1G, which is induced by SM22{alpha} overexpression, was involved in the activation of the p16{sup INK4a}/pRB pathway, which led to a growth arrest state and promoted cellular senescence caused by damaging agents. Our findings provide the first demonstration that SM22{alpha} modulates cellular senescence caused by damaging agents via regulation of the p16{sup INK4a}/pRB pathway in HepG2 cells and that these effects of SM22{alpha} are partially mediated by MT-1G.« less

Phytochemical Ginkgolide B Attenuates Amyloid-β1-42 Induced Oxidative Damage and Altered Cellular Responses in Human Neuroblastoma SH-SY5Y Cells.

PubMed

Gill, Iqbal; Kaur, Sukhchain; Kaur, Navrattan; Dhiman, Monisha; Mantha, Anil K

2017-01-01

Oxidative stress is an upsurge in reactive oxygen/nitrogen species (ROS/RNS), which aggravates damage to cellular components viz. lipids, proteins, and nucleic acids resulting in impaired cellular functions and neurological pathologies including Alzheimer's disease (AD). In the present study, we have examined amyloid-β (Aβ)-induced oxidative stress responses, a major cause for AD, in the undifferentiated and differentiated human neuroblastoma SH-SY5Y cells. Aβ1-42-induced oxidative damage was evaluated on lipids by lipid peroxidation; proteins by protein carbonyls; antioxidant status by SOD and GSH enzyme activities; and DNA and RNA damage levels by evaluating the number of AP sites and 8-OHG base damages produced. In addition, the neuro-protective role of the phytochemical ginkgolide B (GB) in countering Aβ1-42-induced oxidative stress was assessed. We report that the differentiated cells are highly vulnerable to Aβ1-42-induced oxidative stress events as exerted by the deposition of Aβ in AD. Results of the current study suggest that the pre-treatment of GB, followed by Aβ1-42 treatment for 24 h, displayed neuro-protective potential, which countered Aβ1-42-induced oxidative stress responses in both undifferentiated and differentiated SH-SY5Y neuronal cells by: 1) hampering production of ROS and RNS; 2) reducing lipid peroxidation; 3) decreasing protein carbonyl content; 4) restoring antioxidant activities of SOD and GSH enzymes; and 5) maintaining genome integrity by reducing the oxidative DNA and RNA base damages. In conclusion, Aβ1-42 induces oxidative damage to the cellular biomolecules, which are associated with AD pathology, and are protected by the pre-treatment of GB against Aβ-toxicity. Taken together, this study advocates for phytochemical-based therapeutic interventions against AD.

Importance of cell damage causing growth delay for high pressure inactivation of Saccharomyces cerevisiae

NASA Astrophysics Data System (ADS)

Nanba, Masaru; Nomura, Kazuki; Nasuhara, Yusuke; Hayashi, Manabu; Kido, Miyuki; Hayashi, Mayumi; Iguchi, Akinori; Shigematsu, Toru; Hirayama, Masao; Ueno, Shigeaki; Fujii, Tomoyuki

2013-06-01

A high pressure (HP) tolerant (barotolerant) mutant a2568D8 and a variably barotolerant mutant a1210H12 were generated from Saccharomyces cerevisiae using ultra-violet mutagenesis. The two mutants, a barosensitive mutant a924E1 and the wild-type strain, were pressurized (225 MPa), and pressure inactivation behavior was analyzed. In the wild-type strain, a proportion of the growth-delayed cells were detected after exposure to HP. In a924E1, the proportion of growth-delayed cells significantly decreased compared with the wild-type. In a2568D8, the proportion of growth-delayed cells increased and the proportion of inactivated cells decreased compared with the wild-type. In a1210H12, the growth-delayed cells could not be detected within 120 s of exposure to HP. The proportion of growth-delayed cells, which incurred the damage, would affect the survival ratio by HP. These results suggested that cellular changes in barotolerance caused by mutations are remarkably affected by the ability to recover from cellular damage, which results in a growth delay.

Protective role of integrin-linked kinase against oxidative stress and in maintenance of genomic integrity

PubMed Central

Im, Michelle; Dagnino, Lina

2018-01-01

The balance between the production of reactive oxygen species and activation of antioxidant pathways is essential to maintain a normal redox state in all tissues. Oxidative stress caused by excessive oxidant species generation can cause damage to DNA and other macromolecules, affecting cell function and viability. Here we show that integrin-linked kinase (ILK) plays a key role in eliciting a protective response to oxidative damage in epidermal cells. Inactivation of the Ilk gene causes elevated levels of intracellular oxidant species (IOS) and DNA damage in the absence of exogenous oxidative insults. In ILK-deficient cells, excessive IOS production can be prevented through inhibition of NADPH oxidase activity, with a concomitant reduction in DNA damage. Additionally, ILK is necessary for DNA repair processes following UVB-induced damage, as ILK-deficient cells show a significantly impaired ability to remove cyclobutane pyrimidine dimers following irradiation. Thus, ILK is essential to maintain cellular redox balance and, in its absence, epidermal cells become more susceptible to oxidative damage through mechanisms that involve IOS production by NADPH oxidase activity. PMID:29568383

Protective role of integrin-linked kinase against oxidative stress and in maintenance of genomic integrity.

PubMed

Im, Michelle; Dagnino, Lina

2018-03-02

The balance between the production of reactive oxygen species and activation of antioxidant pathways is essential to maintain a normal redox state in all tissues. Oxidative stress caused by excessive oxidant species generation can cause damage to DNA and other macromolecules, affecting cell function and viability. Here we show that integrin-linked kinase (ILK) plays a key role in eliciting a protective response to oxidative damage in epidermal cells. Inactivation of the Ilk gene causes elevated levels of intracellular oxidant species (IOS) and DNA damage in the absence of exogenous oxidative insults. In ILK-deficient cells, excessive IOS production can be prevented through inhibition of NADPH oxidase activity, with a concomitant reduction in DNA damage. Additionally, ILK is necessary for DNA repair processes following UVB-induced damage, as ILK-deficient cells show a significantly impaired ability to remove cyclobutane pyrimidine dimers following irradiation. Thus, ILK is essential to maintain cellular redox balance and, in its absence, epidermal cells become more susceptible to oxidative damage through mechanisms that involve IOS production by NADPH oxidase activity.

Adenovirus Core Protein VII Downregulates the DNA Damage Response on the Host Genome

PubMed Central

Avgousti, Daphne C.; Della Fera, Ashley N.; Otter, Clayton J.; Herrmann, Christin; Pancholi, Neha J.

2017-01-01

ABSTRACT Viral manipulation of cellular proteins allows viruses to suppress host defenses and generate infectious progeny. Due to the linear double-stranded DNA nature of the adenovirus genome, the cellular DNA damage response (DDR) is considered a barrier to successful infection. The adenovirus genome is packaged with protein VII, a virally encoded histone-like core protein that is suggested to protect incoming viral genomes from detection by the cellular DNA damage machinery. We showed that protein VII localizes to host chromatin during infection, leading us to hypothesize that protein VII may affect DNA damage responses on the cellular genome. Here we show that protein VII at cellular chromatin results in a significant decrease in accumulation of phosphorylated H2AX (γH2AX) following irradiation, indicating that protein VII inhibits DDR signaling. The oncoprotein SET was recently suggested to modulate the DDR by affecting access of repair proteins to chromatin. Since protein VII binds SET, we investigated a role for SET in DDR inhibition by protein VII. We show that knockdown of SET partially rescues the protein VII-induced decrease in γH2AX accumulation on the host genome, suggesting that SET is required for inhibition. Finally, we show that knockdown of SET also allows ATM to localize to incoming viral genomes bound by protein VII during infection with a mutant lacking early region E4. Together, our data suggest that the protein VII-SET interaction contributes to DDR evasion by adenovirus. Our results provide an additional example of a strategy used by adenovirus to abrogate the host DDR and show how viruses can modify cellular processes through manipulation of host chromatin. IMPORTANCE The DNA damage response (DDR) is a cellular network that is crucial for maintaining genome integrity. DNA viruses replicating in the nucleus challenge the resident genome and must overcome cellular responses, including the DDR. Adenoviruses are prevalent human pathogens that can cause a multitude of diseases, such as respiratory infections and conjunctivitis. Here we describe how a small adenovirus core protein that localizes to host chromatin during infection can globally downregulate the DDR. Our study focuses on key players in the damage signaling pathway and highlights how viral manipulation of chromatin may influence access of DDR proteins to the host genome. PMID:28794020

Sam68 Is Required for DNA Damage Responses via Regulating Poly(ADP-ribosyl)ation

PubMed Central

Hodgson, Andrea; Wier, Eric M.; Wen, Matthew G.; Kamenyeva, Olena; Xia, Xue; Koo, Lily Y.

2016-01-01

The rapid and robust synthesis of polymers of adenosine diphosphate (ADP)-ribose (PAR) chains, primarily catalyzed by poly(ADP-ribose) polymerase 1 (PARP1), is crucial for cellular responses to DNA damage. However, the precise mechanisms through which PARP1 is activated and PAR is robustly synthesized are not fully understood. Here, we identified Src-associated substrate during mitosis of 68 kDa (Sam68) as a novel signaling molecule in DNA damage responses (DDRs). In the absence of Sam68, DNA damage-triggered PAR production and PAR-dependent DNA repair signaling were dramatically diminished. With serial cellular and biochemical assays, we demonstrated that Sam68 is recruited to and significantly overlaps with PARP1 at DNA lesions and that the interaction between Sam68 and PARP1 is crucial for DNA damage-initiated and PARP1-conferred PAR production. Utilizing cell lines and knockout mice, we illustrated that Sam68-deleted cells and animals are hypersensitive to genotoxicity caused by DNA-damaging agents. Together, our findings suggest that Sam68 plays a crucial role in DDR via regulating DNA damage-initiated PAR production. PMID:27635653

Cellular mechanisms of noise-induced hearing loss.

PubMed

Kurabi, Arwa; Keithley, Elizabeth M; Housley, Gary D; Ryan, Allen F; Wong, Ann C-Y

2017-06-01

Exposure to intense sound or noise can result in purely temporary threshold shift (TTS), or leave a residual permanent threshold shift (PTS) along with alterations in growth functions of auditory nerve output. Recent research has revealed a number of mechanisms that contribute to noise-induced hearing loss (NIHL). The principle cause of NIHL is damage to cochlear hair cells and associated synaptopathy. Contributions to TTS include reversible damage to hair cell (HC) stereocilia or synapses, while moderate TTS reflects protective purinergic hearing adaptation. PTS represents permanent damage to or loss of HCs and synapses. While the substrates of HC damage are complex, they include the accumulation of reactive oxygen species and the active stimulation of intracellular stress pathways, leading to programmed and/or necrotic cell death. Permanent damage to cochlear neurons can also contribute to the effects of NIHL, in addition to HC damage. These mechanisms have translational potential for pharmacological intervention and provide multiple opportunities to prevent HC damage or to rescue HCs and spiral ganglion neurons that have suffered injury. This paper reviews advances in our understanding of cellular mechanisms that contribute to NIHL and their potential for therapeutic manipulation. Published by Elsevier B.V.

Cytotoxicity and DNA cleavage with core-shell nanocomposites functionalized by a KH domain DNA binding peptide

NASA Astrophysics Data System (ADS)

Bazak, Remon; Ressl, Jan; Raha, Sumita; Doty, Caroline; Liu, William; Wanzer, Beau; Salam, Seddik Abdel; Elwany, Samy; Paunesku, Tatjana; Woloschak, Gayle E.

2013-11-01

A nanoconjugate was composed of metal oxide nanoparticles decorated with peptides and fluorescent dye and tested for DNA cleavage following UV light activation. The peptide design was based on a DNA binding domain, the so called KH domain of the hnRNPK protein. This ``KH peptide'' enabled cellular uptake of nanoconjugates and their entry into cell nuclei. The control nanoconjugate carried no peptide; it consisted only of the metal oxide nanoparticle prepared as Fe3O4@TiO2 nanocomposite and the fluorescent dye alizarin red S. These components of either construct are responsible for nanoconjugate activation by UV light and the resultant production of reactive oxygen species (ROS). Production of ROS at different subcellular locations causes damage to different components of cells: only nanoconjugates inside cell nuclei can be expected to cause DNA cleavage. Degradation of cellular DNA with KH peptide decorated nanoconjugates exceeded the DNA damage obtained from control, no-peptide nanoconjugate counterparts. Moreover, caspase activation and cell death were more extensive in the same cells.A nanoconjugate was composed of metal oxide nanoparticles decorated with peptides and fluorescent dye and tested for DNA cleavage following UV light activation. The peptide design was based on a DNA binding domain, the so called KH domain of the hnRNPK protein. This ``KH peptide'' enabled cellular uptake of nanoconjugates and their entry into cell nuclei. The control nanoconjugate carried no peptide; it consisted only of the metal oxide nanoparticle prepared as Fe3O4@TiO2 nanocomposite and the fluorescent dye alizarin red S. These components of either construct are responsible for nanoconjugate activation by UV light and the resultant production of reactive oxygen species (ROS). Production of ROS at different subcellular locations causes damage to different components of cells: only nanoconjugates inside cell nuclei can be expected to cause DNA cleavage. Degradation of cellular DNA with KH peptide decorated nanoconjugates exceeded the DNA damage obtained from control, no-peptide nanoconjugate counterparts. Moreover, caspase activation and cell death were more extensive in the same cells. Electronic supplementary information (ESI) available: http://janus.northwestern.edu/wololab/auxiliary/supplementary_data_2013.docx. See DOI: 10.1039/c3nr02203j

Regulation of replicative senescence by NADP+ -dependent isocitrate dehydrogenase.

PubMed

Kil, In Sup; Huh, Tae Lin; Lee, Young Sup; Lee, You Mie; Park, Jeen-Woo

2006-01-01

The free radical hypothesis of aging postulates that senescence is due to an accumulation of cellular oxidative damage, caused largely by reactive oxygen species that are produced as by-products of normal metabolic processes. Recently, we demonstrated that the control of cytosolic and mitochondrial redox balance and the cellular defense against oxidative damage is one of the primary functions of cytosolic (IDPc) and mitochondrial NADP+ -dependent isocitrate dehydrogenase (IDPm) by supplying NADPH for antioxidant systems. In this paper, we demonstrate that modulation of IDPc or IDPm activity in IMR-90 cells regulates cellular redox status and replicative senescence. When we examined the regulatory role of IDPc and IDPm against the aging process with IMR-90 cells transfected with cDNA for IDPc or IDPm in sense and antisense orientations, a clear inverse relationship was observed between the amount of IDPc or IDPm expressed in target cells and their susceptibility to senescence, which was reflected by changes in replicative potential, cell cycle, senescence-associated beta-galactosidase activity, expression of p21 and p53, and morphology of cells. Furthermore, lipid peroxidation, oxidative DNA damage, and intracellular peroxide generation were higher and cellular redox status shifted to a prooxidant condition in the cell lines expressing the lower level of IDPc or IDPm. The results suggest that IDPc and IDPm play an important regulatory role in cellular defense against oxidative stress and in the senescence of IMR-90 cells.

Oxidative Stress and Heart Failure in Altered Thyroid States

PubMed Central

Mishra, Pallavi; Samanta, Luna

2012-01-01

Increased or reduced action of thyroid hormone on certain molecular pathways in the heart and vasculature causes relevant cardiovascular derangements. It is well established that hyperthyroidism induces a hyperdynamic cardiovascular state, which is associated with a faster heart rate, enhanced left ventricular systolic and diastolic function whereas hypothyroidism is characterized by the opposite changes. Hyperthyroidism and hypothyroidism represent opposite clinical conditions, albeit not mirror images. Recent experimental and clinical studies have suggested the involvement of ROS tissue damage under altered thyroid status. Altered-thyroid state-linked changes in heart modify their susceptibility to oxidants and the extent of the oxidative damage they suffer following oxidative challenge. Chronic increase in the cellular levels of ROS can lead to a catastrophic cycle of DNA damage, mitochondrial dysfunction, further ROS generation and cellular injury. Thus, these cellular events might play an important role in the development and progression of myocardial remodeling and heart failure in altered thyroid states (hypo- and hyper-thyroidism). The present review aims at elucidating the various signaling pathways mediated via ROS and their modulation under altered thyroid state and the possibility of antioxidant therapy. PMID:22649319

Atmospheric skin aging-Contributors and inhibitors.

PubMed

McDaniel, David; Farris, Patricia; Valacchi, Giuseppe

2018-04-01

Cutaneous aging is a complex biological process consisting of 2 elements: intrinsic aging, which is primarily determined by genetics, and extrinsic aging, which is largely caused by atmospheric factors, such as exposure to sunlight and air pollution, and lifestyle choices, such as diet and smoking. The role of the solar spectrum, comprised of ultraviolet light, specifically UVB (290-320 nm) and UVA (320-400) in causing skin damage, including skin cancers, has been well documented. In recent years, the contribution of visible light (400-700 nm) and infrared radiation (above 800 nm) in causing skin damage, similar to the photodamage caused by UV light, is also being elucidated. In addition, other atmospheric factors such as air pollution (smog, ozone, particulate matter, etc.) have been implicated in premature skin aging. The skin damage caused by environmental exposure is largely attributable to a complex cascade of reactions inside the skin initiated by the generation of reactive oxygen species (ROS), which causes oxidative damage to cellular components such as proteins, lipids, and nucleic acids. These damaged skin cells initiate inflammatory responses leading to the eventual damage manifested in chronically exposed skin. Novel therapeutic strategies to combat ROS species generation are being developed to prevent the skin damage caused by atmospheric factors. In addition to protecting skin from solar radiation using sunscreens, other approaches using topically applied ingredients, particularly antioxidants that penetrate the skin and protect the skin from within, have also been well documented. This review summarizes current knowledge of atmospheric aggressors, including UVA, UVB, visible light, infrared radiation (IR), and ozone on skin damage, and proposes new avenues for future research in the prevention and treatment of premature skin aging caused by such atmospheric factors. New therapeutic modalities currently being developed are also discussed. © 2018 Wiley Periodicals, Inc.

Mechanisms of DNA Damage Response to Targeted Irradiation in Organotypic 3D Skin Cultures

PubMed Central

Acheva, Anna; Ghita, Mihaela; Patel, Gaurang; Prise, Kevin M.; Schettino, Giuseppe

2014-01-01

DNA damage (caused by direct cellular exposure and bystander signaling) and the complex pathways involved in its repair are critical events underpinning cellular and tissue response following radiation exposures. There are limited data addressing the dynamics of DNA damage induction and repair in the skin particularly in areas not directly exposed. Here we investigate the mechanisms regulating DNA damage, repair, intracellular signalling and their impact on premature differentiation and development of inflammatory-like response in the irradiated and surrounding areas of a 3D organotypic skin model. Following localized low-LET irradiation (225 kVp X-rays), low levels of 53BP1 foci were observed in the 3D model (3.8±0.28 foci/Gy/cell) with foci persisting and increasing in size up to 48 h post irradiation. In contrast, in cell monolayers 14.2±0.6 foci/Gy/cell and biphasic repair kinetics with repair completed before 24 h was observed. These differences are linked to differences in cellular status with variable level of p21 driving apoptotic signalling in 2D and accelerated differentiation in both the directly irradiated and bystander areas of the 3D model. The signalling pathways utilized by irradiated keratinocytes to induce DNA damage in non-exposed areas of the skin involved the NF-κB transcription factor and its downstream target COX-2. PMID:24505255

Detection of vulnerable neurons damaged by environmental insults in utero

PubMed Central

Torii, Masaaki; Chang, Yu-Wen; Ishii, Seiji; Waxman, Stephen G.; Kocsis, Jeffery D.; Rakic, Pasko; Hashimoto-Torii, Kazue

2017-01-01

Development of prognostic biomarkers for the detection of prenatally damaged neurons before manifestations of postnatal disorders is an essential step for prevention and treatment of susceptible individuals. We have developed a versatile fluorescence reporter system in mice enabling detection of Heat Shock Factor 1 activation in response to prenatal cellular damage caused by exposure to various harmful chemical or physical agents. Using an intrautero electroporation-mediated reporter assay and transgenic reporter mice, we are able to identify neurons that survive prenatal exposure to harmful agents but remain vulnerable in postnatal life. This system may provide a powerful tool for exploring the pathogenesis and treatment of multiple disorders caused by exposure to environmental stress before symptoms become manifested, exacerbated, and/or irreversible. PMID:28123061

DNA damage and repair in plants under ultraviolet and ionizing radiations.

PubMed

Gill, Sarvajeet S; Anjum, Naser A; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315-400 nm; UV-B, 280-315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH(•)) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context.

Developmental consequences of cryopreservation of mammalian oocytes and embryos.

PubMed

Smith, Gary D; Silva E Silva, Cristine Ane

2004-08-01

During the last three decades, significant advances have been made in successful cryopreservation of mammalian preimplantation embryos, and more recently oocytes. The ability to cryopreserve, thaw, and establish pregnancies with supernumerary preimplantation embryos has become an important tool in fertility treatment. Human oocyte cryopreservation has practical application in preserving fertility for individuals at risk of compromised egg quality due to cancer treatments or advanced maternal age. While oocyte/embryo cryopreservation success has increased over time, there is still room for improvement. Oocytes and embryos are susceptible to cryo-damage, which collectively entails cellular damage caused by mechanical, chemical, or thermal forces during the freeze-thaw process. Basic studies focused on understanding cellular structures, their composition, and more importantly their functions, in normal cell developments will continue to be critical in assessing, understanding, and correcting oocyte/embryo cryo-damage. This review will delineate many of the oocyte/embryo intracellular and extracellular structures that are or may be compromised during cryopreservation. A global theme presented throughout this review is that many structural components of the oocyte/embryo also have essential functional roles in development. Compromising these cellular structures, and thus their cellular homeostatic functions, can deleteriously influence initial cryo-survival or compromise subsequent normal development through effects on the oocyte and/or early embryo.

Protective effect of acetyl-L-carnitine on propofol-induced toxicity in embryonic neural stem cells.

PubMed

Liu, Fang; Rainosek, Shuo W; Sadovova, Natalya; Fogle, Charles M; Patterson, Tucker A; Hanig, Joseph P; Paule, Merle G; Slikker, William; Wang, Cheng

2014-05-01

Propofol is a widely used general anesthetic. A growing body of data suggests that perinatal exposure to general anesthetics can result in long-term deleterious effects on brain function. In the developing brain there is evidence that general anesthetics can cause cell death, synaptic remodeling, and altered brain cell morphology. Acetyl-L-carnitine (L-Ca), an anti-oxidant dietary supplement, has been reported to prevent neuronal damage from a variety of causes. To evaluate the ability of L-Ca to protect against propofol-induced neuronal toxicity, neural stem cells were isolated from gestational day 14 rat fetuses and on the eighth day in culture were exposed for 24h to propofol at 10, 50, 100, 300 and 600 μM, with or without L-Ca (10 μM). Markers of cellular proliferation, mitochondrial health, cell death/damage and oxidative damage were monitored to determine: (1) the effects of propofol on neural stem cell proliferation; (2) the nature of propofol-induced neurotoxicity; (3) the degree of protection afforded by L-Ca; and (4) to provide information regarding possible mechanisms underlying protection. After propofol exposure at a clinically relevant concentration (50 μM), the number of dividing cells was significantly decreased, oxidative DNA damage was increased and a significant dose-dependent reduction in mitochondrial function/health was observed. No significant effect on lactase dehydrogenase (LDH) release was observed at propofol concentrations up to 100 μM. The oxidative damage at 50 μM propofol was blocked by L-Ca. Thus, clinically relevant concentrations of propofol induce dose-dependent adverse effects on rat embryonic neural stem cells by slowing or stopping cell division/proliferation and causing cellular damage. Elevated levels of 8-oxoguanine suggest enhanced oxidative damage [reactive oxygen species (ROS) generation] and L-Ca effectively blocks at least some of the toxicity of propofol, presumably by scavenging oxidative species and/or reducing their production. Published by Elsevier B.V.

Probing the cellular damage in bacteria induced by GaN nanoparticles using confocal laser Raman spectroscopy

NASA Astrophysics Data System (ADS)

Sahoo, Prasana; Murthy, P. Sriyutha; Dhara, S.; Venugopalan, V. P.; Das, A.; Tyagi, A. K.

2013-08-01

Understanding the mechanism of nanoparticle (NP) induced toxicity in microbes is of potential importance to a variety of disciplines including disease diagnostics, biomedical implants, and environmental analysis. In this context, toxicity to bacterial cells and inhibition of biofilm formation by GaN NPs and their functional derivatives have been investigated against gram positive and gram negative bacterial species down to single cellular level. High levels of inhibition of biofilm formation (>80 %) was observed on treatments with GaN NPs at sub-micro molar concentrations. These results were substantiated with morphological features investigated with field emission scanning electron microscope, and the observed changes in vibrational modes of microbial cells using Raman spectroscopy. Raman spectra provided molecular interpretation of cell damage by registering signatures of molecular vibrations of individual living microbial cells and mapping the interplay of proteins at the cell membrane. As compared to the untreated cells, Raman spectra of NP-treated cells showed an increase in the intensities of characteristic protein bands, which confirmed membrane damage and subsequent release of cellular contents outside the cells. Raman spectral mapping at single cellular level can facilitate understanding of the mechanistic aspect of toxicity of GaN NPs. The effect may be correlated to passive diffusion causing mechanical damage to the membrane or ingress of Ga3+ (ionic radius 0.076 nm) which can potentially interfere with bacterial metabolism, as it resembles Fe2+ (ionic radius 0.077 nm), which is essential for energy metabolism.

Balancing repair and tolerance of DNA damage caused by alkylating agents.

PubMed

Fu, Dragony; Calvo, Jennifer A; Samson, Leona D

2012-01-12

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for a favourable response of an organism to alkylating agents. Furthermore, the response of an individual to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity.

SERIES: Genomic instability in cancer Balancing repair and tolerance of DNA damage caused by alkylating agents

PubMed Central

Fu, Dragony; Calvo, Jennifer A.; Samson, Leona D

2013-01-01

Alkylating agents comprise a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER), and mismatch repair (MMR) respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for an organism's favorable response to alkylating agents. Furthermore, an individual's response to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity. PMID:22237395

A senescence secretory switch mediated by PI3K/AKT/mTOR activation controls chemoprotective endothelial secretory responses

PubMed Central

Bent, Eric H.; Gilbert, Luke A.; Hemann, Michael T.

2016-01-01

Cancer therapy targets malignant cells that are surrounded by a diverse complement of nonmalignant stromal cells. Therapy-induced damage of normal cells can alter the tumor microenvironment, causing cellular senescence and activating cancer-promoting inflammation. However, how these damage responses are regulated (both induced and resolved) to preserve tissue homeostasis and prevent chronic inflammation is poorly understood. Here, we detail an acute chemotherapy-induced secretory response that is self-limiting in vitro and in vivo despite the induction of cellular senescence. We used tissue-specific knockout mice to demonstrate that endothelial production of the proinflammatory cytokine IL-6 promotes chemoresistance and show that the chemotherapeutic doxorubicin induces acute IL-6 release through reactive oxygen species-mediated p38 activation in vitro. Doxorubicin causes endothelial senescence but, surprisingly, without a typical senescence secretory response. We found that endothelial cells repress senescence-associated inflammation through the down-regulation of PI3K/AKT/mTOR signaling and that reactivation of this pathway restores senescence-associated inflammation. Thus, we describe a mechanism by which damage-associated paracrine secretory responses are restrained to preserve tissue homeostasis and prevent chronic inflammation. PMID:27566778

Polyamines and abiotic stress in plants: a complex relationship1

PubMed Central

Minocha, Rakesh; Majumdar, Rajtilak; Minocha, Subhash C.

2014-01-01

The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress. PMID:24847338

Enantioselective oxidative stress and oxidative damage caused by Rac- and S-metolachlor to Scenedesmus obliquus.

PubMed

Liu, Huijun; Xia, YiLu; Cai, Weidan; Zhang, Yina; Zhang, Xiaoqiang; Du, Shaoting

2017-04-01

The rational use and environmental security of chiral pesticides has gained the interest of many researchers. The enantioselective effects of Rac- and S-metolachlor on oxidative stress in Scenedesmus obliquus were determined in this study. Stronger green fluorescence was observed in response to S-metolachlor treatment than to Rac-metolachlor treatment, suggesting that more reactive oxygen species (ROS) were stimulated by S-metolachlor. ROS levels following S-metolachlor treatment were 1.92-, 8.31-, and 1.08-times higher than those observed following Rac-metolachlor treatment at 0.1, 0.2, and 0.3 mg/L, respectively. Superoxide dismutase (SOD) and catalase (CAT) were stimulated with increasing herbicide concentrations, with S-metolachlor exhibiting a greater effect. Oxidative damage in terms of chlorophyll (Chl) content, cellular membrane permeability, and cellular ultrastructures of S. obliquus were investigated. Chla and Chlb contents in algae treated with Rac-metolachlor were 2-6-fold higher than those in algae treated with S-metolachlor at 0.1, 0.2, and 0.3 mg/L. The cellular membrane permeability of algae exposed to 0.3 mg/L Rac- and S-metolachlor was 6.19- and 42.5-times that of the control. Correlation analysis implied that ROS are the major factor responsible for the oxidative damage caused by Rac- and S-metolachlor. Damage to the chloroplasts and cell membrane of S. obliquus, low production of starch granules, and an increased number of vacuoles were observed upon ultrastructural morphology analysis by transmission electron microscope. These results indicate that S-metolachlor has a greater effect on S. obliquus than Rac-metolachlor. Copyright © 2017 Elsevier Ltd. All rights reserved.

2016 Arte Poster Competition First Place Winner: Circadian Rhythm and UV-Induced Skin Damage: An In Vivo Study.

PubMed

Guan, Linna; Suggs, Amanda; Ahsanuddin, Sayeeda; Tarrillion, Madeline; Selph, Jacqueline; Lam, Minh; Baron, Elma

2016-09-01

Exposure of the skin to ultraviolet (UV) irradiation causes many detrimental effects through mechanisms related to oxidative stress and DNA damage. Excessive oxidative stress can cause apoptosis and cellular dysfunction of epidermal cells leading to cellular senescence and connective tissue degradation. Direct and indirect damage to DNA predisposes the skin to cancer formation. Chronic UV exposure also leads to skin aging manifested as wrinkling, loss of skin tone, and decreased resilience. Fortunately, human skin has several natural mechanisms for combating UV-induced damage. The mechanisms operate on a diurnal rhythm, a cycle that repeats approximately every 24 hours. It is known that the circadian rhythm is involved in many skin physiologic processes, including water regulation and epidermal stem cell function. This study evaluated whether UV damage and the skin's natural mechanisms of inflammation and repair are also affected by circadian rhythm. We looked at UV-induced erythema on seven human subjects irradiated with simulated solar radiation in the morning (at 08:00 h) versus in the afternoon (at 16:00 h). Our data suggest that the same dose of UV radiation induces significantly more inflammation in the morning than in the afternoon. Changes in protein expression relevant to DNA damage, such as xeroderma pigmentosum, complementation group A (XPA), and cyclobutane pyrimidine dimers (CPD) from skin biopsies correlated with our clinical results. Both XPA and CPD levels were higher after the morning UV exposure compared with the afternoon exposure.

J Drugs Dermatol. 2016;15(9):1124-1130.

Multiparametric Determination of Radiation Risk

NASA Technical Reports Server (NTRS)

Richmond, Robert C.

2003-01-01

Predicting risk of human cancer following exposure to ionizing space radiation is challenging in part because of uncertainties of low-dose distribution amongst cells, of unknown potentially synergistic effects of microgravity upon cellular protein-expression, and of processing dose-related damage within cells to produce rare and late-appearing malignant transformation, degrade the confidence of cancer risk-estimates. The NASA- specific responsibility to estimate the risks of radiogenic cancer in a limited number of astronauts is not amenable to epidemiologic study, thereby increasing this challenge. Developing adequately sensitive cellular biodosimeters that simultaneously report 1) the quantity of absorbed close after exposure to ionizing radiation, 2) the quality of radiation delivering that dose, and 3) the risk of developing malignant transformation by the cells absorbing that dose could be useful for resolving these challenges. Use of a multiparametric cellular biodosimeter is suggested using analyses of gene-expression and protein-expression whereby large datasets of cellular response to radiation-induced damage are obtained and analyzed for expression-profiles correlated with established end points and molecular markers predictive for cancer-risk. Analytical techniques of genomics and proteomics may be used to establish dose-dependency of multiple gene- and protein- expressions resulting from radiation-induced cellular damage. Furthermore, gene- and protein-expression from cells in microgravity are known to be altered relative to cells grown on the ground at 1g. Therefore, hypotheses are proposed that 1) macromolecular expression caused by radiation-induced damage in cells in microgravity may be different than on the ground, and 2) different patterns of macromolecular expression in microgravity may alter human radiogenic cancer risk relative to radiation exposure on Earth. A new paradigm is accordingly suggested as a national database wherein genomic and proteomic datasets are registered and interrogated in order to provide statistically significant dose-dependent risk estimation of radiogenic cancer in astronauts.

Involvement of lysosomal dysfunction in silver nanoparticle-induced cellular damage in A549 human lung alveolar epithelial cells.

PubMed

Miyayama, Takamitsu; Matsuoka, Masato

2016-01-01

While silver nanoparticles (AgNPs) are widely used in consumer and medical products, the mechanism by which AgNPs cause pulmonary cytotoxicity is not clear. AgNP agglomerates are found in endo-lysosomal structures within the cytoplasm of treated cells. In this study, the functional role of lysosomes in AgNP-induced cellular damage was examined in A549 human lung alveolar epithelial cells. We evaluated the intracellular distribution of AgNPs, lysosomal pH, cellular viability, Ag dissolution, and metallothionein (MT) mRNA levels in AgNP-exposed A549 cells that were treated with bafilomycin A1, the lysosomal acidification inhibitor. Exposure of A549 cells to citrate-coated AgNPs (20 nm diameter) for 24 h induced cellular damage and cell death at 100 and 200 μg Ag/ml, respectively. Confocal laser microscopic examination of LysoTracker-stained cells showed that AgNPs colocalized with lysosomes and their agglomeration increased in a dose-dependent manner (50-200 μg Ag/ml). In addition, the fluorescence signals of LysoTracker were reduced following exposure to AgNPs, suggesting the elevation of lysosomal pH. Treatment of A549 cells with 200 nM bafilomycin A1 and AgNPs (50 μg Ag/ml) further reduced the fluorescence signals of LysoTracker. AgNP-induced cell death was also increased by bafilomycin A1 treatment. Finally, treatment with bafilomycin A1 suppressed the dissolution of Ag and decreased the mRNA expression levels of MT-I and MT-II following exposure to AgNPs. The perturbation of lysosomal pH by AgNP exposure may play a role in AgNP agglomeration and subsequent cellular damage in A549 cells.

Ripk3 regulates cardiac microvascular reperfusion injury: The role of IP3R-dependent calcium overload, XO-mediated oxidative stress and F-action/filopodia-based cellular migration.

PubMed

Zhou, Hao; Wang, Jin; Zhu, Pingjun; Hu, Shunying; Ren, Jun

2018-05-01

Ripk3-mediated cellular apoptosis is a major contributor to the pathogenesis of myocardial ischemia reperfusion (IR) injury. However, the mechanisms by which Ripk3 influences microvascular homeostasis and endothelial apoptosis are not completely understood. In this study, loss of Ripk3 inhibited endothelial apoptosis, alleviated luminal swelling, maintained microvasculature patency, reduced the expression of adhesion molecules and limited the myocardial inflammatory response. In vitro, Ripk3 deficiency protected endothelial cells from apoptosis and migratory arrest induced by HR injury. Mechanistically, Ripk3 had the ability to migrate onto the endoplasmic reticulum (ER), leading to ER damage, as evidenced by increased IP3R and XO expression. The higher IP3R content was associated with cellular calcium overload, and increased XO expression was involved in cellular oxidative injury. Furthermore, IP3R-mediated calcium overload and XO-dependent oxidative damage were able to initiate cellular apoptosis. More importantly, IP3R and XO also caused F-actin degradation into G-actin via post-transcriptional modification of cofilin, impairing the formation of the filopodia and limiting the migratory response of endothelial cells. Altogether, our data confirmed that Ripk3 was involved in microvascular IR injury via regulation of IP3R-mediated calcium overload, XO-dependent oxidative damage and filopodia-related cellular migration, ultimately leading to endothelial apoptosis and migratory inhibition. These findings provide a potential target for treating cardiac microcirculatory IR injury. Copyright © 2018 Elsevier Inc. All rights reserved.

Dropping macadamia nuts-in-shell reduces kernel roasting quality.

PubMed

Walton, David A; Wallace, Helen M

2010-10-01

Macadamia nuts ('nuts-in-shell') are subjected to many impacts from dropping during postharvest handling, resulting in damage to the raw kernel. The effect of dropping on roasted kernel quality is unknown. Macadamia nuts-in-shell were dropped in various combinations of moisture content, number of drops and receiving surface in three experiments. After dropping, samples from each treatment and undropped controls were dry oven-roasted for 20 min at 130 °C, and kernels were assessed for colour, mottled colour and surface damage. Dropping nuts-in-shell onto a bed of nuts-in-shell at 3% moisture content or 20% moisture content increased the percentage of dark roasted kernels. Kernels from nuts dropped first at 20%, then 10% moisture content, onto a metal plate had increased mottled colour. Dropping nuts-in-shell at 3% moisture content onto nuts-in-shell significantly increased surface damage. Similarly, surface damage increased for kernels dropped onto a metal plate at 20%, then at 10% moisture content. Postharvest dropping of macadamia nuts-in-shell causes concealed cellular damage to kernels, the effects not evident until roasting. This damage provides the reagents needed for non-enzymatic browning reactions. Improvements in handling, such as reducing the number of drops and improving handling equipment, will reduce cellular damage and after-roast darkening. Copyright © 2010 Society of Chemical Industry.

Ascorbate attenuates pulmonary emphysema by inhibiting tobacco smoke and Rtp801-triggered lung protein modification and proteolysis.

PubMed

Gupta, Indranil; Ganguly, Souradipta; Rozanas, Christine R; Stuehr, Dennis J; Panda, Koustubh

2016-07-19

Cigarette smoking causes emphysema, a fatal disease involving extensive structural and functional damage of the lung. Using a guinea pig model and human lung cells, we show that oxidant(s) present in tobacco smoke not only cause direct oxidative damage of lung proteins, contributing to the major share of lung injury, but also activate Rtp801, a key proinflammatory cellular factor involved in tobacco smoke-induced lung damage. Rtp801 triggers nuclear factor κB and consequent inducible NOS (iNOS)-mediated overproduction of NO, which in combination with excess superoxide produced during Rtp801 activation, contribute to increased oxido-nitrosative stress and lung protein nitration. However, lung-specific inhibition of iNOS with a iNOS-specific inhibitor, N6-(1-iminoethyl)-L-lysine, dihydrochloride (L-NIL) solely restricts lung protein nitration but fails to prevent or reverse the major tobacco smoke-induced oxidative lung injury. In comparison, the dietary antioxidant, ascorbate or vitamin C, can substantially prevent such damage by inhibiting both tobacco smoke-induced lung protein oxidation as well as activation of pulmonary Rtp801 and consequent iNOS/NO-induced nitration of lung proteins, that otherwise lead to increased proteolysis of such oxidized or nitrated proteins by endogenous lung proteases, resulting in emphysematous lung damage. Vitamin C also restricts the up-regulation of matrix-metalloproteinase-9, the major lung protease involved in the proteolysis of such modified lung proteins during tobacco smoke-induced emphysema. Overall, our findings implicate tobacco-smoke oxidant(s) as the primary etiopathogenic factor behind both the noncellular and cellular damage mechanisms governing emphysematous lung injury and demonstrate the potential of vitamin C to accomplish holistic prevention of such damage.

Ascorbate attenuates pulmonary emphysema by inhibiting tobacco smoke and Rtp801-triggered lung protein modification and proteolysis

PubMed Central

Gupta, Indranil; Ganguly, Souradipta; Rozanas, Christine R.; Stuehr, Dennis J.

2016-01-01

Cigarette smoking causes emphysema, a fatal disease involving extensive structural and functional damage of the lung. Using a guinea pig model and human lung cells, we show that oxidant(s) present in tobacco smoke not only cause direct oxidative damage of lung proteins, contributing to the major share of lung injury, but also activate Rtp801, a key proinflammatory cellular factor involved in tobacco smoke-induced lung damage. Rtp801 triggers nuclear factor κB and consequent inducible NOS (iNOS)-mediated overproduction of NO, which in combination with excess superoxide produced during Rtp801 activation, contribute to increased oxido-nitrosative stress and lung protein nitration. However, lung-specific inhibition of iNOS with a iNOS-specific inhibitor, N6-(1-iminoethyl)-L-lysine, dihydrochloride (L-NIL) solely restricts lung protein nitration but fails to prevent or reverse the major tobacco smoke-induced oxidative lung injury. In comparison, the dietary antioxidant, ascorbate or vitamin C, can substantially prevent such damage by inhibiting both tobacco smoke-induced lung protein oxidation as well as activation of pulmonary Rtp801 and consequent iNOS/NO-induced nitration of lung proteins, that otherwise lead to increased proteolysis of such oxidized or nitrated proteins by endogenous lung proteases, resulting in emphysematous lung damage. Vitamin C also restricts the up-regulation of matrix-metalloproteinase-9, the major lung protease involved in the proteolysis of such modified lung proteins during tobacco smoke-induced emphysema. Overall, our findings implicate tobacco-smoke oxidant(s) as the primary etiopathogenic factor behind both the noncellular and cellular damage mechanisms governing emphysematous lung injury and demonstrate the potential of vitamin C to accomplish holistic prevention of such damage. PMID:27382160

Sub-cellular damage by copper in the cnidarian Zoanthus robustus.

PubMed

Grant, A; Trompf, K; Seung, D; Nivison-Smith, L; Bowcock, H; Kresse, H; Holmes, S; Radford, J; Morrow, P

2010-09-01

Sessile organisms may experience chronic exposure to copper that is released into the marine environment from antifoulants and stormwater runoff. We have identified the site of damage caused by copper to the symbiotic cnidarian, Zoanthus robustus (Anthozoa, Hexacorallia). External changes to the zoanthids were apparent when compared with controls. The normally flexible bodies contracted and became rigid. Histological examination of the zoanthid tissue revealed that copper had caused sub-cellular changes to proteins within the extracellular matrix (ECM) of the tubular body. Collagen in the ECM and the internal septa increased in thickness to five and seven times that of controls respectively. The epithelium, which stained for elastin, was also twice as thick and tough to cut, but exposure to copper did not change the total amount of desmosine which is found only in elastin. We conclude that copper stimulated collagen synthesis in the ECM and also caused cross-linking of existing proteins. However, there was no expulsion of the symbiotic algae (Symbiodinium sp.) and no effect on algal pigments or respiration (44, 66 and 110 microg Cu L(-1)). A decrease in net photosynthesis was observed only at the highest copper concentration (156 microg Cu L(-1)). These results show that cnidarians may be more susceptible to damage by copper than their symbiotic algae. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Perspectives for the treatment of sensorineural hearing loss by cellular regeneration of the inner ear.

PubMed

Almeida-Branco, Mario S; Cabrera, Sonia; Lopez-Escamez, Jose A

2015-01-01

Sensorineural hearing loss is a caused by the loss of the cochlear hair cells with the consequent deafferentation of spiral ganglion neurons. Humans do not show endogenous cellular regeneration in the inner ear and there is no exogenous therapy that allows the replacement of the damaged hair cells. Currently, treatment is based on the use of hearing aids and cochlear implants that present different outcomes, some difficulties in auditory discrimination and a limited useful life. More advanced technology is hindered by the functional capacity of the remaining spiral ganglion neurons. The latest advances with stem cell therapy and cellular reprogramming have developed several possibilities to induce endogenous regeneration or stem cell transplantation to replace damaged inner ear hair cells and restore hearing function. With further knowledge of the cellular and molecular biology of the inner ear and its embryonic development, it will be possible to use induced stem cells as in vitro models of disease and as replacement cellular therapy. Investigation in this area is focused on generating cellular therapy with clinical use for the treatment of profound sensorineural hearing loss. Copyright © 2014 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

Evaluation of Toxic Effects of Aeration and Trichloroethylene Oxidation on Methanotrophic Bacteria Grown with Different Nitrogen Sources

PubMed Central

Chu, Kung-Hui; Alvarez-Cohen, Lisa

1999-01-01

In this study we evaluated specific and nonspecific toxic effects of aeration and trichloroethylene (TCE) oxidation on methanotrophic bacteria grown with different nitrogen sources (nitrate, ammonia, and molecular nitrogen). The specific toxic effects, exerted directly on soluble methane monooxygenase (sMMO), were evaluated by comparing changes in methane uptake rates and naphthalene oxidation rates following aeration and/or TCE oxidation. Nonspecific toxic effects, defined as general cellular damage, were examined by using a combination of epifluorescent cellular stains to measure viable cell numbers based on respiratory activity and measuring formate oxidation activities following aeration and TCE transformation. Our results suggest that aeration damages predominantly sMMO rather than other general cellular components, whereas TCE oxidation exerts a broad range of toxic effects that damage both specific and nonspecific cellular functions. TCE oxidation caused sMMO-catalyzed activity and respiratory activity to decrease linearly with the amount of substrate degraded. Severe TCE oxidation toxicity resulted in total cessation of the methane, naphthalene, and formate oxidation activities and a 95% decrease in the respiratory activity of methanotrophs. The failure of cells to recover even after 7 days of incubation with methane suggests that cellular recovery following severe TCE product toxicity is not always possible. Our evidence suggests that generation of greater amounts of sMMO per cell due to nitrogen fixation may be responsible for enhanced TCE oxidation activities of nitrogen-fixing methanotrophs rather than enzymatic protection mechanisms associated with the nitrogenase enzymes. PMID:9925614

Candida albicans-Induced Epithelial Damage Mediates Translocation through Intestinal Barriers

PubMed Central

2018-01-01

ABSTRACT Life-threatening systemic infections often occur due to the translocation of pathogens across the gut barrier and into the bloodstream. While the microbial and host mechanisms permitting bacterial gut translocation are well characterized, these mechanisms are still unclear for fungal pathogens such as Candida albicans, a leading cause of nosocomial fungal bloodstream infections. In this study, we dissected the cellular mechanisms of translocation of C. albicans across intestinal epithelia in vitro and identified fungal genes associated with this process. We show that fungal translocation is a dynamic process initiated by invasion and followed by cellular damage and loss of epithelial integrity. A screen of >2,000 C. albicans deletion mutants identified genes required for cellular damage of and translocation across enterocytes. Correlation analysis suggests that hypha formation, barrier damage above a minimum threshold level, and a decreased epithelial integrity are required for efficient fungal translocation. Translocation occurs predominantly via a transcellular route, which is associated with fungus-induced necrotic epithelial damage, but not apoptotic cell death. The cytolytic peptide toxin of C. albicans, candidalysin, was found to be essential for damage of enterocytes and was a key factor in subsequent fungal translocation, suggesting that transcellular translocation of C. albicans through intestinal layers is mediated by candidalysin. However, fungal invasion and low-level translocation can also occur via non-transcellular routes in a candidalysin-independent manner. This is the first study showing translocation of a human-pathogenic fungus across the intestinal barrier being mediated by a peptide toxin. PMID:29871918

DNA Damage Observed in Unaffected Individuals with Family History of T2DM

NASA Astrophysics Data System (ADS)

Ramesh, Nikhila; Abilash, V. G.

2017-11-01

Diabetes has been documented to cause high levels of DNA fragmentation in some cases. As diabetes is inheritable and influenced by both genetic and environmental factors, an investigation into the genomic stability of individuals who are strongly at risk of inheriting diabetes was conducted by inducing oxidative stress, as DNA damage in unaffected individuals could be a sign of onset of the disease or the presence of genetic alterations that reduce cellular defences against reactive oxygen species. In this study, alkaline comet assay was performed on isolated human leukocytes to determine whether individuals with a family history of Type 2 Diabetes Mellitus (T2DM) are more prone to DNA damage under oxidative stress. Visual scoring of comets showed that these individuals have higher degree of DNA damage compared to a control individual with no family history of Type 2 Diabetes Mellitus. Further studies with large sample could determine the presence of disabled cellular defences against oxidative stress in unaffected individuals and intervention with antioxidants could prevent or manage Type 2 Diabetes Mellitus and its complications.

Mechanisms of sulfur mustard analog 2-chloroethyl ethyl sulfide-induced DNA damage in skin epidermal cells and fibroblasts.

PubMed

Inturi, Swetha; Tewari-Singh, Neera; Gu, Mallikarjuna; Shrotriya, Sangeeta; Gomez, Joe; Agarwal, Chapla; White, Carl W; Agarwal, Rajesh

2011-12-15

Employing mouse skin epidermal JB6 cells and dermal fibroblasts, here we examined the mechanisms of DNA damage by 2-chloroethyl ethyl sulfide (CEES), a monofunctional analog of sulfur mustard (SM). CEES exposure caused H2A.X and p53 phosphorylation as well as p53 accumulation in both cell types, starting at 1h, that was sustained for 24h, indicating a DNA-damaging effect of CEES, which was also confirmed and quantified by alkaline comet assay. CEES exposure also induced oxidative stress and oxidative DNA damage in both cell types, measured by an increase in mitochondrial and cellular reactive oxygen species and 8-hydroxydeoxyguanosine levels, respectively. In the studies distinguishing between oxidative and direct DNA damage, 1h pretreatment with glutathione (GSH) or the antioxidant Trolox showed a decrease in CEES-induced oxidative stress and oxidative DNA damage. However, only GSH pretreatment decreased CEES-induced total DNA damage measured by comet assay, H2A.X and p53 phosphorylation, and total p53 levels. This was possibly due to the formation of GSH-CEES conjugates detected by LC-MS analysis. Together, our results show that CEES causes both direct and oxidative DNA damage, suggesting that to rescue SM-caused skin injuries, pleiotropic agents (or cocktails) are needed that could target multiple pathways of mustard skin toxicities. Copyright © 2011 Elsevier Inc. All rights reserved.

Multiphoton microscopy can visualize zonal damage and decreased cellular metabolic activity in hepatic ischemia-reperfusion injury in rats

NASA Astrophysics Data System (ADS)

Thorling, Camilla A.; Liu, Xin; Burczynski, Frank J.; Fletcher, Linda M.; Gobe, Glenda C.; Roberts, Michael S.

2011-11-01

Ischemia-reperfusion (I/R) injury is a common occurrence in liver surgery. In orthotopic transplantation, the donor liver is exposed to periods of ischemia and when oxygenated blood is reintroduced to the liver, oxidative stress may develop and lead to graft failure. The aim of this project was to investigate whether noninvasive multiphoton and fluorescence lifetime imaging microscopy, without external markers, were useful in detecting early liver damage caused by I/R injury. Localized hepatic ischemia was induced in rats for 1 h followed by 4 h reperfusion. Multiphoton and fluorescence lifetime imaging microscopy was conducted prior to ischemia and up to 4 h of reperfusion and compared to morphological and biochemical assessment of liver damage. Liver function was significantly impaired at 2 and 4 h of reperfusion. Multiphoton microscopy detected liver damage at 1 h of reperfusion, manifested by vacuolated cells and heterogeneous spread of damage over the liver. The damage was mainly localized in the midzonal region of the liver acinus. In addition, fluorescence lifetime imaging showed a decrease in cellular metabolic activity. Multiphoton and fluorescence lifetime imaging microscopy detected evidence of early I/R injury both structurally and functionally. This provides a simple noninvasive technique useful for following progressive liver injury without external markers.

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

PubMed Central

Gill, Sarvajeet S.; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315–400 nm; UV-B, 280–315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH•) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context. PMID:25729769

Neuroimaging of Lipid Storage Disorders

ERIC Educational Resources Information Center

Rieger, Deborah; Auerbach, Sarah; Robinson, Paul; Gropman, Andrea

2013-01-01

Lipid storage diseases, also known as the lipidoses, are a group of inherited metabolic disorders in which there is lipid accumulation in various cell types, including the central nervous system, because of the deficiency of a variety of enzymes. Over time, excessive storage can cause permanent cellular and tissue damage. The brain is particularly…

Greater heritability of photosynthesis in maize grown under elevated ozone

USDA-ARS?s Scientific Manuscript database

Tropospheric ozone (O3) pollution is estimated to reduce maize yields up to 10% in the US. O3 causes damage to cellular processes by forming reactive oxygen species that lead to reductions in photosynthetic capacity, accelerated leaf senescence, and ultimately a decrease in reproductive and economic...

Dietary and plant polyphenols exert neuroprotective effects and improve cognitive function in cerebral ischemia

USDA-ARS?s Scientific Manuscript database

Cerebral ischemia is caused by an interruption of blood flow to the brain which generally leads to irreversible brain damage. Ischemic injury is associated with vascular leakage, inflammation, tissue injury, and cell death. Cellular changes associated with ischemia include impairment of metabolism, ...

Protective effect of an intrinsic antioxidant, HMH (5-hydroxy-1-methylhydantoin; NZ-419), against cellular damage of kidney tubules.

PubMed

Ienaga, Kazuharu; Park, Chan Hum; Yokozawa, Takako

2013-07-01

HMH (5-hydroxy-1-methylhydantoin; NZ-419) is a mammalian creatinine metabolite and an intrinsic antioxidant. HMH prevents the progression of chronic kidney disease in rats when a sufficient amount is taken orally. We assessed whether intrinsic and higher levels of HMH could protect tubular epithelial cells, LLC-PK(1) cells, against known cellular damage caused by xenobiotics, such as cisplatin and cephaloridine, or by hypoxia/reoxygenation treatment. Both cell damage and peroxidation, monitored as the leakage of lactate dehydrogenase (LDH) and malondialdehyde (MDA), respectively, from cells into the media, were inhibited by HMH in a concentration-dependent manner. The minimum effective concentration of HMH (2.5 μM) seemed to be too low for HMH to only be a direct hydroxyl radical scavenger. Additional antioxidant effect(s) inhibiting reactive oxygen species generation and/or modulating signal transduction pathways were suggested. The possibility that intrinsic HMH could be a protectant for the kidney was indicated. At the same time, for sufficient inhibition, higher concentrations than intrinsic HMH concentrations may be necessary. Patterns of efficacies of HMH on LDH and MDA against different kinds of cellular damage were compared with our reported data on those of corresponding, naturally occurring antioxidants. A common and specific inhibitory mechanism as well as common target(s) in kidney injuries were indicated. Copyright © 2012 Elsevier GmbH. All rights reserved.

Restriction Endonucleases from Invasive Neisseria gonorrhoeae Cause Double-Strand Breaks and Distort Mitosis in Epithelial Cells during Infection

PubMed Central

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies. PMID:25460012

Restriction endonucleases from invasive Neisseria gonorrhoeae cause double-strand breaks and distort mitosis in epithelial cells during infection.

PubMed

Weyler, Linda; Engelbrecht, Mattias; Mata Forsberg, Manuel; Brehwens, Karl; Vare, Daniel; Vielfort, Katarina; Wojcik, Andrzej; Aro, Helena

2014-01-01

The host epithelium is both a barrier against, and the target for microbial infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae infections disrupt host cell cycle regulation machinery and the infection causes DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release restriction endonucleases that enter the nucleus and damage human chromosomal DNA. Bacterial lysates containing restriction endonucleases were able to fragment genomic DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20 h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and chromosomal instability. These data highlight basic molecular functions of how gonococcal infections affect host cell cycle regulation, cause DNA double strand breaks and predispose cellular malignancies.

Developing Master Keys to Brain Pathology, Cancer and Aging from the Structural Biology of Proteins Controlling Reactive Oxygen Species and DNA Repair

PubMed Central

Perry, J. Jefferson P.; Fan, Li; Tainer, John A.

2007-01-01

This review is focused on proteins with key roles in pathways controlling either reactive oxygen species or DNA damage responses, both of which are essential for preserving the nervous system. An imbalance of reactive oxygen species or inappropriate DNA damage response likely causes mutational or cytotoxic outcomes, which may lead to cancer and/or aging phenotypes. Moreover, individuals with hereditary disorders in proteins of these cellular pathways have significant neurological abnormalities. Mutations in a superoxide dismutase, which removes oxygen free radicals, may cause the neurodegenerative disease amyotrophic lateral sclerosis. Additionally, DNA repair disorders that affect the brain to varying extents include ataxia-telangiectasia-like disorder, Cockayne syndrome or Werner syndrome. Here, we highlight recent advances gained through structural biochemistry studies on enzymes linked to these disorders and other related enzymes acting within the same cellular pathways. We describe the current understanding of how these vital proteins coordinate chemical steps and integrate cellular signaling and response events. Significantly, these structural studies may provide a set of master keys to developing a unified understanding of the survival mechanisms utilized after insults by reactive oxygen species and genotoxic agents, and also provide a basis for developing an informed intervention in brain tumor and neurodegenerative disease progression. PMID:17174478

Poly(GR) in C9ORF72-Related ALS/FTD Compromises Mitochondrial Function and Increases Oxidative Stress and DNA Damage in iPSC-Derived Motor Neurons.

PubMed

Lopez-Gonzalez, Rodrigo; Lu, Yubing; Gendron, Tania F; Karydas, Anna; Tran, Helene; Yang, Dejun; Petrucelli, Leonard; Miller, Bruce L; Almeida, Sandra; Gao, Fen-Biao

2016-10-19

GGGGCC repeat expansions in C9ORF72 are the most common genetic cause of both ALS and FTD. To uncover underlying pathogenic mechanisms, we found that DNA damage was greater, in an age-dependent manner, in motor neurons differentiated from iPSCs of multiple C9ORF72 patients than control neurons. Ectopic expression of the dipeptide repeat (DPR) protein (GR) 80 in iPSC-derived control neurons increased DNA damage, suggesting poly(GR) contributes to DNA damage in aged C9ORF72 neurons. Oxidative stress was also increased in C9ORF72 neurons in an age-dependent manner. Pharmacological or genetic reduction of oxidative stress partially rescued DNA damage in C9ORF72 neurons and control neurons expressing (GR) 80 or (GR) 80 -induced cellular toxicity in flies. Moreover, interactome analysis revealed that (GR) 80 preferentially bound to mitochondrial ribosomal proteins and caused mitochondrial dysfunction. Thus, poly(GR) in C9ORF72 neurons compromises mitochondrial function and causes DNA damage in part by increasing oxidative stress, revealing another pathogenic mechanism in C9ORF72-related ALS and FTD. Copyright © 2016 Elsevier Inc. All rights reserved.

Vitamin E protects against the mitochondrial damage caused by cyclosporin A in LLC-PK1 cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arriba, G. de; Seccion de Nefrologia del Hospital Universitario de Guadalajara; Departamento de Medicina de la Universidad de Alcala de Henares

Cyclosporin A (CsA) has nephrotoxic effects known to involve reactive oxygen species (ROS), since antioxidants prevent the kidney damage induced by this drug. Given that mitochondria are among the main sources of intracellular ROS, the aims of our study were to examine the mitochondrial effects of CsA in the porcine renal endothelial cell line LLC-PK1 and the influence of the antioxidant Vitamin E (Vit E). Following the treatment of LLC-PK1 cells with CsA, we assessed the mitochondrial synthesis of superoxide anion, permeability transition pore opening, mitochondrial membrane potential, cardiolipin peroxidation, cytochrome c release and cellular apoptosis, using flow cytometry andmore » confocal microscopy procedures. Similar experiments were done after Vit E preincubation of cells. CsA treatment increased superoxide anion in a dose-dependent way. CsA opened the permeability transition pores, caused Bax migration to mitochondria, and decreased mitochondrial membrane potential and cardiolipin content. Also CsA released cytochrome c into cytosol and provoked cellular apoptosis. Vit E pretreatment inhibited the effects that CsA induced on mitochondrial structure and function in LLC-PK1 cells and avoided apoptosis. CsA modifies mitochondrial LLC-PK1 cell physiology with loss of negative electrochemical gradient across the inner mitochondrial membrane and increased lipid peroxidation. These features are related to apoptosis and can explain the cellular damage that CsA induces. As Vit E inhibited these effects, our results suggest that they were mediated by an increase in ROS production by mitochondria.« less

Role of ROS and RNS Sources in Physiological and Pathological Conditions

PubMed Central

Victor, Victor Manuel

2016-01-01

There is significant evidence that, in living systems, free radicals and other reactive oxygen and nitrogen species play a double role, because they can cause oxidative damage and tissue dysfunction and serve as molecular signals activating stress responses that are beneficial to the organism. Mitochondria have been thought to both play a major role in tissue oxidative damage and dysfunction and provide protection against excessive tissue dysfunction through several mechanisms, including stimulation of opening of permeability transition pores. Until recently, the functional significance of ROS sources different from mitochondria has received lesser attention. However, the most recent data, besides confirming the mitochondrial role in tissue oxidative stress and protection, show interplay between mitochondria and other ROS cellular sources, so that activation of one can lead to activation of other sources. Thus, it is currently accepted that in various conditions all cellular sources of ROS provide significant contribution to processes that oxidatively damage tissues and assure their survival, through mechanisms such as autophagy and apoptosis. PMID:27478531

[Evaluation of Cellular Effects Caused by Lunar Regolith Simulant Including Fine Particles].

PubMed

Horie, Masanori; Miki, Takeo; Honma, Yoshiyuki; Aoki, Shigeru; Morimoto, Yasuo

2015-06-01

The National Aeronautics and Space Administration has announced a plan to establish a manned colony on the surface of the moon, and our country, Japan, has declared its participation. The surface of the moon is covered with soil called lunar regolith, which includes fine particles. It is possible that humans will inhale lunar regolith if it is brought into the spaceship. Therefore, an evaluation of the pulmonary effects caused by lunar regolith is important for exploration of the moon. In the present study, we examine the cellular effects of lunar regolith simulant, whose components are similar to those of lunar regolith. We focused on the chemical component and particle size in particular. The regolith simulant was fractionated to < 10 μm, < 25 μm and 10-25 μm by gravitational sedimentation in suspensions. We also examined the cellular effects of fine regolith simulant whose primary particle size is 5.10 μm. These regolith simulants were applied to human lung carcinoma A549 cells at concentrations of 0.1 and 1.0 mg/ml. Cytotoxicity, oxidative stress and immune response were examined after 24 h exposure. Cell membrane damage, mitochondrial dysfunction and induction of Interleukin-8 (IL-8) were observed at the concentration of 1.0 mg/ml. The cellular effects of the regolith simulant at the concentration of 0.1 mg/ml were small, as compared with crystalline silica as a positive control. Secretion of IL-1β and tumor necrosis factor-α (TNF-α) was observed at the concentration of 1.0 mg/ml, but induction of gene expression was not observed at 24 h after exposure. Induction of cellular oxidative stress was small. Although the cellular effects tended to be stronger in the < 10 μm particles, there was no remarkable difference. These results suggest that the chemical components and particle size have little relationship to the cellular effects of lunar regolith simulant such as cell membrane damage, induction of oxidative stress and proinflammatory effect.

Changes in translation rate modulate stress-induced damage of diverse proteins

PubMed Central

Kim, Heejung

2013-01-01

Proteostasis is the maintenance of the proper function of cellular proteins. Hypertonic stress disrupts proteostasis and causes rapid and widespread protein aggregation and misfolding in the nematode Caenorhabditis elegans. Optimal survival in hypertonic environments requires degradation of damaged proteins. Inhibition of protein synthesis occurs in response to diverse environmental stressors and may function in part to minimize stress-induced protein damage. We recently tested this idea directly and demonstrated that translation inhibition by acute exposure to cycloheximide suppresses hypertonicity-induced aggregation of polyglutamine::YFP (Q35::YFP) in body wall muscle cells. In this article, we further characterized the relationship between protein synthesis and hypertonic stress-induced protein damage. We demonstrate that inhibition of translation reduces hypertonic stress-induced formation and growth of Q35::YFP, Q44::YFP, and α-synuclein aggregates; misfolding of paramyosin and ras GTPase; and aggregation of multiple endogenous proteins expressed in diverse cell types. Activation of general control nonderepressible-2 (GCN-2) kinase signaling during hypertonic stress inhibits protein synthesis via phosphorylation of eukaryotic initiation factor-2α (eIF-2α). Inhibition of GCN-2 activation prevents the reduction in translation rate and greatly exacerbates the formation and growth of Q35::YFP aggregates and the aggregation of endogenous proteins. The current studies together with our previous work provide the first direct demonstration that hypertonic stress-induced reduction in protein synthesis minimizes protein aggregation and misfolding. Reduction in translation rate also serves as a signal that activates osmoprotective gene expression. The cellular proteostasis network thus plays a critical role in minimizing hypertonic stress-induced protein damage, in degrading stress-damaged proteins, and in cellular osmosensing and signaling. PMID:24153430

A Continuum Damage Mechanics Model for the Static and Cyclic Fatigue of Cellular Composites

PubMed Central

Huber, Otto

2017-01-01

The fatigue behavior of a cellular composite with an epoxy matrix and glass foam granules is analyzed and modeled by means of continuum damage mechanics. The investigated cellular composite is a particular type of composite foam, and is very similar to syntactic foams. In contrast to conventional syntactic foams constituted by hollow spherical particles (balloons), cellular glass, mineral, or metal place holders are combined with the matrix material (metal or polymer) in the case of cellular composites. A microstructural investigation of the damage behavior is performed using scanning electron microscopy. For the modeling of the fatigue behavior, the damage is separated into pure static and pure cyclic damage and described in terms of the stiffness loss of the material using damage models for cyclic and creep damage. Both models incorporate nonlinear accumulation and interaction of damage. A cycle jumping procedure is developed, which allows for a fast and accurate calculation of the damage evolution for constant load frequencies. The damage model is applied to examine the mean stress effect for cyclic fatigue and to investigate the frequency effect and the influence of the signal form in the case of static and cyclic damage interaction. The calculated lifetimes are in very good agreement with experimental results. PMID:28809806

Feline Toxoplasmosis: Tumor Necrosis Factor, Nitric Oxide, and Free Radicals in Seropositive Cats.

PubMed

Faria, Joice L M; Couto, Caroline do; Wierzynski, Sheron L; Bottari, Nathieli B; Baldissera, Matheus D; Pereira, Wanderson A B; Da Silva, Aleksandro S

2018-02-01

Toxoplasma gondii is a cosmopolitan protozoan that causes disease in several species, including humans. In cats, these infections are usually asymptomatic, but in other species they can lead to high levels of inflammatory and cell damage markers, causing cellular damage. Therefore, the aim of this study was to measure levels of tumor necrosis factor (TNF-α), reactive oxygen species (ROS), and nitric oxide (nitrite/nitrate-NO x ) in the serum of cats seropositive for T. gondii. Initially, we investigated the presence of antibodies against T. gondii in cats in the city of Concordia, Santa Catarina, Brazil, with the use of indirect immunofluorescence (IFA), and found 30 cats seropositive for T. gondii and 30 seronegative cats. In this study, seropositive cats showed higher levels of TNF-α, ROS, and NO x compared to seronegative cats. Although cats do not show clinical signs of disease, constant inflammatory response can cause cell damage, which over time may adversely affect the animal.

A Review: Some biological effects of high LET radiations

NASA Technical Reports Server (NTRS)

Wiley, A., Jr.

1972-01-01

There are qualitative and quantitative differences in the biological damage observed after exposure to high LET radiation as compared to that caused by low LET radiations. This review is concerned with these differences, which are ultimately reflected at the biochemical, cellular and even whole animal levels. In general, high LET radiations seem to produce biochemical damage which is more severe and possibly less repairable. Experimental data for those effects are presented in terms of biochemical RBE's with consideration of both early and late manifestations. An LET independent process by which significant biochemical damage may result from protons, neutrons and negative pion mesons is discussed.

Repair of DNA Damage Induced by the Cytidine Analog Zebularine Requires ATR and ATM in Arabidopsis[OPEN

PubMed Central

Liu, Chun-Hsin; Finke, Andreas; Díaz, Mariana; Rozhon, Wilfried; Poppenberger, Brigitte; Baubec, Tuncay; Pecinka, Ales

2015-01-01

DNA damage repair is an essential cellular mechanism that maintains genome stability. Here, we show that the nonmethylable cytidine analog zebularine induces a DNA damage response in Arabidopsis thaliana, independent of changes in DNA methylation. In contrast to genotoxic agents that induce damage in a cell cycle stage-independent manner, zebularine induces damage specifically during strand synthesis in DNA replication. The signaling of this damage is mediated by additive activity of ATAXIA TELANGIECTASIA MUTATED AND RAD3-RELATED and ATAXIA TELANGIECTASIA MUTATED kinases, which cause postreplicative cell cycle arrest and increased endoreplication. The repair requires a functional STRUCTURAL MAINTENANCE OF CHROMOSOMES5 (SMC5)-SMC6 complex and is accomplished predominantly by synthesis-dependent strand-annealing homologous recombination. Here, we provide insight into the response mechanism for coping with the genotoxic effects of zebularine and identify several components of the zebularine-induced DNA damage repair pathway. PMID:26023162

Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Fengxia; Zhang, Minjie; University of Chinese Academy of Sciences, Beijing 100049

2014-10-03

Highlights: • ATM phosphorylates the opposite strand of the dimer in response to DNA damage. • The PETPVFRLT box of ATM plays a key role in its dimer dissociation in DNA repair. • The dephosphorylation of ATM is critical for dimer re-formation after DNA repair. - Abstract: The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage.more » Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair.« less

BAP1 and Cancer

PubMed Central

Carbone, Michele; Yang, Haining; Pass, Harvey I.; Krausz, Thomas; Testa, Joseph R.; Gaudino, Giovanni

2013-01-01

Preface BAP1 is a deubiquitylase that is found associated with multi-protein complexes that regulate key cellular pathways, including the cell cycle, cellular differentiation, cell death, gluconeogenesis and the DNA damage response (DDR). Recent findings indicate that germline BAP1 mutations cause a novel cancer syndrome, characterized, at least in the affected families studied so far, by the onset at an early age of benign melanocytic skin tumours with mutated BAP1, and later in life by a high incidence of mesothelioma, uveal melanoma, cutaneous melanoma and possibly additional cancers. PMID:23550303

Molecular responses of calreticulin genes to iron overload and bacterial challenge in channel catfish Ictalurus punctatus

USDA-ARS?s Scientific Manuscript database

Infection and inflammation are often accompanied by oxidative stress caused by the accumulation of reactive oxygen species which can be deleterious to the health of the host. Antioxidant defense mechanisms and components are crucial in limiting cellular and tissue-level damage and restoring homeosta...

Molecular responses of calreticulin genes to iron overload and bacterial challenge in channel catfish (Ictalurus punctatus)

USDA-ARS?s Scientific Manuscript database

Infection and inflammation are often accompanied by oxidative stress caused by the accumulation of reactive oxygen species which can be deleterious to the health of the host. Antioxidant defense mechanisms and components are crucial in limiting cellular and tissue-level damage and restoring homeosta...

Hyperglycemia and anthocyanin inhibit quercetin metabolism in HepG2 cells

USDA-ARS?s Scientific Manuscript database

A high glucose (Glu) milieu promotes generation of reactive oxygen species, which may not only cause cellular damage, but also modulate phase II enzymes that are responsible for the metabolism of flavonoids. Thus, we examined the effect of a high Glu milieu on quercetin (Q) metabolism in HepG2 cells...

Peripheral blood lymphocytes: a model for monitoring physiological adaptation to high altitude.

PubMed

Mariggiò, Maria A; Falone, Stefano; Morabito, Caterina; Guarnieri, Simone; Mirabilio, Alessandro; Pilla, Raffaele; Bucciarelli, Tonino; Verratti, Vittore; Amicarelli, Fernanda

2010-01-01

Depending on the absolute altitude and the duration of exposure, a high altitude environment induces various cellular effects that are strictly related to changes in oxidative balance. In this study, we used in vitro isolated peripheral blood lymphocytes as biosensors to test the effect of hypobaric hypoxia on seven climbers by measuring the functional activity of these cells. Our data revealed that a 21-day exposure to high altitude (5000 m) (1) increased intracellular Ca(2+) concentration, (2) caused a significant decrease in mitochondrial membrane potential, and (3) despite possible transient increases in intracellular levels of reactive oxygen species, did not significantly change the antioxidant and/or oxidative damage-related status in lymphocytes and serum, assessed by measuring Trolox-equivalent antioxidant capacity, glutathione peroxidase activity, vitamin levels, and oxidatively modified proteins and lipids. Overall, these results suggest that high altitude might cause an impairment in adaptive antioxidant responses. This, in turn, could increase the risk of oxidative-stress-induced cellular damage. In addition, this study corroborates the use of peripheral blood lymphocytes as an easily handled model for monitoring adaptive response to environmental challenge.

Genotoxic effect of ethacrynic acid and impact of antioxidants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, William M.; Hoffman, Jared D.; Loo, George, E-mail: g_loo@uncg.edu

It is known that ethacrynic acid (EA) decreases the intracellular levels of glutathione. Whether the anticipated oxidative stress affects the structural integrity of DNA is unknown. Therefore, DNA damage was assessed in EA-treated HCT116 cells, and the impact of several antioxidants was also determined. EA caused both concentration-dependent and time-dependent DNA damage that eventually resulted in cell death. Unexpectedly, the DNA damage caused by EA was intensified by either ascorbic acid or trolox. In contrast, EA-induced DNA damage was reduced by N-acetylcysteine and by the iron chelator, deferoxamine. In elucidating the DNA damage, it was determined that EA increased themore » production of reactive oxygen species, which was inhibited by N-acetylcysteine and deferoxamine but not by ascorbic acid and trolox. Also, EA decreased glutathione levels, which were inhibited by N-acetylcysteine. But, ascorbic acid, trolox, and deferoxamine neither inhibited nor enhanced the capacity of EA to decrease glutathione. Interestingly, the glutathione synthesis inhibitor, buthionine sulfoxime, lowered glutathione to a similar degree as EA, but no noticeable DNA damage was found. Nevertheless, buthionine sulfoxime potentiated the glutathione-lowering effect of EA and intensified the DNA damage caused by EA. Additionally, in examining redox-sensitive stress gene expression, it was found that EA increased HO-1, GADD153, and p21mRNA expression, in association with increased nuclear localization of Nrf-2 and p53 proteins. In contrast to ascorbic acid, trolox, and deferoxamine, N-acetylcysteine suppressed the EA-induced upregulation of GADD153, although not of HO-1. Overall, it is concluded that EA has genotoxic properties that can be amplified by certain antioxidants. - Highlights: • Ethacrynic acid (EA) caused cellular DNA damage. • EA-induced DNA damage was potentiated by ascorbic acid or trolox. • EA increased ROS production, not inhibited by ascorbic acid or trolox. • EA decreased glutathione levels, not prevented by ascorbic acid or trolox. • Buthionine sulfoxime intensified the DNA damage caused by EA.« less

Dandelion Extracts Protect Human Skin Fibroblasts from UVB Damage and Cellular Senescence

PubMed Central

Yang, Yafan; Li, Shuangshuang

2015-01-01

Ultraviolet (UV) irradiation causes damage in skin by generating excessive reactive oxygen species (ROS) and induction of matrix metalloproteinases (MMPs), leading to skin photoageing. Dandelion extracts have long been used for traditional Chinese medicine and native American medicine to treat cancers, hepatitis, and digestive diseases; however, less is known on the effects of dandelion extracts in skin photoageing. Here we found that dandelion leaf and flower extracts significantly protect UVB irradiation-inhibited cell viability when added before UVB irradiation or promptly after irradiation. Dandelion leaf and flower extracts inhibited UVB irradiation-stimulated MMP activity and ROS generation. Dandelion root extracts showed less action on protecting HDFs from UVB irradiation-induced MMP activity, ROS generation, and cell death. Furthermore, dandelion leaf and flower but not root extracts stimulated glutathione generation and glutathione reductase mRNA expression in the presence or absence of UVB irradiation. We also found that dandelion leaf and flower extracts help absorb UVB irradiation. In addition, dandelion extracts significantly protected HDFs from H2O2-induced cellular senescence. In conclusion, dandelion extracts especially leaf and flower extracts are potent protective agents against UVB damage and H2O2-induced cellular senescence in HDFs by suppressing ROS generation and MMP activities and helping UVB absorption. PMID:26576225

Pericyte function in the physiological central nervous system.

PubMed

Muramatsu, Rieko; Yamashita, Toshihide

2014-01-01

Damage to the central nervous system (CNS) leads to disruption of the vascular network, causing vascular dysfunction. Vascular dysfunction is the major event in the pathogenesis of CNS diseases and is closely associated with the severity of neuronal dysfunction. The suppression of vascular dysfunction has been considered a promising avenue to limit damage to the CNS, leading to efforts to clarify the cellular and molecular basis of vascular homeostasis maintenance. A reduction of trophic support and oxygen delivery due to circulatory insufficiency has long been regarded as a major cause of vascular damage. Moreover, recent studies provide a new perspective on the importance of the structural stability of blood vessels in CNS diseases. This updated article discusses emerging information on the key role of vascular integrity in CNS diseases, specially focusing on pericyte function. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Fruit as Potent Natural Antioxidants and Their Biological Effects.

PubMed

Gomes-Rochette, Neuza F; Da Silveira Vasconcelos, Mirele; Nabavi, Seyed M; Mota, Erika F; Nunes-Pinheiro, Diana C S; Daglia, Maria; De Melo, Dirce F

The consumption of fruit has increased in the last 20 years, along with the growing recognition of its nutritional and protective values. Many of the benefits of a diet rich in fruit are attributed to the presence of different bioactive substances, such as vitamins, carotenoids and phenolic compounds. Flavanoids, a class of phenolic compounds, present particular antioxidant activity and thus provide protection against cellular damage caused by reactive oxygen species. Research suggests that an increased intake of plant foods is associated with a reduced incidence of chronic disease. There is currently a great deal of interest in the study of antioxidants, in particular due to the discovery of the damaging effects of free radicals to the body. Thus, this review aims to address the beneficial effects of the antioxidants present in fruits, on the neutralization of reactive species and the reduction of any damage they may cause.

Spatiotemporal dynamics of DNA repair proteins following laser microbeam induced DNA damage – When is a DSB not a DSB?☆

PubMed Central

Reynolds, Pamela; Botchway, Stanley W.; Parker, Anthony W.; O’Neill, Peter

2013-01-01

The formation of DNA lesions poses a constant threat to cellular stability. Repair of endogenously and exogenously produced lesions has therefore been extensively studied, although the spatiotemporal dynamics of the repair processes has yet to be fully understood. One of the most recent advances to study the kinetics of DNA repair has been the development of laser microbeams to induce and visualize recruitment and loss of repair proteins to base damage in live mammalian cells. However, a number of studies have produced contradictory results that are likely caused by the different laser systems used reflecting in part the wavelength dependence of the damage induced. Additionally, the repair kinetics of laser microbeam induced DNA lesions have generally lacked consideration of the structural and chemical complexity of the DNA damage sites, which are known to greatly influence their reparability. In this review, we highlight the key considerations when embarking on laser microbeam experiments and interpreting the real time data from laser microbeam irradiations. We compare the repair kinetics from live cell imaging with biochemical and direct quantitative cellular measurements for DNA repair. PMID:23688615

Maintenance of cellular ATP level by caloric restriction correlates chronological survival of budding yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Joon-Seok; Lee, Cheol-Koo, E-mail: cklee2005@korea.ac.kr

Highlights: •CR decreases total ROS and mitochondrial superoxide during the chronological aging. •CR does not affect the levels of oxidative damage on protein and DNA. •CR contributes extension of chronological lifespan by maintenance of ATP level -- Abstract: The free radical theory of aging emphasizes cumulative oxidative damage in the genome and intracellular proteins due to reactive oxygen species (ROS), which is a major cause for aging. Caloric restriction (CR) has been known as a representative treatment that prevents aging; however, its mechanism of action remains elusive. Here, we show that CR extends the chronological lifespan (CLS) of budding yeastmore » by maintaining cellular energy levels. CR reduced the generation of total ROS and mitochondrial superoxide; however, CR did not reduce the oxidative damage in proteins and DNA. Subsequently, calorie-restricted yeast had higher mitochondrial membrane potential (MMP), and it sustained consistent ATP levels during the process of chronological aging. Our results suggest that CR extends the survival of the chronologically aged cells by improving the efficiency of energy metabolism for the maintenance of the ATP level rather than reducing the global oxidative damage of proteins and DNA.« less

Efficient DNA Repair: A Cell’s Fountain of Youth? | Center for Cancer Research

Cancer.gov

Given the central importance of the genome to a cell’s function, it is not surprising that there are a number of proteins devoted to sensing and repairing DNA damage. But what happens when these repair proteins do not work properly? Cancer is one possible outcome, and a growing body of evidence also indicates that the cellular response to DNA damage plays a key role in the aging process. This concept is supported by the fact that many premature aging syndromes are caused by mutations in DNA repair proteins.

Cellular damage suffered by equine embryos after exposure to cryoprotectants or cryopreservation by slow-freezing or vitrification.

PubMed

Hendriks, W K; Roelen, B A J; Colenbrander, B; Stout, T A E

2015-11-01

Equine embryos are cryopreserved by slow-freezing or vitrification. While small embryos (<300 μm) survive cryopreservation reasonably well, larger embryos do not. It is not clear if slow-freezing or vitrification is less damaging to horse embryos. To compare the type and extent of cellular damage suffered by small and large embryos during cryopreservation by slow-freezing vs. vitrification. Sixty-three Day 6.5-7 embryos were subdivided by size and assigned to one of 5 treatments: control, exposure to slow-freezing or vitrification cryoprotectants (CPs), and cryopreservation by either technique. After thawing/CP removal, embryos were stained with fluorescent stains for various parameters of cellular integrity, and assessed by multiphoton microscopy. Exposing large embryos to vitrification CPs resulted in more dead cells (6.8 ± 1.3%: 95% confidence interval [CI], 3.1-10.4%) than exposure to slow-freezing media (0.3 ± 0.1%; 95% CI 0.0-0.6%: P = 0.001). Cryopreservation by either technique induced cell death and cytoskeleton disruption. Vitrification of small embryos resulted in a higher proportion of cells with fragmented or condensed (apoptotic) nuclei (P = 0.002) than slow-freezing (6.7 ± 1.5%, 95% CI 3.0-10.4% vs. 5.0 ± 2.1%, 95% CI 4.0-14.0%). Slow-freezing resulted in a higher incidence of disintegrated embryos (P = 0.01) than vitrification. Mitochondrial activity was low in control embryos, and was not differentially affected by cryopreservation technique, whereas vitrification changed mitochondrial distribution from a homogenous crystalline pattern in control embryos to a heterogeneous granulated distribution in vitrified embryos (P = 0.05). Cryopreservation caused more cellular damage to large embryos than smaller ones. While vitrification is more practical, it is not advisable for large embryos due to a higher incidence of dead cells. The choice is less obvious for small embryos, as vitrification led to occasionally very high percentages of dead or damaged cells, but a lower incidence of embryo disintegration. Modifications that reduce the level of cellular damage induced by vitrification are required before it can be considered the method of choice for cryopreserving equine embryos. © 2014 EVJ Ltd.

[Role of green tea in oxidative stress prevention].

PubMed

Metro, D; Muraca, U; Manasseri, L

2006-01-01

Oxidative stress is a condition caused by an increase of Reactive Oxygen Species (ROS) or by a shortage of the mechanisms of cellular protection and antioxidant defence. ROS have a potential oxidative effect towards various cellular macromolecules: proteins, nucleic acids, proteoglycans, lipids, with consequent damages in several cellular districts and promotion of the ageing process of the organism. However, some substances are able to prevent and/or reduce the damages caused by ROS; therefore, they are defined antioxidant. The present research studied, in a group of subjects, the antioxidant effects of the green tea, that was administered with fruit and vegetables in a strictly controlled diet. 50 subjects were selected and requested to daily consume 2-3 fruit portions (especially pineapple), 3-5 portions of vegetables (especially tomato) and 2-3 glasses of green tea for about 2 months to integrate the controlled basic diet. Some indicators of the oxidative stress were measured in the plasma before and after the integration period. The integration of a basic diet with supplements of fruit, vegetables and green tea turned out to be able in increasing both plasmatic total antioxidant capacity and endogenous antioxidant levels and to reduce the lipid peroxidation of the membranes, suggesting a reduction of the oxidative stress. These data suggest that an adequate supplement of antioxidants can prevent oxidative stress and correlated pathologies.

Spectroscopic photoacoustics for assessing ischemic kidney damage

NASA Astrophysics Data System (ADS)

Berndl, Elizabeth S. L.; He, Xiaolin; Yuen, Darren A.; Kolios, Michael C.

2018-02-01

Ischemic reperfusion injuries (IRIs) are caused by return of blood to a tissue or organ after a period without oxygen or nutrients. Damage in the microvasculature causes an inflammatory response and heterogeneous scarring, which is associated with an increase in collagen in the extracellular matrix. Although most often associated with heart attacks and strokes, IRI also occurs when blood reperfuses a transplanted organ. Currently, monitoring for IRI is limited to biopsies, which are invasive and sample a limited area. In this work, we explored photoacoustic (PA) biomarkers of scarring. IRI events were induced in mice (n=2) by clamping the left renal artery, then re-establishing flow. At 53 days post-surgery, kidneys were saline perfused and cut in half laterally. One half was immediately imaged with a VevoX system (Fujifilm-VisualSonics, Toronto) in two near infrared ranges - 680 to 970 nm (NIR), and 1200 to 1350 nm (NIR II). The other half was decellularized and then imaged at NIR and NIR II. Regions of interest were manually identified and analyzed for each kidney. For both cellularized and decellularized samples, the PA signal ratio based on irradiation wavelengths of 715:930 nm was higher in damaged kidneys than for undamaged kidneys (p < 0.0001 for both). Damaged kidneys had ROIs with spectra indicating the presence of collagen in the NIR II range, while healthy kidneys did not. Collagen rich spectra were more apparent in decellularized kidneys, suggesting that in the cellularized samples, other components may be contributing to the signal. PA imaging using spectral ratios associated with collagen signatures may provide a non-invasive tool to determine areas of tissue damage due to IRIs.

Carbon monoxide-induced suspended animation protects against hypoxic damage in Caenorhabditis elegans

PubMed Central

Nystul, Todd G.; Roth, Mark B.

2004-01-01

Oxygen deprivation is a major cause of cellular damage and death. Here we demonstrate that Caenorhabditis elegans embryos, which can survive both in anoxia (<0.001 kPa O2) by entering into suspended animation and in mild hypoxia (0.25-1 kPa O2) through a hypoxia-inducible factor 1-mediated response, cannot survive in intermediate concentrations of oxygen, between 0.01 and 0.1 kPa O2. Moreover, we show that carbon monoxide can protect C. elegans embryos against hypoxic damage in this sensitive range. Carbon monoxide can also rescue the hypoxia-sensitive mutant hif-1(ia04) from lethality in hypoxia. This work defines the oxygen tensions over which hypoxic damage occurs in C. elegans embryos and demonstrates that carbon monoxide can prevent this damage by inducing suspended animation. PMID:15184665

Heart Repair and Regeneration: Recent Insights from Zebrafish Studies

PubMed Central

Lien, Ching-Ling; Harrison, Michael R.; Tuan, Tai-Lan; Starnes, Vaughn A

2012-01-01

Cardiovascular disease is the leading cause of death in United States and worldwide. Failure to properly repair or regenerate damaged cardiac tissues after myocardial infarction is a major cause of heart failure. In contrast to humans and other mammals, zebrafish hearts regenerate after substantial injury or tissue damage. Here, we review recent progress in studying zebrafish heart regeneration, addressing the molecular and cellular responses in the three tissue layers of the heart: myocardium, epicardium, and endocardium. We also compare different injury models utilized to study zebrafish heart regeneration, and discuss the differences in responses to injury between mammalian and zebrafish hearts. By learning how zebrafish hearts regenerate naturally, we can better design therapeutic strategies for repairing human hearts after myocardial infarction. PMID:22818295

Comprehensive Profiling of Radiosensitive Human Cell Lines with DNA Damage Response Assays Identifies the Neutral Comet Assay as a Potential Surrogate for Clonogenic Survival

PubMed Central

Nahas, Shareef A.; Davies, Robert; Fike, Francesca; Nakamura, Kotoka; Du, Liutao; Kayali, Refik; Martin, Nathan T.; Concannon, Patrick; Gatti, Richard A.

2015-01-01

In an effort to explore the possible causes of human radiosensitivity and identify more rapid assays for cellular radiosensitivity, we interrogated a set of assays that evaluate cellular functions involved in recognition and repair of DNA double-strand breaks: (1) neutral comet assay, (2) radiation-induced γ-H2AX focus formation, (3) the temporal kinetics of structural maintenance of chromosomes 1 phosphorylation, (4) intra-S-phase checkpoint integrity, and (5) mitochondrial respiration. We characterized a unique panel of 19 “radiosensitive” human lymphoblastoid cell lines from individuals with undiagnosed diseases suggestive of a DNA repair disorder. Radiosensitivity was defined by reduced cellular survival using a clonogenic survival assay. Each assay identified cell lines with defects in DNA damage response functions. The highest concordance rate observed, 89% (17/19), was between an abnormal neutral comet assay and reduced survival by the colony survival assay. Our data also suggested that the neutral comet assay would be a more rapid surrogate for analyzing DNA repair/processing disorders. PMID:21962002

The Translesion Polymerase Pol η Is Required for Efficient Epstein-Barr Virus Infectivity and Is Regulated by the Viral Deubiquitinating Enzyme BPLF1

PubMed Central

Dyson, Ossie F.; Pagano, Joseph S.

2017-01-01

ABSTRACT Epstein-Barr virus (EBV) infection and lytic replication are known to induce a cellular DNA damage response. We previously showed that the virally encoded BPLF1 protein interacts with and regulates several members of the translesion synthesis (TLS) pathway, a DNA damage tolerance pathway, and that these cellular factors enhance viral infectivity. BPLF1 is a late lytic cycle gene, but the protein is also packaged in the viral tegument, indicating that BPLF1 may function both early and late during infection. The BPLF1 protein expresses deubiquitinating activity that is strictly conserved across the Herpesviridae; mutation of the active site cysteine results in a loss of enzymatic activity. Infection with an EBV BPLF1 knockout virus results in decreased EBV infectivity. Polymerase eta (Pol η), a specialized DNA repair polymerase, functions in TLS and allows for DNA replication complexes to bypass lesions in DNA. Here we report that BPLF1 interacts with Pol η and that Pol η protein levels are increased in the presence of functional BPLF1. BPLF1 promotes a nuclear relocalization of Pol η molecules which are focus-like in appearance, consistent with the localization observed when Pol η is recruited to sites of DNA damage. Knockdown of Pol η resulted in decreased production of infectious virus, and further, Pol η was found to bind to EBV DNA, suggesting that it may allow for bypass of damaged viral DNA during its replication. The results suggest a mechanism by which EBV recruits cellular repair factors, such as Pol η, to sites of viral DNA damage via BPLF1, thereby allowing for efficient viral DNA replication. IMPORTANCE Epstein-Barr virus is the causative agent of infectious mononucleosis and infects approximately 90% of the world's population. It causes lymphomas in individuals with acquired and innate immune disorders and is strongly associated with Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B-cell lymphomas, nasopharyngeal carcinoma (NPC), and lymphomas that develop in organ transplant recipients. Cellular DNA damage is a major determinant in the establishment of oncogenic processes and is well studied, but there are few studies of endogenous repair of viral DNA. This work evaluates how EBV's BPLF1 protein and its conserved deubiquitinating activity regulate the cellular DNA repair enzyme polymerase eta and recruit it to potential sites of viral damage and replication, resulting in enhanced production of infectious virus. These findings help to establish how EBV enlists and manipulates cellular DNA repair factors during the viral lytic cycle, contributing to efficient infectious virion production. PMID:28724765

The Translesion Polymerase Pol η Is Required for Efficient Epstein-Barr Virus Infectivity and Is Regulated by the Viral Deubiquitinating Enzyme BPLF1.

PubMed

Dyson, Ossie F; Pagano, Joseph S; Whitehurst, Christopher B

2017-10-01

Epstein-Barr virus (EBV) infection and lytic replication are known to induce a cellular DNA damage response. We previously showed that the virally encoded BPLF1 protein interacts with and regulates several members of the translesion synthesis (TLS) pathway, a DNA damage tolerance pathway, and that these cellular factors enhance viral infectivity. BPLF1 is a late lytic cycle gene, but the protein is also packaged in the viral tegument, indicating that BPLF1 may function both early and late during infection. The BPLF1 protein expresses deubiquitinating activity that is strictly conserved across the Herpesviridae ; mutation of the active site cysteine results in a loss of enzymatic activity. Infection with an EBV BPLF1 knockout virus results in decreased EBV infectivity. Polymerase eta (Pol η), a specialized DNA repair polymerase, functions in TLS and allows for DNA replication complexes to bypass lesions in DNA. Here we report that BPLF1 interacts with Pol η and that Pol η protein levels are increased in the presence of functional BPLF1. BPLF1 promotes a nuclear relocalization of Pol η molecules which are focus-like in appearance, consistent with the localization observed when Pol η is recruited to sites of DNA damage. Knockdown of Pol η resulted in decreased production of infectious virus, and further, Pol η was found to bind to EBV DNA, suggesting that it may allow for bypass of damaged viral DNA during its replication. The results suggest a mechanism by which EBV recruits cellular repair factors, such as Pol η, to sites of viral DNA damage via BPLF1, thereby allowing for efficient viral DNA replication. IMPORTANCE Epstein-Barr virus is the causative agent of infectious mononucleosis and infects approximately 90% of the world's population. It causes lymphomas in individuals with acquired and innate immune disorders and is strongly associated with Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B-cell lymphomas, nasopharyngeal carcinoma (NPC), and lymphomas that develop in organ transplant recipients. Cellular DNA damage is a major determinant in the establishment of oncogenic processes and is well studied, but there are few studies of endogenous repair of viral DNA. This work evaluates how EBV's BPLF1 protein and its conserved deubiquitinating activity regulate the cellular DNA repair enzyme polymerase eta and recruit it to potential sites of viral damage and replication, resulting in enhanced production of infectious virus. These findings help to establish how EBV enlists and manipulates cellular DNA repair factors during the viral lytic cycle, contributing to efficient infectious virion production. Copyright © 2017 American Society for Microbiology.

Temperature-dependent rate models of vascular cambium cell mortality

Treesearch

Matthew B. Dickinson; Edward A. Johnson

2004-01-01

We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of...

Damage pattern as a function of radiation quality and other factors.

PubMed

Burkart, W; Jung, T; Frasch, G

1999-01-01

An understanding of damage pattern in critical cellular structures such as DNA is an important prerequisite for a mechanistic assessment of primary radiation damage, its possible repair, and the propagation of residual changes in somatic and germ cells as potential contributors to disease or ageing. Important quantitative insights have been made recently on the distribution in time and space of critical lesions from direct and indirect action of ionizing radiation on mammalian cells. When compared to damage from chemicals or from spontaneous degradation, e.g. depurination or base deamination in DNA, the potential of even low-LET radiation to create local hot spots of damage from single particle tracks is of utmost importance. This has important repercussions on inferences from critical biological effects at high dose and dose rate exposure situations to health risks at chronic, low-level exposures as experienced in environmental and controlled occupational settings. About 10,000 DNA lesions per human cell nucleus and day from spontaneous degradation and chemical attack cause no apparent effect, but a dose of 4 Gy translating into a similar number of direct and indirect DNA breaks induces acute lethality. Therefore, single lesions cannot explain the high efficiency of ionizing radiation in the induction of mutation, transformation and loss of proliferative capacity. Clustered damage leading to poorly repairable double-strand breaks or even more complex local DNA degradation, correlates better with fixed damage and critical biological endpoints. A comparison with other physical, chemical and biological agents indicates that ionizing radiation is indeed set apart from these by its unique micro- and nano-dosimetric traits. Only a few other agents such as bleomycin have a similar potential to cause complex damage from single events. However, in view of the multi-stage mechanism of carcinogenesis, it is still an open question whether dose-effect linearity for complex primary DNA damage and resulting fixed critical cellular lesions translate into linearity for radiation-induced cancer. To solve this enigma, a quantitative assessment of all genotoxic and harmful non-genotoxic agents affecting the human body would be needed.

Damage of photoreceptor-derived cells in culture induced by light emitting diode-derived blue light

PubMed Central

Kuse, Yoshiki; Ogawa, Kenjiro; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

2014-01-01

Our eyes are increasingly exposed to light from the emitting diode (LED) light of video display terminals (VDT) which contain much blue light. VDTs are equipped with televisions, personal computers, and smart phones. The present study aims to clarify the mechanism underlying blue LED light-induced photoreceptor cell damage. Murine cone photoreceptor-derived cells (661 W) were exposed to blue, white, or green LED light (0.38 mW/cm2). In the present study, blue LED light increased reactive oxygen species (ROS) production, altered the protein expression level, induced the aggregation of short-wavelength opsins (S-opsin), resulting in severe cell damage. While, blue LED light damaged the primary retinal cells and the damage was photoreceptor specific. N-Acetylcysteine (NAC), an antioxidant, protected against the cellular damage induced by blue LED light. Overall, the LED light induced cell damage was wavelength-, but not energy-dependent and may cause more severe retinal photoreceptor cell damage than the other LED light. PMID:24909301

Repair of Oxidative DNA Damage in Saccharomyces cerevisiae.

PubMed

Chalissery, Jisha; Jalal, Deena; Al-Natour, Zeina; Hassan, Ahmed H

2017-03-01

Malfunction of enzymes that detoxify reactive oxygen species leads to oxidative attack on biomolecules including DNA and consequently activates various DNA repair pathways. The nature of DNA damage and the cell cycle stage at which DNA damage occurs determine the appropriate repair pathway to rectify the damage. Oxidized DNA bases are primarily repaired by base excision repair and nucleotide incision repair. Nucleotide excision repair acts on lesions that distort DNA helix, mismatch repair on mispaired bases, and homologous recombination and non-homologous end joining on double stranded breaks. Post-replication repair that overcomes replication blocks caused by DNA damage also plays a crucial role in protecting the cell from the deleterious effects of oxidative DNA damage. Mitochondrial DNA is also prone to oxidative damage and is efficiently repaired by the cellular DNA repair machinery. In this review, we discuss the DNA repair pathways in relation to the nature of oxidative DNA damage in Saccharomyces cerevisiae. Copyright © 2017 Elsevier B.V. All rights reserved.

Antimicrobial role of human meibomian lipids at the ocular surface.

PubMed

Mudgil, Poonam

2014-10-14

Human meibomian lipids form the outermost lipid layer of the tear film and serve many important functions to maintain its integrity. Although not investigated earlier, these lipids may have antimicrobial properties that help in strengthening the innate host defense of tears at the ocular surface. The aim of this study was to investigate the antimicrobial role of human meibomian lipids. Ocular pathogenic bacteria, Staphylococcus aureus 31, Pseudomonas aeruginosa 19, Pseudomonas aeruginosa 20, and Serratia marcescens 35, were grown in the presence and absence of human meibomian lipids in an artificial tear solution at the physiological temperature. Viable counts were obtained to note the number of bacteria surviving the treatment with meibomian lipids. Bacterial cells were imaged using scanning electron microscopy to observe the damages caused by meibomian lipids. Viable count results showed that in the presence of meibomian lipids, growth of all bacteria was considerably lower. Scanning electron microscopy showed that meibomian lipids caused extensive cellular damage to bacteria as manifested in smaller size, loss of aggregation, abnormal phenotype, cellular distortion, damaged cell wall, and cell lysis. This is the first-ever report of the antimicrobial role of human meibomian lipids. These lipids possess antimicrobial properties against both Gram-positive and Gram-negative bacteria and are involved in the innate host defense of tears in protecting the ocular surface against microbial pathogens. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Basal autophagy maintains pancreatic acinar cell homeostasis and protein synthesis and prevents ER stress

PubMed Central

Antonucci, Laura; Fagman, Johan B.; Kim, Ju Youn; Todoric, Jelena; Gukovsky, Ilya; Mackey, Mason; Ellisman, Mark H.; Karin, Michael

2015-01-01

Pancreatic acinar cells possess very high protein synthetic rates as they need to produce and secrete large amounts of digestive enzymes. Acinar cell damage and dysfunction cause malnutrition and pancreatitis, and inflammation of the exocrine pancreas that promotes development of pancreatic ductal adenocarcinoma (PDAC), a deadly pancreatic neoplasm. The cellular and molecular mechanisms that maintain acinar cell function and whose dysregulation can lead to tissue damage and chronic pancreatitis are poorly understood. It was suggested that autophagy, the principal cellular degradative pathway, is impaired in pancreatitis, but it is unknown whether impaired autophagy is a cause or a consequence of pancreatitis. To address this question, we generated Atg7Δpan mice that lack the essential autophagy-related protein 7 (ATG7) in pancreatic epithelial cells. Atg7Δpan mice exhibit severe acinar cell degeneration, leading to pancreatic inflammation and extensive fibrosis. Whereas ATG7 loss leads to the expected decrease in autophagic flux, it also results in endoplasmic reticulum (ER) stress, accumulation of dysfunctional mitochondria, oxidative stress, activation of AMPK, and a marked decrease in protein synthetic capacity that is accompanied by loss of rough ER. Atg7Δpan mice also exhibit spontaneous activation of regenerative mechanisms that initiate acinar-to-ductal metaplasia (ADM), a process that replaces damaged acinar cells with duct-like structures. PMID:26512112

Altering Genomic Integrity: Heavy Metal Exposure Promotes Transposable Element-Mediated Damage.

PubMed

Morales, Maria E; Servant, Geraldine; Ade, Catherine; Roy-Engel, Astrid M

2015-07-01

Maintenance of genomic integrity is critical for cellular homeostasis and survival. The active transposable elements (TEs) composed primarily of three mobile element lineages LINE-1, Alu, and SVA comprise approximately 30% of the mass of the human genome. For the past 2 decades, studies have shown that TEs significantly contribute to genetic instability and that TE-caused damages are associated with genetic diseases and cancer. Different environmental exposures, including several heavy metals, influence how TEs interact with its host genome increasing their negative impact. This mini-review provides some basic knowledge on TEs, their contribution to disease, and an overview of the current knowledge on how heavy metals influence TE-mediated damage.

Spirally-patterned pinhole arrays for long-term fluorescence cell imaging.

PubMed

Koo, Bon Ung; Kang, YooNa; Moon, SangJun; Lee, Won Gu

2015-11-07

Fluorescence cell imaging using a fluorescence microscope is an extensively used technique to examine the cell nucleus, internal structures, and other cellular molecules with fluorescence response time and intensity. However, it is difficult to perform high resolution cell imaging for a long period of time with this technique due to necrosis and apoptosis depending on the type and subcellular location of the damage caused by phototoxicity. A large number of studies have been performed to resolve this problem, but researchers have struggled to meet the challenge between cellular viability and image resolution. In this study, we employ a specially designed disc to reduce cell damage by controlling total fluorescence exposure time without deterioration of the image resolution. This approach has many advantages such as, the apparatus is simple, cost-effective, and easily integrated into the optical pathway through a conventional fluorescence microscope.

Postradiation atrophy of mature bone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ergun, H.; Howland, W.J.

1980-01-01

The primary event of radiation damage to bone is atrophy and true necrosis of bone is uncommon. The postradiation atrophic changes of bone are the result of combined cellular and vascular damage, the former being more important. The damage to the osteoblast resulting in decreased matrix production is apparently the primary histopathologic event. Radiation damaged bone is susceptible to superimposed complications of fracture, infection, necrosis, and sarcoma. The primary radiographic evidence of atrophy, localized osteopenia, is late in appearing. Contrary to former views, the mature bone is quite radiosensitive and reacts quickly to even small doses of radiation. The differentiationmore » of postirradiation atrophy and metastasis may be difficult. Biopsy should be the last resort because of the possibility of causing true necrosis in atrophic bone by trauma and infection.« less

Human Parvovirus B19 Utilizes Cellular DNA Replication Machinery for Viral DNA Replication.

PubMed

Zou, Wei; Wang, Zekun; Xiong, Min; Chen, Aaron Yun; Xu, Peng; Ganaie, Safder S; Badawi, Yomna; Kleiboeker, Steve; Nishimune, Hiroshi; Ye, Shui Qing; Qiu, Jianming

2018-03-01

Human parvovirus B19 (B19V) infection of human erythroid progenitor cells (EPCs) induces a DNA damage response and cell cycle arrest at late S phase, which facilitates viral DNA replication. However, it is not clear exactly which cellular factors are employed by this single-stranded DNA virus. Here, we used microarrays to systematically analyze the dynamic transcriptome of EPCs infected with B19V. We found that DNA metabolism, DNA replication, DNA repair, DNA damage response, cell cycle, and cell cycle arrest pathways were significantly regulated after B19V infection. Confocal microscopy analyses revealed that most cellular DNA replication proteins were recruited to the centers of viral DNA replication, but not the DNA repair DNA polymerases. Our results suggest that DNA replication polymerase δ and polymerase α are responsible for B19V DNA replication by knocking down its expression in EPCs. We further showed that although RPA32 is essential for B19V DNA replication and the phosphorylated forms of RPA32 colocalized with the replicating viral genomes, RPA32 phosphorylation was not necessary for B19V DNA replication. Thus, this report provides evidence that B19V uses the cellular DNA replication machinery for viral DNA replication. IMPORTANCE Human parvovirus B19 (B19V) infection can cause transient aplastic crisis, persistent viremia, and pure red cell aplasia. In fetuses, B19V infection can result in nonimmune hydrops fetalis and fetal death. These clinical manifestations of B19V infection are a direct outcome of the death of human erythroid progenitors that host B19V replication. B19V infection induces a DNA damage response that is important for cell cycle arrest at late S phase. Here, we analyzed dynamic changes in cellular gene expression and found that DNA metabolic processes are tightly regulated during B19V infection. Although genes involved in cellular DNA replication were downregulated overall, the cellular DNA replication machinery was tightly associated with the replicating single-stranded DNA viral genome and played a critical role in viral DNA replication. In contrast, the DNA damage response-induced phosphorylated forms of RPA32 were dispensable for viral DNA replication. Copyright © 2018 American Society for Microbiology.

Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

PubMed

Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

2017-10-14

Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Unraveling the non-senescence phenomenon in Hydra.

PubMed

Dańko, Maciej J; Kozłowski, Jan; Schaible, Ralf

2015-10-07

Unlike other metazoans, Hydra does not experience the distinctive rise in mortality with age known as senescence, which results from an increasing imbalance between cell damage and cell repair. We propose that the Hydra controls damage accumulation mainly through damage-dependent cell selection and cell sloughing. We examine our hypothesis with a model that combines cellular damage with stem cell renewal, differentiation, and elimination. The Hydra individual can be seen as a large single pool of three types of stem cells with some features of differentiated cells. This large stem cell community prevents "cellular damage drift," which is inevitable in complex conglomerate (differentiated) metazoans with numerous and generally isolated pools of stem cells. The process of cellular damage drift is based on changes in the distribution of damage among cells due to random events, and is thus similar to Muller's ratchet in asexual populations. Events in the model that are sources of randomness include budding, cellular death, and cellular damage and repair. Our results suggest that non-senescence is possible only in simple Hydra-like organisms which have a high proportion and number of stem cells, continuous cell divisions, an effective cell selection mechanism, and stem cells with the ability to undertake some roles of differentiated cells. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Approaches for characterizing threshold dose-response relationships for DNA-damage pathways involved in carcinogenicity in vivo and micronuclei formation in vitro.

PubMed

Clewell, Rebecca A; Andersen, Melvin E

2016-05-01

Assessing the shape of dose-response curves for DNA-damage in cellular systems and for the consequences of DNA damage in intact animals remains a controversial topic. This overview looks at aspects of the pharmacokinetics (PK) and pharmacodynamics (PD) of cellular DNA-damage/repair and their role in defining the shape of dose-response curves using an in vivo example with formaldehyde and in vitro examples for micronuclei (MN) formation with several test compounds. Formaldehyde is both strongly mutagenic and an endogenous metabolite in cells. With increasing inhaled concentrations, there were transitions in gene changes, from activation of selective stress pathway genes at low concentrations, to activation of pathways for cell-cycle control, p53-DNA damage, and stem cell niche pathways at higher exposures. These gene expression changes were more consistent with dose-dependent transitions in the PD responses to formaldehyde in epithelial cells in the intact rat rather than the low-dose linear extrapolation methods currently used for carcinogens. However, more complete PD explanations of non-linear dose response for creation of fixed damage in cells require detailed examination of cellular responses in vitro using measures of DNA damage and repair that are not easily accessible in the intact animal. In the second section of the article, we illustrate an approach from our laboratory that develops fit-for-purpose, in vitro assays and evaluates the PD of DNA damage and repair through studies using prototypical DNA-damaging agents. Examination of a broad range of responses in these cells showed that transcriptional upregulation of cell cycle control and DNA repair pathways only occurred at doses higher than those causing overt damage fixed damage-measured as MN formation. Lower levels of damage appear to be handled by post-translational repair process using pre-existing proteins. In depth evaluation of the PD properties of one such post-translational process (formation of DNA repair centers; DRCs) has indicated that the formation of DRCs and their ability to complete repair before replication are consistent with threshold behaviours for mutagenesis and, by extension, with chemical carcinogenesis. © The Author 2016. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Fasting: Molecular Mechanisms and Clinical Applications

PubMed Central

Longo, Valter D.; Mattson, Mark P.

2014-01-01

Fasting has been practiced for millennia, but only recently studies have shed light on its role in adaptive cellular responses that reduce oxidative damage and inflammation, optimize energy metabolism and bolster cellular protection. In lower eukaryotes, chronic fasting extends longevity in part by reprogramming metabolic and stress resistance pathways. In rodents intermittent or periodic fasting protects against diabetes, cancers, heart disease and neurodegeneration, while in humans it helps reduce obesity, hypertension, asthma and rheumatoid arthritis. Thus, fasting has the potential to delay aging and help prevent and treat diseases while minimizing the side effects caused by chronic dietary interventions. PMID:24440038

Cellular defense against UVB-induced phototoxicity by cytosolic NADP(+)-dependent isocitrate dehydrogenase.

PubMed

Jo, Seung-Hee; Lee, So-Hyun; Chun, Hang Suk; Lee, Su Min; Koh, Ho-Jin; Lee, Sung-Eun; Chun, Jang-Soo; Park, Jeen-Woo; Huh, Tae-Lin

2002-03-29

Ultraviolet (UV) radiation is known as a major cause of skin photoaging and photocarcinogenesis. Many harmful effects of UV radiation are associated with the generation of reactive oxygen species. Recently, we have shown that NADP(+)-dependent isocitrate dehydrogenase is involved in the supply of NADPH needed for GSH production against cellular oxidative damage. In this study we investigated the role of cytosolic form of NADP(+)-dependent isocitrate dehydrogenase (IDPc) against UV radiation-induced cytotoxicity by comparing the relative degree of cellular responses in three different NIH3T3 cells with stable transfection with the cDNA for mouse IDPc in sense and antisense orientations, where IDPc activities were 2.3-fold higher and 39% lower, respectively, than that in the parental cells carrying the vector alone. Upon exposure to UVB (312 nm), the cells with low levels of IDPc became more sensitive to cell killing. Lipid peroxidation, protein oxidation, oxidative DNA damage, and intracellular peroxide generation were higher in the cell-line expressing the lower level of IDPc. However, the cells with the highly overexpressed IDPc exhibited enhanced resistance against UV radiation, compared to the control cells. The data indicate that IDPc plays an important role in cellular defense against UV radiation-induced oxidative injury. (c)2002 Elsevier Science (USA).

EMPOWERING ADULT STEM CELLS FOR MYOCARDIAL REGENERATION

PubMed Central

Mohsin, Sadia; Siddiqi, Sailay; Collins, Brett; Sussman, Mark A.

2012-01-01

Treatment strategies for heart failure remain a high priority for ongoing research due to the profound unmet need in clinical disease coupled with lack of significant translational progress. The underlying issue is the same whether the cause is acute damage, chronic stress from disease, or aging: progressive loss of functional cardiomyocytes and diminished hemodynamic output. To stave off cardiomyocyte losses, a number of strategic approaches have been embraced in recent years involving both molecular and cellular approaches to augment myocardial structure and performance. Resultant excitement surrounding regenerative medicine in the heart has been tempered by realizations that reparative processes in the heart are insufficient to restore damaged myocardium to normal functional capacity and that cellular cardiomyoplasty is hampered by poor survival, proliferation, engraftment and differentiation of the donated population. To overcome these limitations, a combination of molecular and cellular approaches needs to be adopted involving use of genetic engineering to enhance resistance to cell death and increase regenerative capacity. This review will highlight biological properties of approached to potentiate stem cell-mediated regeneration to promote enhanced myocardial regeneration, persistence of donated cells, and long lasting tissue repair. Optimizing cell delivery and harnessing the power of survival signaling cascades for ex vivo genetic modification of stem cells prior to reintroduction into the patient will be critical to enhance the efficacy of cellular cardiomyoplasty. Once this goal is achieved, then cell-based therapy has great promise for treatment of heart failure to combat the loss of cardiac structure and function associated with acute damage, chronic disease or aging. PMID:22158649

Mitochondrion-specific antioxidants as drug treatments for Alzheimer disease.

PubMed

Palacios, Hector H; Yendluri, Bharat B; Parvathaneni, Kalpana; Shadlinski, Vagif B; Obrenovich, Mark E; Leszek, Jerzy; Gokhman, Dmitry; Gąsiorowski, Kazimierz; Bragin, Valentin; Aliev, Gjumrakch

2011-03-01

Age-related dementias such as Alzheimer disease (AD) have been linked to vascular disorders like hypertension, diabetes and atherosclerosis. These risk factors cause ischemia, inflammation, oxidative damage and consequently reperfusion, which is largely due to reactive oxygen species (ROS) that are believed to induce mitochondrial damage. At higher concentrations, ROS can cause cell injury and death which occurs during the aging process, where oxidative stress is incremented due to an accelerated generation of ROS and a gradual decline in cellular antioxidant defense mechanisms. Neuronal mitochondria are especially vulnerable to oxidative stress due to their role in energy supply and use, causing a cascade of debilitating factors such as the production of giant and/or vulnerable young mitochondrion who's DNA has been compromised. Therefore, mitochondria specific antioxidants such as acetyl-L-carnitine and R-alphalipoic acid seem to be potential treatments for AD. They target the factors that damage mitochondria and reverse its effect, thus eliminating the imbalance seen in energy production and amyloid beta oxidation and making these antioxidants very powerful alternate strategies for the treatment of AD.

The Quinone Based Antitumor Agent Sepantronium Bromide (YM155) Causes Oxygen Independent Redox Activated Oxidative DNA Damage.

PubMed

Wani, Tasaduq Hussain; Surendran, Sreeraj; Jana, Anal; Chakrabarty, Anindita; Chowdhury, Goutam

2018-06-13

Sepantronium bromide (YM155) is a small molecule antitumor agent currently in phase II clinical trials. Although developed as survivin suppressor, YM155's primary mode of action has recently been found to be DNA damage. However, the mechanism of DNA damage by YM155 is still unknown. Knowing the mechanism of action of an anticancer drug is necessary to formulate a rational drug combination and select a cancer type for achieving maximum clinical efficacy. Using cell-based assays we showed that YM155 cause extensive DNA cleavage and reactive oxygen species generation. DNA cleavage by YM155 was found to be inhibited by radical scavengers and desferal. The reducing agent DTT and the cellular reducing system xanthine/xanthine oxidase were found to reductively activate YM155 and cause DNA cleavage. Unlike quinones, DNA cleavage by YM155 occurs in the presence of catalase and under hypoxic conditions indicating that hydrogen peroxide and oxygen is not necessary. Although YM155 is a quinone, it does not follow a typical quinone mechanism. Consistent with these observations a mechanism has been proposed that suggests that YM155 can cause oxidative DNA cleavage upon two electron reductive activation.

Cellular mechanisms against ischemia reperfusion injury induced by the use of anesthetic pharmacological agents.

PubMed

Álvarez, P; Tapia, L; Mardones, L A; Pedemonte, J C; Farías, J G; Castillo, R L

2014-07-25

Ischemia-reperfusion (IR) cycle in the myocardium is associated with activation of an injurious cascade, thus leading to new myocardial challenges, which account for up to 50% of infarct size. Some evidence implicates reactive oxygen species (ROS) as a probable cause of myocardial injury in prooxidant clinical settings. Damage occurs during both ischemia and post-ischemic reperfusion in animal and human models. The mechanisms that contribute to this damage include the increase in cellular calcium (Ca(2+)) concentration and induction of ROS sources during reperfusion. Pharmacological preconditioning, which includes pharmacological strategies that counteract the ROS burst and Ca(2+) overload followed to IR cycle in the myocardium, could be effective in limiting injury. Currently widespread evidence supports the use of anesthetics agents as an important cardioprotective strategy that act at various levels such as metabotropic receptors, ion channels or mitochondrial level. Their administration before a prolonged ischemic episode is known as anesthetic preconditioning, whereas when given at the very onset of reperfusion, is termed anesthetic postconditioning. Both types of anesthetic conditioning reduce, albeit not to the same degree, the extent of myocardial injury. This review focuses on cellular and pathophysiological concepts on the myocardial damage induced by IR and how anesthetic pharmacological agents commonly used could attenuate the functional and structural effects induced by oxidative stress in cardiac tissue. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Mechanisms of free radical-induced damage to DNA.

PubMed

Dizdaroglu, Miral; Jaruga, Pawel

2012-04-01

Endogenous and exogenous sources cause free radical-induced DNA damage in living organisms by a variety of mechanisms. The highly reactive hydroxyl radical reacts with the heterocyclic DNA bases and the sugar moiety near or at diffusion-controlled rates. Hydrated electron and H atom also add to the heterocyclic bases. These reactions lead to adduct radicals, further reactions of which yield numerous products. These include DNA base and sugar products, single- and double-strand breaks, 8,5'-cyclopurine-2'-deoxynucleosides, tandem lesions, clustered sites and DNA-protein cross-links. Reaction conditions and the presence or absence of oxygen profoundly affect the types and yields of the products. There is mounting evidence for an important role of free radical-induced DNA damage in the etiology of numerous diseases including cancer. Further understanding of mechanisms of free radical-induced DNA damage, and cellular repair and biological consequences of DNA damage products will be of outmost importance for disease prevention and treatment.

Apigenin attenuates streptozotocin-induced pancreatic β cell damage by its protective effects on cellular antioxidant defense.

PubMed

Wang, Ning; Yi, Wen Jing; Tan, Lu; Zhang, Jia Hui; Xu, Jiamin; Chen, Yi; Qin, Mengting; Yu, Shuang; Guan, Jing; Zhang, Rui

2017-06-01

Pancreatic beta cells are very sensitive to oxidative stress, which is one of the major causes of cell damages in diabetes. Growing interest has focused on the development of effective therapeutics to protect pancreatic cells from oxidative stress and searching for potentially protective antioxidants for treating diabetes. Apigenin, a plant-derived flavonoid, was investigated to determine whether it could protect rat insulinoma cell lines (RINm5F pancreatic beta cells) against streptozotocin (STZ)-induced oxidative damages and the mechanisms implicated. Our results showed that STZ treatment could induce oxidative stress and consequent cytotoxic effects in RINm5F cells. Pretreatment with apigenin effectively decreased the intracellular reactive oxygen species (ROS) production, attenuated cellular DNA damage, diminished lipid peroxidation, relieved protein carbonylation, and restored the cell apoptosis of pancreatic beta cells stressed by STZ. Our further experiments demonstrated that the beneficial effects of apigenin were related to ameliorate the loss of antioxidant enzymes of the STZ-treated cells in the level of gene transcription, protein expression, and enzyme activity. That suggested apigenin was not only a free radical scavenger but also a regulator to antioxidant defenses of pancreatic cells. Taken all together, our findings suggested that apigenin could attenuate the STZ-induced oxidative damages in pancreatic beta cells and might serve as a novel agent for the treatment of diabetes.

Oxidative Damage to RPA Limits the Nucleotide Excision Repair Capacity of Human Cells.

PubMed

Guven, Melisa; Brem, Reto; Macpherson, Peter; Peacock, Matthew; Karran, Peter

2015-11-01

Nucleotide excision repair (NER) protects against sunlight-induced skin cancer. Defective NER is associated with photosensitivity and a high skin cancer incidence. Some clinical treatments that cause photosensitivity can also increase skin cancer risk. Among these, the immunosuppressant azathioprine and the fluoroquinolone antibiotics ciprofloxacin and ofloxacin interact with UVA radiation to generate reactive oxygen species that diminish NER capacity by causing protein damage. The replication protein A (RPA) DNA-binding protein has a pivotal role in DNA metabolism and is an essential component of NER. The relationship between protein oxidation and NER inhibition was investigated in cultured human cells expressing different levels of RPA. We show here that RPA is limiting for NER and that oxidative damage to RPA compromises NER capability. Our findings reveal that cellular RPA is surprisingly vulnerable to oxidation, and we identify oxidized forms of RPA that are associated with impaired NER. The vulnerability of NER to inhibition by oxidation provides a connection between cutaneous photosensitivity, protein damage, and increased skin cancer risk. Our findings emphasize that damage to DNA repair proteins, as well as to DNA itself, is likely to be an important contributor to skin cancer risk.

Mitochondrial quality control: decommissioning power plants in neurodegenerative diseases.

PubMed

Mukherjee, Rukmini; Chakrabarti, Oishee

2013-01-01

The cell has an intricate quality control system to protect its mitochondria from oxidative stress. This surveillance system is multi-tiered and comprises molecules that are present inside the mitochondria, in the cytosol, and in other organelles like the nucleus and endoplasmic reticulum. These molecules cross talk with each other and protect the mitochondria from oxidative stress. Oxidative stress is a fundamental part of early disease pathogenesis of neurodegenerative diseases. These disorders also damage the cellular quality control machinery that protects the cell against oxidative stress. This exacerbates the oxidative damage and causes extensive neuronal cell death that is characteristic of neurodegeneration.

Milk thistle and olive extract: old substances with a new mission against sun-induced skin damage.

PubMed

DI Caprio, Roberta; Monfrecola, Giuseppe; Gasparri, Franco; Micillo, Raffaella; Balato, Anna; Lembo, Serena

2017-11-30

Natural antioxidants represent an effective option in the prevention and/or improvement of ultraviolet radiations (UVR)-induced/aggravated skin conditions. UVR cause DNA damage in keratinocytes, directly, in the form of cyclobutane pyrimidine dimers (CPDs), or indirectly, through oxidative stress production. Failure of the repair system can result in genetic mutations primarily responsible for the initiation of NMSCs. The aim of our study was to evaluate the in vitro protective effect of milk thistle and olive purified extracts on cultured keratinocytes after solar simulator irradiations (SSR). Immortalized keratinocytes were pre-incubated with different concentrations of milk thistle and olive purified extracts, and irradiated with increasing doses of SSR. Thereafter, CPDs and p53 expression were evaluated to assess DNA damage, whereas cellular antioxidants consumption and lipid membranes peroxidation were measured to analyse oxidative stress. The study substances were well tolerated by cells and displayed good cytoprotective and anti-oxidant activities, being milk thistle dry extract more effective in limiting the direct DNA damage, and olive extract particularly able to reduce lipid membrane peroxidation and to increase cellular antioxidants. Both study substances can be defined as safe compounds, showing differential cytoprotective and anti-oxidant activities and might represent interesting options for NMSCs chemoprevention.

E6AP is Required for Human Papillomavirus type 16 E6 to Cause Cervical Cancer in Mice

PubMed Central

Shai, Anny; Pitot, Henry C.; Lambert, Paul F.

2010-01-01

High-risk human papillomaviruses cause certain anogenital and head and neck cancers. E6, one of three potent HPV oncogenes that contribute to the development of these malignancies, is a multifunctional protein with many biochemical activities. Among these activities are its ability to bind and inactivate the cellular tumor suppressor p53, induce expression of telomerase, and bind to various other proteins including Bak, E6BP1, E6TP1, and proteins that contain PDZ domains such as hScrib and hDlg. Many of these activities are thought to contribute to E6’s role in carcinogenesis. E6’s interaction with many of these cellular proteins, including p53, leads to their destabilization. This property is mediated at least in part through E6’s ability to recruit the ubiquitin ligase, E6AP into complexes with these cellular proteins resulting in their ubiquitin–mediated degradation by the proteasome. In this study, we address the requirement for E6AP in mediating E6's acute and oncogenic phenotypes, including induction of epithelial hyperplasia, abrogation of DNA damage response and induction of cervical cancer. Loss of E6AP had no discernable effect on E6's ability to induce hyperplasia or abrogate DNA damage responses, akin to what we had earlier observed in the mouse epidermis. Nevertheless, in cervical carcinogenesis studies, there was a complete loss of E6’s oncogenic potential in mice nulligenic for E6AP. Thus, E6AP is absolutely required for E6 to cause cervical cancer. PMID:20530688

E6-associated protein is required for human papillomavirus type 16 E6 to cause cervical cancer in mice.

PubMed

Shai, Anny; Pitot, Henry C; Lambert, Paul F

2010-06-15

High-risk human papillomaviruses (HPV) cause certain anogenital and head and neck cancers. E6, one of three potent HPV oncogenes that contribute to the development of these malignancies, is a multifunctional protein with many biochemical activities. Among these activities are its ability to bind and inactivate the cellular tumor suppressor p53, induce expression of telomerase, and bind to various other proteins, including Bak, E6BP1, and E6TP1, and proteins that contain PDZ domains, such as hScrib and hDlg. Many of these activities are thought to contribute to the role of E6 in carcinogenesis. The interaction of E6 with many of these cellular proteins, including p53, leads to their destabilization. This property is mediated at least in part through the ability of E6 to recruit the ubiquitin ligase E6-associated protein (E6AP) into complexes with these cellular proteins, resulting in their ubiquitin-mediated degradation by the proteasome. In this study, we address the requirement for E6AP in mediating acute and oncogenic phenotypes of E6, including induction of epithelial hyperplasia, abrogation of DNA damage response, and induction of cervical cancer. Loss of E6AP had no discernible effect on the ability of E6 to induce hyperplasia or abrogate DNA damage responses, akin to what we had earlier observed in the mouse epidermis. Nevertheless, in cervical carcinogenesis studies, there was a complete loss of the oncogenic potential of E6 in mice nulligenic for E6AP. Thus, E6AP is absolutely required for E6 to cause cervical cancer.

Functional characterization of novel genotypes and cellular oxidative stress studies in propionic acidemia.

PubMed

Gallego-Villar, Lorena; Pérez-Cerdá, Celia; Pérez, Belén; Abia, David; Ugarte, Magdalena; Richard, Eva; Desviat, Lourdes R

2013-09-01

Propionic acidemia (PA), caused by a deficiency of the mitochondrial biotin dependent enzyme propionyl-CoA carboxylase (PCC) is one of the most frequent organic acidurias in humans. PA is caused by mutations in either the PCCA or PCCB genes encoding the α- and β-subunits of the PCC enzyme which are assembled as an α6β6 dodecamer. In this study we have investigated the molecular basis of the defect in ten fibroblast samples from PA patients. Using homology modeling with the recently solved crystal structure of the PCC holoenzyme and a eukaryotic expression system we have analyzed the structural and functional effect of novel point mutations, also revealing a novel splice defect by minigene analysis. In addition, we have investigated the contribution of oxidative stress to cellular damage measuring reactive oxygen species (ROS) levels and apoptosis parameters in patient fibroblasts, as recent studies point to a secondary mitochondrial dysfunction as pathophysiological mechanism in this disorder. The results show an increase in intracellular ROS content compared to controls, correlating with the activation of the JNK and p38 signaling pathways. Highest ROS levels were present in cells harboring functionally null mutations, including one severe missense mutation. This work provides molecular insight into the pathogenicity of PA variants and indicates that oxidative stress may be a major contributing factor to the cellular damage, supporting the proposal of antioxidant strategies as novel supplementary therapy in this rare disease.

The nucleus is the target for radiation-induced chromosomal instability

NASA Technical Reports Server (NTRS)

Kaplan, M. I.; Morgan, W. F.

1998-01-01

We have previously described chromosomal instability in cells of a human-hamster hybrid cell line after exposure to X rays. Chromosomal instability in these cells is characterized by the appearance of novel chromosomal rearrangements multiple generations after exposure to ionizing radiation. To identify the cellular target(s) for radiation-induced chromosomal instability, cells were treated with 125I-labeled compounds and frozen. Radioactive decays from 125I cause damage to the cell primarily at the site of their decay, and freezing the cells allows damage to accumulate in the absence of other cellular processes. We found that the decay of 125I-iododeoxyuridine, which is incorporated into the DNA, caused chromosomal instability. While cell killing and first-division chromosomal rearrangements increased with increasing numbers of 125I decays, the frequency of chromosomal instability was independent of dose. Chromosomal instability could also be induced from incorporation of 125I-iododeoxyuridine without freezing the cells for accumulation of decays. This indicates that DNA double-strand breaks in frozen cells resulting from 125I decays failed to lead to instability. Incorporation of an 125I-labeled protein (125I-succinyl-concanavalin A), which was internalized into the cell and/or bound to the plasma membrane, neither caused chromosomal instability nor potentiated chromosomal instability induced by 125I-iododeoxyuridine. These results show that the target for radiation-induced chromosomal instability in these cells is the nucleus.

Laboratory and clinical studies of cancer chemoprevention by antioxidants in berries.

PubMed

Stoner, Gary David; Wang, Li-Shu; Casto, Bruce Cordell

2008-09-01

Reactive oxygen species (ROS) are a major cause of cellular injury in an increasing number of diseases, including cancer. Most ROS are created in the cell through normal cellular metabolism. They can be produced by environmental insults such as ultraviolet light and toxic chemicals, as well as by the inflammatory process. Interception of ROS or limiting their cellular effects is a major role of antioxidants. Due to their content of phenolic and flavonoid compounds, berries exhibit high antioxidant potential, exceeding that of many other foodstuffs. Through their ability to scavenge ROS and reduce oxidative DNA damage, stimulate antioxidant enzymes, inhibit carcinogen-induced DNA adduct formation and enhance DNA repair, berry compounds have been shown to inhibit mutagenesis and cancer initiation. Berry constituents also influence cellular processes associated with cancer progression including signaling pathways associated with cell proliferation, differentiation, apoptosis and angiogenesis. This review article summarizes laboratory and human studies, demonstrating the protective effects of berries and berry constituents on oxidative and other cellular processes leading to cancer development.

Laboratory and clinical studies of cancer chemoprevention by antioxidants in berries

PubMed Central

Stoner, Gary David; Wang, Li-Shu; Casto, Bruce Cordell

2008-01-01

Reactive oxygen species (ROS) are a major cause of cellular injury in an increasing number of diseases, including cancer. Most ROS are created in the cell through normal cellular metabolism. They can be produced by environmental insults such as ultraviolet light and toxic chemicals, as well as by the inflammatory process. Interception of ROS or limiting their cellular effects is a major role of antioxidants. Due to their content of phenolic and flavonoid compounds, berries exhibit high antioxidant potential, exceeding that of many other foodstuffs. Through their ability to scavenge ROS and reduce oxidative DNA damage, stimulate antioxidant enzymes, inhibit carcinogen-induced DNA adduct formation and enhance DNA repair, berry compounds have been shown to inhibit mutagenesis and cancer initiation. Berry constituents also influence cellular processes associated with cancer progression including signaling pathways associated with cell proliferation, differentiation, apoptosis and angiogenesis. This review article summarizes laboratory and human studies, demonstrating the protective effects of berries and berry constituents on oxidative and other cellular processes leading to cancer development. PMID:18544560

Cellular cytotoxic response induced by highly purified multi-wall carbon nanotube in human lung cells.

PubMed

Tsukahara, Tamotsu; Haniu, Hisao

2011-06-01

Carbon nanotubes, a promising nanomaterial with unique characteristics, have applications in a variety of fields. The cytotoxic effects of carbon nanotubes are partially due to the induction of oxidative stress; however, the detailed mechanisms of nanotube cytotoxicity and their interaction with cells remain unclear. In this study, the authors focus on the acute toxicity of vapor-grown carbon fiber, HTT2800, which is one of the most highly purified multi-wall carbon nanotubes (MWCNT) by high-temperature thermal treatment. The authors exposed human bronchial epithelial cells (BEAS-2B) to HTT2800 and measured the cellular uptake, mitochondrial function, cellular LDH release, apoptotic signaling, reactive oxygen species (ROS) generation and pro-inflammatory cytokine release. The HTT2800-exposed cells showed cellular uptake of the carbon nanotube, increased cell death, enhanced DNA damage, and induced cytokine release. However, the exposed cells showed no obvious intracellular ROS generation. These cellular and molecular findings suggest that HTT2800 could cause a potentially adverse inflammatory response in BEAS-2B cells.

Fluid resuscitation: past, present, and the future.

PubMed

Santry, Heena P; Alam, Hasan B

2010-03-01

Hemorrhage remains a major cause of preventable death following both civilian and military trauma. The goals of resuscitation in the face of hemorrhagic shock are restoring end-organ perfusion and maintaining tissue oxygenation while attempting definitive control of bleeding. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. This article reviews the historical development and scientific underpinnings of modern resuscitation techniques. We summarized data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids, including isotonic crystalloids, natural and artificial colloids, hypertonic and hyperoncotic solutions, and artificial oxygen carriers, on cellular injury and how these relate to clinical practice. The data reveal that a uniformly safe, effective, and practical resuscitation fluid when blood products are unavailable and direct hemorrhage control is delayed has been elusive. Yet, it is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. Thus, we describe how some novel resuscitation strategies aimed at preventing or ameliorating cellular injury may become clinically available in the future.

Human T cell lymphotropic virus type I genomic expression and impact on intracellular signaling pathways during neurodegenerative disease and leukemia.

PubMed

Yao, J; Wigdahl, B

2000-01-01

HTLV-I has been identified as the etiologic agent of neoplasia within the human peripheral blood T lymphocyte population, and a progressive neurologic disorder based primarily within the central nervous system. We have examined the role of HTLV-I in these two distinctly different clinical syndromes by examining the life cycle of the virus, with emphasis on the regulation of viral gene expression within relevant target cell populations. In particular, we have examined the impact of specific viral gene products, particularly Tax, on cellular metabolic function. Tax is a highly promiscuous and pleiotropic viral oncoprotein, and is the most important factor contributing to the initial stages of viral-mediated transformation of T cells after HTLV-I infection. Tax, which weakly binds to Tax response element 1 (TRE-1) in the viral long terminal repeat (LTR), can dramatically trans-activate viral gene expression by interacting with cellular transcription factors, such as activated transcription factors and cyclic AMP response element binding proteins (ATF/CREB), CREB binding protein (CBP/p300), and factors involved with the basic transcription apparatus. At the same time, Tax alters cellular gene expression by directly or indirectly interacting with a variety of cellular transcription factors, cell cycle control elements, and cellular signal transduction molecules ultimately resulting in dysregulated cell proliferation. The mechanisms associated with HTLV-I infection, leading to tropical spastic paraparesis (TSP) are not as clearly resolved. Possible explanations of viral-induced neurologic disease range from central nervous system (CNS) damage caused by direct viral invasion of the CNS to bystander CNS damage caused by the immune response to HTLV-I infection. It is interesting to note that it is very rare for an HTLV-I infected individual to develop both adult T cell leukemia (ATL) and TSP in his/her life time, suggesting that the mechanisms governing development of these two diseases are mutually exclusive.

Ionization Cross Sections and Dissociation Channels of the DNA Sugar-Phosphate Backbone by Electron Collisions

NASA Technical Reports Server (NTRS)

Dateo, Christopher; Huo, Winifred M.; Fletcher, Graham D.

2004-01-01

It has been suggested that the genotoxic effects of ionizing radiation in living cells are not caused by the highly energetic incident radiation, but rather are induced by less energetic secondary species generated, the most abundant of which are free electrons.' The secondary electrons will further react to cause DNA damage via indirect and direct mechanisms. Detailed knowledge of these mechanisms is ultimately important for the development of global models of cellular radiation damage. We are studying one possible mechanism for the formation cf DNA strand breaks involving dissociative ionization of the DNA sugar-phosphate backbone induced by secondary electron co!lisions. We will present ionization cross sections at electron collision energies between threshold and 10 KeV using the improved binary encounter dipole (iBED) formulation' Preliminary results of the possible dissociative ionization pathways will be presented. It is speculated that radical fragments produced from the dissociative ionization can further react, providing a possible mechanism for double strand breaks and base damage.

Damage to cellular DNA from particulate radiations, the efficacy of its processing and the radiosensitivity of mammalian cells. Emphasis on DNA double strand breaks and chromatin breaks

NASA Technical Reports Server (NTRS)

Lett, J. T.

1992-01-01

For several years, it has been evident that cellular radiation biology is in a necessary period of consolidation and transition (Lett 1987, 1990; Lett et al. 1986, 1987). Both changes are moving apace, and have been stimulated by studies with heavy charged particles. From the standpoint of radiation chemistry, there is now a consensus of opinion that the DNA hydration shell must be distinguished from bulk water in the cell nucleus and treated as an integral part of DNA (chromatin) (Lett 1987). Concomitantly, sentiment is strengthening for the abandonment of the classical notions of "direct" and "indirect" action (Fielden and O'Neill 1991; O'Neill 1991; O'Neill et al. 1991; Schulte-Frohlinde and Bothe 1991 and references therein). A layer of water molecules outside, or in the outer edge of, the DNA (chromatin) hydration shell influences cellular radiosensitivity in ways not fully understood. Charge and energy transfer processes facilitated by, or involving, DNA hydration must be considered in rigorous theories of radiation action on cells. The induction and processing of double stand breaks (DSBs) in DNA (chromatin) seem to be the predominant determinants of the radiotoxicity of normally radioresistant mammalian cells, the survival curves of which reflect the patterns of damage induced and the damage present after processing ceases, and can be modelled in formal terms by the use of reaction (enzyme) kinetics. Incongruities such as sublethal damage are neither scientifically sound nor relevant to cellular radiation biology (Calkins 1991; Lett 1990; Lett et al. 1987a). Increases in linear energy transfer (LET infinity) up to 100-200 keV micron-1 cause increases in the extents of neighboring chemical and physical damage in DNA denoted by the general term DSB. Those changes are accompanied by decreasing abilities of cells normally radioresistant to sparsely ionizing radiations to process DSBs in DNA and chromatin and to recover from radiation exposure, so they make significant contributions to the relative biological effectiveness (RBE) of a given radiation.(ABSTRACT TRUNCATED AT 400 WORDS).

Apoptosis Modulation in the Immune System Reveals a Role of Neutrophils in Tissue Damage in a Murine Model of Chlamydial Genital Infection.

PubMed

Zortel, Tom; Schmitt-Graeff, Annette; Kirschnek, Susanne; Häcker, Georg

2018-05-05

Chlamydial infection frequently causes damage to the female genital tract. The precise mechanisms of chlamydial clearance and tissue damage are unknown, but studies suggest immunopathology with a particular role of neutrophils. The goal of this study was to understand the contribution of the immune system, in particular neutrophils. Using Chlamydia muridarum, we infected mice with a prolonged immune response due to expression of B-cell lymphoma 2 (Bcl-2) in hematopoietic cells (Bcl-2 mice), and mice where mature neutrophils are lacking due to the deletion of Myeloid cell leukemia 1 (Mcl-1) in myeloid cells (LysM-cre-mcl-1-flox mice; Mcl-1 mice). We monitored bacterial clearance, cellular infiltrate, and long-term tissue damage. Both mutant strains showed slightly delayed clearance of the acute infection. Bcl-2 mice had a strongly increased inflammatory infiltrate concerning almost all cell lineages. The infection of Bcl-2 mice caused increased tissue damage. The loss of neutrophils in Mcl-1 mice was associated with substantial quantitative and qualitative alterations of the inflammatory infiltrate. Mcl-1 mice had higher chlamydial burden and reduced tissue damage, including lower incidence of hydrosalpinx and less uterine dilation. Inhibition of apoptosis in the hematopoietic system increases inflammation and tissue damage. Neutrophils have broad functions, including a role in chlamydial clearance and in tissue destruction.

Attenuation of tumor necrosis factor-induced endothelial cell cytotoxicity and neutrophil chemiluminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, H.; Crowley, J.J.; Chan, J.C.

Our laboratory has previously shown that the administration of tumor necrosis factor (TNF), a cytokine produced by activated mononuclear cells, to guinea pigs produces a syndrome similar to gram-negative sepsis or ARDS. Pentoxifylline (PTX), a methylxanthine, protects against TNF-induced and sepsis-induced acute lung injury in vivo. We now report on in vitro cellular studies of PMN-mediated cellular injury and its attenuation. We studied TNF-induced bovine pulmonary artery endothelial cell (EC) cytotoxicity both with and without PMN. A 51Cr release assay was used to measure EC damage. Further, we investigated PMN function in response to TNF by measuring chemiluminescence. Agents thatmore » attenuate EC damage and PMN activation were evaluated in the above assays. Results revealed that TNF causes EC injury (p less than 0.05) and PMN increase TNF-induced EC injury. Furthermore, PTX, aminophylline (AMPH), caffeine, and forskolin attenuate TNF-induced EC cytotoxicity only in the presence of PMN (p less than 0.05). Of interest, dibutyryl cAMP (DBcAMP) protects EC from TNF-induced injury both with and without PMN. Agents that may increase cAMP levels in PMN (PTX, DBcAMP, forskolin, isobutyl methylxanthine, and terbutaline) significantly attenuate TNF-induced PMN chemiluminescence (p less than 0.05). We conclude that TNF causes EC damage and PMN increase this damage. Furthermore, PTX, AMPH, caffeine, and forskolin can attenuate TNF-induced EC injury in the presence of PMN, whereas DBcAMP attenuates TNF-induced EC injury with and without PMN. In addition, agents that may increase intracellular cAMP levels in PMN can attenuate TNF-induced PMN chemiluminescence. Thus, these agents likely attenuate TNF-induced PMN-mediated EC injury through their inhibitory effects on PMN.« less

Effect of Gold Nanorod Surface Chemistry on Cellular Response

DTIC Science & Technology

2011-03-15

distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Recently gold nanoparticles (Au NPs) have shown promising biological and military applications...tion after exposure to nanoparticles , but Trypan Blue exclusion assay and protein quantification did not show increased cell viability. It was...the literature showed that nanoparticles caused DNA damage to cells indirectly, without ever being directly exposed to or taken up by the cells.45 It is

Fasting: molecular mechanisms and clinical applications.

PubMed

Longo, Valter D; Mattson, Mark P

2014-02-04

Fasting has been practiced for millennia, but, only recently, studies have shed light on its role in adaptive cellular responses that reduce oxidative damage and inflammation, optimize energy metabolism, and bolster cellular protection. In lower eukaryotes, chronic fasting extends longevity, in part, by reprogramming metabolic and stress resistance pathways. In rodents intermittent or periodic fasting protects against diabetes, cancers, heart disease, and neurodegeneration, while in humans it helps reduce obesity, hypertension, asthma, and rheumatoid arthritis. Thus, fasting has the potential to delay aging and help prevent and treat diseases while minimizing the side effects caused by chronic dietary interventions. Copyright © 2014 Elsevier Inc. All rights reserved.

Magnetic nanoparticles: reactive oxygen species generation and potential therapeutic applications

NASA Astrophysics Data System (ADS)

Mai, Trang; Hilt, J. Zach

2017-07-01

Magnetic nanoparticles have been demonstrated to produce reactive oxygen species (ROS), which play a major role in various cellular pathways, via Fenton and Haber-Weiss reaction. ROS act as a double-edged sword inside the body. At normal conditions, the generation of ROS is in balance with their elimination by scavenger systems, and they can promote cell proliferation as well as differentiation. However, at an increased level, they can cause damages to protein, lead to cellular apoptosis, and contribute to many diseases including cancer. Many recent studies proposed a variety of strategies to either suppress toxicity of ROS generation or exploit the elevated ROS levels for cancer therapy.

Influenza A Virus Infection Damages Zebrafish Skeletal Muscle and Exacerbates Disease in Zebrafish Modeling Duchenne Muscular Dystrophy

PubMed Central

Goody, Michelle; Jurczyszak, Denise; Kim, Carol; Henry, Clarissa

2017-01-01

INTRODUCTION: Both genetic and infectious diseases can result in skeletal muscle degeneration, inflammation, pain, and/or weakness. Duchenne muscular dystrophy (DMD) is the most common congenital muscle disease. DMD causes progressive muscle wasting due to mutations in Dystrophin. Influenza A and B viruses are frequently associated with muscle complications, especially in children. Infections activate an immune response and immunosuppressant drugs reduce DMD symptoms. These data suggest that the immune system may contribute to muscle pathology. However, roles of the immune response in DMD and Influenza muscle complications are not well understood. Zebrafish with dmd mutations are a well-characterized model in which to study the molecular and cellular mechanisms of DMD pathology. We recently showed that zebrafish can be infected by human Influenza A virus (IAV). Thus, the zebrafish is a powerful system with which to ask questions about the etiology and mechanisms of muscle damage due to genetic and/or infectious diseases. METHODS: We infected zebrafish with IAV and assayed muscle tissue structure, sarcolemma integrity, cell-extracellular matrix (ECM) attachment, and molecular and cellular markers of inflammation in response to IAV infection alone or in the context of DMD. RESULTS: We find that IAV-infected zebrafish display mild muscle degeneration with sarcolemma damage and compromised ECM adhesion. An innate immune response is elicited in muscle in IAV-infected zebrafish: NFkB signaling is activated, pro-inflammatory cytokine expression is upregulated, and neutrophils localize to sites of muscle damage. IAV-infected dmd mutants display more severe muscle damage than would be expected from an additive effect of dmd mutation and IAV infection, suggesting that muscle damage caused by Dystrophin-deficiency and IAV infection is synergistic. DISCUSSION: These data demonstrate the importance of preventing IAV infections in individuals with genetic muscle diseases. Elucidating the mechanisms of immune-mediated muscle damage will not only apply to DMD and IAV, but also to other conditions where the immune system, inflammation, and muscle tissue are known to be affected, such as autoimmune diseases, cancer, and aging. PMID:29188128

Influenza A Virus Infection Damages Zebrafish Skeletal Muscle and Exacerbates Disease in Zebrafish Modeling Duchenne Muscular Dystrophy.

PubMed

Goody, Michelle; Jurczyszak, Denise; Kim, Carol; Henry, Clarissa

2017-10-25

Both genetic and infectious diseases can result in skeletal muscle degeneration, inflammation, pain, and/or weakness. Duchenne muscular dystrophy (DMD) is the most common congenital muscle disease. DMD causes progressive muscle wasting due to mutations in Dystrophin. Influenza A and B viruses are frequently associated with muscle complications, especially in children. Infections activate an immune response and immunosuppressant drugs reduce DMD symptoms. These data suggest that the immune system may contribute to muscle pathology. However, roles of the immune response in DMD and Influenza muscle complications are not well understood. Zebrafish with dmd mutations are a well-characterized model in which to study the molecular and cellular mechanisms of DMD pathology. We recently showed that zebrafish can be infected by human Influenza A virus (IAV). Thus, the zebrafish is a powerful system with which to ask questions about the etiology and mechanisms of muscle damage due to genetic and/or infectious diseases. We infected zebrafish with IAV and assayed muscle tissue structure, sarcolemma integrity, cell-extracellular matrix (ECM) attachment, and molecular and cellular markers of inflammation in response to IAV infection alone or in the context of DMD. We find that IAV-infected zebrafish display mild muscle degeneration with sarcolemma damage and compromised ECM adhesion. An innate immune response is elicited in muscle in IAV-infected zebrafish: NFkB signaling is activated, pro-inflammatory cytokine expression is upregulated, and neutrophils localize to sites of muscle damage. IAV-infected dmd mutants display more severe muscle damage than would be expected from an additive effect of dmd mutation and IAV infection, suggesting that muscle damage caused by Dystrophin-deficiency and IAV infection is synergistic. These data demonstrate the importance of preventing IAV infections in individuals with genetic muscle diseases. Elucidating the mechanisms of immune-mediated muscle damage will not only apply to DMD and IAV, but also to other conditions where the immune system, inflammation, and muscle tissue are known to be affected, such as autoimmune diseases, cancer, and aging.

p53-Mediated Cellular Response to DNA Damage in Cells with Replicative Hepatitis B Virus

NASA Astrophysics Data System (ADS)

Puisieux, Alain; Ji, Jingwei; Guillot, Celine; Legros, Yann; Soussi, Thierry; Isselbacher, Kurt; Ozturk, Mehmet

1995-02-01

Wild-type p53 acts as a tumor suppressor gene by protecting cells from deleterious effects of genotoxic agents through the induction of a G_1/S arrest or apoptosis as a response to DNA damage. Transforming proteins of several oncogenic DNA viruses inactivate tumor suppressor activity of p53 by blocking this cellular response. To test whether hepatitis B virus displays a similar effect, we studied the p53-mediated cellular response to DNA damage in 2215 hepatoma cells with replicative hepatitis B virus. We demonstrate that hepatitis B virus replication does not interfere with known cellular functions of p53 protein.

High-speed imaging and small-scale explosive characterization techniques to understand effects of primary blast-induced injury on nerve cell structure and function

NASA Astrophysics Data System (ADS)

Piehler, T.; Banton, R.; Zander, N.; Duckworth, J.; Benjamin, R.; Sparks, R.

2018-01-01

Traumatic brain injury (TBI) is often associated with blast exposure. Even in the absence of penetrating injury or evidence of tissue injury on imaging, blast TBI may trigger a series of neural/glial cellular and functional changes. Unfortunately, the diagnosis and proper treatment of mild traumatic brain injury (mTBI) caused by explosive blast is challenging, as it is not easy to clinically distinguish blast from non-blast TBI on the basis of patient symptoms. Damage to brain tissue, cell, and subcellular structures continues to occur slowly and in a manner undetectable by conventional imaging techniques. The threshold shock impulse levels required to induce damage and the cumulative effects upon multiple exposures are not well characterized. Understanding how functional and structural damage from realistic blast impact at cellular and tissue levels at variable timescales after mTBI events may be vital for understanding this injury phenomenon and for linking mechanically induced structural changes with measurable effects on the nervous system. Our working hypothesis is that there is some transient physiological dysfunction occurring at cellular and subcellular levels within the central nervous system due to primary blast exposure. We have developed a novel in vitro indoor experimental system that uses real military explosive charges to more accurately represent military blast exposure and to probe the effects of primary explosive blast on dissociated neurons. We believe this system offers a controlled experimental method to analyze and characterize primary explosive blast-induced cellular injury and to understand threshold injury phenomenon. This paper will also focus on the modeling aspect of our work and how it relates to the experimental work.

Cervical cancer cells (HeLa) response to photodynamic therapy using a zinc phthalocyanine photosensitizer.

PubMed

Hodgkinson, Natasha; Kruger, Cherie Ann; Mokwena, Mpho; Abrahamse, Heidi

2017-12-01

Cervical cancer is the most common gynecological malignancy worldwide, and the leading cause of cancer related deaths among females. Conventional treatment for early cervical cancer is radical hysterectomy. In locally advanced cancer the treatment of choice is concurrent chemo radiation. Although such treatment methods show promise, they do have adverse side effects. To minimize these effects, as well as prevent cancer re-occurrence, new treatment methods are being investigated. Photodynamic therapy (PDT) involves the selective uptake of a photosensitizer (PS) by cancer cells, illumination with light of an appropriate wavelength that triggers a photochemical reaction leading to the generation of reactive oxygen and subsequent tumor regression. The effect of PDT on a cervical cancer cell line (HeLa) was assessed by exposing cultured cells to a sulphonated zinc phthalocyanine PS (ZnPcS mix ) and irradiating the cells using a 673nm diode laser. The effects were measured using the Trypan blue viability assay, adenosine triphosphate assay (ATP) luminescence assay for proliferation, Lactate Dehydrogenase (LDH) membrane integrity cytotoxicity assay, and fluorescent microscopy to assess PS cellular localization and nuclear damage. Fluorescent microscopy revealed localization of the PS in the cytoplasm and perinuclear region of HeLa cells. PDT treated cellular responses showed dose dependent structural changes, with decreased cell viability and proliferation, as well as considerable membrane damage. Hoechst stained cells also revealed DNA damage in PDT treated cells. The final findings from this study suggest that ZnPcS mix is a promising PS for the PDT treatment of cervical cancer in vitro, where a significant 85% cellular cytotoxicity with only 25% cellular viability was noted in cells which received 1μM ZnPcS mix when an 8J/cm 2 fluence was applied. Copyright © 2017 Elsevier B.V. All rights reserved.

Ageing induced vascular smooth muscle cell senescence in atherosclerosis.

PubMed

Uryga, Anna K; Bennett, Martin R

2016-04-15

Atherosclerosis is a disease of ageing in that its incidence and prevalence increase with age. However, atherosclerosis is also associated with biological ageing, manifest by a number of typical hallmarks of ageing in the atherosclerotic plaque. Thus, accelerated biological ageing may be superimposed on the effects of chronological ageing in atherosclerosis. Tissue ageing is seen in all cells that comprise the plaque, but particularly in vascular smooth muscle cells (VSMCs). Hallmarks of ageing include evidence of cell senescence, DNA damage (including telomere attrition), mitochondrial dysfunction, a pro-inflammatory secretory phenotype, defects in proteostasis, epigenetic changes, deregulated nutrient sensing, and exhaustion of progenitor cells. In this model, initial damage to DNA (genomic, telomeric, mitochondrial and epigenetic changes) results in a number of cellular responses (cellular senescence, deregulated nutrient sensing and defects in proteostasis). Ultimately, ongoing damage and attempts at repair by continued proliferation overwhelm reparative capacity, causing loss of specialised cell functions, cell death and inflammation. This review summarises the evidence for accelerated biological ageing in atherosclerosis, the functional consequences of cell ageing on cells comprising the plaque, and the causal role that VSMC senescence plays in atherogenesis. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

The role of the immune system in central nervous system plasticity after acute injury.

PubMed

Peruzzotti-Jametti, Luca; Donegá, Matteo; Giusto, Elena; Mallucci, Giulia; Marchetti, Bianca; Pluchino, Stefano

2014-12-26

Acute brain injuries cause rapid cell death that activates bidirectional crosstalk between the injured brain and the immune system. In the acute phase, the damaged CNS activates resident and circulating immune cells via the local and systemic release of soluble mediators. This early immune activation is necessary to confine the injured tissue and foster the clearance of cellular debris, thus bringing the inflammatory reaction to a close. In the chronic phase, a sustained immune activation has been described in many CNS disorders, and the degree of this prolonged response has variable effects on spontaneous brain regenerative processes. The challenge for treating acute CNS damage is to understand how to optimally engage and modify these immune responses, thus providing new strategies that will compensate for tissue lost to injury. Herein we have reviewed the available information regarding the role and function of the innate and adaptive immune responses in influencing CNS plasticity during the acute and chronic phases of after injury. We have examined how CNS damage evolves along the activation of main cellular and molecular pathways that are associated with intrinsic repair, neuronal functional plasticity and facilitation of tissue reorganization. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

SMC1-Mediated Intra-S-Phase Arrest Facilitates Bocavirus DNA Replication

PubMed Central

Luo, Yong; Deng, Xuefeng; Cheng, Fang; Li, Yi

2013-01-01

Activation of a host DNA damage response (DDR) is essential for DNA replication of minute virus of canines (MVC), a member of the genus Bocavirus of the Parvoviridae family; however, the mechanism by which DDR contributes to viral DNA replication is unknown. In the current study, we demonstrate that MVC infection triggers the intra-S-phase arrest to slow down host cellular DNA replication and to recruit cellular DNA replication factors for viral DNA replication. The intra-S-phase arrest is regulated by ATM (ataxia telangiectasia-mutated kinase) signaling in a p53-independent manner. Moreover, we demonstrate that SMC1 (structural maintenance of chromosomes 1) is the key regulator of the intra-S-phase arrest induced during infection. Either knockdown of SMC1 or complementation with a dominant negative SMC1 mutant blocks both the intra-S-phase arrest and viral DNA replication. Finally, we show that the intra-S-phase arrest induced during MVC infection was caused neither by damaged host cellular DNA nor by viral proteins but by replicating viral genomes physically associated with the DNA damage sensor, the Mre11-Rad50-Nbs1 (MRN) complex. In conclusion, the feedback loop between MVC DNA replication and the intra-S-phase arrest is mediated by ATM-SMC1 signaling and plays a critical role in MVC DNA replication. Thus, our findings unravel the mechanism underlying DDR signaling-facilitated MVC DNA replication and demonstrate a novel strategy of DNA virus-host interaction. PMID:23365434

Utility of DF-1 for Radioprotection in Lymphocytes

NASA Technical Reports Server (NTRS)

Reynolds, Julia; Casey, Rachael; Wu, Honglu; Huff, Janice; Emami, Kamal; Moore, Valerie; Jeevarajan, Antony

2007-01-01

The development of degenerative changes in the vasculature, such as atherosclerosis, is a known consequence of exposure to ionizing radiation, and is thus a concern for astronaut health following long duration space flight. Cellular damage caused by radiation is due to free radical generation and DNA damage. The goal of this project was to assess the ability of a C60-derivative, DF-1, to mitigate cellular damage resulting from radiation exposure in primary human lymphocytes. DF-1 is a water-soluble C60 fullerene encapsulated in dendrimeric functional groups that is proposed to exhibit antioxidant properties. Human lymphocytes are radiosensitive and travel throughout the body potentially causing bystander effects in any tissues they contact. These cells were subjected to varying doses of gamma radiation in the presence or absence of DF-1. Cells were collected at 48 hours post-irradiation for chromosomal aberration studies and at 72 hours post-irradiation for micronuclei studies. These studies showed that the irradiated cells contained more chromosomal aberrations and micronuclei than the control cells. Addition of the DF-1 reduced the amount of observed DNA damage in the irradiated cells. Growth curves were measured for the lymphocytes exposed to 0 and 4 Gray gamma irradiations, and we observed less growth in the cells irradiated at 4 Gy. 2,7-dichlorofluorescein diacetate was used to detect reactive oxygen species production, and increased production of ROS was observed in the irradiated lymphocytes. Human lymphocytes were subjected to varying doses of gamma or photon radiation in the presence and absence of DF-1 and a known radioprotectant, amifostine. After irradiation, the production of reactive oxygen species, growth curves and cell viability were measured. These cells were also collected to quantify chromosomal aberrations and micronuclei formation. We predict that irradiated cells will show the most damage and that DF-1 will provide protective effects similar to those of amifostine, an established radioprotectant.

[Pulse-modulated Electromagnetic Radiation of Extremely High Frequencies Protects Cellular DNA against Damaging Effect of Physico-Chemical Factors in vitro].

PubMed

Gapeyev, A B; Lukyanova, N A

2015-01-01

Using a comet assay technique, we investigated protective effects of. extremely high frequency electromagnetic radiation in combination with the damaging effect of X-ray irradiation, the effect of damaging agents hydrogen peroxide and methyl methanesulfonate on DNA in mouse whole blood leukocytes. It was shown that the preliminary exposure of the cells to low intensity pulse-modulated electromagnetic radiation (42.2 GHz, 0.1 mW/cm2, 20-min exposure, modulation frequencies of 1 and 16 Hz) caused protective effects decreasing the DNA damage by 20-45%. The efficacy of pulse-modulated electromagnetic radiation depended on the type of genotoxic agent and increased in a row methyl methanesulfonate--X-rays--hydrogen peroxide. Continuous electromagnetic radiation was ineffective. The mechanisms of protective effects may be connected with an induction of the adaptive response by nanomolar concentrations of reactive oxygen species formed by pulse-modulated electromagnetic radiation.

Membrane permeability and the loss of germination factor from Neurospora crassa at low water activities

NASA Technical Reports Server (NTRS)

Charlang, G.; Horowitz, N. H.

1974-01-01

Neurospora crassa conidia incubating in buffer at low water activities release a germination-essential component as well as 260-nm absorbing and ninhydrin-positive materials, regardless of whether an electrolyte or nonelectrolyte is used to reduce water activity. Chloroform and antibiotics known to increase cell-membrane permeability have a similar effect. This suggests that membrane damage occurs in media of low water activity and that an increase in permeability is responsible for the release of cellular components. The damage caused in media of low water activity is nonlethal in most cases, and the conidia recover when transferred to nutrient medium.

Characterisation of Growth and Ultrastructural Effects of the Xanthoria elegans Photobiont After 1.5 Years of Space Exposure on the International Space Station

NASA Astrophysics Data System (ADS)

Brandt, Annette; Posthoff, Eva; de Vera, Jean-Pierre; Onofri, Silvano; Ott, Sieglinde

2016-06-01

The lichen Xanthoria elegans has been exposed to space and simulated Mars-analogue environment in the Lichen and Fungi Experiment (LIFE) on the EXPOSE-E facility at the International Space Station (ISS). This long-term exposure of 559 days tested the ability of various organisms to cope with either low earth orbit (LEO) or Mars-analogue conditions, such as vacuum, Mars-analogue atmosphere, rapid temperature cycling, cosmic radiation of up to 215 ± 16 mGy, and insolation of accumulated doses up to 4.87 GJm-2, including up to 0.314 GJm-2 of UV irradiation. In a previous study, X. elegans demonstrated considerable resistance towards these conditions by means of photosynthetic activity as well as by post-exposure metabolic activity of 50-80 % in the algal and 60-90 % in the fungal symbiont (Brandt et al. Int J Astrobiol 14(3):411-425, 2015). The two objectives of the present study were complementary: First, to verify the high post-exposure viability by using a qualitative cultivation assay. Second, to characterise the cellular damages by transmission electron microscopy (TEM) which were caused by the space and Mars-analogue exposure conditions of LIFE. Since the algal symbiont of lichens is considered as the more susceptible partner (de Vera and Ott 2010), the analyses focused on the photobiont. The study demonstrated growth and proliferation of the isolated photobiont after all exposure conditions of LIFE. The ultrastructural analysis of the algal cells provided an insight to cellular damages caused by long-term exposure and highlighted that desiccation-induced breakdown of cellular integrity is more pronounced under the more severe space vacuum than under Mars-analogue atmospheric conditions. In conclusion, desiccation-induced damages were identified as a major threat to the photobiont of X. elegans. Nonetheless, a fraction of the photobiont cells remained cultivable after all exposure conditions tested in LIFE.

Goat milk with and without increased concentrations of lysozyme improves repair of intestinal cell damage induced by enteroaggregative Escherichia coli.

PubMed

Carvalho, Eunice B; Maga, Elizabeth A; Quetz, Josiane S; Lima, Ila F N; Magalhães, Hemerson Y F; Rodrigues, Felipe A R; Silva, Antônio V A; Prata, Mara M G; Cavalcante, Paloma A; Havt, Alexandre; Bertolini, Marcelo; Bertolini, Luciana R; Lima, Aldo A M

2012-08-11

Enteroaggregative Escherichia coli (EAEC) causes diarrhea, malnutrition and poor growth in children. Human breast milk decreases disease-causing bacteria by supplying nutrients and antimicrobial factors such as lysozyme. Goat milk with and without human lysozyme (HLZ) may improve the repair of intestinal barrier function damage induced by EAEC. This work investigates the effect of the milks on intestinal barrier function repair, bacterial adherence in Caco-2 and HEp-2 cells, intestinal cell proliferation, migration, viability and apoptosis in IEC-6 cells in the absence or presence of EAEC. Rat intestinal epithelial cells (IEC-6, ATCC, Rockville, MD) were used for proliferation, migration and viability assays and human colon adenocarcinoma (Caco-2, ATCC, Rockville, MD) and human larynx carcinoma (HEp-2, ATCC, Rockville, MD) cells were used for bacterial adhesion assays. Goats expressing HLZ in their milk were generated and express HLZ in milk at concentration of 270 μg/ml. Cells were incubated with pasteurized milk from either transgenic goats expressing HLZ or non-transgenic control goats in the presence and absence of EAEC strain 042 (O44:H18). Cellular proliferation was significantly greater in the presence of both HLZ transgenic and control goat milk compared to cells with no milk. Cellular migration was significantly decreased in the presence of EAEC alone but was restored in the presence of milk. Milk from HLZ transgenic goats had significantly more migration compared to control milk. Both milks significantly reduced EAEC adhesion to Caco-2 cells and transgenic milk resulted in less colonization than control milk using a HEp-2 assay. Both milks had significantly increased cellular viability as well as less apoptosis in both the absence and presence of EAEC. These data demonstrated that goat milk is able to repair intestinal barrier function damage induced by EAEC and that goat milk with a higher concentration of lysozyme offers additional protection.

Characterisation of Growth and Ultrastructural Effects of the Xanthoria elegans Photobiont After 1.5 Years of Space Exposure on the International Space Station.

PubMed

Brandt, Annette; Posthoff, Eva; de Vera, Jean-Pierre; Onofri, Silvano; Ott, Sieglinde

2016-06-01

The lichen Xanthoria elegans has been exposed to space and simulated Mars-analogue environment in the Lichen and Fungi Experiment (LIFE) on the EXPOSE-E facility at the International Space Station (ISS). This long-term exposure of 559 days tested the ability of various organisms to cope with either low earth orbit (LEO) or Mars-analogue conditions, such as vacuum, Mars-analogue atmosphere, rapid temperature cycling, cosmic radiation of up to 215 ± 16 mGy, and insolation of accumulated doses up to 4.87 GJm(-2), including up to 0.314 GJm(-2) of UV irradiation. In a previous study, X. elegans demonstrated considerable resistance towards these conditions by means of photosynthetic activity as well as by post-exposure metabolic activity of 50-80% in the algal and 60-90% in the fungal symbiont (Brandt et al. Int J Astrobiol 14(3):411-425, 2015). The two objectives of the present study were complementary: First, to verify the high post-exposure viability by using a qualitative cultivation assay. Second, to characterise the cellular damages by transmission electron microscopy (TEM) which were caused by the space and Mars-analogue exposure conditions of LIFE. Since the algal symbiont of lichens is considered as the more susceptible partner (de Vera and Ott 2010), the analyses focused on the photobiont. The study demonstrated growth and proliferation of the isolated photobiont after all exposure conditions of LIFE. The ultrastructural analysis of the algal cells provided an insight to cellular damages caused by long-term exposure and highlighted that desiccation-induced breakdown of cellular integrity is more pronounced under the more severe space vacuum than under Mars-analogue atmospheric conditions. In conclusion, desiccation-induced damages were identified as a major threat to the photobiont of X. elegans. Nonetheless, a fraction of the photobiont cells remained cultivable after all exposure conditions tested in LIFE.

Eccentric localization of catalase to protect chromosomes from oxidative damages during meiotic maturation in mouse oocytes.

PubMed

Park, Yong Seok; You, Seung Yeop; Cho, Sungrae; Jeon, Hyuk-Joon; Lee, Sukchan; Cho, Dong-Hyung; Kim, Jae-Sung; Oh, Jeong Su

2016-09-01

The maintenance of genomic integrity and stability is essential for the survival of every organism. Unfortunately, DNA is vulnerable to attack by a variety of damaging agents. Oxidative stress is a major cause of DNA damage because reactive oxygen species (ROS) are produced as by-products of normal cellular metabolism. Cells have developed eloquent antioxidant defense systems to protect themselves from oxidative damage along with aerobic metabolism. Here, we show that catalase (CAT) is present in mouse oocytes to protect the genome from oxidative damage during meiotic maturation. CAT was expressed in the nucleus to form unique vesicular structures. However, after nuclear envelope breakdown, CAT was redistributed in the cytoplasm with particular focus at the chromosomes. Inhibition of CAT activity increased endogenous ROS levels, but did not perturb meiotic maturation. In addition, CAT inhibition produced chromosomal defects, including chromosome misalignment and DNA damage. Therefore, our data suggest that CAT is required not only to scavenge ROS, but also to protect DNA from oxidative damage during meiotic maturation in mouse oocytes.

Mitochondrial dysfunction as a trigger of innate immune responses and inflammation.

PubMed

West, A Phillip

2017-11-01

A growing literature indicates that mitochondria are key participants in innate immune pathways, functioning as both signaling platforms and contributing to effector responses. In addition to regulating antiviral signaling and antibacterial immunity, mitochondria are also important drivers of inflammation caused by sterile injury. Much research on mitochondrial control of immunity now centers on understanding how mitochondrial constituents released during cellular damage simulate the innate immune system. When mitochondrial integrity is compromised, mitochondrial damage-associated molecular patterns engage pattern recognition receptors, trigger inflammation, and promote pathology in an expanding list of diseases. Here, I review the emerging knowledge of mitochondrial dysfunction in innate immune responses and discuss how environmental exposures may induce mitochondrial damage to potentiate inflammation and human disease. Copyright © 2017 Elsevier B.V. All rights reserved.

The osmotic/calcium stress theory of brain damage: are free radicals involved?

PubMed

Pazdernik, T L; Layton, M; Nelson, S R; Samson, F E

1992-01-01

This overview presents data showing that glucose use increases and that excitatory amino acids (i.e., glutamate, aspartate), taurine and ascorbate increase in the extracellular fluid during seizures. During the cellular hyperactive state taurine appears to serve as an osmoregulator and ascorbate may serve as either an antioxidant or as a pro-oxidant. Finally, a unifying hypothesis is given for seizure-induced brain damage. This unifying hypothesis states that during seizures there is a release of excitatory amino acids which act on glutamatergic receptors, increasing neuronal activity and thereby increasing glucose use. This hyperactivity of cells causes an influx of calcium (i.e., calcium stress) and water movements (i.e., osmotic stress) into the cells that culminate in brain damage mediated by reactive oxygen species.

Honest sexual signalling mediated by parasite and testosterone effects on oxidative balance.

PubMed

Mougeot, Francois; Martínez-Padilla, Jesús; Webster, Lucy M I; Blount, Jonathan D; Pérez-Rodríguez, Lorenzo; Piertney, Stuart B

2009-03-22

Extravagant ornaments evolved to advertise their bearers' quality, the honesty of the signal being ensured by the cost paid to produce or maintain it. The oxidation handicap hypothesis (OHH) proposes that a main cost of testosterone-dependent ornamentation is oxidative stress, a condition whereby the production of reactive oxygen and nitrogen species (ROS/RNS) overwhelms the capacity of antioxidant defences. ROS/RNS are unstable, very reactive by-products of normal metabolic processes that can cause extensive damage to key biomolecules (cellular proteins, lipids and DNA). Oxidative stress has been implicated in the aetiology of many diseases and could link ornamentation and genetic variation in fitness-related traits. We tested the OHH in a free-living bird, the red grouse. We show that elevated testosterone enhanced ornamentation and increased circulating antioxidant levels, but caused oxidative damage. Males with smaller ornaments suffered more oxidative damage than those with larger ornaments when forced to increase testosterone levels, consistent with a handicap mechanism. Parasites depleted antioxidant defences, caused oxidative damage and reduced ornament expression. Oxidative damage extent and the ability of males to increase antioxidant defences also explained the impacts of testosterone and parasites on ornamentation within treatment groups. Because oxidative stress is intimately linked to immune function, parasite resistance and fitness, it provides a reliable currency in the trade-off between individual health and ornamentation. The costs induced by oxidative stress can apply to a wide range of signals, which are testosterone-dependent or coloured by pigments with antioxidant properties.

Honest sexual signalling mediated by parasite and testosterone effects on oxidative balance

PubMed Central

Mougeot, Francois; Martínez-Padilla, Jesu´s; Webster, Lucy M.I.; Blount, Jonathan D.; Pérez-Rodríguez, Lorenzo; Piertney, Stuart B.

2008-01-01

Extravagant ornaments evolved to advertise their bearers' quality, the honesty of the signal being ensured by the cost paid to produce or maintain it. The oxidation handicap hypothesis (OHH) proposes that a main cost of testosterone-dependent ornamentation is oxidative stress, a condition whereby the production of reactive oxygen and nitrogen species (ROS/RNS) overwhelms the capacity of antioxidant defences. ROS/RNS are unstable, very reactive by-products of normal metabolic processes that can cause extensive damage to key biomolecules (cellular proteins, lipids and DNA). Oxidative stress has been implicated in the aetiology of many diseases and could link ornamentation and genetic variation in fitness-related traits. We tested the OHH in a free-living bird, the red grouse. We show that elevated testosterone enhanced ornamentation and increased circulating antioxidant levels, but caused oxidative damage. Males with smaller ornaments suffered more oxidative damage than those with larger ornaments when forced to increase testosterone levels, consistent with a handicap mechanism. Parasites depleted antioxidant defences, caused oxidative damage and reduced ornament expression. Oxidative damage extent and the ability of males to increase antioxidant defences also explained the impacts of testosterone and parasites on ornamentation within treatment groups. Because oxidative stress is intimately linked to immune function, parasite resistance and fitness, it provides a reliable currency in the trade-off between individual health and ornamentation. The costs induced by oxidative stress can apply to a wide range of signals, which are testosterone-dependent or coloured by pigments with antioxidant properties. PMID:19129122

Methamphetamine- and Trauma-Induced Brain Injuries: Comparative Cellular and Molecular Neurobiological Substrates

PubMed Central

Gold, Mark S.; Kobeissy, Firas H.; Wang, Kevin K.W.; Merlo, Lisa J.; Bruijnzeel, Adriaan W.; Krasnova, Irina N.; Cadet, Jean Lud

2009-01-01

The use of methamphetamine (METH) is a growing public health problem because its abuse is associated with long-term biochemical and structural effects on the human brain. Neurodegeneration is often observed in humans as a result of mechanical injuries (e.g. traumatic brain injury, TBI) and ischemic damage (strokes). In this review, we discuss recent findings documenting the fact that the psychostimulant drug, METH, can cause neuronal damage in several brain regions. The accumulated evidence from our laboratories and those of other investigators indicates that acute administration of METH leads to activation of calpain and caspase proteolytic systems. These systems are also involved in causing neuronal damage secondary to traumatic and ischemic brain injuries. Protease activation is accompanied by proteolysis of endogenous neuronal structural proteins (αII-spectrin and MAP-tau protein) evidenced by the appearance of their breakdown products after these injuries. When taken together, these observations suggest that METH exposure, like TBI, can cause substantial damage to the brain by causing both apoptotic and necrotic cell death in the brains of METH addicts who use large doses of the drug during their lifetimes. Finally, because METH abuse is accompanied by functional and structural changes in the brain similar to those in TBI, METH addicts might experience greater benefit if their treatment involved greater emphasis on rehabilitation in conjunction with the use of potential neuroprotective pharmacological agents such as calpain and caspase inhibitors similar to those used in TBI. PMID:19345341

Patients referred to an indoor air health clinic: exposure to water-damaged buildings causes an increase of lymphocytes in bronchoalveolar lavage and a decrease of CD19 leucocytes in peripheral blood.

PubMed

Wolff, Henrik; Mussalo-Rauhamaa, Helena; Raitio, Hanna; Elg, Peter; Orpana, Arto; Piilonen, Anneli; Haahtela, Tari

2009-01-01

Respiratory and other symptoms are often associated with exposure to microbes present in water-damaged buildings. We examined 82 consecutive patients referred to the Indoor Air Clinic, Helsinki University Hospital, due to symptoms suspected of having been caused by long-term exposure to water damage in the home or workplace. Exposure to water damage was assessed by building inspections and microbial analyses as needed. Bronchoalveolar lavage, lung function measurements, skin prick tests to inhalant allergens and radiological examinations were performed in all patients. Leucocyte subsets in peripheral blood were analysed in 35 patients. Marked water damage was detected in the homes or workplaces of 47 (59%) patients; the remaining 34 patients formed the control group. The exposed group expressed more symptoms in total than the control group: fatigue, conjunctival symptoms, rhinitis with sinusitis, recurrent bronchitis and asthma were more common in the exposed group, but a significant difference was seen only for headache. In BAL (bronchoalveolar lavage) samples, lymphocytes represented 25% of the total cell population in non-smoking-exposed patients compared with 12% in control patients (p=0.004). In peripheral blood, CD19 leucocytes were significantly decreased in the exposed group (7.5% versus 12.3%; p<0.01). Confirmed exposure to water damage was associated with an increase in symptoms. Exposure to water damage caused a significant change in the cellular composition in BAL fluid (lymphocytosis) and blood (decrease of CD19 cells). The depletion of CD19 leucocytes in peripheral blood may indicate an active immune response in the lungs.

Substance P promotes the recovery of oxidative stress-damaged retinal pigmented epithelial cells by modulating Akt/GSK-3β signaling.

PubMed

Baek, Sang-Min; Yu, Seung-Young; Son, Youngsook; Hong, Hyun Sook

2016-01-01

Senescence of the retina causes an accumulation of reactive oxygen species (ROS). Oxidative stress associated with ROS can damage RPE cells, leading to neovascularization and severe ocular disorders, including age-related macular degeneration (AMD). Thus, the early treatment of the damage caused by oxidative stress is critical for preventing the development of ocular diseases such as AMD. In this study, we examined the role of substance P (SP) in the recovery of RPE cells damaged by oxidative stress. To induce oxidative stress, RPE cells were treated with H2O2 at various doses. Recovery from oxidative stress was studied following treatment with SP by analyzing cell viability, cell proliferation, cell apoptosis, and Akt/glycogen synthase kinase (GSK)-3β activation in RPE cells in vitro. H2O2 treatment reduced cellular viability in a dose-dependent manner. SP inhibited the reduction of cell viability due to H2O2 and caused increased cell proliferation and decreased cell apoptosis. Cell survival under oxidative stress requires the activation of Akt signaling that enables cells to resist oxidative stress-induced damage. SP treatment activated Akt/GSK-3β signaling in RPE cells, which were damaged due to oxidative stress, and the inhibition of Akt signaling in SP-treated RPE cells prevented SP-induced recovery. Pretreatment with the neurokinin 1 receptor (NK1R) antagonist reduced the recovery effect of SP on damaged RPE cells. SP can protect RPE cells from oxidant-induced cell death by activating Akt/GSK-3β signaling via NK1R. This study suggests the possibility of SP as a treatment for oxidative stress-related diseases.

Quantitation of Radiation Induced Deletion and Recombination Events Associated with Repeated DNA Sequences

NASA Technical Reports Server (NTRS)

Sinden, Richard R.

1999-01-01

Manned exploration of space exposes the explorers to a complex and novel radiation environment. The galactic cosmic ray and trapped belt radiation (predominantly proton) components of this environment are relatively constant, and the variations with the solar cycle are well understood and predictable. The level of radiation encountered in low earth orbits is determined by several factors, including altitude, inclination of orbit with respect to the equator, and spacecraft shielding. At higher altitudes, and on a Mars mission, the level of radiation exposure will increase significantly. A significant fraction of the dose may be delivered by solar particle events which vary dramatically in dose rate and incident particle spectrum. High-LET radiation is of particular concern. High-LET radiation, a component of galactic cosmic rays (GCR), is comprised of a variety of charged particles of various energies (10 MeV/n to 10 GeV/n), including about 87% photons, 12% helium ions, and heavy ions (including iron). These high energy particles can cause significant damage to target cells. The different particle types and energies result in different patterns of energy deposition at the molecular and cellular level in a primary target cell. They can also cause significant damage to other, nearby cells as a result of secondary particles. Protons, for instance produce secondaries that include photons, neutrons, pions, heavy particles, as well as gamma rays. Heavy ions deposit energy in a "track" in which the magnitude of the damage varies as the particle loses energy. Heavy ions produce secondary delta rays, or electrons. The distribution of damage through tissue is described by a Bragg curve which will be characteristic for different energies. Needless to say there are differences in the RBE of protons and a particles. High-LET heavy ions are particularly damaging to cells as they do continual damage throughout their track. Differences in these energy deposition patterns can significantly influence the nature of DNA damage and the ability of cellular systems to repair such damage. It has been suspected that these differences also affect the spatial distribution of damage within the DNA of the interphase cell nucleus and produce corresponding differences in endpoints related to health effects. The interaction of a single high-LET particle with chromatin has been suggested to cause multiple double strand breaks within a relatively short distance. In part this is due to the organization of DNA into chromatin fibers in which distant regions of the DNA helix can be physically juxtaposed by the various levels of coiling of the DNA. This prediction was confirmed by the detection of the generation of double strand DNA fragments of 100-2000 bp following exposure to high-LET ions (including iron).

Pink1 and Parkin regulate Drosophila intestinal stem cell proliferation during stress and aging.

PubMed

Koehler, Christopher L; Perkins, Guy A; Ellisman, Mark H; Jones, D Leanne

2017-08-07

Intestinal stem cells (ISCs) maintain the midgut epithelium in Drosophila melanogaster Proper cellular turnover and tissue function rely on tightly regulated rates of ISC division and appropriate differentiation of daughter cells. However, aging and epithelial injury cause elevated ISC proliferation and decreased capacity for terminal differentiation of daughter enteroblasts (EBs). The mechanisms causing functional decline of stem cells with age remain elusive; however, recent findings suggest that stem cell metabolism plays an important role in the regulation of stem cell activity. Here, we investigate how alterations in mitochondrial homeostasis modulate stem cell behavior in vivo via RNA interference-mediated knockdown of factors involved in mitochondrial dynamics. ISC/EB-specific knockdown of the mitophagy-related genes Pink1 or Parkin suppresses the age-related loss of tissue homeostasis, despite dramatic changes in mitochondrial ultrastructure and mitochondrial damage in ISCs/EBs. Maintenance of tissue homeostasis upon reduction of Pink1 or Parkin appears to result from reduction of age- and stress-induced ISC proliferation, in part, through induction of ISC senescence. Our results indicate an uncoupling of cellular, tissue, and organismal aging through inhibition of ISC proliferation and provide insight into strategies used by stem cells to maintain tissue homeostasis despite severe damage to organelles. © 2017 Koehler et al.

Suppression of E. multilocularis Hydatid Cysts after Ionizing Radiation Exposure

PubMed Central

Zhou, Rong; Zhang, Hong

2013-01-01

Background Heavy-ion therapy has an advantage over conventional radiotherapy due to its superb biological effectiveness and dose conformity in cancer therapy. It could be a potential alternate approach for hydatid cyst treatment. However, there is no information currently available on the cellular and molecular basis for heavy-ion irradiation induced cell death in cystic echinococcosis. Methododology/Principal Findings LD50 was scored by protoscolex death. Cellular and ultrastructural changes within the parasite were studied by light and electron microscopy, mitochondrial DNA (mtDNA) damage and copy number were measured by QPCR, and apoptosis was determined by caspase 3 expression and caspase 3 activity. Ionizing radiation induced sparse cytoplasm, disorganized and clumped organelles, large vacuoles and devoid of villi. The initial mtDNA damage caused by ionizing radiation increased in a dose-dependent manner. The kinetic of DNA repair was slower after carbon-ion radiation than that after X-rays radiation. High dose carbon-ion radiation caused irreversible mtDNA degradation. Cysts apoptosis was pronounced after radiation. Carbon-ion radiation was more effective to suppress hydatid cysts than X-rays. Conclusions These studies provide a framework to the evaluation of attenuation effect of heavy-ion radiation on cystic echinococcosis in vitro. Carbon-ion radiation is more effective to suppress E. multilocularis than X-rays. PMID:24205427

Glycerophospholipid Profiles of Bats with White-Nose Syndrome.

PubMed

Pannkuk, Evan L; McGuire, Liam P; Warnecke, Lisa; Turner, James M; Willis, Craig K R; Risch, Thomas S

2015-01-01

Pseudogymnoascus destructans is an ascomycetous fungus responsible for the disease dubbed white-nose syndrome (WNS) and massive mortalities of cave-dwelling bats. The fungus infects bat epidermal tissue, causing damage to integumentary cells and pilosebaceous units. Differences in epidermal lipid composition caused by P. destructans infection could have drastic consequences for a variety of physiological functions, including innate immune efficiency and water retention. While bat surface lipid and stratum corneum lipid composition have been described, the differences in epidermal lipid content between healthy tissue and P. destructans-infected tissue have not been documented. In this study, we analyzed the effect of wing damage from P. destructans infection on the epidermal polar lipid composition (glycerophospholipids [GPs] and sphingomyelin) of little brown bats (Myotis lucifugus). We hypothesized that infection would lead to lower levels of total lipid or higher oxidized lipid product proportions. Polar lipids from three damaged and three healthy wing samples were profiled by electrospray ionization tandem mass spectrometry. We found lower total broad lipid levels in damaged tissue, specifically ether-linked phospholipids, lysophospholipids, phosphatidylcholine, and phosphatidylethanolamine. Thirteen individual GP species from four broad GP classes were present in higher amounts in healthy tissue. Six unsaturated GP species were absent in damaged tissue. Our results confirm that P. destructans infection leads to altered lipid profiles. Clinical signs of WNS may include lower lipid levels and lower proportions of unsaturated lipids due to cellular and glandular damage.

Inhibition of Transforming Growth Factor-Beta1 SignalingAttenuates Ataxia Telangiectasia Mutated Activity in Response toGenotoxic Stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirshner, Julia; Jobling, Michael F.; Pajares, Maria Jose

2006-01-01

Ionizing radiation causes DNA damage that elicits a cellular program of damage control coordinated by the kinase activity of ataxia telangiectasia mutated protein (ATM). Transforming growth factor {beta} (TGF{beta})-1, which is activated by radiation, is a potent and pleiotropic mediator of physiologic and pathologic processes. Here we show that TGF{beta} inhibition impedes the canonical cellular DNA damage stress response. Irradiated Tgf{beta}I null murine epithelial cells or human epithelial cells treated with a small-molecule inhibitor of TGF{beta} type I receptor kinase exhibit decreased phosphorylation of Chk2, Rad17, and p53; reduced H2AX radiation-induced foci; and increased radiosensitivity compared with TGF{beta} competent cells.more » We determined that loss of TGF{beta} signaling in epithelial cells truncated ATM autophosphorylation and significantly reduced its kinase activity, without affecting protein abundance. Addition of TGF{beta} restored functional ATM and downstream DNA damage responses. These data reveal a heretofore undetected critical link between the microenvironment and ATM, which directs epithelial cell stress responses, cell fate, and tissue integrity. Thus, Tgf{beta}I, in addition to its role in homoeostatic growth control, plays a complex role in regulating responses to genotoxic stress, the failure of which would contribute to the development of cancer; conversely, inhibiting TGF{beta} may be used to advantage in cancer therapy.« less

The Role of Oxidative Stress in Parkinson’s Disease

PubMed Central

Dias, Vera; Junn, Eunsung; Mouradian, M. Maral

2014-01-01

Oxidative stress plays an important role in the degeneration of dopaminergic neurons in Parkinson’s disease (PD). Disruptions in the physiologic maintenance of the redox potential in neurons interfere with several biological processes, ultimately leading to cell death. Evidence has been developed for oxidative and nitrative damage to key cellular components in the PD substantia nigra. A number of sources and mechanisms for the generation of reactive oxygen species (ROS) are recognized including the metabolism of dopamine itself, mitochondrial dysfunction, iron, neuroinflammatory cells, calcium, and aging. PD causing gene products including DJ-1, PINK1, parkin, alpha-synuclein and LRRK2 also impact in complex ways mitochondrial function leading to exacerbation of ROS generation and susceptibility to oxidative stress. Additionally, cellular homeostatic processes including the ubiquitin-proteasome system and mitophagy are impacted by oxidative stress. It is apparent that the interplay between these various mechanisms contributes to neurodegeneration in PD as a feed forward scenario where primary insults lead to oxidative stress, which damages key cellular pathogenetic proteins that in turn cause more ROS production. Animal models of PD have yielded some insights into the molecular pathways of neuronal degeneration and highlighted previously unknown mechanisms by which oxidative stress contributes to PD. However, therapeutic attempts to target the general state of oxidative stress in clinical trials have failed to demonstrate an impact on disease progression. Recent knowledge gained about the specific mechanisms related to PD gene products that modulate ROS production and the response of neurons to stress may provide targeted new approaches towards neuroprotection. PMID:24252804

Mobile phone specific electromagnetic fields induce transient DNA damage and nucleotide excision repair in serum-deprived human glioblastoma cells.

PubMed

Al-Serori, Halh; Ferk, Franziska; Kundi, Michael; Bileck, Andrea; Gerner, Christopher; Mišík, Miroslav; Nersesyan, Armen; Waldherr, Monika; Murbach, Manuel; Lah, Tamara T; Herold-Mende, Christel; Collins, Andrew R; Knasmüller, Siegfried

2018-01-01

Some epidemiological studies indicate that the use of mobile phones causes cancer in humans (in particular glioblastomas). It is known that DNA damage plays a key role in malignant transformation; therefore, we investigated the impact of the UMTS signal which is widely used in mobile telecommunications, on DNA stability in ten different human cell lines (six brain derived cell lines, lymphocytes, fibroblasts, liver and buccal tissue derived cells) under conditions relevant for users (SAR 0.25 to 1.00 W/kg). We found no evidence for induction of damage in single cell gel electrophoresis assays when the cells were cultivated with serum. However, clear positive effects were seen in a p53 proficient glioblastoma line (U87) when the cells were grown under serum free conditions, while no effects were found in p53 deficient glioblastoma cells (U251). Further experiments showed that the damage disappears rapidly in U87 and that exposure induced nucleotide excision repair (NER) and does not cause double strand breaks (DSBs). The observation of NER induction is supported by results of a proteome analysis indicating that several proteins involved in NER are up-regulated after exposure to UMTS; additionally, we found limited evidence for the activation of the γ-interferon pathway. The present findings show that the signal causes transient genetic instability in glioma derived cells and activates cellular defense systems.

An Update on Oxidative Damage to Spermatozoa and Oocytes.

PubMed

Opuwari, Chinyerum S; Henkel, Ralf R

2016-01-01

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization.

An Update on Oxidative Damage to Spermatozoa and Oocytes

PubMed Central

Opuwari, Chinyerum S.; Henkel, Ralf R.

2016-01-01

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization. PMID:26942204

Transcriptional upregulation of p19INK4d upon diverse genotoxic stress is critical for optimal DNA damage response.

PubMed

Ceruti, Julieta M; Scassa, María E; Marazita, Mariela C; Carcagno, Abel C; Sirkin, Pablo F; Cánepa, Eduardo T

2009-06-01

p19INK4d promotes survival of several cell lines after UV irradiation due to enhanced DNA repair, independently of CDK4 inhibition. To further understand the action of p19INK4d in the cellular response to DNA damage, we aimed to elucidate whether this novel regulator plays a role only in mechanisms triggered by UV or participates in diverse mechanisms initiated by different genotoxics. We found that p19INK4d is induced in cells injured with cisplatin or beta-amyloid peptide as robustly as with UV. The mentioned genotoxics transcriptionally activate p19INK4d expression as demonstrated by run-on assay without influencing its mRNA stability and with partial requirement of protein synthesis. It is not currently known whether DNA damage-inducible genes are turned on by the DNA damage itself or by the consequences of that damage. Experiments carried out in cells transfected with distinct damaged DNA structures revealed that the damage itself is not responsible for the observed up-regulation. It is also not known whether the increased expression of DNA-damage-inducible genes is related to immediate protective responses such as DNA repair or to more delayed responses such as cell cycle arrest or apoptosis. We found that ectopic expression of p19INK4d improves DNA repair ability and protects neuroblastoma cells from apoptosis caused by cisplatin or beta-amyloid peptide. Using clonal cell lines where p19INK4d levels can be modified at will, we show that p19INK4d expression correlates with increased survival and clonogenicity. The results presented here, prompted us to suggest that p19INK4d displays an important role in an early stage of cellular DNA damage response.

Intermediate frequency magnetic field generated by a wireless power transmission device does not cause genotoxicity in vitro.

PubMed

Shi, Dejing; Zhu, Chunbo; Lu, Rengui; Mao, Shitong; Qi, Yanhua

2014-10-01

The aim of this study was to evaluate effects of intermediate frequency magnetic fields (IFMF) generated by a wireless power transmission (WPT) based on magnetic resonance from the perspective of cellular genotoxicity on cultured human lens epithelial cells (HLECs). We evaluated the effects of exposure to 90 kHz magnetic fields at 93.36 µT on cellular genotoxicity in vitro for 2 and 4 h. The magnetic flux density is approximately 3.5 times higher than the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. For assessment of genotoxicity, we studied cellular proliferation, apoptosis and DNA damage by Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, alkaline comet assay and phosphorylated histone H2AX (γH2AX) foci formation test. We did not detect any effect of a 90 kHz IFMF generated by WPT based on magnetic resonance on cell proliferation, apoptosis, comet assay, and γH2AX foci formation test. Our results indicated that exposure to 90 kHz IFMF generated by WPT based on magnetic resonance at 93.36 µT for 2 and 4 h does not cause detectable cellular genotoxicity. © 2014 Wiley Periodicals, Inc.

Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

NASA Astrophysics Data System (ADS)

Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

2011-07-01

Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs toxicity is suggested oxidative stress and lipid peroxidation playing an important role in Ag NPs elicited cell membrane disruption, DNA damage, protein damage and subsequent cell death. Our preliminary data suggest that oxidative stress might contribute to Ag NPs cytotoxicity. To reveal whether apoptosis involved in Ag NPs toxicity, further studies are underway.

ATM directs DNA damage responses and proteostasis via genetically separable pathways

PubMed Central

Lee, Ji-Hoon; Mand, Michael R.; Kao, Chung-Hsuan; Zhou, Yi; Ryu, Seung W.; Richards, Alicia L.; Coon, Joshua J.; Paull, Tanya T.

2018-01-01

The protein kinase ATM is a master regulator of the DNA damage response but also responds directly to oxidative stress. Loss of ATM causes Ataxia telangiectasia, a neurodegenerative disorder with pleiotropic symptoms that include cerebellar dysfunction, cancer, diabetes, and premature aging. Here, we genetically separated DNA damage activation of ATM from oxidative activation using separation-of-function mutations. We found that deficiency in ATM activation by Mre11-Rad50-Nbs1 and DNA double-strand breaks resulted in loss of cell viability, checkpoint activation, and DNA end resection in response to DNA damage. In contrast, loss of oxidative activation of ATM had minimal effects on DNA damage-related outcomes but blocked ATM-mediated initiation of checkpoint responses after oxidative stress and resulted in deficiencies in mitochondrial function and autophagy. In addition, expression of ATM lacking oxidative activation generates widespread protein aggregation. These results indicate a direct relationship between the mechanism of ATM activation and its effects on cellular metabolism and DNA damage responses in human cells and implicates ATM in the control of protein homeostasis. PMID:29317520

Mutational Signature Mark Cancer’s Smoking Gun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexandrov, Ludmil

A broad computational study of cancer genome sequences by Los Alamos National Laboratory with the UK’s Wellcome Trust Sanger Institute and other collaborators identifies telltale mutational signatures associated with smoking tobacco. The research demonstrates, for the first time, that smoking increases cancer risk by causing somatic mutations in tissues directly and indirectly exposed to tobacco smoke. The international study was published in the November 4 issue of Science. The analysis shows that tobacco smoking causes mutations leading to cancer by multiple distinct mechanisms, including by damaging DNA in organs and by speeding up a mutational cellular clock.

Mutational Signature Mark Cancer’s Smoking Gun

ScienceCinema

Alexandrov, Ludmil

2018-06-13

A broad computational study of cancer genome sequences by Los Alamos National Laboratory with the UK’s Wellcome Trust Sanger Institute and other collaborators identifies telltale mutational signatures associated with smoking tobacco. The research demonstrates, for the first time, that smoking increases cancer risk by causing somatic mutations in tissues directly and indirectly exposed to tobacco smoke. The international study was published in the November 4 issue of Science. The analysis shows that tobacco smoking causes mutations leading to cancer by multiple distinct mechanisms, including by damaging DNA in organs and by speeding up a mutational cellular clock.

Intense THz pulses cause H2AX phosphorylation and activate DNA damage response in human skin tissue

PubMed Central

Titova, Lyubov V.; Ayesheshim, Ayesheshim K.; Golubov, Andrey; Fogen, Dawson; Rodriguez-Juarez, Rocio; Hegmann, Frank A.; Kovalchuk, Olga

2013-01-01

Recent emergence and growing use of terahertz (THz) radiation for medical imaging and public security screening raise questions on reasonable levels of exposure and health consequences of this form of electromagnetic radiation. In particular, picosecond-duration THz pulses have shown promise for novel diagnostic imaging techniques. However, the effects of THz pulses on human cells and tissues thus far remain largely unknown. We report on the investigation of the biological effects of pulsed THz radiation on artificial human skin tissues. We observe that exposure to intense THz pulses for ten minutes leads to a significant induction of H2AX phosphorylation, indicating that THz pulse irradiation may cause DNA damage in exposed skin tissue. At the same time, we find a THz-pulse-induced increase in the levels of several proteins responsible for cell-cycle regulation and tumor suppression, suggesting that DNA damage repair mechanisms are quickly activated. Furthermore, we find that the cellular response to pulsed THz radiation is significantly different from that induced by exposure to UVA (400 nm). PMID:23577291

Intense THz pulses cause H2AX phosphorylation and activate DNA damage response in human skin tissue.

PubMed

Titova, Lyubov V; Ayesheshim, Ayesheshim K; Golubov, Andrey; Fogen, Dawson; Rodriguez-Juarez, Rocio; Hegmann, Frank A; Kovalchuk, Olga

2013-04-01

Recent emergence and growing use of terahertz (THz) radiation for medical imaging and public security screening raise questions on reasonable levels of exposure and health consequences of this form of electromagnetic radiation. In particular, picosecond-duration THz pulses have shown promise for novel diagnostic imaging techniques. However, the effects of THz pulses on human cells and tissues thus far remain largely unknown. We report on the investigation of the biological effects of pulsed THz radiation on artificial human skin tissues. We observe that exposure to intense THz pulses for ten minutes leads to a significant induction of H2AX phosphorylation, indicating that THz pulse irradiation may cause DNA damage in exposed skin tissue. At the same time, we find a THz-pulse-induced increase in the levels of several proteins responsible for cell-cycle regulation and tumor suppression, suggesting that DNA damage repair mechanisms are quickly activated. Furthermore, we find that the cellular response to pulsed THz radiation is significantly different from that induced by exposure to UVA (400 nm).

Escherichia coli cellular responses to exposure to atmospheric-pressure dielectric barrier discharge plasma-treated N-acetylcysteine solution.

PubMed

Ercan, U K; Sen, B; Brooks, A D; Joshi, S G

2018-04-06

To understand the underlying cellular mechanisms during inactivation of Escherichia coli in response to antimicrobial solution of nonthermal plasma-activated N-acetylcysteine (NAC). The recommended techniques were used to demonstrate E. coli cellular and transcriptomic changes caused associated with peroxynitrite and compared with plasma-treated NAC solution. The findings demonstrate that E. coli cells respond to plasma-treated NAC and undergo severe oxidative and nitrosative stress, and leading to stress-induced damages to different components of bacterial cells, which includes loss of membrane potential, formation of oxidized glutathione (GSSG), formation of nitrotyrosine (a known marker of nitrosative stress), DNA damage, and generated a prominent pool of peroxynitrite. Reverse-transcriptase (RT)-polymerase chain reaction analysis of reactive nitrogen species (RNS) responsive genes indicated their differential expressions. For the first time, we report that the plasma-treated NAC solution activates predominantly nitrosative stress-responsive genes in E. coli and is responsible for cell death. The reactive species generated in solutions by nonthermal plasma treatment depends on the type of solution or solvent used. The plasma-treated NAC solution rapidly inactivates E. coli, mostly involving highly RNS generated in NAC solution, and has high potential as disinfectant. © 2018 The Society for Applied Microbiology.

The suppression of radiation-induced NF-{kappa}B activity by dexamethasone correlates with increased cell death in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, Seon Young; Chung, Hee-Yong

2005-10-21

In this study, we show that dexamethasone treatment increases ionizing radiation-induced cell death by inducing the inhibitory {kappa}B{alpha} (I{kappa}B{alpha}) pathway in mice. The effect of dexamethasone on radiation-induced cell death was assessed by changes in total spleen cellularity and bone marrow colony-forming unit-granulocyte-macrophage (CFU-GM) contents after total body irradiation. While in vivo treatment of mice with dexamethasone alone (1 mg/kg/day, for 2 days) failed to elicit cell death in spleen cells, the combined treatment with dexamethasone (1 mg/kg/day, for 2 days) and {gamma}-rays (1 or 5 Gy) caused a 50-80% reduction in total cellularity in spleen and CFU-GM contents inmore » bone marrow. These results demonstrate that dexamethasone has a synergistic effect on radiation-induced cellular damages in vivo. Immunoblot analysis showed that dexamethasone treatment significantly increases I{kappa}B{alpha} expression in the spleens of irradiated mice. In addition, the dexamethasone treatment significantly reduced radiation-induced nuclear translocation of the nucleus factor-{kappa}B in the spleens of irradiated mice. These results indicate that dexamethasone treatment in vivo may increase radiation-induced cell damages by increasing I{kappa}B{alpha} expression in hematopoietic organs such as spleen and bone marrow.« less

Sod1 Loss Induces Intrinsic Superoxide Accumulation Leading to p53-Mediated Growth Arrest and Apoptosis

PubMed Central

Watanabe, Kenji; Shibuya, Shuichi; Koyama, Hirofumi; Ozawa, Yusuke; Toda, Toshihiko; Yokote, Koutaro; Shimizu, Takahiko

2013-01-01

Oxidative damages induced by a redox imbalance cause age-related changes in cells and tissues. Superoxide dismutase (SOD) enzymes play a major role in the antioxidant system and they also catalyze superoxide radicals (O2•−). Since the loss of cytoplasmic SOD (SOD1) resulted in aging-like phenotypes in several types of mouse tissue, SOD1 is essential for the maintenance of tissue homeostasis. To clarify the cellular function of SOD1, we investigated the cellular phenotypes of Sod1-deficient fibroblasts. We demonstrated that Sod1 deficiency impaired proliferation and induced apoptosis associated with O2•− accumulation in the cytoplasm and mitochondria in fibroblasts. Sod1 loss also decreased the mitochondrial membrane potential and led to DNA damage-mediated p53 activation. Antioxidant treatments effectively improved the cellular phenotypes through suppression of both intracellular O2•− accumulation and p53 activation in Sod1-deficient fibroblasts. In vivo experiments revealed that transdermal treatment with a vitamin C derivative significantly reversed the skin thinning commonly associated with the upregulated p53 action in the skin. Our findings revealed that intrinsic O2•− accumulation promoted p53-mediated growth arrest and apoptosis as well as mitochondrial disfunction in the fibroblasts. PMID:23708100

Phototoxicity to the retina: mechanisms of damage.

PubMed

Glickman, Randolph D

2002-01-01

Light damage to the retina occurs through three general mechanisms involving thermal, mechanical, or photochemical effects. The particular mechanism activated depends on the wavelength and exposure duration of the injuring light. The transitions between the various light damage mechanism may overlap to some extent. Energy confinement is a key concept in understanding or predicting the type of damage mechanism produced by a given light exposure. As light energy (either from a laser or an incoherent source) is deposited in the retina, its penetration through, and its absorption in, various tissue compartments is determined by its wavelength. Strongly absorbing tissue components will tend to "concentrate" the light energy. The effect of absorbed light energy largely depends on the rate of energy deposition, which is correlated with the exposure duration. If the rate of energy deposition is too low to produce an appreciable temperature increase in the tissue, then any resulting tissue damage necessarily occurs because of chemical (oxidative) reactions induced by absorption of energetic photons (photochemical damage). If the rate of energy deposition is faster than the rate of thermal diffusion (thermal confinement), then the temperature of the exposed tissue rises. If a critical temperature is reached (typically about 10 degrees C above basal), then thermal damage occurs. If the light energy is deposited faster than mechanical relaxation can occur (stress confinement), then a thermoelastic pressure wave is produced, and tissue is disrupted by shear forces or by cavitation-nonlinear effects. Very recent evidence suggests that ultrashort laser pulses can produce tissue damage through nonlinear and photochemical mechanisms; the latter because of two-photon excitation of cellular chromophores. In addition to tissue damage caused directly by light absorption, light toxicity can be produced by the presence of photosensitizing agents. Drugs excited to reactive states by ultraviolet (UV) or visible light produce damage by type I (free radical) and type II (oxygen dependent) mechanisms. Some commonly used drugs, such as certain antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and psychotherapeutic agents, as well as some popular herbal medicines, can produce ocular phototoxicity. Specific cellular effects and damage end points characteristic of light damage mechanisms are described.

Cellular damage in bacterial meningitis: an interplay of bacterial and host driven toxicity.

PubMed

Weber, Joerg R; Tuomanen, Elaine I

2007-03-01

Bacterial meningitis is still an important infectious disease causing death and disability. Invasive bacterial infections of the CNS generate some of the most powerful inflammatory responses known in medicine. Although the components of bacterial cell surfaces are now chemically defined in exquisite detail and the interaction with several receptor pathways has been discovered, it is only very recently that studies combining these advanced biochemical and cell biological tools have been done. Additional to the immunological response direct bacterial toxicity has been identified as an important contributor to neuronal damage. A detailed understanding of the complex interaction of bacterial toxicity and host response may generate opportunities for innovative and specific neuroprotective therapies.

Deregulation of vital mitotic kinase-phosphatase signaling in hematopoietic stem/progenitor compartment leads to cellular catastrophe in experimental aplastic anemia.

PubMed

Chatterjee, Ritam; Chattopadhyay, Sukalpa; Law, Sujata

2016-11-01

Aplastic anemia, the paradigm of bone marrow failure, is characterized by pancytopenic peripheral blood and hypoplastic bone marrow. Among various etiologies, inappropriate use of DNA alkylating drugs like cyclophosphamide and busulfan often causes the manifestation of the dreadful disease. Cell cycle impairment in marrow hematopoietic stem/progenitor compartment together with cellular apoptosis has been recognized as culpable factors behind aplastic pathophysiologies. However, the intricate molecular mechanisms remain unrevealed till date. In the present study, we have dealt with the mechanistic intervention of the disease by peripheral blood hemogram, bone marrow histopathology, cytopathology, hematopoietic kinetic study, scanning electron microscopy, DNA damage assessment and flowcytometric analysis of cellular proliferation and apoptosis in hematopoietic stem/progenitor cell (HSPC) rich marrow compartment using busulfan and cyclophosphamidemediated mouse model. To unveil the molecular mechanisms behind aplastic pathophysiology, we further investigated the role of some crucial mitotic and apoptotic regulators like Protein kinase-B (PKB), Gsk-3β, Cyclin-D1, PP2A, Cdc25c, Plk-1, Aurora kinase-A, Chk-1 regarding the hematopoietic catastrophe. Our observations revealed that the alteration of PKB-GSK-3β axis, Plk-1, and Aurora kinase-A expressions in HSPC compartment due to DNA damage response was associated with the proliferative impairment and apoptosis during aplastic anemia. The study established the correlation between the accumulation of DNA damage and alteration of the mentioned molecules in aplastic HSPCs that lead to the hematopoietic catastrophe. We anticipate that our findings will be beneficial for developing better therapeutic strategies for the dreadful disease concerned.

Dental pulp stem cells promote regeneration of damaged neuron cells on the cellular model of Alzheimer's disease.

PubMed

Wang, Feixiang; Jia, Yali; Liu, Jiajing; Zhai, Jinglei; Cao, Ning; Yue, Wen; He, Huixia; Pei, Xuetao

2017-06-01

Alzheimer's disease (AD) is an incurable neurodegenerative disease and many types of stem cells have been used in AD therapy with some favorable effects. In this study, we investigated the potential therapeutical effects of human dental pulp stem cells (hDPSCs) on AD cellular model which established by okadaic acid (OA)-induced damage to human neuroblastoma cell line, SH-SY5Y, in vitro for 24 h. After confirmed the AD cellular model, the cells were co-culture with hDPSCs by transwell co-culture system till 24 h for treatment. Then the cytomorphology of the hDPSCs-treated cells were found to restore gradually with re-elongation of retracted dendrites. Meanwhile, Cell Counting Kit-8 assay and Hoechst 33258 staining showed that hDPSCs caused significant increase in the viability and decrease in apoptosis of the model cells, respectively. Observation of DiI labeling also exhibited the prolongation dendrites in hDPSCs-treated cells which were obviously different from the retraction dendrites in AD model cells. Furthermore, specific staining of α-tubulin and F-actin demonstrated that the hDPSCs-treated cells had the morphology of restored neurons, with elongated dendrites, densely arranged microfilaments, and thickened microtubular fibrils. In addition, results from western blotting revealed that phosphorylation at Ser 396 of Tau protein was significantly suppressed by adding of hDPSCs. These results indicate that hDPSCs may promote regeneration of damaged neuron cells in vitro model of AD and may serve as a useful cell source for treatment of AD. © 2017 International Federation for Cell Biology.

Haloperidol-loaded lipid-core polymeric nanocapsules reduce DNA damage in blood and oxidative stress in liver and kidneys of rats

NASA Astrophysics Data System (ADS)

Roversi, Katiane; Benvegnú, Dalila M.; Roversi, Karine; Trevizol, Fabíola; Vey, Luciana T.; Elias, Fabiana; Fracasso, Rafael; Motta, Mariana H.; Ribeiro, Roseane F.; dos S. Hausen, Bruna; Moresco, Rafael N.; Garcia, Solange C.; da Silva, Cristiane B.; Burger, Marilise E.

2015-04-01

Haloperidol (HP) nanoencapsulation improves therapeutic efficacy, prolongs the drug action time, and reduces its motor side effects. However, in a view of HP toxicity in organs like liver and kidneys in addition to the lack of knowledge regarding the toxicity of polymeric nanocapsules, our aim was to verify the influence of HP-nanoformulation on toxicity and oxidative stress markers in the liver and kidneys of rats, also observing the damage caused in the blood. For such, 28 adult male Wistar rats were designated in four experimental groups ( n = 7) and treated with vehicle (C group), free haloperidol suspension (FH group), blank nanocapsules suspension (B-Nc group), and haloperidol-loaded lipid-core nanocapsules suspension (H-Nc group). The nanocapsules formulation presented the size of approximately 250 nm. All suspensions were administered to the animals (0.5 mg/kg/day-i.p.) for a period of 28 days. Our results showed that FH caused damage in the liver, evidenced by increased lipid peroxidation, plasma levels of aspartate aminotransferase, and alanine aminotransferase, as well as decreased cellular integrity and vitamin C levels. In kidneys, FH treatment caused damage to a lesser extent, observed by decreased activity of δ-aminolevulinate dehydratase (ALA-D) and levels of VIT C. In addition, FH treatment was also related to a higher DNA damage index in blood. On the other hand, animals treated with H-Nc and B-Nc did not show damage in liver, kidneys, and DNA. Our study indicates that the nanoencapsulation of haloperidol was able to prevent the sub-chronic toxicity commonly observed in liver, kidneys, and DNA, thus reflecting a pharmacological superiority in relation to free drug.

Enterococcus faecalis Responds to Individual Exogenous Fatty Acids Independently of Their Degree of Saturation or Chain Length

PubMed Central

2017-01-01

ABSTRACT Enterococcus faecalis is a commensal of the human gastrointestinal tract that can persist in the external environment and is a leading cause of hospital-acquired infections. Given its diverse habitats, the organism has developed numerous strategies to survive a multitude of environmental conditions. Previous studies have demonstrated that E. faecalis will incorporate fatty acids from bile and serum into its membrane, resulting in an induced tolerance to membrane-damaging agents. To discern whether all fatty acids induce membrane stress protection, we examined how E. faecalis responded to individually supplied fatty acids. E. faecalis readily incorporated fatty acids 14 to 18 carbons in length into its membrane but poorly incorporated fatty acids shorter or longer than this length. Supplementation with saturated fatty acids tended to increase generation time and lead to altered cellular morphology in most cases. Further, exogenously supplied saturated fatty acids did not induce tolerance to the membrane-damaging antibiotic daptomycin. Supplementation with unsaturated fatty acids produced variable growth effects, with some impacting generation time and morphology. Exogenously supplied unsaturated fatty acids that are normally produced by E. faecalis and those that are found in bile or serum could restore growth in the presence of a fatty acid biosynthetic inhibitor. However, only the eukaryote-derived fatty acids oleic acid and linoleic acid provided protection from daptomycin. Thus, exogenous fatty acids do not lead to a common physiological effect on E. faecalis. The organism responds uniquely to each, and only host-derived fatty acids induce membrane protection. IMPORTANCE Enterococcus faecalis is a commonly acquired hospital infectious agent with resistance to many antibiotics, including those that target its cellular membrane. We previously demonstrated that E. faecalis will incorporate fatty acids found in human fluids, like serum, into its cellular membrane, thereby altering its membrane composition. In turn, the organism is better able to survive membrane-damaging agents, including the antibiotic daptomycin. We examined fatty acids commonly found in serum and those normally produced by E. faecalis to determine which fatty acids can induce protection from membrane damage. Supplementation with individual fatty acids produced a myriad of different effects on cellular growth, morphology, and stress response. However, only host-derived unsaturated fatty acids provided stress protection. Future studies are aimed at understanding how these specific fatty acids induce protection from membrane damage. PMID:29079613

Stem cell therapy emerging as the key player in treating type 1 diabetes mellitus.

PubMed

Vanikar, Aruna V; Trivedi, Hargovind L; Thakkar, Umang G

2016-09-01

Type 1 diabetes mellitus (T1DM) is an autoimmune disease causing progressive destruction of pancreatic β cells, ultimately resulting in loss of insulin secretion producing hyperglycemia usually affecting children. Replacement of damaged β cells by cell therapy can treat it. Currently available strategies are insulin replacement and islet/pancreas transplantation. Unfortunately these offer rescue for variable duration due to development of autoantibodies. For pancreas/islet transplantation a deceased donor is required and various shortfalls of treatment include quantum, cumbersome technique, immune rejection and limited availability of donors. Stem cell therapy with assistance of cellular reprogramming and β-cell regeneration can open up new therapeutic modalities. The present review describes the history and current knowledge of T1DM, evolution of cell therapies and different cellular therapies to cure this condition. Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Mitochondrial oxidative stress in aging and healthspan

PubMed Central

2014-01-01

The free radical theory of aging proposes that reactive oxygen species (ROS)-induced accumulation of damage to cellular macromolecules is a primary driving force of aging and a major determinant of lifespan. Although this theory is one of the most popular explanations for the cause of aging, several experimental rodent models of antioxidant manipulation have failed to affect lifespan. Moreover, antioxidant supplementation clinical trials have been largely disappointing. The mitochondrial theory of aging specifies more particularly that mitochondria are both the primary sources of ROS and the primary targets of ROS damage. In addition to effects on lifespan and aging, mitochondrial ROS have been shown to play a central role in healthspan of many vital organ systems. In this article we review the evidence supporting the role of mitochondrial oxidative stress, mitochondrial damage and dysfunction in aging and healthspan, including cardiac aging, age-dependent cardiovascular diseases, skeletal muscle aging, neurodegenerative diseases, insulin resistance and diabetes as well as age-related cancers. The crosstalk of mitochondrial ROS, redox, and other cellular signaling is briefly presented. Potential therapeutic strategies to improve mitochondrial function in aging and healthspan are reviewed, with a focus on mitochondrial protective drugs, such as the mitochondrial antioxidants MitoQ, SkQ1, and the mitochondrial protective peptide SS-31. PMID:24860647

Dihydroartemisinin Exerts Its Anticancer Activity through Depleting Cellular Iron via Transferrin Receptor-1

PubMed Central

Ba, Qian; Zhou, Naiyuan; Duan, Juan; Chen, Tao; Hao, Miao; Yang, Xinying; Li, Junyang; Yin, Jun; Chu, Ruiai; Wang, Hui

2012-01-01

Artemisinin and its main active metabolite dihydroartemisinin, clinically used antimalarial agents with low host toxicity, have recently shown potent anticancer activities in a variety of human cancer models. Although iron mediated oxidative damage is involved, the mechanisms underlying these activities remain unclear. In the current study, we found that dihydroartemisinin caused cellular iron depletion in time- and concentration-dependent manners. It decreased iron uptake and disturbed iron homeostasis in cancer cells, which were independent of oxidative damage. Moreover, dihydroartemisinin reduced the level of transferrin receptor-1 associated with cell membrane. The regulation of dihydroartemisinin to transferrin receptor-1 could be reversed by nystatin, a cholesterol-sequestering agent but not the inhibitor of clathrin-dependent endocytosis. Dihydroartemisinin also induced transferrin receptor-1 palmitoylation and colocalization with caveolin-1, suggesting a lipid rafts mediated internalization pathway was involved in the process. Also, nystatin reversed the influences of dihydroartemisinin on cell cycle and apoptosis related genes and the siRNA induced downregulation of transferrin receptor-1 decreased the sensitivity to dihydroartemisinin efficiently in the cells. These results indicate that dihydroartemisinin can counteract cancer through regulating cell-surface transferrin receptor-1 in a non-classical endocytic pathway, which may be a new action mechanism of DHA independently of oxidative damage. PMID:22900042

An insert-based enzymatic cell culture system to rapidly and reversibly induce hypoxia: investigations of hypoxia-induced cell damage, protein expression and phosphorylation in neuronal IMR-32 cells

PubMed Central

Huang, Ying; Zitta, Karina; Bein, Berthold; Steinfath, Markus; Albrecht, Martin

2013-01-01

SUMMARY Ischemia-reperfusion injury and tissue hypoxia are of high clinical relevance because they are associated with various pathophysiological conditions such as myocardial infarction and stroke. Nevertheless, the underlying mechanisms causing cell damage are still not fully understood, which is at least partially due to the lack of cell culture systems for the induction of rapid and transient hypoxic conditions. The aim of the study was to establish a model that is suitable for the investigation of cellular and molecular effects associated with transient and long-term hypoxia and to gain insights into hypoxia-mediated mechanisms employing a neuronal culture system. A semipermeable membrane insert system in combination with the hypoxia-inducing enzymes glucose oxidase and catalase was employed to rapidly and reversibly generate hypoxic conditions in the culture medium. Hydrogen peroxide assays, glucose measurements and western blotting were performed to validate the system and to evaluate the effects of the generated hypoxia on neuronal IMR-32 cells. Using the insert-based two-enzyme model, hypoxic conditions were rapidly induced in the culture medium. Glucose concentrations gradually decreased, whereas levels of hydrogen peroxide were not altered. Moreover, a rapid and reversible (onoff) generation of hypoxia could be performed by the addition and subsequent removal of the enzyme-containing inserts. Employing neuronal IMR-32 cells, we showed that 3 hours of hypoxia led to morphological signs of cellular damage and significantly increased levels of lactate dehydrogenase (a biochemical marker of cell damage). Hypoxic conditions also increased the amounts of cellular procaspase-3 and catalase as well as phosphorylation of the pro-survival kinase Akt, but not Erk1/2 or STAT5. In summary, we present a novel framework for investigating hypoxia-mediated mechanisms at the cellular level. We claim that the model, the first of its kind, enables researchers to rapidly and reversibly induce hypoxic conditions in vitro without unwanted interference of the hypoxia-inducing agent on the cultured cells. The system could help to further unravel hypoxia-associated mechanisms that are clinically relevant in various tissues and organs. PMID:24046359

Creating Age Asymmetry: Consequences of Inheriting Damaged Goods in Mammalian Cells.

PubMed

Moore, Darcie L; Jessberger, Sebastian

2017-01-01

Accumulating evidence suggests that mammalian cells asymmetrically segregate cellular components ranging from genomic DNA to organelles and damaged proteins during cell division. Asymmetric inheritance upon mammalian cell division may be specifically important to ensure cellular fitness and propagate cellular potency to individual progeny, for example in the context of somatic stem cell division. We review here recent advances in the field and discuss potential effects and underlying mechanisms that mediate asymmetric segregation of cellular components during mammalian cell division. Copyright © 2016 Elsevier Ltd. All rights reserved.

Glutathione-mediated detoxification of halobenzoquinone drinking water disinfection byproducts in T24 cells.

PubMed

Li, Jinhua; Wang, Wei; Zhang, Hongquan; Le, X Chris; Li, Xing-Fang

2014-10-01

Halobenzoquinones (HBQs) are a new class of drinking water disinfection byproducts (DBPs) and are capable of producing reactive oxygen species and causing oxidative damage to proteins and DNA in T24 human bladder carcinoma cells. However, the exact mechanism of the cytotoxicity of HBQs is unknown. Here, we investigated the role of glutathione (GSH) and GSH-related enzymes including glutathione S-transferase (GST) and glutathione peroxidase (GPx) in defense against HBQ-induced cytotoxicity in T24 cells. The HBQs are 2,6-dichloro-1,4-benzoquinone (DCBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), 2,3,6-trichloro-1,4-benzoquinone (TriCBQ), and 2,6-dibromobenzoquinone (DBBQ). We found that depletion of cellular GSH could sensitize cells to HBQs and extracellular GSH supplementation could attenuate HBQ-induced cytotoxicity. HBQs caused significant cellular GSH depletion and increased cellular GST activities in a concentration-dependent manner. Our mass spectrometry study confirms that HBQs can conjugate with GSH, explaining in part the mechanism of GSH depletion by HBQs. The effects of HBQs on GPx activity are compound dependent; DCMBQ and DBBQ decrease cellular GPx activities, whereas DCBQ and TriCBQ have no significant effects. Pearson correlation analysis shows that the cellular GSH level is inversely correlated with ROS production and cellular GST activity in HBQ-treated cells. These results support a GSH and GSH-related enzyme-mediated detoxification mechanism of HBQs in T24 cells. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Inactivation dynamics of 222 nm krypton-chlorine excilamp irradiation on Gram-positive and Gram-negative foodborne pathogenic bacteria.

PubMed

Kang, Jun-Won; Kim, Sang-Soon; Kang, Dong-Hyun

2018-07-01

The object of this study was to elucidate the bactericidal mechanism of a 222 nm Krypton Chlorine (KrCl) excilamp compared with that of a 254 nm Low Pressure mercury (LP Hg) lamp. The KrCl excilamp had higher bactericidal capacity against Gram-positive pathogenic bacteria (Staphylococcus aureus and L. monocytogenes) and Gram-negative pathogenic bacteria (S. Typhimurium and E. coli O157:H7) than did the LP Hg lamp when cell suspensions in PBS were irradiated with each type of UV lamp. It was found out that the KrCl excilamp induced cell membrane damage as a form of depolarization. From the study of respiratory chain dehydrogenase activity and the lipid peroxidation assay, it was revealed that cell membrane damage was attributed to inactivation of enzymes related to generation of membrane potential and occurrence of lipid peroxidation. Direct absorption of UV radiation which led to photoreaction through formation of an excited state was one of the causes inducing cell damage. Additionally, generation of ROS and thus occurrence of secondary damage can be another cause. The LP Hg lamp only induced damage to DNA but not to other components such as lipids or proteins. This difference was derived from differences of UV radiation absorption by cellular materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of energetic-particle-irradiation induced biological effect on Rhizopus oryzae through synchrotron-FTIR micro-spectroscopy

NASA Astrophysics Data System (ADS)

Liu, Jinghua; Qi, Zeming; Huang, Qing; Wei, Xiaoli; Ke, Zhigang; Fang, Yusheng; Tian, Yangchao; Yu, Zengliang

2013-01-01

Energetic particles exist ubiquitously and cause varied biological effects such as DNA strand breaks, lipid peroxidation, protein modification, cell apoptosis or death. An emerging biotechnology based on ion-beam technique has been developed to serve as an effective tool for mutation breeding of crops and microbes. In order to improve the effectiveness of ion-beam biotechnology for mutation breeding, it is indispensible to gain a better understanding of the mechanism of the interactions between the energetic ions and biological systems which is still elusive. A new trend is to conduct more comprehensive research which is based on micro-scaled observation of the changes of the cellular structures and compositions under the interactions. For this purpose, advanced synchrotron FTIR (s-FTIR) microscopy was employed to monitor the cellular changes of single fungal hyphae under irradiation of α-particles from 241Am. Intracellular contents of ROS, MDA, GSSG/GSH and activities of CAT and SOD were measured via biochemical assay. Ion-irradiation on Rhizopus oryzae causes localized vacuolation, autolysis of cell wall and membrane, lipid peroxidation, DNA damage and conformational changes of proteins, which have been clearly revealed by the s-FTIR microspectroscopy. The different changes of cell viability, SOD and CAT activities can be explained by the ROS-involved chemical reactions. Evidently, the elevated level of ROS in hyphal cells upon irradiation plays the key role in the caused biological effect. This study demonstrates that s-FTIR microspectroscopy is an effective tool to study the damage of fungal hyphae caused by ionizing radiation and it facilitates the exploit of the mechanism for the interactions between the energetic ions and biological systems.

Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli.

PubMed

Moore, Jessica M; Correa, Raul; Rosenberg, Susan M; Hastings, P J

2017-07-01

Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS oxidation of DNA potentially regulated by ROS regulators.

Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli

PubMed Central

Moore, Jessica M.; Correa, Raul; Rosenberg, Susan M.

2017-01-01

Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS oxidation of DNA potentially regulated by ROS regulators. PMID:28727736

Atorvastatin Downregulates In Vitro Methyl Methanesulfonate and Cyclophosphamide Alkylation-Mediated Cellular and DNA Injuries

PubMed Central

Christoni, Larissa S. A.; Justo, Graça; Soeiro, Maria N. C.

2018-01-01

Statins are 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, and this class of drugs has been studied as protective agents against DNA damages. Alkylating agents (AAs) are able to induce alkylation in macromolecules, causing DNA damage, as DNA methylation. Our objective was to evaluate atorvastatin (AVA) antimutagenic, cytoprotective, and antigenotoxic potentials against DNA lesions caused by AA. AVA chemopreventive ability was evaluated using antimutagenicity assays (Salmonella/microsome assay), cytotoxicity, cell cycle, and genotoxicity assays in HepG2 cells. The cells were cotreated with AVA and the AA methyl methanesulfonate (MMS) or cyclophosphamide (CPA). Our datum showed that AVA reduces the alkylation-mediated DNA damage in different in vitro experimental models. Cytoprotection of AVA at low doses (0.1–1.0 μM) was observed after 24 h of cotreatment with MMS or CPA at their LC50, causing an increase in HepG2 survival rates. After all, AVA at 10 μM and 25 μM had decreased effect in micronucleus formation in HepG2 cells and restored cell cycle alterations induced by MMS and CPA. This study supports the hypothesis that statins can be chemopreventive agents, acting as antimutagenic, antigenotoxic, and cytoprotective components, specifically against alkylating agents of DNA. PMID:29849914

Interplay of space radiation and microgravity in DNA damage and DNA damage response.

PubMed

Moreno-Villanueva, María; Wong, Michael; Lu, Tao; Zhang, Ye; Wu, Honglu

2017-01-01

In space, multiple unique environmental factors, particularly microgravity and space radiation, pose constant threat to the DNA integrity of living organisms. Specifically, space radiation can cause damage to DNA directly, through the interaction of charged particles with the DNA molecules themselves, or indirectly through the production of free radicals. Although organisms have evolved strategies on Earth to confront such damage, space environmental conditions, especially microgravity, can impact DNA repair resulting in accumulation of severe DNA lesions. Ultimately these lesions, namely double strand breaks, chromosome aberrations, micronucleus formation, or mutations, can increase the risk for adverse health effects, such as cancer. How spaceflight factors affect DNA damage and the DNA damage response has been investigated since the early days of the human space program. Over the years, these experiments have been conducted either in space or using ground-based analogs. This review summarizes the evidence for DNA damage induction by space radiation and/or microgravity as well as spaceflight-related impacts on the DNA damage response. The review also discusses the conflicting results from studies aimed at addressing the question of potential synergies between microgravity and radiation with regard to DNA damage and cellular repair processes. We conclude that further experiments need to be performed in the true space environment in order to address this critical question.

Mitochondria damage checkpoint in apoptosis and genome stability.

PubMed

Singh, Keshav K

2004-11-01

Mitochondria perform multiple cellular functions including energy production, cell proliferation and apoptosis. Studies described in this paper suggest a role for mitochondria in maintaining genomic stability. Genomic stability appears to be dependent on mitochondrial functions involved in maintenance of proper intracellular redox status, ATP-dependent transcription, DNA replication, DNA repair and DNA recombination. To further elucidate the role of mitochondria in genomic stability, I propose a mitochondria damage checkpoint (mitocheckpoint) that monitors and responds to damaged mitochondria. Mitocheckpoint can coordinate and maintain proper balance between apoptotic and anti-apoptotic signals. When mitochondria are damaged, mitocheckpoint can be activated to help cells repair damaged mitochondria, to restore normal mitochondrial function and avoid production of mitochondria-defective cells. If mitochondria are severely damaged, mitocheckpoint may not be able to repair the damage and protect cells. Such an event triggers apoptosis. If damage to mitochondria is continuous or persistent such as damage to mitochondrial DNA resulting in mutations, mitocheckpoint may fail which can lead to genomic instability and increased cell survival in yeast. In human it can cause cancer. In support of this proposal we provide evidence that mitochondrial genetic defects in both yeast and mammalian systems lead to impaired DNA repair, increased genomic instability and increased cell survival. This study reveals molecular genetic mechanisms underlying a role for mitochondria in carcinogenesis in humans.

Oxidative stress and pathology in muscular dystrophies: focus on protein thiol oxidation and dysferlinopathies.

PubMed

Terrill, Jessica R; Radley-Crabb, Hannah G; Iwasaki, Tomohito; Lemckert, Frances A; Arthur, Peter G; Grounds, Miranda D

2013-09-01

The muscular dystrophies comprise more than 30 clinical disorders that are characterized by progressive skeletal muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism for pathogenesis generally remains unknown. It is considered that disturbed levels of reactive oxygen species (ROS) contribute to the pathology of many muscular dystrophies. Reactive oxygen species and oxidative stress may cause cellular damage by directly and irreversibly damaging macromolecules such as proteins, membrane lipids and DNA; another major cellular consequence of reactive oxygen species is the reversible modification of protein thiol side chains that may affect many aspects of molecular function. Irreversible oxidative damage of protein and lipids has been widely studied in Duchenne muscular dystrophy, and we have recently identified increased protein thiol oxidation in dystrophic muscles of the mdx mouse model for Duchenne muscular dystrophy. This review evaluates the role of elevated oxidative stress in Duchenne muscular dystrophy and other forms of muscular dystrophies, and presents new data that show significantly increased protein thiol oxidation and high levels of lipofuscin (a measure of cumulative oxidative damage) in dysferlin-deficient muscles of A/J mice at various ages. The significance of this elevated oxidative stress and high levels of reversible thiol oxidation, but minimal myofibre necrosis, is discussed in the context of the disease mechanism for dysferlinopathies, and compared with the situation for dystrophin-deficient mdx mice. © 2013 The Authors Journal compilation © 2013 FEBS.

Phosphate toxicity: new insights into an old problem

PubMed Central

RAZZAQUE, M. Shawkat

2011-01-01

Phosphorus is an essential nutrient required for critical biological reactions that maintain the normal homoeostatic control of the cell. This element is an important component of different cellular structures, including nucleic acids and cell membranes. Adequate phosphorus balance is vital for maintaining basic cellular functions, ranging from energy metabolism to cell signalling. In addition, many intracellular pathways utilize phosphate ions for important cellular reactions; therefore, homoeostatic control of phosphate is one of the most delicate biological regulations. Impaired phosphorus balance can affect the functionality of almost every human system, including musculoskeletal and cardiovascular systems, ultimately leading to an increase in morbidity and mortality of the affected patients. Human and experimental studies have found that delicate balance among circulating factors, like vitamin D, PTH (parathyroid hormone) and FGF23 (fibroblast growth factor 23), are essential for regulation of physiological phosphate balance. Dysregulation of these factors, either alone or in combination, can induce phosphorus imbalance. Recent studies have shown that suppression of the FGF23–klotho system can lead to hyperphosphataemia with extensive tissue damage caused by phosphate toxicity. The cause and consequences of phosphate toxicity will be briefly summarized in the present review. PMID:20958267

Phosphate toxicity: new insights into an old problem.

PubMed

Razzaque, M Shawkat

2011-02-01

Phosphorus is an essential nutrient required for critical biological reactions that maintain the normal homoeostatic control of the cell. This element is an important component of different cellular structures, including nucleic acids and cell membranes. Adequate phosphorus balance is vital for maintaining basic cellular functions, ranging from energy metabolism to cell signalling. In addition, many intracellular pathways utilize phosphate ions for important cellular reactions; therefore, homoeostatic control of phosphate is one of the most delicate biological regulations. Impaired phosphorus balance can affect the functionality of almost every human system, including musculoskeletal and cardiovascular systems, ultimately leading to an increase in morbidity and mortality of the affected patients. Human and experimental studies have found that delicate balance among circulating factors, like vitamin D, PTH (parathyroid hormone) and FGF23 (fibroblast growth factor 23), are essential for regulation of physiological phosphate balance. Dysregulation of these factors, either alone or in combination, can induce phosphorus imbalance. Recent studies have shown that suppression of the FGF23-klotho system can lead to hyperphosphataemia with extensive tissue damage caused by phosphate toxicity. The cause and consequences of phosphate toxicity will be briefly summarized in the present review.

Cellular and Molecular Mechanisms of Alveolar Destruction in Emphysema

PubMed Central

Tuder, Rubin M.; Yoshida, Toshinori; Arap, Wadih; Pasqualini, Renata; Petrache, Irina

2006-01-01

Emphysema consists of a unique pattern of alveolar destruction, resulting in marked airspace enlargement with reduction of alveolar capillary exchange area. Classical concepts of the pathogenesis of emphysema have relied on the paradigm set by the inflammation and protease/antiprotease imbalance. We propose herein that cigarette smoke constitutes an environmental hazard that causes alveolar destruction by the interaction of apoptosis, oxidative stress, and protease/antiprotease imbalance. We draw a parallel between organismal aging, organ structural maintenance, and the damage resulting from chronic cigarette smoke inhalation. The stochastic interaction between environmental hazards and the effort of an organism or a particular organ to fend off these hazards results in the accumulation of cellular damage and features characteristic of aging. Inflammation follows as the result of the multiplication of injuries. We highlight the importance of understanding the biology of the interaction of alveolar cells in homeostasis and in alveolar destruction, and the potential role of novel processes related to senescence and stress response. An evolutionary perspective of emphysema that incorporates mechanisms related to aging may lead to important advances in the understanding and therapeutic targeting of chronic obstructive pulmonary disease. PMID:16921129

Adverse Health Effects of Thirdhand Smoke: From Cell to Animal Models.

PubMed

Hang, Bo; Wang, Pin; Zhao, Yue; Sarker, Altaf; Chenna, Ahmed; Xia, Yankai; Snijders, Antoine M; Mao, Jian-Hua

2017-04-28

The newly identified smoke hazard, thirdhand smoke (THS), has gained public attention in recent years but its health impact and biological effects are largely unknown. THS may be defined by "the four Rs": tobacco chemicals that remain, react, re-emit, and/or are resuspended long after active smoking has ceased. This review summarizes recent research progress in the effects of THS on genotoxicity, metabolism and early life development using cellular and animal models. We first reported that THS generated in laboratory systems caused significant DNA damage in human cell lines. Our finding that THS significantly induces oxidative base lesions has been confirmed in skin wounds of mice models exposed to THS. THS also induced metabolomic changes in human reproductive cell lines. Furthermore, we demonstrated that early exposure to THS not only negatively impacts body weight in both male and female mice, but also induces persistent changes to immunological parameters in peripheral blood in these mice. These results indicate that THS is genotoxic at realistic experimental doses and that there may be a window of susceptibility for some forms of cellular damage induced by THS.

[Stress-induced cellular adaptive mutagenesis].

PubMed

Zhu, Linjiang; Li, Qi

2014-04-01

The adaptive mutations exist widely in the evolution of cells, such as antibiotic resistance mutations of pathogenic bacteria, adaptive evolution of industrial strains, and cancerization of human somatic cells. However, how these adaptive mutations are generated is still controversial. Based on the mutational analysis models under the nonlethal selection conditions, stress-induced cellular adaptive mutagenesis is proposed as a new evolutionary viewpoint. The hypothetic pathway of stress-induced mutagenesis involves several intracellular physiological responses, including DNA damages caused by accumulation of intracellular toxic chemicals, limitation of DNA MMR (mismatch repair) activity, upregulation of general stress response and activation of SOS response. These responses directly affect the accuracy of DNA replication from a high-fidelity manner to an error-prone one. The state changes of cell physiology significantly increase intracellular mutation rate and recombination activity. In addition, gene transcription under stress condition increases the instability of genome in response to DNA damage, resulting in transcription-associated DNA mutagenesis. In this review, we summarize these two molecular mechanisms of stress-induced mutagenesis and transcription-associated DNA mutagenesis to help better understand the mechanisms of adaptive mutagenesis.

Mequindox induced cellular DNA damage via generation of reactive oxygen species.

PubMed

Liu, Jing; Ouyang, Man; Jiang, Jun; Mu, Peiqiang; Wu, Jun; Yang, Qi; Zhang, Caihui; Xu, Weiying; Wang, Lijuan; Huen, Michael S Y; Deng, Yiqun

2012-01-24

Mequindox, a quinoxaline-N-dioxide derivative that possesses antibacterial properties, has been widely used as a feed additive in the stockbreeding industry in China. While recent pharmacological studies have uncovered potential hazardous effects of mequindox, exactly how mequindox induces pathological changes and the cellular responses associated with its consumption remain largely unexplored. In this study, we investigated the cellular responses associated with mequindox treatment. We report here that mequindox inhibits cell proliferation by arresting cells at the G2/M phase of the cell cycle. Interestingly, this mequindox-associated deleterious effect on cell proliferation was observed in human, pig as well as chicken cells, suggesting that mequindox acts on evolutionarily conserved target(s). To further understand the mequindox-host interaction and the mechanism underlying mequindox-induced cell cycle arrest, we measured the cellular content of DNA damage, which is known to perturb cell proliferation and compromise cell survival. Accordingly, using γ-H2AX as a surrogate marker for DNA damage, we found that mequindox treatment induced cellular DNA damage, which paralleled the chemical-induced elevation of reactive oxygen species (ROS) levels. Importantly, expression of the antioxidant enzyme catalase partially alleviated these mequindox-associated effects. Taken together, our results suggest that mequindox cytotoxicity is attributable, in part, to its role as a potent inducer of DNA damage via ROS. © 2011 Elsevier B.V. All rights reserved.

Selective antitumor activity of roscovitine in head and neck cancer

PubMed Central

Biktasova, Asel; Bellinger, Gary; Yarbrough, Wendell G.; Issaeva, Natalia

2016-01-01

Radiation and chemotherapy that are commonly used to treat human cancers damage cellular DNA. DNA damage appears to be more toxic to cancer cells than normal cells, most likely due to deregulated checkpoint activation and/or deficiency in DNA repair pathways that are characteristics of many tumors. However, unwanted side effects arise as a result of DNA damage to normal cells during the treatment. Here, we show that roscovitine, a cyclin-dependent kinase (CDK) inhibitor that inhibits CDK-1, CDK-2, CDK-5, CDK-7, and CDK-9 due to competitive binding to the ATP site on the kinases, causes significant DNA damage followed by p53-dependent cell death in human papilloma virus (HPV)-positive, but not in HPV-negative, head and neck cancer cells. Since HPV positivity was a molecular marker for increased sensitivity of cells to roscovitine, we reasoned that systemic roscovitine administration would not be toxic to healthy HPV-negative tissue. Indeed, low roscovitine doses significantly inhibited the growth of HPV-associated xenografted tumors in mice without causing any detectable side effects. Given that inhibition of CDKs has been shown to inhibit replication of several viruses, we suggest that roscovitine treatment may represent a selective and safe targeted therapeutic option against HPV-positive head and neck cancer. PMID:27233076

Role of oxidative stress in diabetic retinopathy and the beneficial effects of flavonoids.

PubMed

Ola, Mohammad Shamsul; Al-Dosari, Dalia; Alhomida, Abdullah S

2018-05-15

Diabetic retinopathy (DR) is one of the leading causes of decreased vision and blindness in developed countries. Diabetes-induced metabolic disorder is believed to increase oxidative stress in the retina. This results in deleterious changes through dysregulation of cellular physiology that damages both neuronal and vascular cells. Here in this review, we first highlight the evidence of potential metabolic sources and pathways which increase oxidative stress that contributes to retinal pathology in diabetes. As oxidative stress is a central factor in the pathophysiology of DR, antioxidants therapy would be beneficial towards preventing the retinal damage. A number of experimental studies by us and others showed that dietary flavonoids cause reduction in increased oxidative stress and other beneficial effects in diabetic retina. We then discuss the potential beneficial effects of the six major flavonoid families, such as flavonones, flavanols, flavonols, isoflavones, flavones and anthocyanins, which have been studied to improve retinal damage. Flanonoids, being known antioxidants, may ameliorate the retinal degenerative factors including apoptosis, inflammation and neurodegeneration in the diabetic retina. Therefore, intake of potential dietary flavonoids would limit oxidative stress and thereby prevent the retinal damage, and subsequently the development of DR. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Protective effects of TES trioleate, an inhibitor of phospholipase A2, on reactive oxygen species and UVA-induced cell damage.

PubMed

Park, Soo Nam; Kim, Moon Jin; Ha, Ji Hoon; Lee, Nan Hee; Park, Jino; Lee, Jiwon; Kim, Dukha; Yoon, Chulsoo

2016-11-01

2-[Tris(oleoyloxymethyl)methylamino]-1-ethane sulfonic acid (TES trioleate) is an inhibitor of phospholipase A 2 (PLA2), which hydrolyzes cell membrane phospholipids to produce arachidonic acid (AA) and lysophospholipids (LysoPLs). Here, we investigated the protective effects of TES trioleate on cell damage caused by ultraviolet A (UVA) light and reactive oxygen species (ROS). Pre-incubation with 250-1000μM TES trioleate resulted in concentration-dependent protection from UVA-induced damage in HaCaT cells. Additionally, 25-1000μM TES trioleate provided protection against H 2 O 2 in a concentration-dependent manner. In human erythrocytes treated with 1 O 2 , 10-100μM TES trioleate showed concentration-dependent protective effects, similar to but stronger than the controls, 4-BPB and lipophilic antioxidant (+)-α-tocopherol at 100μM. TES trioleate did not have detectable radical scavenging activity. Moreover, compared with (+)-α-tocopherol and rutin, TES trioleate showed low ROS scavenging activity. Thus, although TES trioleate showed cell protective effects against UVA, H 2 O 2 , and 1 O 2 -induced damages, these effects were not caused by the scavenging ability of the radical or ROS. Finally, pretreatment of HaCaT cells and human erythrocytes with l-α-lysophosphatidylcholine produced by PLA2 promoted increased cell damage at low concentrations. Thus, the protective effects of TES trioleate on cellular damage by UVA and ROS may be associated with inhibition of PLA2-dependent cell damage rather than ROS scavenging. Copyright © 2016. Published by Elsevier B.V.

Sensing of dangerous DNA.

PubMed

Gasser, Stephan; Zhang, Wendy Y L; Tan, Nikki Yi Jie; Tripathi, Shubhita; Suter, Manuel A; Chew, Zhi Huan; Khatoo, Muznah; Ngeow, Joanne; Cheung, Florence S G

2017-07-01

The presence of damaged and microbial DNA can pose a threat to the survival of organisms. Cells express various sensors that recognize specific aspects of such potentially dangerous DNA. Recognition of damaged or microbial DNA by sensors induces cellular processes that are important for DNA repair and inflammation. Here, we review recent evidence that the cellular response to DNA damage and microbial DNA are tightly intertwined. We also discuss insights into the parameters that enable DNA sensors to distinguish damaged and microbial DNA from DNA present in healthy cells. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Influence of Echinococcus multilocularis infection on reproduction and cellular immune response of mice.

PubMed

Antolová, D; Reiterová, K

2010-05-01

The influence of secondary Echinococcus multilocularis infection on reproduction and cellular immune response of mice was studied in BALB/c mice infected with 2000 E. multilocularis protoscoleces. Of the total infected mothers, 11.7% did not give birth and 10% of uninfected ones did not deliver. Both, healthy and infected mothers, produced on average 6-7 offspring per litter. The changes in production of seral IFN-gamma, TNF and IL-10 did not significantly influence the course of gravidity. On the other hand, more intensive metacestode growth was observed after the delivery. This study confirmed the ability of host organism to adapt to severe damage caused by E. multilocularis, not only in normal conditions, but also during pregnancy.

Photochemically induced focal cochlear lesions in the guinea pig: II. A transmission electron microscope study.

PubMed

Miyashita, H; Iwasaki, S; Hoshino, T

1998-05-15

Photochemically induced focal lesions in guinea pig cochleas were studied by light microscopy and transmission electron microscopy. The lesions were induced in the second cochlear turns of 35 adult guinea pigs by illumination for 10 minutes with a focused green light immediately after a rose bengal solution was injected into the jugular vein. The cochlear lateral wall and organ of Corti were examined 5, 10, 20, 30, and 90 minutes, 12 and 24 hours, and 3, 7, and 30 days after the procedure. Aggregations of platelets and red blood cells were found in strial capillaries at 5 minutes after illumination. After 30 minutes, marginal cell surfaces protruded into the endolymphatic space; surface membranes were ruptured and the cytoplasm was expelled into the space. In outer hair cells, disruption of the cellular membrane was found near the cuticular plate 12 hours after the procedure. All cellular elements of the lateral wall and organ of Corti were markedly degenerated in the 30-day specimens. Histological changes found in the stria vascularis were consistent with cell damage caused by active oxygen species. It is likely that the stria vascularis is more sensitive to the photochemical reaction than other parts of the cochlea. Cell damage in other parts of the cochlea seemed to have been caused by local microvascular ischemia in addition to the action of active oxygen species induced by the photochemical reaction.

Microcavitation as a Neuronal Damage Mechanism in Blast Traumatic Brain Injury

NASA Astrophysics Data System (ADS)

Franck, Christian; Estrada, Jonathan

2015-11-01

Blast traumatic brain injury (bTBI) is a leading cause of injury in the armed forces. Diffuse axonal injury, the hallmark feature of blunt TBI, has been investigated in direct mechanical loading conditions. However, recent evidence suggests inertial cavitation as a possible bTBI mechanism, particularly in the case of exposure to blasts. Cavitation damage to free surfaces has been well-studied, but bubble interactions within confined 3D environments, in particular their stress and strain signatures are not well understood. The structural damage due to cavitation in living tissues - particularly at the cellular level - are incompletely understood, in part due to the rapid bubble formation and deformation strain rates of up to ~ 105-106 s-1. This project aims to characterize material damage in 2D and 3D cell culture environments by utilizing a novel high-speed red-blue diffraction assisted image correlation method at speeds of up to 106 frames per second. We gratefully acknowledge funding from the Office of Naval Research (POC: Dr. Tim Bentley).

Marine molluscs in environmental monitoring. I. Cellular and molecular responses

NASA Astrophysics Data System (ADS)

Bresler, Vladimir; Abelson, Avigdor; Fishelson, Lev; Feldstein, Tamar; Rosenfeld, Michael; Mokady, Ofer

2003-10-01

The study reported here is part of an ongoing effort to establish sensitive and reliable biomonitoring markers for probing the coastal marine environment. Here, we report comparative measurements of a range of histological, cellular and sub-cellular parameters in molluscs sampled in polluted and reference sites along the Mediterranean coast of Israel and in the northern tip of the Gulf of Aqaba, Red Sea. Available species enabled an examination of conditions in two environmental 'compartments': benthic (Donax trunculus) and intertidal (Brachidontes pharaonis, Patella caerulea) in the Mediterranean; pelagic (Pteria aegyptia) and intertidal (Cellana rota) in the Red Sea. The methodology used provides rapid results by combining specialized fluorescent probes and contact microscopy, by which all parameters are measured in unprocessed animal tissue. The research focused on three interconnected levels. First, antixenobiotic defence mechanisms aimed at keeping hazardous agents outside the cell. Paracellular permeability was 70-100% higher in polluted sites, and membrane pumps (MXRtr and SATOA) activity was up to 65% higher in polluted compared to reference sites. Second, intracellular defence mechanisms that act to minimize potential damage by agents having penetrated the first line of defence. Metallothionein expression and EROD activity were 160-520% higher in polluted sites, and lysosomal functional activity (as measured by neutral red accumulation) was 25-50% lower. Third, damage caused by agents not sufficiently eliminated by the above mechanisms (e.g. single-stranded DNA breaks, chromosome damage and other pathological alterations). At this level, the most striking differences were observed in the rate of micronuclei formation and DNA breaks (up to 150% and 400% higher in polluted sites, respectively). The different mollusc species used feature very similar trends between polluted and reference sites in all measured parameters. Concentrating on relatively basic levels of biological organization—the molecular and cellular level—the parameters measured may have the capacity not only for biomonitoring environmental quality, but also for early warning.

Effects of methyl and inorganic mercury exposure on genome homeostasis and mitochondrial function in Caenorhabditis elegans.

PubMed

Wyatt, Lauren H; Luz, Anthony L; Cao, Xiou; Maurer, Laura L; Blawas, Ashley M; Aballay, Alejandro; Pan, William K Y; Meyer, Joel N

2017-04-01

Mercury toxicity mechanisms have the potential to induce DNA damage and disrupt cellular processes, like mitochondrial function. Proper mitochondrial function is important for cellular bioenergetics and immune signaling and function. Reported impacts of mercury on the nuclear genome (nDNA) are conflicting and inconclusive, and mitochondrial DNA (mtDNA) impacts are relatively unknown. In this study, we assessed genotoxic (mtDNA and nDNA), metabolic, and innate immune impacts of inorganic and organic mercury exposure in Caenorhabditis elegans. Genotoxic outcomes measured included DNA damage, DNA damage repair (nucleotide excision repair, NER; base excision repair, BER), and genomic copy number following MeHg and HgCl 2 exposure alone and in combination with known DNA damage-inducing agents ultraviolet C radiation (UVC) and hydrogen peroxide (H 2 O 2 ), which cause bulky DNA lesions and oxidative DNA damage, respectively. Following exposure to both MeHg and HgCl 2 , low-level DNA damage (∼0.25 lesions/10kb mtDNA and nDNA) was observed. Unexpectedly, a higher MeHg concentration reduced damage in both genomes compared to controls. However, this observation was likely the result of developmental delay. In co-exposure treatments, both mercury compounds increased initial DNA damage (mtDNA and nDNA) in combination with H 2 O 2 exposure, but had no impact in combination with UVC exposure. Mercury exposure both increased and decreased DNA damage removal via BER. DNA repair after H 2 O 2 exposure in mercury-exposed nematodes resulted in damage levels lower than measured in controls. Impacts to NER were not detected. mtDNA copy number was significantly decreased in the MeHg-UVC and MeHg-H 2 O 2 co-exposure treatments. Mercury exposure had metabolic impacts (steady-state ATP levels) that differed between the compounds; HgCl 2 exposure decreased these levels, while MeHg slightly increased levels or had no impact. Both mercury species reduced mRNA levels for immune signaling-related genes, but had mild or no effects on survival on pathogenic bacteria. Overall, mercury exposure disrupted mitochondrial endpoints in a mercury-compound dependent fashion. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of methyl and inorganic mercury exposure on genome homeostasis and mitochondrial function in Caenorhabditis elegans

PubMed Central

Wyatt, Lauren H.; Luz, Anthony L.; Cao, Xiou; Maurer, Laura L.; Blawas, Ashley M.; Aballay, Alejandro; Pan, William K.; Meyer, Joel N.

2017-01-01

Mercury toxicity mechanisms have the potential to induce DNA damage and disrupt cellular processes, like mitochondrial function. Proper mitochondrial function is important for cellular bioenergetics and immune signaling and function. Impacts of mercury on the nuclear genome (nDNA) are conflicting and inconclusive, and mitochondrial DNA (mtDNA) impacts are relatively unknown. In this study, we assessed genotoxic (mtDNA and nDNA), metabolic, and innate immune impacts of inorganic and organic mercury exposure in Caenorhabditis elegans. Genotoxic outcomes measured included DNA damage, DNA damage repair (nucleotide excision repair, NER; base excision repair, BER), and genomic copy number following MeHg and HgCl2 exposure alone and in combination with known DNA damage-inducing agents ultraviolet C radiation (UVC) and hydrogen peroxide (H2O2), which cause bulky DNA lesions and oxidative DNA damage, respectively. Following exposure to both MeHg and HgCl2, low-level DNA damage (~0.25 lesions/10 kb mtDNA and nDNA) was observed. Unexpectedly, a higher MeHg concentration reduced damage in both genomes compared to controls. However, this observation was likely the result of developmental delay. In co-exposure treatments, both mercury compounds increased initial DNA damage (mtDNA and nDNA) in combination with H2O2 exposure, but had no impact in combination with UVC exposure. Mercury exposure both increased and decreased DNA damage removal via BER. DNA repair after H2O2 exposure in mercury-exposed nematodes resulted in damage levels lower than measured in controls. Impacts to NER were not detected. mtDNA copy number was significantly decreased in the MeHg-UVC and MeHg-H2O2 co-exposure treatments. Mercury exposure had metabolic impacts (steady-state ATP levels) that differed between the compounds; HgCl2 exposure decreased these levels, while MeHg slightly increased levels or had no impact. Both mercury species reduced mRNA levels for immune signaling-related genes, but had mild or no effects on survival on pathogenic bacteria. Overall, mercury exposure disrupted mitochondrial endpoints in a mercury-compound dependent fashion. PMID:28242054

VCP/p97 cooperates with YOD1, UBXD1 and PLAA to drive clearance of ruptured lysosomes by autophagy.

PubMed

Papadopoulos, Chrisovalantis; Kirchner, Philipp; Bug, Monika; Grum, Daniel; Koerver, Lisa; Schulze, Nina; Poehler, Robert; Dressler, Alina; Fengler, Sven; Arhzaouy, Khalid; Lux, Vanda; Ehrmann, Michael; Weihl, Conrad C; Meyer, Hemmo

2017-01-17

Rupture of endosomes and lysosomes is a major cellular stress condition leading to cell death and degeneration. Here, we identified an essential role for the ubiquitin-directed AAA-ATPase, p97, in the clearance of damaged lysosomes by autophagy. Upon damage, p97 translocates to lysosomes and there cooperates with a distinct set of cofactors including UBXD1, PLAA, and the deubiquitinating enzyme YOD1, which we term ELDR components for Endo-Lysosomal Damage Response. Together, they act downstream of K63-linked ubiquitination and p62 recruitment, and selectively remove K48-linked ubiquitin conjugates from a subpopulation of damaged lysosomes to promote autophagosome formation. Lysosomal clearance is also compromised in MEFs harboring a p97 mutation that causes inclusion body myopathy and neurodegeneration, and damaged lysosomes accumulate in affected patient tissue carrying the mutation. Moreover, we show that p97 helps clear late endosomes/lysosomes ruptured by endocytosed tau fibrils. Thus, our data reveal an important mechanism of how p97 maintains lysosomal homeostasis, and implicate the pathway as a modulator of degenerative diseases. © 2016 The Authors.

A novel regulation mechanism of DNA repair by damage-induced and RAD23-dependent stabilization of xeroderma pigmentosum group C protein

PubMed Central

Ng, Jessica M.Y.; Vermeulen, Wim; van der Horst, Gijsbertus T.J.; Bergink, Steven; Sugasawa, Kaoru; Vrieling, Harry; Hoeijmakers, Jan H.J.

2003-01-01

Primary DNA damage sensing in mammalian global genome nucleotide excision repair (GG-NER) is performed by the xeroderma pigmentosum group C (XPC)/HR23B protein complex. HR23B and HR23A are human homologs of the yeast ubiquitin-domain repair factor RAD23, the function of which is unknown. Knockout mice revealed that mHR23A and mHR23B have a fully redundant role in NER, and a partially redundant function in embryonic development. Inactivation of both genes causes embryonic lethality, but appeared still compatible with cellular viability. Analysis of mHR23A/B double-mutant cells showed that HR23 proteins function in NER by governing XPC stability via partial protection against proteasomal degradation. Interestingly, NER-type DNA damage further stabilizes XPC and thereby enhances repair. These findings resolve the primary function of RAD23 in repair and reveal a novel DNA-damage-dependent regulation mechanism of DNA repair in eukaryotes, which may be part of a more global damage-response circuitry. PMID:12815074

Cigarette smoke-induced cell death of a spermatocyte cell line can be prevented by inactivating the Aryl hydrocarbon receptor

PubMed Central

Esakky, P; Hansen, D A; Drury, A M; Cusumano, A; Moley, K H

2015-01-01

Cigarette smoke exposure causes germ cell death during spermatogenesis. Our earlier studies demonstrated that cigarette smoke condensate (CSC) causes spermatocyte cell death in vivo and growth arrest of the mouse spermatocyte cell line (GC-2spd(ts)) in vitro via the aryl hydrocarbon receptor (AHR). We hypothesize here that inactivation of AHR could prevent the CSC-induced cell death in spermatocytes. We demonstrate that CSC exposure generates oxidative stress, which differentially regulates mitochondrial apoptosis in GC-2spd(ts) and wild type (WT) and AHR knockout (AHR-KO) mouse embryonic fibroblasts (MEFs). SiRNA-mediated silencing of Ahr augments the extent of CSC-mediated cellular damage while complementing the AHR-knockout condition. Pharmacological inhibition using the AHR-antagonist (CH223191) modulates the CSC-altered expression of apoptotic proteins and significantly abrogates DNA fragmentation though the cleavage of PARP appears AHR independent. Pretreatment with CH223191 at concentrations above 50 μM significantly prevents the CSC-induced activation of caspase-3/7 and externalization of phosphatidylserine in the plasma membrane. However, MAPK inhibitors alone or together with CH223191 could not prevent the membrane damage upon CSC addition and the caspase-3/7 activation and membrane damage in AHR-deficient MEF indicates the interplay of multiple cell signaling and cytoprotective ability of AHR. Thus the data obtained on one hand signifies the protective role of AHR in maintaining normal cellular homeostasis and the other, could be a potential prophylactic therapeutic target to promote cell survival and growth under cigarette smoke exposed environment by receptor antagonism via CH223191-like mechanism. Antagonist-mediated inactivation of the aryl hydrocarbon receptor blocks downstream events leading to cigarette smoke-induced cell death of a spermatocyte cell line. PMID:27551479

Biomonitoring of DNA damage in peripheral blood lymphocytes of subjects with dental restorative fillings.

PubMed

Di Pietro, Angela; Visalli, Giuseppa; La Maestra, Sebastiano; Micale, Rosanna; Baluce, Barbara; Matarese, Giovanni; Cingano, Luciano; Scoglio, Maria Elena

2008-02-29

Dental fillings provide a major iatrogenic exposure to xenobiotic compounds due to the high prevalence of surface restorations in developed countries. Experimental data suggest that both amalgams, which contain mercury, and resin-based dental materials cause an impairment of the cellular pro- and anti-oxidant redox balance. The aim of this study was to assess the potential genotoxicity of dental restorative compounds in peripheral blood lymphocytes of young exposed subjects compared with controls. The study examined, by use of the comet assay, 68 carefully selected subjects taking into account the major known confounding factors. In the 44 exposed subjects, the mean numbers of restored surfaces was 3.0 and 3.8 in males and females, respectively. Tail length, percentage of DNA in the tail, tail moment or Olive tail moment were twofold higher in the exposed group than in unexposed controls, with significant differences. No significant difference was observed between amalgam and composite fillings. Furthermore, as shown by multivariate analysis, the association between dental fillings and DNA damage was enhanced by the number of fillings and by the exposure time. Among the lifestyle variables, a moderate physical activity showed a protective effect, being inversely correlated to the DNA damage parameters evaluated. On the whole, the use of DNA-migration allowed us to detect for the first time the potential adverse impact on human health of both kinds of dental filling constituents, the amalgams and the methacrylates. The main mechanism underlying the genotoxicity of dental restorative materials of various nature may be ascribed to the ability of both amalgams and methacrylates to trigger the generation of cellular reactive oxygen species, able to cause oxidative DNA lesions.

Generating an agricultural risk map based on limited ecological information: A case study using Sicyos angulatus.

PubMed

Osawa, Takeshi; Okawa, Shigenori; Kurokawa, Shunji; Ando, Shinichiro

2016-12-01

In this study, we propose a method for estimating the risk of agricultural damage caused by an invasive species when species-specific information is lacking. We defined the "risk" as the product of the invasion probability and the area of potentially damaged crop for production. As a case study, we estimated the risk imposed by an invasive weed, Sicyos angulatus, based on simple cellular simulations and governmental data on the area of crop that could potentially be damaged in Miyagi Prefecture, Japan. Simulation results revealed that the current distribution range was sufficiently accurate for practical purposes. Using these results and records of crop areas, we present risk maps for S. angulatus in agricultural fields. Managers will be able to use these maps to rapidly establish a management plan with minimal cost. Our approach will be valuable for establishing a management plan before or during the early stages of invasion.

Homeodomain-Interacting Protein Kinase-2: A Critical Regulator of the DNA Damage Response and the Epigenome

PubMed Central

Kuwano, Yuki; Nishida, Kensei; Akaike, Yoko; Kurokawa, Ken; Nishikawa, Tatsuya; Masuda, Kiyoshi; Rokutan, Kazuhito

2016-01-01

Homeodomain-interacting protein kinase 2 (HIPK2) is a serine/threonine kinase that phosphorylates and activates the apoptotic program through interaction with diverse downstream targets including tumor suppressor p53. HIPK2 is activated by genotoxic stimuli and modulates cell fate following DNA damage. The DNA damage response (DDR) is triggered by DNA lesions or chromatin alterations. The DDR regulates DNA repair, cell cycle checkpoint activation, and apoptosis to restore genome integrity and cellular homeostasis. Maintenance of the DDR is essential to prevent development of diseases caused by genomic instability, including cancer, defects of development, and neurodegenerative disorders. Recent studies reveal a novel HIPK2-mediated pathway for DDR through interaction with chromatin remodeling factor homeodomain protein 1γ. In this review, we will highlight the molecular mechanisms of HIPK2 and show its functions as a crucial DDR regulator. PMID:27689990

Complex DNA Damage: A Route to Radiation-Induced Genomic Instability and Carcinogenesis

PubMed Central

Mavragani, Ifigeneia V.; Nikitaki, Zacharenia; Souli, Maria P.; Aziz, Asef; Nowsheen, Somaira; Aziz, Khaled; Rogakou, Emmy

2017-01-01

Cellular effects of ionizing radiation (IR) are of great variety and level, but they are mainly damaging since radiation can perturb all important components of the cell, from the membrane to the nucleus, due to alteration of different biological molecules ranging from lipids to proteins or DNA. Regarding DNA damage, which is the main focus of this review, as well as its repair, all current knowledge indicates that IR-induced DNA damage is always more complex than the corresponding endogenous damage resulting from endogenous oxidative stress. Specifically, it is expected that IR will create clusters of damage comprised of a diversity of DNA lesions like double strand breaks (DSBs), single strand breaks (SSBs) and base lesions within a short DNA region of up to 15–20 bp. Recent data from our groups and others support two main notions, that these damaged clusters are: (1) repair resistant, increasing genomic instability (GI) and malignant transformation and (2) can be considered as persistent “danger” signals promoting chronic inflammation and immune response, causing detrimental effects to the organism (like radiation toxicity). Last but not least, the paradigm shift for the role of radiation-induced systemic effects is also incorporated in this picture of IR-effects and consequences of complex DNA damage induction and its erroneous repair. PMID:28718816

Complex DNA Damage: A Route to Radiation-Induced Genomic Instability and Carcinogenesis.

PubMed

Mavragani, Ifigeneia V; Nikitaki, Zacharenia; Souli, Maria P; Aziz, Asef; Nowsheen, Somaira; Aziz, Khaled; Rogakou, Emmy; Georgakilas, Alexandros G

2017-07-18

Cellular effects of ionizing radiation (IR) are of great variety and level, but they are mainly damaging since radiation can perturb all important components of the cell, from the membrane to the nucleus, due to alteration of different biological molecules ranging from lipids to proteins or DNA. Regarding DNA damage, which is the main focus of this review, as well as its repair, all current knowledge indicates that IR-induced DNA damage is always more complex than the corresponding endogenous damage resulting from endogenous oxidative stress. Specifically, it is expected that IR will create clusters of damage comprised of a diversity of DNA lesions like double strand breaks (DSBs), single strand breaks (SSBs) and base lesions within a short DNA region of up to 15-20 bp. Recent data from our groups and others support two main notions, that these damaged clusters are: (1) repair resistant, increasing genomic instability (GI) and malignant transformation and (2) can be considered as persistent "danger" signals promoting chronic inflammation and immune response, causing detrimental effects to the organism (like radiation toxicity). Last but not least, the paradigm shift for the role of radiation-induced systemic effects is also incorporated in this picture of IR-effects and consequences of complex DNA damage induction and its erroneous repair.

Chronic Oxidative Damage together with Genome Repair Deficiency in the Neurons is a Double Whammy for Neurodegeneration: Is Damage Response Signaling a Potential Therapeutic Target?

PubMed Central

Wang, Haibo; Dharmalingam, Prakash; Vasquez, Velmarini; Mitra, Joy; Boldogh, Istvan; Rao, K. S.; Kent, Thomas A.; Mitra, Sankar; Hegde, Muralidhar L.

2016-01-01

A foremost challenge for the neurons, which are among the most oxygenated cells, is the genome damage caused by chronic exposure to endogenous reactive oxygen species (ROS), formed as cellular respiratory byproducts. Strong metabolic activity associated with high transcriptional levels in these long lived post-mitotic cells render them vulnerable to oxidative genome damage, including DNA strand breaks and mutagenic base lesions. There is growing evidence for the accumulation of unrepaired DNA lesions in the central nervous system (CNS) during accelerated ageing and progressive neurodegeneration. Several germ line mutations in DNA repair or DNA damage response (DDR) signaling genes are uniquely manifested in the phenotype of neuronal dysfunction and are etiologically linked to many neurodegenerative disorders. Studies in our lab and elsewhere revealed that pro-oxidant metals, ROS and misfolded amyloidogenic proteins not only contribute to genome damage in CNS, but also impede their repair/DDR signaling leading to persistent damage accumulation, a common feature in sporadic neurodegeneration. Here, we have reviewed recent advances in our understanding of the etiological implications of DNA damage vs. repair imbalance, abnormal DDR signaling in triggering neurodegeneration and potential of DDR as a target for the amelioration of neurodegenerative diseases. PMID:27663141

Environmental pollutants and lifestyle factors induce oxidative stress and poor prenatal development.

PubMed

Al-Gubory, Kaïs H

2014-07-01

Developmental toxicity caused by exposure to a mixture of environmental pollutants has become a major health concern. Human-made chemicals, including xenoestrogens, pesticides and heavy metals, as well as unhealthy lifestyle behaviours, mainly tobacco smoking, alcohol consumption and medical drug abuse, are major factors that adversely influence prenatal development and increase susceptibility of offspring to diseases. There is evidence to suggest that the developmental toxicological mechanisms of chemicals and lifestyle factors involve the generation of reactive oxygen species (ROS) and cellular oxidative damage. Overproduction of ROS induces oxidative stress, a state where increased ROS generation overwhelms antioxidant protection and subsequently leads to oxidative damage of cellular macromolecules. Data on the involvement of oxidative stress in the mechanism of developmental toxicity following exposure to environmental pollutants are reviewed in an attempt to provide an updated basis for future studies on the toxic effect of such pollutants, particularly the notion of increased risk for developmental toxicity due to combined and cumulative exposure to various environmental pollutants. The aims of such studies are to better understand the mechanisms by which environmental pollutants adversely affect conceptus development and to elucidate the impact of cumulative exposures to multiple pollutants on post-natal development and health outcomes. Developmental toxicity caused by exposure to mixture of environmental pollutants has become a major health concern. Human-made chemicals, including xenoestrogens, pesticides and heavy metals, as well as unhealthy lifestyle behaviors, mainly tobacco smoking, alcohol consumption and medical drug abuse, are major factors that adversely influence prenatal development and increase the susceptibility of offspring to development complications and diseases. There is evidence to suggest that the developmental toxicological mechanisms of human-made chemicals and unhealthy lifestyle factors involve the generation of reactive oxygen species (ROS) and cellular oxidative damage. Overproduction of ROS induces oxidative stress, a state where increased generation of ROS overwhelms antioxidant protection and subsequently leads to oxidative damage of cellular macromolecules. Exposure to various environmental pollutants induces synergic and cumulative dose-additive adverse effects on prenatal development, pregnancy outcomes and neonate health. Data from the literature on the involvement of oxidative stress in the mechanism of developmental toxicity following in vivo exposure to environmental pollutants will be reviewed in an attempt to provide an updated basis for future studies on the toxic effect of such pollutants, particularly the notion of increased risk for developmental toxicity due to combined and cumulative exposure to various environmental pollutants. The aims of such studies are to better understand the mechanisms by which environmental pollutants adversely affect conceptus development and to elucidate the impact of cumulative exposures to multiple pollutants on postnatal development and health outcomes. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Herpesviruses and Their Host Cells: A Successful Liaison.

PubMed

Adler, Barbara; Sattler, Christine; Adler, Heiko

2017-03-01

During a long history of coevolution, herpesviruses have reached a fine-tuned balance with their hosts, allowing them to successfully persist and spread to new hosts without causing too much damage. Only under certain circumstances, as in neonates or immunocompromised individuals, they may cause serious diseases. The delicate balance between herpesviruses and their hosts results from interactions of a great variety of viral and cellular factors which together shape the tropism for a particular host, tissue, or cell. Understanding these interactions will provide insight into the viral life cycle and cell biology in general. Moreover, it will also facilitate comprehension of herpesvirus pathogenesis, enabling the development of new strategies to combat herpesviruses in cases where they cause disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Early metabolic responses to lithium/pilocarpine-induced status epilepticus in rat brain.

PubMed

Imran, Imran; Hillert, Markus H; Klein, Jochen

2015-12-01

The lithium-pilocarpine model of status epilepticus is a well-known animal model of temporal lobe epilepsy. We combined this model with in vivo microdialysis to investigate energy metabolites and acute cellular membrane damage during seizure development. Rats were implanted with dialysis probes and pretreated with lithium chloride (127 mg/kg i.p.). Twenty-four hours later, they received pilocarpine (30 mg/kg s.c.) which initiated seizures within 30 min. In the dialysate from rat hippocampus, we observed a transient increase in glucose and a prominent, five-fold increase in lactate during seizures. Lactate release was because of neuronal activation as it was strongly reduced by infusion of tetrodotoxin, administration of atropine or when seizures were terminated by diazepam or ketamine. In ex vivo assays, mitochondrial function as measured by respirometry was not affected by 90 min of seizures. Extracellular levels of choline, however, increased two-fold and glycerol levels 10-fold, which indicate cellular phospholipid breakdown during seizures. Within 60 min of pilocarpine administration, hydroxylation of salicylate increased two-fold and formation of isoprostanes 20-fold, revealing significant oxidative stress in hippocampal tissue. Increases in lactate, glycerol and isoprostanes were abrogated, and increases in choline were completely prevented, when hippocampal probes were perfused with calcium-free solution. Similarly, administration of pregabalin (100 mg/kg i.p.), a calcium channel ligand, 15 min prior to pilocarpine strongly attenuated parameters of membrane damage and oxidative stress. We conclude that seizure development in a rat model of status epilepticus is accompanied by increases in extracellular lactate, choline and glycerol, and by oxidative stress, while mitochondrial function remains intact for at least 90 min. Membrane damage depends on calcium influx and can be prevented by treatment with pregabalin. Status epilepticus (SE) was induced in rats by lithium-pilocarpine ('Pilo') administration, and extracellular metabolites were measured by microdialysis. Seizures caused several-fold increases in lactate levels which were attenuated by diazepam ('Diaz'), ketamine, atropine and tetrodotoxin (TTX). Indicators of oxidative stress and membrane damage were also increased during seizures. Omission of calcium and pregabalin, a calcium channel blocker, reduced cellular damage induced by SE. © 2015 International Society for Neurochemistry.

Oxidation in the nucleotide pool, the DNA damage response and cellular senescence: Defective bricks build a defective house.

PubMed

Rai, Priyamvada

2010-11-28

Activation of persistent DNA damage response (DDR) signaling is associated with the induction of a permanent proliferative arrest known as cellular senescence, a phenomenon intrinsically linked to both tissue aging as well as tumor suppression. The DNA damage observed in senescent cells has been attributed to elevated levels of reactive oxygen species (ROS), failing DNA damage repair processes, and/or oncogenic activation. It is not clear how labile molecules such as ROS are able to damage chromatin-bound DNA to a sufficient extent to invoke persistent DNA damage and DDR signaling. Recent evidence suggests that the nucleotide pool is a significant target for oxidants and that oxidized nucleotides, once incorporated into genomic DNA, can lead to the induction of a DNA strand break-associated DDR that triggers senescence in normal cells and in cells sustaining oncogene activation. Evasion of this DDR and resulting senescence is a key step in tumor progression. This review will explore the role of oxidation in the nucleotide pool as a major effector of oxidative stress-induced genotoxic damage and DDR in the context of cellular senescence and tumorigenic transformation. 2010 Elsevier B.V. All rights reserved.

The effect of hyperthermia on the radiation response of crypt cells in mouse jejunum

NASA Technical Reports Server (NTRS)

Wilson, J. D.

1978-01-01

The effect of hyperthermia and/or gamma-radiation on the survival of intestinal crypt cells was studied in BDF sub 1 mice using a microcolony assay. Hyperthermia treatments, which in themselves caused no detectable cell lethality, inhibited the capacity of crypt cells to repair sublethal radiation damage. In addition, heat applied either before or after single radiation exposures potentiated lethal damage to crypt cells; the degree of enhancement was dependent on the time interval between treatments. At the levels of heating employed, DNA synthesis in the intestinal epithelium was significantly reduced immediately following exposure, but returned rapidly to normal levels. No further disturbances in cellular kinetics were observed for up to 10 days after heating.

Antioxidants and the Integrity of Ocular Tissues

PubMed Central

Cabrera, Marcela P.; Chihuailaf, Ricardo H.

2011-01-01

Oxygen-derived free radicals are normally generated in many pathways. These radicals can interact with various cellular components and induce cell injury. When free radicals exceed the antioxidant capacity, cell injury causes diverse pathologic changes in the organs. The imbalance between the generation of free radicals and antioxidant defence is known as oxidative stress. The eye can suffer the effect of oxidative damage due to the etiopathogenesis of some pathological changes related to oxidative stress. This paper reviews the role of oxidative stress in the onset and progression of damage in different eye structures, the involvement of the antioxidant network in protecting and maintaining the homeostasis of this organ, and the potential assessment methodologies used in research and in some cases in clinical practice. PMID:21789267

Radiation-induced cardiovascular effects

NASA Astrophysics Data System (ADS)

Tapio, Soile

Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

Heat shock-initiated apoptosis is accelerated and removal of damaged cells is delayed in the testis of clusterin/ApoJ knock-out mice.

PubMed

Bailey, Robert W; Aronow, Bruce; Harmony, Judith A K; Griswold, Michael D

2002-04-01

The secretion and localization of clusterin in the testis has led to the hypothesis that clusterin plays a role in spermatogenesis. Furthermore, the association of clusterin with apoptosis, cellular injury, disease, and regression of nongonadal tissues has led to the hypothesis that clusterin acts to protect cells from apoptosis or may be involved in tissue remodeling. To investigate the role of clusterin in the testis, we analyzed clusterin knock-out (cluKO) mice to determine the impact of the absence of clusterin on spermatogenesis. Furthermore, we investigated the cellular response to injury caused by methoxyacetic acid (MAA) toxicity and mild heat exposure in the cluKO mice to determine the extent to which clusterin protects against apoptosis or participates in tissue remodeling. We found that cluKO mice were fertile and had essentially normal spermatogenesis with the exception of some incomplete spermiation after stage VIII. No differences in testicular morphology or the incidence of apoptosis in the testis were seen between the cluKO and clusterin wild-type (cluWT) mice after MAA treatment. In contrast, apoptosis was delayed in the cluWT mice compared with the cluKO mice after heat exposure, suggesting that clusterin does have a slight protective effect against apoptosis under some conditions. Also, a dramatic loss of germ cells after heat stress occurred earlier in the cluWT testes than in the cluKO testes. Clusterin is clearly acting in a dual role in that cells can be protected from damage and dead cells can be more easily removed after some types of cellular damage but not after others.

Differential Activation of Cellular DNA Damage Responses by Replication-Defective and Replication-Competent Adenovirus Mutants

PubMed Central

Prakash, Anand; Jayaram, Sumithra

2012-01-01

Adenovirus (Ad) mutants that lack early region 4 (E4) activate the phosphorylation of cellular DNA damage response proteins. In wild-type Ad type 5 (Ad5) infections, E1b and E4 proteins target the cellular DNA repair protein Mre11 for redistribution and degradation, thereby interfering with its ability to activate phosphorylation cascades important during DNA repair. The characteristics of Ad infection that activate cellular DNA repair processes are not yet well understood. We investigated the activation of DNA damage responses by a replication-defective Ad vector (AdRSVβgal) that lacks E1 and fails to produce the immediate-early E1a protein. E1a is important for activating early gene expression from the other viral early transcription units, including E4. AdRSVβgal can deliver its genome to the cell, but it is subsequently deficient for viral early gene expression and DNA replication. We studied the ability of AdRSVβgal-infected cells to induce cellular DNA damage responses. AdRSVβgal infection does activate formation of foci containing the Mdc1 protein. However, AdRSVβgal fails to activate phosphorylation of the damage response proteins Nbs1 and Chk1. We found that viral DNA replication is important for Nbs1 phosphorylation, suggesting that this step in the viral life cycle may provide an important trigger for activating at least some DNA repair proteins. PMID:23015708

Plant Nucleolar Stress Response, a New Face in the NAC-Dependent Cellular Stress Responses.

PubMed

Ohbayashi, Iwai; Sugiyama, Munetaka

2017-01-01

The nucleolus is the most prominent nuclear domain, where the core processes of ribosome biogenesis occur vigorously. All these processes are finely orchestrated by many nucleolar factors to build precisely ribosome particles. In animal cells, perturbations of ribosome biogenesis, mostly accompanied by structural disorders of the nucleolus, cause a kind of cellular stress to induce cell cycle arrest, senescence, or apoptosis, which is called nucleolar stress response. The best-characterized pathway of this stress response involves p53 and MDM2 as key players. p53 is a crucial transcription factor that functions in response to not only nucleolar stress but also other cellular stresses such as DNA damage stress. These cellular stresses release p53 from the inhibition by MDM2, an E3 ubiquitin ligase targeting p53, in various ways, which leads to p53-dependent activation of a set of genes. In plants, genetic impairments of ribosome biogenesis factors or ribosome components have been shown to cause characteristic phenotypes, including a narrow and pointed leaf shape, implying a common signaling pathway connecting ribosomal perturbations and certain aspects of growth and development. Unlike animals, however, plants have neither p53 nor MDM2 family proteins. Then the question arises whether plant cells have a nucleolar stress response pathway. In recent years, it has been reported that several members of the plant-specific transcription factor family NAC play critical roles in the pathways responsive to various cellular stresses. In this mini review, we outline the plant cellular stress response pathways involving NAC transcription factors with reference to the p53-MDM2-dependent pathways of animal cells, and discuss the possible involvement of a plant-unique, NAC-mediated pathway in the nucleolar stress response in plants.

Peroxisomes contribute to oxidative stress in neurons during doxorubicin-based chemotherapy.

PubMed

Moruno-Manchon, Jose F; Uzor, Ndidi-Ese; Kesler, Shelli R; Wefel, Jeffrey S; Townley, Debra M; Nagaraja, Archana Sidalaghatta; Pradeep, Sunila; Mangala, Lingegowda S; Sood, Anil K; Tsvetkov, Andrey S

2018-01-01

Doxorubicin, a commonly used anti-neoplastic agent, causes severe neurotoxicity. Doxorubicin promotes thinning of the brain cortex and accelerates brain aging, leading to cognitive impairment. Oxidative stress induced by doxorubicin contributes to cellular damage. In addition to mitochondria, peroxisomes also generate reactive oxygen species (ROS) and promote cell senescence. Here, we investigated if doxorubicin affects peroxisomal homeostasis in neurons. We demonstrate that the number of peroxisomes is increased in doxorubicin-treated neurons and in the brains of mice which underwent doxorubicin-based chemotherapy. Pexophagy, the specific autophagy of peroxisomes, is downregulated in neurons, and peroxisomes produce more ROS. 2-hydroxypropyl-β-cyclodextrin (HPβCD), an activator of the transcription factor TFEB, which regulates expression of genes involved in autophagy and lysosome function, mitigates damage of pexophagy and decreases ROS production induced by doxorubicin. We conclude that peroxisome-associated oxidative stress induced by doxorubicin may contribute to neurotoxicity, cognitive dysfunction, and accelerated brain aging in cancer patients and survivors. Peroxisomes might be a valuable new target for mitigating neuronal damage caused by chemotherapy drugs and for slowing down brain aging in general. Copyright © 2017 Elsevier Inc. All rights reserved.

Metallic ions released from stainless steel, nickel-free, and titanium orthodontic alloys: toxicity and DNA damage.

PubMed

Ortiz, Antonio José; Fernández, Esther; Vicente, Ascensión; Calvo, José L; Ortiz, Clara

2011-09-01

The aims of this study were to determine the amounts of metallic ions that stainless steel, nickel-free, and titanium alloys release to a culture medium, and to evaluate the cellular viability and DNA damage of cultivated human fibroblasts with those mediums. The metals were extracted from 10 samples (each consisting of 4 buccal tubes and 20 brackets) of the 3 orthodontic alloys that were submerged for 30 days in minimum essential medium. Next, the determination of metals was performed by using inductively coupled plasma mass spectrometry, cellular viability was assessed by using the tetrazolium reduction assay (MTT assay) (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide), and DNA damage was determined with the Comet assay. The metals measured in all the samples were Ti(47), Cr(52), Mn(55), Co(59), Ni(60), Mo(92), Fe(56), Cu(63), Zn(66), As(75), Se(78), Cd(111), and Pb(208). The cellular viability of the cultured fibroblasts incubated for 7 days with minimum essential medium, with the stainless steel alloy submerged, was close to 0%. Moreover, high concentrations of titanium, chromium, manganese, cobalt, nickel, molybdenum, iron, copper, and zinc were detected. The nickel-free alloy released lower amounts of ions to the medium. The greatest damage in the cellular DNA, measured as the olive moment, was also produced by the stainless steel alloy followed by the nickel-free alloy. Conversely, the titanium alloy had an increased cellular viability and did not damage the cellular DNA, as compared with the control values. The titanium brackets and tubes are the most biocompatible of the 3 alloys studied. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Infusion pumps and red blood cell damage in transfusion therapy: an integrative revision of the academic literature 1

PubMed Central

Wilson, Ana Maria Miranda Martins; Peterlini, Maria Angélica Sorgini; Pedreira, Mavilde da Luz Gonçalves

2016-01-01

ABSTRACT Objectives: to obtain information from scientific literature concerning infusion pumps used in administering erythrocyte (red blood cells) and to evaluate the implications in the practical use of this equipment by nurses when conducting transfusions. Method: an integrative revision of the following scientific databases: Pubmed/Medline, Scopus, the Virtual Library for Health, SciELO, Web of Science and Cochrane. The following descriptors were used: "infusion pumps", "blood transfusion", "transfused erythrocyte" and "hemolyis". There were no restrictions on the scope of the initial data and it was finalized in December 2014. 17 articles were identified in accordance with the inclusion and exclusion criteria. Results: all of the publications included in the studies were experimental in vitro and covered the use of infusion pumps in transfusion therapy. A summary of the data was presented in a synoptic chart and an analysis of it generated the following categories: cellular damage and the infusion mechanism. Conclusion: infusion pumps can be harmful to erythrocytes based on the infusion mechanism that is used, as the linear peristaltic pump is more likely to cause hemolysis. Cellular damage is related to the plasmatic liberation of markers that largely dominate free hemoglobin and potassium. We reiterate the need for further research and technological investments to guide the development of protocols that promote safe practices and that can contribute to future clinical studies. PMID:27533272

Effect of ionizing radiation on the physical biology of head and neck squamous cell carcinoma cells.

PubMed

Baker-Groberg, Sandra M; Bornstein, Sophia; Zilberman-Rudenko, Jevgenia; Schmidt, Mark; Tormoen, Garth W; Kernan, Casey; Thomas, Charles R; Wong, Melissa H; Phillips, Kevin G; McCarty, Owen J T

2015-09-01

Head and neck squamous cell carcinoma (HNSCC) is the sixth leading cause of cancer worldwide. Although there are numerous treatment options for HNSCC, such as surgery, cytotoxic chemotherapy, molecularly targeted systemic therapeutics, and radiotherapy, overall survival has not significantly improved in the last 50 years. This suggests a need for a better understanding of how these cancer cells respond to current treatments in order to improve treatment paradigms. Ionizing radiation (IR) promotes cancer cell death through the creation of cytotoxic DNA lesions, including single strand breaks, base damage, crosslinks, and double strand breaks (DSBs). As unrepaired DSBs are the most cytotoxic DNA lesion, defining the downstream cellular responses to DSBs are critical for understanding the mechanisms of tumor cell responses to IR. The effects of experimental IR on HNSCC cells beyond DNA damage in vitro are ill-defined. Here we combined label-free, quantitative phase and fluorescent microscopy to define the effects of IR on the dry mass and volume of the HNSCC cell line, UM-SCC-22A. We quantified nuclear and cytoplasmic subcellular density alterations resulting from 8 Gy X-ray IR and correlated these signatures with DNA and γ-H2AX expression patterns. This study utilizes a synergistic imaging approach to study both biophysical and biochemical alterations in cells following radiation damage and will aid in future understanding of cellular responses to radiation therapy.

Single-molecule localization microscopy reveals molecular transactions during RAD51 filament assembly at cellular DNA damage sites

PubMed Central

Haas, Kalina T; Lee, MiYoung; Esposito, Alessandro; Venkitaraman, Ashok R

2018-01-01

Abstract RAD51 recombinase assembles on single-stranded (ss)DNA substrates exposed by DNA end-resection to initiate homologous recombination (HR), a process fundamental to genome integrity. RAD51 assembly has been characterized using purified proteins, but its ultrastructural topography in the cell nucleus is unexplored. Here, we combine cell genetics with single-molecule localization microscopy and a palette of bespoke analytical tools, to visualize molecular transactions during RAD51 assembly in the cellular milieu at resolutions approaching 30–40 nm. In several human cell types, RAD51 focalizes in clusters that progressively extend into long filaments, which abut—but do not overlap—with globular bundles of replication protein A (RPA). Extended filaments alter topographically over time, suggestive of succeeding steps in HR. In cells depleted of the tumor suppressor protein BRCA2, or overexpressing its RAD51-binding BRC repeats, RAD51 fails to assemble at damage sites, although RPA accumulates unhindered. By contrast, in cells lacking a BRCA2 carboxyl (C)-terminal region targeted by cancer-causing mutations, damage-induced RAD51 assemblies initiate but do not extend into filaments. We suggest a model wherein RAD51 assembly proceeds concurrently with end-resection at adjacent sites, via an initiation step dependent on the BRC repeats, followed by filament extension through the C-terminal region of BRCA2. PMID:29309696

Multiscale modelling of Flow-Induced Blood Cell Damage

NASA Astrophysics Data System (ADS)

Liu, Yaling; Sohrabi, Salman

2017-11-01

We study red blood cell (RBC) damage and hemolysis at cellular level. Under high shear rates, pores form on RBC membranes through which hemoglobin (Hb) leaks out and increases free Hb content of plasma leading to hemolysis. By coupling lattice Boltzmann and spring connected network models through immersed boundary method, we estimate hemolysis of a single RBC under various shear rates. The developed cellular damage model can be used as a predictive tool for hydrodynamic and hematologic design optimization of blood-wetting medical devices.

Phospholipid alterations in the brain and heart in a rat model of asphyxia-induced cardiac arrest and cardiopulmonary bypass resuscitation

PubMed Central

Kim, Junhwan; Lampe, Joshua W.; Yin, Tai; Shinozaki, Koichiro; Becker, Lance B.

2015-01-01

Cardiac arrest (CA) induces whole-body ischemia, causing damage to multiple organs. Ischemic damage to the brain is mainly responsible for patient mortality. However, the molecular mechanism responsible for brain damage is not understood. Prior studies have provided evidence that degradation of membrane phospholipids plays key roles in ischemia/reperfusion injury. The aim of this study is to correlate organ damage to phospholipid alterations following 30 min asphyxia-induced CA or CA followed by cardiopulmonary bypass (CPB) resuscitation using a rat model. Following 30 min CA and CPB resuscitation, rats showed no brain function, moderately compromised heart function, and died within a few hours; typical outcomes of severe CA. However, we did not find any significant change in the content or composition of phospholipids in either tissue following 30 min CA or CA followed by CPB resuscitation. We found a moderate increase in lysophosphatidylinositol in both tissues, and a small increase in lysophosphatidylethanolamine and lysophosphatidylcholine only in brain tissue following CA. CPB resuscitation significantly decreased lysophosphatidylinositol but did not alter the other lyso species. These results indicate that a decrease in phospholipids is not a cause of brain damage in CA or a characteristic of brain ischemia. However, a significant increase in lysophosphatidylcholine and lysophosphatidylethanolamine found only in the brain with more damage suggests that impaired phospholipid metabolism may be correlated with the severity of ischemia in CA. In addition, the unique response of lysophosphatidylinositol suggests that phosphatidylinositol metabolism is highly sensitive to cellular conditions altered by ischemia and resuscitation. PMID:26160279

Phospholipid alterations in the brain and heart in a rat model of asphyxia-induced cardiac arrest and cardiopulmonary bypass resuscitation.

PubMed

Kim, Junhwan; Lampe, Joshua W; Yin, Tai; Shinozaki, Koichiro; Becker, Lance B

2015-10-01

Cardiac arrest (CA) induces whole-body ischemia, causing damage to multiple organs. Ischemic damage to the brain is mainly responsible for patient mortality. However, the molecular mechanism responsible for brain damage is not understood. Prior studies have provided evidence that degradation of membrane phospholipids plays key roles in ischemia/reperfusion injury. The aim of this study is to correlate organ damage to phospholipid alterations following 30 min asphyxia-induced CA or CA followed by cardiopulmonary bypass (CPB) resuscitation using a rat model. Following 30 min CA and CPB resuscitation, rats showed no brain function, moderately compromised heart function, and died within a few hours; typical outcomes of severe CA. However, we did not find any significant change in the content or composition of phospholipids in either tissue following 30 min CA or CA followed by CPB resuscitation. We found a substantial increase in lysophosphatidylinositol in both tissues, and a small increase in lysophosphatidylethanolamine and lysophosphatidylcholine only in brain tissue following CA. CPB resuscitation significantly decreased lysophosphatidylinositol but did not alter the other lyso species. These results indicate that a decrease in phospholipids is not a cause of brain damage in CA or a characteristic of brain ischemia. However, a significant increase in lysophosphatidylcholine and lysophosphatidylethanolamine found only in the brain with more damage suggests that impaired phospholipid metabolism may be correlated with the severity of ischemia in CA. In addition, the unique response of lysophosphatidylinositol suggests that phosphatidylinositol metabolism is highly sensitive to cellular conditions altered by ischemia and resuscitation.

Blockade of TLR3 protects mice from lethal radiation-induced gastrointestinal syndrome

PubMed Central

Takemura, Naoki; Kawasaki, Takumi; Kunisawa, Jun; Sato, Shintaro; Lamichhane, Aayam; Kobiyama, Kouji; Aoshi, Taiki; Ito, Junichi; Mizuguchi, Kenji; Karuppuchamy, Thangaraj; Matsunaga, Kouta; Miyatake, Shoichiro; Mori, Nobuko; Tsujimura, Tohru; Satoh, Takashi; Kumagai, Yutaro; Kawai, Taro; Standley, Daron M.; Ishii, Ken J.; Kiyono, Hiroshi; Akira, Shizuo; Uematsu, Satoshi

2014-01-01

High-dose ionizing radiation induces severe DNA damage in the epithelial stem cells in small intestinal crypts and causes gastrointestinal syndrome (GIS). Although the tumour suppressor p53 is a primary factor inducing death of crypt cells with DNA damage, its essential role in maintaining genome stability means inhibiting p53 to prevent GIS is not a viable strategy. Here we show that the innate immune receptor Toll-like receptor 3 (TLR3) is critical for the pathogenesis of GIS. Tlr3−/− mice show substantial resistance to GIS owing to significantly reduced radiation-induced crypt cell death. Despite showing reduced crypt cell death, p53-dependent crypt cell death is not impaired in Tlr3−/− mice. p53-dependent crypt cell death causes leakage of cellular RNA, which induces extensive cell death via TLR3. An inhibitor of TLR3–RNA binding ameliorates GIS by reducing crypt cell death. Thus, we propose blocking TLR3 activation as a novel approach to treat GIS. PMID:24637670

Watson-Crick Base Pair Radical Cation as a Model for Oxidative Damage in DNA.

PubMed

Feketeová, Linda; Chan, Bun; Khairallah, George N; Steinmetz, Vincent; Maitre, Philippe; Radom, Leo; O'Hair, Richard A J

2017-07-06

The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson-Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

Mutant SOD1 in cell types other than motor neurons and oligodendrocytes accelerates onset of disease in ALS mice

PubMed Central

Yamanaka, Koji; Boillee, Severine; Roberts, Elizabeth A.; Garcia, Michael L.; McAlonis-Downes, Melissa; Mikse, Oliver R.; Cleveland, Don W.; Goldstein, Lawrence S. B.

2008-01-01

Dominant mutations in ubiquitously expressed superoxide dismutase (SOD1) cause familial ALS by provoking premature death of adult motor neurons. To test whether mutant damage to cell types beyond motor neurons is required for the onset of motor neuron disease, we generated chimeric mice in which all motor neurons and oligodendrocytes expressed mutant SOD1 at a level sufficient to cause fatal, early-onset motor neuron disease when expressed ubiquitously, but did so in a cellular environment containing variable numbers of non-mutant, non-motor neurons. Despite high-level mutant expression within 100% of motor neurons and oligodendrocytes, in most of these chimeras, the presence of WT non-motor neurons substantially delayed onset of motor neuron degeneration, increasing disease-free life by 50%. Disease onset is therefore non-cell autonomous, and mutant SOD1 damage within cell types other than motor neurons and oligodendrocytes is a central contributor to initiation of motor neuron degeneration. PMID:18492803

Cellular and epigenetic drivers of stem cell ageing.

PubMed

Ermolaeva, Maria; Neri, Francesco; Ori, Alessandro; Rudolph, K Lenhard

2018-06-01

Adult tissue stem cells have a pivotal role in tissue maintenance and regeneration throughout the lifespan of multicellular organisms. Loss of tissue homeostasis during post-reproductive lifespan is caused, at least in part, by a decline in stem cell function and is associated with an increased incidence of diseases. Hallmarks of ageing include the accumulation of molecular damage, failure of quality control systems, metabolic changes and alterations in epigenome stability. In this Review, we discuss recent evidence in support of a novel concept whereby cell-intrinsic damage that accumulates during ageing and cell-extrinsic changes in ageing stem cell niches and the blood result in modifications of the stem cell epigenome. These cumulative epigenetic alterations in stem cells might be the cause of the deregulation of developmental pathways seen during ageing. In turn, they could confer a selective advantage to mutant and epigenetically drifted stem cells with altered self-renewal and functions, which contribute to the development of ageing-associated organ dysfunction and disease.

Statin-induced muscle damage and atrogin-1 induction is the result of a geranylgeranylation defect

PubMed Central

Cao, Peirang; Hanai, Jun-ichi; Tanksale, Preeti; Imamura, Shintaro; Sukhatme, Vikas P.; Lecker, Stewart H.

2009-01-01

Statins are widely used to treat hypercholesterolemia but can lead to a number of side effects in muscle, including rhabdomyolysis. Our recent findings implicated the induction of atrogin-1, a gene required for the development of muscle atrophy, in statin-induced muscle damage. Since statins inhibit many biochemical reactions besides cholesterol synthesis, we sought to define the statin-inhibited pathways responsible for atrogin-1 expression and muscle damage. We report here that lovastatin-induced atrogin-1 expression and muscle damage in cultured mouse myotubes and zebrafish can be prevented in the presence of geranylgeranol but not farnesol. Further, inhibitors of the transfer of geranylgeranyl isoprene units to protein targets cause statin muscle damage and atrogin-1 induction in cultured cells and in fish. These findings support the concept that dysfunction of small GTP-binding proteins lead to statin-induced muscle damage since these molecules require modification by geranylgeranyl moieties for their cellular localization and activity. Collectively, our animal and in vitro findings shed light on the molecular mechanism of statin-induced myopathy and suggest that atrogin-1 may be regulated by novel signaling pathways.—Cao, P., Hanai, J., Tanksale, P., Imamura, S., Sukhatme, V. P., Lecker, S. H. Statin-induced muscle damage and atrogin-1 induction is the result of a geranylgeranylation defect. PMID:19406843

Carcinogenic damage to deoxyribonucleic acid is induced by near-infrared laser pulses in multiphoton microscopy via combination of two- and three-photon absorption

NASA Astrophysics Data System (ADS)

Nadiarnykh, Oleg; Thomas, Giju; Van Voskuilen, Johan; Sterenborg, Henricus J. C. M.; Gerritsen, Hans C.

2012-11-01

Nonlinear optical imaging modalities (multiphoton excited fluorescence, second and third harmonic generation) applied in vivo are increasingly promising for clinical diagnostics and the monitoring of cancer and other disorders, as they can probe tissue with high diffraction-limited resolution at near-infrared (IR) wavelengths. However, high peak intensity of femtosecond laser pulses required for two-photon processes causes formation of cyclobutane-pyrimidine-dimers (CPDs) in cellular deoxyribonucleic acid (DNA) similar to damage from exposure to solar ultraviolet (UV) light. Inaccurate repair of subsequent mutations increases the risk of carcinogenesis. In this study, we investigate CPD damage that results in Chinese hamster ovary cells in vitro from imaging them with two-photon excited autofluorescence. The CPD levels are quantified by immunofluorescent staining. We further evaluate the extent of CPD damage with respect to varied wavelength, pulse width at focal plane, and pixel dwell time as compared with more pronounced damage from UV sources. While CPD damage has been expected to result from three-photon absorption, our results reveal that CPDs are induced by competing two- and three-photon absorption processes, where the former accesses UVA absorption band. This finding is independently confirmed by nonlinear dependencies of damage on laser power, wavelength, and pulse width.

Dynamic maps of UV damage formation and repair for the human genome

PubMed Central

Hu, Jinchuan; Adebali, Ogun; Adar, Sheera; Sancar, Aziz

2017-01-01

Formation and repair of UV-induced DNA damage in human cells are affected by cellular context. To study factors influencing damage formation and repair genome-wide, we developed a highly sensitive single-nucleotide resolution damage mapping method [high-sensitivity damage sequencing (HS–Damage-seq)]. Damage maps of both cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts [(6-4)PPs] from UV-irradiated cellular and naked DNA revealed that the effect of transcription factor binding on bulky adducts formation varies, depending on the specific transcription factor, damage type, and strand. We also generated time-resolved UV damage maps of both CPDs and (6-4)PPs by HS–Damage-seq and compared them to the complementary repair maps of the human genome obtained by excision repair sequencing to gain insight into factors that affect UV-induced DNA damage and repair and ultimately UV carcinogenesis. The combination of the two methods revealed that, whereas UV-induced damage is virtually uniform throughout the genome, repair is affected by chromatin states, transcription, and transcription factor binding, in a manner that depends on the type of DNA damage. PMID:28607063

Dynamic maps of UV damage formation and repair for the human genome.

PubMed

Hu, Jinchuan; Adebali, Ogun; Adar, Sheera; Sancar, Aziz

2017-06-27

Formation and repair of UV-induced DNA damage in human cells are affected by cellular context. To study factors influencing damage formation and repair genome-wide, we developed a highly sensitive single-nucleotide resolution damage mapping method [high-sensitivity damage sequencing (HS-Damage-seq)]. Damage maps of both cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts [(6-4)PPs] from UV-irradiated cellular and naked DNA revealed that the effect of transcription factor binding on bulky adducts formation varies, depending on the specific transcription factor, damage type, and strand. We also generated time-resolved UV damage maps of both CPDs and (6-4)PPs by HS-Damage-seq and compared them to the complementary repair maps of the human genome obtained by excision repair sequencing to gain insight into factors that affect UV-induced DNA damage and repair and ultimately UV carcinogenesis. The combination of the two methods revealed that, whereas UV-induced damage is virtually uniform throughout the genome, repair is affected by chromatin states, transcription, and transcription factor binding, in a manner that depends on the type of DNA damage.

Prevention of UVB Radiation-induced Epidermal Damage by Expression of Heat Shock Protein 70*

PubMed Central

Matsuda, Minoru; Hoshino, Tatsuya; Yamashita, Yasuhiro; Tanaka, Ken-ichiro; Maji, Daisuke; Sato, Keizo; Adachi, Hiroaki; Sobue, Gen; Ihn, Hironobu; Funasaka, Yoko; Mizushima, Tohru

2010-01-01

Irradiation with UV light, especially UVB, causes epidermal damage via the induction of apoptosis, inflammatory responses, and DNA damage. Various stressors, including UV light, induce heat shock proteins (HSPs) and the induction, particularly that of HSP70, provides cellular resistance to such stressors. The anti-inflammatory activity of HSP70, such as its inhibition of nuclear factor kappa B (NF-κB), was recently revealed. These in vitro results suggest that HSP70 protects against UVB-induced epidermal damage. Here we tested this idea by using transgenic mice expressing HSP70 and cultured keratinocytes. Irradiation of wild-type mice with UVB caused epidermal damage such as induction of apoptosis, which was suppressed in transgenic mice expressing HSP70. UVB-induced apoptosis in cultured keratinocytes was suppressed by overexpression of HSP70. Irradiation of wild-type mice with UVB decreased the cutaneous level of IκB-α (an inhibitor of NF-κB) and increased the infiltration of leukocytes and levels of pro-inflammatory cytokines and chemokines in the epidermis. These inflammatory responses were suppressed in transgenic mice expressing HSP70. In vitro, the overexpression of HSP70 suppressed the expression of pro-inflammatory cytokines and chemokines and increased the level of IκB-α in keratinocytes irradiated with UVB. UVB induced an increase in cutaneous levels of cyclobutane pyrimidine dimers and 8-hydroxy-2′-deoxyguanosine, both of which were suppressed in transgenic mice expressing HSP70. This study provides genetic evidence that HSP70 protects the epidermis from UVB-induced radiation damage. The findings here also suggest that the protective action of HSP70 is mediated by anti-apoptotic, anti-inflammatory, and anti-DNA damage effects. PMID:20018843

Characterization of UVC-induced DNA damage in bloodstains: forensic implications.

PubMed

Hall, Ashley; Ballantyne, Jack

2004-09-01

The ability to detect DNA polymorphisms using molecular genetic techniques has revolutionized the forensic analysis of biological evidence. DNA typing now plays a critical role within the criminal justice system, but one of the limiting factors with the technology is that DNA isolated from biological stains recovered from the crime scene is sometimes so damaged as to be intractable to analysis. Potential remedies for damaged DNA are likely to be dependent upon the precise nature of the DNA damage present in any particular sample but, unfortunately, current knowledge of the biochemical nature, and the extent, of such DNA damage in dried biological stains is rudimentary. As a model for DNA damage assessment in biological stains recovered from crime scenes, we have subjected human bloodstains and naked DNA in the hydrated and dehydrated states to varying doses of UVC radiation. It was possible to damage the DNA sufficiently in a bloodstain to cause a standard autosomal short tandem repeat (STR) profile to be lost. However, a detailed analysis of the process, based upon assays developed to detect bipyrimidine photoproducts (BPPPs), single- and double-strand breaks, and DNA-DNA crosslinks, produced some unexpected findings. Contrary to the situation with living tissues or cells in culture, the predominant UVC-induced damage to DNA in bloodstains appears not to be pyrimidine dimers. Although some evidence for the presence of BPPPs and DNA crosslinks was obtained, the major form of UVC damage causing genetic profile loss appeared to be single-strand breaks. It was not possible, however, to preclude the possibility that a combination of damage types was responsible for the profile loss observed. We demonstrate here that a significant measure of protection against UVC-mediated genetic profile loss in dried biological stain material is afforded by the dehydrated state of the DNA and, to a lesser extent, the DNA cellular milieu.

Oxidative stress-induced protein damage inhibits DNA repair and determines mutation risk and anticancer drug effectiveness

PubMed Central

McAdam, Elizabeth; Brem, Reto; Karran, Peter

2016-01-01

The relationship between sun exposure and non-melanoma skin cancer risk is well established. Solar ultraviolet radiation (UV; wavelengths 280-400 nm) is firmly implicated in skin cancer development. Nucleotide excision repair (NER) protects against cancer by removing potentially mutagenic DNA lesions induced by UVB (280-320 nm). How the 20-fold more abundant UVA (320-400 mn) component of solar UV radiation increases skin cancer risk is not understood. We demonstrate here that the contribution of UVA to the effects of UV radiation on cultured human cells is largely independent of its ability to damage DNA. Instead, the effects of UVA reflect the induction of oxidative stress that causes extensive protein oxidation. Because NER proteins are among those damaged, UVA irradiation inhibits NER and increases the cells’ susceptibility to mutation by UVB. NER inhibition is a common consequence of oxidative stress. Exposure to chemical oxidants, treatment with drugs that deplete cellular antioxidants, and interventions that interfere with glucose metabolism to disrupt the supply of cellular reducing power all inhibit NER. Tumor cells are often in a condition of oxidative stress and one effect of the NER inhibition that results from stress-induced protein oxidation is an increased sensitivity to the anticancer drug cisplatin. Statement of implication: Since NER is both a defence against cancer a significant determinant of cell survival after treatment with anticancer drugs, its attenuation by protein damage under conditions of oxidative-stress has implications for both cancer risk and for the effectiveness of anticancer therapy. PMID:27106867

Drugs of abuse and addiction: A slippery slope toward liver injury.

PubMed

Roy, Dijendra Nath; Goswami, Ritobrata

2016-08-05

Substances of abuse induce alteration in neurobehavioral symptoms, which can lead to simultaneous exacerbation of liver injury. The biochemical changes of liver are significantly observed in the abused group of people using illicit drugs or drugs that are abused. A huge amount of work has been carried out by scientists for validation experiments using animal models to assess hepatotoxicity in cases of drugs of abuse. The risk of hepatotoxicity from these psychostimulants has been determined by different research groups. Hepatotoxicity of these drugs has been recently highlighted and isolated case reports always have been documented in relation to misuse of the drugs. These drugs induce liver toxicity on acute or chronic dose dependent process, which ultimately lead to liver damage, acute fatty infiltration, cholestatic jaundice, liver granulomas, hepatitis, liver cirrhosis etc. Considering the importance of drug-induced hepatotoxicity as a major cause of liver damage, this review emphasizes on various drugs of abuse and addiction which induce hepatotoxicity along with their mechanism of liver damage in clinical aspect as well as in vitro and in vivo approach. However, the mechanisms of drug-induced hepatotoxicity is dependent on reactive metabolite formation via metabolism, modification of covalent bonding between cellular components with drug and its metabolites, reactive oxygen species generation inside and outside of hepatocytes, activation of signal transduction pathways that alter cell death or survival mechanism, and cellular mitochondrial damage, which leads to alteration in ATP generation have been notified here. Moreover, how the cytokines are modulated by these drugs has been mentioned here. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The dual role of autophagy under hypoxia-involvement of interaction between autophagy and apoptosis.

PubMed

Li, Mengmeng; Tan, Jin; Miao, Yuyang; Lei, Ping; Zhang, Qiang

2015-06-01

Hypoxia is one of severe cellular stress and it is well known to be associated with a worse outcome since a lack of oxygen accelerates the induction of apoptosis. Autophagy, an important and evolutionarily conserved mechanism for maintaining cellular homeostasis, is closely related to the apoptosis caused by hypoxia. Generally autophagy blocks the induction of apoptosis and inhibits the activation of apoptosis-associated caspase which could reduce cellular injury. However, in special cases, autophagy or autophagy-relevant proteins may help to induce apoptosis, which could aggravate cell damage under hypoxia condition. In addition, the activation of apoptosis-related proteins-caspase can also degrade autophagy-related proteins, such as Atg3, Atg4, Beclin1 protein, inhibiting autophagy. Although the relationship between autophagy and apoptosis has been known for rather complex for more than a decade, the underlying regulatory mechanisms have not been clearly understood. This short review discusses and summarizes the dual role of autophagy and the interaction and molecular regulatory mechanisms between autophagy and apoptosis under hypoxia.

Enzymatic and cellular responses in relation to body burden of PAHs in bivalve molluscs: a case study with chronic levels of North Sea and Barents Sea dispersed oil.

PubMed

Baussant, T; Bechmann, R K; Taban, I C; Larsen, B K; Tandberg, A H; Bjørnstad, A; Torgrimsen, S; Naevdal, A; Øysaed, K B; Jonsson, G; Sanni, S

2009-12-01

Mytilus edulis and Chlamys islandica were exposed to nominal dispersed crude oil concentrations in the range 0.015-0.25 mg/l for one month. Five biomarkers (enzymatic and cellular responses) were analysed together with bioaccumulation of PAHs at the end of exposure. In both species, PAH tissue residues reflected the exposure concentration measured in the water and lipophilicity determined the bioaccumulation levels. Oil caused biomarker responses in both species but more significant alterations in exposed C. islandica were observed. The relationships between exposure levels and enzymatic responses were apparently complex. The integrated biomarker response related against the exposure levels was U-shaped in both species and no correlation with total PAH body burden was found. For the monitoring of chronic offshore discharges, dose- and time-related events should be evaluated in the selection of biomarkers to apply. From this study, cellular damages appear more fitted than enzymatic responses, transient and more complex to interpret.

Complementary Models of Post-traumatic Osteoarthritis Reveal Cellular Responses to Contact Stress that Damage Articular Cartilage and Present Targets for Intervention

PubMed Central

Martin, James A.; Anderson, Donald D.; Goetz, Jessica E.; Fredericks, Douglas; Pedersen, Douglas R.; Ayati, Bruce P.; Marsh, J. Lawrence; Buckwalter, Joseph A.

2016-01-01

Two categories of joint overloading cause post-traumatic osteoarthritis (PTOA): single acute traumatic loads/impactions and repetitive overloading due to incongruity/instability. We developed and refined three classes of complementary models to define relationships between joint overloading and progressive cartilage loss across the spectrum of acute injuries and chronic joint abnormalities: explant and whole joint models that allow probing of cellular responses to mechanical injury and contact stresses, animal models that enable study of PTOA pathways in living joints and pre-clinical testing of treatments, and patient-specific computational models that define the overloading that causes OA in humans. We coordinated methodologies across models so that results from each informed the others, maximizing the benefit of this complementary approach. We are incorporating results from these investigations into biomathematical models to provide predictions of PTOA risk and guide treatment. Each approach has limitations, but each provides opportunities to elucidate PTOA pathogenesis. Taken together, they help define levels of joint overloading that cause cartilage destruction, show that both forms of overloading can act through the same biologic pathways, and create a framework for initiating clinical interventions that decrease PTOA risk. PMID:27509320

Fatigue failure of osteocyte cellular processes: implications for the repair of bone.

PubMed

Dooley, C; Cafferky, D; Lee, T C; Taylor, D

2014-01-25

The physical effects of fatigue failure caused by cyclic strain are important and for most materials well understood. However, nothing is known about this mode of failure in living cells. We developed a novel method that allowed us to apply controlled levels of cyclic displacement to networks of osteocytes in bone. We showed that under cyclic loading, fatigue failure takes place in the dendritic processes of osteocytes at cyclic strain levels as low as one tenth of the strain needed for instantaneous rupture. The number of cycles to failure was inversely correlated with the strain level. Further experiments demonstrated that these failures were not artefacts of our methods of sample preparation and testing, and that fatigue failure of cell processes also occurs in vivo. This work is significant as it is the first time it has been possible to conduct fatigue testing on cellular material of any kind. Many types of cells experience repetitive loading which may cause failure or damage requiring repair. It is clinically important to determine how cyclic strain affects cells and how they respond in order to gain a deeper understanding of the physiological processes stimulated in this manner. The more we understand about the natural repair process in bone the more targeted the intervention methods may become if disruption of the repair process occurred. Our results will help to understand how the osteocyte cell network is disrupted in the vicinity of matrix damage, a crucial step in bone remodelling.

Changes in metabolites, antioxidant system, and gene expression in Microcystis aeruginosa under sodium chloride stress.

PubMed

Chen, Lei; Mao, Feijian; Kirumba, George Chira; Jiang, Cheng; Manefield, Mike; He, Yiliang

2015-12-01

Microcystis (M.) aeruginosa, one of the most common bloom-forming cyanobacteria, occurs worldwide. The Qingcaosha (QCS) Reservoir is undergoing eutrophication and faces the problem of saltwater intrusion. The aim of this study was to investigate the effects of sudden salinity changes on physiological parameters and related gene transcription in M. aeruginosa under controlled laboratory conditions. The results showed that sodium chloride (50, 200 and 500 mg L(-1) NaCl) inhibited the algal growth and decreased pigment concentrations (chlorophyll a, carotenoid and phycocyanin). Sodium chloride increased both the intracellular and extracellular microcystin contents and elevated the mcyD transcript level in M. aeruginosa. It also increased the malondialdehyde (MDA) content and caused cytomembrane damage. This damage caused the release of intracellular toxins into the culture medium. In addition, NaCl decreased the maximum electron transport rate, increased the levels of reactive oxygen species (ROS) and changed the cellular redox status. Consequently, NaCl inhibited the expression of cpcB, psbA and rbcL. Furthermore, NaCl increased the activities of superoxide dismutases (SOD), catalase (CAT), glutathione reductase (GR), and total glutathione peroxidase (GPx). The transcript levels of sod and reduced glutathione (gsh) were also increased after exposure to NaCl. Our results indicate that a sudden increase in salinity increases the production and excretion of microcystin, changes the cellular redox status, enhances the activities of antioxidant enzymes, inhibits photosynthesis, and affects transcript levels of related genes in M. aeruginosa. Copyright © 2015 Elsevier Inc. All rights reserved.

N-acetyl cysteine reverts the proinflammatory state induced by cigarette smoke extract in lung Calu-3 cells.

PubMed

Valdivieso, Ángel G; Dugour, Andrea V; Sotomayor, Verónica; Clauzure, Mariángeles; Figueroa, Juan M; Santa-Coloma, Tomás A

2018-06-01

Chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) are lethal pulmonary diseases. Cigarette consumption is the main cause for development of COPD, while CF is produced by mutations in the CFTR gene. Although these diseases have a different etiology, both share a CFTR activity impairment and proinflammatory state even under sterile conditions. The aim of this work was to study the extent of the protective effect of the antioxidant N-acetylcysteine (NAC) over the proinflammatory state (IL-6 and IL-8), oxidative stress (reactive oxygen species, ROS), and CFTR levels, caused by Cigarette Smoke Extract (CSE) in Calu-3 airway epithelial cells. CSE treatment (100 µg/ml during 24 h) decreased CFTR mRNA expression and activity, and increased the release of IL-6 and IL-8. The effect on these cytokines was inhibited by N-acetyl cysteine (NAC, 5 mM) or the NF-kB inhibitor, IKK-2 (10 µM). CSE treatment also increased cellular and mitochondrial ROS levels. The cellular ROS levels were normalized to control values by NAC treatment, although significant effects on mitochondrial ROS levels were observed only at short times (5´) and effects on CFTR levels were not observed. In addition, CSE reduced the mitochondrial NADH-cytochrome c oxidoreductase (mCx I-III) activity, an effect that was not reverted by NAC. The reduced CFTR expression and the mitochondrial damage induced by CSE could not be normalized by NAC treatment, evidencing the need for a more specific reagent. In conclusion, CSE causes a sterile proinflammatory state and mitochondrial damage in Calu-3 cells that was partially recovered by NAC treatment. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Enzyme polymorphism, oxygen and injury: a lipidomic analysis of flight-induced oxidative damage in a succinate dehydrogenase d (Sdhd)-polymorphic insect.

PubMed

Pekny, Julianne E; Smith, Philip B; Marden, James H

2018-03-23

When active tissues receive insufficient oxygen to meet metabolic demand, succinate accumulates and has two fundamental effects: it causes ischemia-reperfusion injury while also activating the hypoxia-inducible factor pathway (HIF). The Glanville fritillary butterfly ( Melitaea cinxia ) possesses a balanced polymorphism in Sdhd , shown previously to affect HIF pathway activation and tracheal morphology and used here to experimentally test the hypothesis that variation in succinate dehydrogenase affects oxidative injury . We stimulated butterflies to fly continuously in a respirometer (3 min duration), which typically caused episodes of exhaustion and recovery, suggesting a potential for cellular injury from hypoxia and reoxygenation in flight muscles. Indeed, flight muscle from butterflies flown on consecutive days had lipidome profiles similar to those of rested paraquat-injected butterflies, but distinct from those of rested untreated butterflies. Many butterflies showed a decline in flight metabolic rate (FMR) on day 2, and there was a strong inverse relationship between the ratio of day 2 to day 1 FMR and the abundance of sodiated adducts of phosphatidylcholines and co-enzyme Q (CoQ). This result is consistent with elevation of sodiated lipids caused by disrupted intracellular ion homeostasis in mammalian tissues after hypoxia-reperfusion. Butterflies carrying the Sdhd M allele had a higher abundance of lipid markers of cellular damage, but the association was reversed in field-collected butterflies, where focal individuals typically flew for seconds at a time rather than continuously. These results indicate that Glanville fritillary flight muscles can be injured by episodes of high exertion, but injury severity appears to be determined by an interaction between SDH genotype and behavior (prolonged versus intermittent flight). © 2018. Published by The Company of Biologists Ltd.

Fisetin inhibits cellular proliferation and induces mitochondria-dependent apoptosis in human gastric cancer cells.

PubMed

Sabarwal, Akash; Agarwal, Rajesh; Singh, Rana P

2017-02-01

The anticancer effects of fisetin, a dietary agent, are largely unknown against human gastric cancer. Herein, we investigated the mechanisms of fisetin-induced inhibition of growth and survival of human gastric carcinoma AGS and SNU-1 cells. Fisetin (25-100 μM) caused significant decrease in the levels of G1 phase cyclins and CDKs, and increased the levels of p53 and its S15 phosphorylation in gastric cancer cells. We also observed that growth suppression and death of non-neoplastic human intestinal FHs74int cells were minimally affected by fisetin. Fisetin strongly increased apoptotic cells and showed mitochondrial membrane depolarization in gastric cancer cells. DNA damage was observed as early as 3 h after fisetin treatment which was accompanied with gamma-H2A.X(S139) phosphorylation and cleavage of PARP. Fisetin-induced apoptosis was observed to be independent of p53. DCFDA and MitoSOX analyses showed an increase in mitochondrial ROS generation in time- and dose-dependent fashion. It also increased cellular nitrite and superoxide generation. Pre-treatment with N-acetyl cysteine (NAC) inhibited ROS generation and also caused protection from fisetin-induced DNA damage. The formation of comets were observed in only fisetin treated cells which was blocked by NAC pre-treatment. Further investigation of the source of ROS, using mitochondrial respiratory chain (MRC) complex inhibitors, suggested that fisetin caused ROS generation specifically through complex I. Collectively, these results for the first time demonstrated that fisetin possesses anticancer potential through ROS production most likely via MRC complex I leading to apoptosis in human gastric carcinoma cells. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Humanin G (HNG) protects age-related macular degeneration (AMD) transmitochondrial ARPE-19 cybrids from mitochondrial and cellular damage.

PubMed

Nashine, Sonali; Cohen, Pinchas; Chwa, Marilyn; Lu, Stephanie; Nesburn, Anthony B; Kuppermann, Baruch D; Kenney, M Cristina

2017-07-20

Age-related macular degeneration (AMD) ranks third among the leading causes of visual impairment with a blindness prevalence rate of 8.7%. Despite several treatment regimens, such as anti-angiogenic drugs, laser therapy, and vitamin supplementation, being available for wet AMD, to date there are no FDA-approved therapies for dry AMD. Substantial evidence implicates mitochondrial damage and retinal pigment epithelium (RPE) cell death in the pathogenesis of AMD. However, the effects of AMD mitochondria and Humanin G (HNG), a more potent variant of the mitochondrial-derived peptide (MDP) Humanin, on retinal cell survival have not been elucidated. In this study, we characterized mitochondrial and cellular damage in transmitochondrial cybrid cell lines that contain identical nuclei but possess mitochondria from either AMD or age-matched normal (Older-normal (NL)) subjects. AMD cybrids showed (1) reduced levels of cell viability, lower mtDNA copy numbers, and downregulation of mitochondrial replication/transcription genes and antioxidant enzyme genes; and (2) elevated levels of genes related to apoptosis, autophagy and ER-stress along with increased mtDNA fragmentation and higher susceptibility to amyloid-β-induced toxicity compared to NL cybrids. In AMD cybrids, HNG protected the AMD mitochondria, reduced pro-apoptosis gene and protein levels, upregulated gp130 (a component of the HN receptor complex), and increased the protection against amyloid-β-induced damage. In summary, in cybrids, damaged AMD mitochondria mediate cell death that can be reversed by HNG treatment. Our results also provide evidence of Humanin playing a pivotal role in protecting cells with AMD mitochondria. In the future, it may be possible that AMD patient's blood samples containing damaged mitochondria may be useful as biomarkers for this condition. In conclusion, HNG may be a potential therapeutic target for treatment of dry AMD, a debilitating eye disease that currently has no available treatment. Further studies are needed to establish HNG as a viable mitochondria-targeting therapy for dry AMD.

Important cellular targets for antimicrobial photodynamic therapy.

PubMed

Awad, Mariam M; Tovmasyan, Artak; Craik, James D; Batinic-Haberle, Ines; Benov, Ludmil T

2016-09-01

The persistent problem of antibiotic resistance has created a strong demand for new methods for therapy and disinfection. Photodynamic inactivation (PDI) of microbes has demonstrated promising results for eradication of antibiotic-resistant strains. PDI is based on the use of a photosensitive compound (photosensitizer, PS), which upon illumination with visible light generates reactive species capable of damaging and killing microorganisms. Since photogenerated reactive species are short lived, damage is limited to close proximity of the PS. It is reasonable to expect that the larger the number of damaged targets is and the greater their variety is, the higher the efficiency of PDI is and the lower the chances for development of resistance are. Exact molecular mechanisms and specific targets whose damage is essential for microbial inactivation have not been unequivocally established. Two main cellular components, DNA and plasma membrane, are regarded as the most important PDI targets. Using Zn porphyrin-based PSs and Escherichia coli as a model Gram-negative microorganism, we demonstrate that efficient photoinactivation of bacteria can be achieved without detectable DNA modification. Among the cellular components which are modified early during illumination and constitute key PDI targets are cytosolic enzymes, membrane-bound protein complexes, and the plasma membrane. As a result, membrane barrier function is lost, and energy and reducing equivalent production is disrupted, which in turn compromises cell defense mechanisms, thus augmenting the photoinduced oxidative injury. In conclusion, high PDI antimicrobial effectiveness does not necessarily require impairment of a specific critical cellular component and can be achieved by inducing damage to multiple cellular targets.

Blueberry extracts protect testis from hypobaric hypoxia induced oxidative stress in rats.

PubMed

Zepeda, Andrea; Aguayo, Luis G; Fuentealba, Jorge; Figueroa, Carolina; Acevedo, Alejandro; Salgado, Perla; Calaf, Gloria M; Farías, Jorge

2012-01-01

Exposure to hypobaric hypoxia causes oxidative damage to male rat reproductive function. The aim of this study was to evaluate the protective effect of a blueberry extract (BB-4) in testis of rats exposed to hypobaric hypoxia. Morphometric analysis, cellular DNA fragmentation, glutathione reductase (GR), and superoxide dismutase (SOD) activities were evaluated. Our results showed that supplementation of BB-4 reduced lipid peroxidation, decreased apoptosis, and increased GR and SOD activities in rat testis under hypobaric hypoxia conditions (P < 0.05). Therefore, this study demonstrates that blueberry extract significantly reduced the harmful effects of oxidative stress caused by hypobaric hypoxia in rat testis by affecting glutathione reductase and superoxide dismutase activities.

Chk1 Promotes DNA Damage Response Bypass following Oxidative Stress in a Model of Hydrogen Peroxide-Associated Ulcerative Colitis through JNK Inactivation and Chromatin Binding.

PubMed

Reissig, Kathrin; Silver, Andrew; Hartig, Roland; Schinlauer, Antje; Walluscheck, Diana; Guenther, Thomas; Siedentopf, Sandra; Ross, Jochen; Vo, Diep-Khanh; Roessner, Albert; Poehlmann-Nitsche, Angela

2017-01-01

Dysregulation of c-Jun N -terminal kinase (JNK) activation promoted DNA damage response bypass and tumorigenesis in our model of hydrogen peroxide-associated ulcerative colitis (UC) and in patients with quiescent UC (QUC), UC-related dysplasia, and UC-related carcinoma (UC-CRC), thereby adapting to oxidative stress. In the UC model, we have observed features of oncogenic transformation: increased proliferation, undetected DNA damage, and apoptosis resistance. Here, we show that Chk1 was downregulated but activated in the acute and quiescent chronic phases. In both phases, Chk1 was linked to DNA damage response bypass by suppressing JNK activation following oxidative stress, promoting cell cycle progression despite DNA damage. Simultaneously, activated Chk1 was bound to chromatin. This triggered histone acetylation and the binding of histone acetyltransferases and transcription factors to chromatin. Thus, chromatin-immobilized activated Chk1 executed a dual function by suppressing DNA damage response and simultaneously inducing chromatin modulation. This caused undetected DNA damage and increased cellular proliferation through failure to transmit the appropriate DNA damage signal. Findings in vitro were corroborated by chromatin accumulation of activated Chk1, Ac-H3, Ac-H4, and c-Jun in active UC (AUC) in vivo. Targeting chromatin-bound Chk1, GCN5, PCAF, and p300/CBP could be a novel therapeutic strategy to prevent UC-related tumor progression.

Perinatal Asphyxia and Brain Development: Mitochondrial Damage Without Anatomical or Cellular Losses.

PubMed

Lima, Jean Pierre Mendes; Rayêe, Danielle; Silva-Rodrigues, Thaia; Pereira, Paula Ribeiro Paes; Mendonca, Ana Paula Miranda; Rodrigues-Ferreira, Clara; Szczupak, Diego; Fonseca, Anna; Oliveira, Marcus F; Lima, Flavia Regina Souza; Lent, Roberto; Galina, Antonio; Uziel, Daniela

2018-03-26

Perinatal asphyxia remains a significant cause of neonatal mortality and is associated with long-term neurodegenerative disorders. In the present study, we evaluated cellular and subcellular damages to brain development in a model of mild perinatal asphyxia. Survival rate in the experimental group was 67%. One hour after the insult, intraperitoneally injected Evans blue could be detected in the fetuses' brains, indicating disruption of the blood-brain barrier. Although brain mass and absolute cell numbers (neurons and non-neurons) were not reduced after perinatal asphyxia immediately and in late brain development, subcellular alterations were detected. Cortical oxygen consumption increased immediately after asphyxia, and remained high up to 7 days, returning to normal levels after 14 days. We observed an increased resistance to mitochondrial membrane permeability transition, and calcium buffering capacity in asphyxiated animals from birth to 14 days after the insult. In contrast to ex vivo data, mitochondrial oxygen consumption in primary cell cultures of neurons and astrocytes was not altered after 1% hypoxia. Taken together, our results demonstrate that although newborns were viable and apparently healthy, brain development is subcellularly altered by perinatal asphyxia. Our findings place the neonate brain mitochondria as a potential target for therapeutic protective interventions.

Tip60 degradation by adenovirus relieves transcriptional repression of viral transcriptional activator EIA.

PubMed

Gupta, A; Jha, S; Engel, D A; Ornelles, D A; Dutta, A

2013-10-17

Adenoviruses are linear double-stranded DNA viruses that infect human and rodent cell lines, occasionally transform them and cause tumors in animal models. The host cell challenges the virus in multifaceted ways to restrain viral gene expression and DNA replication, and sometimes even eliminates the infected cells by programmed cell death. To combat these challenges, adenoviruses abrogate the cellular DNA damage response pathway. Tip60 is a lysine acetyltransferase that acetylates histones and other proteins to regulate gene expression, DNA damage response, apoptosis and cell cycle regulation. Tip60 is a bona fide tumor suppressor as mice that are haploid for Tip60 are predisposed to tumors. We have discovered that Tip60 is degraded by adenovirus oncoproteins EIB55K and E4orf6 by a proteasome-mediated pathway. Tip60 binds to the immediate early adenovirus promoter and suppresses adenovirus EIA gene expression, which is a master regulator of adenovirus transcription, at least partly through retention of the virally encoded repressor pVII on this promoter. Thus, degradation of Tip60 by the adenoviral early proteins is important for efficient viral early gene transcription and for changes in expression of cellular genes.

Adverse Health Effects of Thirdhand Smoke: From Cell to Animal Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hang, Bo; Wang, Pin; Zhao, Yue

The newly identified smoke hazard, thirdhand smoke (THS), has gained public attention in recent years but its health impact and biological effects are largely unknown. THS may be defined by “the four Rs”: tobacco chemicals that remain, react, re-emit, and/or are resuspended long after active smoking has ceased. This review summarizes recent research progress in the effects of THS on genotoxicity, metabolism and early life development using cellular and animal models. We first reported that THS generated in laboratory systems caused significant DNA damage in human cell lines. Our finding that THS significantly induces oxidative base lesions has been confirmedmore » in skin wounds of mice models exposed to THS. THS also induced metabolomic changes in human reproductive cell lines. Furthermore, we demonstrated that early exposure to THS not only negatively impacts body weight in both male and female mice, but also induces persistent changes to immunological parameters in peripheral blood in these mice. These results indicate that THS is genotoxic at realistic experimental doses and that there may be a window of susceptibility for some forms of cellular damage induced by THS.« less

Carcinogenicity of chromium and chemoprevention: a brief update

PubMed Central

Gu, Yuanliang; Song, Xin; Zhao, Jinshun

2017-01-01

Chromium has two main valence states: hexavalent chromium (Cr[VI]) and trivalent chromium (Cr[III]). Cr(VI), a well-established human carcinogen, can enter cells by way of a sulfate/phosphate anion-transport system, and then be reduced to lower-valence intermediates consisting of pentavalent chromium (Cr[V]), tetravalent chromium (Cr[IV]) or Cr(III) via cellular reductants. These intermediates may directly or indirectly result in DNA damage or DNA–protein cross-links. Although Cr(III) complexes cannot pass easily through cell membranes, they have the ability to accumulate around cells to induce cell-surface morphological alteration and result in cell-membrane lipid injuries via disruption of cellular functions and integrity, and finally to cause DNA damage. In recent years, more research, including in vitro, in vivo, and epidemiological studies, has been conducted to evaluate the genotoxicity/carcinogenicity induced by Cr(VI) and/or Cr(III) compounds. At the same time, various therapeutic agents, especially antioxidants, have been explored through in vitro and in vivo studies for preventing chromium-induced genotoxicity/carcinogenesis. This review aims to provide a brief update on the carcinogenicity of Cr(VI) and Cr(III) and chemoprevention with different antioxidants. PMID:28860815

Click chemistry for the conservation of cellular structures and fluorescent proteins: ClickOx.

PubMed

Löschberger, Anna; Niehörster, Thomas; Sauer, Markus

2014-05-01

Reactive oxygen species (ROS), including hydrogen peroxide, are known to cause structural damage not only in living, but also in fixed, cells. Copper-catalyzed azide-alkyne cycloaddition (click chemistry) is known to produce ROS. Therefore, fluorescence imaging of cellular structures, such as the actin cytoskeleton, remains challenging when combined with click chemistry protocols. In addition, the production of ROS substantially weakens the fluorescence signal of fluorescent proteins. This led us to develop ClickOx, which is a new click chemistry protocol for improved conservation of the actin structure and better conservation of the fluorescence signal of green fluorescent protein (GFP)-fusion proteins. Herein we demonstrate that efficient oxygen removal by addition of an enzymatic oxygen scavenger system (ClickOx) considerably reduces ROS-associated damage during labeling of nascent DNA with ATTO 488 azide by Cu(I)-catalyzed click chemistry. Standard confocal and super-resolution fluorescence images of phalloidin-labeled actin filaments and GFP/yellow fluorescent protein-labeled cells verify the conservation of the cytoskeleton microstructure and fluorescence intensity, respectively. Thus, ClickOx can be used advantageously for structure preservation in conventional and most notably in super-resolution microscopy methods. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adverse Health Effects of Thirdhand Smoke: From Cell to Animal Models

DOE PAGES

Hang, Bo; Wang, Pin; Zhao, Yue; ...

2017-04-28

The newly identified smoke hazard, thirdhand smoke (THS), has gained public attention in recent years but its health impact and biological effects are largely unknown. THS may be defined by “the four Rs”: tobacco chemicals that remain, react, re-emit, and/or are resuspended long after active smoking has ceased. This review summarizes recent research progress in the effects of THS on genotoxicity, metabolism and early life development using cellular and animal models. We first reported that THS generated in laboratory systems caused significant DNA damage in human cell lines. Our finding that THS significantly induces oxidative base lesions has been confirmedmore » in skin wounds of mice models exposed to THS. THS also induced metabolomic changes in human reproductive cell lines. Furthermore, we demonstrated that early exposure to THS not only negatively impacts body weight in both male and female mice, but also induces persistent changes to immunological parameters in peripheral blood in these mice. These results indicate that THS is genotoxic at realistic experimental doses and that there may be a window of susceptibility for some forms of cellular damage induced by THS.« less

Protective Effect of Edaravone Against Aβ25-35-Induced Mitochondrial Oxidative Damage in SH-SY5Y Cells.

PubMed

Zhang, G-L; Zhang, L; Guo, Y-Y; Ma, Z-L; Wang, H-Y; Li, T; Liu, J; Du, Y; Yao, L; Li, T-T; Du, J-M

2017-05-20

Amyloid-β (Aβ)-induced oxidative stress plays an important role in the pathogenesis of Alzheimer's disease (AD). Recent studies show that Aβ accumulation may lead to mitochondrial oxidative damage. In the present study, we investigated the protective effect of edaravone on mitochondrial damage in SH-SY5Y cells treated with Aβ25-35. SH-SY5Y cells were pre-treated with 20, 40 or 80 μM edaravone before treatment with 25 μM Aβ25-35. After 24h cell culture, cellular apoptosis, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), ATP levels and mitochondrial morphology were evaluated. SH-SY5Y cells exposed to Aβ25-35 had high levels of apoptosis and ROS; loss of ΔΨm, decreased ATP levels and presence of mitochondrial swelling. However, these effects were significantly inhibited by edaravone pre-treatment. These results indicate that edaravone prevents mitochondria oxidative damage caused by Aβ in SH-SY5Y cells, which suggests that it may have potential clinical application in AD therapy.

DNA Excision Repair at Telomeres

PubMed Central

Jia, Pingping; Her, Chengtao; Chai, Weihang

2015-01-01

DNA damage is caused by either endogenous cellular metabolic processes such as hydrolysis, oxidation, alkylation, and DNA base mismatches, or exogenous sources including ultraviolet (UV) light, ionizing radiation, and chemical agents. Damaged DNA that is not properly repaired can lead to genomic instability, driving tumorigenesis. To protect genomic stability, mammalian cells have evolved highly conserved DNA repair mechanisms to remove and repair DNA lesions. Telomeres are composed of long tandem TTAGGG repeats located at the ends of chromosomes. Maintenance of functional telomeres is critical for preventing genome instability. The telomeric sequence possesses unique features that predispose telomeres to a variety of DNA damage induced by environmental genotoxins. This review briefly describes the relevance of excision repair pathways in telomere maintenance, with the focus on base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). By summarizing current knowledge on excision repair of telomere damage and outlining many unanswered questions, it is our hope to stimulate further interest in a better understanding of excision repair processes at telomeres and in how these processes contribute to telomere maintenance. PMID:26422132

Postradiation atrophy of mature bone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erguen, H.; Howland, W.J.

1980-01-01

The growing number of oncological patients subjected to radiotherapy require the diagnostic radiologist to be aware of expected bone changes following irradiation and the differentiation of this entity from metastasis. The primary event of radiation damage to bone is atrophy and true necrosis of bone is uncommon. The postradiation atrophic changes of bone are the result of combined cellular and vascular damage, the former being more important. The damage to the osteoblast resulting in decreased matrix production is apparently the primary histopathologic event. Radiation damaged bone is susceptible to superimposed complications of fracture, infection, necrosis, and sarcoma. The primary radiographicmore » evidence of atrophy, localized osteopenia, is late in appearing, mainly because of the relative insensitivity of radiographs in detecting demineralization. Contrary to former views, the mature bone is quite radiosensitive and reacts quickly to even small doses of radiation. In vivo midrodensitometric analysis and radionuclide bone and bone marrow scans can reveal early changes following irradiation. The differentiation of postirradiation atrophy and metastasis may be difficult. Biopsy should be the last resort because of the possibility of causing true necrosis in atrophic bone by trauma and infection.« less

Postradiation atrophy of mature bone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ergun, H.; Howland, W.J.

1980-01-01

The growing number of oncological patients subjected to radiotherapy require the diagnostic radiologist to be aware of expected bone changes following irradiation and the differentiation of this entity from metastasis. The primary event of radiation damage to bone is atrophy and true necrosis of bone is uncommon. The postradiation atrophic changes of bone are the result of combined cellular and vascular damage, the former being more important. The damage to the osteoblast resulting in decreased matrix production is apparently the primary histopathologic event. Radiation damaged bone is susceptible to superimposed complications of fracture, infection, necrosis, and sarcoma. The primary radiographicmore » evidence of atrophy, localized osteopenia, is late in appearing, mainly because of the relative insensitivity of radiographs in detecing demineralization. Contrary to former views, the mature bone is quite radiosensitive and reacts quickly to even small doses of radiation. In vivo midrodensitometric analysis and radionuclide bone and bone marrow scans can reveal early changes following irradiation. The differentiation of postirradiation atrophy and metastasis may be difficult. Biopsy should be the last resort because of the possibility of causing true necrosis in atrophic bone by trauma and infection.« less

[The correlations between aging of the human body, oxidative stress and reduced efficiency of repair systems].

PubMed

Michalak, Aleksandra; Krzeszowiak, Jakub; Markiewicz-Górka, Iwona

2014-12-15

The article presents an current knowledge overview about the importance of oxidative stress and reduced efficiency of repair processes during the aging process of the human body. Oxidative damage to cellular macromolecules (proteins, lipids, nucleic acids), are formed under the influence of reactive oxygen species (ROS). They are the part of important mechanism which is responsible for the process of aging and the development of many diseases. The most important effects result from DNA damage, due to the mutations formation, which can lead to the development of tumors. However, a well-functioning repair systems (i.a. homologous recombination) remove the damage and prevent harmful changes in the cells. Lipid peroxidation products also cause oxidative modification of nucleic acids (and proteins). Proteins and fats also have repair systems, but much simpler than those responsible for the repair of nucleic acids. Unfortunately, with increasing age, they are more weakened, which contributes to increase numbers of cell damage, and consequently development of diseases specific to old age: cancer, neurodegenerative diseases or atherosclerosis.

Red light improves spermatozoa motility and does not induce oxidative DNA damage

NASA Astrophysics Data System (ADS)

Preece, Daryl; Chow, Kay W.; Gomez-Godinez, Veronica; Gustafson, Kyle; Esener, Selin; Ravida, Nicole; Durrant, Barbara; Berns, Michael W.

2017-04-01

The ability to successfully fertilize ova relies upon the swimming ability of spermatozoa. Both in humans and in animals, sperm motility has been used as a metric for the viability of semen samples. Recently, several studies have examined the efficacy of low dosage red light exposure for cellular repair and increasing sperm motility. Of prime importance to the practical application of this technique is the absence of DNA damage caused by radiation exposure. In this study, we examine the effect of 633 nm coherent, red laser light on sperm motility using a novel wavelet-based algorithm that allows for direct measurement of curvilinear velocity under red light illumination. This new algorithm gives results comparable to the standard computer-assisted sperm analysis (CASA) system. We then assess the safety of red light treatment of sperm by analyzing, (1) the levels of double-strand breaks in the DNA, and (2) oxidative damage in the sperm DNA. The results demonstrate that for the parameters used there are insignificant differences in oxidative DNA damage as a result of irradiation.

Candida parapsilosis Protects Premature Intestinal Epithelial Cells from Invasion and Damage by Candida albicans

PubMed Central

Gonia, Sara; Archambault, Linda; Shevik, Margaret; Altendahl, Marie; Fellows, Emily; Bliss, Joseph M.; Wheeler, Robert T.; Gale, Cheryl A.

2017-01-01

Candida is a leading cause of late-onset sepsis in premature infants and is thought to invade the host via immature or damaged epithelial barriers. We previously showed that the hyphal form of Candida albicans invades and causes damage to premature intestinal epithelial cells (pIECs), whereas the non-hyphal Candida parapsilosis, also a fungal pathogen of neonates, has less invasion and damage abilities. In this study, we investigated the potential for C. parapsilosis to modulate pathogenic interactions of C. albicans with the premature intestine. While a mixed infection with two fungal pathogens may be expected to result in additive or synergistic damage to pIECs, we instead found that C. parapsilosis was able to protect pIECs from invasion and damage by C. albicans. C. albicans-induced pIEC damage was reduced to a similar extent by multiple different C. parapsilosis strains, but strains differed in their ability to inhibit C. albicans invasion of pIECs, with the inhibitory activity correlating with their adhesiveness for C. albicans and epithelial cells. C. parapsilosis cell-free culture fractions were also able to significantly reduce C. albicans adhesion and damage to pIECs. Furthermore, coadministration of C. parapsilosis cell-free fractions with C. albicans was associated with decreased infection and mortality in zebrafish. These results indicate that C. parapsilosis is able to reduce invasion, damage, and virulence functions of C. albicans. Additionally, the results with cellular and cell-free fractions of yeast cultures suggest that inhibition of pathogenic interactions between C. albicans and host cells by C. parapsilosis occurs via secreted molecules as well as by physical contact with the C. parapsilosis cell surface. We propose that non-invasive commensals can be used to inhibit virulence features of pathogens and deserve further study as a non-pharmacological strategy to protect the fragile epithelial barriers of premature infants. PMID:28382297

Photothermal and photoacoustic processes of laser activated nano-thermolysis of cells

NASA Astrophysics Data System (ADS)

Lapotko, Dmitri; Lukianova, Ekaterina; Mitskevich, Pavel; Smolnikova, Victoria; Potapnev, Michail; Konopleva, Marina; Andreeff, Michael; Oraevsky, Alexander

2007-02-01

Laser Activated Nano-Thermolysis was recently proposed for selective damage of individual target (cancer) cells by pulsed laser induced microbubbles around superheated clusters of optically absorbing nanoparticles (NP). One of the clinical applications of this technology is the elimination of residual tumor cells from human blood and bone marrow. Clinical standards for the safety and efficacy of such procedure require the development and verification of highly selective and controllable mechanisms of cell killing. Our previous experiments showed that laser-induced microbubble is the main damaging factor in the case cell irradiation by short laser pulses above the threshold. Our current aim was to study the cell damage mechanisms and analyze selectivity and efficacy of cell damage as a function of NP parameters, NP-cell interaction conditions, and conditions of bubble generation around NP and NP clusters in cells. Generation of laser-induced bubbles around gold NP with diameters 10-250 nm was studied in Acute Myeloblast Leukemia (AML) cultures, normal stem and model K562 human cells. Short laser pulses (10 ns, 532 nm) were applied to those cells in vitro and the processes in cells were investigated with photothermal, fluorescent and atomic force microscopies and also with fluorescence flow cytometry. We have found that the best selectivity of cell damage is achieved by (1) forming large clusters of optically absorbing NP in target cells and (2) irradiating the cells with single laser pulses with the lowest fluence that can generate microbubble only around large clusters but not around single NP. Laser microbubbles with the lifetime from 20 ns to 2000 ns generated in individual cells caused damage and lysis of the cellular membrane and consequently cell death. Laser microbubbles did not damage normal cells around the damaged target (tumor) cell. Laser irradiation with equal fluence did not cause any damage of cells without accumulated NP clusters.

Analyzing structure-function relationships of artificial and cancer-associated PARP1 variants by reconstituting TALEN-generated HeLa PARP1 knock-out cells.

PubMed

Rank, Lisa; Veith, Sebastian; Gwosch, Eva C; Demgenski, Janine; Ganz, Magdalena; Jongmans, Marjolijn C; Vogel, Christopher; Fischbach, Arthur; Buerger, Stefanie; Fischer, Jan M F; Zubel, Tabea; Stier, Anna; Renner, Christina; Schmalz, Michael; Beneke, Sascha; Groettrup, Marcus; Kuiper, Roland P; Bürkle, Alexander; Ferrando-May, Elisa; Mangerich, Aswin

2016-12-01

Genotoxic stress activates PARP1, resulting in the post-translational modification of proteins with poly(ADP-ribose) (PAR). We genetically deleted PARP1 in one of the most widely used human cell systems, i.e. HeLa cells, via TALEN-mediated gene targeting. After comprehensive characterization of these cells during genotoxic stress, we analyzed structure-function relationships of PARP1 by reconstituting PARP1 KO cells with a series of PARP1 variants. Firstly, we verified that the PARP1\\E988K mutant exhibits mono-ADP-ribosylation activity and we demonstrate that the PARP1\\L713F mutant is constitutively active in cells. Secondly, both mutants exhibit distinct recruitment kinetics to sites of laser-induced DNA damage, which can potentially be attributed to non-covalent PARP1-PAR interaction via several PAR binding motifs. Thirdly, both mutants had distinct functional consequences in cellular patho-physiology, i.e. PARP1\\L713F expression triggered apoptosis, whereas PARP1\\E988K reconstitution caused a DNA-damage-induced G2 arrest. Importantly, both effects could be rescued by PARP inhibitor treatment, indicating distinct cellular consequences of constitutive PARylation and mono(ADP-ribosyl)ation. Finally, we demonstrate that the cancer-associated PARP1 SNP variant (V762A) as well as a newly identified inherited PARP1 mutation (F304L\\V762A) present in a patient with pediatric colorectal carcinoma exhibit altered biochemical and cellular properties, thereby potentially supporting human carcinogenesis. Together, we establish a novel cellular model for PARylation research, by revealing strong structure-function relationships of natural and artificial PARP1 variants. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Analyzing structure–function relationships of artificial and cancer-associated PARP1 variants by reconstituting TALEN-generated HeLa PARP1 knock-out cells

PubMed Central

Rank, Lisa; Veith, Sebastian; Gwosch, Eva C.; Demgenski, Janine; Ganz, Magdalena; Jongmans, Marjolijn C.; Vogel, Christopher; Fischbach, Arthur; Buerger, Stefanie; Fischer, Jan M.F.; Zubel, Tabea; Stier, Anna; Renner, Christina; Schmalz, Michael; Beneke, Sascha; Groettrup, Marcus; Kuiper, Roland P.; Bürkle, Alexander; Ferrando-May, Elisa; Mangerich, Aswin

2016-01-01

Genotoxic stress activates PARP1, resulting in the post-translational modification of proteins with poly(ADP-ribose) (PAR). We genetically deleted PARP1 in one of the most widely used human cell systems, i.e. HeLa cells, via TALEN-mediated gene targeting. After comprehensive characterization of these cells during genotoxic stress, we analyzed structure–function relationships of PARP1 by reconstituting PARP1 KO cells with a series of PARP1 variants. Firstly, we verified that the PARP1\\E988K mutant exhibits mono-ADP-ribosylation activity and we demonstrate that the PARP1\\L713F mutant is constitutively active in cells. Secondly, both mutants exhibit distinct recruitment kinetics to sites of laser-induced DNA damage, which can potentially be attributed to non-covalent PARP1–PAR interaction via several PAR binding motifs. Thirdly, both mutants had distinct functional consequences in cellular patho-physiology, i.e. PARP1\\L713F expression triggered apoptosis, whereas PARP1\\E988K reconstitution caused a DNA-damage-induced G2 arrest. Importantly, both effects could be rescued by PARP inhibitor treatment, indicating distinct cellular consequences of constitutive PARylation and mono(ADP-ribosyl)ation. Finally, we demonstrate that the cancer-associated PARP1 SNP variant (V762A) as well as a newly identified inherited PARP1 mutation (F304L\\V762A) present in a patient with pediatric colorectal carcinoma exhibit altered biochemical and cellular properties, thereby potentially supporting human carcinogenesis. Together, we establish a novel cellular model for PARylation research, by revealing strong structure–function relationships of natural and artificial PARP1 variants. PMID:27694308

Oxidative Damage and Cellular Defense Mechanisms in Sea Urchin Models of Aging

PubMed Central

Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

2013-01-01

The free radical or oxidative stress theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging due to the existence of species with tremendously different natural life spans including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate lifespan. Levels of protein carbonyls and 4-hydroxynonenal (HNE) measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age-pigment lipofuscin measured in muscle, nerve and esophagus, increased with age however it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species, however further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. PMID:23707327

Oxidative damage and cellular defense mechanisms in sea urchin models of aging.

PubMed

Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

2013-10-01

The free radical, or oxidative stress, theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging because of the existence of species with tremendously different natural life spans, including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity, and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus, and Strongylocentrotus purpuratus, which has an intermediate life span. Levels of protein carbonyls and 4-hydroxynonenal measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2'-deoxyguanosine measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age pigment lipofuscin, measured in muscle, nerve, and esophagus, increased with age; however, it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species; however, further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age, and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. Copyright © 2013 Elsevier Inc. All rights reserved.

Cellular response to low dose radiation: Role of phosphatidylinositol-3 kinase like kinases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balajee, A.S.; Meador, J.A.; Su, Y.

It is increasingly realized that human exposure either to an acute low dose or multiple chronic low doses of low LET radiation has the potential to cause different types of cancer. Therefore, the central theme of research for DOE and NASA is focused on understanding the molecular mechanisms and pathways responsible for the cellular response to low dose radiation which would not only improve the accuracy of estimating health risks but also help in the development of predictive assays for low dose radiation risks associated with tissue degeneration and cancer. The working hypothesis for this proposal is that the cellularmore » mechanisms in terms of DNA damage signaling, repair and cell cycle checkpoint regulation are different for low and high doses of low LET radiation and that the mode of action of phosphatidylinositol-3 kinase like kinases (PIKK: ATM, ATR and DNA-PK) determines the dose dependent cellular responses. The hypothesis will be tested at two levels: (I) Evaluation of the role of ATM, ATR and DNA-PK in cellular response to low and high doses of low LET radiation in simple in vitro human cell systems and (II) Determination of radiation responses in complex cell microenvironments such as human EpiDerm tissue constructs. Cellular responses to low and high doses of low LET radiation will be assessed from the view points of DNA damage signaling, DNA double strand break repair and cell cycle checkpoint regulation by analyzing the activities (i.e. post-translational modifications and kinetics of protein-protein interactions) of the key target proteins for PI-3 kinase like kinases both at the intra-cellular and molecular levels. The proteins chosen for this proposal are placed under three categories: (I) sensors/initiators include ATM ser1981, ATR, 53BP1, gamma-H2AX, MDC1, MRE11, Rad50 and Nbs1; (II) signal transducers include Chk1, Chk2, FANCD2 and SMC1; and (III) effectors include p53, CDC25A and CDC25C. The primary goal of this proposal is to elucidate the differences in cellular defense mechanisms between low and high doses of low LET radiation and to define the radiation doses where the cellular DNA damage signaling and repair mechanisms tend to shift. This information is critically important to address and advance some of the low dose research program objectives of DOE. The results of this proposed study will lead to a better understanding of the mechanisms for the cellular responses to low and high doses of low LET radiation. Further, systematic analysis of the role of PIKK signaling pathways as a function of radiation dose in tissue microenvironment will provide useful mechanistic information for improving the accuracy of radiation risk assessment for low doses. Knowledge of radiation responses in tissue microenvironment is important for the accurate prediction of ionizing radiation risks associated with cancer and tissue degeneration in humans.« less

Hepatitis B virus and hepatocellular carcinoma

PubMed Central

Arbuthnot, Patrick; Kew, Michael

2001-01-01

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC. PMID:11454100

Reliable Cellular Automata with Self-Organization

NASA Astrophysics Data System (ADS)

Gács, Peter

2001-04-01

In a probabilistic cellular automaton in which all local transitions have positive probability, the problem of keeping a bit of information indefinitely is nontrivial, even in an infinite automaton. Still, there is a solution in 2 dimensions, and this solution can be used to construct a simple 3-dimensional discrete-time universal fault-tolerant cellular automaton. This technique does not help much to solve the following problems: remembering a bit of information in 1 dimension; computing in dimensions lower than 3; computing in any dimension with non-synchronized transitions. Our more complex technique organizes the cells in blocks that perform a reliable simulation of a second (generalized) cellular automaton. The cells of the latter automaton are also organized in blocks, simulating even more reliably a third automaton, etc. Since all this (a possibly infinite hierarchy) is organized in "software," it must be under repair all the time from damage caused by errors. A large part of the problem is essentially self-stabilization recovering from a mess of arbitrary size and content. The present paper constructs an asynchronous one-dimensional fault-tolerant cellular automaton, with the further feature of "self-organization." The latter means that unless a large amount of input information must be given, the initial configuration can be chosen homogeneous.

Dissecting the Molecular Mechanism of Ionizing Radiation-Induced Tissue Damage in the Feather Follicle

PubMed Central

Chen, Xi; Liao, Chunyan; Chu, Qiqi; Zhou, Guixuan; Lin, Xiang; Li, Xiaobo; Lu, Haijie; Xu, Benhua; Yue, Zhicao

2014-01-01

Ionizing radiation (IR) is a common therapeutic agent in cancer therapy. It damages normal tissue and causes side effects including dermatitis and mucositis. Here we use the feather follicle as a model to investigate the mechanism of IR-induced tissue damage, because any perturbation of feather growth will be clearly recorded in its regular yet complex morphology. We find that IR induces defects in feather formation in a dose-dependent manner. No abnormality was observed at 5 Gy. A transient, reversible perturbation of feather growth was induced at 10 Gy, leading to defects in the feather structure. This perturbation became irreversible at 20 Gy. Molecular and cellular analysis revealed P53 activation, DNA damage and repair, cell cycle arrest and apoptosis in the pathobiology. IR also induces patterning defects in feather formation, with disrupted branching morphogenesis. This perturbation is mediated by cytokine production and Stat1 activation, as manipulation of cytokine levels or ectopic Stat1 over-expression also led to irregular feather branching. Furthermore, AG-490, a chemical inhibitor of Stat1 signaling, can partially rescue IR-induced tissue damage. Our results suggest that the feather follicle could serve as a useful model to address the in vivo impact of the many mechanisms of IR-induced tissue damage. PMID:24586618

ATM directs DNA damage responses and proteostasis via genetically separable pathways.

PubMed

Lee, Ji-Hoon; Mand, Michael R; Kao, Chung-Hsuan; Zhou, Yi; Ryu, Seung W; Richards, Alicia L; Coon, Joshua J; Paull, Tanya T

2018-01-09

The protein kinase ATM is a master regulator of the DNA damage response but also responds directly to oxidative stress. Loss of ATM causes ataxia telangiectasia, a neurodegenerative disorder with pleiotropic symptoms that include cerebellar dysfunction, cancer, diabetes, and premature aging. We genetically separated the activation of ATM by DNA damage from that by oxidative stress using separation-of-function mutations. We found that deficient activation of ATM by the Mre11-Rad50-Nbs1 complex and DNA double-strand breaks resulted in loss of cell viability, checkpoint activation, and DNA end resection in response to DNA damage. In contrast, loss of oxidative activation of ATM had minimal effects on DNA damage-related outcomes but blocked ATM-mediated initiation of checkpoint responses after oxidative stress and resulted in deficiencies in mitochondrial function and autophagy. In addition, expression of a variant ATM incapable of activation by oxidative stress resulted in widespread protein aggregation. These results indicate a direct relationship between the mechanism of ATM activation and its effects on cellular metabolism and DNA damage responses in human cells and implicate ATM in the control of protein homeostasis. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Age-Related Macular Degeneration: New Paradigms for Treatment and Management of AMD.

PubMed

Hernández-Zimbrón, Luis Fernando; Zamora-Alvarado, Ruben; Ochoa-De la Paz, Lenin; Velez-Montoya, Raul; Zenteno, Edgar; Gulias-Cañizo, Rosario; Quiroz-Mercado, Hugo; Gonzalez-Salinas, Roberto

2018-01-01

Age-related macular degeneration (AMD) is a well-characterized and extensively studied disease. It is currently considered the leading cause of visual disability among patients over 60 years. The hallmark of early AMD is the formation of drusen, pigmentary changes at the macula, and mild to moderate vision loss. There are two forms of AMD: the "dry" and the "wet" form that is less frequent but is responsible for 90% of acute blindness due to AMD. Risk factors have been associated with AMD progression, and they are taking relevance to understand how AMD develops: (1) advanced age and the exposition to environmental factors inducing high levels of oxidative stress damaging the macula and (2) this damage, which causes inflammation inducing a vicious cycle, altogether causing central vision loss. There is neither a cure nor treatment to prevent AMD. However, there are some treatments available for the wet form of AMD. This article will review some molecular and cellular mechanisms associated with the onset of AMD focusing on feasible treatments for each related factor in the development of this pathology such as vascular endothelial growth factor, oxidative stress, failure of the clearance of proteins and organelles, and glial cell dysfunction in AMD.

Impact of Air Pollutants on Oxidative Stress in Common Autophagy-Mediated Aging Diseases

PubMed Central

Numan, Mohamed Saber; Brown, Jacques P.; Michou, Laëtitia

2015-01-01

Atmospheric pollution-induced cellular oxidative stress is probably one of the pathogenic mechanisms involved in most of the common autophagy-mediated aging diseases, including neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s, disease, as well as Paget’s disease of bone with or without frontotemporal dementia and inclusion body myopathy. Oxidative stress has serious damaging effects on the cellular contents: DNA, RNA, cellular proteins, and cellular organelles. Autophagy has a pivotal role in recycling these damaged non-functional organelles and misfolded or unfolded proteins. In this paper, we highlight, through a narrative review of the literature, that when autophagy processes are impaired during aging, in presence of cumulative air pollution-induced cellular oxidative stress and due to a direct effect on air pollutant, autophagy-mediated aging diseases may occur. PMID:25690002

Calpain-mediated breakdown of cytoskeletal proteins contributes to cholecystokinin-induced damage of rat pancreatic acini.

PubMed

Weber, Heike; Hühns, Saskia; Lüthen, Frank; Jonas, Ludwig

2009-08-01

The cytosolic cysteine protease calpain is implicated in a multitude of cellular functions but also plays a role in cell damage. Our previous results suggest that an activation of calpain accompanied by a decrease in its endogenous inhibitor calpastatin may contribute to pancreatic damage during cerulein-induced acute pancreatitis. The present study aimed at the time course of secretagogue-induced calpain activation and cellular substrates of the protease. Isolated rat pancreatic acini were incubated with a supramaximal concentration of cholecystokinin (0.1 microM CCK) for 30 min in the presence or absence of the calpain inhibitor Z-Val-Phe methyl ester (100 microM ZVP). The activation of calpain and the expression of calpastatin and the actin cytoskeleton-associated proteins alphaII-spectrin, E-cadherin and vinculin were studied by immunoblotting. The cell damage was assessed by lactate dehydrogenase release and ultrastructural analysis including fluorescence-labelled actin filaments. Immediately after administration, CCK led to activation of both calpain isoforms, mu- and m-calpain. The protease activation was accompanied by a decrease in the E-cadherin level and formation of calpain-specific breakdown products of alphaII-spectrin. A calpain-specific cleavage product of vinculin appeared concomitantly with changes in the actin filament organization. No effect of CCK on calpastatin was found. Inhibition of calpain by ZVP reduced CCK-induced damage of the actin-associated proteins and the cellular ultrastructure including the actin cytoskeleton. The results suggest that CCK-induced acinar cell damage requires activation of calpain and that the actin cytoskeleton belongs to the cellular targets of the protease.

Particle size-dependent radical generation from wildland fire smoke.

PubMed

Leonard, Stephen S; Castranova, Vince; Chen, Bean T; Schwegler-Berry, Diane; Hoover, Mark; Piacitelli, Chris; Gaughan, Denise M

2007-07-01

Firefighting, along with construction, mining and agriculture, ranks among the most dangerous occupations. In addition, the work environment of firefighters is unlike that of any other occupation, not only because of the obvious physical hazards but also due to the respiratory and systemic health hazards of smoke inhalation resulting from combustion. A significant amount of research has been devoted to studying municipal firefighters; however, these studies may not be useful in wildland firefighter exposures, because the two work environments are so different. Not only are wildland firefighters exposed to different combustion products, but their exposure profiles are different. The combustion products wildland firefighters are exposed to can vary greatly in characteristics due to the type and amount of material being burned, soil conditions, temperature and exposure time. Smoke inhalation is one of the greatest concerns for firefighter health and it has been shown that the smoke consists of a large number of particles. These smoke particles contain intermediates of hydrogen, carbon and oxygen free radicals, which may pose a potential health risk. Our investigation looked into the involvement of free radicals in smoke toxicity and the relationship between particle size and radical generation. Samples were collected in discrete aerodynamic particle sizes from a wildfire in Alaska, preserved and then shipped to our laboratory for analysis. Electron spin resonance was used to measure carbon-centered as well as hydroxyl radicals produced by a Fenton-like reaction with wildfire smoke. Further study of reactive oxygen species was conducted using analysis of cellular H(2)O(2) generation, lipid peroxidation of cellular membranes and DNA damage. Results demonstrate that coarse size-range particles contained more carbon radicals per unit mass than the ultrafine particles; however, the ultrafine particles generated more *OH radicals in the acellular Fenton-like reaction. The ultrafine particles also caused significant increases in H(2)O(2) production by monocytes and lipid peroxidation. All particle sizes showed the ability to cause DNA damage. These results indicate that the radical generation and the damage caused by them is not only a function of surface area but is also influenced by changing chemical and other characteristics due to particle size.

Space Biophysics: Accomplishments, Trends, Challenges

NASA Technical Reports Server (NTRS)

Smith, Jeffrey D.

2015-01-01

Physics and biology are inextricably linked. All the chemical and biological processes of life are dutifully bound to follow the rules and laws of physics. In space, these physical laws seem to turn on their head and biological systems, from microbes to humans, adapt and evolve in myriad ways to cope with the changed physical influences of the space environment. Gravity is the most prominent change in space that influences biology. In microgravity, the physical processes of sedimentation, density-driven convective flow, influence of surface tension and fluid pressure profoundly influence biology at the molecular and cellular level as well as at the whole-body level. Gravity sensing mechanisms are altered, structural and functional components of biology (such as bone and muscle) are reduced and changes in the way fluids and gasses behave also drive the way microbial systems and biofilms grow as well as the way plants and animals adapt. The radiation environment also effects life in space. Solar particle events and high energy cosmic radiation can cause serious damage to DNA and other biomolecules. The results can cause mutation, cellular damage or death, leading to health consequences of acute radiation damage or long-term health consequences such as increased cancer risk. Space Biophysics is the study and utilization of physical changes in space that cause changes in biological systems. The unique physical environment in space has been used successfully to grow high-quality protein crystals and 3D tissue cultures that could not be grown in the presence of unidirectional gravitational acceleration here on Earth. All biological processes that change in space have their root in a biophysical alteration due to microgravity and/or the radiation environment of space. In order to fully-understand the risks to human health in space and to fully-understand how humans, plants, animals and microbes can safely and effectively travel and eventually live for long periods beyond the protective environment of Earth, the biophysical properties underlying these changes must be studied, characterized and understood. This lecture reviews the current state of NASA biophysics research accomplishments and identifies future trends and challenges for biophysics research on the International Space Station and beyond.

Concerted action of Nrf2-ARE pathway, MRN complex, HMGB1 and inflammatory cytokines - Implication in modification of radiation damage

PubMed Central

Anuranjani; Bala, Madhu

2014-01-01

Whole body exposure to low linear energy transfer (LET) ionizing radiations (IRs) damages vital intracellular bio-molecules leading to multiple cellular and tissue injuries as well as pathophysiologies such as inflammation, immunosuppression etc. Nearly 70% of damage is caused indirectly by radiolysis of intracellular water leading to formation of reactive oxygen species (ROS) and free radicals and producing a state of oxidative stress. The damage is also caused by direct ionization of biomolecules. The type of radiation injuries is dependent on the absorbed radiation dose. Sub-lethal IR dose produces more of DNA base damages, whereas higher doses produce more DNA single strand break (SSBs), and double strand breaks (DSBs). The Nrf2-ARE pathway is an important oxidative stress regulating pathway. The DNA DSBs repair regulated by MRN complex, immunomodulation and inflammation regulated by HMGB1 and various types of cytokines are some of the key pathways which interact with each other in a complex manner and modify the radiation response. Because the majority of radiation damage is via oxidative stress, it is essential to gain in depth understanding of the mechanisms of Nrf2-ARE pathway and understand its interactions with MRN complex, HMGB1 and cytokines to increase our understanding on the radiation responses. Such information is of tremendous help in development of medical radiation countermeasures, radioprotective drugs and therapeutics. Till date no approved and safe countermeasure is available for human use. This study reviews the Nrf2-ARE pathway and its crosstalk with MRN-complex, HMGB1 and cytokines (TNF-a, IL-6, IFN-? etc.). An attempt is also made to review the modification of some of these pathways in presence of selected antioxidant radioprotective compounds or herbal extracts. PMID:25009785

Mathematical Modeling of Early Cellular Innate and Adaptive Immune Responses to Ischemia/Reperfusion Injury and Solid Organ Allotransplantation

PubMed Central

Day, Judy D.; Metes, Diana M.; Vodovotz, Yoram

2015-01-01

A mathematical model of the early inflammatory response in transplantation is formulated with ordinary differential equations. We first consider the inflammatory events associated only with the initial surgical procedure and the subsequent ischemia/reperfusion (I/R) events that cause tissue damage to the host as well as the donor graft. These events release damage-associated molecular pattern molecules (DAMPs), thereby initiating an acute inflammatory response. In simulations of this model, resolution of inflammation depends on the severity of the tissue damage caused by these events and the patient’s (co)-morbidities. We augment a portion of a previously published mathematical model of acute inflammation with the inflammatory effects of T cells in the absence of antigenic allograft mismatch (but with DAMP release proportional to the degree of graft damage prior to transplant). Finally, we include the antigenic mismatch of the graft, which leads to the stimulation of potent memory T cell responses, leading to further DAMP release from the graft and concomitant increase in allograft damage. Regulatory mechanisms are also included at the final stage. Our simulations suggest that surgical injury and I/R-induced graft damage can be well-tolerated by the recipient when each is present alone, but that their combination (along with antigenic mismatch) may lead to acute rejection, as seen clinically in a subset of patients. An emergent phenomenon from our simulations is that low-level DAMP release can tolerize the recipient to a mismatched allograft, whereas different restimulation regimens resulted in an exaggerated rejection response, in agreement with published studies. We suggest that mechanistic mathematical models might serve as an adjunct for patient- or sub-group-specific predictions, simulated clinical studies, and rational design of immunosuppression. PMID:26441988

The toxicity, in vitro, of silicon carbide whiskers.

PubMed

Vaughan, G L; Jordan, J; Karr, S

1991-10-01

To mouse cells in culture, SiC whiskers (SiCW) and asbestos are similarly cytotoxic, disrupting cell membranes and killing cells. Both shorten cell generation time, increase the rate of DNA synthesis, increase total cell DNA content, and cause a loss in growth control often associated with malignant cellular transformation. Within the narrow size range of materials examined, the amount of damage appeared to be more a function of the number of whiskers present than of their size. Silicon carbide whiskers, if mishandled, may pose a serious health hazard to humans.

Toxic Proteins in Neurodegenerative Disease

NASA Astrophysics Data System (ADS)

Taylor, J. Paul; Hardy, John; Fischbeck, Kenneth H.

2002-06-01

A broad range of neurodegenerative disorders is characterized by neuronal damage that may be caused by toxic, aggregation-prone proteins. As genes are identified for these disorders and cell culture and animal models are developed, it has become clear that a major effect of mutations in these genes is the abnormal processing and accumulation of misfolded protein in neuronal inclusions and plaques. Increased understanding of the cellular mechanisms for disposal of abnormal proteins and of the effects of toxic protein accumulation on neuronal survival may allow the development of rational, effective treatment for these disorders.

Genomic instability and bystander effects: a paradigm shift in radiation biology?

NASA Technical Reports Server (NTRS)

Morgan, William F.

2002-01-01

A basic paradigm in radiobiology is that, following exposure to ionizing radiation, the deposition of energy in the cell nucleus and the resulting damage to DNA, the principal target, are responsible for the radiation's deleterious biological effects. Findings in two rapidly expanding fields of research--radiation-induced genomic instability and bystander effects--have caused us to reevaluate these central tenets. In this article, the potential influence of induced genomic instability and bystander effects on cellular injury after exposure to low-level radiation will be reviewed.

Effects of welding fumes of differing composition and solubility on free radical production and acute lung injury and inflammation in rats.

PubMed

Taylor, Michael D; Roberts, Jenny R; Leonard, Stephen S; Shi, Xianglin; Antonini, James M

2003-09-01

The goals of this study were to examine acute lung damage and inflammation, as well as free radical production, caused by welding fumes of different chemical compositions and solubilities. The fumes were from a gas metal arc welding using a mild-steel (GMA-MS) or stainless-steel electrode (GMA-SS) and a manual metal arc welding using a stainless-steel electrode (MMA-SS), which was further separated into soluble and insoluble fractions. The MMA-SS was the only fume to contain soluble chromium. Free radical production was observed only in suspensions of MMA-SS fume under various conditions. Male Sprague-Dawley rats were intratracheally instilled with either a welding fume suspension at 2 mg/rat or a saline vehicle, and various parameters of inflammation and damage were measured at 3 h and days 1, 3, and 6. Only the MMA-SS treatment caused a continued increase in lung weight until day 6 and elevated lipid peroxidation at day 3. All of the fumes caused increases in macrophages and neutrophils obtained by lavage, but the increased cellularity was extended through day 6 following the MMA-SS treatment only. Only the MMA-SS treatment led to an increased recovery of eosinophils and damage to the alveolar-capillary barrier. While all of the fumes produced increases in cytotoxicity, the MMA-SS treatment caused the maximal response at day 3. These findings indicate that different welding fumes caused varied responses in the lungs of rats, correlated to their metal composition and ability to produce free radicals. Additionally, both the soluble and insoluble fractions of the MMA-SS fume were required to produce most effects, indicating that the responses are not dependent exclusively on the soluble metals.

The antibiotic activity and mechanisms of sugarcane (Saccharum officinarum L.) bagasse extract against food-borne pathogens.

PubMed

Zhao, Yi; Chen, Mingshun; Zhao, Zhengang; Yu, Shujuan

2015-10-15

Sugarcane bagasse contains natural compositions that can significantly inhibit food-borne pathogens growth. In the present study, the phenolic content in sugarcane bagasse was detected as higher than 4 mg/g dry bagasse, with 470 mg quercetin/g polyphenol. The sugarcane bagasse extract showed bacteriostatic activity against the growth of Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salomonella typhimurium. Additionally, the sugarcane bagasse extract can increase the electric conductivity of bacterial cell suspensions causing cellular leaking of electrolytes. Results of sodium dodecyl sulfate polyacrylamide gel electrophoresis suggested the antibacterial mechanism was probably due to the damaged cellular proteins by sugarcane bagasse extract. The results of scanning electron microscopy and transmission electron microscopy showed that the sugarcane bagasse extract might change cell morphology and internal structure. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of iron in brain ageing and neurodegenerative disorders

PubMed Central

Ward, Roberta J; Zucca, Fabio A; Duyn, Jeff H; Crichton, Robert R; Zecca, Luigi

2017-01-01

In the CNS, iron in several proteins is involved in many important processes such as oxygen transportation, oxidative phosphorylation, myelin production, and the synthesis and metabolism of neurotransmitters. Abnormal iron homoeostasis can induce cellular damage through hydroxyl radical production, which can cause the oxidation and modification of lipids, proteins, carbohydrates, and DNA. During ageing, different iron complexes accumulate in brain regions associated with motor and cognitive impairment. In various neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, changes in iron homoeostasis result in altered cellular iron distribution and accumulation. MRI can often identify these changes, thus providing a potential diagnostic biomarker of neurodegenerative diseases. An important avenue to reduce iron accumulation is the use of iron chelators that are able to cross the blood–brain barrier, penetrate cells, and reduce excessive iron accumulation, thereby affording neuroprotection. PMID:25231526

Effects of reactive oxygen species and interplay of antioxidants during physical exercise in skeletal muscles.

PubMed

Thirupathi, Anand; Pinho, Ricardo A

2018-05-01

A large number of researches have led to a substantial growth of knowledge about exercise and oxidative stress. Initial investigations reported that physical exercise generates free radical-mediated damages to cells; however, in recent years, studies have shown that regular exercise can upregulate endogenous antioxidants and reduce oxidative damage. Yet, strenuous exercise perturbs the antioxidant system by increasing the reactive oxygen species (ROS) content. These alterations in the cellular environment seem to occur in an exercise type-dependent manner. The source of ROS generation during exercise is debatable, but now it is well established that both contracting and relaxing skeletal muscles generate reactive oxygen species and reactive nitrogen species. In particular, exercises of higher intensity and longer duration can cause oxidative damage to lipids, proteins, and nucleotides in myocytes. In this review, we summarize the ROS effects and interplay of antioxidants in skeletal muscle during physical exercise. Additionally, we discuss how ROS-mediated signaling influences physical exercise in antioxidant system.

Hydroxynonenal and uncoupling proteins: a model for protection against oxidative damage.

PubMed

Echtay, Karim S; Pakay, Julian L; Esteves, Telma C; Brand, Martin D

2005-01-01

In this mini review we summarize recent studies from our laboratory that show the involvement of superoxide and the lipid peroxidation product 4-hydroxynonenal in the regulation of mitochondrial uncoupling. Superoxide produced during mitochondrial respiration is a major cause of the cellular oxidative damage that may underlie degenerative diseases and ageing. Superoxide production is very sensitive to the magnitude of the mitochondrial protonmotive force, so can be strongly decreased by mild uncoupling. Superoxide is able to give rise to other reactive oxygen species, which elicit deleterious effects primarily by oxidizing intracellular components, including lipids, DNA and proteins. Superoxide-induced lipid peroxidation leads to the production of reactive aldehydes, including 4-hydroxynonenal. These aldehydic lipid peroxidation products are in turn able to modify proteins such as mitochondrial uncoupling proteins and the adenine nucleotide translocase, converting them into active proton transporters. This activation induces mild uncoupling and so diminishes mitochondrial superoxide production, hence protecting against disease and oxidative damage at the expense of energy production.

Antibacterial activity and mechanism of berberine against Streptococcus agalactiae

PubMed Central

Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

2015-01-01

The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually. PMID:26191220

Antibacterial activity and mechanism of berberine against Streptococcus agalactiae.

PubMed

Peng, Lianci; Kang, Shuai; Yin, Zhongqiong; Jia, Renyong; Song, Xu; Li, Li; Li, Zhengwen; Zou, Yuanfeng; Liang, Xiaoxia; Li, Lixia; He, Changliang; Ye, Gang; Yin, Lizi; Shi, Fei; Lv, Cheng; Jing, Bo

2015-01-01

The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kao, Shyan-Yuan, E-mail: shyan-yuan_kao@meei.harvard.edu

Mutation of parkin is one of the most prevalent causes of autosomal recessive Parkinson's disease (PD). Parkin is an E3 ubiquitin ligase that acts on a variety of substrates, resulting in polyubiquitination and degradation by the proteasome or monoubiquitination and regulation of biological activity. However, the cellular functions of parkin that relate to its pathological involvement in PD are not well understood. Here we show that parkin is essential for optimal repair of DNA damage. Parkin-deficient cells exhibit reduced DNA excision repair that can be restored by transfection of wild-type parkin, but not by transfection of a pathological parkin mutant.more » Parkin also protects against DNA damage-induced cell death, an activity that is largely lost in the pathological mutant. Moreover, parkin interacts with the proliferating cell nuclear antigen (PCNA), a protein that coordinates DNA excision repair. These results suggest that parkin promotes DNA repair and protects against genotoxicity, and implicate DNA damage as a potential pathogenic mechanism in PD.« less

The role of oxidative stress in the metabolic syndrome.

PubMed

Whaley-Connell, Adam; McCullough, Peter A; Sowers, James R

2011-01-01

Loss of reduction-oxidation (redox) homeostasis and generation of excess free oxygen radicals play an important role in the pathogenesis of diabetes, hypertension, and consequent cardiovascular disease. Reactive oxygen species are integral in routine in physiologic mechanisms. However, loss of redox homeostasis contributes to proinflammatory and profibrotic pathways that promote impairments in insulin metabolic signaling, reduced endothelial-mediated vasorelaxation, and associated cardiovascular and renal structural and functional abnormalities. Redox control of metabolic function is a dynamic process with reversible pro- and anti-free radical processes. Labile iron is necessary for the catalysis of superoxide anion, hydrogen peroxide, and the generation of the damaging hydroxyl radical. Acute hypoxia and cellular damage in cardiovascular tissue liberate larger amounts of cytosolic and extracellular iron that is poorly liganded; thus, large increases in the generation of oxygen free radicals are possible, causing tissue damage. The understanding of iron and the imbalance of redox homeostasis within the vasculature is integral in hypertension and progression of metabolic dysregulation that contributes to insulin resistance, endothelial dysfunction, and cardiovascular and kidney disease.

Ubiad1 Is an Antioxidant Enzyme that Regulates eNOS Activity by CoQ10 Synthesis

PubMed Central

Mugoni, Vera; Postel, Ruben; Catanzaro, Valeria; De Luca, Elisa; Turco, Emilia; Digilio, Giuseppe; Silengo, Lorenzo; Murphy, Michael P.; Medana, Claudio; Stainier, Didier Y.R.; Bakkers, Jeroen; Santoro, Massimo M.

2013-01-01

Summary Protection against oxidative damage caused by excessive reactive oxygen species (ROS) by an antioxidant network is essential for the health of tissues, especially in the cardiovascular system. Here, we identified a gene with important antioxidant features by analyzing a null allele of zebrafish ubiad1, called barolo (bar). bar mutants show specific cardiovascular failure due to oxidative stress and ROS-mediated cellular damage. Human UBIAD1 is a nonmitochondrial prenyltransferase that synthesizes CoQ10 in the Golgi membrane compartment. Loss of UBIAD1 reduces the cytosolic pool of the antioxidant CoQ10 and leads to ROS-mediated lipid peroxidation in vascular cells. Surprisingly, inhibition of eNOS prevents Ubiad1-dependent cardiovascular oxidative damage, suggesting a crucial role for this enzyme and nonmitochondrial CoQ10 in NO signaling. These findings identify UBIAD1 as a nonmitochondrial CoQ10-forming enzyme with specific cardiovascular protective function via the modulation of eNOS activity. PMID:23374346

Multifunctional Role of ATM/Tel1 Kinase in Genome Stability: From the DNA Damage Response to Telomere Maintenance

PubMed Central

2014-01-01

The mammalian protein kinase ataxia telangiectasia mutated (ATM) is a key regulator of the DNA double-strand-break response and belongs to the evolutionary conserved phosphatidylinositol-3-kinase-related protein kinases. ATM deficiency causes ataxia telangiectasia (AT), a genetic disorder that is characterized by premature aging, cerebellar neuropathy, immunodeficiency, and predisposition to cancer. AT cells show defects in the DNA damage-response pathway, cell-cycle control, and telomere maintenance and length regulation. Likewise, in Saccharomyces cerevisiae, haploid strains defective in the TEL1 gene, the ATM ortholog, show chromosomal aberrations and short telomeres. In this review, we outline the complex role of ATM/Tel1 in maintaining genomic stability through its control of numerous aspects of cellular survival. In particular, we describe how ATM/Tel1 participates in the signal transduction pathways elicited by DNA damage and in telomere homeostasis and its importance as a barrier to cancer development. PMID:25247188

Protective effects of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone to PC12 cells against cytotoxicity induced by hydrogen peroxide.

PubMed

Su, Ming-Yuan; Huang, Hai-Ya; Li, Lin; Lu, Yan-Hua

2011-01-26

Oxidative stress has been considered as a major cause of cellular injuries in various clinical abnormalities. One of the possible ways to prevent reactive oxygen species (ROS)-mediated cellular injury is dietary or pharmaceutical therapies to augment the endogenous antioxidant defense capacity. The present study found that 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC), a chalcone isolated from the buds of Cleistocalyx operculatus, possessed cytoprotective activity in PC12 cells treated with H(2)O(2). The results showed that DMC could effectively increase cell viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) reduction], decrease the cell apoptotic percentage [annexin V/propidium iodide (AV/PI) assay], prevent the membrane from damage [lactate dehydrogenase (LDH) release], scavenge ROS formation, reduce caspase-3 activity, and attenuate the decrease of mitochondrial membrane potential (MMP) in PC12 cells treated with H(2)O(2). Meanwhile, DMC increased the catalytic activity of superoxide dismutase (SOD) and the cellular amount of glutathione (GSH), decreased the cellular amount of malondialdehyde (MDA), and decreased the production of lipid peroxidation in PC12 cells treated with H(2)O(2).

Trypanosoma vivax Adhesion to Red Blood Cells in Experimentally Infected Sheep

PubMed Central

Boada-Sucre, Alpidio A.; Rossi Spadafora, Marcello Salvatore; Tavares-Marques, Lucinda M.; Finol, Héctor J.; Reyna-Bello, Armando

2016-01-01

Trypanosomosis, a globally occurring parasitic disease, poses as a major obstacle to livestock production in tropical and subtropical regions resulting in tangible economic losses. In Latin America including Venezuela, trypanosomosis of ruminants is mainly caused by Trypanosoma vivax. Biologically active substances produced from trypanosomes, as well as host-trypanosome cellular interactions, contribute to the pathogenesis of anemia in an infection. The aim of this study was to examine with a scanning electron microscope the cellular interactions and alterations in ovine red blood cells (RBC) experimentally infected with T. vivax. Ovine infection resulted in changes of RBC shape as well as the formation of surface holes or vesicles. A frequent observation was the adhesion to the ovine RBC by the trypanosome's free flagellum, cell body, or attached flagellum in a process mediated by the filopodia emission from the trypanosome surface. The observed RBC alterations are caused by mechanical and biochemical damage from host-parasite interactions occurring in the bloodstream. The altered erythrocytes are prone to mononuclear phagocytic removal contributing to the hematocrit decrease during infection. PMID:27293960

Trypanosoma vivax Adhesion to Red Blood Cells in Experimentally Infected Sheep.

PubMed

Boada-Sucre, Alpidio A; Rossi Spadafora, Marcello Salvatore; Tavares-Marques, Lucinda M; Finol, Héctor J; Reyna-Bello, Armando

2016-01-01

Trypanosomosis, a globally occurring parasitic disease, poses as a major obstacle to livestock production in tropical and subtropical regions resulting in tangible economic losses. In Latin America including Venezuela, trypanosomosis of ruminants is mainly caused by Trypanosoma vivax. Biologically active substances produced from trypanosomes, as well as host-trypanosome cellular interactions, contribute to the pathogenesis of anemia in an infection. The aim of this study was to examine with a scanning electron microscope the cellular interactions and alterations in ovine red blood cells (RBC) experimentally infected with T. vivax. Ovine infection resulted in changes of RBC shape as well as the formation of surface holes or vesicles. A frequent observation was the adhesion to the ovine RBC by the trypanosome's free flagellum, cell body, or attached flagellum in a process mediated by the filopodia emission from the trypanosome surface. The observed RBC alterations are caused by mechanical and biochemical damage from host-parasite interactions occurring in the bloodstream. The altered erythrocytes are prone to mononuclear phagocytic removal contributing to the hematocrit decrease during infection.

The calcium paradox - What should we have to fear?

PubMed Central

de Oliveira, Marcos Aurélio Barboza; Brandi, Antônio Carlos; dos Santos, Carlos Alberto; Botelho, Paulo Henrique Husseni; Cortez, José Luís Lasso; Goissis, Gilberto; Braile, Domingo Marcolino

2014-01-01

The calcium paradox was first mentioned in 1966 by Zimmerman et al. Thereafter gained great interest from the scientific community due to the fact of the absence of calcium ions in heart muscle cells produce damage similar to ischemia-reperfusion. Although not all known mechanisms involved in cellular injury in the calcium paradox intercellular connection maintained only by nexus seems to have a key role in cellular fragmentation. The addition of small concentrations of calcium, calcium channel blockers, and hyponatraemia hypothermia are important to prevent any cellular damage during reperfusion solutions with physiological concentration of calcium. PMID:25140476

Differential responses of juvenile and adult South African abalone (Haliotis midae Linnaeus) to low and high oxygen levels.

PubMed

Vosloo, Andre; Laas, Anél; Vosloo, Dalene

2013-01-01

Marine invertebrates have evolved multiple responses to naturally variable environmental oxygen, all aimed at either maintaining cellular oxygen homeostasis or limiting cellular damage during or after hypoxic or hyperoxic events. We assessed organismal (rates of oxygen consumption and ammonia excretion) and cellular (heat shock protein expression, anti-oxidant enzymes) responses of juvenile and adult abalone exposed to low (~83% of saturation), intermediate (~95% of saturation) and high (~115% of saturation) oxygen levels for one month. Using the Comet assay, we measured DNA damage to determine whether the observed trends in the protective responses were sufficient to prevent oxidative damage to cells. Juveniles were unaffected by moderately hypoxic and hyperoxic conditions. Elevated basal rates of superoxide dismutase, glutathione peroxidase and catalase were sufficient to prevent DNA fragmentation and protein damage. Adults, with their lower basal rate of anti-oxidant enzymes, had increased DNA damage under hypoxic and hyperoxic conditions, indicating that the antioxidant enzymes were unable to prevent oxidative damage under hypoxic and hyperoxic conditions. The apparent insensitivity of juvenile abalone to decreased and increased oxygen might be related to their life history and development in algal and diatom biofilms where they are exposed to extreme diurnal fluctuations in dissolved oxygen levels. Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical changes demonstrated in cartilage by synchrotron infrared microspectroscopy in an antibody-induced murine model of rheumatoid arthritis

NASA Astrophysics Data System (ADS)

Croxford, Allyson M.; Selva Nandakumar, Kutty; Holmdahl, Rikard; Tobin, Mark J.; McNaughton, Don; Rowley, Merrill J.

2011-06-01

Collagen antibody-induced arthritis develops in mice following passive transfer of monoclonal antibodies (mAbs) to type II collagen (CII) and is attributed to effects of proinflammatory immune complexes, but transferred mAbs may react directly and damagingly with CII. To determine whether such mAbs cause cartilage damage in vivo in the absence of inflammation, mice lacking complement factor 5 that do not develop joint inflammation were injected intravenously with two arthritogenic mAbs to CII, M2139 and CIIC1. Paws were collected at day 3, decalcified, paraffin embedded, and 5-μm sections were examined using standard histology and synchrotron Fourier-transform infrared microspectroscopy (FTIRM). None of the mice injected with mAb showed visual or histological evidence of inflammation but there were histological changes in the articular cartilage including loss of proteoglycan and altered chondrocyte morphology. Findings using FTIRM at high lateral resolution revealed loss of collagen and the appearance of a new peak at 1635 cm-1 at the surface of the cartilage interpreted as cellular activation. Thus, we demonstrate the utility of synchrotron FTIRM for examining chemical changes in diseased cartilage at the microscopic level and establish that arthritogenic mAbs to CII do cause cartilage damage in vivo in the absence of inflammation.

Electro-mechanical response of a 3D nerve bundle model to mechanical loads leading to axonal injury.

PubMed

Cinelli, I; Destrade, M; Duffy, M; McHugh, P

2018-03-01

Traumatic brain injuries and damage are major causes of death and disability. We propose a 3D fully coupled electro-mechanical model of a nerve bundle to investigate the electrophysiological impairments due to trauma at the cellular level. The coupling is based on a thermal analogy of the neural electrical activity by using the finite element software Abaqus CAE 6.13-3. The model includes a real-time coupling, modulated threshold for spiking activation, and independent alteration of the electrical properties for each 3-layer fibre within a nerve bundle as a function of strain. Results of the coupled electro-mechanical model are validated with previously published experimental results of damaged axons. Here, the cases of compression and tension are simulated to induce (mild, moderate, and severe) damage at the nerve membrane of a nerve bundle, made of 4 fibres. Changes in strain, stress distribution, and neural activity are investigated for myelinated and unmyelinated nerve fibres, by considering the cases of an intact and of a traumatised nerve membrane. A fully coupled electro-mechanical modelling approach is established to provide insights into crucial aspects of neural activity at the cellular level due to traumatic brain injury. One of the key findings is the 3D distribution of residual stresses and strains at the membrane of each fibre due to mechanically induced electrophysiological impairments, and its impact on signal transmission. Copyright © 2017 John Wiley & Sons, Ltd.

Protein Arginine Methyltransferase 7 Regulates Cellular Response to DNA Damage by Methylating Promoter Histones H2A and H4 of the Polymerase δ Catalytic Subunit Gene, POLD1*

PubMed Central

Karkhanis, Vrajesh; Wang, Li; Tae, Sookil; Hu, Yu-Jie; Imbalzano, Anthony N.; Sif, Saïd

2012-01-01

Covalent modification of histones by protein arginine methyltransferases (PRMTs) impacts genome organization and gene expression. In this report, we show that PRMT7 interacts with the BRG1-based hSWI/SNF chromatin remodeling complex and specifically methylates histone H2A Arg-3 (H2AR3) and histone H4 Arg-3 (H4R3). To elucidate the biological function of PRMT7, we knocked down its expression in NIH 3T3 cells and analyzed global gene expression. Our findings show that PRMT7 negatively regulates expression of genes involved in DNA repair, including ALKBH5, APEX2, POLD1, and POLD2. Chromatin immunoprecipitation (ChIP) revealed that PRMT7 and dimethylated H2AR3 and H4R3 are enriched at target DNA repair genes in parental cells, whereas PRMT7 knockdown caused a significant decrease in PRMT7 recruitment and H2AR3/H4R3 methylation. Decreased PRMT7 expression also resulted in derepression of target DNA repair genes and enhanced cell resistance to DNA-damaging agents. Furthermore, we show that BRG1 co-localizes with PRMT7 on target promoters and that expression of a catalytically inactive form of BRG1 results in derepression of PRMT7 target DNA repair genes. Remarkably, reducing expression of individual PRMT7 target DNA repair genes showed that only the catalytic subunit of DNA polymerase, POLD1, was able to resensitize PRMT7 knock-down cells to DNA-damaging agents. These results provide evidence for the important role played by PRMT7 in epigenetic regulation of DNA repair genes and cellular response to DNA damage. PMID:22761421

Aldosterone Activates Transcription Factor Nrf2 in Kidney Cells Both In Vitro and In Vivo

PubMed Central

Oteiza, Patricia I.; Link, Samuel; Hey, Valentin; Stopper, Helga; Schupp, Nicole

2014-01-01

Abstract Aims: An increased kidney cancer risk was found in hypertensive patients, who frequently exhibit hyperaldosteronism, known to contribute to kidney injury, with oxidative stress playing an important role. The capacity of kidney cells to up-regulate transcription factor nuclear factor-erythroid-2-related factor 2 (Nrf2), a key regulator of the cellular antioxidative defense, as a prevention of aldosterone-induced oxidative damage was investigated both in vitro and in vivo. Results: Aldosterone activated Nrf2 and increased the expression of enzymes involved in glutathione (GSH) synthesis and detoxification. This activation depended on the mineralocorticoid receptor (MR) and oxidative stress. In vitro, Nrf2 activation, GSH amounts, and target gene levels decreased after 24 h, while oxidant levels remained high. Nrf2 activation could not protect cells against oxidative DNA damage, as aldosterone-induced double-strand breaks and 7,8-dihydro-8-oxo-guanine (8-oxodG) lesions steadily rose. The Nrf2 activator sulforaphane enhanced the Nrf2 response both in vitro and in vivo, thereby preventing aldosterone-induced DNA damage. In vivo, Nrf2 activation further had beneficial effects on the aldosterone-caused blood pressure increase and loss of kidney function. Innovation: This is the first study showing the activation of Nrf2 by aldosterone. Moreover, the results identify sulforaphane as a substance that is capable of preventing aldosterone-induced damage both in vivo and in vitro. Conclusion: Aldosterone-induced Nrf2 adaptive response cannot neutralize oxidative actions of chronically increased aldosterone, which, therefore could be causally involved in the increased cancer incidence of hypertensive individuals. Enhancing the cellular antioxidative defense with sulforaphane might exhibit beneficial effects. Antioxid. Redox Signal. 21, 2126–2142. PMID:24512358

Deletion of angiotensin II type 1 receptor gene or scavenge of superoxide prevents chronic alcohol-induced aortic damage and remodelling.

PubMed

Bai, Yang; Tan, Yi; Wang, Bo; Miao, Xiao; Chen, Qiang; Zheng, Yang; Cai, Lu

2012-10-01

To investigate whether chronic alcohol consumption induces vascular injury via angiotensin II (Ang II) type 1 (AT1) receptor-dependent superoxide generation, male transgenic mice with knockout of AT1 gene (AT1-KO) and age-matched wild-type (WT) C57BL/6 mice were pair-fed a modified Lieber-DeCarli alcohol or isocaloric maltose dextrin control liquid diet for 2 months. Ethanol content (%, W/V) in the diet was 4.8 (34% of total calories) at initiation, and gradually increased up to 5.4 (38% of total calories). For some WT mice with and without alcohol treatment, superoxide dismutase mimetic (MnTMPyP) was given simultaneously by intraperitoneal injection at 5 mg/kg body weight daily for 2 months. At the end of studies, aortas were harvested for histopathological and immunohistochemical examination. Significant increases in the wall thickness and structural disarrangement of aorta were found in alcohol group, along with significant increases in aortic oxidative and/or nitrosative damage, expressions of NADPH oxidases (NOXs), inflammatory response, cell death and proliferation, and remodelling (fibrosis). However, these pathological changes were completely attenuated in alcohol-treated AT1-KO mice or in alcohol-treated WT mice that were also simultaneously treated with MnTMPyP for 2 months. These results suggest that chronic alcohol consumption may activate NOX via Ang II/AT1 receptor, to generate superoxide and associated peroxynitrite that in turn causes aortic nitrosative damage, inflammation, cell death and proliferation, and remodelling. Therefore, blocking Ang II/AT1 system or scavenging superoxide may become a potential preventive and/therapeutic approach to alcoholic vascular damage. © 2012 The Authors Journal of Cellular and Molecular Medicine © 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

[Regression and therapy-resistance of primary liver tumors and liver metastases after regional chemotherapy and local tumor ablation].

PubMed

Fischer, H-P

2005-05-01

High dosage regional chemotherapy, chemoembolization and other methods of regional treatment are commonly used to treat unresectable primary liver malignancies and liver metastases. In liver malignancies of childhood neoadjuvant chemotherapy is successfully combined with surgical treatment. Chemotherapy and local tumor ablation lead to characteristic histomorphologic changes: Complete destruction of the tumor tissue and its vascular bed is followed by encapsulated necroses. After selective eradication of the tumor cells under preservation of the fibrovasular bed the tumor is replaced by hypocellular edematous and fibrotic tissue. If completely damaged tumor tissue is absorbed quickly, the tumor area is replaced by regenerating liver tissue. Obliterating fibrohyalinosis of tumor vessels, and perivascular edema or necrosis indicate tissue damage along the vascular bed. Degenerative pleomorphism of tumor cells, steatosis, hydropic swelling and Malloryhyalin in HCC can represent cytologic findings of cytotoxic cellular damage. Macroscopic type of HCC influences significantly the response to treatment. Multinodular HCC often contain viable tumor nodules close to destroyed nodules after treatment. Encapsulated uninodular tumors undergo complete necrosis much easier. Large size and a tumor capsule limitate the effect of percutaneous injection of ethanol into HCC. In carcinomas with an infiltrating border, especially in metastases of adenocarcinomas and hepatic cholangiocarcinoma cytostatic treatment damages the tumor tissue mainly in the periphery. Nevertheless the infiltrating rim, portal veins, lymphatic spaces and bile ducts as well as the angle between liver capsule, tumor nodule and bordering parenchyma are the main refugees of viable tumor tissue even after high dosage regional chemotherapy. This local resistance is caused by special local conditions of vascularization and perfusion. These residues are the source of local tumor progression and distant metastases. Besides intrinsic cellular mechanisms architectural, and microenvironmental factors relevantly limitate the effect of intensive locoregional therapy.

Protein arginine methyltransferase 7 regulates cellular response to DNA damage by methylating promoter histones H2A and H4 of the polymerase δ catalytic subunit gene, POLD1.

PubMed

Karkhanis, Vrajesh; Wang, Li; Tae, Sookil; Hu, Yu-Jie; Imbalzano, Anthony N; Sif, Saïd

2012-08-24

Covalent modification of histones by protein arginine methyltransferases (PRMTs) impacts genome organization and gene expression. In this report, we show that PRMT7 interacts with the BRG1-based hSWI/SNF chromatin remodeling complex and specifically methylates histone H2A Arg-3 (H2AR3) and histone H4 Arg-3 (H4R3). To elucidate the biological function of PRMT7, we knocked down its expression in NIH 3T3 cells and analyzed global gene expression. Our findings show that PRMT7 negatively regulates expression of genes involved in DNA repair, including ALKBH5, APEX2, POLD1, and POLD2. Chromatin immunoprecipitation (ChIP) revealed that PRMT7 and dimethylated H2AR3 and H4R3 are enriched at target DNA repair genes in parental cells, whereas PRMT7 knockdown caused a significant decrease in PRMT7 recruitment and H2AR3/H4R3 methylation. Decreased PRMT7 expression also resulted in derepression of target DNA repair genes and enhanced cell resistance to DNA-damaging agents. Furthermore, we show that BRG1 co-localizes with PRMT7 on target promoters and that expression of a catalytically inactive form of BRG1 results in derepression of PRMT7 target DNA repair genes. Remarkably, reducing expression of individual PRMT7 target DNA repair genes showed that only the catalytic subunit of DNA polymerase, POLD1, was able to resensitize PRMT7 knock-down cells to DNA-damaging agents. These results provide evidence for the important role played by PRMT7 in epigenetic regulation of DNA repair genes and cellular response to DNA damage.

Preferential mitochondrial DNA injury caused by glucose oxidase as a steady generator of hydrogen peroxide in human fibroblasts.

PubMed

Salazar, J J; Van Houten, B

1997-11-01

To test the hypothesis that mitochondrial DNA (mtDNA) is more prone to reactive oxygen species (ROS) damage than nuclear DNA, a continuous flux of hydrogen peroxide (H2O2) was produced with the glucose/glucose oxidase system. Using a horse radish peroxidase (HRPO)-based colorimetric assay to detect H2O2, glucose oxidase (GO; 12 mU/ml) produced 95 microM of H2O2 in 1 h, whereas only 46 microM of hydrogen peroxide accumulated in the presence of SV40-transformed human fibroblasts ( approximately 1 x 10(6). DNA damage was assessed in the mitochondira and three nuclear regions using a quantitative PCR assay. GO (12 mU/ml) resulted in more damage to the mitochondrial DNA (2.250 +/- 0.045 lesions/10 kb) than in any one of three nuclear targets, which included the non-expressed beta-globin locus (0.436 +/- 0.029 lesions/10 kb); and the active DNA polymerase b gene (0.442 +/- 0.037 lesions/10 kb); and the active hprt gene (0.310 +/- 0.025). Damage to the mtDNA occurred within 15 min of GO treatment, whereas nuclear damage did not appear until after 30 min, and reached a maximum after 60 min. Repair of mitochondrial damage after a 15 min GO (6 mU/ml) treatment was examined. Mitochondria repaired 50% of the damage after 1 h, and by 6 h all the damage was repaired. Higher doses of GO-generated H202, or more extended treatment periods, lead to mitochondrial DNA damage which was not repaired. Mitochondrial function was monitored using the MTT (3,(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay. A 15 min treatment with 6 mU/ml of GO decreased mitochondrial activity to 80% of the control; the activity recovered completely within 1 h after damage. These data show that GO-generated H202 causes acute damage to mtDNA and function, and demonstrate that this organelle is an important site for the cellular toxicity of ROS.

When it is too hot for photosynthesis: heat-induced instability of photosynthesis in relation to respiratory burst, cell permeability changes and H₂O₂ formation.

PubMed

Hüve, Katja; Bichele, Irina; Rasulov, Bahtijor; Niinemets, Ulo

2011-01-01

Photosynthesis rate (A(n)) becomes unstable above a threshold temperature, and the recovery upon return to low temperature varies because of reasons not fully understood. We investigated responses of A(n), dark respiration and chlorophyll fluorescence to supraoptimal temperatures of varying duration and kinetics in Phaseolus vulgaris asking whether the instability of photosynthesis under severe heat stress is associated with cellular damage. Cellular damage was assessed by Evans blue penetration (enhanced membrane permeability) and by H₂O₂ generation [3,3'-diaminobenzidine 4HCl (DAB)-staining]. Critical temperature for dark fluorescence (F(0) ) rise (T(F)) was at 46-48 °C, and a burst of respiration was observed near T(F). However, A(n) was strongly inhibited already before T(F) was reached. Membrane permeability increased with temperature according to a switch-type response, with enhanced permeability observed above 48 °C. Experiments with varying heat pulse lengths and intensities underscored the threshold-type loss of photosynthetic function, and indicated that the degree of photosynthetic deterioration and cellular damage depended on accumulated heat-dose. Beyond the 'point of no return', propagation of cellular damage and reduction of photosynthesis continued upon transfer to lower temperatures and photosynthetic recovery was slow or absent. We conclude that instability of photosynthesis under severe heat stress is associated with time-dependent propagation of cellular lesions. © 2010 Blackwell Publishing Ltd.

Investigating the role of melanin in UVA/UVB- and hydrogen peroxide-induced cellular and mitochondrial ROS production and mitochondrial DNA damage in human melanoma cells.

PubMed

Swalwell, Helen; Latimer, Jennifer; Haywood, Rachel M; Birch-Machin, Mark A

2012-02-01

Skin cancer incidence is dramatically increasing worldwide, with exposure to ultraviolet radiation (UVR) a predominant factor. The UVA component initiates oxidative stress in human skin, although its exact role in the initiation of skin cancer, particularly malignant melanoma, remains unclear and is controversial because there is evidence for a melanin-dependent mechanism in UVA-linked melanoma studies. Nonpigmented (CHL-1, A375), moderately pigmented (FM55, SKmel23), and highly pigmented (FM94, hyperpigmented FM55) human melanoma cell lines have been used to investigate UVA-induced production of reactive oxygen species using FACS analysis, at both the cellular (dihydrorhodamine-123) and the mitochondrial (MitoSOX) level, where most cellular stress is generated. For the first time, downstream mtDNA damage (utilizing a quantitative long-PCR assay) has been investigated. Using UVA, UVB, and H(2)O(2) as cellular stressors, we have explored the dual roles of melanin as a photoprotector and photosensitizer. The presence of melanin has no influence over cellular oxidative stress generation, whereas, in contrast, melanin protects against mitochondrial superoxide generation and mtDNA damage (one-way ANOVA with post hoc Tukey's analysis, P<0.001). We show that if melanin binds directly to DNA, it acts as a direct photosensitizer of mtDNA damage during UVA irradiation (P<0.001), providing evidence for the dual roles of melanin. Copyright © 2011 Elsevier Inc. All rights reserved.

Cellular responses to environmental DNA damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This volume contains the proceedings of the conference entitled Cellular Responses to Environmental DNA Damage held in Banff,Alberta December 1--6, 1991. The conference addresses various aspects of DNA repair in sessions titled DNA repair; Basic Mechanisms; Lesions; Systems; Inducible Responses; Mutagenesis; Human Population Response Heterogeneity; Intragenomic DNA Repair Heterogeneity; DNA Repair Gene Cloning; Aging; Human Genetic Disease; and Carcinogenesis. Individual papers are represented as abstracts of about one page in length.

The 8-oxoguanine DNA glycosylase 1 (ogg1) decreases the vulnerability of the developing brain to DNA damage.

PubMed

Gu, Aihua; Ji, Guixiang; Yan, Lifeng; Zhou, Yong

2013-12-01

The developing brain is particularly vulnerable to oxidative DNA damage, which may be the cause of most major congenital mental anomalies. The repair enzyme ogg1 initiates the highly conserved base-excision repair pathway. However, its function in the embryonic brain is largely unknown. This study is the first to validate the function of ogg1 during brain development using zebrafish embryos. Ogg1 was found to be highly expressed in the brain throughout early embryonic development, with particularly enrichment observed in the midbrain. The lack of ogg1 causes severe brain defects including changes in brain volume and integrity, destruction of the midbrain-hindbrain boundary, and balance and motor impairment, while overexpression of ogg1 can partially rescue these defects. Multiple cellular and molecular events were involved in the manifestation of brain defects due primarily to the lack of ogg1. These included (1) increased apoptosis; (2) decreased proliferation; and (3) aberrant axon distribution and extension from the inner surface towards the outer layers. The results of a microarray analysis showed that the expression of genes involved in cell cycle checkpoint, apoptosis, and neurogenesis were significantly changed in response to ogg1 knockdown. Cmyb was the key downstream gene that responses to DNA damage caused by ogg1 deficiency. Notably, the recruitment of ogg1 mRNA can alleviate the effects on the brain due to neural DNA damage. In summary, we introduce here that ogg1 is fundamentally required for protecting the developing brain, which may be helpful in understanding the aetiology of congenital brain deficits. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparing the effects of mitochondrial targeted and localized antioxidants with cellular antioxidants in human skin cells exposed to UVA and hydrogen peroxide.

PubMed

Oyewole, Anne O; Wilmot, Marie-Claire; Fowler, Mark; Birch-Machin, Mark A

2014-01-01

Skin cancer and aging are linked to increased cellular reactive oxygen species (ROS), particularly following exposure to ultraviolet A (UVA) in sunlight. As mitochondria are the main source of cellular ROS, this study compared the protective effects of mitochondria-targeted and -localized antioxidants (MitoQ and tiron, respectively) with cellular antioxidants against oxidative stress-induced [UVA and hydrogen peroxide (H2O2)] mitochondrial DNA (mtDNA) damage in human dermal fibroblasts. With the use of a long quantitative PCR assay, tiron (EC50 10 mM) was found to confer complete (100%) protection (P<0.001) against both UVA- and H2O2-induced mtDNA damage, whereas MitoQ (EC50 750 nM) provided less protection (17 and 32%, respectively; P<0.05). This particular protective effect of tiron was greater than a range of cellular antioxidants investigated. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway provides cellular protection against oxidative stress. An ELISA assay for the Nrf2 target gene heme oxygenase-1 (HO-1) and studies using Nrf2 small interfering RNA both indicated that tiron's mode of action was Nrf2 independent. The comet assay showed that tiron's protective effect against H2O2-induced nuclear DNA damage was greater than the cellular antioxidants and MitoQ (P<0.001). This study provides a platform to investigate molecules with similar structure to tiron as potent and clinically relevant antioxidants.

Contrasting effects of linaclotide and lubiprostone on restitution of epithelial cell barrier properties and cellular homeostasis after exposure to cell stressors

PubMed Central

2012-01-01

Background Linaclotide has been proposed as a treatment for the same gastrointestinal indications for which lubiprostone has been approved, chronic idiopathic constipation and irritable bowel syndrome with constipation. Stressors damage the epithelial cell barrier and cellular homeostasis leading to loss of these functions. Effects of active linaclotide on repair of barrier and cell function in pig jejunum after ischemia and in T84 cells after treatment with proinflammatory cytokines, interferon-γ and tumor necrosis factor-α were examined. Comparison with effects of lubiprostone, known to promote repair of barrier function was carried out. Results In ischemia-damaged pig jejunum, using measurements of transepithelial resistance, 3H-mannitol fluxes, short-circuit current (Cl− secretion) and occludin localization, active linaclotide failed to effectively promote repair of the epithelial barrier or recovery of short-circuit current, whereas lubiprostone promoted barrier repair and increased short-circuit current. In control pig jejunum, 1 μM linaclotide and 1 μM lubiprostone both caused similar increases in short-circuit current (Cl− secretion). In T84 cells, using measurements of transepithelial resistance, fluxes of fluorescent macromolecules, occludin and mitochondrial membrane potential, active linaclotide was virtually ineffective against damage caused by interferon-γ and tumor necrosis factor-α, while lubiprostone protected or promoted repair of epithelial barrier and cell function. Barrier protection/repair by lubiprostone was inhibited by methadone, a ClC-2 inhibitor. Linaclotide, but not lubiprostone increased [cGMP]i as expected and [Ca2+]i and linaclotide depolarized while lubiprostone hyperpolarized the T84 plasma membrane potential suggesting that lubiprostone may lead to greater cellular stability compared to linaclotide. In T84 cells, as found with linaclotide but not with lubiprostone, transepithelial resistance was slightly but significantly decreased by guanylin, STa and 8-bromo cGMP and fluorescent dextran fluxes were increased by guanylin. However the physiological implications of these small but statistically significant changes remain unclear. Conclusions Considering the physiological importance of epithelial barrier function and cell integrity and the known impact of stressors, the finding that lubiprostone, but not active linaclotide, exhibits the additional distinct property of effective protection or repair of the epithelial barrier and cell function after stress suggests potential clinical importance for patients with impaired or compromised barrier function such as might occur in IBS. PMID:22553939

Contrasting effects of linaclotide and lubiprostone on restitution of epithelial cell barrier properties and cellular homeostasis after exposure to cell stressors.

PubMed

Cuppoletti, John; Blikslager, Anthony T; Chakrabarti, Jayati; Nighot, Prashant K; Malinowska, Danuta H

2012-05-03

Linaclotide has been proposed as a treatment for the same gastrointestinal indications for which lubiprostone has been approved, chronic idiopathic constipation and irritable bowel syndrome with constipation. Stressors damage the epithelial cell barrier and cellular homeostasis leading to loss of these functions. Effects of active linaclotide on repair of barrier and cell function in pig jejunum after ischemia and in T84 cells after treatment with proinflammatory cytokines, interferon-γ and tumor necrosis factor-α were examined. Comparison with effects of lubiprostone, known to promote repair of barrier function was carried out. In ischemia-damaged pig jejunum, using measurements of transepithelial resistance, (3)H-mannitol fluxes, short-circuit current (Cl(-) secretion) and occludin localization, active linaclotide failed to effectively promote repair of the epithelial barrier or recovery of short-circuit current, whereas lubiprostone promoted barrier repair and increased short-circuit current. In control pig jejunum, 1 μM linaclotide and 1 μM lubiprostone both caused similar increases in short-circuit current (Cl(-) secretion). In T84 cells, using measurements of transepithelial resistance, fluxes of fluorescent macromolecules, occludin and mitochondrial membrane potential, active linaclotide was virtually ineffective against damage caused by interferon-γ and tumor necrosis factor-α, while lubiprostone protected or promoted repair of epithelial barrier and cell function. Barrier protection/repair by lubiprostone was inhibited by methadone, a ClC-2 inhibitor. Linaclotide, but not lubiprostone increased [cGMP]i as expected and [Ca(2+)]i and linaclotide depolarized while lubiprostone hyperpolarized the T84 plasma membrane potential suggesting that lubiprostone may lead to greater cellular stability compared to linaclotide. In T84 cells, as found with linaclotide but not with lubiprostone, transepithelial resistance was slightly but significantly decreased by guanylin, STa and 8-bromo cGMP and fluorescent dextran fluxes were increased by guanylin. However the physiological implications of these small but statistically significant changes remain unclear. Considering the physiological importance of epithelial barrier function and cell integrity and the known impact of stressors, the finding that lubiprostone, but not active linaclotide, exhibits the additional distinct property of effective protection or repair of the epithelial barrier and cell function after stress suggests potential clinical importance for patients with impaired or compromised barrier function such as might occur in IBS.

Effects of metabolic modifiers such as carnitines, coenzyme Q10, and PUFAs against different forms of neurotoxic insults: metabolic inhibitors, MPTP, and methamphetamine.

PubMed

Virmani, Ashraf; Gaetani, Franco; Binienda, Zbigniew

2005-08-01

A number of strategies using the nutritional approach are emerging for the protection of the brain from damage caused by metabolic toxins, age, or disease. Neural dysfunction and metabolic imbalances underlie many diseases, and the inclusion of metabolic modifiers may provide an alternative and early intervention approach that may prevent further damage. Various models have been developed to study the impact of metabolism on brain function. These have also proven useful in expanding our understanding of neurodegeneration processes. For example, the metabolic compromise induced by inhibitors such as 3-nitropropionic acid (3-NPA), rotenone, and 1-methyl-4-phenylpyridinium (MPP+) can cause neurodegeneration in animal models and these models are thought to simulate the processes that may lead to diseases such as Huntington's and Parkinson's diseases. These inhibitors of metabolism are thought to selectively kill neurons by inhibiting various mitochondrial enzymes. However, the eventual cell death is attributed to oxidative stress damage of selectively vulnerable cells, especially highly differentiated neurons. Various studies indicate that the neurotoxicity resulting from these types of metabolic compromise is related to mitochondrial dysfunction and may be ameliorated by metabolic modifiers such as L-carnitine (L-C), creatine, and coenzyme Q10, as well as by antioxidants such as lipoic acid, vitamin E, and resveratrol. Mitochondrial function and cellular metabolism are also affected by the dietary intake of essential polyunsaturated fatty acids (PUFAs), which may regulate membrane composition and influence cellular processes, especially the inflammatory pathways. Cellular metabolic function may also be ameliorated by caloric restriction diets. L-C is a naturally occurring quaternary ammonium compound that is a vital cofactor for the mitochondrial entry and oxidation of fatty acids. Any factors affecting L-C levels may also affect ATP levels. This endogenous compound, L-C, together with its acetyl ester, acetyl-L-carnitine (ALC), also participates in the control of the mitochondrial acyl-CoA/CoA ratio, peroxisomal oxidation of fatty acids, and production of ketone bodies. A deficiency of carnitine is known to have major deleterious effects on the CNS. We have examined L-C and its acetylated derivative, ALC, as potential neuroprotective compounds using various known metabolic inhibitors, as well as against drugs of abuse such as methamphetamine.

Honeybee society destruction by losing control of self-reproduction

NASA Astrophysics Data System (ADS)

Zhang, Peipei; Su, Beibei; He, Da-Ren

2004-03-01

Recently the mechanism of the damage caused by invasion of Apis mellifera capensis honeybee into the normal A. M. Scutellata colonies became interesting for scientists due to the fact that the mechanism may resemble those of cancer vicious hyperplasia, spreading of some epidemic, and turbulence of society induced by some bad society groups. For the mechanism, we suggest a new guess, which means that the losing control of self-reproduction disturbs and throws information structure of the society into confuse. We also simulate the damage process with a cellular automata based on the idea. The simulation shows that the process is equivalent to a non-equilibrium percolation phase transition. This discussion remind us that the management and monitor on the information network between society members may be a more effective way for avoiding the overflow of the destructor sub-colonies.

Protective effects of lactoferrin against intestinal mucosal damage induced by lipopolysaccharide in human intestinal Caco-2 cells.

PubMed

Hirotani, Yoshihiko; Ikeda, Kenji; Kato, Ryuji; Myotoku, Michiaki; Umeda, Takashi; Ijiri, Yoshio; Tanaka, Kazuhiko

2008-09-01

Indirect evidence suggests that lactoferrin (Lf), a major iron-binding protein in human milk, induces enterocyte growth and proliferation, depending on its concentration and affects the function and permeability of the intestinal mucosa. The bacterial endotoxin (lipopolysaccharide, LPS) is known to cause mucosal hyperpermeability in vivo. However, protective effects of Lf against LPS-mediated intestinal mucosal damage and barrier function in epithelial cells are not yet fully clarified. The aim of this study was to investigate whether Lf can reduce the cellular injury and alter epithelial hyperpermeability caused by LPS in human intestinal Caco-2 cells. When cell viability was measured by a WST-1 assay (tetrazolium salt-based assay), the protective effects against LPS-induced damage to Caco-2 cells were observed at doses of 800 and 1000 microg/ml Lf. The barrier function of Caco-2 monolayer tight junctions was assessed by measuring transepithelial electrical resistance (TEER) and permeability of FITC-labeled dextran 4000 (FD-4). The treatment of Caco-2 cells with Lf at doses of 400 and 1000 microg/ml significantly increased TEER as compared to treatment with LPS alone for 2 h (p<0.05). Further, at doses of 400 and 1000 microg/ml, Lf inhibited the enhancement of LPS-mediated permeability in Caco-2 cell monolayer. The results of this study suggest that Lf may have protective effects against LPS-mediated intestinal mucosal damage and impairment of barrier function in intestinal epithelial cells.

GPCR-autoantibodies in chronic heart failure.

PubMed

Boivin-Jahns, Valerie; Jahns, Roland

2018-06-01

Chronic heart failure (CHF) is a syndrome characterized by shortness of breath, fluid retention, and a progressive reduction in cardiac function. More than 60% of the cases are ischemic in origin (i.e., due to myo-cardial infarction) and about 30% are caused by non-ischemic myocardial damage (i.e., due to genetic or non-genetic causes like myocardial inflammation). Because of alterations in both cellular and humoral immunity patients with non-ischemic CHF often develop abnormal or misled immune responses, including cross-reacting antibodies and/or autoantibodies to various cardiac anti-gens. Non-ischemic myo-cardial damage was found to progress to CHF particularly, when associated (a) with the generation of autoantibodies directed against distinct myocyte membrane proteins critically involved in cardiac function - like G-protein coup-led membrane receptors (GPCRs), or (b) with virus persistence in the myocardium. This article will review current knowledge on the pathophysiological relevance of GPCR-autoreactivity in CHF by giving an overview on the so far available evidence from pre-clinical, clinical and epidemiological studies on the CHF-inducing potential of GPCR-autoantibodies and thereon based novel therapeutic approaches in GPCR autoantibody-associated CHF.

Thermosensitive hydrogel made of ferulic acid-gelatin and chitosan glycerophosphate.

PubMed

Cheng, Yung-Hsin; Yang, Shu-Hua; Liu, Chia-Ching; Gefen, Amit; Lin, Feng-Huei

2013-02-15

Reactive oxygen species-induced oxidative stress is involved in apoptosis of nucleus pulposus (NP) cells that can alter cellular phenotype and accelerate disc degeneration. Ferulic acid (FA) possesses an excellent antioxidant and anti-inflammatory properties. In the study, we developed the thermosensitive FA-gelatin/chitosan/glycerol phosphate (FA-G/C/GP) hydrogel which was applied as a sustained release system of FA to treat NP cells from the damage caused by oxidative stress. The gelation temperature of the FA-G/C/GP hydrogel was 32.17 °C. NP cells submitted to oxidative stress promoted by H(2)O(2), and post-treated with FA-G/C/GP exhibited down-regulation of MMP-3 and up-regulation aggrecan and type II collagen in mRNA level. The sulfated-glycosaminoglycan production was increased and the apoptosis was inhibited in the post-treatment group. The results suggest that the thermosensitive FA-G/C/GP hydrogel can treat NP cells from the damage caused by oxidative stress and may apply in minimally invasive surgery for NP regeneration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Kinetic theory approach to modeling of cellular repair mechanisms under genome stress.

PubMed

Qi, Jinpeng; Ding, Yongsheng; Zhu, Ying; Wu, Yizhi

2011-01-01

Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR) by using mathematical framework of kinetic theory of active particles (KTAP). Firstly, we focus on illustrating the profile of Cellular Repair System (CRS) instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances.

Dynamin-Related Protein 1 and Mitochondrial Fragmentation in Neurodegenerative Diseases

PubMed Central

Reddy, P. Hemachandra; Reddy, Tejaswini P.; Manczak, Maria; Calkins, Marcus J.; Shirendeb, Ulziibat; Mao, Peizhong

2010-01-01

The purpose of this article is to review the recent developments of abnormal mitochondrial dynamics, mitochondrial fragmentation, and neuronal damage in neurodegenerative diseases, including Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis. The GTPase family of proteins, including fission proteins, dynamin related protein 1 (Drp1), mitochondrial fission 1 (Fis1), and fusion proteins (Mfn1, Mfn2 and Opa1) are essential to maintain mitochondrial fission and fusion balance, and to provide necessary adenosine triphosphate to neurons. Among these, Drp1 is involved in several important aspects of mitochondria, including shape, size, distribution, remodeling, and maintenance of X in mammalian cells. In addition, recent advancements in molecular, cellular, electron microscopy, and confocal imaging studies revealed that Drp1 is associated with several cellular functions, including mitochondrial and peroxisomal fragmentation, phosphorylation, SUMOylation, ubiquitination, and cell death. In the last two decades, tremendous progress has been made in researching mitochondrial dynamics, in yeast, worms, and mammalian cells; and this research has provided evidence linking Drp1 to neurodegenerative diseases. Researchers in the neurodegenerative disease field are beginning to recognize the possible involvement of Drp1 in causing mitochondrial fragmentation and abnormal mitochondrial dynamics in neurodegenerative diseases. This article summarizes research findings relating Drp1 to mitochondrial fission and fusion, in yeast, worms, and mammals. Based on findings from the Reddy laboratory and others’, we propose that mutant proteins of neurodegenerative diseases, including AD, PD, HD, and ALS, interact with Drp1, activate mitochondrial fission machinery, fragment mitochondria excessively, and impair mitochondrial transport and mitochondrial dynamics, ultimately causing mitochondrial dysfunction and neuronal damage. PMID:21145355

Comparison of responses of salivary antioxidant markers to exhaustive aerobic exercise in smoker and non-smoker young girls.

PubMed

Arazi, Hamid; Simaei, Esmat; Taati, Behzad

2016-10-01

Smoking is known as a serious global public health problem, and is also an important risk factor for oral diseases and cause of oxidative stress and cellular damage. Saliva is the first biological medium encountered during inhalation of cigarette smoke. Additionally, previous studies demonstrated that exhaustive aerobic exercise could increase oxidative stress and cellular damage. Therefore, the main aim of this study was to compare the response of salivary antioxidants (peroxides (POX), uric acid (UA), 1-1dipheny l-2-picrylhydrazyl hydrate (DPPH) of exhaustive aerobic exercise between healthy smoker and non-smoker young girls. Ten smokers and 10 non-smokers were enrolled for this study. Subjects performed a progressive cycle ergometer with an initial load of 50 W that was increased 50Wevery 3 minutes at the speed of 60rpm, until exhaustion. Un-stimulated saliva samples were collected before, immediately and 1 hour after exercise. The results showed that POX activity and UA concentration significantly increased immediately after exercise in both groups when compared to the pre exercise values (P<0.01). The level of salivary POX of non-smokers were greater than smokers immediately after exercise (P<0.01). Aerobic exercise caused a decrease in salivary DPPH activity immediately and 1 h after exercise in both groups (P<0.01). When the DPPH values were compared between smoker and non-smoker subjects, a significant decrease was observed in smokers immediately and 1 h after exercise (P<0.01). In conclusion, aerobic exercise was induced oxidative stress in both groups but oxidative stress in smoking females was greater.

Chk1 Promotes DNA Damage Response Bypass following Oxidative Stress in a Model of Hydrogen Peroxide-Associated Ulcerative Colitis through JNK Inactivation and Chromatin Binding

PubMed Central

Silver, Andrew; Guenther, Thomas; Siedentopf, Sandra; Ross, Jochen; Vo, Diep-Khanh; Roessner, Albert

2017-01-01

Dysregulation of c-Jun N-terminal kinase (JNK) activation promoted DNA damage response bypass and tumorigenesis in our model of hydrogen peroxide-associated ulcerative colitis (UC) and in patients with quiescent UC (QUC), UC-related dysplasia, and UC-related carcinoma (UC-CRC), thereby adapting to oxidative stress. In the UC model, we have observed features of oncogenic transformation: increased proliferation, undetected DNA damage, and apoptosis resistance. Here, we show that Chk1 was downregulated but activated in the acute and quiescent chronic phases. In both phases, Chk1 was linked to DNA damage response bypass by suppressing JNK activation following oxidative stress, promoting cell cycle progression despite DNA damage. Simultaneously, activated Chk1 was bound to chromatin. This triggered histone acetylation and the binding of histone acetyltransferases and transcription factors to chromatin. Thus, chromatin-immobilized activated Chk1 executed a dual function by suppressing DNA damage response and simultaneously inducing chromatin modulation. This caused undetected DNA damage and increased cellular proliferation through failure to transmit the appropriate DNA damage signal. Findings in vitro were corroborated by chromatin accumulation of activated Chk1, Ac-H3, Ac-H4, and c-Jun in active UC (AUC) in vivo. Targeting chromatin-bound Chk1, GCN5, PCAF, and p300/CBP could be a novel therapeutic strategy to prevent UC-related tumor progression. PMID:28751935

Activation of WIP1 Phosphatase by HTLV-1 Tax Mitigates the Cellular Response to DNA Damage

PubMed Central

Dayaram, Tajhal; Lemoine, Francene J.; Donehower, Lawrence A.; Marriott, Susan J.

2013-01-01

Genomic instability stemming from dysregulation of cell cycle checkpoints and DNA damage response (DDR) is a common feature of many cancers. The cancer adult T cell leukemia (ATL) can occur in individuals infected with human T cell leukemia virus type 1 (HTLV-1), and ATL cells contain extensive chromosomal abnormalities, suggesting that they have defects in the recognition or repair of DNA damage. Since Tax is the transforming protein encoded by HTLV-1, we asked whether Tax can affect cell cycle checkpoints and the DDR. Using a combination of flow cytometry and DNA repair assays we showed that Tax-expressing cells exit G1 phase and initiate DNA replication prematurely following damage. Reduced phosphorylation of H2AX (γH2AX) and RPA2, phosphoproteins that are essential to properly initiate the DDR, was also observed in Tax-expressing cells. To determine the cause of decreased DDR protein phosphorylation in Tax-expressing cells, we examined the cellular phosphatase, WIP1, which is known to dephosphorylate γH2AX. We found that Tax can interact with Wip1 in vivo and in vitro, and that Tax-expressing cells display elevated levels of Wip1 mRNA. In vitro phosphatase assays showed that Tax can enhance Wip1 activity on a γH2AX peptide target by 2-fold. Thus, loss of γH2AX in vivo could be due, in part, to increased expression and activity of WIP1 in the presence of Tax. siRNA knockdown of WIP1 in Tax-expressing cells rescued γH2AX in response to damage, confirming the role of WIP1 in the DDR. These studies demonstrate that Tax can disengage the G1/S checkpoint by enhancing WIP1 activity, resulting in reduced DDR. Premature G1 exit of Tax-expressing cells in the presence of DNA lesions creates an environment that tolerates incorporation of random mutations into the host genome. PMID:23405243

Fibroblast growth factor 2 protects against renal ischaemia/reperfusion injury by attenuating mitochondrial damage and proinflammatory signalling.

PubMed

Tan, Xiao-Hua; Zheng, Xiao-Meng; Yu, Li-Xia; He, Jian; Zhu, Hong-Mei; Ge, Xiu-Ping; Ren, Xiao-Li; Ye, Fa-Qing; Bellusci, Saverio; Xiao, Jian; Li, Xiao-Kun; Zhang, Jin-San

2017-11-01

Ischaemia-reperfusion injury (I/RI) is a common cause of acute kidney injury (AKI). The molecular basis underlying I/RI-induced renal pathogenesis and measures to prevent or reverse this pathologic process remains to be resolved. Basic fibroblast growth factor (FGF2) is reported to have protective roles of myocardial infarction as well as in several other I/R related disorders. Herein we present evidence that FGF2 exhibits robust protective effect against renal histological and functional damages in a rat I/RI model. FGF2 treatment greatly alleviated I/R-induced acute renal dysfunction and largely blunted I/R-induced elevation in serum creatinine and blood urea nitrogen, and also the number of TUNEL-positive tubular cells in the kidney. Mechanistically, FGF2 substantially ameliorated renal I/RI by mitigating several mitochondria damaging parameters including pro-apoptotic alteration of Bcl2/Bax expression, caspase-3 activation, loss of mitochondrial membrane potential and K ATP channel integrity. Of note, the protective effect of FGF2 was significantly compromised by the K ATP channel blocker 5-HD. Interestingly, I/RI alone resulted in mild activation of FGFR, whereas FGF2 treatment led to more robust receptor activation. More significantly, post-I/RI administration of FGF2 also exhibited robust protection against I/RI by reducing cell apoptosis, inhibiting the release of damage-associated molecular pattern molecule HMBG1 and activation of its downstream inflammatory cytokines such as IL-1α, IL-6 and TNF α. Taken together, our data suggest that FGF2 offers effective protection against I/RI and improves animal survival by attenuating mitochondrial damage and HMGB1-mediated inflammatory response. Therefore, FGF2 has the potential to be used for the prevention and treatment of I/RI-induced AKI. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Autophagy protects gastric mucosal epithelial cells from ethanol-induced oxidative damage via mTOR signaling pathway

PubMed Central

Chang, Weilong; Bai, Jie; Tian, Shaobo; Ma, Muyuan; Li, Wei; Yin, Yuping; Deng, Rui; Cui, Jinyuan; Li, Jinjin; Wang, Guobin; Tao, Kaixiong

2017-01-01

Alcohol abuse is an important cause of gastric mucosal epithelial cell injury and gastric ulcers. A number of studies have demonstrated that autophagy, an evolutionarily conserved cellular mechanism, has a protective effect on cell survival. However, it is not known whether autophagy can protect gastric mucosal epithelial cells against the toxic effects of ethanol. In the present study, gastric mucosal epithelial cells (GES-1 cells) and Wistar rats were treated with ethanol to detect the adaptive response of autophagy. Our results demonstrated that ethanol exposure induced gastric mucosal epithelial cell damage, which was accompanied by the downregulation of mTOR signaling pathway and activation of autophagy. Suppression of autophagy with pharmacological agents resulted in a significant increase of GES-1 cell apoptosis and gastric mucosa injury, suggesting that autophagy could protect cells from ethanol toxicity. Furthermore, we evaluated the cellular oxidative stress response following ethanol treatment and found that autophagy induced by ethanol inhibited generation of reactive oxygen species and degradation of antioxidant and lipid peroxidation. In conclusion, these findings provide evidence that ethanol can activate autophagy via downregulation of the mTOR signaling pathway, serving as an adaptive mechanism to ameliorate oxidative damage induced by ethanol in gastric mucosal epithelial cells. Therefore, modifying autophagy may provide a therapeutic strategy against alcoholic gastric mucosa injury. Impact statement The effect and mechanism of autophagy on ethanol-induced cell damage remain controversial. In this manuscript, we report the results of our study demonstrating that autophagy can protect gastric mucosal epithelial cells against ethanol toxicity in vitro and in vivo. We have shown that ethanol can activate autophagy via downregulation of the mTOR signaling pathway, serving as an adaptive mechanism to ameliorate ethanol-induced oxidative damage in gastric mucosal epithelial cells. This study brings new and important insights into the mechanism of alcoholic gastric mucosal injury and may provide an avenue for future therapeutic strategies. PMID:28056554

Chronic administration of thiamine pyrophosphate decreases age-related histological atrophic testicular changes and improves sexual behavior in male Wistar rats.

PubMed

Hernández-Montiel, H L; Vásquez López, C M; González-Loyola, J G; Vega-Anaya, G C; Villagrán-Herrera, M E; Gallegos-Corona, M A; Saldaña, C; Ramos Gómez, M; García Horshman, P; García Solís, P; Solís-S, J C; Robles-Osorio, M L; Ávila Morales, J; Varela-Echavarría, A; Paredes Guerrero, R

2014-06-01

Aging is a multifactorial universal process and constitutes the most important risk factor for chronic-degenerative diseases. Although it is a natural process, pathological aging arises when these changes occur quickly and the body is not able to adapt. This is often associated with the generation of reactive oxygen species (ROS), inflammation, and a decrease in the endogenous antioxidant systems, constituting a physiopathological state commonly found in chronic-degenerative diseases. At the testicular level, aging is associated with tissue atrophy, decreased steroidogenesis and spermatogenesis, and sexual behavior disorders. This situation, in addition to the elevated generation of ROS in the testicular steroidogenesis, provides a critical cellular environment causing oxidative damage at diverse cellular levels. To assess the effects of a reduction in the levels of ROS, thiamine pyrophosphate (TPP) was chronically administered in senile Wistar rats. TPP causes an activation of intermediate metabolism routes, enhancing cellular respiration and decreasing the generation of ROS. Our results show an overall decrease of atrophic histological changes linked to aging, with higher levels of serum testosterone, sexual activity, and an increase in the levels of endogenous antioxidant enzymes in TPP-treated animals. These results suggest that TPP chronic administration decreases the progression of age-related atrophic changes by improving the intermediate metabolism, and by increasing the levels of antioxidant enzymes.

Mitochondria targeting by environmental stressors: Implications for redox cellular signaling.

PubMed

Blajszczak, Chuck; Bonini, Marcelo G

2017-11-01

Mitochondria are cellular powerhouses as well as metabolic and signaling hubs regulating diverse cellular functions, from basic physiology to phenotypic fate determination. It is widely accepted that reactive oxygen species (ROS) generated in mitochondria participate in the regulation of cellular signaling, and that some mitochondria chronically operate at a high ROS baseline. However, it is not completely understood how mitochondria adapt to persistently high ROS states and to environmental stressors that disturb the redox balance. Here we will review some of the current concepts regarding how mitochondria resist oxidative damage, how they are replaced when excessive oxidative damage compromises function, and the effect of environmental toxicants (i.e. heavy metals) on the regulation of mitochondrial ROS (mtROS) production and subsequent impact. Copyright © 2017 Elsevier B.V. All rights reserved.

USP7S-dependent inactivation of Mule regulates DNA damage signalling and repair.

PubMed

Khoronenkova, Svetlana V; Dianov, Grigory L

2013-02-01

The E3 ubiquitin ligase Mule/ARF-BP1 plays an important role in the cellular DNA damage response by controlling base excision repair and p53 protein levels. However, how the activity of Mule is regulated in response to DNA damage is currently unknown. Here, we report that the Ser18-containing isoform of the USP7 deubiquitylation enzyme (USP7S) controls Mule stability by preventing its self-ubiquitylation and subsequent proteasomal degradation. We find that in response to DNA damage, downregulation of USP7S leads to self-ubiquitylation and proteasomal degradation of Mule, which eventually leads to p53 accumulation. Cells that are unable to downregulate Mule show reduced ability to upregulate p53 levels in response to DNA damage. We also find that, as Mule inactivation is required for stabilization of base excision repair enzymes, the failure of cells to downregulate Mule after DNA damage results in deficient DNA repair. Our data describe a novel mechanism by which Mule is regulated in response to DNA damage and coordinates cellular DNA damage responses and DNA repair.

Transforming growth factor-beta1 mediates cellular response to DNA damage in situ

NASA Technical Reports Server (NTRS)

Ewan, Kenneth B.; Henshall-Powell, Rhonda L.; Ravani, Shraddha A.; Pajares, Maria Jose; Arteaga, Carlos; Warters, Ray; Akhurst, Rosemary J.; Barcellos-Hoff, Mary Helen

2002-01-01

Transforming growth factor (TGF)-beta1 is rapidly activated after ionizing radiation, but its specific role in cellular responses to DNA damage is not known. Here we use Tgfbeta1 knockout mice to show that radiation-induced apoptotic response is TGF-beta1 dependent in the mammary epithelium, and that both apoptosis and inhibition of proliferation in response to DNA damage decrease as a function of TGF-beta1 gene dose in embryonic epithelial tissues. Because apoptosis in these tissues has been shown previously to be p53 dependent, we then examined p53 protein activation. TGF-beta1 depletion, by either gene knockout or by using TGF-beta neutralizing antibodies, resulted in decreased p53 Ser-18 phosphorylation in irradiated mammary gland. These data indicate that TGF-beta1 is essential for rapid p53-mediated cellular responses that mediate cell fate decisions in situ.

Oxidative Stress, Bone Marrow Failure, and Genome Instability in Hematopoietic Stem Cells

PubMed Central

Richardson, Christine; Yan, Shan; Vestal, C. Greer

2015-01-01

Reactive oxygen species (ROS) can be generated by defective endogenous reduction of oxygen by cellular enzymes or in the mitochondrial respiratory pathway, as well as by exogenous exposure to UV or environmental damaging agents. Regulation of intracellular ROS levels is critical since increases above normal concentrations lead to oxidative stress and DNA damage. A growing body of evidence indicates that the inability to regulate high levels of ROS leading to alteration of cellular homeostasis or defective repair of ROS-induced damage lies at the root of diseases characterized by both neurodegeneration and bone marrow failure as well as cancer. That these diseases may be reflective of the dynamic ability of cells to respond to ROS through developmental stages and aging lies in the similarities between phenotypes at the cellular level. This review summarizes work linking the ability to regulate intracellular ROS to the hematopoietic stem cell phenotype, aging, and disease. PMID:25622253

Oligodendroglia are particularly vulnerable to oxidative damage after neurotrauma in vivo.

PubMed

Giacci, Marcus K; Bartlett, Carole A; Smith, Nicole M; Iyer, K Swaminathan; Toomey, Lillian M; Jiang, Haibo; Guagliardo, Paul; Kilburn, Matt R; Fitzgerald, Melinda

2018-06-18

Loss of function following injury to the central nervous system is worsened by secondary degeneration of neurons and glia surrounding the injury and initiated by oxidative damage. However, it is not yet known which cellular populations and structures are most vulnerable to oxidative damage in vivo Using Nanoscale secondary ion mass spectrometry (NanoSIMS), oxidative damage was semi-quantified within cellular subpopulations and structures of optic nerve vulnerable to secondary degeneration, following a partial transection of the optic nerve in adult female PVG rats. Simultaneous assessment of cellular subpopulations and structures revealed oligodendroglia as the most vulnerable to DNA oxidation following injury. 5-ethynyl-2'-deoxyuridine (EdU) was used to label cells that proliferated in the first 3 days after injury. Injury led to increases in DNA, protein and lipid damage in OPCs and mature oligodendrocytes at 3 days, regardless of proliferative state, associated with a decline in the numbers of OPCs at 7 days. O4+ pre-oligodendrocytes also exhibited increased lipid peroxidation. Interestingly, EdU+ mature oligodendrocytes derived after injury demonstrated increased early susceptibility to DNA damage and lipid peroxidation. However, EdU- mature oligodendrocytes with high 8OHdG immunoreactivity were more likely to be caspase3+. By day 28, newly derived mature oligodendrocytes had significantly reduced MYRF mRNA indicating that the myelination potential of these cells may be reduced. The proportion of caspase3+ oligodendrocytes remained higher in EdU- cells. Innovative use of NanoSIMS together with traditional immunohistochemistry and in situ hybridisation have enabled the first demonstration of subpopulation specific oligodendroglial vulnerability to oxidative damage, due to secondary degeneration in vivo. SIGNIFICANCE STATEMENT Injury to the central nervous system is characterised by oxidative damage in areas adjacent to the injury. However, the cellular subpopulations and structures most vulnerable to this damage remain to be elucidated. Here we use powerful NanoSIMS techniques to show increased oxidative damage in oligodendroglia and axons and to demonstrate that cells early in the oligodendroglial lineage are the most vulnerable to DNA oxidation. Further immunohistochemical and in situ hybridisation investigation reveals that mature oligodendrocytes derived after injury are more vulnerable to oxidative damage than their counterparts existing at the time of injury and have reduced MYRF mRNA, yet pre-existing oligodendrocytes are more likely to die. Copyright © 2018 the authors.

Monoacylglycerol Lipases Act as Evolutionarily Conserved Regulators of Non-oxidative Ethanol Metabolism*

PubMed Central

Heier, Christoph; Taschler, Ulrike; Radulovic, Maja; Aschauer, Philip; Eichmann, Thomas O.; Grond, Susanne; Wolinski, Heimo; Oberer, Monika; Zechner, Rudolf; Kohlwein, Sepp D.; Zimmermann, Robert

2016-01-01

Fatty acid ethyl esters (FAEEs) are non-oxidative metabolites of ethanol that accumulate in human tissues upon ethanol intake. Although FAEEs are considered as toxic metabolites causing cellular dysfunction and tissue damage, the enzymology of FAEE metabolism remains poorly understood. In this study, we used a biochemical screen in Saccharomyces cerevisiae to identify and characterize putative hydrolases involved in FAEE catabolism. We found that Yju3p, the functional orthologue of mammalian monoacylglycerol lipase (MGL), contributes >90% of cellular FAEE hydrolase activity, and its loss leads to the accumulation of FAEE. Heterologous expression of mammalian MGL in yju3Δ mutants restored cellular FAEE hydrolase activity and FAEE catabolism. Moreover, overexpression or pharmacological inhibition of MGL in mouse AML-12 hepatocytes decreased or increased FAEE levels, respectively. FAEEs were transiently incorporated into lipid droplets (LDs) and both Yju3p and MGL co-localized with these organelles. We conclude that the storage of FAEE in inert LDs and their mobilization by LD-resident FAEE hydrolases facilitate a controlled metabolism of these potentially toxic lipid metabolites. PMID:27036938

Femtosecond laser nanosurgery of sub-cellular structures in HeLa cells by employing Third Harmonic Generation imaging modality as diagnostic tool.

PubMed

Tserevelakis, George J; Psycharakis, Stylianos; Resan, Bojan; Brunner, Felix; Gavgiotaki, Evagelia; Weingarten, Kurt; Filippidis, George

2012-02-01

Femtosecond laser assisted nanosurgery of microscopic biological specimens is a relatively new technique which allows the selective disruption of sub-cellular structures without causing any undesirable damage to the surrounding regions. The targeted structures have to be stained in order to be clearly visualized for the nanosurgery procedure. However, the validation of the final nanosurgery result is difficult, since the targeted structure could be simply photobleached rather than selectively destroyed. This fact comprises a main drawback of this technique. In our study we employed a multimodal system which integrates non-linear imaging modalities with nanosurgery capabilities, for the selective disruption of sub-cellular structures in HeLa cancer cells. Third Harmonic Generation (THG) imaging modality was used as a tool for the identification of structures that were subjected to nanosurgery experiments. No staining of the biological samples was required, since THG is an intrinsic property of matter. Furthermore, cells' viability after nanosurgery processing was verified via Two Photon Excitation Fluorescence (TPEF) measurements. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A selective USP1-UAF1 inhibitor links deubiquitination to DNA damage responses

PubMed Central

Liang, Qin; Dexheimer, Thomas S; Zhang, Ping; Rosenthal, Andrew S; Villamil, Mark A; You, Changjun; Zhang, Qiuting; Chen, Junjun; Ott, Christine A; Sun, Hongmao; Luci, Diane K; Yuan, Bifeng; Simeonov, Anton; Jadhav, Ajit; Xiao, Hui; Wang, Yinsheng; Maloney, David J; Zhuang, Zhihao

2014-01-01

Protein ubiquitination and deubiquitination are central to the control of a large number of cellular pathways and signaling networks in eukaryotes. Although the essential roles of ubiquitination have been established in the eukaryotic DNA damage response, the deubiquitination process remains poorly defined. Chemical probes that perturb the activity of deubiquitinases (DUBs) are needed to characterize the cellular function of deubiquitination. Here we report ML323 (2), a highly potent inhibitor of the USP1-UAF1 deubiquitinase complex with excellent selectivity against human DUBs, deSUMOylase, deneddylase and unrelated proteases. Using ML323, we interrogated deubiquitination in the cellular response to UV- and cisplatin-induced DNA damage and revealed new insights into the requirement of deubiquitination in the DNA translesion synthesis and Fanconi anemia pathways. Moreover, ML323 potentiates cisplatin cytotoxicity in non-small cell lung cancer and osteosarcoma cells. Our findings point to USP1-UAF1 as a key regulator of the DNA damage response and a target for overcoming resistance to the platinum-based anticancer drugs. PMID:24531842

Reactive oxygen species mediated DNA damage in human lung alveolar epithelial (A549) cells from exposure to non-cytotoxic MFI-type zeolite nanoparticles.

PubMed

Bhattacharya, Kunal; Naha, Pratap C; Naydenova, Izabela; Mintova, Svetlana; Byrne, Hugh J

2012-12-17

Increasing utilization of engineered nanoparticles in the field of electronics and biomedical applications demands an assessment of risk associated with deliberate or accidental exposure. Metal based nanoparticles are potentially most important of all the nanoparticles in terms of health risks. Microporous alumino-silicates and pure silicates named as zeolites and zeo-type materials with variety of structures, chemical compositions, particle sizes and morphologies have a significant number of industrial uses such as in catalysis, sorption and ion-exchange processes. In particular, the nanosized particles due to their unique properties are used in hybrid organic-inorganic materials for photography, photonics, electronics, labeling, imaging, and sensing. The aim of the current study is to investigate pure silica MFI-type zeolites nanoparticles with sizes of 50nm and 100nm (samples MFI-50 and MFI-100) under suspended conditions and their toxicological effects on human lung alveolar (A549) cells under in vitro conditions. Live cell imaging showed that the nanoparticles precipitated from the colloidal suspension of cell culture media as large agglomerates, coming in contact with the cell surface through sedimentation. A cellular proliferative capacity test showed the zeolite nanoparticles to exhibit no significant cytotoxicity below a concentration of 100μg/ml. However, both the MFI-50 and MFI-100 nanoparticles induced high intracellular reactive oxygen species (ROS) generation and elevated mitochondrial membrane potential in the A549 cells over the measured time period of 12h and at concentrations up to ≤50μg/ml. DNA fragmentation analysis using the comet assay showed that the MFI-50 and MFI-100 nanoparticles cause genotoxicity in a concentration dependent manner. Furthermore, the rate at which maximum genomic damage was caused by MFI-100 nanoparticles in the A549 cells was found to be high as compared to the MFI-50 nanoparticles. However, the damage caused by the MFI-50 nanoparticles was found to accumulate over a longer period of time as compared to MFI-100 nanoparticles. The study therefore points towards the capability of the non-cytotoxic zeolite nanoparticles to induce oxidative stress resulting in short-term altered cellular metabolism up-regulation and genomic instability. Although the damage was found to be short-lived, its persistence over longer durations, or stabilization cannot be neglected. Further studies are in progress to yield a better understanding of the mechanisms for oxidative stress and resulting cascade of events leading to genetic damage in the human lung alveolar epithelial cells following exposure to zeolite nanoparticles of different sizes. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Radiation Effect on Human Tissue

NASA Technical Reports Server (NTRS)

Richmond, Robert C.; Cruz, Angela; Bors, Karen; Curreri, Peter A. (Technical Monitor)

2002-01-01

Predicting the occurrence of human cancer following exposure of an epidemiologic population to any agent causing genetic damage is a difficult task. To an approximation, this is because the uncertainty of uniform exposure to the damaging agent, and the uncertainty of uniform processing of that damage within a complex set of biological variables, degrade the confidence of predicting the delayed expression of cancer as a relatively rare event within clinically normal individuals. This situation begs the need for alternate controlled experimental models that are predictive for the development of human cancer following exposures to agents causing genetic damage. Such models historically have not been of substantial proven value. It is more recently encouraging, however, that developments in molecular and cell biology have led to an expanded knowledge of human carcinogenesis, and of molecular markers associated with that process. It is therefore appropriate to consider new laboratory models developed to accomodate that expanded knowledge in order to assess the cancer risks associated with exposures to genotoxic agents. When ionizing radiation of space is the genotoxic agent, then a series of additional considerations for human cancer risk assessment must also be applied. These include the dose of radiation absorbed by tissue at different locations in the body, the quality of the absorbed radiation, the rate at which absorbed dose accumulates in tissue, the way in which absorbed dose is measured and calculated, and the alterations in incident radiation caused by shielding materials. It is clear that human cancer risk assessment for damage caused by ionizing radiation is a multidisciplinary responsibility, and that within this responsibility no single discipline can hold disproportionate sway if a risk assessment model of radiation-induced human cancer is to be developed that has proven value. Biomolecular and cellular markers from the work reported here are considered for use in assessing human cancer risk related to exposure to space radiation. This potential use must be integrated within the specified multidisciplinary context in order to create a new tool of molecular epidemiology that can hopefully then realistically assess this cancer risk.

Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species.

PubMed

Leonard, Stephen S; Chen, Bean T; Stone, Samuel G; Schwegler-Berry, Diane; Kenyon, Allison J; Frazer, David; Antonini, James M

2010-11-03

Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Our results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of fume generated, particle size, and elapsed time after generation of the welding exposure are significant factors in radical generation and particle deposition these factors should be considered when developing protective strategies.

Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

PubMed Central

2010-01-01

Background Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Results Our results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Conclusion Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of fume generated, particle size, and elapsed time after generation of the welding exposure are significant factors in radical generation and particle deposition these factors should be considered when developing protective strategies. PMID:21047424

Evaluation of Ultrasound-Induced Damage to Escherichia coli and Staphylococcus aureus by Flow Cytometry and Transmission Electron Microscopy

PubMed Central

Li, Jiao; Ahn, Juhee; Liu, Donghong; Chen, Shiguo; Ye, Xingqian

2016-01-01

As a nonthermal sterilization technique, ultrasound has attracted great interest in the field of food preservation. In this study, flow cytometry and transmission electron microscopy were employed to investigate ultrasound-induced damage to Escherichia coli and Staphylococcus aureus. For flow cytometry studies, single staining with propidium iodide (PI) or carboxyfluorescein diacetate (cFDA) revealed that ultrasound treatment caused cell death by compromising membrane integrity, inactivating intracellular esterases, and inhibiting metabolic performance. The results showed that ultrasound damage was independent of initial bacterial concentrations, while the mechanism of cellular damage differed according to the bacterial species. For the Gram-negative bacterium E. coli, ultrasound worked first on the outer membrane rather than the cytoplasmic membrane. Based on the double-staining results, we inferred that ultrasound treatment might be an all-or-nothing process: cells ruptured and disintegrated by ultrasound cannot be revived, which can be considered an advantage of ultrasound over other nonthermal techniques. Transmission electron microscopy studies revealed that the mechanism of ultrasound-induced damage was multitarget inactivation, involving the cell wall, cytoplasmic membrane, and inner structure. Understanding of the irreversible antibacterial action of ultrasound has great significance for its further utilization in the food industry. PMID:26746712

Blood micronutrients and DNA damage in children.

PubMed

Milne, Elizabeth; Greenop, Kathryn R; Ramankutty, Padmaja; Miller, Margaret; de Klerk, Nicholas H; Armstrong, Bruce K; Almond, Theodora; O'Callaghan, Nathan J; Fenech, Michael

2015-10-01

Maintenance of normal cellular phenotype depends largely on accurate DNA replication and repair. DNA damage causes gene mutations and predisposes to cancer and other chronic diseases. Growing evidence indicates that nutritional factors are associated with DNA damage in adults; here, we investigate these associations in children. We conducted a cross-sectional study among 462 healthy children 3, 6, and 9 years of age. Blood was collected and micronutrient levels were measured. The cytokinesis-block micronucleus cytome assay was used to measure chromosomal DNA damage (micronuclei, nucleoplasmic bridges, and nuclear buds) in lymphocytes. Cell apoptosis, necrosis, and the nuclear division index were also measured. Nine loci in genes involved in folate metabolism and DNA repair were genotyped. Data were analyzed using linear regression with adjustment for potential confounders. Plasma calcium was positively associated with micronuclei and necrosis, and α-tocopherol negatively associated with apoptosis, nuclear division index, and nucleoplasmic bridges; lutein was positively associated with nucleoplasmic bridges. α-tocopherol was positively associated with necrosis. DNA damage in healthy children may be influenced by blood micronutrient levels and certain genotypes. Further investigation of associations between nutritional status and genomic integrity in children is needed to shed additional light on potential mechanisms. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DNA damage in the oligodendrocyte lineage and its role in brain aging.

PubMed

Tse, Kai-Hei; Herrup, Karl

2017-01-01

Myelination is a recent evolutionary addition that significantly enhances the speed of transmission in the neural network. Even slight defects in myelin integrity impair performance and enhance the risk of neurological disorders. Indeed, myelin degeneration is an early and well-recognized neuropathology that is age associated, but appears before cognitive decline. Myelin is only formed by fully differentiated oligodendrocytes, but the entire oligodendrocyte lineage are clear targets of the altered chemistry of the aging brain. As in neurons, unrepaired DNA damage accumulates in the postmitotic oligodendrocyte genome during normal aging, and indeed may be one of the upstream causes of cellular aging - a fact well illustrated by myelin co-morbidity in premature aging syndromes arising from deficits in DNA repair enzymes. The clinical and experimental evidence from Alzheimer's disease, progeroid syndromes, ataxia-telangiectasia and other conditions strongly suggest that oligodendrocytes may in fact be uniquely vulnerable to oxidative DNA damage. If this damage remains unrepaired, as is increasingly true in the aging brain, myelin gene transcription and oligodendrocyte differentiation is impaired. Delineating the relationships between early myelin loss and DNA damage in brain aging will offer an additional dimension outside the neurocentric view of neurodegenerative disease. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Modeling cognitive deficits following neurodegenerative diseases and traumatic brain injuries with deep convolutional neural networks.

PubMed

Lusch, Bethany; Weholt, Jake; Maia, Pedro D; Kutz, J Nathan

2018-06-01

The accurate diagnosis and assessment of neurodegenerative disease and traumatic brain injuries (TBI) remain open challenges. Both cause cognitive and functional deficits due to focal axonal swellings (FAS), but it is difficult to deliver a prognosis due to our limited ability to assess damaged neurons at a cellular level in vivo. We simulate the effects of neurodegenerative disease and TBI using convolutional neural networks (CNNs) as our model of cognition. We utilize biophysically relevant statistical data on FAS to damage the connections in CNNs in a functionally relevant way. We incorporate energy constraints on the brain by pruning the CNNs to be less over-engineered. Qualitatively, we demonstrate that damage leads to human-like mistakes. Our experiments also provide quantitative assessments of how accuracy is affected by various types and levels of damage. The deficit resulting from a fixed amount of damage greatly depends on which connections are randomly injured, providing intuition for why it is difficult to predict impairments. There is a large degree of subjectivity when it comes to interpreting cognitive deficits from complex systems such as the human brain. However, we provide important insight and a quantitative framework for disorders in which FAS are implicated. Copyright © 2018 Elsevier Inc. All rights reserved.

Inhibition of Ku70 acetylation by INHAT subunit SET/TAF-Iβ regulates Ku70-mediated DNA damage response.

PubMed

Kim, Kee-Beom; Kim, Dong-Wook; Park, Jin Woo; Jeon, Young-Joo; Kim, Daehwan; Rhee, Sangmyung; Chae, Jung-Il; Seo, Sang-Beom

2014-07-01

DNA double-strand breaks (DSBs) can cause either cell death or genomic instability. The Ku heterodimer Ku70/80 is required for the NHEJ (non-homologous end-joining) DNA DSB repair pathway. The INHAT (inhibitor of histone acetyltransferases) complex subunit, SET/TAF-Iβ, can inhibit p300- and PCAF-mediated acetylation of both histone and p53, thereby repressing general transcription and that of p53 target genes. Here, we show that SET/TAF-Iβ interacts with Ku70/80, and that this interaction inhibits CBP- and PCAF-mediated Ku70 acetylation in an INHAT domain-dependent manner. Notably, DNA damage by UV disrupted the interaction between SET/TAF-Iβ and Ku70. Furthermore, we demonstrate that overexpressed SET/TAF-Iβ inhibits recruitment of Ku70/80 to DNA damage sites. We propose that dysregulation of SET/TAF-Iβ expression prevents repair of damaged DNA and also contributes to cellular proliferation. All together, our findings indicate that SET/TAF-Iβ interacts with Ku70/80 in the nucleus and inhibits Ku70 acetylation. Upon DNA damage, SET/TAF-Iβ dissociates from the Ku complex and releases Ku70/Ku80, which are then recruited to DNA DSB sites via the NHEJ DNA repair pathway.

Role of phenolics from Spondias pinnata bark in amelioration of iron overload induced hepatic damage in Swiss albino mice.

PubMed

Chaudhuri, Dipankar; Ghate, Nikhil Baban; Panja, Sourav; Mandal, Nripendranath

2016-07-26

Crude Spondias pinnata bark extract was previously assessed for its antioxidant, anticancer and iron chelating potentials. The isolated compounds gallic acid (GA) and methyl gallate (MG) were evaluated for their curative potential against iron overload-induced liver fibrosis and hepatocellular damage. In vitro iron chelation property and in vivo ameliorating potential from iron overload induced liver toxicity of GA and MG was assessed by different biochemical assays and histopathological studies. MG and GA demonstrated excellent reducing power activities but iron chelation potential of MG is better than GA. Oral MG treatment in mice displayed excellent efficacy (better than GA) to significantly restore the levels of liver antioxidants, serum markers and cellular reactive oxygen species in a dose-dependent fashion. Apart from these, MG exceptionally prevented lipid peroxidation and protein oxidation whereas GA demonstrated better activity to reduce collagen content, thereby strengthening its position as an efficient drug against hepatic damage/fibrosis, which was further supported by histopathological studies. Alongside, MG efficiently eliminated the cause of liver damage, i.e., excess iron, by chelating free iron and reducing the ferritin-bound iron. The present study confirmed the curative effect of GA and MG against iron overload hepatic damage via their potent antioxidant and iron-chelating potential.

Copper-mediated DNA damage by the neurotransmitter dopamine and L-DOPA: A pro-oxidant mechanism.

PubMed

Rehmani, Nida; Zafar, Atif; Arif, Hussain; Hadi, Sheikh Mumtaz; Wani, Altaf A

2017-04-01

Oxidative DNA damage has been implicated in the pathogenesis of neurological disorders, cancer and ageing. Owing to the established link between labile copper concentrations and neurological diseases, it is critical to explore the interactions of neurotransmitters and drug supplements with copper. Herein, we investigate the pro-oxidant DNA damage induced by the interaction of L-DOPA and dopamine (DA) with copper. The DNA binding affinity order of the compounds has been determined by in silico molecular docking. Agarose gel electrophoresis reveals that L-DOPA and DA are able to induce strand scission in plasmid pcDNA3.1 (+/-) in a copper dependent reaction. These metabolites also cause cellular DNA breakage in human lymphocytes by mobilizing endogenous copper, as assessed by comet assay. Further, L-DOPA and DA-mediated DNA breaks were detected by the appearance of post-DNA damage sensitive marker γH2AX in cancer cell lines accumulating high copper. Immunofluorescence demonstrated the co-localization of downstream repair factor 53BP1 at the damaged induced γH2AX foci in cancer cells. The present study corroborates and provides a mechanism to the hypothesis that suggests metal-mediated oxidation of catecholamines contributes to the pathogenesis of neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cellular defense against singlet oxygen-induced oxidative damage by cytosolic NADP+-dependent isocitrate dehydrogenase.

PubMed

Kim, Sun Yee; Park, Jeen-Woo

2003-03-01

Singlet oxygen (1O2) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. Recently, we have shown that NADP+-dependent isocitrate dehydrogenase is involved in the supply of NADPH needed for GSH production against cellular oxidative damage. In this study, we investigated the role of cytosolic form of NADP+-dependent isocitrate dehydrogenase (IDPc) against singlet oxygen-induced cytotoxicity by comparing the relative degree of cellular responses in three different NIH3T3 cells with stable transfection with the cDNA for mouse IDPc in sense and antisense orientations, where IDPc activities were 2.3-fold higher and 39% lower, respectively, than that in the parental cells carrying the vector alone. Upon exposure to singlet oxygen generated from photoactivated dye, the cells with low levels of IDPc became more sensitive to cell killing. Lipid peroxidation, protein oxidation, oxidative DNA damage and intracellular peroxide generation were higher in the cell-line expressing the lower level of IDPc. However, the cells with the highly over-expressed IDPc exhibited enhanced resistance against singlet oxygen, compared to the control cells. The data indicate that IDPc plays an important role in cellular defense against singlet oxygen-induced oxidative injury.

Uptake of gentamicin by separated, viable renal tubules from rabbits.

PubMed

Barza, M; Murray, T; Hamburger, R J

1980-04-01

The proximal renal tubules have a marked affinity for gentamicin; they also are the major site of nephrotoxicity caused by this drug. The uptake of radiolabeled gentamicin in separated, viable renal tubules prepared by enzymatic digestion of rabbit kidneys was studied. The preparations showed rapid initial uptake of gentamicin followed by continued slower uptake. Accumulation was not affected by pH, but was significantly inhibited by ouabain, dinitrophenol, anoxia, and hypothermia in the absence of evident cellular damage. At gentamicin concentrations of greater than 50 microgram/ml in the medium, there was competition for drug uptake. Gentamicin efflux in tubules that were taken from a medium containing antibiotic and placed into antibiotic-free fluid was slow and incomplete. From these data it appears that gentamicin uptake by separated renal tubules occurs by a process that requires metabolic energy; thereafter, the drug resides in a poorly exchangeable cellular pool.

Two-material optimization of plate armour for blast mitigation using hybrid cellular automata

NASA Astrophysics Data System (ADS)

Goetz, J.; Tan, H.; Renaud, J.; Tovar, A.

2012-08-01

With the increased use of improvised explosive devices in regions at war, the threat to military and civilian life has risen. Cabin penetration and gross acceleration are the primary threats in an explosive event. Cabin penetration crushes occupants, damaging the lower body. Acceleration causes death at high magnitudes. This investigation develops a process of designing armour that simultaneously mitigates cabin penetration and acceleration. The hybrid cellular automaton (HCA) method of topology optimization has proven efficient and robust in problems involving large, plastic deformations such as crash impact. Here HCA is extended to the design of armour under blast loading. The ability to distribute two metallic phases, as opposed to one material and void, is also added. The blast wave energy transforms on impact into internal energy (IE) inside the solid medium. Maximum attenuation occurs with maximized IE. The resulting structures show HCA's potential for designing blast mitigating armour structures.

Nickel impact on human health: An intrinsic disorder perspective.

PubMed

Zambelli, Barbara; Uversky, Vladimir N; Ciurli, Stefano

2016-12-01

The interplay of the presence of nickel and protein disorder in processes affecting human health is the focus of the present review. Many systems involving nickel as either a cofactor or as a toxic contaminant are characterized by large disorder. The role of nickel in the biochemistry of bacterial enzymes is discussed here, covering both the beneficial effects of nickel in the human microbiota as well as the role of nickel-depending bacteria in human pathogenesis. In addition, the hazardous health effects caused by nickel exposure to humans, namely nickel-induced carcinogenesis and allergy, are triggered by non-specific interactions of nickel with macromolecules and formation of reactive compounds that mediate cellular damage. Cellular response to nickel is also related to signal transduction cascades. This review thus highlights the most promising systems for future studies aimed at decreasing the adverse effects of nickel on human health. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma generated in culture medium induces damages of HeLa cells due to flow phenomena

NASA Astrophysics Data System (ADS)

Sato, Yusuke; Sato, Takehiko; Yoshino, Daisuke

2018-03-01

Plasma in a liquid has been anticipated as an effective tool for medical applications, however, few reports have described cellular responses to plasma generated in a liquid similar to biological fluids. Herein we report the effects of plasma generated in a culture medium on HeLa cells. The plasma in the culture medium produced not only heat, shock waves, and reactive chemical species but also a jet flow with sub millimeter-sized bubbles. Cells exposed to the plasma exhibited detachment, morphological changes, and changes in the actin cytoskeletal structure. The experimental results suggest that wall shear stress over 160 Pa was generated on the surface of the cells by the plasma. It is one of the main factors that cause those cellular responses. We believe that our findings would provide valuable insight into advancements in medical applications of plasma in a liquid.

Metabolic Dysregulation in Amyotrophic Lateral Sclerosis: Challenges and Opportunities

PubMed Central

Joardar, Archi; Manzo, Ernesto

2017-01-01

Purpose of Review Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease for which there is no cure and treatments are at best palliative. Several genes have been linked to ALS, which highlight defects in multiple cellular processes including RNA processing, proteostasis and metabolism. Clinical observations have identified glucose intolerance and dyslipidemia as key features of ALS however the causes of these metabolic alterations remain elusive. Recent Findings Recent studies reveal that motor neurons and muscle cells may undergo cell type specific metabolic changes that lead to utilization of alternate fuels. For example, ALS patients’ muscles exhibit reduced glycolysis and increased reliance on fatty acids. In contrast, ALS motor neurons contain damaged mitochondria and exhibit impaired lipid beta oxidation, potentially leading to increased glycolysis as a compensatory mechanism. Summary These findings highlight the complexities of metabolic alterations in ALS and provide new opportunities for designing therapeutic strategies based on restoring cellular energetics. PMID:29057168

Metabolic Dysregulation in Amyotrophic Lateral Sclerosis: Challenges and Opportunities.

PubMed

Joardar, Archi; Manzo, Ernesto; Zarnescu, Daniela C

2017-06-01

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease for which there is no cure and treatments are at best palliative. Several genes have been linked to ALS, which highlight defects in multiple cellular processes including RNA processing, proteostasis and metabolism. Clinical observations have identified glucose intolerance and dyslipidemia as key features of ALS however the causes of these metabolic alterations remain elusive. Recent studies reveal that motor neurons and muscle cells may undergo cell type specific metabolic changes that lead to utilization of alternate fuels. For example, ALS patients' muscles exhibit reduced glycolysis and increased reliance on fatty acids. In contrast, ALS motor neurons contain damaged mitochondria and exhibit impaired lipid beta oxidation, potentially leading to increased glycolysis as a compensatory mechanism. These findings highlight the complexities of metabolic alterations in ALS and provide new opportunities for designing therapeutic strategies based on restoring cellular energetics.

What’s the Damage? The Impact of Pathogens on Pathways that Maintain Host Genome Integrity

PubMed Central

Weitzman, Matthew D.; Weitzman, Jonathan B.

2014-01-01

Maintaining genome integrity and transmission of intact genomes is critical for cellular, organismal, and species survival. Cells can detect damaged DNA, activate checkpoints, and either enable DNA repair or trigger apoptosis to eliminate the damaged cell. Aberrations in these mechanisms lead to somatic mutations and genetic instability, which are hallmarks of cancer. Considering the long history of host-microbe coevolution, an impact of microbial infection on host genome integrity is not unexpected, and emerging links between microbial infections and oncogenesis further reinforce this idea. In this review, we compare strategies employed by viruses, bacteria, and parasites to alter, subvert, or otherwise manipulate host DNA damage and repair pathways. We highlight how microbes contribute to tumorigenesis by directly inducing DNA damage, inactivating checkpoint controls, or manipulating repair processes. We also discuss indirect effects resulting from inflammatory responses, changes in cellular metabolism, nuclear architecture, and epigenome integrity, and the associated evolutionary tradeoffs. PMID:24629335

Physiological imaging of electrical trauma and therapeutic responses

NASA Astrophysics Data System (ADS)

Chen, Chin-Tu; Matthews, K.; Aarsvold, John N.; Mintzer, Robert A.; Yasillo, Nicholas J.; Hannig, Jurgen; Capelli-Schellpfefer, M.; Cooper, Malcolm; Lee, Raphael C.

2000-04-01

In victims of electrical trauma, electroporation of cell membrane, in which lipid bilayer is permeabilized by thermal and electrical forces, is thought to be a substantial cause of tissue damage. It has been suggested that certain mild surfactant in low concentration could induce sealing of permeabilized lipid bilayers, thus repairing cell membranes that had not been extensively damaged. With an animal model of electrically injured hind limb of rats, we have demonstrated and validated the use of radiotracer imaging technique to assess the physiology of the damaged tissues after electrical shock and of their repairs after applying surfactant as a therapeutic strategy. For example, using Tc-99m labeled pyrophosphate (PYP), which follows calcium in cellular function and is known to accumulate in damaged tissues, we have established a physiological imaging approach for assessment of the extent of tissue injury for diagnosis and surgical planning, as well as for evaluation of responses to therapy. With the use of a small, hand-held, miniature gamma camera, this physiological imaging method can be employed at patient's bedside and even in the field, for example, at accident site or during transfer for emergency care, rapid diagnosis, and prompt treatment in order to maximize the chance for tissue survival.

Photoprotection beyond ultraviolet radiation--effective sun protection has to include protection against infrared A radiation-induced skin damage.

PubMed

Schroeder, P; Calles, C; Benesova, T; Macaluso, F; Krutmann, J

2010-01-01

Solar radiation is well known to damage human skin, for example by causing premature skin ageing (i.e. photoageing). We have recently learned that this damage does not result from ultraviolet (UV) radiation alone, but also from longer wavelengths, in particular near-infrared radiation (IRA radiation, 760-1,440 nm). IRA radiation accounts for more than one third of the solar energy that reaches human skin. While infrared radiation of longer wavelengths (IRB and IRC) does not penetrate deeply into the skin, more than 65% of the shorter wavelength (IRA) reaches the dermis. IRA radiation has been demonstrated to alter the collagen equilibrium of the dermal extracellular matrix in at least two ways: (a) by leading to an increased expression of the collagen-degrading enzyme matrix metalloproteinase 1, and (b) by decreasing the de novo synthesis of the collagen itself. IRA radiation exposure therefore induces similar biological effects to UV radiation, but the underlying mechanisms are substantially different, specifically, the cellular response to IRA irradiation involves the mitochondrial electron transport chain. Effective sun protection requires specific strategies to prevent IRA radiation-induced skin damage. 2010 S. Karger AG, Basel.

Role of the Renin-Angiotensin-Aldosterone System beyond Blood Pressure Regulation: Molecular and Cellular Mechanisms Involved in End-Organ Damage during Arterial Hypertension

PubMed Central

Muñoz-Durango, Natalia; Fuentes, Cristóbal A.; Castillo, Andrés E.; González-Gómez, Luis Martín; Vecchiola, Andrea; Fardella, Carlos E.; Kalergis, Alexis M.

2016-01-01

Arterial hypertension is a common condition worldwide and an important predictor of several complicated diseases. Arterial hypertension can be triggered by many factors, including physiological, genetic, and lifestyle causes. Specifically, molecules of the renin-angiotensin-aldosterone system not only play important roles in the control of blood pressure, but they are also associated with the genesis of arterial hypertension, thus constituting a need for pharmacological interventions. Chronic high pressure generates mechanical damage along the vascular system, heart, and kidneys, which are the principal organs affected in this condition. In addition to mechanical stress, hypertension-induced oxidative stress, chronic inflammation, and the activation of reparative mechanisms lead to end-organ damage, mainly due to fibrosis. Clinical trials have demonstrated that renin-angiotensin-aldosterone system intervention in hypertensive patients lowers morbidity/mortality and inflammatory marker levels as compared to placebo patients, evidencing that this system controls more than blood pressure. This review emphasizes the detrimental effects that a renin-angiotensin-aldosterone system (RAAS) imbalance has on health considerations above and beyond high blood pressure, such as fibrotic end-organ damage. PMID:27347925

Role of the Renin-Angiotensin-Aldosterone System beyond Blood Pressure Regulation: Molecular and Cellular Mechanisms Involved in End-Organ Damage during Arterial Hypertension.

PubMed

Muñoz-Durango, Natalia; Fuentes, Cristóbal A; Castillo, Andrés E; González-Gómez, Luis Martín; Vecchiola, Andrea; Fardella, Carlos E; Kalergis, Alexis M

2016-06-23

Arterial hypertension is a common condition worldwide and an important predictor of several complicated diseases. Arterial hypertension can be triggered by many factors, including physiological, genetic, and lifestyle causes. Specifically, molecules of the renin-angiotensin-aldosterone system not only play important roles in the control of blood pressure, but they are also associated with the genesis of arterial hypertension, thus constituting a need for pharmacological interventions. Chronic high pressure generates mechanical damage along the vascular system, heart, and kidneys, which are the principal organs affected in this condition. In addition to mechanical stress, hypertension-induced oxidative stress, chronic inflammation, and the activation of reparative mechanisms lead to end-organ damage, mainly due to fibrosis. Clinical trials have demonstrated that renin-angiotensin-aldosterone system intervention in hypertensive patients lowers morbidity/mortality and inflammatory marker levels as compared to placebo patients, evidencing that this system controls more than blood pressure. This review emphasizes the detrimental effects that a renin-angiotensin-aldosterone system (RAAS) imbalance has on health considerations above and beyond high blood pressure, such as fibrotic end-organ damage.

Oxalomalate, a competitive inhibitor of NADP+-dependent isocitrate dehydrogenase, enhances lipid peroxidation-mediated oxidative damage in U937 cells.

PubMed

Yang, Joon-Hyuck; Park, Jeen-Woo

2003-08-01

Membrane lipid peroxidation processes yield products that may react with DNA and proteins to cause oxidative modifications. Cytosolic NADP+-dependent isocitrate dehydrogenase (ICDH) in U937 cells produces NADPH, an essential reducing equivalent for the antioxidant system. The protective role of ICDH against lipid peroxidation-mediated oxidative damage in U937 cells was investigated in control cells pre-treated with oxalomalate, a competitive inhibitor of ICDH. Upon exposure to 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) to U937 cells, which induces lipid peroxidation in membranes, the viability was lower and the protein oxidation, lipid peroxidation, and oxidative DNA damage, reflected by an increase in 8-hydroxy-2'-deoxyguanosine, were higher in oxalomalate-treated cells as compared to control cells. We also observed the significant increase in the endogenous production of reactive oxygen species, as measured by the oxidation of 2',7'-dichlorodihydrofluorescin, as well as the significant decrease in the intracellular GSH level in oxalomalate-treated U937 cells upon exposure to AAPH. These results suggest that ICDH plays an important role as an antioxidant enzyme in cellular defense against lipid peroxidation-mediated oxidative damage through the removal of reactive oxygen species.

Testicular cellular toxicity of cadmium : transmission electron microscopy examination.

PubMed

Haffor, A S; Abou-Tarboush, F M

2004-07-01

It is clear that environmental heavy metals influence life systems and reproductive system. In the present study histological investigation revealed that cadmium was testicular toxicant in mice. Here we compared the fine-structure of spermatogenesis in two groups of mice (SWR), experimental and control. The experimental group underwent cadmium ingestion at 1 mg/kg daily for 4 weeks. The control group underwent ingestion of distilled water with equal dosages, using the same type of injectors, for 4-weeks. After cadmium exposure period both control and experimental groups were killed and samples of the testes were processed for microscopic examination. Ultra sections were examined and photographed by Transmission Electron Microscope (JEOL- 100SX) at 80KV. Ultrastructure examination revealed, vascular endothelial, interstitial, and sertoli cells damages. Early impairments of germinal cellular differentiation resulted in deformations in all parts of late spermatid. There were dislocation of accrosomal granules, nuclear damage associated with chromatin heterogeneity, detached spermatid from the apical process of sertoli cell, disarrangement of the mitochondria, abnormal oriented tail piece, and abnormal microtubules complex. These ultra morphological abnormalities relate to cell injury and to the resulting physiological abnormality, necrobiosis. Based on the results of this investigation it can be concluded that cadmium ingestion at 1000 microg/kg caused testicular toxicity and abnormalities in early sperm development.

Inactivation of thiol-dependent enzymes by hypothiocyanous acid: role of sulfenyl thiocyanate and sulfenic acid intermediates

PubMed Central

Barrett, Tessa J.; Pattison, David I.; Leonard, Stephen E.; Carroll, Kate S.; Davies, Michael J.; Hawkins, Clare L.

2012-01-01

Myeloperoxidase (MPO) forms reactive oxidants including hypochlorous and hypothiocyanous acids (HOCl and HOSCN) under inflammatory conditions. HOCl causes extensive tissue damage and plays a role in the progression of many inflammatory-based diseases. Although HOSCN is a major MPO oxidant, particularly in smokers, who have elevated plasma thiocyanate, the role of this oxidant in disease is poorly characterized. HOSCN induces cellular damage by targeting thiols. However, the specific targets and mechanisms involved in this process are not well defined. We show that exposure of macrophages to HOSCN results in the inactivation of intracellular enzymes, including creatine kinase (CK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In each case, the active-site thiol residue is particularly sensitive to oxidation, with evidence for reversible inactivation and the formation of sulfenyl thiocyanate and sulfenic acid intermediates, on treatment with HOSCN (less than fivefold molar excess). Experiments with DAz-2, a cell-permeable chemical trap for sulfenic acids, demonstrate that these intermediates are formed on many cellular proteins, including GAPDH and CK, in macrophages exposed to HOSCN. This is the first direct evidence for the formation of protein sulfenic acids in HOSCN-treated cells and highlights the potential of this oxidant to perturb redox signaling processes. PMID:22248862

Augmenting autophagy for prognosis based intervention of COPD-pathophysiology.

PubMed

Bodas, Manish; Vij, Neeraj

2017-05-04

Chronic obstructive pulmonary disease (COPD) is foremost among the non-reversible fatal ailments where exposure to tobacco/biomass-smoke and aging are the major risk factors for the initiation and progression of the obstructive lung disease. The role of smoke-induced inflammatory-oxidative stress, apoptosis and cellular senescence in driving the alveolar damage that mediates the emphysema progression and severe lung function decline is apparent, although the central mechanism that regulates these processes was unknown. To fill in this gap in knowledge, the central role of proteostasis and autophagy in regulating chronic lung disease causing mechanisms has been recently described. Recent studies demonstrate that cigarette/nicotine exposure induces proteostasis/autophagy-impairment that leads to perinuclear accumulation of polyubiquitinated proteins as aggresome-bodies, indicative of emphysema severity. In support of this concept, autophagy inducing FDA-approved anti-oxidant drugs control tobacco-smoke induced inflammatory-oxidative stress, apoptosis, cellular senescence and COPD-emphysema progression in variety of preclinical models. Hence, we propose that precise and early detection of aggresome-pathology can allow the timely assessment of disease severity in COPD-emphysema subjects for prognosis-based intervention. While intervention with autophagy-inducing drugs is anticipated to reduce alveolar damage and lung function decline, resulting in a decrease in the current mortality rates in COPD-emphysema subjects.

Thermal Shock Induces Host Proteostasis Disruption and Endoplasmic Reticulum Stress in the Model Symbiotic Cnidarian Aiptasia.

PubMed

Oakley, Clinton A; Durand, Elysanne; Wilkinson, Shaun P; Peng, Lifeng; Weis, Virginia M; Grossman, Arthur R; Davy, Simon K

2017-06-02

Coral bleaching has devastating effects on coral survival and reef ecosystem function, but many of the fundamental cellular effects of thermal stress on cnidarian physiology are unclear. We used label-free liquid chromatography-tandem mass spectrometry to compare the effects of rapidly (33.5 °C, 24 h) and gradually (30 and 33.5 °C, 12 days) elevated temperatures on the proteome of the model symbiotic anemone Aiptasia. We identified 2133 proteins in Aiptasia, 136 of which were differentially abundant between treatments. Thermal shock, but not acclimation, resulted in significant abundance changes in 104 proteins, including those involved in protein folding and synthesis, redox homeostasis, and central metabolism. Nineteen abundant structural proteins showed particularly reduced abundance, demonstrating proteostasis disruption and potential protein synthesis inhibition. Heat shock induced antioxidant mechanisms and proteins involved in stabilizing nascent proteins, preventing protein aggregation and degrading damaged proteins, which is indicative of endoplasmic reticulum stress. Host proteostasis disruption occurred before either bleaching or symbiont photoinhibition was detected, suggesting host-derived reactive oxygen species production as the proximate cause of thermal damage. The pronounced abundance changes in endoplasmic reticulum proteins associated with proteostasis and protein turnover indicate that these processes are essential in the cellular response of symbiotic cnidarians to severe thermal stress.

Protein Phosphatase Pph3 and Its Regulatory Subunit Psy2 Regulate Rad53 Dephosphorylation and Cell Morphogenesis during Recovery from DNA Damage in Candida albicans ▿

PubMed Central

Sun, Ling Ling; Li, Wan Jie; Wang, Hai Tao; Chen, Jie; Deng, Ping; Wang, Yue; Sang, Jian Li

2011-01-01

The ability of the pathogenic fungus Candida albicans to switch cellular morphologies is important for infection and virulence. Recent studies have revealed that C. albicans yeast cells can switch to filamentous growth under genotoxic stress in a manner dependent on the DNA replication/damage checkpoint. Here, we have investigated the functions of Pph3 (orf19.4378) and Psy2 (orf19.3685), whose orthologues in Saccharomyces cerevisiae mediate the dephosphorylation of the DNA damage checkpoint kinase Rad53 and the histone variant H2AX during recovery from DNA damage. Deleting PPH3 or PSY2 causes hypersensitivity to DNA-damaging agents, including cisplatin, methylmethane sulfonate (MMS), and UV light. In addition, pph3Δ and psy2Δ cells exhibit strong filamentous growth under genotoxic stress. Flow cytometry analysis shows that the mutant cells have lost the ability to adapt to genotoxic stress and remain arrested even after the stress is withdrawn. Furthermore, we show that Pph3 and Psy2 are required for the dephosphorylation of Rad53, but not H2AX, during DNA damage recovery. Taken together, these results show that C. albicans Pph3 and Psy2 have important roles in mediating genotoxin-induced filamentous growth and regulating Rad53 dephosphorylation. PMID:21890819

Hydrogen Peroxide, Signaling in Disguise during Metal Phytotoxicity

PubMed Central

Cuypers, Ann; Hendrix, Sophie; Amaral dos Reis, Rafaela; De Smet, Stefanie; Deckers, Jana; Gielen, Heidi; Jozefczak, Marijke; Loix, Christophe; Vercampt, Hanne; Vangronsveld, Jaco; Keunen, Els

2016-01-01

Plants exposed to excess metals are challenged by an increased generation of reactive oxygen species (ROS) such as superoxide (O2•-), hydrogen peroxide (H2O2) and the hydroxyl radical (•OH). The mechanisms underlying this oxidative challenge are often dependent on metal-specific properties and might play a role in stress perception, signaling and acclimation. Although ROS were initially considered as toxic compounds causing damage to various cellular structures, their role as signaling molecules became a topic of intense research over the last decade. Hydrogen peroxide in particular is important in signaling because of its relatively low toxicity, long lifespan and its ability to cross cellular membranes. The delicate balance between its production and scavenging by a plethora of enzymatic and metabolic antioxidants is crucial in the onset of diverse signaling cascades that finally lead to plant acclimation to metal stress. In this review, our current knowledge on the dual role of ROS in metal-exposed plants is presented. Evidence for a relationship between H2O2 and plant metal tolerance is provided. Furthermore, emphasis is put on recent advances in understanding cellular damage and downstream signaling responses as a result of metal-induced H2O2 production. Finally, special attention is paid to the interaction between H2O2 and other signaling components such as transcription factors, mitogen-activated protein kinases, phytohormones and regulating systems (e.g. microRNAs). These responses potentially underlie metal-induced senescence in plants. Elucidating the signaling network activated during metal stress is a pivotal step to make progress in applied technologies like phytoremediation of polluted soils. PMID:27199999

Assessment of photodynamic damage on Escherichia coli via atomic force microscopy

NASA Astrophysics Data System (ADS)

Núñez, Silvia Cristina; Simões Ribeiro, Martha; Silva Garcez, Aguinaldo; Miyakawa, Walter

2010-04-01

Photodynamic antimicrobial therapy (PAT) may become a useful clinical tool to treat microbial infections, overcoming microbial resistance that is a major problem nowadays. The aim of our work was to verify the damage caused by photosensitization over a Escherichia col) via atomic force microscopy (AFM), looking for structural changes that might occur in cells after PAT. Cells culture were grown until a stationary phase to reach a concentration of approximately 108 cells/mL allowing the production of extracellular slime in a biofilm-like structure. The cells including the extracellular matrix were put in a slide and its structure was observed using AFM; subsequently a water solution of methylene blue at 60μM was applied over the cells and a pre-irradiation time of 3 minutes was waited and followed by illumination with a diode laser (λ=660nm, power 40mW, 3min, fluence 180J/cm2, beam diameter 0.04cm2). The same cells were observed and the images stored. A second set of experiments was performed with a smaller number of cells/area and without extracellular slime, using the parameters abovementioned. The results showed alterations on cellular scaffold markedly dependent on the number of cells and the presence of extracellular slime. The slime is targeted by the photosensitizer, and after irradiation a destruction of the matrix was observed; when fewer cells were evaluated the destruction is much more evident. The images suggested rupture of the cellular membrane and cellular fragments were observed. Our findings indicate that AFM seems is a useful tool to investigate parameters linked with photodestruction of microorganisms.

Polyhydroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells.

PubMed

Rosenblat, Gennady; Meretski, Shai; Segal, Joseph; Tarshis, Mark; Schroeder, Avi; Zanin-Zhorov, Alexandra; Lion, Gilead; Ingber, Arieh; Hochberg, Malka

2011-05-01

Exposing skin to ultraviolet (UV) radiation contributes to photoaging and to the development of skin cancer by DNA lesions and triggering inflammatory and other harmful cellular cascades. The present study tested the ability of unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, to reduce UVB-induced damage and inflammation in skin. Introducing PFA to keratinocytes prior to their exposure to UVB exerted a protective effect, increasing cell viability, decreasing the secretion of IL-6 and PGE(2), and enhancing DNA repair. In human skin explants, treating with PFA reduced significantly UV-induced cellular damage. These results support the idea that PFA can play an important role as a photo-protective agent in UV-induced skin damage.

The cochlear CRF signaling systems and their mechanisms of action in modulating cochlear sensitivity and protection against trauma

PubMed Central

Graham, Christine E.; Basappa, Johnvesly; Turcan, Sevin; Vetter, Douglas E.

2011-01-01

A key requirement for encoding the auditory environment is the ability to dynamically alter cochlear sensitivity. However, merely attaining a steady state of maximal sensitivity is not a viable solution since the sensory cells and ganglion cells of the cochlea are prone to damage following exposure to loud sound. Most often, such damage is via initial metabolic insult that can lead to cellular death. Thus, establishing the highest sensitivity must be balanced with protection against cellular metabolic damage that can lead to loss of hair cells and ganglion cells, resulting in loss of frequency representation. While feedback mechanisms are known to exist in the cochlea that alter sensitivity, they respond only after stimulus encoding, allowing potentially damaging sounds to impact the inner ear at times coincident with increased sensitivity. Thus, questions remain concerning the endogenous signaling systems involved in dynamic modulation of cochlear sensitivity and protection against metabolic stress. Understanding endogenous signaling systems involved in cochlear protection may lead to new strategies and therapies for prevention of cochlear damage and consequent hearing loss. We have recently discovered a novel cochlear signaling system that is molecularly equivalent to the classic hypothalamic-pituitary-adrenal (HPA) axis. This cochlear HPA-equivalent system functions to balance auditory sensitivity and susceptibility to noise-induced hearing loss, and also protects against cellular metabolic insults resulting from exposures to ototoxic drugs. We review the anatomy, physiology, and cellular signaling of this system, and compare it to similar signaling in other organs/tissues of the body. PMID:21909974

Radiation-Induced Loss of Salivary Gland Function Is Driven by Cellular Senescence and Prevented by IL6 Modulation.

PubMed

Marmary, Yitzhak; Adar, Revital; Gaska, Svetlana; Wygoda, Annette; Maly, Alexander; Cohen, Jonathan; Eliashar, Ron; Mizrachi, Lina; Orfaig-Geva, Carmit; Baum, Bruce J; Rose-John, Stefan; Galun, Eithan; Axelrod, Jonathan H

2016-03-01

Head and neck cancer patients treated by radiation commonly suffer from a devastating side effect known as dry-mouth syndrome, which results from the irreversible loss of salivary gland function via mechanisms that are not completely understood. In this study, we used a mouse model of radiation-induced salivary hypofunction to investigate the outcomes of DNA damage in the head and neck region. We demonstrate that the loss of salivary function was closely accompanied by cellular senescence, as evidenced by a persistent DNA damage response (γH2AX and 53BP1) and the expression of senescence-associated markers (SA-βgal, p19ARF, and DcR2) and secretory phenotype (SASP) factors (PAI-1 and IL6). Notably, profound apoptosis or necrosis was not observed in irradiated regions. Signs of cellular senescence were also apparent in irradiated salivary glands surgically resected from human patients who underwent radiotherapy. Importantly, using IL6 knockout mice, we found that sustained expression of IL6 in the salivary gland long after initiation of radiation-induced DNA damage was required for both senescence and hypofunction. Additionally, we demonstrate that IL6 pretreatment prevented both senescence and salivary gland hypofunction via a mechanism involving enhanced DNA damage repair. Collectively, these results indicate that cellular senescence is a fundamental mechanism driving radiation-induced damage in the salivary gland and suggest that IL6 pretreatment may represent a promising therapeutic strategy to preserve salivary gland function in head and neck cancer patients undergoing radiotherapy. ©2016 American Association for Cancer Research.

Repeated exposure of mouse dermal fibroblasts at a sub-cytotoxic dose of UVB leads to premature senescence: a robust model of cellular photoaging.

PubMed

Zeng, Ji-ping; Bi, Bo; Chen, Liang; Yang, Ping; Guo, Yu; Zhou, Yi-qun; Liu, Tian-yi

2014-01-01

Photoaging skin is due to accumulative effect of UV irradiation that mainly imposes its damage on dermal fibroblasts. To mimic the specific cellular responses invoked by long term effect of UVB, it is preferable to develop a photo-damaged model in vitro based on repeated UVB exposure instead of a single exposure. To develop a photo-damaged model of fibroblasts by repeated UVB exposure allowing for investigation of molecular mechanism underlying premature senescence and testing of potential anti-photoaging compounds. Mouse dermal fibroblasts (MDFs) at early passages (passages 1-3) were exposed to a series of 4 sub-cytotoxic dose of UVB. The senescent phenotypes were detected at 24 or 48h after the last irradiation including cell viability, ROS generation, mitochondrial membrane potential, cell cycle, production and degradation of extracellular matrix. Repeated exposure of UVB resulted in remarkable features of senescence. It effectively avoided the disadvantages of single dose such as induction of cell death rather than senescence, inadequate stress resulting in cellular self-rehabilitation. Our work confirms the possibility of detecting cellular machinery that mediates UVB damage to fibroblasts in vitro by repeated exposure, while the potential molecular mechanisms including cell surface receptors, protein kinase signal transduction pathways, and transcription factors remain to be further evaluated. Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

The effects of the Er:YAG laser on trabecular bone micro-architecture: Comparison with conventional dental drilling by micro-computed tomographic and histological techniques

PubMed Central

Zeitouni, Jihad; Clough, Bret; Zeitouni, Suzanne; Saleem, Mohammed; Al Aisami, Kenan; Gregory, Carl

2017-01-01

Background: The use of lasers has become increasingly common in the field of medicine and dentistry, and there is a growing need for a deeper understanding of the procedure and its effects on tissue. The aim of this study was to compare the erbium-doped yttrium aluminium garnet (Er:YAG) laser and conventional drilling techniques, by observing the effects on trabecular bone microarchitecture and the extent of thermal and mechanical damage. Methods: Ovine femoral heads were employed to mimic maxillofacial trabecular bone, and cylindrical osteotomies were generated to mimic implant bed preparation. Various laser parameters were tested, as well as a conventional dental drilling technique. The specimens were then subjected to micro-computed tomographic (μCT) histomorphometic analysis and histology. Results: Herein, we demonstrate that mCT measurements of trabecular porosity provide quantitative evidence that laser-mediated cutting preserves the trabecular architecture and reduces thermal and mechanical damage at the margins of the cut. We confirmed these observations with histological studies. In contrast with laser-mediated cutting, conventional drilling resulted in trabecular collapse, reduction of porosity at the margin of the cut and histological signs of thermal damage. Conclusions: This study has demonstrated, for the first time, that mCT and quantification of porosity at the margin of the cut provides a quantitative insight into damage caused by bone cutting techniques. We further show that with laser-mediated cutting, the marrow remains exposed to the margins of the cut, facilitating cellular infiltration and likely accelerating healing. However, with drilling, trabecular collapse and thermal damage is likely to delay healing by restricting the passage of cells to the site of injury and causing localized cell death. PMID:29416849

DNA Damage Following Pulmonary Exposure by Instillation to Low Doses of Carbon Black (Printex 90) Nanoparticles in Mice

PubMed Central

Kyjovska, Zdenka O; Jacobsen, Nicklas R; Saber, Anne T; Bengtson, Stefan; Jackson, Petra; Wallin, Håkan; Vogel, Ulla

2015-01-01

We previously observed genotoxic effects of carbon black nanoparticles at low doses relative to the Danish Occupational Exposure Limit (3.5 mg/m3). Furthermore, DNA damage occurred in broncho-alveolar lavage (BAL) cells in the absence of inflammation, indicating that inflammation is not required for the genotoxic effects of carbon black. In this study, we investigated inflammatory and acute phase response in addition to genotoxic effects occurring following exposure to nanoparticulate carbon black (NPCB) at even lower doses. C57BL/6JBomTac mice were examined 1, 3, and 28 days after a single instillation of 0.67, 2, 6, and 162 µg Printex 90 NPCB and vehicle. Cellular composition and protein concentration was evaluated in BAL fluid as markers of inflammatory response and cell damage. DNA strand breaks in BAL cells, lung, and liver tissue were assessed using the alkaline comet assay. The pulmonary acute phase response was analyzed by Saa3 mRNA real-time quantitative PCR. Instillation of the low doses of NPCB induced a slight neutrophil influx one day after exposure. Pulmonary exposure to small doses of NPCB caused an increase in DNA strand breaks in BAL cells and lung tissue measured using the comet assay. We interpret the increased DNA strand breaks occurring following these low exposure doses of NPCB as DNA damage caused by primary genotoxicity in the absence of substantial inflammation, cell damage, and acute phase response. Environ. Mol. Mutagen. 56:41–49, 2015. © 2014 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society PMID:25042074

Enterococcus faecalis infection causes inflammation, intracellular oxphos-independent ROS production, and DNA damage in human gastric cancer cells.

PubMed

Strickertsson, Jesper A B; Desler, Claus; Martin-Bertelsen, Tomas; Machado, Ana Manuel Dantas; Wadstrøm, Torkel; Winther, Ole; Rasmussen, Lene Juel; Friis-Hansen, Lennart

2013-01-01

Achlorhydria caused by e.g. atrophic gastritis allows for bacterial overgrowth, which induces chronic inflammation and damage to the mucosal cells of infected individuals driving gastric malignancies and cancer. Enterococcus faecalis (E. faecalis) can colonize achlohydric stomachs and we therefore wanted to study the impact of E. faecalis infection on inflammatory response, reactive oxygen species (ROS) formation, mitochondrial respiration, and mitochondrial genetic stability in gastric mucosal cells. To separate the changes induced by bacteria from those of the inflammatory cells we established an in vitro E. faecalis infection model system using the gastric carcinoma cell line MKN74. Total ROS and superoxide was measured by fluorescence microscopy. Cellular oxygen consumption was characterized non-invasively using XF24 microplate based respirometry. Gene expression was examined by microarray, and response pathways were identified by Gene Set Analysis (GSA). Selected gene transcripts were verified by quantitative real-time polymerase chain reaction (qRT-PCR). Mitochondrial mutations were determined by sequencing. Infection of MKN74 cells with E. faecalis induced intracellular ROS production through a pathway independent of oxidative phosphorylation (oxphos). Furthermore, E. faecalis infection induced mitochondrial DNA instability. Following infection, genes coding for inflammatory response proteins were transcriptionally up-regulated while DNA damage repair and cell cycle control genes were down-regulated. Cell growth slowed down when infected with viable E. faecalis and responded in a dose dependent manner to E. faecalis lysate. Infection by E. faecalis induced an oxphos-independent intracellular ROS response and damaged the mitochondrial genome in gastric cell culture. Finally the bacteria induced an NF-κB inflammatory response as well as impaired DNA damage response and cell cycle control gene expression. Array Express accession number E-MEXP-3496.

The long and short of it: the role of telomeres in fetal origins of adult disease.

PubMed

Hallows, Stephanie E; Regnault, Timothy R H; Betts, Dean H

2012-01-01

Placental insufficiency, maternal malnutrition, and other causes of intrauterine growth restriction (IUGR) can significantly affect short-term growth and long-term health. Following IUGR, there is an increased risk for cardiovascular disease and Type 2 Diabetes. The etiology of these diseases is beginning to be elucidated, and premature aging or cellular senescence through increased oxidative stress and DNA damage to telomeric ends may be initiators of these disease processes. This paper will explore the areas where telomere and telomerase biology can have significant effects on various tissues in the body in IUGR outcomes.

Repair-Resistant DNA Lesions

PubMed Central

2017-01-01

The eukaryotic global genomic nucleotide excision repair (GG-NER) pathway is the major mechanism that removes most bulky and some nonbulky lesions from cellular DNA. There is growing evidence that certain DNA lesions are repaired slowly or are entirely resistant to repair in cells, tissues, and in cell extract model assay systems. It is well established that the eukaryotic DNA lesion-sensing proteins do not detect the damaged nucleotide, but recognize the distortions/destabilizations in the native DNA structure caused by the damaged nucleotides. In this article, the nature of the structural features of certain bulky DNA lesions that render them resistant to NER, or cause them to be repaired slowly, is compared to that of those that are good-to-excellent NER substrates. Understanding the structural features that distinguish NER-resistant DNA lesions from good NER substrates may be useful for interpreting the biological significance of biomarkers of exposure of human populations to genotoxic environmental chemicals. NER-resistant lesions can survive to replication and cause mutations that can initiate cancer and other diseases. Furthermore, NER diminishes the efficacy of certain chemotherapeutic drugs, and the design of more potent pharmaceuticals that resist repair can be advanced through a better understanding of the structural properties of DNA lesions that engender repair-resistance. PMID:28750166

ROLE OF CENTRAL NERVOUS SYSTEM INSULIN RESISTANCE IN FETAL ALCOHOL SPECTRUM DISORDERS

PubMed Central

de la Monte, Suzanne M; Wands, Jack R

2011-01-01

Fetal alcohol spectrum disorder (FASD) is the most common preventable cause of mental retardation in the USA. Ethanol impairs neuronal survival and function by two major mechanisms: 1) it inhibits insulin signaling required for viability, metabolism, synapse formation, and acetylcholine production; and 2) it functions as a neurotoxicant, causing oxidative stress, DNA damage and mitochondrial dysfunction. Ethanol inhibition of insulin signaling is mediated at the insulin receptor (IR) level and caused by both impaired receptor binding and increased activation of phosphatases that reverse IR tyrosine kinase activity. As a result, insulin activation of PI3K-Akt, which mediates neuronal survival, motility, energy metabolism, and plasticity, is impaired. The neurotoxicant effects of ethanol promote DNA damage, which could contribute to mitochondrial dysfunction and oxidative stress. Therefore, chronic in utero ethanol exposure produces a dual state of CNS insulin resistance and oxidative stress, which we postulate plays a major role in ethanol neurobehavioral teratogenesis. We propose that many of the prominent adverse effects of chronic prenatal exposure to ethanol on CNS development and function may be prevented or reduced by treatment with peroxisome-proliferated activated receptor (PPAR) agonists which enhance insulin sensitivity by increasing expression and function of insulin-responsive genes, and reducing cellular oxidative stress. PMID:21063035

Age-Related Macular Degeneration: New Paradigms for Treatment and Management of AMD

PubMed Central

Zamora-Alvarado, Ruben; Gulias-Cañizo, Rosario; Quiroz-Mercado, Hugo

2018-01-01

Age-related macular degeneration (AMD) is a well-characterized and extensively studied disease. It is currently considered the leading cause of visual disability among patients over 60 years. The hallmark of early AMD is the formation of drusen, pigmentary changes at the macula, and mild to moderate vision loss. There are two forms of AMD: the “dry” and the “wet” form that is less frequent but is responsible for 90% of acute blindness due to AMD. Risk factors have been associated with AMD progression, and they are taking relevance to understand how AMD develops: (1) advanced age and the exposition to environmental factors inducing high levels of oxidative stress damaging the macula and (2) this damage, which causes inflammation inducing a vicious cycle, altogether causing central vision loss. There is neither a cure nor treatment to prevent AMD. However, there are some treatments available for the wet form of AMD. This article will review some molecular and cellular mechanisms associated with the onset of AMD focusing on feasible treatments for each related factor in the development of this pathology such as vascular endothelial growth factor, oxidative stress, failure of the clearance of proteins and organelles, and glial cell dysfunction in AMD. PMID:29484106

Ubiquitylation-dependent regulation of NEIL1 by Mule and TRIM26 is required for the cellular DNA damage response.

PubMed

Edmonds, Matthew J; Carter, Rachel J; Nickson, Catherine M; Williams, Sarah C; Parsons, Jason L

2017-01-25

Endonuclease VIII-like protein 1 (NEIL1) is a DNA glycosylase involved in initiating the base excision repair pathway, the major cellular mechanism for repairing DNA base damage. Here, we have purified the major E3 ubiquitin ligases from human cells responsible for regulation of NEIL1 by ubiquitylation. Interestingly, we have identified two enzymes that catalyse NEIL1 polyubiquitylation, Mcl-1 ubiquitin ligase E3 (Mule) and tripartite motif 26 (TRIM26). We demonstrate that these enzymes are capable of polyubiquitylating NEIL1 in vitro, and that both catalyse ubiquitylation of NEIL1 within the same C-terminal lysine residues. An siRNA-mediated knockdown of Mule or TRIM26 leads to stabilisation of NEIL1, demonstrating that these enzymes are important in regulating cellular NEIL1 steady state protein levels. Similarly, a mutant NEIL1 protein lacking residues for ubiquitylation is more stable than the wild type protein in vivo We also demonstrate that cellular NEIL1 protein is induced in response to ionising radiation (IR), although this occurs specifically in a Mule-dependent manner. Finally we show that stabilisation of NEIL1, particularly following TRIM26 siRNA, contributes to cellular resistance to IR. This highlights the importance of Mule and TRIM26 in maintaining steady state levels of NEIL1, but also those required for the cellular DNA damage response. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Treacher Collins syndrome TCOF1 protein cooperates with NBS1 in the DNA damage response.

PubMed

Ciccia, Alberto; Huang, Jen-Wei; Izhar, Lior; Sowa, Mathew E; Harper, J Wade; Elledge, Stephen J

2014-12-30

The signal transduction pathway of the DNA damage response (DDR) is activated to maintain genomic integrity following DNA damage. The DDR promotes genomic integrity by regulating a large network of cellular activities that range from DNA replication and repair to transcription, RNA splicing, and metabolism. In this study we define an interaction between the DDR factor NBS1 and TCOF1, a nucleolar protein that regulates ribosomal DNA (rDNA) transcription and is mutated in Treacher Collins syndrome. We show that NBS1 relocalizes to nucleoli after DNA damage in a manner dependent on TCOF1 and on casein kinase II and ATM, which are known to modify TCOF1 by phosphorylation. Moreover, we identify a putative ATM phosphorylation site that is required for NBS1 relocalization to nucleoli in response to DNA damage. Last, we report that TCOF1 promotes cellular resistance to DNA damaging agents. Collectively, our findings identify TCOF1 as a DDR factor that could cooperate with ATM and NBS1 to suppress inappropriate rDNA transcription and maintain genomic integrity after DNA damage.

Treacher Collins syndrome TCOF1 protein cooperates with NBS1 in the DNA damage response

PubMed Central

Ciccia, Alberto; Huang, Jen-Wei; Izhar, Lior; Sowa, Mathew E.; Harper, J. Wade; Elledge, Stephen J.

2014-01-01

The signal transduction pathway of the DNA damage response (DDR) is activated to maintain genomic integrity following DNA damage. The DDR promotes genomic integrity by regulating a large network of cellular activities that range from DNA replication and repair to transcription, RNA splicing, and metabolism. In this study we define an interaction between the DDR factor NBS1 and TCOF1, a nucleolar protein that regulates ribosomal DNA (rDNA) transcription and is mutated in Treacher Collins syndrome. We show that NBS1 relocalizes to nucleoli after DNA damage in a manner dependent on TCOF1 and on casein kinase II and ATM, which are known to modify TCOF1 by phosphorylation. Moreover, we identify a putative ATM phosphorylation site that is required for NBS1 relocalization to nucleoli in response to DNA damage. Last, we report that TCOF1 promotes cellular resistance to DNA damaging agents. Collectively, our findings identify TCOF1 as a DDR factor that could cooperate with ATM and NBS1 to suppress inappropriate rDNA transcription and maintain genomic integrity after DNA damage. PMID:25512513

Hypothesis of the cause and development of neoplasms.

PubMed

Hoang, Ba X; Levine, Stephen A; Pham, Phuong; Shaw, David Graeme

2007-02-01

Cancer, in general, is considered a disease of genetic mutation. Many questions are, however, unanswered. How exactly do mutations occur in the cells? How do gene mutations interface with the cell microenvironment and macroenvironment to create cancer phenotypes? Is mutation the cause of cancer or the consequence of special adaptive responses to aging; hormonal imbalance; physical, chemical and biologic stresses and damage? What makes cancer spread in the body and invade other organs causing death to the patient? In this paper, we hypothesize that the cellular hyperexcitability via stimulation of mineral channels (e.g. sodium voltage-gated channels) and ligand excitatory receptors (e.g. glutamate and other neuron and non-neuronal excitatory receptors) could be a significant causative and pathogenic factor of cancer. Managing hyperexcitatory states of the cells through lifestyle, nutritional changes, phytochemical and pharmaceutical medications theoretically could be a prospective direction in cancer prevention and therapy.

Disrupted iron homeostasis causes dopaminergic neurodegeneration in mice

PubMed Central

Matak, Pavle; Matak, Andrija; Moustafa, Sarah; Aryal, Dipendra K.; Benner, Eric J.; Wetsel, William; Andrews, Nancy C.

2016-01-01

Disrupted brain iron homeostasis is a common feature of neurodegenerative disease. To begin to understand how neuronal iron handling might be involved, we focused on dopaminergic neurons and asked how inactivation of transport proteins affected iron homeostasis in vivo in mice. Loss of the cellular iron exporter, ferroportin, had no apparent consequences. However, loss of transferrin receptor 1, involved in iron uptake, caused neuronal iron deficiency, age-progressive degeneration of a subset of dopaminergic neurons, and motor deficits. There was gradual depletion of dopaminergic projections in the striatum followed by death of dopaminergic neurons in the substantia nigra. Damaged mitochondria accumulated, and gene expression signatures indicated attempted axonal regeneration, a metabolic switch to glycolysis, oxidative stress, and the unfolded protein response. We demonstrate that loss of transferrin receptor 1, but not loss of ferroportin, can cause neurodegeneration in a subset of dopaminergic neurons in mice. PMID:26929359

Effect of lycopene and {beta}-carotene on peroxynitrite-mediated cellular modifications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzandu, Kaampwe; Ishizuka, Mayumi; Sakamoto, Kentaro Q.

2006-09-15

Peroxynitrite formed by the reaction of superoxide and nitric oxide is a highly reactive species with a role in various pathological processes such as cancer, chronic inflammation, and cardiovascular and neurological diseases. In the present study, the effect of the carotenoids, lycopene and {beta}-carotene, on peroxynitrite-mediated modifications in plasmid DNA as well as cellular DNA and proteins were investigated. In pUC18 plasmid DNA, these carotenoids strongly inhibited DNA strand breaks caused by peroxynitrite generated from 3-morpholinosydnonimine (SIN-1). SIN-1 was also used to determine effects on DNA damage and protein tyrosine nitration in Chinese hamster lung fibroblasts. SIN-1 dose-dependently increased nitrationmore » of proteins in cells above basal levels as determined by Western blotting. This nitration was inhibited in the presence of the uric acid as well as lycopene. Physiological concentrations (0.31-10 {mu}M) of lycopene and {beta}-carotene also had protective effects on DNA damage, as measured by the comet assay. Lycopene significantly reduced DNA damage particularly, in the median range of concentrations (2.5 {mu}M). The protective effects of lycopene and {beta}-carotene could be due to their scavenging of reactive oxygen (ROS) and/or nitrogen species (RNS) as they reduce the amount of intracellular ROS/RNS produced following treatment with SIN-1 by as much as 47.5% and 42.4%, respectively. The results obtained in this study suggest that carotenoids may alleviate some of the deleterious effects of peroxynitrite and possibly other reactive nitrogen species as well in vivo.« less

Ascorbic Acid Repletion: A Possible Therapy for Diabetic Macular Edema?

PubMed Central

May, James M.

2016-01-01

Macular edema poses a significant risk for visual loss in persons with diabetic retinopathy. It occurs when plasma constituents and fluid leak out of damaged retinal microvasculature in the area of the macula, causing loss of central vision. Apoptotic loss of pericytes surrounding capillaries is perhaps the earliest feature of diabetic vascular damage in the macula, which is also associated with dysfunction of the endothelium and loss of the otherwise very tight endothelial permeability barrier. Increased oxidative stress is a key feature of damage to both cell types, mediated by excess superoxide from glucose-induced increases in mitochondrial metabolism, as well as by activation of the receptor for advanced glycation end products (RAGE). The latter in turn activates multiple pathways, some of which lead to increased oxidative stress, such as those involving NF-κB, NADPH oxidase, and endothelial nitric oxide synthase. Such cellular oxidative stress is associated with low cellular and plasma ascorbic acid levels in many subjects with diabetes in poor glycemic control. Whether repletion of low ascorbate in retinal endothelium and pericytes might help to prevent diabetic macular edema is unknown. However, cell culture studies show that the vitamin prevents high-glucose and RAGE-induced apoptosis in both cell types, that it preserves nitric oxide generated by endothelial cells, and that it tightens the leaky endothelial permeability barrier. Although these findings need to be confirmed in pre-clinical animal studies, it is worth considering clinical trials to determine whether adequate ascorbate repletion is possible and whether it might help to delay or even reverse early diabetic macular edema. PMID:26898503

Heart Alterations after Domoic Acid Administration in Rats

PubMed Central

Vieira, Andres C.; Cifuentes, José Manuel; Bermúdez, Roberto; Ferreiro, Sara F.; Castro, Albina Román; Botana, Luis M.

2016-01-01

Domoic acid (DA) is one of the best known marine toxins, causative of important neurotoxic alterations. DA effects are documented both in wildlife and experimental assays, showing that this toxin causes severe injuries principally in the hippocampal area. In the present study we have addressed the long-term toxicological effects (30 days) of DA intraperitoneal administration in rats. Different histological techniques were employed in order to study DA toxicity in heart, an organ which has not been thoroughly studied after DA intoxication to date. The presence of DA was detected by immunohistochemical assays, and cellular alterations were observed both by optical and transmission electron microscopy. Although histological staining methods did not provide any observable tissue damage, transmission electron microscopy showed several injuries: a moderate lysis of myofibrils and loss of mitochondrial conformation. This is the first time the association between heart damage and the presence of the toxin has been observed. PMID:26978401

Using quantum filters to process images of diffuse axonal injury

NASA Astrophysics Data System (ADS)

Pineda Osorio, Mateo

2014-06-01

Some images corresponding to a diffuse axonal injury (DAI) are processed using several quantum filters such as Hermite Weibull and Morse. Diffuse axonal injury is a particular, common and severe case of traumatic brain injury (TBI). DAI involves global damage on microscopic scale of brain tissue and causes serious neurologic abnormalities. New imaging techniques provide excellent images showing cellular damages related to DAI. Said images can be processed with quantum filters, which accomplish high resolutions of dendritic and axonal structures both in normal and pathological state. Using the Laplacian operators from the new quantum filters, excellent edge detectors for neurofiber resolution are obtained. Image quantum processing of DAI images is made using computer algebra, specifically Maple. Quantum filter plugins construction is proposed as a future research line, which can incorporated to the ImageJ software package, making its use simpler for medical personnel.

Disintegration of cruciform and G-quadruplex structures during the course of helicase-dependent amplification (HDA).

PubMed

Li, Dawei; Lv, Bei; Zhang, Hao; Lee, Jasmine Yiqin; Li, Tianhu

2015-04-15

Unlike chemical damages on DNA, physical alterations of B-form of DNA occur commonly in organisms that serve as signals for specified cellular events. Although the modes of action for repairing of chemically damaged DNA have been well studied nowadays, the repairing mechanisms for physically altered DNA structures have not yet been understood. Our current in vitro studies show that both breakdown of stable non-B DNA structures and resumption of canonical B-conformation of DNA can take place during the courses of isothermal helicase-dependent amplification (HDA). The pathway that makes the non-B DNA structures repairable is presumably the relieving of the accumulated torsional stress that was caused by the positive supercoiling. Our new findings suggest that living organisms might have evolved this distinct and economical pathway for repairing their physically altered DNA structures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Study of the Effects of Ultrasonic Waves on the Reproductive Integrity of Mammalian Cells Cultured in Vitro

NASA Technical Reports Server (NTRS)

Martins, B. I.

1971-01-01

The effects of monochromatic ultrasonic waves of 0.1, 0.5, 1.0, 2.0 and, 3.3 MHz frequency on the colony-forming ability of mammalian cells (M3-1,V79, Chang's and T-1) cultured in vitro have been studied to determine the nature of the action of ultrasonic energy on biological systems at the cellular level. The combined effect of ultrasound and X-rays has also been studied. It is concluded: (1) Ultrasonic irradiation causes both lethal and sublethal damage. (2) There is a threshold dose rate for lethal effects. (3) The effectiveness of ultrasonic waves in causing cell death probably depends on the frequency and the amplitude of the waves for a given cell line, indicating a possible resonance phenomenon.

The pathogenesis of measles.

PubMed

de Vries, Rory D; Mesman, Annelies W; Geijtenbeek, Teunis B H; Duprex, W Paul; de Swart, Rik L

2012-06-01

Measles is an important cause of childhood morbidity and mortality in developing countries. Measles virus (MV) is transmitted via the respiratory route and causes systemic disease. Over the last decade, identification of new cellular receptors and studies in animal models have challenged the historic concepts of measles pathogenesis. It is thought that MV enters the host by infection of alveolar macrophages and/or dendritic cells in the airways, and is amplified in local lymphoid tissues. Viremia mediated by infected CD150+ lymphocytes results in systemic dissemination. Infection of lymphocytes and dendritic cells in the respiratory submucosa facilitates basolateral infection of epithelial cells via the newly identified receptor Nectin-4. Concomitant and extensive epithelial damage may contribute to efficient transmission to the next host. Copyright © 2012 Elsevier B.V. All rights reserved.

Human cytomegalovirus inhibits a DNA damage response by mislocalizing checkpoint proteins

NASA Astrophysics Data System (ADS)

Gaspar, Miguel; Shenk, Thomas

2006-02-01

The DNA damage checkpoint pathway responds to DNA damage and induces a cell cycle arrest to allow time for DNA repair. Several viruses are known to activate or modulate this cellular response. Here we show that the ataxia-telangiectasia mutated checkpoint pathway, which responds to double-strand breaks in DNA, is activated in response to human cytomegalovirus DNA replication. However, this activation does not propagate through the pathway; it is blocked at the level of the effector kinase, checkpoint kinase 2 (Chk2). Late after infection, several checkpoint proteins, including ataxia-telangiectasia mutated and Chk2, are mislocalized to a cytoplasmic virus assembly zone, where they are colocalized with virion structural proteins. This colocalization was confirmed by immunoprecipitation of virion proteins with an antibody that recognizes Chk2. Virus replication was resistant to ionizing radiation, which causes double-strand breaks in DNA. We propose that human CMV DNA replication activates the checkpoint response to DNA double-strand breaks, and the virus responds by altering the localization of checkpoint proteins to the cytoplasm and thereby inhibiting the signaling pathway. ionizing radiation | ataxia-telangiectasia mutated pathway

Thermal injury models for optical treatment of biological tissues: a comparative study.

PubMed

Fanjul-Velez, Felix; Ortega-Quijano, Noe; Salas-Garcia, Irene; Arce-Diego, Jose L

2010-01-01

The interaction of optical radiation with biological tissues causes an increase in the temperature that, depending on its magnitude, can provoke a thermal injury process in the tissue. The establishment of laser irradiation pathological limits constitutes an essential task, as long as it enables to fix and delimit a range of parameters that ensure a safe treatment in laser therapies. These limits can be appropriately described by kinetic models of the damage processes. In this work, we present and compare several models for the study of thermal injury in biological tissues under optical illumination, particularly the Arrhenius thermal damage model and the thermal dosimetry model based on CEM (Cumulative Equivalent Minutes) 43°C. The basic concepts that link the temperature and exposition time with the tissue injury or cellular death are presented, and it will be shown that they enable to establish predictive models for the thermal damage in laser therapies. The results obtained by both models will be compared and discussed, highlighting the main advantages of each one and proposing the most adequate one for optical treatment of biological tissues.

Base excision repair, the redox environment and therapeutic implications.

PubMed

Storr, S J; Woolston, C M; Martin, S G

2012-01-01

Control of redox homeostasis is crucial for a number of cellular processes with deregulation leading to a number of serious consequences including oxidative damage such induction of DNA base lesions. The DNA lesions caused by oxidative damage are principally repaired by the base excision repair (BER) pathway. Pharmacological inhibition of BER is becoming an increasingly active area of research with the emergence of PARP inhibitors in cancer therapy. The redox status of the cell is modulated by a number of systems, including a large number of anti-oxidant enzymes who function in the control of superoxide and hydrogen peroxide, and ultimately in the release of the damaging hydroxyl radical. Here we provide an overview of reactive oxygen species (ROS) production and its modulation by antioxidant enzymes. The review also discusses the effect of ROS on the BER pathway, particularly in relation to cancer. Finally, as the modulation of the redox environment is of interest in cancer therapy, with certain agents having the potential to reverse chemo- and radiotherapy resistance or treat therapy related toxicity, we discuss redox modulating agents currently under development.

3-NP-induced Huntington's-like disease impairs Nrf2 activation without loss of cardiac function in aged rats.

PubMed

Silva-Palacios, A; Ostolga-Chavarría, M; Buelna-Chontal, M; Garibay, C; Hernández-Reséndiz, S; Roldán, F J; Flores, P L; Luna-López, A; Königsberg, M; Zazueta, C

2017-10-01

Cardiovascular diseases (CVDs) are one of the leading causes of death in patients over 60years with Huntington's disease (HD). Here, we investigated if age-related oxidative stress (OS) is a relevant factor to develop cardiac damage in an in vivo model of striatal neurodegeneration induced by 3-nitropropionic acid (3-NP). We also evaluated the potential effect of tert-butylhydroquinone (tBHQ) to increase the Nrf2-regulated antioxidant response in hearts from adult and aged rats intoxicated with 3-NP. Our results showed that 3-NP-treatment did not induce cardiac dysfunction, neither in adult nor in aged rats. However, at the cellular level, adult animals showed higher susceptibility to 3-NP-induced damage than aged rats, which suggest that chronic oxidative stress ongoing during aging might have induced an hormetic response that probably prevented from further 3-NP damage. We also found that the oxidative unbalance concurs with unresponsiveness of the Nrf2-mediated antioxidant response in old animals. Copyright © 2017 Elsevier Inc. All rights reserved.

Replication-mediated disassociation of replication protein A-XPA complex upon DNA damage: implications for RPA handing off.

PubMed

Jiang, Gaofeng; Zou, Yue; Wu, Xiaoming

2012-08-01

RPA (replication protein A), the eukaryotic ssDNA (single-stranded DNA)-binding protein, participates in most cellular processes in response to genotoxic insults, such as NER (nucleotide excision repair), DNA, DSB (double-strand break) repair and activation of cell cycle checkpoint signalling. RPA interacts with XPA (xeroderma pigmentosum A) and functions in early stage of NER. We have shown that in cells the RPA-XPA complex disassociated upon exposure of cells to high dose of UV irradiation. The dissociation required replication stress and was partially attributed to tRPA hyperphosphorylation. Treatment of cells with CPT (camptothecin) and HU (hydroxyurea), which cause DSB DNA damage and replication fork collapse respectively and also leads to the disruption of RPA-XPA complex. Purified RPA and XPA were unable to form complex in vitro in the presence of ssDNA. We propose that the competition-based RPA switch among different DNA metabolic pathways regulates the dissociation of RPA with XPA in cells after DNA damage. The biological significances of RPA-XPA complex disruption in relation with checkpoint activation, DSB repair and RPA hyperphosphorylation are discussed.

TRF2 and apollo cooperate with topoisomerase 2alpha to protect human telomeres from replicative damage.

PubMed

Ye, Jing; Lenain, Christelle; Bauwens, Serge; Rizzo, Angela; Saint-Léger, Adelaïde; Poulet, Anaïs; Benarroch, Delphine; Magdinier, Frédérique; Morere, Julia; Amiard, Simon; Verhoeyen, Els; Britton, Sébastien; Calsou, Patrick; Salles, Bernard; Bizard, Anna; Nadal, Marc; Salvati, Erica; Sabatier, Laure; Wu, Yunlin; Biroccio, Annamaria; Londoño-Vallejo, Arturo; Giraud-Panis, Marie-Josèphe; Gilson, Eric

2010-07-23

Human telomeres are protected from DNA damage by a nucleoprotein complex that includes the repeat-binding factor TRF2. Here, we report that TRF2 regulates the 5' exonuclease activity of its binding partner, Apollo, a member of the metallo-beta-lactamase family that is required for telomere integrity during S phase. TRF2 and Apollo also suppress damage to engineered interstitial telomere repeat tracts that were inserted far away from chromosome ends. Genetic data indicate that DNA topoisomerase 2alpha acts in the same pathway of telomere protection as TRF2 and Apollo. Moreover, TRF2, which binds preferentially to positively supercoiled DNA substrates, together with Apollo, negatively regulates the amount of TOP1, TOP2alpha, and TOP2beta at telomeres. Our data are consistent with a model in which TRF2 and Apollo relieve topological stress during telomere replication. Our work also suggests that cellular senescence may be caused by topological problems that occur during the replication of the inner portion of telomeres. Copyright 2010 Elsevier Inc. All rights reserved.

The role of the antioxidant system during intense endurance exercise: lessons from migrating birds.

PubMed

Cooper-Mullin, Clara; McWilliams, Scott R

2016-12-01

During migration, birds substantially increase their metabolic rate and burn fats as fuel and yet somehow avoid succumbing to overwhelming oxidative damage. The physiological means by which vertebrates such as migrating birds can counteract an increased production of reactive species (RS) are rather limited: they can upregulate their endogenous antioxidant system and/or consume dietary antioxidants (prophylactically or therapeutically). Thus, birds can alter different components of their antioxidant system to respond to the demands of long-duration flights, but much remains to be discovered about the complexities of RS production and antioxidant protection throughout migration. Here, we use bird migration as an example to discuss how RS are produced during endurance exercise and how the complex antioxidant system can protect against cellular damage caused by RS. Understanding how a bird's antioxidant system responds during migration can lend insights into how antioxidants protect birds during other life-history stages when metabolic rate may be high, and how antioxidants protect other vertebrates from oxidative damage during endurance exercise. © 2016. Published by The Company of Biologists Ltd.

Pycnogenol (PYC) induces apoptosis in human fibrosarcoma (HFS) cells under metal-mediated oxidative stress.

PubMed

Park, Yeon Sun; Kim, Young Gon

2011-01-01

Pycnogenol (PYC), polyphenolic compounds with antioxidant activity, acted as a prooxidant. PYC caused oxidative stress in human fibrosarcoma cells (HFS) when administered following pretreatment with iron chloride. The generated reactive oxygen species (ROS) caused the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in DNA and resulted in more apoptosis in HFS cells than in the human fibroblastoma (HFB) cells. DNA damage and cellular viability at different PYC concentrations were closely consistent with cell growth, high performance liquid chromatography (HPLC), Enzyme Linked Immunosorbent Assay (ELISA) and assays of two major antioxidant enzymes, superoxide dismutase (SOD) and catalase. Although the presence of PYC induced total SOD and catalase activities under oxidative stress in dose dependent fashion, more apoptotic cells were induced in HFS cells with increased [8-OHdG] than in HFB cells. The results suggest that PYC selectively induced cell death in HFS cells. This further confirmed that PYC-induced apoptosis is mediated primarily through the activation of caspase-3 apoptotic marker in HFS cells but not in HFB cells. We conclude that PYC would behave as either antioxidant or prooxidant dependant upon the cellular types.

Mitochondria and heart failure.

PubMed

Murray, Andrew J; Edwards, Lindsay M; Clarke, Kieran

2007-11-01

Energetic abnormalities in cardiac and skeletal muscle occur in heart failure and correlate with clinical symptoms and mortality. It is likely that the cellular mechanism leading to energetic failure involves mitochondrial dysfunction. Therefore, it is crucial to elucidate the causes of mitochondrial myopathy, in order to improve cardiac and skeletal muscle function, and hence quality of life, in heart failure patients. Recent studies identified several potential stresses that lead to mitochondrial dysfunction in heart failure. Chronically elevated plasma free fatty acid levels in heart failure are associated with decreased metabolic efficiency and cellular insulin resistance. Tissue hypoxia, resulting from low cardiac output and endothelial impairment, can lead to oxidative stress and mitochondrial DNA damage, which in turn causes dysfunction and loss of mitochondrial mass. Therapies aimed at protecting mitochondrial function have shown promise in patients and animal models with heart failure. Despite current therapies, which provide substantial benefit to patients, heart failure remains a relentlessly progressive disease, and new approaches to treatment are necessary. Novel pharmacological agents are needed that optimize substrate metabolism and maintain mitochondrial integrity, improve oxidative capacity in heart and skeletal muscle, and alleviate many of the clinical symptoms associated with heart failure.

Targeting Neutrophilic Inflammation Using Polymersome-Mediated Cellular Delivery.

PubMed

Robertson, James D; Ward, Jon R; Avila-Olias, Milagros; Battaglia, Giuseppe; Renshaw, Stephen A

2017-05-01

Neutrophils are key effector cells in inflammation and play an important role in neutralizing invading pathogens. During inflammation resolution, neutrophils undergo apoptosis before they are removed by macrophages, but if apoptosis is delayed, neutrophils can cause extensive tissue damage and chronic disease. Promotion of neutrophil apoptosis is a potential therapeutic approach for treating persistent inflammation, yet neutrophils have proven difficult cells to manipulate experimentally. In this study, we deliver therapeutic compounds to neutrophils using biocompatible, nanometer-sized synthetic vesicles, or polymersomes, which are internalized by binding to scavenger receptors and subsequently escape the early endosome through a pH-triggered disassembly mechanism. This allows polymersomes to deliver molecules into the cell cytosol of neutrophils without causing cellular activation. After optimizing polymersome size, we show that polymersomes can deliver the cyclin-dependent kinase inhibitor (R)-roscovitine into human neutrophils to promote apoptosis in vitro. Finally, using a transgenic zebrafish model, we show that encapsulated (R)-roscovitine can speed up inflammation resolution in vivo more efficiently than the free drug. These results show that polymersomes are effective intracellular carriers for drug delivery into neutrophils. This has important consequences for the study of neutrophil biology and the development of neutrophil-targeted therapeutics. Copyright © 2017 The Authors.

The Molecular Origin of the MMR-dependent Apoptosis Pathway from Dynamics Analysis of MutSα-DNA Complexes

PubMed Central

Negureanu, Lacramioara; Salsbury, Freddie R.

2012-01-01

The cellular response to DNA damage signaling by MMR proteins is incompletely understood. It is generally accepted that MMR-dependent apoptosis pathway in response to DNA damage detection is independent of MMR's DNA repair function. In this study we investigate correlated motions in response to the binding of mismatched and PCL DNA fragments by MutSα, as derived from 50 ns molecular dynamics simulations. The protein dynamics in response to the mismatched and damaged DNA recognition suggests that MutSα signals their recognition through independent pathways providing evidence for the molecular origin of the MMR-dependent apoptosis. MSH2 subunit is indicated to play a key role in signaling both mismatched and damaged DNA recognition; localized and collective motions within the protein allow identifying sites on the MSH2 surface possible involved in recruiting proteins responsible for downstream events. Unlike in the mismatch complex, predicted key communication sites specific for the damage recognition are on the list of known cancer causing mutations or deletions. This confirms MSH2's role in signaling DNA-damage induced apoptosis and suggests that defects in MMR alone is sufficient to trigger tumorigenesis, supporting the experimental evidence that MMR-damage response function could protect from the early occurrence of tumors. Identifying these particular communication sites may have implications for the treatment of cancers that are not defective for MMR, but are unable to function optimally for MMR-dependent responses following DNA damage such as the case of resistance to cisplatin. PMID:22712459

Formation of Clustered DNA Damage after High-LET Irradiation: A Review

NASA Technical Reports Server (NTRS)

Hada, Megumi; Georgakilas, Alexandros G.

2008-01-01

Radiation can cause as well as cure cancer. The risk of developing radiation-induced cancer has traditionally been estimated from cancer incidence among survivors of the atomic bombs in Hiroshima and Nagasaki. These data provide the best estimate of human cancer risk over the dose range for low linear energy transfer (LET) radiations, such as X- or gamma-rays. The situation of estimating the real biological effects becomes even more difficult in the case of high LET particles encountered in space or as the result of domestic exposure to particles from radon gas emitters or other radioactive emitters like uranium-238. Complex DNA damage, i.e., the signature of high-LET radiations comprises by closely spaced DNA lesions forming a cluster of DNA damage. The two basic groups of complex DNA damage are double strand breaks (DSBs) and non-DSB oxidative clustered DNA lesions (OCDL). Theoretical analysis and experimental evidence suggest there is increased complexity and severity of complex DNA damage with increasing LET (linear energy transfer) and a high mutagenic or carcinogenic potential. Data available on the formation of clustered DNA damage (DSBs and OCDL) by high-LET radiations are often controversial suggesting a variable response to dose and type of radiation. The chemical nature and cellular repair mechanisms of complex DNA damage have been much less characterized than those of isolated DNA lesions like an oxidized base or a single strand break especially in the case of high-LET radiation. This review will focus on the induction of clustered DNA damage by high-LET radiations presenting the earlier and recent relative data.

DNA Repair Deficiency in Neurodegeneration

PubMed Central

Jeppesen, Dennis Kjølhede; Bohr, Vilhelm A.; Stevnsner, Tinna

2011-01-01

Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative base lesions is base excision repair, and such repair is crucial for neurons given their high rates of oxygen metabolism. Mismatch repair corrects base mispairs generated during replication and evidence indicates that oxidative DNA damage can cause this pathway to expand trinucleotide repeats, thereby causing Huntington’s disease. Single-strand breaks are common DNA lesions and are associated with the neurodegenerative diseases, ataxia-oculomotor apraxia-1 and spinocerebellar ataxia with axonal neuropathy-1. DNA double-strand breaks are toxic lesions and two main pathways exist for their repair: homologous recombination and non-homologous end-joining. Ataxia telangiectasia and related disorders with defects in these pathways illustrate that such defects can lead to early childhood neurodegeneration. Aging is a risk factor for neurodegeneration and accumulation of oxidative mitochondrial DNA damage may be linked with the age-associated neurodegenerative disorders Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Mutation in the WRN protein leads to the premature aging disease Werner syndrome, a disorder that features neurodegeneration. In this article we review the evidence linking deficiencies in the DNA repair pathways with neurodegeneration. PMID:21550379

Functional characterization of two SOS-regulated genes involved in mitomycin C resistance in Caulobacter crescentus.

PubMed

Lopes-Kulishev, Carina O; Alves, Ingrid R; Valencia, Estela Y; Pidhirnyj, María I; Fernández-Silva, Frank S; Rodrigues, Ticiane R; Guzzo, Cristiane R; Galhardo, Rodrigo S

2015-09-01

The SOS response is a universal bacterial regulon involved in the cellular response to DNA damage and other forms of stress. In Caulobacter crescentus, previous work has identified a plethora of genes that are part of the SOS regulon, but the biological roles of several of them remain to be determined. In this study, we report that two genes, hereafter named mmcA and mmcB, are involved in the defense against DNA damage caused by mitomycin C (MMC), but not against lesions induced by other common DNA damaging agents, such as UVC light, methyl methanesulfonate (MMS) and hydrogen peroxide. mmcA is a conserved gene that encodes a member of the glyoxalases/dioxygenases protein family, and acts independently of known DNA repair pathways. On the other hand, epistasis analysis showed that mmcB acts in the same pathway as imuC (dnaE2), and is required specifically for MMC-induced mutagenesis, but not for that induced by UV light, suggesting a role for MmcB in translesion synthesis-dependent repair of MMC damage. We show that the lack of MMC-induced mutability in the mmcB strain is not caused by lack of proper SOS induction of the imuABC operon, involved in translesion synthesis (TLS) in C. crescentus. Based on this data and on structural analysis of a close homolog, we propose that MmcB is an endonuclease which creates substrates for ImuABC-mediated TLS patches. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of lemon verbena supplementation on muscular damage markers, proinflammatory cytokines release and neutrophils' oxidative stress in chronic exercise.

PubMed

Funes, Lorena; Carrera-Quintanar, Lucrecia; Cerdán-Calero, Manuela; Ferrer, Miguel D; Drobnic, Franchek; Pons, Antoni; Roche, Enrique; Micol, Vicente

2011-04-01

Intense exercise is directly related to muscular damage and oxidative stress due to excessive reactive oxygen species (ROS) in both, plasma and white blood cells. Nevertheless, exercise-derived ROS are essential to regulate cellular adaptation to exercise. Studies on antioxidant supplements have provided controversial results. The purpose of this study was to determine the effect of moderate antioxidant supplementation (lemon verbena extract) in healthy male volunteers that followed a 90-min running eccentric exercise protocol for 21 days. Antioxidant enzymes activities and oxidative stress markers were measured in neutrophils. Besides, inflammatory cytokines and muscular damage were determined in whole blood and serum samples, respectively. Intense running exercise for 21 days induced antioxidant response in neutrophils of trained male through the increase of the antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase. Supplementation with moderate levels of an antioxidant lemon verbena extract did not block this cellular adaptive response and also reduced exercise-induced oxidative damage of proteins and lipids in neutrophils and decreased myeloperoxidase activity. Moreover, lemon verbena supplementation maintained or decreased the level of serum transaminases activity indicating a protection of muscular tissue. Exercise induced a decrease of interleukin-6 and interleukin-1β levels after 21 days measured in basal conditions, which was not inhibited by antioxidant supplementation. Therefore, moderate antioxidant supplementation with lemon verbena extract protects neutrophils against oxidative damage, decreases the signs of muscular damage in chronic running exercise without blocking the cellular adaptation to exercise.

The Effects of Transient Retinal Detachment on Cavity Size and Glial and Neural Remodeling in a Mouse Model of X-Linked Retinoschisis

PubMed Central

Luna, Gabriel; Kjellstrom, Sten; Verardo, Mark R.; Lewis, Geoffrey P.; Byun, Jiyun; Sieving, Paul A.; Fisher, Steven K.

2009-01-01

Purpose To determine the cellular consequences of retinal detachment in retinoschisin knockout (Rs1-KO) mice, a model for retinoschisin in humans. Methods Experimental retinal detachments (RDs) were induced in the right eyes of both Rs1-KO and wild-type (wt) control mice. Immunocytochemistry was performed on retinal tissue at 1, 7, or 28 days after RD with antibodies to anti-GFAP, -neurofilament, and -rod opsin to examine cellular changes after detachment. Images of the immunostained tissue were captured by laser scanning confocal microscopy. Quantitative analysis was performed to measure the number of Hoechst-stained photoreceptor nuclei and their density, number, and size of inner retinal cavities, as well as the number of subretinal glial scars. Results Since detachments were created with balanced salt solution, by examination, all retinas had spontaneously reattached by 1 day. Cellular responses common to many photoreceptor degenerations occurred in the nondetached retinas of Rs1-KO mice, and, of importance, RD did not appear to significantly accentuate these responses. The number of schisis cavities was not changed after detachment, but their size was reduced. Conclusions These data indicate that large short-term RD in Rs1-KO mice, followed by a period of reattachment may cause a slight increase in photoreceptor cell death, but detachments do not accentuate the gliosis and neurite sprouting already present and may in fact reduce the size of existing retinal cavities. This finding suggests that performing subretinal injections to deliver therapeutic agents may be a viable option in the treatment of patients with retinoschisis without causing significant cellular damage to the retina. PMID:19387072

Cellular characterization of compression-induceddamage in live biological samples

NASA Astrophysics Data System (ADS)

Bo, Chiara; Balzer, Jens; Hahnel, Mark; Rankin, Sara M.; Brown, Katherine A.; Proud, William

2012-03-01

Understanding the damage that high intensity compression waves induce in human tissues is critical for developing improved therapies for patients suffering from blast injuries. Experimentally based models of blast injury using live biological samples are needed. In this study we have developed a system to directly assess the effects of dynamic loading conditions on live cells. Here, we describe a confinement chamber designed to subject live cell cultures in a liquid environment to high intensity compression waves using a split Hopkinson pressure bar system. Signals from the strain gauges mounted on the bars and the chamber allow the measurement of parameters such as pressure and duration of the stimulus. The chamber itself also allows recovery of cells subjected to compression for assessment of cellular damage. In these studies we present evidence of increased levels of damage and loss of cellular integrity in cultured mouse mesenchymal stem cells subjected to a high-intensity compression wave with a peak pressure of 7.6 ± 0.8 MPa.

Atrial fibrillation in the elderly: the potential contribution of reactive oxygen species

PubMed Central

Schillinger, Kurt J.; Patel, Vickas V.

2012-01-01

Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia, and is a significant source of healthcare expenditures throughout the world. It is an arrhythmia with a very clearly defined predisposition for individuals of advanced age, and this fact has led to intense study of the mechanistic links between aging and AF. By promoting oxidative damage to multiple subcellular and cellular structures, reactive oxygen species (ROS) have been shown to induce the intra- and extra-cellular changes necessary to promote the pathogenesis of AF. In addition, the generation and accumulation of ROS have been intimately linked to the cellular processes which underlie aging. This review begins with an overview of AF pathophysiology, and introduces the critical structures which, when damaged, predispose an otherwise healthy atrium to AF. The available evidence that ROS can lead to damage of these critical structures is then reviewed. Finally, the evidence linking the process of aging to the pathogenesis of AF is discussed. PMID:23341843

Crosstalk between the nucleolus and the DNA damage response.

PubMed

Ogawa, L M; Baserga, S J

2017-02-28

Nucleolar function and the cellular response to DNA damage have long been studied as distinct disciplines. New research and a new appreciation for proteins holding multiple functional roles, however, is beginning to change the way we think about the crosstalk among distinct cellular processes. Here, we focus on the crosstalk between the DNA damage response and the nucleolus, including a comprehensive review of the literature that reveals a role for conventional DNA repair proteins in ribosome biogenesis, and conversely, ribosome biogenesis proteins in DNA repair. Furthermore, with recent advances in nucleolar proteomics and a growing list of proteins that localize to the nucleolus, it is likely that we will continue to identify new DNA repair proteins with a nucleolar-specific role. Given the importance of ribosome biogenesis and DNA repair in essential cellular processes and the role that they play in diverse pathologies, continued elucidation of the overlap between these two disciplines will be essential to the advancement of both fields and to the development of novel therapeutics.

Accumulation of senescent cells in mitotic tissue of aging primates.

PubMed

Jeyapalan, Jessie C; Ferreira, Mark; Sedivy, John M; Herbig, Utz

2007-01-01

Cellular senescence, a stress induced growth arrest of somatic cells, was first documented in cell cultures over 40 years ago, however its physiological significance has only recently been demonstrated. Using novel biomarkers of cellular senescence we examined whether senescent cells accumulate in tissues from baboons of ages encompassing the entire lifespan of this species. We show that dermal fibroblasts, displaying markers of senescence such as telomere damage, active checkpoint kinase ATM, high levels of heterochromatin proteins and elevated levels of p16, accumulate in skin biopsies from baboons with advancing age. The number of dermal fibroblasts containing damaged telomeres reaches a value of over 15% of total fibroblasts, whereas 80% of cells contain high levels of the heterochromatin protein HIRA. In skeletal muscle, a postmitotic tissue, only a small percentage of myonuclei containing damaged telomeres were detected regardless of animal age. The presence of senescent cells in mitotic tissues might therefore be a contributing factor to aging and age related pathology and provides further evidence that cellular senescence is a physiological event.

Oxygen toxicity.

PubMed

Stogner, S W; Payne, D K

1992-12-01

The objective of this article is to provide an overview of the biochemistry of oxygen metabolism, including the formation of free radicals and the role of endogenous antioxidants. Pathophysiologic correlates underlying the clinical manifestations of oxygen toxicity are reviewed and management strategies are outlined. References from basic science and clinical journals were selected from the authors' files and from a search of a computerized database of the biomedical literature. Articles selected for review included both historical and current literature concerning the biochemistry and pathophysiology of oxygen toxicity in animals and humans. The benefits of oxygen therapy have been known for many years; however, its potential toxicity has not been recognized until the last two decades. The lungs, the eyes, and, under certain conditions, the central nervous system are the organs most affected by prolonged exposure to hyperoxic environments. Free radical formation during cellular metabolism under hyperoxic conditions is recognized as the biochemical basis of oxygen injury to cells and organs. Endogenous antioxidants are a primary means of detoxifying reactive oxygen species and preventing hyperoxia-induced cellular damage. When this defense fails or is overwhelmed by the excessive production of hyperoxia-induced free-radical species, distinctive morphologic changes occur at the cellular level. The amount of hyperoxia required to cause cellular damage and the time course of these changes vary from species to species and from individual to individual within the same species. Age, nutritional status, presence of underlying diseases, and certain drugs may influence the development of oxygen toxicity. There is currently no reliably effective drug for preventing or delaying the development of oxygen toxicity in humans. Use of the lowest effective oxygen concentration, the avoidance of certain drugs, and attention to nutritional and metabolic factors remain the best means currently available to avoid or minimize oxygen toxicity. Research is continuing into more effective ways to prevent, diagnose, and treat this disorder.

Effect of patchouli alcohol on the regulation of heat shock-induced oxidative stress in IEC-6 cells.

PubMed

Liu, Xiaoxi; Jiang, Linshu; Liu, Fenghua; Chen, Yuping; Xu, Lei; Li, Deyin; Ma, Yunfei; Li, Huanrong; Xu, Jianqin

2016-08-01

Purpose Patchouli alcohol (PA) is used to treat gastrointestinal dysfunction. The purpose of this study was to ascertain the function of PA in the regulated process of oxidative stress in rat intestinal epithelial cells (IEC-6). Materials and methods Oxidative stress was stimulated by exposing IEC-6 cells to heat shock (42 °C for 3 h). IEC-6 cells in treatment groups were pretreated with various concentrations of PA (10, 40, and 80 ng/mL) for 3 h before heat shock. Results Heat shock caused damage to the morphology of IEC-6 cells, and increased reactive oxygen species (ROS) level and malondialdehyde (MDA) content. Moreover, mRNA and protein expression by target genes related to oxidative stress in heat shock were also altered. Specifically, the mRNA expression by HSP70, HSP90, GSH-px, NRF2 nd HO-1were all increased, and Nrf2 and Keap1 protein expression were increased after heat shock. However, pretreatment with PA weakened the level of damage to the cellular morphology, and decreased the MDA content caused by heat shock, indicating PA had cytoprotective activities. Pretreatment with PA at high dose significantly increased generation of intracellular ROS. Compared with the heat shock group alone, PA pretreatment significantly decreased the mRNA expression by HSP70, HSP90, SOD, CAT, GSH-px, KEAP1 and HO-1. Furthermore, the high dose of PA significantly increased Nrf2 protein expression, while both the intermediate and high dose of PA significantly increased HO-1 protein expression. Conclusion Heat-shock-induced oxidative stress in IEC-6 cells, and PA could alleviate the Nrf2-Keap1 cellular oxidative stress responses.

Lipid composition affects the rate of photosensitized dissipation of cross-membrane diffusion potential on liposomes

PubMed Central

Ytzhak, Shany; Wuskell, Joseph P.; Loew, Leslie M.; Ehrenberg, Benjamin

2010-01-01

Hydrophobic or amphiphilic tetrapyrrole sensitizers are taken up by cells and are usually located in cellular lipid membranes. Singlet oxygen is photogenerated by the sensitizer and it diffuses in the membrane and causes oxidative damage to membrane components. This damage can occur to membrane lipids and to membrane-localized proteins. Depolarization of the Nernst electric potential on cells’ membranes has been observed in cellular photosensitization, but it was not established whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells’ membranes and to their death. In this work we studied the effect of liposomes’ lipid composition on the kinetics of hematoporphyrin-photosensitized dissipation of K+-diffusion electric potential that was generated across the membranes. We employed an electrochromic voltage-sensitive spectroscopic probe that possesses a high fluorescence signal response to the potential. We found a correlation between the structure and unsaturation of lipids and the leakage of the membrane, following photosensitization. As the extent of non-conjugated unsaturation of the lipids is increased from 1 to 6 double bonds, the kinetics of depolarization become faster. We also found that the kinetics of depolarization is affected by the percentage of the unsaturated lipids in the liposome: as the fraction of the unsaturated lipids increases the leakage trough the membrane is enhanced. When liposomes are composed of a lipid mixture similar to that of natural membranes and photosensitization is being carried out under usual photodynamic therapy (PDT) conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which would have been a mechanism that leads to cell death. PMID:20536150

The regulation of cellular apoptosis by the ROS-triggered PERK/EIF2α/chop pathway plays a vital role in bisphenol A-induced male reproductive toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin, Li

Bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA) is ubiquitous in the environment, wildlife, and humans. Evidence from past studies suggests that BPA is associated with decreased semen quality. However, the molecular basis for the adverse effect of BPA on male reproductive toxicity remains unclear. We evaluated the effect of BPA on mouse spermatocytes GC-2 cells and adult mice, and we explored the potential mechanism of its action. The results showed that BPA inhibited cell proliferation and increased the apoptosis rate. The testes from BPA-treated mice showed fewer spermatogenic cells and sperm in the seminiferous tubules. In addition, BPA caused reactive oxygen species (ROS)more » accumulation. Previous study has verified that mitochondrion was the organelle affected by the BPA-triggered ROS accumulation. We found that BPA induced damage to the endoplasmic reticulum (ER) in addition to mitochondria, and most ER stress-related proteins were activated in cellular and animal models. Knocking down of the PERK/EIF2α/chop pathway, one of the ER stress pathways, partially recovered the BPA-induced cell apoptosis. In addition, an ROS scavenger attenuated the expression of the PERK/EIF2α/chop pathway-related proteins. Taken together, these data suggested that the ROS regulated PERK/EIF2α/chop pathway played a vital role in BPA-induced male reproductive toxicity. - Highlights: • BPA exposure caused the damage of the endoplasmic reticulum. • BPA exposure activated ER stress related proteins in male reproductive system. • ROS regulated PERK/EIF2α/chop pathway played a vital role in BPA-induced toxicity.« less

Advances in Bone Marrow Stem Cell Therapy for Retinal Dysfunction

PubMed Central

Park, Susanna S.; Moisseiev, Elad; Bauer, Gerhard; Anderson, Johnathon D.; Grant, Maria B.; Zam, Azhar; Zawadzki, Robert J.; Werner, John S.; Nolta, Jan A.

2016-01-01

The most common cause of untreatable vision loss is dysfunction of the retina. Conditions, such as age-related macular degeneration, diabetic retinopathy and glaucoma remain leading causes of untreatable blindness worldwide. Various stem cell approaches are being explored for treatment of retinal regeneration. The rationale for using bone marrow stem cells to treat retinal dysfunction is based on preclinical evidence showing that bone marrow stem cells can rescue degenerating and ischemic retina. These stem cells have primarily paracrine trophic effects although some cells can directly incorporate into damaged tissue. Since the paracrine trophic effects can have regenerative effects on multiple cells in the retina, the use of this cell therapy is not limited to a particular retinal condition. Autologous bone marrow-derived stem cells are being explored in early clinical trials as therapy for various retinal conditions. These bone marrow stem cells include mesenchymal stem cells, mononuclear cells and CD34+ cells. Autologous therapy requires no systemic immunosuppression or donor matching. Intravitreal delivery of CD34+ cells and mononuclear cells appears to be tolerated and is being explored since some of these cells can home into the damaged retina after intravitreal administration. The safety of intravitreal delivery of mesenchymal stem cells has not been well established. This review provides an update of the current evidence in support of the use of bone marrow stem cells as treatment for retinal dysfunction. The potential limitations and complications of using certain forms of bone marrow stem cells as therapy are discussed. Future directions of research include methods to optimize the therapeutic potential of these stem cells, non-cellular alternatives using extracellular vesicles, and in vivo high-resolution retinal imaging to detect cellular changes in the retina following cell therapy. PMID:27784628

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Yoo-Shin; Lee, Tae Hoon; O'Neill, Brian E., E-mail: BEOneill@houstonmethodist.org

Non-lethal hyperthermia is used clinically as adjuvant treatment to radiation, with mixed results. Denaturation of protein during hyperthermia treatment is expected to synergize with radiation damage to cause cell cycle arrest and apoptosis. Alternatively, hyperthermia is known to cause tissue level changes in blood flow, increasing the oxygenation and radiosensitivity of often hypoxic tumors. In this study, we elucidate a third possibility, that hyperthermia alters cellular adhesion and mechanotransduction, with particular impact on the cancer stem cell population. We demonstrate that cell heating results in a robust but temporary loss of cancer cell aggressiveness and metastatic potential in mouse models.more » In vitro, this heating results in a temporary loss in cell mobility, adhesion, and proliferation. Our hypothesis is that the loss of cellular adhesion results in suppression of cancer stem cells and loss of tumor virulence and metastatic potential. Our study suggests that the metastatic potential of cancer is particularly reduced by the effects of heat on cellular adhesion and mechanotransduction. If true, this could help explain both the successes and failures of clinical hyperthermia, and suggest ways to target treatments to those who would most benefit. - Highlights: • Non-lethal hyperthermia treatment of cancer cells is shown to cause a reduction in rates of tumor initiation and metastasis. • Dynamic imaging of cells during heat treatment shows temporary changes in cell shape, cell migration, and cell proliferation. • Loss of adhesion may lead to the observed effect, which may disproportionately impact the tumor initiating cell fraction. • Loss or suppression of the tumor initiating cell fraction results in the observed loss of metastatic potential in vivo. • This result may lead to new approaches to synergizing hyperthermia with surgery, radiation, and chemotherapy.« less

Role of NADP+-dependent isocitrate dehydrogenase (NADP+-ICDH) on cellular defence against oxidative injury by gamma-rays.

PubMed

Lee, S H; Jo, S H; Lee, S M; Koh, H J; Song, H; Park, J W; Lee, W H; Huh, T L

2004-09-01

To investigate the regulation of NADPH-producing isocitrate dehydrogenase (ICDH) in cytosol (IDPc) and mitochondria (IDPm) upon gamma-ray irradiation, and the roles of IDPc and IDPm in the protection against cellular damage induced by gamma-ray irradiation. Changes of IDPc and IDPm proteins upon gamma-ray irradiation to NIH3T3 cells were analysed by immunoblotting. To increase or decrease the expression of IDPc or IDPm, NIH3T3 cells were stably transfected with mouse IDPc or IDPm cDNA in either the sense or the antisense direction. The transfected cells with either increased or decreased IDPc or IDPm were exposed to gamma-rays, and the levels of reactive oxygen species generation, protein oxidation and lipid peroxidation were measured. Both IDPc and IDPm activities were induced by gamma-ray in NIH3T3 cells. Cells with decreased expression of IDPc or IDPm had elevated reactive oxygen species generation, lipid peroxidation and protein oxidation. Conversely, overproduction of IDPc or IDPm protein partially protected the cells from oxidative damage induced by gamma-ray irradiation. The protective role of IDPc and IDPm against gamma-ray-induced cellular damage can be attributed to elevated NADPH, reducing equivalents needed for recycling reduced glutathione in the cytosol and mitochondria. Thus, a primary biological function of the ICDHs may be production of NADPH, which is a prerequisite for some cellular defence systems against oxidative damage.

ATM Is Required for the Prolactin-Induced HSP90-Mediated Increase in Cellular Viability and Clonogenic Growth After DNA Damage.

PubMed

Karayazi Atici, Ödül; Urbanska, Anna; Gopinathan, Sesha Gopal; Boutillon, Florence; Goffin, Vincent; Shemanko, Carrie S

2018-02-01

Prolactin (PRL) acts as a survival factor for breast cancer cells, but the PRL signaling pathway and the mechanism are unknown. Previously, we identified the master chaperone, heat shock protein 90 (HSP90) α, as a prolactin-Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) target gene involved in survival, and here we investigated the role of HSP90 in the mechanism of PRL-induced viability in response to DNA damage. The ataxia-telangiectasia mutated kinase (ATM) protein plays a critical role in the cellular response to double-strand DNA damage. We observed that PRL increased viability of breast cancer cells treated with doxorubicin or etoposide. The increase in cellular resistance is specific to the PRL receptor, because the PRL receptor antagonist, Δ1-9-G129R-hPRL, prevented the increase in viability. Two different HSP90 inhibitors, 17-allylamino-17-demethoxygeldanamycin and BIIB021, reduced the PRL-mediated increase in cell viability of doxorubicin-treated cells and led to a decrease in JAK2, ATM, and phosphorylated ATM protein levels. Inhibitors of JAK2 (G6) and ATM (KU55933) abolished the PRL-mediated increase in cell viability of DNA-damaged cells, supporting the involvement of each, as well as the crosstalk of ATM with the PRL pathway in the context of DNA damage. Drug synergism was detected between the ATM inhibitor (KU55933) and doxorubicin and between the HSP90 inhibitor (BIIB021) and doxorubicin. Short interfering RNA directed against ATM prevented the PRL-mediated increase in cell survival in two-dimensional cell culture, three-dimensional collagen gel cultures, and clonogenic cell survival, after doxorubicin treatment. Our results indicate that ATM contributes to the PRL-JAK2-STAT5-HSP90 pathway in mediating cellular resistance to DNA-damaging agents. Copyright © 2018 Endocrine Society.

Bioenergetic metabolites regulate base excision repair dependent cell death in response to DNA damage

PubMed Central

Tang, Jiang-bo; Goellner, Eva M.; Wang, Xiao-hong; Trivedi, Ram N.; Croix, Claudette M. St; Jelezcova, Elena; Svilar, David; Brown, Ashley R.; Sobol, Robert W.

2009-01-01

Base excision repair (BER) protein expression is important for resistance to DNA damage-induced cytotoxicity. Conversely, BER imbalance (Polß deficiency or repair inhibition) enhances cytotoxicity of radiation and chemotherapeutic DNA-damaging agents. Whereas inhibition of critical steps in the BER pathway result in the accumulation of cytotoxic DNA double-strand breaks, we report that DNA damage-induced cytotoxicity due to deficiency in the BER protein Polß triggers cell death dependent on PARP activation yet independent of poly(ADP-ribose) (PAR)-mediated AIF nuclear translocation or PARG, suggesting that cytotoxicity is not from PAR or PAR-catabolite signaling. Cell death is rescued by the NAD+ metabolite NMN and is synergistic with inhibition of NAD+ biosynthesis, demonstrating that DNA damage-induced cytotoxicity mediated via BER inhibition is primarily dependent on cellular metabolite bioavailability. We offer a mechanistic justification for the elevated alkylation-induced cytotoxicity of Polß deficient cells, suggesting a linkage between DNA repair, cell survival and cellular bioenergetics. PMID:20068071

Role of Airway Recruitment and Derecruitment in Lung Injury

PubMed Central

Ghadiali, S. N.; Huang, Y.

2011-01-01

The mechanical forces generated during the ventilation of patients with acute lung injury causes significant lung damage and inflammation. Low-volume ventilation protocols are commonly used to prevent stretch-related injury that occurs at high lung volumes. However, the cyclic closure and reopening of pulmonary airways at low lung volumes, i.e., derecruitment and recruitment, also causes significant lung damage and inflammation. In this review, we provide an overview of how biomedical engineering techniques are being used to elucidate the complex physiological and biomechanical mechanisms responsible for cellular injury during recruitment/derecruitment. We focus on the development of multiscale, multiphysics computational models of cell deformation and injury during airway reopening. These models, and the corresponding in vitro experiments, have been used to both elucidate the basic mechanisms responsible for recruitment/derecruitment injury and to develop alternative therapies that make the epithelium more resistant to injury. For example, models and experiments indicate that fluidization of the cytoskeleton is cytoprotective and that changes in cytoskeletal structure and cell mechanics can be used to mitigate the mechanotransduction of oscillatory pressure into inflammatory signaling. The continued application of biomedical engineering techniques to the problem of recruitment/derecruitment injury may therefore lead to novel and more effective therapies. PMID:22011235

The association between expression of IFIT1 in podocytes of MRL/lpr mice and the renal pathological changes it causes: An animal study.

PubMed

Hu, Weiping; Niu, Guodong; Li, Hongbo; Gao, Hanyuan; Kang, Rudian; Chen, Xiaoqing; Lin, Ling

2016-11-22

Renal damage is the major cause of SLE associated mortality, and IFIT1expression was elevated in SLE cases in accordance of previous studies. Therefore, we conducted an animal study to identify the role of IFIT1 expression in renal pathological changes.18 female MRL/lpr mice and same number of female BALB/c mice were enrolled in present study. Quantitative analysis of urine protein, Complement C3 and C4, and anti-ds DNA antibody were conducted. HE and PAS staining and TEM analysis were employed to observe the pathological changes in renal tissue. Significant elevation on urine protein and anti-dsDNA and reduction on Complement C3 and C4 were observed in MRL/lpr mice when comparing the controls in same age. Staining and TEM analysis observed several pathological changes in glomerulus among MRL/lpr mice, including cellular enlargement, basement membrane thickening, and increased cellularcasts. The linear regression analysis found the optical density of IFIT1 was inversely associated with F-actin, Nephrin, and Podocin, but not Synatopodin. In summary, IFIT1 expression is associated with podocytes damage, and capable of suppressing some proteins essential to glomerular filtration.

Activation of Autophagy by Metals in Chlamydomonas reinhardtii.

PubMed

Pérez-Martín, Marta; Blaby-Haas, Crysten E; Pérez-Pérez, María Esther; Andrés-Garrido, Ascensión; Blaby, Ian K; Merchant, Sabeeha S; Crespo, José L

2015-09-01

Autophagy is an intracellular self-degradation pathway by which eukaryotic cells recycle their own material in response to specific stress conditions. Exposure to high concentrations of metals causes cell damage, although the effect of metal stress on autophagy has not been explored in photosynthetic organisms. In this study, we investigated the effect of metal excess on autophagy in the model unicellular green alga Chlamydomonas reinhardtii. We show in cells treated with nickel an upregulation of ATG8 that is independent of CRR1, a global regulator of copper signaling in Chlamydomonas. A similar effect on ATG8 was observed with copper and cobalt but not with cadmium or mercury ions. Transcriptome sequencing data revealed an increase in the abundance of the protein degradation machinery, including that responsible for autophagy, and a substantial overlap of that increased abundance with the hydrogen peroxide response in cells treated with nickel ions. Thus, our results indicate that metal stress triggers autophagy in Chlamydomonas and suggest that excess nickel may cause oxidative damage, which in turn activates degradative pathways, including autophagy, to clear impaired components and recover cellular homeostasis. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Proteasome inhibition induces DNA damage and reorganizes nuclear architecture and protein synthesis machinery in sensory ganglion neurons.

PubMed

Palanca, Ana; Casafont, Iñigo; Berciano, María T; Lafarga, Miguel

2014-05-01

Bortezomib is a reversible proteasome inhibitor used as an anticancer drug. However, its clinical use is limited since it causes peripheral neurotoxicity. We have used Sprague-Dawley rats as an animal model to investigate the cellular mechanisms affected by both short-term and chronic bortezomib treatments in sensory ganglia neurons. Proteasome inhibition induces dose-dependent alterations in the architecture, positioning, shape and polarity of the neuronal nucleus. It also produces DNA damage without affecting neuronal survival, and severe disruption of the protein synthesis machinery at the central cytoplasm accompanied by decreased expression of the brain-derived neurotrophic factor. As a compensatory or adaptive survival response against proteotoxic stress caused by bortezomib treatment, sensory neurons preserve basal levels of transcriptional activity, up-regulate the expression of proteasome subunit genes, and generate a new cytoplasmic perinuclear domain for protein synthesis. We propose that proteasome activity is crucial for controlling nuclear architecture, DNA repair and the organization of the protein synthesis machinery in sensory neurons. These neurons are primary targets of bortezomib neurotoxicity, for which reason their dysfunction may contribute to the pathogenesis of the bortezomib-induced peripheral neuropathy in treated patients.

Acute organo-phosphorus pesticide poisoning in North Karnataka, India: oxidative damage, haemoglobin level and total leukocyte.

PubMed

Hundekari, I A; Suryakar, A N; Rathi, D B

2013-03-01

Pesticide poisoning is an important cause of morbidity and mortality in India. To assess the oxidative damage, hemoglobin level and leukocyte count in acute organophosphorus pesticide poisoning. Plasma cholinesterase was assessed as a toxicity marker. Oxidative damage was assessed by estimating serum malondialdehyde (MDA) levels, plasma total antioxidant capacity (TAC), erythrocyte superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) levels. Progressive and significant decline (p< 0.001) in plasma cholinesterase in correlation with the severity of organophosphorus poisoning was observed. Serum MDA levels significantly increased (p< 0.001) in all grades of organophosphorus poisoning cases as compared to controls. Erythrocyte SOD, CAT and GPx were significantly increased (p< 0.05) in earlier grade and (p< 0.001) in later grades of organophosphorus poisoning cases as compared to controls. While plasma TAC (p<0.001) was significantly decreased in all grades of organophosphorus poisoning cases as compared to controls. Leucocytosis observed in these cases signifies the activation of defense mechanism which could be a positive response for survival. Organophosphorus compounds inhibit cholinesterase action leading to cholinergic hyperactivity. Increased MDA level may lead to peroxidative damages deteriorating the structural and functional integrity of neuronal membrane. Increased erythrocyte SOD, CAT and GPx activities suggest an adaptive measure to tackle the pesticide accumulation. Hence it is concluded that cholinesterase inhibition may initiate cellular dysfunction leading to acetylcholine induced oxidative damage.

Replicative stress and alterations in cell cycle checkpoint controls following acetaminophen hepatotoxicity restrict liver regeneration.

PubMed

Viswanathan, Preeti; Sharma, Yogeshwar; Gupta, Priya; Gupta, Sanjeev

2018-03-05

Acetaminophen hepatotoxicity is a leading cause of hepatic failure with impairments in liver regeneration producing significant mortality. Multiple intracellular events, including oxidative stress, mitochondrial damage, inflammation, etc., signify acetaminophen toxicity, although how these may alter cell cycle controls has been unknown and was studied for its significance in liver regeneration. Assays were performed in HuH-7 human hepatocellular carcinoma cells, primary human hepatocytes and tissue samples from people with acetaminophen-induced acute liver failure. Cellular oxidative stress, DNA damage and cell proliferation events were investigated by mitochondrial membrane potential assays, flow cytometry, fluorescence staining, comet assays and spotted arrays for protein expression after acetaminophen exposures. In experimental groups with acetaminophen toxicity, impaired mitochondrial viability and substantial DNA damage were observed with rapid loss of cells in S and G2/M and cell cycle restrictions or even exit in the remainder. This resulted from altered expression of the DNA damage regulator, ATM and downstream transducers, which imposed G1/S checkpoint arrest, delayed entry into S and restricted G2 transit. Tissues from people with acute liver failure confirmed hepatic DNA damage and cell cycle-related lesions, including restrictions of hepatocytes in aneuploid states. Remarkably, treatment of cells with a cytoprotective cytokine reversed acetaminophen-induced restrictions to restore cycling. Cell cycle lesions following mitochondrial and DNA damage led to failure of hepatic regeneration in acetaminophen toxicity but their reversibility offers molecular targets for treating acute liver failure. © 2018 John Wiley & Sons Ltd.

2, 3, 7, 8-Tetrachlorodibenzo-P-dioxin (TCDD) induces premature senescence in human and rodent neuronal cells via ROS-dependent mechanisms.

PubMed

Wan, Chunhua; Liu, Jiao; Nie, Xiaoke; Zhao, Jianya; Zhou, Songlin; Duan, Zhiqing; Tang, Cuiying; Liang, Lingwei; Xu, Guangfei

2014-01-01

The widespread environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a potent toxicant that causes significant neurotoxicity. However, the biological events that participate in this process remain largely elusive. In the present study, we demonstrated that TCDD exposure triggered apparent premature senescence in rat pheochromocytoma (PC12) and human neuroblastoma SH-SY5Y cells. Senescence-associated β-galactosidase (SA-β-Gal) assay revealed that TCDD induced senescence in PC12 neuronal cells at doses as low as 10 nM. TCDD led to F-actin reorganization and the appearance of an alternative senescence marker, γ-H2AX foci, both of which are important features of cellular senescence. In addition, TCDD exposure altered the expression of senescence marker proteins, such as p16, p21 and p-Rb, in both dose- and time-dependent manners. Furthermore, we demonstrated that TCDD promotes mitochondrial dysfunction and the accumulation of cellular reactive oxygen species (ROS) in PC12 cells, leading to the activation of signaling pathways that are involved in ROS metabolism and senescence. TCDD-induced ROS generation promoted significant oxidative DNA damage and lipid peroxidation. Notably, treatment with the ROS scavenger N-acetylcysteine (NAC) markedly attenuated TCDD-induced ROS production, cellular oxidative damage and neuronal senescence. Moreover, we found that TCDD induced a similar ROS-mediated senescence response in human neuroblastoma SH-SY5Y cells. In sum, these results demonstrate for the first time that TCDD induces premature senescence in neuronal cells by promoting intracellular ROS production, supporting the idea that accelerating the onset of neuronal senescence may be an important mechanism underlying TCDD-induced neurotoxic effects.

DMPS reverts morphologic and mitochondrial damage in OK cells exposed to toxic concentrations of HgCl2.

PubMed

Carranza-Rosales, Pilar; Guzmán-Delgado, Nancy E; Cruz-Vega, Delia E; Balderas-Rentería, Isaías; Gandolfi, A Jay

2007-05-01

Mercuric chloride (HgCl(2)) is a highly toxic compound, which can cause nephrotoxic damage. In the present study effects of HgCl(2) on mitochondria integrity and energy metabolism, as well as antidotal effects of 2,3-dimercaptopropane-1-sulfonate (DMPS) were investigated in the opossum kidney derived cell line (OK). OK cell monolayers were incubated during 0, 1, 3, 6, and 9 h in serum-free culture medium containing 15 microM HgCl(2), either in the absence or in the presence of 60 microM DMPS in a 1:4 ratio. Intracellular ATP content, MTT reduction, and HSP70/HSP90 induction were studied; confocal, transmission electron microscopy, and light microscopy studies were also performed. For confocal analysis, a mitochondrial selective probe (MitoTracker Red CMXH2Ros) was used. Antioxidant activity of DMPS was also studied by the scavenging of the free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) technique. A decrease of ATP content, an impaired ability to reduce tetrazolium, and dramatic changes on cellular and mitochondrial morphology, and energetic levels were found after either 6 or 9 h of HgCl(2) exposure. Increased expression of HSP90 and HSP70 were also seen. When OK cells were co-incubated with HgCl(2) and DMPS, cellular morphology, viability, intracellular ATP, and mitochondrial membrane potential were partially restored; a protective effect on mitochondrial morphology was also seen. DMPS also showed potent antioxidant activity in vitro. Mitochondrial protection could be the cellular mechanism mediated by DMPS in OK cells exposed to a toxic concentration of HgCl(2).

Increased resistance to acetaminophen hepatotoxicity in mice lacking glutathione S-transferase Pi

PubMed Central

Henderson, Colin J.; Wolf, C. Roland; Kitteringham, Neil; Powell, Helen; Otto, Diana; Park, B. Kevin

2000-01-01

Overdose of acetaminophen, a widely used analgesic drug, can result in severe hepatotoxicity and is often fatal. This toxic reaction is associated with metabolic activation by the P450 system to form a quinoneimine metabolite, N-acetyl-p-benzoquinoneimine (NAPQI), which covalently binds to proteins and other macromolecules to cause cellular damage. At low doses, NAPQI is efficiently detoxified, principally by conjugation with glutathione, a reaction catalyzed in part by the glutathione S-transferases (GST), such as GST Pi. To assess the role of GST in acetaminophen hepatotoxicity, we examined acetaminophen metabolism and liver damage in mice nulled for GstP (GstP1/P2(−/−)). Contrary to our expectations, instead of being more sensitive, GstP null mice were highly resistant to the hepatotoxic effects of this compound. No significant differences between wild-type (GstP1/P2(+/+)) mice and GstP1/P2(−/−) nulls in either the rate or route of metabolism, particularly to glutathione conjugates, or in the levels of covalent binding of acetaminophen-reactive metabolites to cellular protein were observed. However, although a similar rapid depletion of hepatic reduced glutathione (GSH) was found in both GstP1/P2(+/+) and GstP1/P2(−/−) mice, GSH levels only recovered in the GstP1/P2(−/−) mice. These data demonstrate that GstP does not contribute in vivo to the formation of glutathione conjugates of acetaminophen but plays a novel and unexpected role in the toxicity of this compound. This study identifies new ways in which GST can modulate cellular sensitivity to toxic effects and suggests that the level of GST Pi may be an important and contributing factor in the sensitivity of patients with acetaminophen-induced hepatotoxicity. PMID:11058152

The effects of fluoride on neuronal function occurs via cytoskeleton damage and decreased signal transmission.

PubMed

Chen, Lingli; Ning, Hongmei; Yin, Zhihong; Song, Xiaochao; Feng, Yongchao; Qin, Hao; Li, Yi; Wang, Jundong; Ge, Yaming; Wang, Wenkui

2017-10-01

It has been reported that fluoride exposure may cause serious public health problems, particularly neurotoxicity. However, the underlying mechanisms remain unclear. This study used Neuro-2A cells to investigate the effects of fluoride on the cytoskeleton. The Neuro-2A cells were exposed to 0, 1, 2, 4 and 6 mM sodium fluoride (NaF) for 24 h. Cell viability and lactate dehydrogenase (LDH) release were examined. It was observed that exposure to NaF reduced cell viability, disrupted cellular membrane integrity, and high levels of LDH were released. The observed changes occurred in a dose response manner. Morphologic observations showed that cell became rounded and were loosely adherent following exposure to NaF. Axon spines and normal features disappeared with high dose NaF treatment. The expression of MAP2 and synaptophysin decreased, particularly at 4 mM and 6 mM (P < 0.05) for MAP2. These results corroborate the morphologic observations. The content of glutamate and NMDAR (glutamate receptor) protein were assessed to help understand the relationship between synapses and neurotransmitter release using ELISA and Western-blot. Compared with the control, glutamate and NMDAR expression declined significantly at 4 mM and 6 mM (P < 0.05) group. Finally, the ultrastructural changes observed with increasing doses of NaF were: disappearance of synapses, mitochondrial agglutination, vacuole formation, and cellular edema. Taken together, NaF exposure disrupted cellular integrity and suppressed the release of neurotransmitters, thus effecting neuronal function. These findings provide deeper insights into roles of NaF in neuron damage, which could contribute to a better understanding of fluoride-induced neurotoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Involvement of DNA polymerase beta in repairing oxidative damages induced by antitumor drug adriamycin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Shukun; Wu Mei; Zhang Zunzhen, E-mail: zhangzunzhen@163.co

2010-08-01

Adriamycin (ADM) is a widely used antineoplastic drug. However, the increasing cellular resistance has become a serious limitation to ADM clinical application. The most important mechanism related to ADM-induced cell death is oxidative DNA damage mediated by reactive oxygen species (ROS). Base excision repair (BER) is a major pathway in the repair of DNA single strand break (SSB) and oxidized base. In this study, we firstly applied the murine embryo fibroblasts wild-type (pol {beta} +/+) and homozygous pol {beta} null cell (pol {beta} -/-) as a model to investigate ADM DNA-damaging effects and the molecular basis underlying these effects. Here,more » cellular sensitivity to ADM was examined using colorimetric assay and colony forming assay. ADM-induced cellular ROS level and the alteration of superoxide dismutase (SOD) activity were measured by commercial kits. Further, DNA strand break, chromosomal damage and gene mutation were assessed by comet assay, micronucleus test and hprt gene mutation assay, respectively. The results showed that pol {beta} -/- cells were more sensitive to ADM compared with pol {beta} +/+ cells and more severe SSB and chromosomal damage as well as higher hprt gene mutation frequency were observed in pol {beta} -/- cells. ROS level in pol {beta} -/- cells increased along with decreased activity of SOD. These results demonstrated that pol {beta} deficiency could enable ROS accumulation with SOD activity decrease, further elevate oxidative DNA damage, and subsequently result in SSB, chromosome cleavage as well as gene mutation, which may be partly responsible for the cytotoxicity of ADM and the hypersensitivity of pol {beta} -/- cells to ADM. These findings suggested that pol {beta} is vital for repairing oxidative damage induced by ADM.« less

Dunnione ameliorates cisplatin-induced small intestinal damage by modulating NAD{sup +} metabolism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandit, Arpana; Kim, Hyung-Jin; Oh, Gi-Su

2015-11-27

Although cisplatin is a widely used anticancer drug for the treatment of a variety of tumors, its use is critically limited because of adverse effects such as ototoxicity, nephrotoxicity, neuropathy, and gastrointestinal damage. Cisplatin treatment increases oxidative stress biomarkers in the small intestine, which may induce apoptosis of epithelial cells and thereby elicit damage to the small intestine. Nicotinamide adenine dinucleotide (NAD{sup +}) is a cofactor for various enzymes associated with cellular homeostasis. In the present study, we demonstrated that the hyper-activation of poly(ADP-ribose) polymerase-1 (PARP-1) is closely associated with the depletion of NAD{sup +} in the small intestine aftermore » cisplatin treatment, which results in downregulation of sirtuin1 (SIRT1) activity. Furthermore, a decrease in SIRT1 activity was found to play an important role in cisplatin-mediated small intestinal damage through nuclear factor (NF)-κB p65 activation, facilitated by its acetylation increase. However, use of dunnione as a strong substrate for the NADH:quinone oxidoreductase 1 (NQO1) enzyme led to an increase in intracellular NAD{sup +} levels and prevented the cisplatin-induced small intestinal damage correlating with the modulation of PARP-1, SIRT1, and NF-κB. These results suggest that direct modulation of cellular NAD{sup +} levels by pharmacological NQO1 substrates could be a promising therapeutic approach for protecting against cisplatin-induced small intestinal damage. - Highlights: • NAD{sup +} acts as a cofactor for numerous enzymes including Sirtuins and PARP. • Up-regulation of SIRT1 could attenuate the cisplatin-induced intestinal damage. • Modulation of the cellular NAD{sup +} could be a promising therapeutic approach.« less

Effects of Atmospheric Pressure Plasmas on Isolated and Cellular DNA—A Review

PubMed Central

Arjunan, Krishna Priya; Sharma, Virender K.; Ptasinska, Sylwia

2015-01-01

Atmospheric Pressure Plasma (APP) is being used widely in a variety of biomedical applications. Extensive research in the field of plasma medicine has shown the induction of DNA damage by APP in a dose-dependent manner in both prokaryotic and eukaryotic systems. Recent evidence suggests that APP-induced DNA damage shows potential benefits in many applications, such as sterilization and cancer therapy. However, in several other applications, such as wound healing and dentistry, DNA damage can be detrimental. This review reports on the extensive investigations devoted to APP interactions with DNA, with an emphasis on the critical role of reactive species in plasma-induced damage to DNA. The review consists of three main sections dedicated to fundamental knowledge of the interactions of reactive oxygen species (ROS)/reactive nitrogen species (RNS) with DNA and its components, as well as the effects of APP on isolated and cellular DNA in prokaryotes and eukaryotes. PMID:25642755

Lengthening our perspective: morphological, cellular, and molecular responses to eccentric exercise.

PubMed

Hyldahl, Robert D; Hubal, Monica J

2014-02-01

The response of skeletal muscle to unaccustomed eccentric exercise has been studied widely, yet it is incompletely understood. This review is intended to provide an up-to-date overview of our understanding of how skeletal muscle responds to eccentric actions, with particular emphasis on the underlying molecular and cellular mechanisms of damage and recovery. This review begins by addressing the question of whether eccentric actions result in physical damage to muscle fibers and/or connective tissue. We next review the symptomatic manifestations of eccentric exercise (i.e., indirect damage markers, such as delayed onset muscle soreness), with emphasis on their relatively poorly understood molecular underpinnings. We then highlight factors that potentially modify the muscle damage response following eccentric exercise. Finally, we explore the utility of using eccentric training to improve muscle function in populations of healthy and aging individuals, as well as those living with neuromuscular disorders. Copyright © 2013 Wiley Periodicals, Inc.

Effects of atmospheric pressure plasmas on isolated and cellular DNA-a review.

PubMed

Arjunan, Krishna Priya; Sharma, Virender K; Ptasinska, Sylwia

2015-01-29

Atmospheric Pressure Plasma (APP) is being used widely in a variety of biomedical applications. Extensive research in the field of plasma medicine has shown the induction of DNA damage by APP in a dose-dependent manner in both prokaryotic and eukaryotic systems. Recent evidence suggests that APP-induced DNA damage shows potential benefits in many applications, such as sterilization and cancer therapy. However, in several other applications, such as wound healing and dentistry, DNA damage can be detrimental. This review reports on the extensive investigations devoted to APP interactions with DNA, with an emphasis on the critical role of reactive species in plasma-induced damage to DNA. The review consists of three main sections dedicated to fundamental knowledge of the interactions of reactive oxygen species (ROS)/reactive nitrogen species (RNS) with DNA and its components, as well as the effects of APP on isolated and cellular DNA in prokaryotes and eukaryotes.

[Pain and emotional dysregulation: Cellular memory due to pain].

PubMed

Narita, Minoru; Watanabe, Moe; Hamada, Yusuke; Tamura, Hideki; Ikegami, Daigo; Kuzumaki, Naoko; Igarashi, Katsuhide

2015-08-01

Genetic factors are involved in determinants for the risk of psychiatric disorders, and neurological and neurodegenerative diseases. Chronic pain stimuli and intense pain have effects at a cellular and/or gene expression level, and will eventually induce "cellular memory due to pain", which means that tissue damage, even if only transient, can elicit epigenetically abnormal transcription/translation and post-translational modification in related cells depending on the degree or kind of injury or associated conditions. Such cell memory/transformation due to pain can cause an abnormality in a fundamental intracellular response, such as a change in the three-dimensional structure of DNA, transcription, or translation. On the other hand, pain is a multidimensional experience with sensory-discriminative and motivational-affective components. Recent human brain imaging studies have examined differences in activity in the nucleus accumbens between controls and patients with chronic pain, and have revealed that the nucleus accumbens plays a role in predicting the value of a noxious stimulus and its offset, and in the consequent changes in the motivational state. In this review, we provide a very brief overview of a comprehensive understanding of chronic pain associated with emotional dysregulation due to transcriptional regulation, epigenetic modification and miRNA regulation.

Secretory carrier membrane protein 5 is an autophagy inhibitor that promotes the secretion of α-synuclein via exosome.

PubMed

Yang, Yi; Qin, Meiling; Bao, Puhua; Xu, Wangchao; Xu, Jin

2017-01-01

Autophagy-lysosomal pathway is a cellular protective system to remove aggregated proteins and damaged organelles. Meanwhile, exosome secretion has emerged as a mode to selectively clear the neurotoxic proteins, such as α-synuclein. Mounting evidence suggests that these two cellular processes are coordinated to facilitate the clearance of toxic cellular waste; however the regulators for the transition between these two processes are unclear. Here we show that SCAMP5, a secretory carrier membrane protein significantly induced in the brains of Huntington's disease patients, is quickly and transiently induced by protein stress and autophagic stimulation, and is regulated by the master autophagy transcriptional regulator TFEB. Ironically, SCAMP5 inhibits autophagy flux by blocking the fusion of autophagosomes and lysosomes. Although autophagy is blocked, SCAMP5 does not cause significant protein aggregation in cells. Instead, it promotes the Golgi fragmentation and stimulates the unconventional secretion of the co-localizing α-synuclein via exosome as an exosome component. Therefore, we have identified SCAMP5 as a novel coordinator of autophagy and exosome secretion, which is induced upon protein stress to channel the efficient clearance of toxic proteins via the exosomes rather than autophagy-lysosomal pathway.

Regulation of autophagy by mTOR-dependent and mTOR-independent pathways: autophagy dysfunction in neurodegenerative diseases and therapeutic application of autophagy enhancers.

PubMed

Sarkar, Sovan

2013-10-01

Autophagy is an intracellular degradation pathway essential for cellular and energy homoeostasis. It functions in the clearance of misfolded proteins and damaged organelles, as well as recycling of cytosolic components during starvation to compensate for nutrient deprivation. This process is regulated by mTOR (mammalian target of rapamycin)-dependent and mTOR-independent pathways that are amenable to chemical perturbations. Several small molecules modulating autophagy have been identified that have potential therapeutic application in diverse human diseases, including neurodegeneration. Neurodegeneration-associated aggregation-prone proteins are predominantly degraded by autophagy and therefore stimulating this process with chemical inducers is beneficial in a wide range of transgenic disease models. Emerging evidence indicates that compromised autophagy contributes to the aetiology of various neurodegenerative diseases related to protein conformational disorders by causing the accumulation of mutant proteins and cellular toxicity. Combining the knowledge of autophagy dysfunction and the mechanism of drug action may thus be rational for designing targeted therapy. The present review describes the cellular signalling pathways regulating mammalian autophagy and highlights the potential therapeutic application of autophagy inducers in neurodegenerative disorders.

Role of Mitochondrial Oxidative Stress in Spaceflight-Induced Tissue Degeneration

NASA Technical Reports Server (NTRS)

Torres, Samantha M.; Schreurs, Ann-Sofie; Truong, Tiffany A.; Tahimic, Candice; Globus, Ruth

2017-01-01

Microgravity and ionizing radiation in the spaceflight environment poses multiple challenges to homeostasis and may contribute to cellular stress. Effects may include increased generation of reactive oxygen species (ROS), DNA damage and repair error, cell cycle arrest, cell senescence or death. Our central hypothesis is that prolonged exposure to the spaceflight environment leads to the excess production of ROS and oxidative damage, culminating in accelerated tissue degeneration. The main goal of this project is to determine the importance of cellular redox defense for physiological adaptations and tissue degeneration in the space environment.

Cooperative biological effects between ionizing radiation and other physical and chemical agents.

PubMed

Manti, Lorenzo; D'Arco, Annalisa

2010-01-01

Exposure to ionizing radiation (IR), at environmentally and therapeutically relevant doses or as a result of diagnostics or accidents, causes cyto- and genotoxic damage. However, exposure to IR alone is a rare event as it occurs in spatial and temporal combination with several physico-chemical agents. Some of these are of known noxiousness, as is the case with chemical compounds at high dose, hence additive/synergistic effects can be expected or have been demonstrated. Conversely, the cellular toxicity of other agents, such as non-ionizing electromagnetic fields (EMFs), is only presumed and their short- and long-term cooperation on IR-induced damage remains undetermined. In this review, we shall examine evidence in support of the interplay between spatially and/or temporally related environmentally relevant stressors. In vitro or animal-based studies as well as epidemiological surveys have generally examined the combined action of no more than a couple of known or potentially DNA-damaging agents. Moreover, most existing research mainly focused on short-term effects of combined exposures. Hence, it is important that quantitative research addresses the issue of the possible cooperation between chronic exposure to environmental trace contaminants and exposure to EMFs, examining not only the modulation of damage acutely induced by IR but also long-term genome stability. 2010 Elsevier B.V. All rights reserved.

Recovery from DNA damage-induced G2 arrest requires actin-binding protein filamin-A/actin-binding protein 280.

PubMed

Meng, Xiangbing; Yuan, Yuan; Maestas, Adrian; Shen, Zhiyuan

2004-02-13

Filamin-A (filamin-1) is an actin-binding protein involved in the organization of actin networks. Our previous study shows that filamin-A interacts with BRCA2, and lack of filamin-A expression results in increased cellular sensitivity to several DNA damaging agents in melanoma cells (Yuan, Y., and Shen, Z. (2001) J. Biol. Chem. 276, 48318-48324), suggesting a role of filamin-A in DNA damage response. In this report, we demonstrated that deficiency of filamin-A results in an 8-h delay in the recovery from G2 arrest in response to ionizing radiation. However, filamin-A deficiency does not affect the initial activation of the G2/M checkpoint. We also found that filamin-A deficiency results in sustained activation of Chk1 and Chk2 after irradiation. This in turn causes a delay in the dephosphorylation of phospho-Cdc2, which is inhibitory to the G2/M transition. In addition, filamin-A-deficient M2 cells undergo mitotic catastrophe-related nuclear fragmentation after they are released from the G2 arrest. Together, these data suggest a functional role of filamin-A in the recovery from G2 arrest and subsequent mitotic cell death after DNA damage.

Chemotherapeutic-Induced Cardiovascular Dysfunction: Physiological Effects, Early Detection—The Role of Telomerase to Counteract Mitochondrial Defects and Oxidative Stress

PubMed Central

Quryshi, Nabeel; Norwood Toro, Laura E.; Ait-Aissa, Karima; Kong, Amanda; Beyer, Andreas M.

2018-01-01

Although chemotherapeutics can be highly effective at targeting malignancies, their ability to trigger cardiovascular morbidity is clinically significant. Chemotherapy can adversely affect cardiovascular physiology, resulting in the development of cardiomyopathy, heart failure and microvascular defects. Specifically, anthracyclines are known to cause an excessive buildup of free radical species and mitochondrial DNA damage (mtDNA) that can lead to oxidative stress-induced cardiovascular apoptosis. Therefore, oncologists and cardiologists maintain a network of communication when dealing with patients during treatment in order to treat and prevent chemotherapy-induced cardiovascular damage; however, there is a need to discover more accurate biomarkers and therapeutics to combat and predict the onset of cardiovascular side effects. Telomerase, originally discovered to promote cellular proliferation, has recently emerged as a potential mechanism to counteract mitochondrial defects and restore healthy mitochondrial vascular phenotypes. This review details mechanisms currently used to assess cardiovascular damage, such as C-reactive protein (CRP) and troponin levels, while also unearthing recently researched biomarkers, including circulating mtDNA, telomere length and telomerase activity. Further, we explore a potential role of telomerase in the mitigation of mitochondrial reactive oxygen species and maintenance of mtDNA integrity. Telomerase activity presents a promising indicator for the early detection and treatment of chemotherapy-derived cardiac damage. PMID:29534446

Comet Assay: A Method to Evaluate Genotoxicity of Nano-Drug Delivery System

PubMed Central

Vandghanooni, Somayeh; Eskandani, Morteza

2011-01-01

Introduction Drug delivery systems could induce cellular toxicity as side effect of nanomaterials. The mechanism of toxicity usually involves DNA damage. The comet assay or single cell gel electrophoresis (SCGE) is a sensitive method for detecting strand damages in the DNA of a cell with applications in genotoxicity testing and molecular epidemiology as well as fundamental research in DNA damage and repair. Methods In the current study, we reviewed recent drug delivery researches related to SCGE. Results We found that one preference for choosing the assay is that comet images may result from apoptosis-mediated nuclear fragmentation. This method has been widely used over the last decade in several different areas. Overall cells, such as cultured cells are embedded in agarose on a microscope slide, lysed with detergent, and treated with high salt. Nucleoids are supercoiled DNA form. When the slide is faced to alkaline electrophoresis any breakages present in the DNA cause the supercoiling to relax locally and loops of DNA extend toward the anode as a ‘‘comet tail’’. Conclusion This article provides a relatively comprehensive review upon potentiality of the comet assay for assessment of DNA damage and accordingly it can be used as an informative platform in genotoxicity studies of drug delivery systems. PMID:23678412

Genomic instability in human cancer: Molecular insights and opportunities for therapeutic attack and prevention through diet and nutrition

PubMed Central

Ferguson, Lynnette R.; Chen, Helen; Collins, Andrew R.; Connell, Marisa; Damia, Giovanna; Dasgupta, Santanu; Malhotra, Meenakshi; Meeker, Alan K.; Amedei, Amedeo; Amin, Amr; Ashraf, S. Salman; Aquilano, Katia; Azmi, Asfar S.; Bhakta, Dipita; Bilsland, Alan; Boosani, Chandra S.; Chen, Sophie; Ciriolo, Maria Rosa; Fujii, Hiromasa; Guha, Gunjan; Halicka, Dorota; Helferich, William G.; Keith, W. Nicol; Mohammed, Sulma I.; Niccolai, Elena; Yang, Xujuan; Honoki, Kanya; Parslow, Virginia R.; Prakash, Satya; Rezazadeh, Sarallah; Shackelford, Rodney E.; Sidransky, David; Tran, Phuoc T.; Yang, Eddy S.; Maxwell, Christopher A.

2015-01-01

Genomic instability can initiate cancer, augment progression, and influence the overall prognosis of the affected patient. Genomic instability arises from many different pathways, such as telomere damage, centrosome amplification, epigenetic modifications, and DNA damage from endogenous and exogenous sources, and can be perpetuating, or limiting, through the induction of mutations or aneuploidy, both enabling and catastrophic. Many cancer treatments induce DNA damage to impair cell division on a global scale but it is accepted that personalized treatments, those that are tailored to the particular patient and type of cancer, must also be developed. In this review, we detail the mechanisms from which genomic instability arises and can lead to cancer, as well as treatments and measures that prevent genomic instability or take advantage of the cellular defects caused by genomic instability. In particular, we identify and discuss five priority targets against genomic instability: (1) prevention of DNA damage; (2) enhancement of DNA repair; (3) targeting deficient DNA repair; (4) impairing centrosome clustering; and, (5) inhibition of telomerase activity. Moreover, we highlight vitamin D and B, selenium, carotenoids, PARP inhibitors, resveratrol, and isothiocyanates as priority approaches against genomic instability. The prioritized target sites and approaches were cross validated to identify potential synergistic effects on a number of important areas of cancer biology. PMID:25869442

[Therapeutic effect of human mesenchymal stem cells in skin after radiation damage].

PubMed

Bensidhoum, Morad; Gobin, Stéphanie; Chapel, Alain; Lemaitre, Gilles; Bouet, Stéphan; Waksman, Gilles; Thierry, Dominique; Martin, Michèle T

2005-01-01

Over 50% of all cancer patients presently receive radiotherapy at one stage in their treatment course. Inevitably skin is one of the most frequently damaged tissue due to its localization and constant turn-over. Our present goal is to reduce radiation-induced complications in human skin through stem cell therapy, particulary in human epidermis. Mesenchymal Stem Cells (MSCs) have been shown to be multipotent cells able to engraft in many tissues after injury. Herein, we isolated human MSCs and tested their capability to improve skin wound healing after irradiation. This potential was assessed in NOD/SCID mice which received 30 Gy locally on the thigh. This dose caused within 3 weeks local epidermis necrosis which was repaired within 13 weeks. MSCs were intravenously injected in irradiated mice 24 hours after exposure. Clinical scoring throughout 6 weeks gave indications that human MSCs reduced the extent of damage and accelerated the wound healing process. We show by quantitative qPCR and histological studies the presence of human MSCs derived cells into the scar. Human MSCs homed to the damaged skin and participated to the wound healing process. These results open prospects for cellular therapy by MSCs in irradiated epithelial tissues and could be extended to the whole general field of cutaneous cicatrization, particularly after burns.

Dynamic contrast-enhanced optical imaging of in vivo organ function

NASA Astrophysics Data System (ADS)

Amoozegar, Cyrus B.; Wang, Tracy; Bouchard, Matthew B.; McCaslin, Addason F. H.; Blaner, William S.; Levenson, Richard M.; Hillman, Elizabeth M. C.

2012-09-01

Conventional approaches to optical small animal molecular imaging suffer from poor resolution, limited sensitivity, and unreliable quantitation, often reducing their utility in practice. We previously demonstrated that the in vivo dynamics of an injected contrast agent could be exploited to provide high-contrast anatomical registration, owing to the temporal differences in each organ's response to the circulating fluorophore. This study extends this approach to explore whether dynamic contrast-enhanced optical imaging (DyCE) can allow noninvasive, in vivo assessment of organ function by quantifying the differing cellular uptake or wash-out dynamics of an agent in healthy and damaged organs. Specifically, we used DyCE to visualize and measure the organ-specific uptake dynamics of indocyanine green before and after induction of transient liver damage. DyCE imaging was performed longitudinally over nine days, and blood samples collected at each imaging session were analyzed for alanine aminotransferase (ALT), a liver enzyme assessed clinically as a measure of liver damage. We show that changes in DyCE-derived dynamics of liver and kidney dye uptake caused by liver damage correlate linearly with ALT concentrations, with an r2 value of 0.91. Our results demonstrate that DyCE can provide quantitative, in vivo, longitudinal measures of organ function with inexpensive and simple data acquisition.

Bile-acid-induced cell injury and protection

PubMed Central

Perez, Maria J; Briz, Oscar

2009-01-01

Several studies have characterized the cellular and molecular mechanisms of hepatocyte injury caused by the retention of hydrophobic bile acids (BAs) in cholestatic diseases. BAs may disrupt cell membranes through their detergent action on lipid components and can promote the generation of reactive oxygen species that, in turn, oxidatively modify lipids, proteins, and nucleic acids, and eventually cause hepatocyte necrosis and apoptosis. Several pathways are involved in triggering hepatocyte apoptosis. Toxic BAs can activate hepatocyte death receptors directly and induce oxidative damage, thereby causing mitochondrial dysfunction, and induce endoplasmic reticulum stress. When these compounds are taken up and accumulate inside biliary cells, they can also cause apoptosis. Regarding extrahepatic tissues, the accumulation of BAs in the systemic circulation may contribute to endothelial injury in the kidney and lungs. In gastrointestinal cells, BAs may behave as cancer promoters through an indirect mechanism involving oxidative stress and DNA damage, as well as acting as selection agents for apoptosis-resistant cells. The accumulation of BAs may have also deleterious effects on placental and fetal cells. However, other BAs, such as ursodeoxycholic acid, have been shown to modulate BA-induced injury in hepatocytes. The major beneficial effects of treatment with ursodeoxycholic acid are protection against cytotoxicity due to more toxic BAs; the stimulation of hepatobiliary secretion; antioxidant activity, due in part to an enhancement in glutathione levels; and the inhibition of liver cell apoptosis. Other natural BAs or their derivatives, such as cholyl-N-methylglycine or cholylsarcosine, have also aroused pharmacological interest owing to their protective properties. PMID:19360911

Hepatitis B surface antigen (HBsAg) and core antigen (HBcAg) combine CpG oligodeoxynucletides as a novel therapeutic vaccine for chronic hepatitis B infection.

PubMed

Li, Jianqiang; Ge, Jun; Ren, Sulin; Zhou, Tong; Sun, Ying; Sun, Honglin; Gu, Yue; Huang, Hongying; Xu, Zhenxing; Chen, Xiaoxiao; Xu, Xiaowei; Zhuang, Xiaoqian; Song, Cuiling; Jia, Fangmiao; Xu, Aiguo; Yin, Xiaojin; Du, Sean X

2015-08-20

Hepatitis B virus infection is a non-cytopathic hepatotropic virus which can lead to chronic liver disease and hepatocellular carcinoma. Traditional therapies fail to provide sustained control of viral replication and liver damage in most patients. As an alternative strategy, immunotherapeutic approaches have shown promising efficacy in the treatment of chronic hepatitis B patients. Here, we investigated the efficacy of a novel therapeutic vaccine formulation consisting of two HBV antigens, HBsAg and HBcAg, and CpG adjuvant. This vaccine formulation elicits forceful humoral responses directed against HBsAg/HBcAg, and promotes a Th1/Th2 balance response against HBsAg and a Th1-biased response against HBcAg in both C57BL/6 and HBV transgenic mice. Vigorous cellular immune response was also detected in HBV transgenic mice, for a significantly higher number of HBs/HBc-specific IFN-γ secreting CD4+ and CD8+ T cells was generated. Moreover, vaccinated mice elicited significantly intense in vivo CTL attack, reduced serum HBsAg level without causing liver damage in HBV transgenic mice. In summary, this study demonstrates a novel therapeutic vaccine with the potential to elicit vigorous humoral and cellular response, overcoming tolerance in HBV transgenic mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physiology of a microgravity environment invited review: microgravity and skeletal muscle

NASA Technical Reports Server (NTRS)

Fitts, R. H.; Riley, D. R.; Widrick, J. J.

2000-01-01

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity of shortening in the type I and IIa fiber types. Importantly, the microgravity-induced decline in peak power is partially offset by the increased fiber velocity. Muscle velocity is further increased by the microgravity-induced expression of fast-type myosin isozymes in slow fibers (hybrid I/II fibers) and by the increased expression of fast type II fiber types. SF increases the susceptibility of skeletal muscle to damage, with the actual damage elicited during postflight reloading. Evidence in rats indicates that SF increases fatigability and reduces the capacity for fat oxidation in skeletal muscles. Future studies will be required to establish the cellular and molecular mechanisms of the SF-induced muscle atrophy and functional loss and to develop effective exercise countermeasures.

Staying young at heart: autophagy and adaptation to cardiac aging.

PubMed

Leon, Leonardo J; Gustafsson, Åsa B

2016-06-01

Aging is a predominant risk factor for developing cardiovascular disease. Therefore, the cellular processes that contribute to aging are attractive targets for therapeutic interventions that can delay or prevent the development of age-related diseases. Our understanding of the underlying mechanisms that contribute to the decline in cell and tissue functions with age has greatly advanced over the past decade. Classical hallmarks of aging cells include increased levels of reactive oxygen species, DNA damage, accumulation of dysfunctional organelles, oxidized proteins and lipids. These all contribute to a progressive decline in the normal physiological function of the cell and to the onset of age-related conditions. A major cause of the aging process is progressive loss of cellular quality control. Autophagy is an important quality control pathway and is necessary to maintain cardiac homeostasis and to adapt to stress. A reduction in autophagy has been observed in a number of aging models and there is compelling evidence that enhanced autophagy delays aging and extends life span. Enhancing autophagy counteracts age-associated accumulation of protein aggregates and damaged organelles in cells. In this review, we discuss the functional role of autophagy in maintaining homeostasis in the heart, and how a decline is associated with accelerated cardiac aging. We also evaluate therapeutic approaches being researched in an effort to maintain a healthy young heart. Copyright © 2015 Elsevier Ltd. All rights reserved.

Strawberry-Based Cosmetic Formulations Protect Human Dermal Fibroblasts against UVA-Induced Damage

PubMed Central

Gasparrini, Massimiliano; Forbes-Hernandez, Tamara Y.; Afrin, Sadia; Reboredo-Rodriguez, Patricia; Cianciosi, Danila; Mezzetti, Bruno; Quiles, Josè L.; Bompadre, Stefano; Battino, Maurizio; Giampieri, Francesca

2017-01-01

Extreme exposure of skin to Ultraviolet A (UVA)-radiation may induce a dysregulated production of reactive oxygen species (ROS) which can interact with cellular biomolecules leading to oxidative stress, inflammation, DNA damage, and alteration of cellular molecular pathways, responsible for skin photoaging, hyperplasia, erythema, and cancer. For these reasons, the use of dietary natural bioactive compounds with remarkable antioxidant activity could be a strategic tool to counteract these UVA-radiation-caused deleterious effects. Thus, the purpose of the present work was to test the efficacy of strawberry (50 μg/mL)-based formulations supplemented with Coenzyme Q10 (100 μg/mL) and sun protection factor 10 in human dermal fibroblasts irradiated with UVA-radiation. The apoptosis rate, the amount of intracellular reactive oxygen species (ROS) production, the expression of proteins involved in antioxidant and inflammatory response, and mitochondrial functionality were evaluated. The results showed that the synergic topical use of strawberry and Coenzyme Q10 provided a significant (p < 0.05) photoprotective effect, reducing cell death and ROS, increasing antioxidant defense, lowering inflammatory markers, and improving mitochondrial functionality. The obtained results suggest the use of strawberry-based formulations as an innovative, natural, and useful tool for the prevention of UVA exposure-induced skin diseases in order to decrease or substitute the amount of synthetic sunscreen agents. PMID:28613256

A Clinical, Biological, and Biomaterials Perspective into Tendon Injuries and Regeneration

PubMed Central

Walden, Grace; Liao, Xin; Donell, Simon; Raxworthy, Mike J.; Riley, Graham P.

2017-01-01

Tendon injury is common and debilitating, and it is associated with long-term pain and ineffective healing. It is estimated to afflict 25% of the adult population and is often a career-ending disease in athletes and racehorses. Tendon injury is associated with high morbidity, pain, and long-term suffering for the patient. Due to the low cellularity and vascularity of tendon tissue, once damage has occurred, the repair process is slow and inefficient, resulting in mechanically, structurally, and functionally inferior tissue. Current treatment options focus on pain management, often being palliative and temporary and ending in reduced function. Most treatments available do not address the underlying cause of the disease and, as such, are often ineffective with variable results. The need for an advanced therapeutic that addresses the underlying pathology is evident. Tissue engineering and regenerative medicine is an emerging field that is aimed at stimulating the body's own repair system to produce de novo tissue through the use of factors such as cells, proteins, and genes that are delivered by a biomaterial scaffold. Successful tissue engineering strategies for tendon regeneration should be built on a foundation of understanding of the molecular and cellular composition of healthy compared with damaged tendon, and the inherent differences seen in the tissue after disease. This article presents a comprehensive clinical, biological, and biomaterials insight into tendon tissue engineering and regeneration toward more advanced therapeutics. PMID:27596929

High-level iron mitigates fusaricidin-induced membrane damage and reduces membrane fluidity leading to enhanced drug resistance in Bacillus subtilis.

PubMed

Yu, Wen-Bang; Ye, Bang-Ce

2016-05-01

Fusaricidins are a class of cyclic lipopeptide antibiotics that have strong antifungal activities against plant pathogenic fungi and excellent bactericidal activities against Gram-positive bacteria. The mechanism through which fusaricidin exerts its action is not yet entirely clear. To investigate the mode of action of fusaricidin, we determined the physiological and transcriptional responses of Bacillus subtilis to fusaricidin treatment by using a systems-level approach. Our data show that fusaricidin rapidly induced the expression of σ(W) regulon and caused membrane damage in B. subtilis. We further demonstrated that ferric ions play multiple roles in the action of fusaricidin on B. subtilis. Iron deprivation blocked the formation of hydroxyl radical in the cells and significantly inhibited the bactericidal activity of fusaricidin. Conversely, high levels of iron (>2 mM) repressed the expression of BkdR regulon, resulting in a smaller cellular pool of branched-chain precursors for iso- and anteiso-branched fatty acids, which in turn led to a decrease in the proportion of branched-chain fatty acids in the membrane of B. subtilis. This change in membrane composition reduced its bilayer fluidity and increased its resistance to antimicrobial agents. In conclusion, our experiments uncovered some novel interactions and a synergism between cellular iron levels and drug resistance in Gram-positive bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cognitive Function of Artemisia argyi H. Fermented by Monascus purpureus under TMT-Induced Learning and Memory Deficits in ICR Mice

PubMed Central

Kang, Jin Yong; Lee, Du Sang; Park, Seon Kyeong; Ha, Jeong Su; Kim, Jong Min; Ha, Gi Jeong; Seo, Weon Taek

2017-01-01

The cognitive effect of Artemisia argyi H. under liquid-state fermentation by Monascus purpureus (AAFM), which has cellular antioxidant activity and neuronal cell viability, on trimethyltin- (TMT-) induced learning and memory impairment in Institute of Cancer Research (ICR) mice was confirmed. Tests were conducted to determine the neuroprotective effects against H2O2-induced oxidative stress, and the results showed that AAFM has protective effects through the repression of mitochondrial injury and cellular membrane damage against H2O2-induced neurotoxicity. In animal experiments, such as the Y-maze, passive avoidance, and Morris water maze tests, AAFM also showed excellent ameliorating effects on TMT-induced cognitive dysfunction. After behavioral tests, brain tissues were extracted to assess damage to brain tissue. According to the experimental results, AAFM improved the cholinergic system by upregulating acetylcholine (ACh) contents and inhibiting acetylcholinesterase (AChE) activity. AAFM effectively improved the decline of the superoxide dismutase (SOD) level and the increase of the oxidized glutathione (GSH) ratio and lipid peroxidation (malondialdehyde (MDA) production) caused by TMT-induced oxidative stress. The occurrence of mitochondrial dysfunction and apoptosis was also decreased compared with the TMT group. Finally, quinic acid derivatives were identified as the major phenolic compounds in AAFM using ultra-performance liquid chromatography quadrupole-time-of-flight (UPLC-Q-TOF) MS analysis. PMID:29081819

Cognitive Function of Artemisia argyi H. Fermented by Monascus purpureus under TMT-Induced Learning and Memory Deficits in ICR Mice.

PubMed

Kang, Jin Yong; Lee, Du Sang; Park, Seon Kyeong; Ha, Jeong Su; Kim, Jong Min; Ha, Gi Jeong; Seo, Weon Taek; Heo, Ho Jin

2017-01-01

The cognitive effect of Artemisia argyi H. under liquid-state fermentation by Monascus purpureus (AAFM), which has cellular antioxidant activity and neuronal cell viability, on trimethyltin- (TMT-) induced learning and memory impairment in Institute of Cancer Research (ICR) mice was confirmed. Tests were conducted to determine the neuroprotective effects against H 2 O 2 -induced oxidative stress, and the results showed that AAFM has protective effects through the repression of mitochondrial injury and cellular membrane damage against H 2 O 2 -induced neurotoxicity. In animal experiments, such as the Y-maze, passive avoidance, and Morris water maze tests, AAFM also showed excellent ameliorating effects on TMT-induced cognitive dysfunction. After behavioral tests, brain tissues were extracted to assess damage to brain tissue. According to the experimental results, AAFM improved the cholinergic system by upregulating acetylcholine (ACh) contents and inhibiting acetylcholinesterase (AChE) activity. AAFM effectively improved the decline of the superoxide dismutase (SOD) level and the increase of the oxidized glutathione (GSH) ratio and lipid peroxidation (malondialdehyde (MDA) production) caused by TMT-induced oxidative stress. The occurrence of mitochondrial dysfunction and apoptosis was also decreased compared with the TMT group. Finally, quinic acid derivatives were identified as the major phenolic compounds in AAFM using ultra-performance liquid chromatography quadrupole-time-of-flight (UPLC-Q-TOF) MS analysis.

Suppression of the E. coli SOS response by dNTP pool changes.

PubMed

Maslowska, Katarzyna H; Makiela-Dzbenska, Karolina; Fijalkowska, Iwona J; Schaaper, Roel M

2015-04-30

The Escherichia coli SOS system is a well-established model for the cellular response to DNA damage. Control of SOS depends largely on the RecA protein. When RecA is activated by single-stranded DNA in the presence of a nucleotide triphosphate cofactor, it mediates cleavage of the LexA repressor, leading to expression of the 30(+)-member SOS regulon. RecA activation generally requires the introduction of DNA damage. However, certain recA mutants, like recA730, bypass this requirement and display constitutive SOS expression as well as a spontaneous (SOS) mutator effect. Presently, we investigated the possible interaction between SOS and the cellular deoxynucleoside triphosphate (dNTP) pools. We found that dNTP pool changes caused by deficiencies in the ndk or dcd genes, encoding nucleoside diphosphate kinase and dCTP deaminase, respectively, had a strongly suppressive effect on constitutive SOS expression in recA730 strains. The suppression of the recA730 mutator effect was alleviated in a lexA-deficient background. Overall, the findings suggest a model in which the dNTP alterations in the ndk and dcd strains interfere with the activation of RecA, thereby preventing LexA cleavage and SOS induction. Published by Oxford University Press on behalf of Nucleic Acids Research 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Cell Therapy and Tissue Engineering Approaches for Cartilage Repair and/or Regeneration

PubMed Central

Mardones, Rodrigo; Jofré, Claudio M.; Minguell, José J.

2015-01-01

Articular cartilage injuries caused by traumatic, mechanical and/or by progressive degeneration result in pain, swelling, subsequent loss of joint function and finally osteoarthritis. Due to the peculiar structure of the tissue (no blood supply), chondrocytes, the unique cellular phenotype in cartilage, receive their nutrition through diffusion from the synovial fluid and this limits their intrinsic capacity for healing. The first cellular avenue explored for cartilage repair involved the in situ transplantation of isolated chondrocytes. Latterly, an improved alternative for the above reparative strategy involved the infusion of mesenchymal stem cells (MSC), which in addition to a self-renewal capacity exhibit a differentiation potential to chondrocytes, as well as a capability to produce a vast array of growth factors, cytokines and extracellular matrix compounds involved in cartilage development. In addition to the above and foremost reparative options up till now in use, other therapeutic options have been developed, comprising the design of biomaterial substrates (scaffolds) capable of sustaining MSC attachment, proliferation and differentiation. The implantation of these engineered platforms, closely to the site of cartilage damage, may well facilitate the initiation of an ‘in situ’ cartilage reparation process. In this mini-review, we examined the timely and conceptual development of several cell-based methods, designed to repair/regenerate a damaged cartilage. In addition to the above described cartilage reparative options, other therapeutic alternatives still in progress are portrayed. PMID:26019754

Cell Therapy and Tissue Engineering Approaches for Cartilage Repair and/or Regeneration.

PubMed

Mardones, Rodrigo; Jofré, Claudio M; Minguell, José J

2015-05-01

Articular cartilage injuries caused by traumatic, mechanical and/or by progressive degeneration result in pain, swelling, subsequent loss of joint function and finally osteoarthritis. Due to the peculiar structure of the tissue (no blood supply), chondrocytes, the unique cellular phenotype in cartilage, receive their nutrition through diffusion from the synovial fluid and this limits their intrinsic capacity for healing. The first cellular avenue explored for cartilage repair involved the in situ transplantation of isolated chondrocytes. Latterly, an improved alternative for the above reparative strategy involved the infusion of mesenchymal stem cells (MSC), which in addition to a self-renewal capacity exhibit a differentiation potential to chondrocytes, as well as a capability to produce a vast array of growth factors, cytokines and extracellular matrix compounds involved in cartilage development. In addition to the above and foremost reparative options up till now in use, other therapeutic options have been developed, comprising the design of biomaterial substrates (scaffolds) capable of sustaining MSC attachment, proliferation and differentiation. The implantation of these engineered platforms, closely to the site of cartilage damage, may well facilitate the initiation of an 'in situ' cartilage reparation process. In this mini-review, we examined the timely and conceptual development of several cell-based methods, designed to repair/regenerate a damaged cartilage. In addition to the above described cartilage reparative options, other therapeutic alternatives still in progress are portrayed.

The therapeutic effect of artesunate on rosacea through the inhibition of the JAK/STAT signaling pathway.

PubMed

Li, Ting; Zeng, Qingwen; Chen, Xingming; Wang, Guojiang; Zhang, Haiqing; Yu, Aihua; Wang, Hairui; Hu, Yang

2018-06-01

Acne rosacea is a type of chronic dermatosis with the characteristics of erubescence, angiotelectasis and pustule formation. However, current treatment methods are limited due to the side effects. Artesunate demonstrated a promising therapeutic efficacy with a high safety margin. HaCaT cells were treated with antibacterial peptide LL‑37 to simulate rosacea caused by Demodex folliculorum (D. folliculorum) infection. Cell Counting kit 8 and flow cytometry assays were performed to measure cellular proliferation, apoptosis, the stage of the cell cycle and reactive oxygen species generation in order to determine the level of cell damage. Then the damaged cells were treated with different concentrations of artesunate and doxycycline to determine the therapeutic effect of artesunate. Pro‑inflammatory cytokines tumor necrosis factor‑α (TNF‑α), interleukin (IL)‑6, IL‑8 and C‑C motif chemokine 2 (MCP‑1) were measured using an ELISA, while western blotting was used to detect the expression of Janus kinase 2 (JAK2) and signal transducer and transcription activator (STAT3). As a result, LL‑37 treated HaCaT cells decreased in cell viability, had an increased apoptotic rate and cell cycle arrest, indicating that cell damage caused by rosacea was simulated. In addition, upregulated concentrations of the pro‑inflammatory cytokines TNF‑α, IL‑6, IL‑8 and MCP‑1 were attenuated in the artesunate group in a dose‑dependent fashion, indicating the therapeutic effect of artesunate. Furthermore, higher concentrations of artesunate exhibited an improved effect compared with the doxycycline group. In addition, increased expression levels of JAK2 and STAT3 following treatment with LL‑37 suggested that rosacea caused by D. folliculorum infection may lead to inflammation through the JAK/STAT signaling pathway. In conclusion, the potential mechanism by which damage occurs in rosacea was revealed and a promising therapeutic method against rosacea was demonstrated.

Inactivating UBE2M impacts the DNA damage response and genome integrity involving multiple cullin ligases.

PubMed

Cukras, Scott; Morffy, Nicholas; Ohn, Takbum; Kee, Younghoon

2014-01-01

Protein neddylation is involved in a wide variety of cellular processes. Here we show that the DNA damage response is perturbed in cells inactivated with an E2 Nedd8 conjugating enzyme UBE2M, measured by RAD51 foci formation kinetics and cell based DNA repair assays. UBE2M knockdown increases DNA breakages and cellular sensitivity to DNA damaging agents, further suggesting heightened genomic instability and defective DNA repair activity. Investigating the downstream Cullin targets of UBE2M revealed that silencing of Cullin 1, 2, and 4 ligases incurred significant DNA damage. In particular, UBE2M knockdown, or defective neddylation of Cullin 2, leads to a blockade in the G1 to S progression and is associated with delayed S-phase dependent DNA damage response. Cullin 4 inactivation leads to an aberrantly high DNA damage response that is associated with increased DNA breakages and sensitivity of cells to DNA damaging agents, suggesting a DNA repair defect is associated. siRNA interrogation of key Cullin substrates show that CDT1, p21, and Claspin are involved in elevated DNA damage in the UBE2M knockdown cells. Therefore, UBE2M is required to maintain genome integrity by activating multiple Cullin ligases throughout the cell cycle.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction.

PubMed

Kanda, Yusuke; Osaki, Mitsuhiko; Okada, Futoshi

2017-04-19

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis.

Tobacco nitrosamines as culprits in disease: mechanisms reviewed

PubMed Central

Yalcin, Emine

2016-01-01

The link between tobacco abuse and cancer is well-established. However, emerging data indicate that toxins in tobacco smoke cause cellular injury due to enhanced toxic/metabolic effects of metabolites, disruption of intracellular signaling mechanisms, and formation of DNA, protein, and lipid adducts that impair function and promote oxidative stress and inflammation. These effects of smoking, which are largely non-carcinogenic, can be produced by tobacco-specific nitrosamines and their metabolites. These factors could account for the increased rates of neurodegeneration and insulin resistance diseases among smokers. Herein, we review nicotine and tobacco-specific nitrosamine metabolism, mechanisms of adduct formation, DNA damage, mutagenesis, and potential mechanisms of disease. PMID:26767836

Enhanced reactive oxygen species overexpression by CuO nanoparticles in poorly differentiated hepatocellular carcinoma cells

NASA Astrophysics Data System (ADS)

Kung, Mei-Lang; Hsieh, Shu-Ling; Wu, Chih-Chung; Chu, Tian-Huei; Lin, Yu-Chun; Yeh, Bi-Wen; Hsieh, Shuchen

2015-01-01

Copper oxide nanoparticles (CuO NPs) are known to exhibit toxic effects on a variety of cell types and organs. To determine the oxidative impact of CuO NPs on hepatocellular carcinoma (HCC) cells, well-differentiated (HepG2) and poorly differentiated (SK-Hep-1) cells were exposed to CuO NPs. Cell viability assay showed that the median inhibition concentration (IC50) for SK-Hep-1 and HepG2 cells was 25 μg ml-1 and 85 μg ml-1, respectively. Cellular fluorescence intensity using DCFH-DA staining analysis revealed significant intracellular reactive oxygen species (ROS) generation of up to 242% in SK-Hep-1 cells, compared with 86% in HepG2 cells. HPLC analysis demonstrated that a CuO NP treatment caused cellular GSH depletion of 58% and a GSH/GSSG ratio decrease to ~0.1 in SK-Hep-1 cells. The oxidative stress caused by enhanced superoxide anion production was observed in both HepG2 (146%) and SK-Hep-1 (192%) cells. The Griess assay verified that CuO NPs induced NO production (170%) in SK-Hep-1 cells. Comet assay and western blot further demonstrated that CuO NPs induced severe DNA strand breakage (70%) in SK-Hep-1 cells and caused DNA damage via increased γ-H2AX levels. These results suggest that well-differentiated HepG2 cells possess a robust antioxidant defense system against CuO NP-induced ROS stress and exhibit more tolerance to oxidative stress. Conversely, poorly differentiated SK-Hep-1 cells exhibited a deregulated antioxidant defense system that allowed accumulation of CuO NP-induced ROS and resulted in severe cytotoxicity.Copper oxide nanoparticles (CuO NPs) are known to exhibit toxic effects on a variety of cell types and organs. To determine the oxidative impact of CuO NPs on hepatocellular carcinoma (HCC) cells, well-differentiated (HepG2) and poorly differentiated (SK-Hep-1) cells were exposed to CuO NPs. Cell viability assay showed that the median inhibition concentration (IC50) for SK-Hep-1 and HepG2 cells was 25 μg ml-1 and 85 μg ml-1, respectively. Cellular fluorescence intensity using DCFH-DA staining analysis revealed significant intracellular reactive oxygen species (ROS) generation of up to 242% in SK-Hep-1 cells, compared with 86% in HepG2 cells. HPLC analysis demonstrated that a CuO NP treatment caused cellular GSH depletion of 58% and a GSH/GSSG ratio decrease to ~0.1 in SK-Hep-1 cells. The oxidative stress caused by enhanced superoxide anion production was observed in both HepG2 (146%) and SK-Hep-1 (192%) cells. The Griess assay verified that CuO NPs induced NO production (170%) in SK-Hep-1 cells. Comet assay and western blot further demonstrated that CuO NPs induced severe DNA strand breakage (70%) in SK-Hep-1 cells and caused DNA damage via increased γ-H2AX levels. These results suggest that well-differentiated HepG2 cells possess a robust antioxidant defense system against CuO NP-induced ROS stress and exhibit more tolerance to oxidative stress. Conversely, poorly differentiated SK-Hep-1 cells exhibited a deregulated antioxidant defense system that allowed accumulation of CuO NP-induced ROS and resulted in severe cytotoxicity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05843g

Ultraviolet Radiation: Cellular Antioxidant Response and the Role of Ocular Aldehyde Dehydrogenase Enzymes

PubMed Central

Marchitti, Satori A.; Chen, Ying; Thompson, David C.; Vasiliou, Vasilis

2011-01-01

Solar ultraviolet radiation (UVR) exposes the human eye to near constant oxidative stress. Evidence suggests that UVR is the most important environmental insult leading to the development of a variety of ophthalmoheliosis disorders. UVR-induced reactive oxygen species are highly reactive with DNA, proteins and cellular membranes, resulting in cellular and tissue damage. Antioxidant defense systems present in ocular tissues function to combat reactive oxygen species and protect the eye from oxidative damage. Important enzymatic antioxidants are the superoxide dismutases, catalase, glutathione peroxidases, glutathione reductase and members of the aldehyde dehydrogenase (ALDH) superfamily. Glutathione, ascorbic and uric acids, α-tocopherol, NADPH and ferritin serve as small molecule, nonenzymatic antioxidants. Ocular tissues have high levels of these antioxidants which are essential for the maintenance of redox homeostasis in the eye and protection against oxidative damage. ALDH1A1 and ALDH3A1, present abundantly in the cornea and lens, have been shown to have unique roles in the defense against UVR and the downstream effects of oxidative stress. This review presents the properties and functions of ocular antioxidants that play critical roles in the cellular response to UVR exposure, including a focused discussion of the unique roles that the ALDH1A1 and ALDH3A1 enzymes have as multi-functional ocular antioxidants. PMID:21670692

Biological processing of dinuclear ruthenium complexes in eukaryotic cells.

PubMed

Li, Xin; Heimann, Kirsten; Dinh, Xuyen Thi; Keene, F Richard; Collins, J Grant

2016-10-20

The biological processing - mechanism of cellular uptake, effects on the cytoplasmic and mitochondrial membranes, intracellular sites of localisation and induction of reactive oxygen species - of two dinuclear polypyridylruthenium(ii) complexes has been examined in three eukaryotic cells lines. Flow cytometry was used to determine the uptake of [{Ru(phen)2}2{μ-bb12}](4+) (Rubb12) and [Ru(phen)2(μ-bb7)Ru(tpy)Cl](3+) {Rubb7-Cl, where phen = 1,10-phenanthroline, tpy = 2,2':6',2''-terpyridine and bbn = bis[4(4'-methyl-2,2'-bipyridyl)]-1,n-alkane} in baby hamster kidney (BHK), human embryonic kidney (HEK-293) and liver carcinoma (HepG2) cell lines. The results demonstrated that the major uptake mechanism for Rubb12 and Rubb7-Cl was active transport, although with a significant contribution from carrier-assisted diffusion for Rubb12 and passive diffusion for Rubb7-Cl. Flow cytometry coupled with Annexin V/TO-PRO-3 double-staining was used to compare cell death by membrane damage or apoptosis. Rubb12 induced significant direct membrane damage, particularly with HepG2 cells, while Rubb7-Cl caused considerably less membrane damage but induced greater levels of apoptosis. Confocal microscopy, coupled with JC-1 assays, demonstrated that Rubb12 depolarises the mitochondrial membrane, whereas Rubb7-Cl had a much smaller affect. Cellular localisation experiments indicated that Rubb12 did not accumulate in the mitochondria, whereas significant mitochondrial accumulation was observed for Rubb7-Cl. The effect of Rubb12 and Rubb7-Cl on intracellular superoxide dismutase activity showed that the ruthenium complexes could induce cell death via a reactive oxygen species-mediated pathway. The results of this study demonstrate that Rubb12 predominantly kills eukaryotic cells by damaging the cytoplasmic membrane. As this dinuclear ruthenium complex has been previously shown to exhibit greater toxicity towards bacteria than eukaryotic cells, the results of the present study suggest that metal-based cationic oligomers can achieve selective toxicity against bacteria, despite exhibiting a non-specific membrane damage mechanism of action.

Silver nanoparticles: correlating nanoparticle size and cellular uptake with genotoxicity

PubMed Central

Butler, Kimberly S.; Peeler, David J.; Casey, Brendan J.; Dair, Benita J.; Elespuru, Rosalie K.

2015-01-01

The focus of this research was to develop a better understanding of the pertinent physico-chemical properties of silver nanoparticles (AgNPs) that affect genotoxicity, specifically how cellular uptake influences a genotoxic cell response. The genotoxicity of AgNPs was assessed for three potential mechanisms: mutagenicity, clastogenicity and DNA strand-break-based DNA damage. Mutagenicity (reverse mutation assay) was assessed in five bacterial strains of Salmonella typhimurium and Echerichia coli, including TA102 that is sensitive to oxidative DNA damage. AgNPs of all sizes tested (10, 20, 50 and 100nm), along with silver nitrate (AgNO3), were negative for mutagenicity in bacteria. No AgNPs could be identified within the bacteria cells using transmission electron microscopy (TEM), indicating these bacteria lack the ability to actively uptake AgNPs 10nm or larger. Clastogenicity (flow cytometry-based micronucleus assay) and intermediate DNA damage (DNA strand breaks as measured in the Comet assay) were assessed in two mammalian white blood cell lines: Jurkat Clone E6-1 and THP-1. It was observed that micronucleus and Comet assay end points were inversely correlated with AgNP size, with smaller NPs inducing a more genotoxic response. TEM results indicated that AgNPs were confined within intracellular vesicles of mammalian cells and did not penetrate the nucleus. The genotoxicity test results and the effect of AgNO3 controls suggest that silver ions may be the primary, and perhaps only, cause of genotoxicity. Furthermore, since AgNO3 was not mutagenic in the gram-negative bacterial Ames strains tested, the lack of bacterial uptake of the AgNPs may not be the major reason for the lack of genotoxicity observed. PMID:25964273

Arsenite-induced autophagy is associated with proteotoxicity in human lymphoblastoid cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolt, Alicia M.; Zhao, Fei; Pacheco, Samantha

2012-10-15

Epidemiological studies of arsenic-exposed populations have provided evidence that arsenic exposure in humans is associated with immunosuppression. Previously, we have reported that arsenite-induced toxicity is associated with the induction of autophagy in human lymphoblastoid cell lines (LCL). Autophagy is a cellular process that functions in the degradation of damaged cellular components, including protein aggregates formed by misfolded or damaged proteins. Accumulation of misfolded or damaged proteins in the endoplasmic reticulum (ER) lumen causes ER stress and activates the unfolded protein response (UPR). In an effort to investigate the mechanism of autophagy induction by arsenite in the LCL model, we examinedmore » the potential contribution of ER stress and activation of the UPR. LCL exposed to sodium arsenite for 8-days induced expression of UPR-activated genes, including CHOP and GRP78, at the RNA and the protein level. Evidence for activation of the three arms of the UPR was observed. The arsenite-induced activation of the UPR was associated with an accumulation of protein aggregates containing p62 and LC3, proteins with established roles in the sequestration and autophagic clearance of protein aggregates. Taken together, these data provide evidence that arsenite-induced autophagy is associated with the generation of ER stress, activation of the UPR, and formation of protein aggregates that may be targeted to the lysosome for degradation. -- Highlights: ► Arsenite induces endoplasmic reticulum stress and the unfolded protein response. ► Arsenite induces the formation of protein aggregates that contain p62 and LC3-II. ► Time-course data suggests that arsenite-induced autophagy precedes ER stress.« less

DDX3 DEAD-box RNA helicase plays a central role in mitochondrial protein quality control in Leishmania

PubMed Central

Padmanabhan, Prasad Kottayil; Zghidi-Abouzid, Ouafa; Samant, Mukesh; Dumas, Carole; Aguiar, Bruno Guedes; Estaquier, Jerome; Papadopoulou, Barbara

2016-01-01

DDX3 is a highly conserved member of ATP-dependent DEAD-box RNA helicases with multiple functions in RNA metabolism and cellular signaling. Here, we describe a novel function for DDX3 in regulating the mitochondrial stress response in the parasitic protozoan Leishmania. We show that genetic inactivation of DDX3 leads to the accumulation of mitochondrial reactive oxygen species (ROS) associated with a defect in hydrogen peroxide detoxification. Upon stress, ROS production is greatly enhanced, causing mitochondrial membrane potential loss, mitochondrial fragmentation, and cell death. Importantly, this phenotype is exacerbated upon oxidative stress in parasites forced to use the mitochondrial oxidative respiratory machinery. Furthermore, we show that in the absence of DDX3, levels of major components of the unfolded protein response as well as of polyubiquitinated proteins increase in the parasite, particularly in the mitochondrion, as an indicator of mitochondrial protein damage. Consistent with these findings, immunoprecipitation and mass-spectrometry studies revealed potential interactions of DDX3 with key components of the cellular stress response, particularly the antioxidant response, the unfolded protein response, and the AAA-ATPase p97/VCP/Cdc48, which is essential in mitochondrial protein quality control by driving proteosomal degradation of polyubiquitinated proteins. Complementation studies using DDX3 deletion mutants lacking conserved motifs within the helicase core support that binding of DDX3 to ATP is essential for DDX3's function in mitochondrial proteostasis. As a result of the inability of DDX3-depleted Leishmania to recover from ROS damage and to survive various stresses in the host macrophage, parasite intracellular development was impaired. Collectively, these observations support a central role for the Leishmania DDX3 homolog in preventing ROS-mediated damage and in maintaining mitochondrial protein quality control. PMID:27735940

Loss of pericyte smoothened activity in mice with genetic deficiency of leptin.

PubMed

Xie, Guanhua; Swiderska-Syn, Marzena; Jewell, Mark L; Machado, Mariana Verdelho; Michelotti, Gregory A; Premont, Richard T; Diehl, Anna Mae

2017-04-20

Obesity is associated with multiple diseases, but it is unclear how obesity promotes progressive tissue damage. Recovery from injury requires repair, an energy-expensive process that is coupled to energy availability at the cellular level. The satiety factor, leptin, is a key component of the sensor that matches cellular energy utilization to available energy supplies. Leptin deficiency signals energy depletion, whereas activating the Hedgehog pathway drives energy-consuming activities. Tissue repair is impaired in mice that are obese due to genetic leptin deficiency. Tissue repair is also blocked and obesity enhanced by inhibiting Hedgehog activity. We evaluated the hypothesis that loss of leptin silences Hedgehog signaling in pericytes, multipotent leptin-target cells that regulate a variety of responses that are often defective in obesity, including tissue repair and adipocyte differentiation. We found that pericytes from liver and white adipose tissue require leptin to maintain expression of the Hedgehog co-receptor, Smoothened, which controls the activities of Hedgehog-regulated Gli transcription factors that orchestrate gene expression programs that dictate pericyte fate. Smoothened suppression prevents liver pericytes from being reprogrammed into myofibroblasts, but stimulates adipose-derived pericytes to become white adipocytes. Progressive Hedgehog pathway decay promotes senescence in leptin-deficient liver pericytes, which, in turn, generate paracrine signals that cause neighboring hepatocytes to become fatty and less proliferative, enhancing vulnerability to liver damage. Leptin-responsive pericytes evaluate energy availability to inform tissue construction by modulating Hedgehog pathway activity and thus, are at the root of progressive obesity-related tissue pathology. Leptin deficiency inhibits Hedgehog signaling in pericytes to trigger a pericytopathy that promotes both adiposity and obesity-related tissue damage.

Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) Regulates γ-Histone 2AX (γ-H2AX) Levels upon Ionizing Radiation*

PubMed Central

Neumayer, Gernot; Helfricht, Angela; Shim, Su Yeon; Le, Hoa Thi; Lundin, Cecilia; Belzil, Camille; Chansard, Mathieu; Yu, Yaping; Lees-Miller, Susan P.; Gruss, Oliver J.; van Attikum, Haico; Helleday, Thomas; Nguyen, Minh Dang

2012-01-01

The microtubule-associated protein targeting protein for Xenopus kinesin-like protein 2 (TPX2) plays a key role in spindle assembly and is required for mitosis in human cells. In interphase, TPX2 is actively imported into the nucleus to prevent its premature activity in microtubule organization. To date, no function has been assigned to nuclear TPX2. We now report that TPX2 plays a role in the cellular response to DNA double strand breaks induced by ionizing radiation. Loss of TPX2 leads to inordinately strong and transient accumulation of ionizing radiation-dependent Ser-139-phosphorylated Histone 2AX (γ-H2AX) at G0 and G1 phases of the cell cycle. This is accompanied by the formation of increased numbers of high intensity γ-H2AX ionizing radiation-induced foci. Conversely, cells overexpressing TPX2 have reduced levels of γ-H2AX after ionizing radiation. Consistent with a role for TPX2 in the DNA damage response, we found that the protein accumulates at DNA double strand breaks and associates with the mediator of DNA damage checkpoint 1 (MDC1) and the ataxia telangiectasia mutated (ATM) kinase, both key regulators of γ-H2AX amplification. Pharmacologic inhibition or depletion of ATM or MDC1, but not of DNA-dependent protein kinase (DNA-PK), antagonizes the γ-H2AX phenotype caused by TPX2 depletion. Importantly, the regulation of γ-H2AX signals by TPX2 is not associated with apoptosis or the mitotic functions of TPX2. In sum, our study identifies a novel and the first nuclear function for TPX2 in the cellular responses to DNA damage. PMID:23045526

ATM Protein Physically and Functionally Interacts with Proliferating Cell Nuclear Antigen to Regulate DNA Synthesis*

PubMed Central

Gamper, Armin M.; Choi, Serah; Matsumoto, Yoshihiro; Banerjee, Dibyendu; Tomkinson, Alan E.; Bakkenist, Christopher J.

2012-01-01

Ataxia telangiectasia (A-T) is a pleiotropic disease, with a characteristic hypersensitivity to ionizing radiation that is caused by biallelic mutations in A-T mutated (ATM), a gene encoding a protein kinase critical for the induction of cellular responses to DNA damage, particularly to DNA double strand breaks. A long known characteristic of A-T cells is their ability to synthesize DNA even in the presence of ionizing radiation-induced DNA damage, a phenomenon termed radioresistant DNA synthesis. We previously reported that ATM kinase inhibition, but not ATM protein disruption, blocks sister chromatid exchange following DNA damage. We now show that ATM kinase inhibition, but not ATM protein disruption, also inhibits DNA synthesis. Investigating a potential physical interaction of ATM with the DNA replication machinery, we found that ATM co-precipitates with proliferating cell nuclear antigen (PCNA) from cellular extracts. Using bacterially purified ATM truncation mutants and in vitro translated PCNA, we showed that the interaction is direct and mediated by the C terminus of ATM. Indeed, a 20-amino acid region close to the kinase domain is sufficient for strong binding to PCNA. This binding is specific to ATM, because the homologous regions of other PIKK members, including the closely related kinase A-T and Rad3-related (ATR), did not bind PCNA. ATM was found to bind two regions in PCNA. To examine the functional significance of the interaction between ATM and PCNA, we tested the ability of ATM to stimulate DNA synthesis by DNA polymerase δ, which is implicated in both DNA replication and DNA repair processes. ATM was observed to stimulate DNA polymerase activity in a PCNA-dependent manner. PMID:22362778

Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli.

PubMed

Bhat, Supriya V; Kamencic, Belma; Körnig, André; Shahina, Zinnat; Dahms, Tanya E S

2018-01-01

Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro , and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force - laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage.

UVA phototransduction drives early melanin synthesis in human melanocytes.

PubMed

Wicks, Nadine L; Chan, Jason W; Najera, Julia A; Ciriello, Jonathan M; Oancea, Elena

2011-11-22

Exposure of human skin to solar ultraviolet radiation (UVR), a powerful carcinogen [1] comprising ~95% ultraviolet A (UVA) and ~5% ultraviolet B (UVB) at the Earth's surface, promotes melanin synthesis in epidermal melanocytes [2, 3], which protects skin from DNA damage [4, 5]. UVB causes DNA lesions [6] that lead to transcriptional activation of melanin-producing enzymes, resulting in delayed skin pigmentation within days [7]. In contrast, UVA causes primarily oxidative damage [8] and leads to immediate pigment darkening (IPD) within minutes, via an unknown mechanism [9, 10]. No receptor protein directly mediating phototransduction in skin has been identified. Here we demonstrate that exposure of primary human epidermal melanocytes (HEMs) to UVA causes calcium mobilization and early melanin synthesis. Calcium responses were abolished by treatment with G protein or phospholipase C (PLC) inhibitors or by depletion of intracellular calcium stores. We show that the visual photopigment rhodopsin [11] is expressed in HEMs and contributes to UVR phototransduction. Upon UVR exposure, significant melanin production was measured within one hour; cellular melanin continued to increase in a retinal- and calcium-dependent manner up to 5-fold after 24 hr. Our findings identify a novel UVA-sensitive signaling pathway in melanocytes that leads to calcium mobilization and melanin synthesis and may underlie the mechanism of IPD in human skin. Copyright © 2011 Elsevier Ltd. All rights reserved.

Methamphetamine Accelerates Cellular Senescence through Stimulation of De Novo Ceramide Biosynthesis

PubMed Central

Astarita, Giuseppe; Avanesian, Agnesa; Grimaldi, Benedetto; Realini, Natalia; Justinova, Zuzana; Panlilio, Leight V.; Basit, Abdul; Piomelli, Daniele

2015-01-01

Methamphetamine is a highly addictive psychostimulant that causes profound damage to the brain and other body organs. Post mortem studies of human tissues have linked the use of this drug to diseases associated with aging, such as coronary atherosclerosis and pulmonary fibrosis, but the molecular mechanism underlying these findings remains unknown. Here we used functional lipidomics and transcriptomics experiments to study abnormalities in lipid metabolism in select regions of the brain and, to a greater extent, peripheral organs and tissues of rats that self-administered methamphetamine. Experiments in various cellular models (primary mouse fibroblasts and myotubes) allowed us to investigate the molecular mechanisms of systemic inflammation and cellular aging related to methamphetamine abuse. We report now that methamphetamine accelerates cellular senescence and activates transcription of genes involved in cell-cycle control and inflammation by stimulating production of the sphingolipid messenger ceramide. This pathogenic cascade is triggered by reactive oxygen species, likely generated through methamphetamine metabolism via cytochrome P450, and involves the recruitment of nuclear factor-κB (NF-κB) to induce expression of enzymes in the de novo pathway of ceramide biosynthesis. Inhibitors of NF-κB signaling and ceramide formation prevent methamphetamine-induced senescence and systemic inflammation in rats self-administering the drug, attenuating their health deterioration. The results suggest new therapeutic strategies to reduce the adverse consequences of methamphetamine abuse and improve effectiveness of abstinence treatments. PMID:25671639

To Be or Not to Be: Controlling Cellular Suicide | Center for Cancer Research

Cancer.gov

When a cell is damaged and can no longer function properly, a complex series of molecular steps is triggered that allows it to die in a controlled manner. This cellular suicide is called programmed cell death, or apoptosis.

Knockdown of cytosolic NADP(+) -dependent isocitrate dehydrogenase enhances MPP(+) -induced oxidative injury in PC12 cells.

PubMed

Yang, Eun Sun; Park, Jeen-Woo

2011-05-01

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its toxic metabolite 1-methyl-4-phenylpyridium ion (MPP(+)) have been shown to induce Parkinson's disease-like symptoms as well as neurotoxicity in humans and animal species. Recently, we reported that maintenance of redox balance and cellular defense against oxidative damage are primary functions of the novel antioxidant enzyme cytosolic NADP(+) -dependent isocitrate dehydrogenase (IDPc). In this study, we examined the role of IDPc in cellular defense against MPP(+) -induced oxidative injury using PC12 cells transfected with IDPc small interfering RNA (siRNA). Our results demonstrate that MPP(+) -mediated disruption of cellular redox status, oxidative damage to cells, and apoptotic cell death were significantly enhanced by knockdown of IDPc.

Comparative analysis of different laser systems to study cellular responses to DNA damage in mammalian cells

PubMed Central

Kong, Xiangduo; Mohanty, Samarendra K.; Stephens, Jared; Heale, Jason T.; Gomez-Godinez, Veronica; Shi, Linda Z.; Kim, Jong-Soo; Yokomori, Kyoko; Berns, Michael W.

2009-01-01

Proper recognition and repair of DNA damage is critical for the cell to protect its genomic integrity. Laser microirradiation ranging in wavelength from ultraviolet A (UVA) to near-infrared (NIR) can be used to induce damage in a defined region in the cell nucleus, representing an innovative technology to effectively analyze the in vivo DNA double-strand break (DSB) damage recognition process in mammalian cells. However, the damage-inducing characteristics of the different laser systems have not been fully investigated. Here we compare the nanosecond nitrogen 337 nm UVA laser with and without bromodeoxyuridine (BrdU), the nanosecond and picosecond 532 nm green second-harmonic Nd:YAG, and the femtosecond NIR 800 nm Ti:sapphire laser with regard to the type(s) of damage and corresponding cellular responses. Crosslinking damage (without significant nucleotide excision repair factor recruitment) and single-strand breaks (with corresponding repair factor recruitment) were common among all three wavelengths. Interestingly, UVA without BrdU uniquely produced base damage and aberrant DSB responses. Furthermore, the total energy required for the threshold H2AX phosphorylation induction was found to vary between the individual laser systems. The results indicate the involvement of different damage mechanisms dictated by wavelength and pulse duration. The advantages and disadvantages of each system are discussed. PMID:19357094