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Sample records for regulates cardiomyocyte growth

  1. Myostatin regulates cardiomyocyte growth through modulation of Akt signaling.

    PubMed

    Morissette, Michael R; Cook, Stuart A; Foo, ShiYin; McKoy, Godfrina; Ashida, Noboru; Novikov, Mikhail; Scherrer-Crosbie, Marielle; Li, Ling; Matsui, Takashi; Brooks, Gavin; Rosenzweig, Anthony

    2006-07-07

    Myostatin is a highly conserved, potent negative regulator of skeletal muscle hypertrophy in many species, from rodents to humans, although its mechanisms of action are incompletely understood. Transcript profiling of hearts from a genetic model of cardiac hypertrophy revealed dramatic upregulation of myostatin, not previously recognized to play a role in the heart. Here we show that myostatin abrogates the cardiomyocyte growth response to phenylephrine in vitro through inhibition of p38 and the serine-threonine kinase Akt, a critical determinant of cell size in many species from drosophila to mammals. Evaluation of male myostatin-null mice revealed that their cardiomyocytes and hearts overall were slightly smaller at baseline than littermate controls but exhibited more exuberant growth in response to chronic phenylephrine infusion. The increased cardiac growth in myostatin-null mice corresponded with increased p38 phosphorylation and Akt activation in vivo after phenylephrine treatment. Together, these data demonstrate that myostatin is dynamically regulated in the heart and acts more broadly than previously appreciated to regulate growth of multiple types of striated muscle.

  2. Regulation of cardiomyocyte autophagy by calcium.

    PubMed

    Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo-Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F G; Hill, Joseph A; Lavandero, Sergio

    2016-04-15

    Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy.

  3. DYRK2 Negatively Regulates Cardiomyocyte Growth by Mediating Repressor Function of GSK-3β on eIF2Bε

    PubMed Central

    Hagenmueller, Marco; Streit, Marcus R.; Malekar, Pratima; Riffel, Johannes H.; Buss, Sebastian J.; Weiss, Karl H.; Sadoshima, Junichi; Katus, Hugo A.; Hardt, Stefan E.

    2013-01-01

    Background A prerequisite of hypertrophic response of the myocardium is an increase in protein synthesis. A central regulator of translation initiation is Eukaryotic initiation factor 2B (eIF2B). Here we assessed the hypothesis that regulation of protein synthesis via eIF2Bε is essential to cardiac hypertrophic response in vivo. Methods Two transgenic mouse lines were generated with cardiac restricted overexpression of eIF2Bε or its mutant eIF2Bε-eIFS535A, which cannot be inactivated by phosphorylation through GSK-3β. Results (1) Under baseline conditions eIF2Bε transgenic mice showed no difference in cardiac phenotype compared to wild type, whereas in the mutant eIF2Bε-S535A an increase in LV/tibia length (7.5±0.4 mg/mm vs. 6.2±0.2 mg/mm, p<0.001) and cardiomyocyte cross sectional area (13004±570 vs. 10843±347 RU, p<0.01) was observed. (2) Cardiac overexpression of eIF2Bε did not change the response of the heart to pathologic stress induced by chronic isoproterenol treatment. (3) Cardiac overexpression of the eIF2Bε transgene was followed by overexpression of DYRK2 which is known to prime the inhibitory action of GSK-3β on eIF2Bε, while DYRK1A and GSK-3β itself were not increased. (4) In C57BL/6 mice after 48 h of isoproterenol-stimulation or aortic banding, eIF2Bε was increased and DYRK2 was concomitantly decreased. (5) In line with these in vivo findings, siRNA knockdown of DYRK2 in cultured cardiomyocytes resulted in decreased levels of p(S535)- eIF2Bε, (6) whereas adenoviral induced overexpression of DYRK2 was accompanied by clearly increased phosphorylation of eIF2Bε, indicating a coordinated response pattern (7) Adenoviral induced overexpression of DYRK2 leads to significantly reduced cardiomyocyte size and diminishes hypertrophic response to adrenergic stimulation. Conclusions The interaction of GSK-3β and its priming kinase DYRK2 regulate the activity of eIF2Bε in cardiac myocytes. DYRK2 is a novel negative regulator of cardiomyocyte

  4. Proteolysis regulates cardiomyocyte maturation and tissue integration

    PubMed Central

    Fukuda, Ryuichi; Gunawan, Felix; Beisaw, Arica; Jimenez-Amilburu, Vanesa; Maischein, Hans-Martin; Kostin, Sawa; Kawakami, Koichi; Stainier, Didier Y. R.

    2017-01-01

    Tissue integrity is critical for organ formation and function. During heart development, cardiomyocytes differentiate and integrate to form a coherent tissue that contracts synchronously. However, the molecular mechanisms regulating cardiac tissue integrity are poorly understood. Here we show that proteolysis, via the E3 ubiquitin ligase ASB2, regulates cardiomyocyte maturation and tissue integrity. Cardiomyocytes in asb2b zebrafish mutants fail to terminally differentiate, resulting in reduced cardiac contractility and output. Mosaic analyses reveal a cell-autonomous requirement for Asb2b in cardiomyocytes for their integration as asb2b mutant cardiomyocytes are unable to meld into wild-type myocardial tissue. In vitro and in vivo data indicate that ASB2 negatively regulates TCF3, a bHLH transcription factor. TCF3 must be degraded for cardiomyocyte maturation, as TCF3 gain-of-function causes a number of phenotypes associated with cardiomyocyte dedifferentiation. Overall, our results show that proteolysis has an important role in cardiomyocyte maturation and the formation of a coherent myocardial tissue. PMID:28211472

  5. The Heparan Sulfate Proteoglycan Glypican-6 Is Upregulated in the Failing Heart, and Regulates Cardiomyocyte Growth through ERK1/2 Signaling

    PubMed Central

    Melleby, Arne O.; Strand, Mari E.; Romaine, Andreas; Herum, Kate M.; Skrbic, Biljana; Dahl, Christen P.; Sjaastad, Ivar; Fiane, Arnt E.; Filmus, Jorge; Christensen, Geir; Lunde, Ida G.

    2016-01-01

    Pressure overload is a frequent cause of heart failure. Heart failure affects millions of patients worldwide and is a major cause of morbidity and mortality. Cell surface proteoglycans are emerging as molecular players in cardiac remodeling, and increased knowledge about their regulation and function is needed for improved understanding of cardiac pathogenesis. Here we investigated glypicans (GPC1-6), a family of evolutionary conserved heparan sulfate proteoglycans anchored to the extracellular leaflet of the cell membrane, in experimental and clinical heart failure, and explored the function of glypican-6 in cardiac cells in vitro. In mice subjected to pressure overload by aortic banding (AB), we observed elevated glypican-6 levels during hypertrophic remodeling and dilated, end-stage heart failure. Consistently, glypican-6 mRNA was elevated in left ventricular myocardium from explanted hearts of patients with end-stage, dilated heart failure with reduced ejection fraction. Glypican-6 levels correlated negatively with left ventricular ejection fraction in patients, and positively with lung weight after AB in mice. Glypican-6 mRNA was expressed in both cardiac fibroblasts and cardiomyocytes, and the corresponding protein displayed different sizes in the two cell types due to tissue-specific glycanation. Importantly, adenoviral overexpression of glypican-6 in cultured cardiomyocytes increased protein synthesis and induced mRNA levels of the pro-hypertrophic signature gene ACTA1 and the hypertrophy and heart failure signature genes encoding natriuretic peptides, NPPA and NPPB. Overexpression of GPC6 induced ERK1/2 phosphorylation, and co-treatment with the ERK inhibitor U0126 attenuated the GPC6-induced increase in NPPA, NPPB and protein synthesis. In conclusion, our data suggests that glypican-6 plays a role in clinical and experimental heart failure progression by regulating cardiomyocyte growth through ERK signaling. PMID:27768722

  6. Innervating sympathetic neurons regulate heart size and the timing of cardiomyocyte cell cycle withdrawal.

    PubMed

    Kreipke, R E; Birren, S J

    2015-12-01

    Sympathetic drive to the heart is a key modulator of cardiac function and interactions between heart tissue and innervating sympathetic fibres are established early in development. Significant innervation takes place during postnatal heart development, a period when cardiomyocytes undergo a rapid transition from proliferative to hypertrophic growth. The question of whether these innervating sympathetic fibres play a role in regulating the modes of cardiomyocyte growth was investigated using 6-hydroxydopamine (6-OHDA) to abolish early sympathetic innervation of the heart. Postnatal chemical sympathectomy resulted in rats with smaller hearts, indicating that heart growth is regulated by innervating sympathetic fibres during the postnatal period. In vitro experiments showed that sympathetic interactions resulted in delays in markers of cardiomyocyte maturation, suggesting that changes in the timing of the transition from hyperplastic to hypertrophic growth of cardiomyocytes could underlie changes in heart size in the sympathectomized animals. There was also an increase in the expression of Meis1, which has been linked to cardiomyocyte cell cycle withdrawal, suggesting that sympathetic signalling suppresses cell cycle withdrawal. This signalling involves β-adrenergic activation, which was necessary for sympathetic regulation of cardiomyocyte proliferation and hypertrophy. The effect of β-adrenergic signalling on cardiomyocyte hypertrophy underwent a developmental transition. While young postnatal cardiomyocytes responded to isoproterenol (isoprenaline) with a decrease in cell size, mature cardiomyocytes showed an increase in cell size in response to the drug. Together, these results suggest that early sympathetic effects on proliferation modulate a key transition between proliferative and hypertrophic growth of the heart and contribute to the sympathetic regulation of adult heart size.

  7. Nerves Regulate Cardiomyocyte Proliferation and Heart Regeneration.

    PubMed

    Mahmoud, Ahmed I; O'Meara, Caitlin C; Gemberling, Matthew; Zhao, Long; Bryant, Donald M; Zheng, Ruimao; Gannon, Joseph B; Cai, Lei; Choi, Wen-Yee; Egnaczyk, Gregory F; Burns, Caroline E; Burns, C Geoffrey; MacRae, Calum A; Poss, Kenneth D; Lee, Richard T

    2015-08-24

    Some organisms, such as adult zebrafish and newborn mice, have the capacity to regenerate heart tissue following injury. Unraveling the mechanisms of heart regeneration is fundamental to understanding why regeneration fails in adult humans. Numerous studies have revealed that nerves are crucial for organ regeneration, thus we aimed to determine whether nerves guide heart regeneration. Here, we show using transgenic zebrafish that inhibition of cardiac innervation leads to reduction of myocyte proliferation following injury. Specifically, pharmacological inhibition of cholinergic nerve function reduces cardiomyocyte proliferation in the injured hearts of both zebrafish and neonatal mice. Direct mechanical denervation impairs heart regeneration in neonatal mice, which was rescued by the administration of neuregulin 1 (NRG1) and nerve growth factor (NGF) recombinant proteins. Transcriptional analysis of mechanically denervated hearts revealed a blunted inflammatory and immune response following injury. These findings demonstrate that nerve function is required for both zebrafish and mouse heart regeneration.

  8. Timing of cardiomyocyte growth, maturation, and attrition in perinatal sheep

    PubMed Central

    Jonker, Sonnet S.; Louey, Samantha; Giraud, George D.; Thornburg, Kent L.; Faber, J. Job

    2015-01-01

    Studies in altricial rodents attribute dramatic changes in perinatal cardiomyocyte growth, maturation, and attrition to stimuli associated with birth. Our purpose was to determine whether birth is a critical trigger controlling perinatal cardiomyocyte growth, maturation and attrition in a precocial large mammal, sheep (Ovis aries). Hearts from 0–61 d postnatal lambs were dissected or enzymatically dissociated. Cardiomyocytes were measured by micromorphometry, cell cycle activity assessed by immunohistochemistry, and nuclear number counted after DNA staining. Integration of this new data with published fetal data from our laboratory demonstrate that a newly appreciated >30% decrease in myocyte number occurred in the last 10 d of gestation (P < 0.0005) concomitant with an increase in cleaved poly (ADP-ribose) polymerase 1 (P < 0.05), indicative of apoptosis. Bisegmental linear regressions show that most changes in myocyte growth kinetics occur before birth (median = 15.2 d; P < 0.05). Right ventricular but not left ventricular cell number increases in the neonate, by 68% between birth and 60 d postnatal (P = 0.028). We conclude that in sheep few developmental changes in cardiomyocytes result from birth, excepting the different postnatal degrees of free wall hypertrophy between the ventricles. Furthermore, myocyte number is reduced in both ventricles immediately before term, but proliferation increases myocyte number in the neonatal right ventricle.—Jonker, S. S., Louey, S., Giraud, G. D., Thornburg, K. L., Faber, J. J. Timing of cardiomyocyte growth, maturation, and attrition in perinatal sheep. PMID:26139099

  9. AMPK and substrate availability regulate creatine transport in cultured cardiomyocytes.

    PubMed

    Darrabie, Marcus D; Arciniegas, Antonio Jose Luis; Mishra, Rajashree; Bowles, Dawn E; Jacobs, Danny O; Santacruz, Lucia

    2011-05-01

    Profound alterations in myocellular creatine and phosphocreatine levels are observed during human heart failure. To maintain its intracellular creatine stores, cardiomyocytes depend upon a cell membrane creatine transporter whose regulation is not clearly understood. Creatine transport capacity in the intact heart is modulated by substrate availability, and it is reduced in the failing myocardium, likely adding to the energy imbalance that characterizes heart failure. AMPK, a key regulator of cellular energy homeostasis, acts by switching off energy-consuming pathways in favor of processes that generate energy. Our objective was to determine the effects of substrate availability and AMPK activation on creatine transport in cardiomyocytes. We studied creatine transport in rat neonatal cardiomyocytes and HL-1 cardiac cells expressing the human creatine transporter cultured in the presence of varying creatine concentrations and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR). Transport was enhanced in cardiomyocytes following incubation in creatine-depleted medium or AICAR. The changes in transport were due to alterations in V(max) that correlated with changes in total and cell surface creatine transporter protein content. Our results suggest a positive role for AMPK in creatine transport modulation for cardiomyocytes in culture.

  10. The intrinsic circadian clock within the cardiomyocyte directly regulates myocardial gene expression, metabolism, and contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology remains unknown. We hypothesized that the circadian clock within the cardiomyocyte plays a role in regulating myo...

  11. The intrinsic circadian clock within the cardiomyocyte directly regulates myocardial gene expression, metabolism, and contractile function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology remains unknown. We hypothesized that circadian clock within the cardiomyocyte plays a role in regulating myocardia...

  12. Calcium-mediated histone modifications regulate alternative splicing in cardiomyocytes.

    PubMed

    Sharma, Alok; Nguyen, Hieu; Geng, Cuiyu; Hinman, Melissa N; Luo, Guangbin; Lou, Hua

    2014-11-18

    In cardiomyocytes, calcium is known to control gene expression at the level of transcription, whereas its role in regulating alternative splicing has not been explored. Here we report that, in mouse primary or embryonic stem cell-derived cardiomyocytes, increased calcium levels induce robust and reversible skipping of several alternative exons from endogenously expressed genes. Interestingly, we demonstrate a calcium-mediated splicing regulatory mechanism that depends on changes of histone modifications. Specifically, the regulation occurs through changes in calcium-responsive kinase activities that lead to alterations in histone modifications and subsequent changes in the transcriptional elongation rate and exon skipping. We demonstrate that increased intracellular calcium levels lead to histone hyperacetylation along the body of the genes containing calcium-responsive alternative exons by disrupting the histone deacetylase-to-histone acetyltransferase balance in the nucleus. Consequently, the RNA polymerase II elongation rate increases significantly on those genes, resulting in skipping of the alternative exons. These studies reveal a mechanism by which calcium-level changes in cardiomyocytes impact on the output of gene expression through altering alternative pre-mRNA splicing patterns.

  13. mTORC1 and mTORC2 play different roles in regulating cardiomyocyte differentiation from embryonic stem cells.

    PubMed

    Zheng, Bei; Wang, Jiadan; Tang, Leilei; Shi, Jiana; Zhu, Danyan

    2017-01-01

    Mammalian target of rapamycin (mTOR) is a serine/threonine kinase and functions through two distinct complexes, mTOR complex 1 (mTORC1) and complex 2 (mTORC2), with their key components Raptor and Rictor, to play crucial roles in cellular survival and growth. However, the roles of mTORC1 and mTORC2 in regulating cardiomyocyte differentiation from mouse embryonic stem (mES) cells are not clear. In this study, we performed Raptor or Rictor knockdown experiments to investigate the roles of mTORC1 and mTORC2 in cardiomyocyte differentiation. Ablation of Raptor markedly increased the number of cardiomyocytes derived from mES cells with well-organized myofilaments. Expression levels of brachyury (mesoderm protein), Nkx2.5 (cardiac progenitor cell protein), and α-Actinin (cardiomyocyte marker) were increased in Raptor knockdown cells. In contrast, loss of Rictor prevented cardiomyocyte differentiation. The dual ablation of Raptor and Rictor also decreased the number of cardiomyocytes. The two complexes exerted a regulatory mechanism in such a manner that knockdown of Raptor/mTORC1 resulted in a decreased phosphorylation of Rictor (Thr1135), which subsequently activated Rictor/mTORC2 in the differentiation of mES cells into cardiomyocytes. In conclusion, mTORC1 and mTORC2 played different roles in cardiomyocyte differentiation from mES cells in vitro. The activation of Rictor/mTORC2 was critical for facilitating cardiomyocyte differentiation from mES cells. Thus, this complex may be a promising target for regulating myocardial differentiation from embryonic stem cells or induced pluripotent stem cells.

  14. Regulation of myoglobin in hypertrophied rat cardiomyocytes in experimental pulmonary hypertension.

    PubMed

    Peters, E L; Offringa, C; Kos, D; Van der Laarse, W J; Jaspers, R T

    2016-10-01

    A major problem in chronic heart failure is the inability of hypertrophied cardiomyocytes to maintain the required power output. A Hill-type oxygen diffusion model predicts that oxygen supply is limiting in hypertrophied cardiomyocytes at maximal rates of oxygen consumption and that this limitation can be reduced by increasing the myoglobin (Mb) concentration. We explored how cardiac hypertrophy, oxidative capacity, and Mb expression in right ventricular cardiomyocytes are regulated at the transcriptional and translational levels in an early stage of experimental pulmonary hypertension, in order to identify targets to improve the oxygen supply/demand ratio. Male Wistar rats were injected with monocrotaline to induce pulmonary hypertension (PH) and right ventricular heart failure. The messenger RNA (mRNA) expression levels per nucleus of growth factors insulin-like growth factor-1Ea (IGF-1Ea) and mechano growth factor (MGF) were higher in PH than in healthy controls, consistent with a doubling in cardiomyocyte cross-sectional area (CSA). Succinate dehydrogenase (SDH) activity was unaltered, indicating that oxidative capacity per cell increased. Although the Mb protein concentration was unchanged, Mb mRNA concentration was reduced. However, total RNA per nucleus was about threefold higher in PH rats versus controls, and Mb mRNA content expressed per nucleus was similar in the two groups. The increase in oxidative capacity without an increase in oxygen supply via Mb-facilitated diffusion caused a doubling of the critical extracellular oxygen tension required to prevent hypoxia (PO2crit). We conclude that Mb mRNA expression is not increased during pressure overload-induced right ventricular hypertrophy and that the increase in myoglobin content per myocyte is likely due to increased translation. We conclude that increasing Mb mRNA expression may be beneficial in the treatment of experimental PH.

  15. MicroRNA-122 regulates caspase-8 and promotes the apoptosis of mouse cardiomyocytes

    PubMed Central

    Zhang, Z.W.; Li, H.; Chen, S.S.; Li, Y.; Cui, Z.Y.; Ma, J.

    2017-01-01

    Cardiomyocyte apoptosis plays key roles in the pathogenesis of heart diseases such as myocardial infarction. MicroRNAs are important regulators of gene expression, which are also involved in the regulation of cardiomyocyte apoptosis. However, cardiomyocyte apoptosis regulated by microRNA (miR)-122 is largely unexplored. The aim of this study focused on the role of miR-122 in cardiomyocyte apoptosis. Cardiomyocytes were isolated from neonatal mice and primarily cultured. MiR-122 mimic and inhibitor were transfected to cardiomyocytes and verified by qRT-PCR. Cell viability and apoptosis post-transfection were assessed by MTT assay and flow cytometry, respectively. Changes in expression of caspase-8 were quantified by qRT-PCR and western blot. Results showed that miR-122 mimic and inhibitor successfully induced changes in miR-122 levels in cultured cardiomyocytes (P<0.01). MiR-122 overexpression suppressed viability and promoted apoptosis of cardiomyocytes (P<0.05), and miR-122 knockdown promoted cell viability and inhibited apoptosis (P<0.05). The mRNA and protein levels of caspase-8 were elevated by miR-122 overexpression (P<0.01) and reduced by miR-122 knockdown (P<0.001). These results suggest an inductive role of miR-122 in cardiomyocyte apoptosis, which may be related to its regulation on caspase-8. PMID:28177059

  16. Effect of hepatocyte growth factor and angiotensin II on rat cardiomyocyte hypertrophy

    PubMed Central

    Chen, Ai-Lan; Ou, Cai-Wen; He, Zhao-Chu; Liu, Qi-Cai; Dong, Qi; Chen, Min-Sheng

    2012-01-01

    Angiotensin II (Ang II) plays an important role in cardiomyocyte hypertrophy. The combined effect of hepatocyte growth factor (HGF) and Ang II on cardiomyocytes is unknown. The present study was designed to determine the effect of HGF on cardiomyocyte hypertrophy and to explore the combined effect of HGF and Ang II on cardiomyocyte hypertrophy. Primary cardiomyocytes were isolated from neonatal rat hearts and cultured in vitro. Cells were treated with Ang II (1 µM) alone, HGF (10 ng/mL) alone, and Ang II (1 µM) plus HGF (10 ng/mL) for 24, 48, and 72 h. The amount of [3H]-leucine incorporation was then measured to evaluate protein synthesis. The mRNA levels of β-myosin heavy chain and atrial natriuretic factor were determined by real-time PCR to evaluate the presence of fetal phenotypes of gene expression. The cell size of cardiomyocytes was also studied. Ang II (1 µM) increased cardiomyocyte hypertrophy. Similar to Ang II, treatment with 1 µM HGF promoted cardiomyocyte hypertrophy. Moreover, the combination of 1 µM Ang II and 10 ng/mL HGF clearly induced a combined pro-hypertrophy effect on cardiomyocytes. The present study demonstrates for the first time a novel, combined effect of HGF and Ang II in promoting cardiomyocyte hypertrophy. PMID:23044624

  17. Btg2 is a Negative Regulator of Cardiomyocyte Hypertrophy through a Decrease in Cytosolic RNA

    PubMed Central

    Masumura, Yuki; Higo, Shuichiro; Asano, Yoshihiro; Kato, Hisakazu; Yan, Yi; Ishino, Saki; Tsukamoto, Osamu; Kioka, Hidetaka; Hayashi, Takaharu; Shintani, Yasunori; Yamazaki, Satoru; Minamino, Tetsuo; Kitakaze, Masafumi; Komuro, Issei; Takashima, Seiji; Sakata, Yasushi

    2016-01-01

    Under hypertrophic stimulation, cardiomyocytes enter a hypermetabolic state and accelerate biomass accumulation. Although the molecular pathways that regulate protein levels are well-studied, the functional implications of RNA accumulation and its regulatory mechanisms in cardiomyocytes remain elusive. Here, we have elucidated the quantitative kinetics of RNA in cardiomyocytes through single cell imaging and c-Myc (Myc)-mediated hypermetabolic analytical model using cultured cardiomyocytes. Nascent RNA labeling combined with single cell imaging demonstrated that Myc protein significantly increased the amount of global RNA production per cardiomyocyte. Chromatin immunoprecipitation with high-throughput sequencing clarified that overexpressed Myc bound to a specific set of genes and recruits RNA polymerase II. Among these genes, we identified Btg2 as a novel target of Myc. Btg2 overexpression significantly reduced cardiomyocyte surface area. Conversely, shRNA-mediated knockdown of Btg2 accelerated adrenergic stimulus-induced hypertrophy. Using mass spectrometry analysis, we determined that Btg2 binds a series of proteins that comprise mRNA deadenylation complexes. Intriguingly, Btg2 specifically suppresses cytosolic, but not nuclear, RNA levels. Btg2 knockdown further enhances cytosolic RNA accumulation in cardiomyocytes under adrenergic stimulation, suggesting that Btg2 negatively regulates reactive hypertrophy by negatively regulating RNA accumulation. Our findings provide insight into the functional significance of the mechanisms regulating RNA levels in cardiomyocytes. PMID:27346836

  18. Regulation of cardiomyocyte signaling by RGS proteins: differential selectivity towards G proteins and susceptibility to regulation.

    PubMed

    Hao, Jianming; Michalek, Christina; Zhang, Wei; Zhu, Ming; Xu, Xiaomei; Mende, Ulrike

    2006-07-01

    Many signals that regulate cardiomyocyte growth, differentiation and function are mediated via heterotrimeric G proteins, which are under the control of RGS proteins (Regulators of G protein Signaling). Several RGS proteins are expressed in the heart, but so far little is known about their function and regulation. Using adenoviral gene transfer, we conducted the first comprehensive analysis of the capacity and selectivity of the major cardiac RGS proteins (RGS2-RGS5) to regulate central G protein-mediated signaling pathways in adult ventricular myocytes (AVM). All four RGS proteins potently inhibited Gq/11-mediated phospholipase C beta stimulation and cell growth (assessed in neonatal myocytes). Importantly, RGS2 selectively inhibited Gq/11 signaling, whereas RGS3, RGS4 and RGS5 had the capacity to regulate both Gq/11 and Gi/o signaling (carbachol-induced cAMP inhibition). Gs signaling was unaffected, and, contrary to reports in other cell lines, RGS2-RGS5 did not appear to regulate adenylate cyclase directly in AVM. Since RGS proteins can be highly regulated in their expression by many different stimuli, we also tested the hypothesis that RGS expression is subject to G protein-mediated regulation in AVM and determined the specificity with which enhanced G protein signaling alters endogenous RGS expression in AVM. RGS2 mRNA and protein were markedly but transiently up-regulated by enhanced Gq/11 signaling (alpha1-adrenergic stimulation or Galphaq* overexpression), possibly by a negative feedback mechanism. In contrast, the other negative regulators of Gq/11 signaling (RGS3-RGS5) were unchanged. Endogenous RGS2 (but not RGS3-RGS5) expression was also up-regulated in cells with enhanced AC signaling (beta-adrenergic or forskolin stimulation). Taken together, these findings suggest diverse roles of RGS proteins in regulating myocyte signaling. RGS2 emerged as the only selective and highly regulated inhibitor of Gq/11 signaling that could potentially become a promising

  19. Notch signaling regulates cardiomyocyte proliferation during zebrafish heart regeneration.

    PubMed

    Zhao, Long; Borikova, Asya L; Ben-Yair, Raz; Guner-Ataman, Burcu; MacRae, Calum A; Lee, Richard T; Burns, C Geoffrey; Burns, Caroline E

    2014-01-28

    The human heart's failure to replace ischemia-damaged myocardium with regenerated muscle contributes significantly to the worldwide morbidity and mortality associated with coronary artery disease. Remarkably, certain vertebrate species, including the zebrafish, achieve complete regeneration of amputated or injured myocardium through the proliferation of spared cardiomyocytes. Nonetheless, the genetic and cellular determinants of natural cardiac regeneration remain incompletely characterized. Here, we report that cardiac regeneration in zebrafish relies on Notch signaling. Following amputation of the zebrafish ventricular apex, Notch receptor expression becomes activated specifically in the endocardium and epicardium, but not the myocardium. Using a dominant negative approach, we discovered that suppression of Notch signaling profoundly impairs cardiac regeneration and induces scar formation at the amputation site. We ruled out defects in endocardial activation, epicardial activation, and dedifferentiation of compact myocardial cells as causative for the regenerative failure. Furthermore, coronary endothelial tubes, which we lineage traced from preexisting endothelium in wild-type hearts, formed in the wound despite the myocardial regenerative failure. Quantification of myocardial proliferation in Notch-suppressed hearts revealed a significant decrease in cycling cardiomyocytes, an observation consistent with a noncell autonomous requirement for Notch signaling in cardiomyocyte proliferation. Unexpectedly, hyperactivation of Notch signaling also suppressed cardiomyocyte proliferation and heart regeneration. Taken together, our data uncover the exquisite sensitivity of regenerative cardiomyocyte proliferation to perturbations in Notch signaling.

  20. Cardiomyocyte Regulation of Systemic Lipid Metabolism by the Apolipoprotein B-Containing Lipoproteins in Drosophila

    PubMed Central

    Ishikawa, Zachary

    2017-01-01

    The heart has emerged as an important organ in the regulation of systemic lipid homeostasis; however, the underlying mechanism remains poorly understood. Here, we show that Drosophila cardiomyocytes regulate systemic lipid metabolism by producing apolipoprotein B-containing lipoproteins (apoB-lipoproteins), essential lipid carriers that are so far known to be generated only in the fat body. In a Drosophila genetic screen, we discovered that when haplo-insufficient, microsomal triglyceride transfer protein (mtp), required for the biosynthesis of apoB-lipoproteins, suppressed the development of diet-induced obesity. Tissue-specific inhibition of Mtp revealed that whereas knockdown of mtp only in the fat body decreases systemic triglyceride (TG) content on normal food diet (NFD) as expected, knockdown of mtp only in the cardiomyocytes also equally decreases systemic TG content on NFD, suggesting that the cardiomyocyte- and fat body-derived apoB-lipoproteins serve similarly important roles in regulating whole-body lipid metabolism. Unexpectedly, on high fat diet (HFD), knockdown of mtp in the cardiomyocytes, but not in fat body, protects against the gain in systemic TG levels. We further showed that inhibition of the Drosophila apoB homologue, apolipophorin or apoLpp, another gene essential for apoB-lipoprotein biosynthesis, affects systemic TG levels similarly to that of Mtp inhibition in the cardiomyocytes on NFD or HFD. Finally, we determined that HFD differentially alters Mtp and apoLpp expression in the cardiomyocytes versus the fat body, culminating in higher Mtp and apoLpp levels in the cardiomyocytes than in fat body and possibly underlying the predominant role of cardiomyocyte-derived apoB-lipoproteins in lipid metabolic regulation. Our findings reveal a novel and significant function of heart-mediated apoB-lipoproteins in controlling lipid homeostasis. PMID:28095410

  1. Hyperosmotic stress-dependent NFkappaB activation is regulated by reactive oxygen species and IGF-1 in cultured cardiomyocytes.

    PubMed

    Eisner, Verónica; Criollo, Alfredo; Quiroga, Clara; Olea-Azar, Claudio; Santibañez, Juan Francisco; Troncoso, Rodrigo; Chiong, Mario; Díaz-Araya, Guillermo; Foncea, Rocío; Lavandero, Sergio

    2006-08-07

    We have recently shown that hyperosmotic stress activates p65/RelB NFkappaB in cultured cardiomyocytes with dichotomic actions on caspase activation and cell death. It remains unexplored how NFkappaB is regulated in cultured rat cardiomyocytes exposed to hyperosmotic stress. We study here: (a) if hyperosmotic stress triggers reactive oxygen species (ROS) generation and in turn whether they regulate NFkappaB and (b) if insulin-like growth factor-1 (IGF-1) modulates ROS production and NFkappaB activation in hyperosmotically-stressed cardiomyocytes. The results showed that hyperosmotic stress generated ROS in cultured cardiac myocytes, in particular the hydroxyl and superoxide species, which were inhibited by N-acetylcysteine (NAC). Hyperosmotic stress-induced NFkappaB activation as determined by IkappaBalpha degradation and NFkappaB DNA binding. NFkappaB activation and procaspase-3 and -9 fragmentation were prevented by NAC and IGF-1. However, this growth factor did not decrease ROS generation induced by hyperosmotic stress, suggesting that its actions over NFkappaB and caspase activation may be due to modulation of events downstream of ROS generation. We conclude that hyperosmotic stress induces ROS, which in turn activates NFkappaB and caspases. IGF-1 prevents NFkappaB activation by a ROS-independent mechanism.

  2. Global transcriptomic analysis of induced cardiomyocytes predicts novel regulators for direct cardiac reprogramming.

    PubMed

    Talkhabi, Mahmood; Razavi, Seyed Morteza; Salari, Ali

    2017-04-04

    Heart diseases are the most significant cause of morbidity and mortality in the world. De novo generated cardiomyocytes (CMs) are a great cellular source for cell-based therapy and other potential applications. Direct cardiac reprogramming is the newest method to produce CMs, known as induced cardiomyocytes (iCMs). During a direct cardiac reprogramming, also known as transdifferentiation, non-cardiac differentiated adult cells are reprogrammed to cardiac identity by forced expression of cardiac-specific transcription factors (TFs) or microRNAs. To this end, many different combinations of TFs (±microRNAs) have been reported for direct reprogramming of mouse or human fibroblasts to iCMs, although their efficiencies remain very low. It seems that the investigated TFs and microRNAs are not sufficient for efficient direct cardiac reprogramming and other cardiac specific factors may be required for increasing iCM production efficiency, as well as the quality of iCMs. Here, we analyzed gene expression data of cardiac fibroblast (CFs), iCMs and adult cardiomyocytes (aCMs). The up-regulated and down-regulated genes in CMs (aCMs and iCMs) were determined as CM and CF specific genes, respectively. Among CM specific genes, we found 153 transcriptional activators including some cardiac and non-cardiac TFs that potentially activate the expression of CM specific genes. We also identified that 85 protein kinases such as protein kinase D1 (PKD1), protein kinase A (PRKA), calcium/calmodulin-dependent protein kinase (CAMK), protein kinase C (PRKC), and insulin like growth factor 1 receptor (IGF1R) that are strongly involved in establishing CM identity. CM gene regulatory network constructed using protein kinases, transcriptional activators and intermediate proteins predicted some new transcriptional activators such as myocyte enhancer factor 2A (MEF2A) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A), which may be required for qualitatively and

  3. Focal Adhesion Kinase-mediated Phosphorylation of Beclin1 Protein Suppresses Cardiomyocyte Autophagy and Initiates Hypertrophic Growth*♦

    PubMed Central

    Cheng, Zhaokang; Zhu, Qiang; Dee, Rachel; Opheim, Zachary; Mack, Christopher P.; Cyr, Douglas M.; Taylor, Joan M.

    2017-01-01

    Autophagy is an evolutionarily conserved intracellular degradation/recycling system that is essential for cellular homeostasis but is dysregulated in a number of diseases, including myocardial hypertrophy. Although it is clear that limiting or accelerating autophagic flux can result in pathological cardiac remodeling, the physiological signaling pathways that fine-tune cardiac autophagy are poorly understood. Herein, we demonstrated that stimulation of cardiomyocytes with phenylephrine (PE), a well known hypertrophic agonist, suppresses autophagy and that activation of focal adhesion kinase (FAK) is necessary for PE-stimulated autophagy suppression and subsequent initiation of hypertrophic growth. Mechanistically, we showed that FAK phosphorylates Beclin1, a core autophagy protein, on Tyr-233 and that this post-translational modification limits Beclin1 association with Atg14L and reduces Beclin1-dependent autophagosome formation. Remarkably, although ectopic expression of wild-type Beclin1 promoted cardiomyocyte atrophy, expression of a Y233E phosphomimetic variant of Beclin1 failed to affect cardiomyocyte size. Moreover, genetic depletion of Beclin1 attenuated PE-mediated/FAK-dependent initiation of myocyte hypertrophy in vivo. Collectively, these findings identify FAK as a novel negative regulator of Beclin1-mediated autophagy and indicate that this pathway can facilitate the promotion of compensatory hypertrophic growth. This novel mechanism to limit Beclin1 activity has important implications for treating a variety of pathologies associated with altered autophagic flux. PMID:27994061

  4. 14-3-3ε Plays a Role in Cardiac Ventricular Compaction by Regulating the Cardiomyocyte Cell Cycle

    PubMed Central

    Kosaka, Yasuhiro; Cieslik, Katarzyna A.; Li, Ling; Lezin, George; Maguire, Colin T.; Saijoh, Yukio; Toyo-oka, Kazuhito; Gambello, Michael J.; Vatta, Matteo; Wynshaw-Boris, Anthony; Baldini, Antonio; Yost, H. Joseph

    2012-01-01

    Trabecular myocardium accounts for the majority of the ventricles during early cardiogenesis, but compact myocardium is the primary component at later developmental stages. Elucidation of the genes regulating compact myocardium development is essential to increase our understanding of left ventricular noncompaction (LVNC), a cardiomyopathy characterized by increased ratios of trabecular to compact myocardium. 14-3-3ε is an adapter protein expressed in the lateral plate mesoderm, but its in vivo cardiac functions remain to be defined. Here we show that 14-3-3ε is expressed in the developing mouse heart as well as in cardiomyocytes. 14-3-3ε deletion did not appear to induce compensation by other 14-3-3 isoforms but led to ventricular noncompaction, with features similar to LVNC, resulting from a selective reduction in compact myocardium thickness. Abnormal compaction derived from a 50% decrease in cardiac proliferation as a result of a reduced number of cardiomyocytes in G2/M and the accumulation of cardiomyocytes in the G0/G1 phase of the cell cycle. These defects originated from downregulation of cyclin E1 and upregulation of p27Kip1, possibly through both transcriptional and posttranslational mechanisms. Our work shows that 14-3-3ε regulates cardiogenesis and growth of the compact ventricular myocardium by modulating the cardiomyocyte cell cycle via both cyclin E1 and p27Kip1. These data are consistent with the long-held view that human LVNC may result from compaction arrest, and they implicate 14-3-3ε as a new candidate gene in congenital human cardiomyopathies. PMID:23071090

  5. NF-κB (p65) negatively regulates myocardin-induced cardiomyocyte hypertrophy through multiple mechanisms.

    PubMed

    Liao, Xing-Hua; Wang, Nan; Zhao, Dong-Wei; Zheng, De-Liang; Zheng, Li; Xing, Wen-Jing; Zhou, Hao; Cao, Dong-Sun; Zhang, Tong-Cun

    2014-12-01

    Myocardin is well known to play a key role in the development of cardiomyocyte hypertrophy. But the exact molecular mechanism regulating myocardin stability and transactivity to affect cardiomyocyte hypertrophy has not been studied clearly. We now report that NF-κB (p65) can inhibit myocardin-induced cardiomyocyte hypertrophy. Then we explore the molecular mechanism of this response. First, we show that p65 can functionally repress myocardin transcriptional activity and also reduce the protein expression of myocardin. Second, the function of myocardin can be regulated by epigenetic modifications. Myocardin sumoylation is known to transactivate cardiac genes, but whether p65 can inhibit SUMO modification of myocardin is still not clear. Our data show that p65 weakens myocardin transcriptional activity through attenuating SUMO modification of myocardin by SUMO1/PIAS1, thereby impairing myocardin-mediated cardiomyocyte hypertrophy. Furthermore, the expression of myocardin can be regulated by several microRNAs, which play important roles in the development and function of the heart and muscle. We next investigated potential role of miR-1 in cardiac hypotrophy. Our results show that p65 can upregulate the level of miR-1 and miR-1 can decrease protein expression of myocardin in cardiac myocytes. Notably, miR-1 expression is also controlled by myocardin, leading to a feedback loop. These data thus provide important and novel insights into the function that p65 inhibits myocardin-mediated cardiomyocyte hypertrophy by downregulating the expression and SUMO modification of myocardin and enhancing the expression of miR-1.

  6. Reciprocal regulation of transcription factors and PLC isozyme gene expression in adult cardiomyocytes.

    PubMed

    Singal, Tushi; Dhalla, Naranjan S; Tappia, Paramjit S

    2010-06-01

    By employing a pharmacological approach, we have shown that phospholipase C (PLC) activity is involved in the regulation of gene expression of transcription factors such as c-Fos and c-Jun in cardiomyocytes in response to norepinephrine (NE). However, there is no information available regarding the identity of specific PLC isozymes involved in the regulation of c-Fos and c-Jun or on the involvement of these transcription factors in PLC isozyme gene expression in adult cardiomyocytes. In this study, transfection of cardiomyocytes with PLC isozyme specific siRNA was found to prevent the NE-mediated increases in the corresponding PLC isozyme gene expression, protein content and activity. Unlike PLC gamma(1) gene, silencing of PLC beta(1), beta(3) and delta(1) genes with si RNA prevented the increases in c-Fos and c-Jun gene expression in response to NE. On the other hand, transfection with c-Jun si RNA suppressed the NE-induced increase in c-Jun as well as PLC beta(1), beta(3) and delta(1) gene expression, but had no effect on PLC gamma(1) gene expression. Although transfection of cardiomyocytes with c-Fos si RNA prevented NE-induced expression of c-Fos, PLC beta(1) and PLC beta(3) genes, it did not affect the increases in PLC delta(1) and PLC gamma(1) gene expression. Silencing of either c-Fos or c-Jun also depressed the NE-mediated increases in PLC beta(1), beta(3) and gamma(1) protein content and activity in an isozyme specific manner. Furthermore, silencing of all PLC isozymes as well as of c-Fos and c-Jun resulted in prevention of the NE-mediated increase in atrial natriuretic factor gene expression. These findings, by employing gene silencing techniques, demonstrate that there occurs a reciprocal regulation of transcription factors and specific PLC isozyme gene expression in cardiomyocytes.

  7. Myofibrillogenesis regulator 1 induces hypertrophy by promoting sarcomere organization in neonatal rat cardiomyocytes.

    PubMed

    Wang, Xiaoreng; Liu, Xiuhua; Wang, Song; Luan, Kang

    2012-06-01

    Human myofibrillogenesis regulator 1, a novel 17-kDa protein, is closely involved in cardiac hypertrophy. We studied the molecular mechanism that links MR-1 to hypertrophic response. Hypertrophic hallmarks such as cell size and [(3)H]-leucine incorporation were significantly increased when MR-1 was transfected into cardiomyocytes for 48 h. However, sarcomere organization was promoted when MR-1 was transfected for 8 h. The finding that cardiac hypertrophy was induced long after increase of sarcomere organization indicates that the promoted sarcomere organization may be one of the crucial factors causing hypertrophy. Furthermore, when MR-1 was transfected into cardiomyocytes, the nuclear localization of myomesin-1 was shifted to the cytoplasm. Transfection with small ubiquitin-like modifier-1 (SUMO-1) mimicked the effect of MR-1 inducing translocation of myomesin-1. However, transfection with SUMO-1 in MR-1-silenced cardiomyocytes failed to induce translocation and sarcomere organization, even though SUMO-1 expression was at the same level. Overexpression of MR-1 may induce cardiomyocyte hypertrophy via myomesin-1-mediated sarcomere organization.

  8. Myofibrillogenesis regulator 1 induces hypertrophy by promoting sarcomere organization in neonatal rat cardiomyocytes

    PubMed Central

    Wang, Xiaoreng; Liu, Xiuhua; Wang, Song; Luan, Kang

    2012-01-01

    Human myofibrillogenesis regulator 1, a novel 17-kDa protein, is closely involved in cardiac hypertrophy. We studied the molecular mechanism that links MR-1 to hypertrophic response. Hypertrophic hallmarks such as cell size and [3H]-leucine incorporation were significantly increased when MR-1 was transfected into cardiomyocytes for 48 h. However, sarcomere organization was promoted when MR-1 was transfected for 8 h. The finding that cardiac hypertrophy was induced long after increase of sarcomere organization indicates that the promoted sarcomere organization may be one of the crucial factors causing hypertrophy. Furthermore, when MR-1 was transfected into cardiomyocytes, the nuclear localization of myomesin-1 was shifted to the cytoplasm. Transfection with small ubiquitin-like modifier-1 (SUMO-1) mimicked the effect of MR-1 inducing translocation of myomesin-1. However, transfection with SUMO-1 in MR-1-silenced cardiomyocytes failed to induce translocation and sarcomere organization, even though SUMO-1 expression was at the same level. Overexpression of MR-1 may induce cardiomyocyte hypertrophy via myomesin-1-mediated sarcomere organization. PMID:22418241

  9. Fibroblast growth factor receptor-1 is essential for in vitro cardiomyocyte development.

    PubMed

    Dell'Era, Patrizia; Ronca, Roberto; Coco, Laura; Nicoli, Stefania; Metra, Marco; Presta, Marco

    2003-09-05

    Fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling plays a crucial role in mesoderm formation and patterning. Heartless mutant studies in Drosophila suggest that FGFR1, among the different FGFRs, may play a role in cardiogenesis. However, fgfr1-/- mice die during gastrulation before heart formation. To establish the contribution of FGFR1 in cardiac development, we investigated the capacity of murine fgfr1+/- and fgfr1-/- embryonic stem (ES) cells to differentiate to cardiomyocytes in vitro. Clusters of pulsating cardiomyocytes were observed in >90% of 3-dimensional embryoid bodies (EBs) originated from fgfr1+/- ES cells at day 9 to 10 of differentiation. In contrast, 10% or less of fgfr1-/- EBs showed beating foci at day 16. Accordingly, fgfr1-/- EBs were characterized by impaired expression of early cardiac transcription factors Nkx2.5 and d-Hand and of late structural cardiac genes myosin heavy chain (MHC)-alpha, MHC-beta, and ventricular myosin light chain. Homozygous fgfr1 mutation resulted also in alterations of the expression of mesoderm-related early genes, including nodal, BMP2, BMP4, T(bra), and sonic hedgehog. Nevertheless, fgfr1+/- and fgfr1-/- EBs similarly express cardiogenic precursor, endothelial, hematopoietic, and skeletal muscle markers, indicating that fgfr1-null mutation exerts a selective effect on cardiomyocyte development in differentiating ES cells. Accordingly, inhibitors of FGFR signaling, including the FGFR1 tyrosine kinase inhibitor SU 5402, the MEK1/2 inhibitor U0126, and the protein kinase C inhibitor GF109 all prevented cardiomyocyte differentiation in fgfr1+/- EBs without affecting the expression of the hematopoietic/endothelial marker flk-1. In conclusion, the data point to a nonredundant role for FGFR1-mediated signaling in cardiomyocyte development.

  10. Adenosine monophosphate-activated protein kinase attenuates cardiomyocyte hypertrophy through regulation of FOXO3a/MAFbx signaling pathway.

    PubMed

    Chen, Baolin; Wu, Qiang; Xiong, Zhaojun; Ma, Yuedong; Yu, Sha; Chen, Dandan; Huang, Shengwen; Dong, Yugang

    2016-09-01

    Control of cardiac muscle mass is thought to be determined by a dynamic balance of protein synthesis and degradation. Recent studies have demonstrated that atrophy-related forkhead box O 3a (FOXO3a)/muscle atrophy F-box (MAFbx) signaling pathway plays a central role in the modulation of proteolysis and exert inhibitory effect on cardiomyocyte hypertrophy. In this study, we tested the hypothesis that adenosine monophosphate-activated protein kinase (AMPK) activation attenuates cardiomyocyte hypertrophy by regulating FOXO3a/MAFbx signaling pathway and its downstream protein degradation. The results showed that activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) attenuated cardiomyocyte hypertrophy induced by angiotensin II (Ang II). The antihypertrophic effects of AICAR were blunted by AMPK inhibitor Compound C. In addition, AMPK dramatically increased the activity of transcription factor FOXO3a, up-regulated the expression of its downstream ubiquitin ligase MAFbx, and enhanced cardiomyocyte proteolysis. Meanwhile, the effects of AMPK on protein degradation and cardiomyocyte hypertrophy were blocked after MAFbx was silenced by transfection of cardiomyocytes with MAFbx-siRNA. These results indicate that AMPK plays an important role in the inhibition of cardiomyocyte hypertrophy by activating protein degradation via FOXO3a/MAFbx signaling pathway.

  11. Mitofusin 1 Is Negatively Regulated by MicroRNA 140 in Cardiomyocyte Apoptosis

    PubMed Central

    Li, Jincheng; Li, Yuzhen; Jiao, Jianqin; Wang, Jianxun; Li, Yanrui

    2014-01-01

    MicroRNAs (miRNAs) are a class of small noncoding RNAs that mediate posttranscriptional gene silencing. Mitochondrial fission participates in the induction of apoptosis. It remains largely unknown whether miRNAs can regulate mitochondrial fission. Reactive oxygen species and doxorubicin could induce mitochondrial fission and apoptosis in cardiomyocytes. Concomitantly, mitofusin 1 (Mfn1) was downregulated, whereas miRNA 140 (miR-140) was upregulated upon apoptotic stimulation. We investigated whether Mfn1 and miR-140 play a functional role in mitochondrial fission and apoptosis. Ectopic expression of Mfn1 attenuated mitochondrial fission and apoptosis. Knockdown of miR-140 inhibited mitochondrial fission. Our results further revealed that knockdown of miR-140 was able to reduce myocardial infarct sizes in an animal model. We observed that miR-140 could suppress the expression of Mfn1, and it exerted its effect on mitochondrial fission and apoptosis through targeting Mfn1. Our data revealed that mitochondrial fission occurs in cardiomyocytes and can be counteracted by Mfn1. However, the function of Mfn1 is negatively regulated by miR-140. Our present work suggests that Mfn1 and miR-140 are integrated into the program of cardiomyocyte apoptosis. PMID:24615014

  12. Cyclic stretch of Embryonic Cardiomyocytes Increases Proliferation, Growth, and Expression While Repressing Tgf-β Signaling

    PubMed Central

    Banerjee, Indroneal; Carrion, Katrina; Serrano, Ricardo; Dyo, Jeffrey; Sasik, Roman; Lund, Sean; Willems, Erik; Aceves, Seema; Meili, Rudolph; Mercola, Mark; Chen, Ju; Zambon, Alexander; Hardiman, Gary; Doherty, Taylor A; Lange, Stephan; del Álamo, Juan C.; Nigam, Vishal

    2014-01-01

    Perturbed biomechanical stimuli are thought to be critical for the pathogenesis of a number of congenital heart defects, including Hypoplastic Left Heart Syndrome (HLHS). While embryonic cardiomyocytes experience biomechanical stretch every heart beat, their molecular responses to biomechanical stimuli during heart development are poorly understood. We hypothesized that biomechanical stimuli activate specific signaling pathways that impact proliferation, gene expression and myocyte contraction. The objective of this study was to expose embryonic mouse cardiomyocytes (EMCM) to cyclic stretch and examine key molecular and phenotypic responses. Analysis of RNA-Sequencing data demonstrated that gene ontology groups associated with myofibril and cardiac development were significantly modulated. Stretch increased EMCM proliferation, size, cardiac gene expression, and myofibril protein levels. Stretch also repressed several components belonging to the Transforming Growth Factor-β (Tgf-β) signaling pathway. EMCMs undergoing cyclic stretch had decreased Tgf-β expression, protein levels, and signaling. Furthermore, treatment of EMCMs with a Tgf-β inhibitor resulted in increased EMCM size. Functionally, Tgf-β signaling repressed EMCM proliferation and contractile function, as assayed via dynamic monolayer force microscopy (DMFM). Taken together, these data support the hypothesis that biomechanical stimuli play a vital role in normal cardiac development and for cardiac pathology, including HLHS. PMID:25446186

  13. Plant Growth Regulators.

    ERIC Educational Resources Information Center

    Nickell, Louis G.

    1978-01-01

    Describes the effect of "plant growth regulators" on plants, such as controlling the flowering, fruit development, plant size, and increasing crop yields. Provides a list of plant growth regulators which includes their chemical, common, and trade names, as well as their different use(s). (GA)

  14. [The influence of fibroblast growth factor (FGF2) on cardiomyocytes differentiation of mesenchymal stem cells of bone marrow ex vivo].

    PubMed

    Lobanok, E S; Kvacheva, Z B; Pinchuk, S V; Volk, M V; Mezhevkina, L M; Fesenko, E E; Volotovski, I D

    2014-01-01

    The influence of FGF2 on the efficiency of cardiomyocytes differentiation of mesenchymal stem cells (MSC) of bone marrow induced by 5-azacetidine (5-aza) was studied. The effect of FGF2 developing by the 14th day after the combined action of a differentiating agent and growth factor was manifested in an increase in Mef2A, Mef2D and gene transcription and a rise of ionized Ca2+ concentration in cytoplasm keeping cell viability and proliferation activity. In the presence of FGF2 this approach provided cardiomyogenesis and the increase in the formation of early precursors of cardiomyocytes.

  15. FOG-2 mediated recruitment of the NuRD complex regulates cardiomyocyte proliferation during heart development.

    PubMed

    Garnatz, Audrey S; Gao, Zhiguang; Broman, Michael; Martens, Spencer; Earley, Judy U; Svensson, Eric C

    2014-11-01

    FOG-2 is a multi-zinc finger protein that binds the transcriptional activator GATA4 and modulates GATA4-mediated regulation of target genes during heart development. Our previous work has demonstrated that the Nucleosome Remodeling and Deacetylase (NuRD) complex physically interacts with FOG-2 and is necessary for FOG-2 mediated repression of GATA4 activity in vitro. However, the relevance of this interaction for FOG-2 function in vivo has remained unclear. In this report, we demonstrate the importance of FOG-2/NuRD interaction through the generation and characterization of mice homozygous for a mutation in FOG-2 that disrupts NuRD binding (FOG-2(R3K5A)). These mice exhibit a perinatal lethality and have multiple cardiac malformations, including ventricular and atrial septal defects and a thin ventricular myocardium. To investigate the etiology of the thin myocardium, we measured the rate of cardiomyocyte proliferation in wild-type and FOG-2(R3K5A) developing hearts. We found cardiomyocyte proliferation was reduced by 31±8% in FOG-2(R3K5A) mice. Gene expression analysis indicated that the cell cycle inhibitor Cdkn1a (p21(cip1)) is up-regulated 2.0±0.2-fold in FOG-2(R3K5A) hearts. In addition, we demonstrate that FOG-2 can directly repress the activity of the Cdkn1a gene promoter, suggesting a model by which FOG-2/NuRD promotes ventricular wall thickening by repression of this cell cycle inhibitor. Consistent with this notion, the genetic ablation of Cdkn1a in FOG-2(R3K5A) mice leads to an improvement in left ventricular function and a partial rescue of left ventricular wall thickness. Taken together, our results define a novel mechanism in which FOG-2/NuRD interaction is required for cardiomyocyte proliferation by directly down-regulating the cell cycle inhibitor Cdkn1a during heart development.

  16. Platelet-derived growth factor (PDGF) signaling directs cardiomyocyte movement toward the midline during heart tube assembly.

    PubMed

    Bloomekatz, Joshua; Singh, Reena; Prall, Owen Wj; Dunn, Ariel C; Vaughan, Megan; Loo, Chin-San; Harvey, Richard P; Yelon, Deborah

    2017-01-18

    Communication between neighboring tissues plays a central role in guiding organ morphogenesis. During heart tube assembly, interactions with the adjacent endoderm control the medial movement of cardiomyocytes, a process referred to as cardiac fusion. However, the molecular underpinnings of this endodermal-myocardial relationship remain unclear. Here, we show an essential role for platelet-derived growth factor receptor alpha (Pdgfra) in directing cardiac fusion. Mutation of pdgfra disrupts heart tube assembly in both zebrafish and mouse. Timelapse analysis of individual cardiomyocyte trajectories reveals misdirected cells in zebrafish pdgfra mutants, suggesting that PDGF signaling steers cardiomyocytes toward the midline during cardiac fusion. Intriguingly, the ligand pdgfaa is expressed in the endoderm medial to the pdgfra-expressing myocardial precursors. Ectopic expression of pdgfaa interferes with cardiac fusion, consistent with an instructive role for PDGF signaling. Together, these data uncover a novel mechanism through which endodermal-myocardial communication can guide the cell movements that initiate cardiac morphogenesis.

  17. Sildenafil prevents the up-regulation of transient receptor potential canonical channels in the development of cardiomyocyte hypertrophy

    SciTech Connect

    Kiso, Hironori; Ohba, Takayoshi; Iino, Kenji; Sato, Kazuhiro; Terata, Yutaka; Murakami, Manabu; Ono, Kyoichi; Watanabe, Hiroyuki; Ito, Hiroshi

    2013-07-05

    Highlights: •Transient receptor potential canonical (TRPC1, 3 and 6) are up-regulated by ET-1. •Sildenafil inhibited hypertrophic responses (BNP, Ca entry, NFAT activation). •Sildenafil suppressed TRPC1, 3 and 6 expression. -- Abstract: Background: Transient receptor potential canonical (TRPCs) channels are up-regulated in the development of cardiac hypertrophy. Sildenafil inhibits TRPC6 activation and expression, leading to the prevention of cardiac hypertrophy. However, the effects of sildenafil on the expression of other TRPCs remain unknown. We hypothesized that in addition to its effects of TRPC6, sildenafil blocks the up-regulation of other TRPC channels to suppress cardiomyocyte hypertrophy. Methods and results: In cultured neonatal rat cardiomyocytes, a 48 h treatment with 10 nM endothelin (ET)-1 induced hypertrophic responses characterized by nuclear factor of activated T cells activation and enhancement of brain natriuretic peptide expression and cell surface area. Co-treatment with sildenafil (1 μM, 48 h) inhibited these ET-1-induced hypertrophic responses. Although ET-1 enhanced the gene expression of TRPCs, sildenafil inhibited the enhanced gene expression of TRPC1, C3 and C6. Moreover, co-treatment with sildenafil abolished the augmentation of SOCE in the hypertrophied cardiomyocytes. Conclusions: These results suggest that sildenafil inhibits cardiomyocyte hypertrophy by suppressing the up-regulation of TRPC expression.

  18. Autoantibodies in dilated cardiomyopathy induce vascular endothelial growth factor expression in cardiomyocytes

    SciTech Connect

    Saygili, Erol; Noor-Ebad, Fawad; Schröder, Jörg W.; Mischke, Karl; Saygili, Esra; Rackauskas, Gediminas; Marx, Nikolaus; Kelm, Malte; Rana, Obaida R.

    2015-09-11

    Background: Autoantibodies have been identified as major predisposing factors for dilated cardiomyopathy (DCM). Patients with DCM show elevated serum levels of vascular endothelial growth factor (VEGF) whose source is unknown. Besides its well-investigated effects on angiogenesis, evidence is present that VEGF signaling is additionally involved in fibroblast proliferation and cardiomyocyte hypertrophy, hence in cardiac remodeling. Whether autoimmune effects in DCM impact cardiac VEGF signaling needs to be elucidated. Methods: Five DCM patients were treated by the immunoadsorption (IA) therapy on five consecutive days. The eluents from the IA columns were collected and prepared for cell culture. Cardiomyocytes from neonatal rats (NRCM) were incubated with increasing DCM-immunoglobulin-G (IgG) concentrations for 48 h. Polyclonal IgG (Venimmun N), which was used to restore IgG plasma levels in DCM patients after the IA therapy was additionally used for control cell culture purposes. Results: Elevated serum levels of VEGF decreased significantly after IA (Serum VEGF (ng/ml); DCM pre-IA: 45 ± 9.1 vs. DCM post–IA: 29 ± 6.7; P < 0.05). In cell culture, pretreatment of NRCM by DCM-IgG induced VEGF expression in a time and dose dependent manner. Biologically active VEGF that was secreted by NRCM significantly increased BNP mRNA levels in control cardiomyocytes and induced cell-proliferation of cultured cardiac fibroblast (Fibroblast proliferation; NRCM medium/HC-IgG: 1 ± 0.0 vs. NRCM medium/DCM-IgG 100 ng/ml: 5.6 ± 0.9; P < 0.05). Conclusion: The present study extends the knowledge about the possible link between autoimmune signaling in DCM and VEGF induction. Whether this observation plays a considerable role in cardiac remodeling during DCM development needs to be further elucidated. - Highlights: • Mechanisms of remodeling in dilated cardiomyopathy (DCM) are not fully understood. • Autoantibodies have been identified as major predisposing factors

  19. Stk38 Modulates Rbm24 Protein Stability to Regulate Sarcomere Assembly in Cardiomyocytes

    PubMed Central

    Liu, Jing; Kong, Xu; Yew Mun, Lee; Meng Kai, Zhang; Li Yan, Guo; Lin, Yu; Lim, Teck Kwang; Lin, Qingsong; Xu, Xiu Qin

    2017-01-01

    RNA-binding protein Rbm24 is a key regulator of heart development and required for sarcomere assembly and heart contractility. Yet, its underlying mechanism remains unclear. Here, we link serine/threonine kinase 38 (Stk38) signaling to the regulation of Rbm24 by showing that Rbm24 phosphorylation and its function could be modulated by Stk38. Using co-immunoprecipitation coupled with mass spectrometry technique, we identified Stk38 as an endogenous binding partner of Rbm24. Stk38 knockdown resulted in decreased Rbm24 protein level in cardiomyocytes. Further studies using Stk38 kinase inhibitor or activator showed that Rbm24 protein stability was regulated in a kinase activity-dependent manner. Deficiency of Stk38 caused reduction of sarcomere proteins and disarrangement of sarcomere, suggesting that Stk38 is essential for Rbm24 to regulate sarcomere assembly. Our results revealed that Stk38 kinase catalyzes the phosphorylation of Rbm24 during sarcomerogensis and this orchestrates accurate sarcomere alignment. This furthers our understanding of the regulatory mechanism of cardiac sarcomere assembly in both physiologic and pathologic contexts, and uncovers a potential novel pathway to cardiomyopathy through modulating the Stk38/Rbm24 protein activity. PMID:28322254

  20. Tbx20 Is an Essential Regulator of Embryonic Heart Growth in Zebrafish

    PubMed Central

    Berger, Ina M.; Bühler, Anja; Keßler, Mirjam; Rottbauer, Wolfgang

    2016-01-01

    The molecular mechanisms that regulate cardiomyocyte proliferation during embryonic heart growth are not completely deciphered yet. In a forward genetic N-ethyl-N-nitrosourea (ENU) mutagenesis screen, we identified the recessive embryonic-lethal zebrafish mutant line weiches herz (whz). Homozygous mutant whz embryos display impaired heart growth due to diminished embryonic cardiomyocyte proliferation resulting in cardiac hypoplasia and weak cardiac contraction. By positional cloning, we found in whz mutant zebrafish a missense mutation within the T-box 20 (Tbx20) transcription factor gene leading to destabilization of Tbx20 protein. Morpholino-mediated knock-down of Tbx20 in wild-type zebrafish embryos phenocopies whz, indicating that the whz phenotype is due to loss of Tbx20 function, thereby leading to significantly reduced cardiomyocyte numbers by impaired proliferation of heart muscle cells. Ectopic overexpression of wild-type Tbx20 in whz mutant embryos restored cardiomyocyte proliferation and heart growth. Interestingly, ectopic overexpression of Tbx20 in wild-type zebrafish embryos resulted, similar to the situation in the embryonic mouse heart, in significantly reduced proliferation rates of ventricular cardiomyocytes, suggesting that Tbx20 activity needs to be tightly fine-tuned to guarantee regular cardiomyocyte proliferation and embryonic heart growth in vivo. PMID:27907103

  1. Tetrahydrobiopterin Protects against Radiation-induced Growth Inhibition in H9c2 Cardiomyocytes

    PubMed Central

    Zhang, Zheng-Yi; Li, Yi; Li, Rui; Zhang, An-An; Shang, Bo; Yu, Jing; Xie, Xiao-Dong

    2016-01-01

    Background: Tetrahydrobiopterin (BH4) is an essential cofactor of nitric oxide synthases (NOSs) for the synthesis of nitric oxide (NO). BH4 therapy can reverse the disease-related redox disequilibrium observed with BH4 deficiency. However, whether BH4 exerts a protective effect against radiation-induced damage to cardiomyocytes remains unknown. Methods: Clonogenic assays were performed to determine the effects of X-ray on H9c2 cells with or without BH4 treatment. The contents of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA) in H9c2 cells were measured to investigate oxidative stress levels. The cell cycle undergoing radiation with or without BH4 treatment was detected using flow cytometry. The expression levels of proteins in the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT)/P53 signaling pathway, inducible NOS (iNOS), and endothelial NOS (eNOS) were examined using Western blotting. Results: X-ray radiation significantly inhibited the growth of H9c2 cells in a dose-dependent manner, whereas BH4 treatment significantly reduced the X-ray radiation-induced growth inhibition (control group vs. X-ray groups, respectively, P < 0.01). X-ray radiation induced LDH release, apoptosis, and G0/G1 peak accumulation, significantly increasing the level of MDA and the production of NO, and decreased the level of SOD (control group vs. X-ray groups, respectively, P < 0.05 or P < 0.01). By contrast, BH4 treatment can significantly reverse these processes (BH4 treatment groups vs. X-ray groups, P < 0.05 or P < 0.01). BH4 reversed the X-ray radiation-induced expression alterations of apoptosis-related molecules, including B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein, and caspase-3, and molecules of the PI3K/Akt/P53 signaling pathway. BH4 enhanced the production of NO in 2 Gy and 4 Gy radiated groups by upregulating eNOS protein expression and downregulating iNOS protein expression. Conclusions: BH4 treatment can protect

  2. Dynamic DNA methylation orchestrates cardiomyocyte development, maturation and disease

    PubMed Central

    Gilsbach, Ralf; Preissl, Sebastian; Grüning, Björn A.; Schnick, Tilman; Burger, Lukas; Benes, Vladimir; Würch, Andreas; Bönisch, Ulrike; Günther, Stefan; Backofen, Rolf; Fleischmann, Bernd K.; Schübeler, Dirk; Hein, Lutz

    2014-01-01

    The heart is a highly specialized organ with essential function for the organism throughout life. The significance of DNA methylation in shaping the phenotype of the heart remains only partially known. Here we generate and analyse DNA methylomes from highly purified cardiomyocytes of neonatal, adult healthy and adult failing hearts. We identify large genomic regions that are differentially methylated during cardiomyocyte development and maturation. Demethylation of cardiomyocyte gene bodies correlates strongly with increased gene expression. Silencing of demethylated genes is characterized by the polycomb mark H3K27me3 or by DNA methylation. De novo methylation by DNA methyltransferases 3A/B causes repression of fetal cardiac genes, including essential components of the cardiac sarcomere. Failing cardiomyocytes partially resemble neonatal methylation patterns. This study establishes DNA methylation as a highly dynamic process during postnatal growth of cardiomyocytes and their adaptation to pathological stress in a process tightly linked to gene regulation and activity. PMID:25335909

  3. Dynamic DNA methylation orchestrates cardiomyocyte development, maturation and disease.

    PubMed

    Gilsbach, Ralf; Preissl, Sebastian; Grüning, Björn A; Schnick, Tilman; Burger, Lukas; Benes, Vladimir; Würch, Andreas; Bönisch, Ulrike; Günther, Stefan; Backofen, Rolf; Fleischmann, Bernd K; Schübeler, Dirk; Hein, Lutz

    2014-10-22

    The heart is a highly specialized organ with essential function for the organism throughout life. The significance of DNA methylation in shaping the phenotype of the heart remains only partially known. Here we generate and analyse DNA methylomes from highly purified cardiomyocytes of neonatal, adult healthy and adult failing hearts. We identify large genomic regions that are differentially methylated during cardiomyocyte development and maturation. Demethylation of cardiomyocyte gene bodies correlates strongly with increased gene expression. Silencing of demethylated genes is characterized by the polycomb mark H3K27me3 or by DNA methylation. De novo methylation by DNA methyltransferases 3A/B causes repression of fetal cardiac genes, including essential components of the cardiac sarcomere. Failing cardiomyocytes partially resemble neonatal methylation patterns. This study establishes DNA methylation as a highly dynamic process during postnatal growth of cardiomyocytes and their adaptation to pathological stress in a process tightly linked to gene regulation and activity.

  4. Identification of genes directly regulated by the intrinsic circadian clock within the cardiomyocyte

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Circadian rhythms in cardiovascular physiology (e.g., heart rate, cardiac output) and pathophysiology (e.g., arrhythmias) are firmly established. These phenomena have been attributed primarily to circadian rhythms in neurohumoral influences (e.g., sympathetic activity). Nevertheless, cardiomyocytes ...

  5. 5-Azacytidine delivered by mesoporous silica nanoparticles regulates the differentiation of P19 cells into cardiomyocytes

    NASA Astrophysics Data System (ADS)

    Cheng, Jin; Ding, Qian; Wang, Jia; Deng, Lin; Yang, Lu; Tao, Lei; Lei, Haihong; Lu, Shaoping

    2016-01-01

    Heart disease is one of the deadliest diseases causing mortality due to the limited regenerative capability of highly differentiated cardiomyocytes. Stem cell-based therapy in tissue engineering is one of the most exciting and rapidly growing areas and raises promising prospects for cardiac repair. In this study, we have synthesized FITC-mesoporous silica nanoparticles (FMSNs) based on a sol-gel method (known as Stöber's method) as a drug delivery platform to transport 5-azacytidine in P19 embryonic carcinoma stem cells. The surfactant CTAB is utilized as a liquid crystal template to self-aggregate into micelles, resulting in the synthesis of MSNs. Based on the cell viability assay, treatment with FMSNs + 5-azacytidine resulted in much more significant inhibition of the proliferation than 5-azacytidine alone. To study the mechanism, we have tested the differentiation genes and cardiac marker genes in P19 cells and found that these genes have been up-regulated in P19 embryonic carcinoma stem cells treated with FMSNs + 5-azacytidine + poly(allylamine hydrochloride) (PAH), with the changes of histone modifications on the regulatory region. In conclusion, with FMSNs as drug delivery platforms, 5-azacytidine can be more efficiently delivered into stem cells and can be used to monitor and track the transfection process in situ to clarify their effects on stem cell functions and the differentiation process, which can serve as a promising tool in tissue engineering and other biomedical fields.

  6. Platelet-derived growth factor (PDGF) signaling directs cardiomyocyte movement toward the midline during heart tube assembly

    PubMed Central

    Bloomekatz, Joshua; Singh, Reena; Prall, Owen WJ; Dunn, Ariel C; Vaughan, Megan; Loo, Chin-San; Harvey, Richard P; Yelon, Deborah

    2017-01-01

    Communication between neighboring tissues plays a central role in guiding organ morphogenesis. During heart tube assembly, interactions with the adjacent endoderm control the medial movement of cardiomyocytes, a process referred to as cardiac fusion. However, the molecular underpinnings of this endodermal-myocardial relationship remain unclear. Here, we show an essential role for platelet-derived growth factor receptor alpha (Pdgfra) in directing cardiac fusion. Mutation of pdgfra disrupts heart tube assembly in both zebrafish and mouse. Timelapse analysis of individual cardiomyocyte trajectories reveals misdirected cells in zebrafish pdgfra mutants, suggesting that PDGF signaling steers cardiomyocytes toward the midline during cardiac fusion. Intriguingly, the ligand pdgfaa is expressed in the endoderm medial to the pdgfra-expressing myocardial precursors. Ectopic expression of pdgfaa interferes with cardiac fusion, consistent with an instructive role for PDGF signaling. Together, these data uncover a novel mechanism through which endodermal-myocardial communication can guide the cell movements that initiate cardiac morphogenesis. DOI: http://dx.doi.org/10.7554/eLife.21172.001 PMID:28098558

  7. Cucurbitacin I Attenuates Cardiomyocyte Hypertrophy via Inhibition of Connective Tissue Growth Factor (CCN2) and TGF- β/Smads Signalings

    PubMed Central

    Kang, Hara; Park, Kye Won; Park, Woo Jin; Yang, Seung Yul; Yang, Dong Kwon

    2015-01-01

    Cucurbitacin I is a naturally occurring triterpenoid derived from Cucurbitaceae family plants that exhibits a number of potentially useful pharmacological and biological activities. However, the therapeutic impact of cucurbitacin I on the heart has not heretofore been reported. To evaluate the functional role of cucurbitacin I in an in vitro model of cardiac hypertrophy, phenylephrine (PE)-stimulated cardiomyocytes were treated with a sub-cytotoxic concentration of the compound, and the effects on cell size and mRNA expression levels of ANF and β-MHC were investigated. Consequently, PE-induced cell enlargement and upregulation of ANF and β-MHC were significantly suppressed by pretreatment of the cardiomyocytes with cucurbitacin I. Notably, cucurbitacin I also impaired connective tissue growth factor (CTGF) and MAPK signaling, pro-hypertrophic factors, as well as TGF-β/Smad signaling, the important contributing factors to fibrosis. The protective impact of cucurbitacin I was significantly blunted in CTGF-silenced or TGF-β1-silenced hypertrophic cardiomyocytes, indicating that the compound exerts its beneficial actions through CTGF. Taken together, these findings signify that cucurbitacin I protects the heart against cardiac hypertrophy via inhibition of CTGF/MAPK, and TGF- β/Smad-facilitated events. Accordingly, the present study provides new insights into the defensive capacity of cucurbitacin I against cardiac hypertrophy, and further suggesting cucurbitacin I’s utility as a novel therapeutic agent for the management of heart diseases. PMID:26296085

  8. Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.

    PubMed

    Weber, David; Heisig, Julia; Kneitz, Susanne; Wolf, Elmar; Eilers, Martin; Gessler, Manfred

    2015-02-01

    Hey bHLH transcription factors are critical effectors of Notch signaling. During mammalian heart development they are expressed in atrial and ventricular cardiomyocytes and in the developing endocardium. Hey knockout mice suffer from lethal cardiac defects, such as ventricular septum defects, valve defects and cardiomyopathy. Despite this functional relevance, little is known about the regulation of downstream targets in relevant cell types. The objective of this study was to elucidate the regulatory mechanisms by which Hey proteins affect gene expression in a cell type specific manner. We used an in vitro cardiomyocyte differentiation system with inducible Hey1 or Hey2 expression to study target gene regulation in cardiomyocytes (CM) generated from murine embryonic stem cells (ESC). The effects of Hey1 and Hey2 are largely redundant, but cell type specific. The number of regulated genes is comparable between ESC and CM, but the total number of binding sites is much higher, especially in ESC, targeting mainly genes involved in transcriptional regulation and developmental processes. Repression by Hey proteins generally correlates with the extent of Hey-binding to target promoters, Hdac recruitment and lower histone acetylation. Functionally, treatment with the Hdac inhibitor TSA abolished Hey target gene regulation. However, in CM the repressive effect of Hey-binding is lost for a subset of genes. These also lack Hey-dependent histone deacetylation in CM and are enriched for binding sites of cardiac specific activators like Srf, Nkx2-5, and Gata4. Ectopic Nkx2-5 overexpression in ESC blocks Hey-mediated repression of these genes. Thus, Hey proteins mechanistically repress target genes via Hdac recruitment and histone deacetylation. In CM Hey-repression is counteracted by cardiac activators, which recruit histone acetylases and prevent Hey mediated deacetylation and subsequent repression for a subset of genes.

  9. MicroRNA-30d regulates cardiomyocyte pyroptosis by directly targeting foxo3a in diabetic cardiomyopathy.

    PubMed

    Li, X; Du, N; Zhang, Q; Li, J; Chen, X; Liu, X; Hu, Y; Qin, W; Shen, N; Xu, C; Fang, Z; Wei, Y; Wang, R; Du, Z; Zhang, Y; Lu, Y

    2014-10-23

    Diabetic cardiomyopathy is a common cardiac condition in patients with diabetes mellitus, which can result in cardiac hypertrophy and subsequent heart failure, associated with pyroptosis, the pro-inflammatory programmed cell death. MicroRNAs (miRNAs), small endogenous non-coding RNAs, have been shown to be involved in diabetic cardiomyopathy. However, whether miRNAs regulate pyroptosis in diabetic cardiomyopathy remains unknown. Our study revealed that mir-30d expression was substantially increased in streptozotocin (STZ)-induced diabetic rats and in high-glucose-treated cardiomyocytes as well. Upregulation of mir-30d promoted cardiomyocyte pyroptosis in diabetic cardiomyopathy; conversely, knockdown of mir-30d attenuated it. In an effort to understand the signaling mechanisms underlying the pro-pyroptotic property of mir-30d, we found that forced expression of mir-30d upregulated caspase-1 and pro-inflammatory cytokines IL-1β and IL-18. Moreover, mir-30d directly repressed foxo3a expression and its downstream protein, apoptosis repressor with caspase recruitment domain (ARC). Furthermore, silencing ARC by siRNA mimicked the action of mir-30d: upregulating caspase-1 and inducing pyroptosis. These findings promoted us to propose a new signaling pathway leading to cardiomyocyte pyroptosis under hyperglycemic conditions: mir-30d↑→foxo3a↓→ ARC↓→caspase-1↑→IL-1β, IL-18↑→pyroptosis↑. Therefore, mir-30d may be a promising therapeutic target for the management of diabetic cardiomyopathy.

  10. Caveolin-3 regulates compartmentation of cardiomyocyte beta2-adrenergic receptor-mediated cAMP signaling.

    PubMed

    Wright, Peter T; Nikolaev, Viacheslav O; O'Hara, Thomas; Diakonov, Ivan; Bhargava, Anamika; Tokar, Sergiy; Schobesberger, Sophie; Shevchuk, Andrew I; Sikkel, Markus B; Wilkinson, Ross; Trayanova, Natalia A; Lyon, Alexander R; Harding, Sian E; Gorelik, Julia

    2014-02-01

    The purpose of this study was to investigate whether caveolin-3 (Cav3) regulates localization of β2-adrenergic receptor (β2AR) and its cAMP signaling in healthy or failing cardiomyocytes. We co-expressed wildtype Cav3 or its dominant-negative mutant (Cav3DN) together with the Förster resonance energy transfer (FRET)-based cAMP sensor Epac2-camps in adult rat ventricular myocytes (ARVMs). FRET and scanning ion conductance microscopy were used to locally stimulate β2AR and to measure cytosolic cAMP. Cav3 overexpression increased the number of caveolae and decreased the magnitude of β2AR-cAMP signal. Conversely, Cav3DN expression resulted in an increased β2AR-cAMP response without altering the whole-cell L-type calcium current. Following local stimulation of Cav3DN-expressing ARVMs, β2AR response could only be generated in T-tubules. However, the normally compartmentalized β2AR-cAMP signal became diffuse, similar to the situation observed in heart failure. Finally, overexpression of Cav3 in failing myocytes led to partial β2AR redistribution back into the T-tubules. In conclusion, Cav3 plays a crucial role for the localization of β2AR and compartmentation of β2AR-cAMP signaling to the T-tubules of healthy ARVMs, and overexpression of Cav3 in failing myocytes can partially restore the disrupted localization of these receptors.

  11. NADPH oxidase 4 regulates cardiomyocyte differentiation via redox activation of c-Jun protein and the cis-regulation of GATA-4 gene transcription.

    PubMed

    Murray, Thomas V A; Smyrnias, Ioannis; Shah, Ajay M; Brewer, Alison C

    2013-05-31

    NADPH oxidase 4 (Nox4) generates reactive oxygen species (ROS) that can modulate cellular phenotype and function in part through the redox modulation of the activity of transcription factors. We demonstrate here the potential of Nox4 to drive cardiomyocyte differentiation in pluripotent embryonal carcinoma cells, and we show that this involves the redox activation of c-Jun. This in turn acts to up-regulate GATA-4 expression, one of the earliest markers of cardiotypic differentiation, through a defined and highly conserved cis-acting motif within the GATA-4 promoter. These data therefore suggest a mechanism whereby ROS act in pluripotential cells in vivo to regulate the initial transcription of critical tissue-restricted determinant(s) of the cardiomyocyte phenotype, including GATA-4. The ROS-dependent activation, mediated by Nox4, of widely expressed redox-regulated transcription factors, such as c-Jun, is fundamental to this process.

  12. Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation.

    PubMed

    Lu, Fang-hao; Tian, Zhiliang; Zhang, Wei-hua; Zhao, Ya-jun; Li, Hu-lun; Ren, Huan; Zheng, Hui-shuang; Liu, Chong; Hu, Guang-xia; Tian, Ye; Yang, Bao-feng; Wang, Rui; Xu, Chang-qing

    2010-06-17

    Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

  13. MicroRNAs in the Myocyte Enhancer Factor 2 (MEF2)-regulated Gtl2-Dio3 Noncoding RNA Locus Promote Cardiomyocyte Proliferation by Targeting the Transcriptional Coactivator Cited2.

    PubMed

    Clark, Amanda L; Naya, Francisco J

    2015-09-18

    Understanding cell cycle regulation in postmitotic cardiomyocytes may lead to new therapeutic approaches to regenerate damaged cardiac tissue. We have demonstrated previously that microRNAs encoded by the Gtl2-Dio3 noncoding RNA locus function downstream of the MEF2A transcription factor in skeletal muscle regeneration. We have also reported expression of these miRNAs in the heart. Here we investigated the role of two Gtl2-Dio3 miRNAs, miR-410 and miR-495, in cardiac muscle. Overexpression of miR-410 and miR-495 robustly stimulated cardiomyocyte DNA synthesis and proliferation. Interestingly, unlike our findings in skeletal muscle, these miRNAs did not modulate the activity of the WNT signaling pathway. Instead, these miRNAs targeted Cited2, a coactivator required for proper cardiac development. Consistent with miR-410 and miR-495 overexpression, siRNA knockdown of Cited2 in neonatal cardiomyocytes resulted in robust proliferation. This phenotype was associated with reduced expression of Cdkn1c/p57/Kip2, a cell cycle inhibitor, and increased expression of VEGFA, a growth factor with proliferation-promoting effects. Therefore, miR-410 and miR-495 are among a growing number of miRNAs that have the ability to potently stimulate neonatal cardiomyocyte proliferation.

  14. Endocrine and other physiologic modulators of perinatal cardiomyocyte endowment

    PubMed Central

    Jonker, S S; Louey, S

    2015-01-01

    Immature contractile cardiomyocytes proliferate to rapidly increase cell number, establishing cardiomyocyte endowment in the perinatal period. Developmental changes in cellular maturation, size and attrition further contribute to cardiac anatomy. These physiological processes occur concomitant with a changing hormonal environment as the fetus prepares itself for the transition to extrauterine life. There are complex interactions between endocrine, hemodynamic and nutritional regulators of cardiac development. Birth has been long assumed to be the trigger for major differences between the fetal and postnatal cardiomyocyte growth patterns, but investigations in normally growing sheep and rodents suggest this may not be entirely true; in sheep, these differences are initiated before birth, while in rodents they occur after birth. The aim of this review is to draw together our understanding of the temporal regulation of these signals and cardiomyocyte responses relative to birth. Further, we consider how these dynamics are altered in stressed and suboptimal intrauterine environments. PMID:26432905

  15. The miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation of mouse embryonic cardiomyocytes.

    PubMed

    Xiang, Rui; Lei, Han; Chen, Mianzhi; Li, Qinwei; Sun, Huan; Ai, Jianzhong; Chen, Tielin; Wang, Honglian; Fang, Yin; Zhou, Qin

    2012-02-01

    MicroRNAs (miRNAs) have gradually been recognized as regulators of embryonic development; however, relatively few miRNAs have been identified that regulate cardiac development. A series of recent papers have established an essential role for the miRNA-17-92 (miR-17-92) cluster of miRNAs in the development of the heart. Previous research has shown that the Friend of Gata-2 (FOG-2) is critical for cardiac development. To investigate the possibility that the miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation in mouse embryonic cardiomyocytes we initially used bioinformatics to analyze 3' untranslated regions (3'UTR) of FOG-2 to predict the potential of miR-17-92 to target it. We used luciferase assays to demonstrate that miR-17-5p and miR-20a of miR-17-92 interact with the predicted target sites in the 3'UTR of FOG-2. Furthermore, RT-PCR and Western blot were used to demonstrate the post-transcriptional regulation of FOG-2 by miR-17-92 in embryonic cardiomyocytes from E12.5-day pregnant C57BL/6J mice. Finally, EdU cell assays together with the FOG-2 rescue strategy were employed to evaluate the effect of proliferation on embryonic cardiomyocytes. We first found that the miR-17-5p and miR-20a of miR-17-92 directly target the 3'UTR of FOG-2 and post-transcriptionally repress the expression of FOG-2. Moreover, our findings demonstrated that over-expression of miR-17-92 may inhibit cell proliferation via post-transcriptional repression of FOG-2 in embryonic cardiomyocytes. These results indicate that the miR-17-92 cluster regulates the expression of FOG-2 protein and suggest that the miR-17-92 cluster might play an important role in heart development.

  16. Calcium and mitochondrial metabolism in ceramide-induced cardiomyocyte death.

    PubMed

    Parra, Valentina; Moraga, Francisco; Kuzmicic, Jovan; López-Crisosto, Camila; Troncoso, Rodrigo; Torrealba, Natalia; Criollo, Alfredo; Díaz-Elizondo, Jessica; Rothermel, Beverly A; Quest, Andrew F G; Lavandero, Sergio

    2013-08-01

    Ceramides are important intermediates in the biosynthesis and degradation of sphingolipids that regulate numerous cellular processes, including cell cycle progression, cell growth, differentiation and death. In cardiomyocytes, ceramides induce apoptosis by decreasing mitochondrial membrane potential and promoting cytochrome-c release. Ca(2+) overload is a common feature of all types of cell death. The aim of this study was to determine the effect of ceramides on cytoplasmic Ca(2+) levels, mitochondrial function and cardiomyocyte death. Our data show that C2-ceramide induces apoptosis and necrosis in cultured cardiomyocytes by a mechanism involving increased Ca(2+) influx, mitochondrial network fragmentation and loss of the mitochondrial Ca(2+) buffer capacity. These biochemical events increase cytosolic Ca(2+) levels and trigger cardiomyocyte death via the activation of calpains.

  17. Calcineurin B homologous protein 3 negatively regulates cardiomyocyte hypertrophy via inhibition of glycogen synthase kinase 3 phosphorylation.

    PubMed

    Kobayashi, Soushi; Nakamura, Tomoe Y; Wakabayashi, Shigeo

    2015-07-01

    Cardiac hypertrophy is a leading cause of serious heart diseases. Although many signaling molecules are involved in hypertrophy, the functions of some proteins in this process are still unknown. Calcineurin B homologous protein 3 (CHP3)/tescalcin is an EF-hand Ca(2+)-binding protein that is abundantly expressed in the heart; however, the function of CHP3 is unclear. Here, we aimed to identify the cardiac functions of CHP3. CHP3 was expressed in hearts at a wide range of developmental stages and was specifically detected in neonatal rat ventricular myocytes (NRVMs) but not in cardiac fibroblasts in culture. Moreover, knockdown of CHP3 expression using adenoviral-based RNA interference in NRVMs resulted in enlargement of cardiomyocyte size, concomitant with increased expression of a pathological hypertrophy marker ANP. This same treatment elevated glycogen synthase kinase (GSK3α/β) phosphorylation, which is known to inhibit GSK3 function. In contrast, CHP3 overexpression blocked the insulin-induced phosphorylation of GSK3α/β without affecting the phosphorylation of Akt, which is an upstream kinase of GSK3α/β, in HEK293 cells, and it inhibited both IGF-1-induced phosphorylation of GSK3β and cardiomyocyte hypertrophy in NRVMs. Co-immunoprecipitation experiments revealed that GSK3β interacted with CHP3. However, a Ca(2+)-binding-defective mutation of CHP3 (CHP3-D123A) also interacted with GSK3β and had the same inhibitory effect on GSK3α/β phosphorylation, suggesting that the action of CHP3 was independent of Ca(2+). These findings suggest that CHP3 functions as a novel negative regulator of cardiomyocyte hypertrophy via inhibition of GSK3α/β phosphorylation and subsequent enzymatic activation of GSK3α/β.

  18. Sodium orthovanadate suppresses palmitate-induced cardiomyocyte apoptosis by regulation of the JAK2/STAT3 signaling pathway.

    PubMed

    Liu, Jing; Fu, Hui; Chang, Fen; Wang, Jinlan; Zhang, Shangli; Caudle, Yi; Zhao, Jing; Yin, Deling

    2016-05-01

    Elevated circulatory free fatty acids (FFAs) especially saturated FFAs, such as palmitate (PA), are detrimental to the heart. However, mechanisms responsible for this phenomenon remain unknown. Here, the role of JAK2/STAT3 in PA-induced cytotoxicity was investigated in cardiomyocytes. We demonstrate that PA suppressed the JAK2/STAT3 pathway by dephosphorylation of JAK2 (Y1007/1008) and STAT3 (Y705), and thus blocked the translocation of STAT3 into the nucleus. Conversely, phosphorylation of S727, another phosphorylated site of STAT3, was increased in response to PA treatment. Pretreatment of JNK inhibitor, but not p38 MAPK inhibitor, inhibited STAT3 (S727) activation induced by PA and rescued the phosphorylation of STAT3 (Y705). The data suggested that JNK may be another upstream factor regulating STAT3, and verified the important function of P-STAT3 (Y705) in PA-induced cardiomyocyte apoptosis. Sodium orthovanadate (SOV), a protein tyrosine phosphatase inhibitor, obviously inhibited PA-induced apoptosis by restoring JAK2/STAT3 pathways. This effect was diminished by STAT3 inhibitor Stattic. Collectively, our data suggested a novel mechanism that the inhibition of JAK2/STAT3 activation was responsible for palmitic lipotoxicity and SOV may act as a potential therapeutic agent by targeting JAK2/STAT3 in lipotoxic cardiomyopathy treatment.

  19. β-Adrenergic stimulation activates protein kinase Cε and induces extracellular signal-regulated kinase phosphorylation and cardiomyocyte hypertrophy.

    PubMed

    Li, Lin; Cai, Hongyan; Liu, Hua; Guo, Tao

    2015-06-01

    The cardiac adrenergic signaling pathway is important in the induction of cardiac hypertrophy. The cardiac adrenergic pathway involves two main branches, phospholipase C (PLC)/protein kinase C (PKC) and the adenylate cyclase (cAMPase)/protein kinase A (PKA) signaling pathways. It is hypothesized that PLC/PKC and cAMPase/PKA are activated by the α‑adrenergic receptor (αAR) and the β‑adrenergic receptor (βAR), respectively. Previous studies have demonstrated that exchange protein directly activated by cAMP (Epac), a guanine exchange factor, activates phospholipase Cε. It is possible that there are βAR‑activated PKC pathways mediated by Epac and PLC. In the present study, the role of Epac and PLC in βAR activated PKC pathways in cardiomyocytes was investigated. It was found that PKCε activation and translocation were induced by the βAR agonist, isoproterenol (Iso). Epac agonist 8‑CPT‑2'OMe‑cAMP also enhanced PKCε activation. βAR stimulation activated PKCε in the cardiomyocytes and was regulated by Epac. Iso‑induced change in PKCε was not affected in the cardiomyocytes, which were infected with adenovirus coding rabbit muscle cAMP‑dependent protein kinase inhibitor. However, Iso‑induced PKCε activation was inhibited by the PLC inhibitor, U73122. The results suggested that Iso‑induced PKCε activation was independent of PKA, but was regulated by PLC. To further investigate the downstream signal target of PKCε activation, the expression of phosphorylated extracellular signal‑regulated kinase (pERK)1/2 and the levels of ERK phosphorylation was analyzed. The results revealed that Iso‑induced PKCε activation led to an increase in the expression of pERK1/2. ERK phosphorylation was inhibited by the PKCε inhibitor peptide. Taken together, these data demonstrated that the βAR is able to activate PKCε dependent on Epac and PLC, but independent of PKA.

  20. Ischemic postconditioning and pinacidil suppress calcium overload in anoxia-reoxygenation cardiomyocytes via down-regulation of the calcium-sensing receptor

    PubMed Central

    Deng, Shengli; Yao, Gang

    2016-01-01

    Ischemic postconditioning (IPC) and ATP sensitive potassium channel (KATP) agonists (e.g. pinacidil and diazoxide) postconditioning are effective methods to defeat myocardial ischemia-reperfusion (I/R) injury, but their specific mechanisms of reducing I/R injury are not fully understood. We observed an intracellular free calcium ([Ca2+]i) overload in Anoxia/reoxygenation (A/R) cardiomyocytes, which can be reversed by KATP agonists diazoxide or pinacidil. The calcium-sensing receptor (CaSR) regulates intracellular calcium homeostasis. CaSR was reported to be involved in the I/R-induced apoptosis in rat cardiomyocytes. We therefore hypothesize that IPC and pinacidil postconditioning (PPC) reduce calcium overload in I/R cardiomyocytes by the down-regulation of CaSR. A/R model was established with adult rat caridomyocyte. mRNA and protein expression of CaSR were detected, IPC, PPC and KATP’s effects on [Ca2+]i concentration was assayed too. IPC and PPC ameliorated A/R insult induced [Ca2+]i overload in cardiomyocytes. In addition, they down-regulated the mRNA and protein level of CaSR as we expected. CaSR agonist spermine and KATP blocker glibenclamide offset IPC’s effects on CaSR expression and [Ca2+]i modulation. Our data indicate that CaSR down-regulation contributes to the mitigation of calcium overload in A/R cardiomyocytes, which may partially represents IPC and KATP’s myocardial protective mechanism under I/R circumstances. PMID:27833799

  1. Cardiomyocyte Hypertrophy in Arrhythmogenic Cardiomyopathy.

    PubMed

    Gerçek, Mustafa; Gerçek, Muhammed; Kant, Sebastian; Simsekyilmaz, Sakine; Kassner, Astrid; Milting, Hendrik; Liehn, Elisa A; Leube, Rudolf E; Krusche, Claudia A

    2017-04-01

    Arrhythmogenic cardiomyopathy (AC) is a hereditary disease leading to sudden cardiac death or heart failure. AC pathology is characterized by cardiomyocyte loss and replacement fibrosis. Our goal was to determine whether cardiomyocytes respond to AC progression by pathological hypertrophy. To this end, we examined tissue samples from AC patients with end-stage heart failure and tissue samples that were collected at different disease stages from desmoglein 2-mutant mice, a well characterized AC model. We find that cardiomyocyte diameters are significantly increased in right ventricles of AC patients. Increased mRNA expression of the cardiac stress marker natriuretic peptide B is also observed in the right ventricle of AC patients. Elevated myosin heavy chain 7 mRNA expression is detected in left ventricles. In desmoglein 2-mutant mice, cardiomyocyte diameters are normal during the concealed disease phase but increase significantly after acute disease onset on cardiomyocyte death and fibrotic myocardial remodeling. Hypertrophy progresses further during the chronic disease stage. In parallel, mRNA expression of myosin heavy chain 7 and natriuretic peptide B is up-regulated in both ventricles with right ventricular preference. Calcineurin/nuclear factor of activated T cells (Nfat) signaling, which is linked to pathological hypertrophy, is observed during AC progression, as evidenced by Nfatc2 and Nfatc3 mRNA in cardiomyocytes and increased mRNA of the Nfat target regulator of calcineurin 1. Taken together, we demonstrate that pathological hypertrophy occurs in AC and is secondary to cardiomyocyte loss and cardiac remodeling.

  2. Selective regulation of cardiomyocyte gene expression and cardiac morphogenesis by retinoic acid.

    PubMed

    Dickman, E D; Smith, S M

    1996-05-01

    Early heart development is known to be sensitive to retinoid concentrations; a specific pattern of malformations is observed in both vitamin A-deficiency and retinoid-toxicity states. While the influence of retinoids on early cardiac morphogenesis has been described previously, the effect of retinoids upon cardiomyocyte differentiation and gene expression is largely uncharacterized. We have established an in ovo chick embryo model in which slow-release retinoic acid (RA) induces four distinct cardiac malformations in a dose-dependent fashion. Late primitive streak-stage chick embryos were treated with all-trans-retinoic acid released from anion exchange beads placed on the embryo's left side and then allowed to develop further for 20-24 hr. At low doses (10 and 25 micrograms/ml RA) an abnormal loop structure was observed. At higher doses (50 and 100 micrograms/ml RA) cardia bifida and clustered heart tissue were noted. Situs inversus only occurred after treatment with 100 micrograms/ml RA. RA-treated embryos were subsequently analyzed for appropriate cardiac myocyte differentiation using antibody staining and ELISA analysis to detect sarcomeric myosin heavy chain, tropomyosin, titin, and alpha-actinin protein expression. Alpha-actinin expression was significantly decreased in RA-treated embryos, as compared to DMSO-treated controls. Also, heart contraction rate was depressed after RA exposure. RA exposure did not alter the protein expression levels of sarcomeric myosin heavy chain or tropomyosin. The observed alterations are consistent with suggestions that retinoids may affect both morphogenesis and myofibril formation in the developing heart.

  3. Hormonal regulation of fetal growth.

    PubMed

    Gicquel, C; Le Bouc, Y

    2006-01-01

    Fetal growth is a complex process depending on the genetics of the fetus, the availability of nutrients and oxygen to the fetus, maternal nutrition and various growth factors and hormones of maternal, fetal and placental origin. Hormones play a central role in regulating fetal growth and development. They act as maturational and nutritional signals in utero and control tissue development and differentiation according to the prevailing environmental conditions in the fetus. The insulin-like growth factor (IGF) system, and IGF-I and IGF-II in particular, plays a critical role in fetal and placental growth throughout gestation. Disruption of the IGF1, IGF2 or IGF1R gene retards fetal growth, whereas disruption of IGF2R or overexpression of IGF2 enhances fetal growth. IGF-I stimulates fetal growth when nutrients are available, thereby ensuring that fetal growth is appropriate for the nutrient supply. The production of IGF-I is particularly sensitive to undernutrition. IGF-II plays a key role in placental growth and nutrient transfer. Several key hormone genes involved in embryonic and fetal growth are imprinted. Disruption of this imprinting causes disorders involving growth defects, such as Beckwith-Wiedemann syndrome, which is associated with fetal overgrowth, or Silver-Russell syndrome, which is associated with intrauterine growth retardation. Optimal fetal growth is essential for perinatal survival and has long-term consequences extending into adulthood. Given the high incidence of intrauterine growth retardation and the high risk of metabolic and cardiovascular complications in later life, further clinical and basic research is needed to develop accurate early diagnosis of aberrant fetal growth and novel therapeutic strategies.

  4. Myofibrillogenesis regulator-1 attenuated hypoxia/reoxygenation-induced apoptosis by inhibiting the PERK/Nrf2 pathway in neonatal rat cardiomyocytes.

    PubMed

    Tao, Tian-Qi; Wang, Xiao-Reng; Liu, Mi; Xu, Fei-Fei; Liu, Xiu-Hua

    2015-03-01

    The purpose of this study was to investigate the role of myofibrillogenesis regulator-1 (MR-1) in cardiomyocyte apoptosis induced by hypoxia/reoxygenation (H/R), through protein kinase R-like ER kinase (PERK)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. To address this aim, an H/R model of neonatal rat cardiomyocytes was used. MR-1 was overexpressed using an adenoviral vector system and knocked down using MR-1 specific siRNA. Apoptosis was assessed by using Annexin V/PI double staining, terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling assay, and the Bcl-2/Bax ratio. Western blotting was used to detect the protein levels of MR-1, glucose-regulated protein 78 (GRP78), total and phosphorylated PERK, Nrf2, activating transcription factor 4 (ATF4), C/EBP homologous protein (CHOP), Bcl-2 and Bax. Immunofluorescence staining was used to assess the subcellular location of Nrf2. We found that H/R induced significant apoptosis in neonatal rat cardiomyocytes. MR-1 overexpression attenuated H/R-induced apoptosis, decreased GRP78 (P < 0.01) and CHOP expression (P < 0.05), and increased the Bcl-2/Bax ratio (P < 0.01). MR-1 overexpression suppressed H/R-induced PERK phosphorylation, Nrf2 nuclear translocation, and ATF4 expression (P < 0.01). While MR-1 knockdown aggravated H/R-induced apoptosis, increased expression of GRP78 and CHOP (P < 0.05), and decreased the Bcl-2/Bax ratio (P < 0.01). MR-1 knockdown significantly increased H/R-induced PERK phosphorylation (P < 0.05), Nrf2 nuclear translocation, and ATF4 expression (P < 0.01). These findings suggest that MR-1 alleviates H/R-induced cardiomyocyte apoptosis through inhibition of the PERK/Nrf2 pathway.

  5. Cardiac metabolism and its interactions with contraction, growth, and survival of cardiomyocytes.

    PubMed

    Kolwicz, Stephen C; Purohit, Suneet; Tian, Rong

    2013-08-16

    The network for cardiac fuel metabolism contains intricate sets of interacting pathways that result in both ATP-producing and non-ATP-producing end points for each class of energy substrates. The most salient feature of the network is the metabolic flexibility demonstrated in response to various stimuli, including developmental changes and nutritional status. The heart is also capable of remodeling the metabolic pathways in chronic pathophysiological conditions, which results in modulations of myocardial energetics and contractile function. In a quest to understand the complexity of the cardiac metabolic network, pharmacological and genetic tools have been engaged to manipulate cardiac metabolism in a variety of research models. In concert, a host of therapeutic interventions have been tested clinically to target substrate preference, insulin sensitivity, and mitochondrial function. In addition, the contribution of cellular metabolism to growth, survival, and other signaling pathways through the production of metabolic intermediates has been increasingly noted. In this review, we provide an overview of the cardiac metabolic network and highlight alterations observed in cardiac pathologies as well as strategies used as metabolic therapies in heart failure. Lastly, the ability of metabolic derivatives to intersect growth and survival are also discussed.

  6. MicroRNA-34a regulates high glucose-induced apoptosis in H9c2 cardiomyocytes.

    PubMed

    Zhao, Fang; Li, Bo; Wei, Yin-zhi; Zhou, Bin; Wang, Han; Chen, Ming; Gan, Xue-dong; Wang, Zhao-hui; Xiong, Shi-xi

    2013-12-01

    Hyperglycemia is an important initiator of cardiovascular disease, contributing to the development of cardiomyocyte death and diabetic complications. The purpose of the present study was to investigate whether high glucose state could induce apoptosis of rat cardiomyocyte cell line H9c2 through microRNA-mediated Bcl-2 signaling pathway. The expression of miR-34a and Bcl-2 mRNA was detected by using real-time PCR. Western blotting was used to examine the changes in apoptosis-associated protein Bcl-2. Apoptosis of H9c2 cells was tested by using flow cytometry. The results showed that the expression of miR-34a was significantly elevated and that of Bcl-2 was strongly reduced, and apoptosis of cardiomyocytes was apparently increased in the high-glucose-treated H9c2 cells as compared with normal-glucose-treated controls. In addition, we identified Bcl-2 gene was the target of miR-34a. miR-34a mimics reduced the expression of Bcl-2 and increased glucose-induced apoptosis, but miR-34a inhibitor acted as the opposite mediator. Our data demonstrate that miR-34a contributes to high glucose-induced decreases in Bcl-2 expression and subsequent cardiomyocyte apoptosis.

  7. Differential regulation of DNA methylation versus histone acetylation in cardiomyocytes during HHcy in vitro and in vivo: an epigenetic mechanism.

    PubMed

    Chaturvedi, Pankaj; Kalani, Anuradha; Givvimani, Srikanth; Kamat, Pradip Kumar; Familtseva, Anastasia; Tyagi, Suresh C

    2014-04-01

    The mechanisms of homocysteine-mediated cardiac threats are poorly understood. Homocysteine, being the precursor to S-adenosyl methionine (a methyl donor) through methionine, is indirectly involved in methylation phenomena for DNA, RNA, and protein. We reported previously that cardiac-specific deletion of N-methyl-d-aspartate receptor-1 (NMDAR1) ameliorates homocysteine-posed cardiac threats, and in this study, we aim to explore the role of NMDAR1 in epigenetic mechanisms of heart failure, using cardiomyocytes during hyperhomocysteinemia (HHcy). High homocysteine levels activate NMDAR1, which consequently leads to abnormal DNA methylation vs. histone acetylation through modulation of DNA methyltransferase 1 (DNMT1), HDAC1, miRNAs, and MMP9 in cardiomyocytes. HL-1 cardiomyocytes cultured in Claycomb media were treated with 100 μM homocysteine in a dose-dependent manner. NMDAR1 antagonist (MK801) was added in the absence and presence of homocysteine at 10 μM in a dose-dependent manner. The expression of DNMT1, histone deacetylase 1 (HDAC1), NMDAR1, microRNA (miR)-133a, and miR-499 was assessed by real-time PCR as well as Western blotting. Methylation and acetylation levels were determined by checking 5'-methylcytosine DNA methylation and chromatin immunoprecipitation. Hyperhomocysteinemic mouse models (CBS+/-) were used to confirm the results in vivo. In HHcy, the expression of NMDAR1, DNMT1, and matrix metalloproteinase 9 increased with increase in H3K9 acetylation, while HDAC1, miR-133a, and miR-499 decreased in cardiomyocytes. Similar results were obtained in heart tissue of CBS+/- mouse. High homocysteine levels instigate cardiovascular remodeling through NMDAR1, miR-133a, miR-499, and DNMT1. A decrease in HDAC1 and an increase in H3K9 acetylation and DNA methylation are suggestive of chromatin remodeling in HHcy.

  8. Regulation of cardiac autophagy by insulin-like growth factor 1.

    PubMed

    Troncoso, Rodrigo; Díaz-Elizondo, Jessica; Espinoza, Sandra P; Navarro-Marquez, Mario F; Oyarzún, Alejandra P; Riquelme, Jaime A; Garcia-Carvajal, Ivonne; Díaz-Araya, Guillermo; García, Lorena; Hill, Joseph A; Lavandero, Sergio

    2013-07-01

    Insulin-like growth factor-1 (IGF-1) signaling is a key pathway in the control of cell growth and survival. Three critical nodes in the IGF-1 signaling pathway have been described in cardiomyocytes: protein kinase Akt/mammalian target of rapamycin (mTOR), Ras/Raf/extracellular signal-regulated kinase (ERK), and phospholipase C (PLC)/inositol 1,4,5-triphosphate (InsP3 )/Ca(2+) . The Akt/mTOR and Ras/Raf/ERK signaling arms govern survival in the settings of cardiac stress and hypertrophic growth. By contrast, PLC/InsP3 /Ca(2+) functions to regulate metabolic adaptability and gene transcription. Autophagy is a catabolic process involved in protein degradation, organelle turnover, and nonselective breakdown of cytoplasmic components during nutrient starvation or stress. In the heart, autophagy is observed in a variety of human pathologies, where it can be either adaptive or maladaptive, depending on the context. We proposed the hypothesis that IGF-1 protects the heart by rescuing the mitochondrial metabolism and the energetics state, reducing cell death and controls the potentially exacerbate autophagic response to nutritional stress. In light of the importance of IGF-1 and autophagy in the heart, we review here IGF-1 signaling and autophagy regulation in the context of cardiomyocyte nutritional stress.

  9. [Plant hormones, plant growth regulators].

    PubMed

    Végvári, György; Vidéki, Edina

    2014-06-29

    Plants seem to be rather defenceless, they are unable to do motion, have no nervous system or immune system unlike animals. Besides this, plants do have hormones, though these substances are produced not in glands. In view of their complexity they lagged behind animals, however, plant organisms show large scale integration in their structure and function. In higher plants, such as in animals, the intercellular communication is fulfilled through chemical messengers. These specific compounds in plants are called phytohormones, or in a wide sense, bioregulators. Even a small quantity of these endogenous organic compounds are able to regulate the operation, growth and development of higher plants, and keep the connection between cells, tissues and synergy between organs. Since they do not have nervous and immume systems, phytohormones play essential role in plants' life.

  10. A Proliferative Burst During Preadolescence Establishes the Final Cardiomyocyte Number

    PubMed Central

    Naqvi, Nawazish; Li, Ming; Calvert, John W.; Tejada, Thor; Lambert, Jonathan P.; Wu, Jianxin; Kesteven, Scott H.; Holman, Sara R.; Matsuda, Torahiro; Lovelock, Joshua D.; Howard, Wesley W.; Iismaa, Siiri E.; Chan, Andrea Y.; Crawford, Brian H.; Wagner, Mary B.; Martin, David I. K.; Lefer, David J.; Graham, Robert M.; Husain, Ahsan

    2014-01-01

    SUMMARY It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here we show thata thyroid hormone surge activates the IGF-1/IGF1-R/Akt pathway on postnatal day-15andinitiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day15 is intermediate between that observed at postnatal day-2 and -21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases. PMID:24813607

  11. A proliferative burst during preadolescence establishes the final cardiomyocyte number.

    PubMed

    Naqvi, Nawazish; Li, Ming; Calvert, John W; Tejada, Thor; Lambert, Jonathan P; Wu, Jianxin; Kesteven, Scott H; Holman, Sara R; Matsuda, Torahiro; Lovelock, Joshua D; Howard, Wesley W; Iismaa, Siiri E; Chan, Andrea Y; Crawford, Brian H; Wagner, Mary B; Martin, David I K; Lefer, David J; Graham, Robert M; Husain, Ahsan

    2014-05-08

    It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases.

  12. ErbB2 is required for cardiomyocyte proliferation in murine neonatal hearts

    PubMed Central

    Ma, Hong; Yin, Chaoying; Zhang, Yingao; Qian, Li; Liu, Jiandong

    2017-01-01

    It has been long recognized that the mammalian heart loses its proliferative capacity soon after birth, yet, the molecular basis of this loss of cardiac proliferation postnatally is largely unknown. In this study, we found that cardiac ErbB2, a member of the epidermal growth factor receptor family, exhibits a rapid and dramatic decline in expression at the neonatal stage. We further demonstrate that conditional ablation of ErbB2 in the ventricular myocardium results in upregulation of negative cell cycle regulators and a significant reduction in cardiomyocyte proliferation during the narrow neonatal proliferative time window. Together, our data reveal a positive correlation between the expression levels of ErbB2 with neonatal cardiomyocyte proliferation and suggest that reduction in cardiac ErbB2 expression may contribute to the loss of postnatal cardiomyocyte proliferative capacity. PMID:27390088

  13. Autonomous regulation of growth cone filopodia.

    PubMed

    Rehder, V; Cheng, S

    1998-02-05

    The fan-shaped array of filopodia is the first site of contact of a neuronal growth cone with molecules encountered during neuronal pathfinding. Filopodia are highly dynamic structures, and the "action radius" of a growth cone is strongly determined by the length and number of its filopodia. Since interactions of filopodia with instructive cues in the vicinity of the growth cone can have effects on growth cone morphology within minutes, it has to be assumed that a large part of the signaling underlying such morphological changes resides locally within the growth cone proper. In this study, we tested the hypothesis that two important growth cone parameters-namely, the length and number of its filopodia-are regulated autonomously in the growth cone. We previously demonstrated in identified neurons from the snail Helisoma trivolvis that filopodial length and number are regulated by intracellular calcium. Here, we investigated filopodial dynamics and their regulation by the second-messenger calcium in growth cones which were physically isolated from their parent neuron by neurite transection. Our results show that isolated growth cones have longer but fewer filopodia than growth cones attached to their parent cell. These isolated growth cones, however, are fully capable of undergoing calcium-induced cytoskeletal changes, suggesting that the machinery necessary to perform changes in filopodial length and number is fully intrinsic to the growth cone proper.

  14. Gonads directly regulate growth in teleosts.

    PubMed

    Bhatta, Sandip; Iwai, Toshiharu; Miura, Chiemi; Higuchi, Masato; Shimizu-Yamaguchi, Sonoko; Fukada, Haruhisa; Miura, Takeshi

    2012-07-10

    In general, there is a relationship between growth and reproduction, and gonads are known to be important organs for growth, but direct evidence for their role is lacking. Here, using a fish model, we report direct evidence that gonads are endocrine organs equal to the pituitary in controlling body growth. Gonadal loss of function, gain of function, and rescue of growth were investigated in tilapia. Gonadectomy experiments were carried out in juvenile males and females. Gonadectomy significantly retarded growth compared with controls; however, this retardation was rescued by the implantation of extirpated gonads. Because gonads express growth hormone, it is possible that gonads control body growth through the secretion of growth hormone and/or other endocrine factors. We propose that gonads are integral players in the dynamic regulation of growth in teleosts.

  15. Mitochondrial fission is required for cardiomyocyte hypertrophy mediated by a Ca2+-calcineurin signaling pathway

    PubMed Central

    Pennanen, Christian; Parra, Valentina; López-Crisosto, Camila; Morales, Pablo E.; del Campo, Andrea; Gutierrez, Tomás; Rivera-Mejías, Pablo; Kuzmicic, Jovan; Chiong, Mario; Zorzano, Antonio; Rothermel, Beverly A.; Lavandero, Sergio

    2014-01-01

    ABSTRACT Cardiomyocyte hypertrophy has been associated with diminished mitochondrial metabolism. Mitochondria are crucial organelles for the production of ATP, and their morphology and function are regulated by the dynamic processes of fusion and fission. The relationship between mitochondrial dynamics and cardiomyocyte hypertrophy is still poorly understood. Here, we show that treatment of cultured neonatal rat cardiomyocytes with the hypertrophic agonist norepinephrine promotes mitochondrial fission (characterized by a decrease in mitochondrial mean volume and an increase in the relative number of mitochondria per cell) and a decrease in mitochondrial function. We demonstrate that norepinephrine acts through α1-adrenergic receptors to increase cytoplasmic Ca2+, activating calcineurin and promoting migration of the fission protein Drp1 (encoded by Dnml1) to mitochondria. Dominant-negative Drp1 (K38A) not only prevented mitochondrial fission, it also blocked hypertrophic growth of cardiomyocytes in response to norepinephrine. Remarkably, an antisense adenovirus against the fusion protein Mfn2 (AsMfn2) was sufficient to increase mitochondrial fission and stimulate a hypertrophic response without agonist treatment. Collectively, these results demonstrate the importance of mitochondrial dynamics in the development of cardiomyocyte hypertrophy and metabolic remodeling. PMID:24777478

  16. Mitochondrial fission is required for cardiomyocyte hypertrophy mediated by a Ca2+-calcineurin signaling pathway.

    PubMed

    Pennanen, Christian; Parra, Valentina; López-Crisosto, Camila; Morales, Pablo E; Del Campo, Andrea; Gutierrez, Tomás; Rivera-Mejías, Pablo; Kuzmicic, Jovan; Chiong, Mario; Zorzano, Antonio; Rothermel, Beverly A; Lavandero, Sergio

    2014-06-15

    Cardiomyocyte hypertrophy has been associated with diminished mitochondrial metabolism. Mitochondria are crucial organelles for the production of ATP, and their morphology and function are regulated by the dynamic processes of fusion and fission. The relationship between mitochondrial dynamics and cardiomyocyte hypertrophy is still poorly understood. Here, we show that treatment of cultured neonatal rat cardiomyocytes with the hypertrophic agonist norepinephrine promotes mitochondrial fission (characterized by a decrease in mitochondrial mean volume and an increase in the relative number of mitochondria per cell) and a decrease in mitochondrial function. We demonstrate that norepinephrine acts through α1-adrenergic receptors to increase cytoplasmic Ca(2+), activating calcineurin and promoting migration of the fission protein Drp1 (encoded by Dnml1) to mitochondria. Dominant-negative Drp1 (K38A) not only prevented mitochondrial fission, it also blocked hypertrophic growth of cardiomyocytes in response to norepinephrine. Remarkably, an antisense adenovirus against the fusion protein Mfn2 (AsMfn2) was sufficient to increase mitochondrial fission and stimulate a hypertrophic response without agonist treatment. Collectively, these results demonstrate the importance of mitochondrial dynamics in the development of cardiomyocyte hypertrophy and metabolic remodeling.

  17. Spontaneous Calcium Oscillations Regulate Human Cardiac Progenitor Cell Growth

    PubMed Central

    Ferreira-Martins, João; Rondon-Clavo, Carlos; Tugal, Derin; Korn, Justin A; Rizzi, Roberto; Padin-Iruegas, Maria Elena; Ottolenghi, Sergio; De Angelis, Antonella; Urbanek, Konrad; Iwata, Noriko; D’Amario, Domenico; Hosoda, Toru; Leri, Annarosa; Kajstura, Jan; Anversa, Piero; Rota, Marcello

    2009-01-01

    Rationale The adult heart possesses a pool of progenitor cells stored in myocardial niches but the mechanisms involved in the activation of this cell compartment are currently unknown. Objective Ca2+ promotes cell growth raising the possibility that changes in intracellular Ca2+ initiate division of c-kit-positive human cardiac progenitor cells (hCPCs) and determine their fate. Methods and Results Ca2+ oscillations were identified in hCPCs and these events occurred independently from coupling with cardiomyocytes or the presence of extracellular Ca2+. These findings were confirmed in the heart of transgenic mice in which EGFP was under the control of the c-kit-promoter. Ca2+ oscillations in hCPCs were regulated by the release of Ca2+ from the ER through activation of inositol 1,4,5-triphosphate receptors (IP3Rs) and the re-uptake of Ca2+ by the sarco/endoplasmic reticulum Ca2+ pump (SERCA). IP3Rs and SERCA were highly expressed in hCPCs while ryanodine receptors were not detected. Although Na+-Ca2+ exchanger, store-operated Ca2+-channels and plasma membrane Ca2+-pump were present and functional in hCPCs, they had no direct effects on Ca2+ oscillations. Conversely, Ca2+ oscillations and their frequency markedly increased with ATP and histamine which activated purinoceptors and histamine-1 receptors highly expressed in hCPCs. Importantly, Ca2+ oscillations in hCPCs were coupled with the entry of cells into the cell cycle and BrdUrd incorporation. Induction of Ca2+ oscillations in hCPCs prior to their intramyocardial delivery to infarcted hearts was associated with enhanced engraftment and expansion of these cells promoting the generation of a large myocyte progeny. Conclusion IP3R-mediated Ca2+ mobilization control hCPC growth and their regenerative potential. PMID:19745162

  18. Regulation of muscle growth in neonates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review reports recent findings on the multiple factors that regulate skeletal muscle growth in neonates. Skeletal muscle is the fastest growing protein mass in neonates. The high rate of neonatal muscle growth is due to accelerated rates of protein synthesis accompanied by the rapid accumulatio...

  19. The alteration of protein prenylation induces cardiomyocyte hypertrophy through Rheb-mTORC1 signalling and leads to chronic heart failure.

    PubMed

    Xu, Na; Guan, Shan; Chen, Zhong; Yu, Yang; Xie, Jun; Pan, Fei-Yan; Zhao, Ning-Wei; Liu, Li; Yang, Zhong-Zhou; Gao, Xiang; Xu, Biao; Li, Chao-Jun

    2015-04-01

    G protein-regulated cell function is crucial for cardiomyocytes, and any deregulation of its gene expression or protein modification can lead to pathological cardiac hypertrophy. Herein, we report that protein prenylation, a lipidic modification of G proteins that facilitates their association with the cell membrane, might control the process of cardiomyocyte hypertrophy. We found that geranylgeranyl diphosphate synthase (GGPPS), a key enzyme involved in protein prenylation, played a critical role in postnatal heart growth by regulating cardiomyocyte size. Cardiac-specific knockout of GGPPS in mice led to spontaneous cardiac hypertrophy, beginning from week 4, accompanied by the persistent enlargement of cardiomyocytes. This hypertrophic effect occurred by altered prenylation of G proteins. Evaluation of the prenylation, membrane association and hydrophobicity showed that Rheb was hyperactivated and increased mTORC1 signalling pathway after GGPPS deletion. Protein farnesylation or mTORC1 inhibition blocked GGPPS knockdown-induced mTORC1 activation and suppressed the larger neonatal rat ventricle myocyte size and cardiomyocyte hypertrophy in vivo, demonstrating a central role of the FPP-Rheb-mTORC1 axis for GGPPS deficiency-induced cardiomyocyte hypertrophy. The sustained cardiomyocyte hypertrophy progressively provoked cardiac decompensation and dysfunction, ultimately causing heart failure and adult death. Importantly, GGPPS was down-regulated in the hypertrophic hearts of mice subjected to transverse aortic constriction (TAC) and in failing human hearts. Moreover, HPLC-MS/MS detection revealed that the myocardial farnesyl diphosphate (FPP):geranylgeranyl diphosphate (GGPP) ratio was enhanced after pressure overload. Our observations conclude that the alteration of protein prenylation promotes cardiomyocyte hypertrophic growth, which acts as a potential cause for pathogenesis of heart failure and may provide a new molecular target for hypertrophic heart disease

  20. Chemical Growth Regulators for Guayule Plants

    NASA Technical Reports Server (NTRS)

    Dastoor, M. N.; Schubert, W. W.; Petersen, G. R.

    1982-01-01

    Test Tubes containing Guayule - tissue cultures were used in experiments to test effects of chemical-growth regulators. The shoots grew in response to addition of 2-(3,4-dichlorophenoxy)-triethylamine (triethylamine (TEA) derivative) to agar medium. Preliminary results indicate that a class of compounds that promotes growth in soil may also promote growth in a culture medium. Further experiments are needed to define the effect of the TEA derivative.

  1. Resistance to cardiomyocyte hypertrophy in ae3 −/− mice, deficient in the AE3 Cl−/HCO3− exchanger

    PubMed Central

    2014-01-01

    Background Cardiac hypertrophy is central to the etiology of heart failure. Understanding the molecular pathways promoting cardiac hypertrophy may identify new targets for therapeutic intervention. Sodium-proton exchanger (NHE1) activity and expression levels in the heart are elevated in many models of hypertrophy through protein kinase C (PKC)/MAPK/ERK/p90RSK pathway stimulation. Sustained NHE1 activity, however, requires an acid-loading pathway. Evidence suggests that the Cl−/HCO3− exchanger, AE3, provides this acid load. Here we explored the role of AE3 in the hypertrophic growth cascade of cardiomyocytes. Methods AE3-deficient (ae3 −/− ) mice were compared to wildtype (WT) littermates to examine the role of AE3 protein in the development of cardiomyocyte hypertrophy. Mouse hearts were assessed by echocardiography. As well, responses of cultured cardiomyocytes to hypertrophic stimuli were measured. pH regulation capacity of ae3 −/− and WT cardiomyocytes was assessed in cultured cells loaded with the pH-sensitive dye, BCECF-AM. Results ae3 −/− mice were indistinguishable from wild type (WT) mice in terms of cardiovascular performance. Stimulation of ae3 −/− cardiomyocytes with hypertrophic agonists did not increase cardiac growth or reactivate the fetal gene program. ae3 −/− mice are thus protected from pro-hypertrophic stimulation. Steady state intracellular pH (pHi) in ae3 −/− cardiomyocytes was not significantly different from WT, but the rate of recovery of pHi from imposed alkalosis was significantly slower in ae3 −/− cardiomyocytes. Conclusions These data reveal the importance of AE3-mediated Cl−/HCO3− exchange in cardiovascular pH regulation and the development of cardiomyocyte hypertrophy. Pharmacological antagonism of AE3 is an attractive approach in the treatment of cardiac hypertrophy. PMID:25047106

  2. The pro-angiogenic cytokine pleiotrophin potentiates cardiomyocyte apoptosis through inhibition of endogenous AKT/PKB activity.

    PubMed

    Li, Jinliang; Wei, Hong; Chesley, Alan; Moon, Chanil; Krawczyk, Melissa; Volkova, Maria; Ziman, Bruce; Margulies, Kenneth B; Talan, Mark; Crow, Michael T; Boheler, Kenneth R

    2007-11-30

    Pleiotrophin is a development-regulated cytokine and growth factor that can promote angiogenesis, cell proliferation, or differentiation, and it has been reported to have neovasculogenic effects in damaged heart. Developmentally, it is prominently expressed in fetal and neonatal hearts, but it is minimally expressed in normal adult heart. Conversely, we show in a rat model of myocardial infarction and in human dilated cardiomyopathy that pleiotrophin is markedly up-regulated. To elucidate the effects of pleiotrophin on cardiac contractile cells, we employed primary cultures of rat neonatal and adult cardiomyocytes. We show that pleiotrophin is released from cardiomyocytes in vitro in response to hypoxia and that the addition of recombinant pleiotrophin promotes caspase-mediated genomic DNA fragmentation in a dose- and time-dependent manner. Functionally, it potentiates the apoptotic response of neonatal cardiomyocytes to hypoxic stress and to ultraviolet irradiation and of adult cardiomyocytes to hypoxia-reoxygenation. Moreover, UV-induced apoptosis in neonatal cardiomyocytes can be partially inhibited by small interfering RNA-mediated knockdown of endogenous pleiotrophin. Mechanistically, pleiotrophin antagonizes IGF-1 associated Ser-473 phosphorylation of AKT/PKB, and it concomitantly decreases both BAD and GSK3beta phosphorylation. Adenoviral expression of constitutively active AKT and lithium chloride-mediated inhibition of GSK3beta reduce the potentiated programmed cell death elicited by pleiotrophin. These latter data indicate that pleiotrophin potentiates cardiomyocyte cell death, at least partially, through inhibition of AKT signaling. In conclusion, we have uncovered a novel function for pleiotrophin on heart cells following injury. It fosters cardiomyocyte programmed cell death in response to pro-apoptotic stress, which may be critical to myocardial injury repair.

  3. RhoA signaling in cardiomyocytes protects against stress-induced heart failure but facilitates cardiac fibrosis.

    PubMed

    Lauriol, Jessica; Keith, Kimberly; Jaffré, Fabrice; Couvillon, Anthony; Saci, Abdel; Goonasekera, Sanjeewa A; McCarthy, Jason R; Kessinger, Chase W; Wang, Jianxun; Ke, Qingen; Kang, Peter M; Molkentin, Jeffery D; Carpenter, Christopher; Kontaridis, Maria I

    2014-10-21

    The Ras-related guanosine triphosphatase RhoA mediates pathological cardiac hypertrophy, but also promotes cell survival and is cardioprotective after ischemia/reperfusion injury. To understand how RhoA mediates these opposing roles in the myocardium, we generated mice with a cardiomyocyte-specific deletion of RhoA. Under normal conditions, the hearts from these mice showed functional, structural, and growth parameters similar to control mice. Additionally, the hearts of the cardiomyocyte-specific, RhoA-deficient mice subjected to transverse aortic constriction (TAC)-a procedure that induces pressure overload and, if prolonged, heart failure-exhibited a similar amount of hypertrophy as those of the wild-type mice subjected to TAC. Thus, neither normal cardiac homeostasis nor the initiation of compensatory hypertrophy required RhoA in cardiomyocytes. However, in response to chronic TAC, hearts from mice with cardiomyocyte-specific deletion of RhoA showed greater dilation, with thinner ventricular walls and larger chamber dimensions, and more impaired contractile function than those from control mice subjected to chronic TAC. These effects were associated with aberrant calcium signaling, as well as decreased activity of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and AKT. In addition, hearts from mice with cardiomyocyte-specific RhoA deficiency also showed less fibrosis in response to chronic TAC, with decreased transcriptional activation of genes involved in fibrosis, including myocardin response transcription factor (MRTF) and serum response factor (SRF), suggesting that the fibrotic response to stress in the heart depends on cardiomyocyte-specific RhoA signaling. Our data indicated that RhoA regulates multiple pathways in cardiomyocytes, mediating both cardioprotective (hypertrophy without dilation) and cardio-deleterious effects (fibrosis).

  4. Migration of cardiomyocytes is essential for heart regeneration in zebrafish.

    PubMed

    Itou, Junji; Oishi, Isao; Kawakami, Hiroko; Glass, Tiffany J; Richter, Jenna; Johnson, Austin; Lund, Troy C; Kawakami, Yasuhiko

    2012-11-01

    Adult zebrafish possess a significant ability to regenerate injured heart tissue through proliferation of pre-existing cardiomyocytes, which contrasts with the inability of mammals to do so after the immediate postnatal period. Zebrafish therefore provide a model system in which to study how an injured heart can be repaired. However, it remains unknown what important processes cardiomyocytes are involved in other than partial de-differentiation and proliferation. Here we show that migration of cardiomyocytes to the injury site is essential for heart regeneration. Ventricular amputation induced expression of cxcl12a and cxcr4b, genes encoding a chemokine ligand and its receptor. We found that cxcl12a was expressed in the epicardial tissue and that Cxcr4 was expressed in cardiomyocytes. We show that pharmacological blocking of Cxcr4 function as well as genetic loss of cxcr4b function causes failure to regenerate the heart after ventricular resection. Cardiomyocyte proliferation was not affected but a large portion of proliferating cardiomyocytes remained localized outside the injury site. A photoconvertible fluorescent reporter-based cardiomyocyte-tracing assay demonstrates that cardiomyocytes migrated into the injury site in control hearts but that migration was inhibited in the Cxcr4-blocked hearts. By contrast, the epicardial cells and vascular endothelial cells were not affected by blocking Cxcr4 function. Our data show that the migration of cardiomyocytes into the injury site is regulated independently of proliferation, and that coordination of both processes is necessary for heart regeneration.

  5. FGF signalling regulates bone growth through autophagy.

    PubMed

    Cinque, Laura; Forrester, Alison; Bartolomeo, Rosa; Svelto, Maria; Venditti, Rossella; Montefusco, Sandro; Polishchuk, Elena; Nusco, Edoardo; Rossi, Antonio; Medina, Diego L; Polishchuk, Roman; De Matteis, Maria Antonietta; Settembre, Carmine

    2015-12-10

    Skeletal growth relies on both biosynthetic and catabolic processes. While the role of the former is clearly established, how the latter contributes to growth-promoting pathways is less understood. Macroautophagy, hereafter referred to as autophagy, is a catabolic process that plays a fundamental part in tissue homeostasis. We investigated the role of autophagy during bone growth, which is mediated by chondrocyte rate of proliferation, hypertrophic differentiation and extracellular matrix (ECM) deposition in growth plates. Here we show that autophagy is induced in growth-plate chondrocytes during post-natal development and regulates the secretion of type II collagen (Col2), the major component of cartilage ECM. Mice lacking the autophagy related gene 7 (Atg7) in chondrocytes experience endoplasmic reticulum storage of type II procollagen (PC2) and defective formation of the Col2 fibrillary network in the ECM. Surprisingly, post-natal induction of chondrocyte autophagy is mediated by the growth factor FGF18 through FGFR4 and JNK-dependent activation of the autophagy initiation complex VPS34-beclin-1. Autophagy is completely suppressed in growth plates from Fgf18(-/-) embryos, while Fgf18(+/-) heterozygous and Fgfr4(-/-) mice fail to induce autophagy during post-natal development and show decreased Col2 levels in the growth plate. Strikingly, the Fgf18(+/-) and Fgfr4(-/-) phenotypes can be rescued in vivo by pharmacological activation of autophagy, pointing to autophagy as a novel effector of FGF signalling in bone. These data demonstrate that autophagy is a developmentally regulated process necessary for bone growth, and identify FGF signalling as a crucial regulator of autophagy in chondrocytes.

  6. IL-10 Inhibits the NF-κB and ERK/MAPK-Mediated Production of Pro-Inflammatory Mediators by Up-Regulation of SOCS-3 in Trypanosoma cruzi-Infected Cardiomyocytes

    PubMed Central

    Siffo, Sofía; Mirkin, Gerardo A.; Goren, Nora B.

    2013-01-01

    Trypanosoma cruzi (T. cruzi) infection produces an intense inflammatory response which is critical for the control of the evolution of Chagas’ disease. Interleukin (IL)-10 is one of the most important anti-inflammatory cytokines identified as modulator of the inflammatory reaction. This work shows that exogenous addition of IL-10 inhibited ERK1/2 and NF-κB activation and reduced inducible nitric oxide synthase (NOS2), metalloprotease (MMP) -9 and MMP-2 expression and activities, as well as tumour necrosis factor (TNF)-α and interleukin (IL)-6 expression, in T. cruzi-infected cardiomyocytes. We found that T. cruzi and IL-10 promote STAT3 phosphorylation and up-regulate the expression of suppressor of cytokine signalling (SOCS)-3 thereby preventing NF-κB nuclear translocation and ERK1/2 phosphorylation. Specific knockdown of SOCS-3 by small interfering RNA (siRNA) impeded the IL-10-mediated inhibition of NF-κB and ERK1/2 activation. As a result, the levels of studied pro-inflammatory mediators were restored in infected cardiomyocytes. Our study reports the first evidence that T. cruzi up- regulates SOCS-3 expression and highlights the relevance of IL-10 in the modulation of pro-inflammatory response of cardiomyocytes in Chagas’ disease. PMID:24260222

  7. The choroid as a sclera growth regulator.

    PubMed

    Summers, Jody A

    2013-09-01

    Emmetropization is a vision dependent mechanism that attempts to minimize refractive error through coordinated growth of the cornea, lens and sclera such that the axial length matches the focal length of the eye. It is generally accepted that this visually guided eye growth is controlled via a cascade of locally generated chemical events that are initiated in the retina and ultimately cause changes in scleral extracellular matrix (ECM) remodeling which lead to changes in eye size and refraction. Of much interest, therefore, are the molecular mechanisms that underpin emmetropization and visually guided ocular growth. The choroid, a highly vascularized layer located between the retina and the sclera is uniquely situated to relay retina-derived signals to the sclera to effect changes in ECM synthesis and ocular size. Studies initiated by Josh Wallman clearly demonstrate that the choroid plays an active role in emmetropization, both by modulation of its thickness to adjust the retina to the focal plane of the eye (choroidal accommodation), and well as through the release of growth factors that have the potential to regulate scleral extracellular matrix remodeling. His discoveries prompted numerous investigations on the molecular composition of the choroid and changes in gene expression associated with visually guided ocular growth. This article will review molecular and functional studies of the choroid to provide support for the hypothesis that the choroid is a source of sclera growth regulators that effect changes in ocular growth in response to visual stimuli.

  8. Regulation of bone mass by growth hormone.

    PubMed

    Olney, Robert C

    2003-09-01

    Growth hormone (GH) is a peptide hormone secreted from the pituitary gland under the control of the hypothalamus. It has a many actions in the body, including regulating a number of metabolic pathways. Some, but not all, of its effects are mediated through insulin-like growth factor-I (IGF-I). Both GH and IGF-I play significant roles in the regulation of growth and bone metabolism and hence are regulators of bone mass. Bone mass increases steadily through childhood, peaking in the mid 20s. Subsequently, there is a slow decline that accelerates in late life. During childhood, the accumulation in bone mass is a combination of bone growth and bone remodeling. Bone remodeling is the process of new bone formation by osteoblasts and bone resorption by osteoclasts. GH directly and through IGF-I stimulates osteoblast proliferation and activity, promoting bone formation. It also stimulates osteoclast differentiation and activity, promoting bone resorption. The result is an increase in the overall rate of bone remodeling, with a net effect of bone accumulation. The absence of GH results in a reduced rate of bone remodeling and a gradual loss of bone mineral density. Bone growth primarily occurs at the epiphyseal growth plates and is the result of the proliferation and differentiation of chondrocytes. GH has direct effects on these chondrocytes, but primarily regulates this function through IGF-I, which stimulates the proliferation of and matrix production by these cells. GH deficiency severely limits bone growth and hence the accumulation of bone mass. GH deficiency is not an uncommon complication in oncology and has long-term effects on bone health.

  9. MiR-145-5p regulates hypoxia-induced inflammatory response and apoptosis in cardiomyocytes by targeting CD40.

    PubMed

    Yuan, Ming; Zhang, Liwei; You, Fei; Zhou, Jingyu; Ma, Yongjiang; Yang, Feifei; Tao, Ling

    2017-03-09

    An increasing body of evidence indicates that inflammation and apoptosis are involved in the development of acute myocardial infarction (AMI). In this study, we sought to investigate the specific role and the underlying regulatory mechanism of miR-145-5p in myocardial ischemic injury. H9c2 cardiac cells were exposed to hypoxia to establish a model of myocardial hypoxic/ischemic injury. We found that miR-145-5p was notably down-regulated, while CD40 expression was highly elevated in H9c2 cells following exposure to acute hypoxia. Additionally, hypoxia markedly enhanced the inflammatory response, as reflected by an increase in the secretion of the cytokines IL-1β, TNF-α, and IL-6, whereas the introduction of miR-145-5p effectively suppressed inflammatory factor production triggered by hypoxia. Furthermore, we observed hypoxia stimulation significantly augmented apoptosis accompanied by a decrease in the expression of Bcl-2 and an increase in the expression of Bax, Caspase-3, and Caspase-9. However, augmentation of miR-145-5p led to a dramatic prevention of hypoxia-induced apoptosis. Importantly, we identified CD40 as a direct target of miR-145-5p. Interestingly, the depletion of CD40 with small interfering RNAs (siRNAs) apparently repressed the production of inflammatory cytokines and apoptosis in the setting of acute hypoxic treated. Taken together, these data demonstrated that miR-145-5p may function as a cardiac-protective molecule in myocardial ischemic injury by ameliorating inflammation and apoptosis via negative regulation of CD40. The study gives evidence that miR-145-5p provides an interesting strategy for protecting cardiomyocytes from hypoxia-induced inflammatory response and apoptosis.

  10. Mathematics Coursework Regulates Growth in Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, Xin; Wilkins, Jesse L. M.

    2007-01-01

    Using data from the Longitudinal Study of American Youth (LSAY), we examined the extent to which students' mathematics coursework regulates (influences) the rate of growth in mathematics achievement during middle and high school. Graphical analysis showed that students who started middle school with higher achievement took individual mathematics…

  11. Autonomous beating rate adaptation in human stem cell-derived cardiomyocytes

    PubMed Central

    Eng, George; Lee, Benjamin W.; Protas, Lev; Gagliardi, Mark; Brown, Kristy; Kass, Robert S.; Keller, Gordon; Robinson, Richard B.; Vunjak-Novakovic, Gordana

    2016-01-01

    The therapeutic success of human stem cell-derived cardiomyocytes critically depends on their ability to respond to and integrate with the surrounding electromechanical environment. Currently, the immaturity of human cardiomyocytes derived from stem cells limits their utility for regenerative medicine and biological research. We hypothesize that biomimetic electrical signals regulate the intrinsic beating properties of cardiomyocytes. Here we show that electrical conditioning of human stem cell-derived cardiomyocytes in three-dimensional culture promotes cardiomyocyte maturation, alters their automaticity and enhances connexin expression. Cardiomyocytes adapt their autonomous beating rate to the frequency at which they were stimulated, an effect mediated by the emergence of a rapidly depolarizing cell population, and the expression of hERG. This rate-adaptive behaviour is long lasting and transferable to the surrounding cardiomyocytes. Thus, electrical conditioning may be used to promote cardiomyocyte maturation and establish their automaticity, with implications for cell-based reduction of arrhythmia during heart regeneration. PMID:26785135

  12. Proteolytic Processing Regulates Placental Growth Factor Activities*

    PubMed Central

    Hoffmann, Daniel C.; Willenborg, Sebastian; Koch, Manuel; Zwolanek, Daniela; Müller, Stefan; Becker, Ann-Kathrin A.; Metzger, Stephanie; Ehrbar, Martin; Kurschat, Peter; Hellmich, Martin; Hubbell, Jeffrey A.; Eming, Sabine A.

    2013-01-01

    Placental growth factor (PlGF) is a critical mediator of blood vessel formation, yet mechanisms of its action and regulation are incompletely understood. Here we demonstrate that proteolytic processing regulates the biological activity of PlGF. Specifically, we show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We have identified plasmin cleavage sites, generated a truncated PlGF118 isoform mimicking plasmin-processed PlGF, and explored its biological function in comparison with that of PlGF-1 and -2. The angiogenic responses induced by the diverse PlGF forms were distinct. Whereas PlGF-2 increased endothelial cell chemotaxis, vascular sprouting, and granulation tissue formation upon skin injury, these activities were abrogated following plasmin digestion. Investigation of PlGF/Neuropilin-1 binding and function suggests a critical role for heparin-binding domain/Neuropilin-1 interaction and its regulation by plasmin processing. Collectively, here we provide new mechanistic insights into the regulation of PlGF-2/Neuropilin-1-mediated tissue vascularization and growth. PMID:23645683

  13. Investigating mitochondrial metabolism in contracting HL-1 cardiomyocytes following hypoxia and pharmacological HIF activation identifies HIF-dependent and independent mechanisms of regulation.

    PubMed

    Ambrose, Lucy J A; Abd-Jamil, Amira H; Gomes, Renata S M; Carter, Emma E; Carr, Carolyn A; Clarke, Kieran; Heather, Lisa C

    2014-11-01

    Hypoxia is a consequence of cardiac disease and downregulates mitochondrial metabolism, yet the molecular mechanisms through which this occurs in the heart are incompletely characterized. Therefore, we aimed to use a contracting HL-1 cardiomyocyte model to investigate the effects of hypoxia on mitochondrial metabolism. Cells were exposed to hypoxia (2% O2) for 6, 12, 24, and 48 hours to characterize the metabolic response. Cells were subsequently treated with the hypoxia inducible factor (HIF)-activating compound, dimethyloxalylglycine (DMOG), to determine whether hypoxia-induced mitochondrial changes were HIF dependent or independent, and to assess the suitability of this cultured cardiac cell line for cardiovascular pharmacological studies. Hypoxic cells had increased glycolysis after 24 hours, with glucose transporter 1 and lactate levels increased 5-fold and 15-fold, respectively. After 24 hours of hypoxia, mitochondrial networks were more fragmented but there was no change in citrate synthase activity, indicating that mitochondrial content was unchanged. Cellular oxygen consumption was 30% lower, accompanied by decreases in the enzymatic activities of electron transport chain (ETC) complexes I and IV, and aconitase by 81%, 96%, and 72%, relative to controls. Pharmacological HIF activation with DMOG decreased cellular oxygen consumption by 43%, coincident with decreases in the activities of aconitase and complex I by 26% and 30%, indicating that these adaptations were HIF mediated. In contrast, the hypoxia-mediated decrease in complex IV activity was not replicated by DMOG treatment, suggesting HIF-independent regulation of this complex. In conclusion, 24 hours of hypoxia increased anaerobic glycolysis and decreased mitochondrial respiration, which was associated with changes in ETC and tricarboxylic acid cycle enzyme activities in contracting HL-1 cells. Pharmacological HIF activation in this cardiac cell line allowed both HIF-dependent and independent

  14. Underground tuning: quantitative regulation of root growth.

    PubMed

    Satbhai, Santosh B; Ristova, Daniela; Busch, Wolfgang

    2015-02-01

    Plants display a high degree of phenotypic plasticity that allows them to tune their form and function to changing environments. The plant root system has evolved mechanisms to anchor the plant and to efficiently explore soils to forage for soil resources. Key to this is an enormous capacity for plasticity of multiple traits that shape the distribution of roots in the soil. Such root system architecture-related traits are determined by root growth rates, root growth direction, and root branching. In this review, we describe how the root system is constituted, and which mechanisms, pathways, and genes mainly regulate plasticity of the root system in response to environmental variation.

  15. An integrated mechanism of cardiomyocyte nuclear Ca(2+) signaling.

    PubMed

    Ibarra, Cristián; Vicencio, Jose Miguel; Varas-Godoy, Manuel; Jaimovich, Enrique; Rothermel, Beverly A; Uhlén, Per; Hill, Joseph A; Lavandero, Sergio

    2014-10-01

    In cardiomyocytes, Ca(2+) plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca(2+) within subcellular microdomains: transcription is regulated by Ca(2+) release within nuclear microdomains, and excitation-contraction coupling is regulated by cytosolic Ca(2+). Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca(2+) signals. However, signaling pathways coupling surface receptor activation to nuclear Ca(2+) release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca(2+) signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca(2+) release from perinuclear Ca(2+) stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca(2+) release. In this review, we discuss mechanisms for the selective control of nuclear Ca(2+) signals with special focus on emerging models of agonist receptor activation.

  16. An integrated mechanism of cardiomyocyte nuclear Ca2+ signaling

    PubMed Central

    Ibarra, Cristián; Vicencio, Jose Miguel; Varas-Godoy, Manuel; Jaimovich, Enrique; Rothermel, Beverly A.; Uhlén, Per; Hill, Joseph A.; Lavandero, Sergio

    2015-01-01

    In cardiomyocytes, Ca2+ plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca2+ within subcellular microdomains: transcription is regulated by Ca2+ release within nuclear microdomains, and excitation–contraction coupling is regulated by cytosolic Ca2+. Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca2+ signals. However, signaling pathways coupling surface receptor activation to nuclear Ca2+ release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca2+ signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca2+ release from perinuclear Ca2+ stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca2+ release. In this review, we discuss mechanisms for the selective control of nuclear Ca2+ signals with special focus on emerging models of agonist receptor activation. PMID:24997440

  17. Compartmentalized energy transfer in cardiomyocytes: use of mathematical modeling for analysis of in vivo regulation of respiration.

    PubMed Central

    Aliev, M K; Saks, V A

    1997-01-01

    The mathematical model of the compartmentalized energy transfer system in cardiac myocytes presented includes mitochondrial synthesis of ATP by ATP synthase, phosphocreatine production in the coupled mitochondrial creatine kinase reaction, the myofibrillar and cytoplasmic creatine kinase reactions, ATP utilization by actomyosin ATPase during the contraction cycle, and diffusional exchange of metabolites between different compartments. The model was used to calculate the changes in metabolite profiles during the cardiac cycle, metabolite and energy fluxes in different cellular compartments at high workload (corresponding to the rate of oxygen consumption of 46 mu atoms of O.(g wet mass)-1.min-1) under varying conditions of restricted ADP diffusion across mitochondrial outer membrane and creatine kinase isoenzyme "switchoff." In the complete system, restricted diffusion of ADP across the outer mitochondrial membrane stabilizes phosphocreatine production in cardiac mitochondria and increases the role of the phosphocreatine shuttle in energy transport and respiration regulation. Selective inhibition of myoplasmic or mitochondrial creatine kinase (modeling the experiments with transgenic animals) results in "takeover" of their function by another, active creatine kinase isoenzyme. This mathematical modeling also shows that assumption of the creatine kinase equilibrium in the cell may only be a very rough approximation to the reality at increased workload. The mathematical model developed can be used as a basis for further quantitative analyses of energy fluxes in the cell and their regulation, particularly by adding modules for adenylate kinase, the glycolytic system, and other reactions of energy metabolism of the cell. Images FIGURE 7 FIGURE 2 FIGURE 7 PMID:9199806

  18. Unexpected maturation of PI3K and MAPK-ERK signaling in fetal ovine cardiomyocytes

    PubMed Central

    Louey, S.; Stork, P. J.; Giraud, G. D.; Thornburg, K. L.

    2014-01-01

    In the first two-thirds of gestation, ovine fetal cardiomyocytes undergo mitosis to increase cardiac mass and accommodate fetal growth. Thereafter, some myocytes continue to proliferate while others mature and terminally differentiate into binucleated cells. At term (145 days gestational age; dGA) about 60% of cardiomyocytes become binucleated and exit the cell cycle under hormonal control. Rising thyroid hormone (T3) levels near term (135 dGA) inhibit proliferation and stimulate maturation. However, the degree to which intracellular signaling patterns change with age in response to T3 is unknown. We hypothesized that in vitro activation of ERK, Akt, and p70S6K by two regulators of cardiomyocyte cell cycle activity, T3 and insulin like growth factor-1 (IGF-1), would be similar in cardiomyocytes at gestational ages 100 and 135 dGA. IGF-1 and T3 each independently stimulated phosphorylation of ERK, Akt, and p70S6K in cells at both ages. In the younger mononucleated myocytes, the phosphorylation of ERK and Akt was reduced in the presence of IGF-1 and T3. However, the same hormone combination led to a dramatic twofold increase in the phosphorylation of these signaling proteins in the 135 dGA cardiomyocytes—even in cells that were not proliferating. In the older cells, both mono- and binucleated cells were affected. In conclusion, fetal ovine cardiomyocytes undergo profound maturation-related changes in signaling in response to T3 and IGF-1, but not to either factor alone. Differences in age-related response are likely to be related to milestones in fetal cardiac development as the myocardium prepares for ex utero life. PMID:25128174

  19. MicroRNA-322 protects hypoxia-induced apoptosis in cardiomyocytes via BDNF gene

    PubMed Central

    Yang, Liguo; Song, Shigang; Lv, Hang

    2016-01-01

    Background: Cardiomyocytes apoptosis under hypoxia condition contributes significantly to various cardiovascular diseases. In this study, we investigated the role of microRNA-322 (miR-322) in regulating hypoxia-induced apoptosis in neonatal murine cardiomyocytes in vitro. Method: Cardiomyocytes of C57BL/6J mice were treated with hypoxia condition in vitro. Cardiomyocyte apoptosis was measured by TUNEL assay. Gene expression pattern of miR-322 was measured by qRT-PCR. Stable downregulation of miR-322 in cardiomyocytes were achieved by lentiviral transduction, and the effect of miR-322 downregulation on hypoxia-induced cardiomyocyte apoptosis was investigated. Possible regulation of miR-322 on its downstream target gene, brain derived neurotrophic factor (BDNF) was investigated in cardiomyocytes. BDNF was then genetically silenced by siRNA to evaluate its role in miR-137 mediated cardiomyocyte apoptosis protection under hypoxia condition. Results: Under hypoxia condition, significant apoptosis was induced and miR-322 was significantly upregulated in cardiomyocytes in vitro. Through lentiviral transduction, miR-322 was efficiently knocked down in cardiomyocytes. Downregulation of miR-322 protected hypoxia-induced cardiomyocyte apoptosis. Luciferase assay showed BDNF was the target gene of miR-322. QRT-PCR showed BDNF expression was associated with miR-322 regulation on hypoxia-induced cardiomyocyte apoptosis. Silencing BDNF in cardiomyocyte through siRNA transfection reversed the protective effect of miR-322 downregulation on hypoxia-induced apoptosis. Conclusion: Our study revealed that miR-322, in association with BDNF, played important role in regulating hypoxia-induced apoptosis in cardiomyocyte. PMID:27398164

  20. Regulation of body growth by microRNAs.

    PubMed

    Lui, Julian C

    2016-10-24

    Regulation of body growth remains a fascinating and unresolved biological mystery. One key component of body growth is skeletal and longitudinal bone growth. Children grow taller because their bones grew longer, and the predominant driver of longitudinal bone growth is a cartilaginous structure found near the ends of long bone named the growth plate. Numerous recent studies have started to unveil the importance of microRNAs in regulation of growth plate functions, therefore contributing to regulation of linear growth. In addition to longitudinal growth, other organs in our body need to increase in size and cell number as we grow, and the regulation of organ growth involves both systemic factors like hormones; and other intrinsic mechanisms, which we are just beginning to understand. This review aims to summarize some recent important findings on how microRNAs are involved in both of these processes: the regulation of longitudinal bone growth, and the regulation of organs and overall body growth.

  1. Regulation of myostatin activity and muscle growth.

    PubMed

    Lee, S J; McPherron, A C

    2001-07-31

    Myostatin is a transforming growth factor-beta family member that acts as a negative regulator of skeletal muscle mass. To identify possible myostatin inhibitors that may have applications for promoting muscle growth, we investigated the regulation of myostatin signaling. Myostatin protein purified from mammalian cells consisted of a noncovalently held complex of the N-terminal propeptide and a disulfide-linked dimer of C-terminal fragments. The purified C-terminal myostatin dimer was capable of binding the activin type II receptors, Act RIIB and, to a lesser extent, Act RIIA. Binding of myostatin to Act RIIB could be inhibited by the activin-binding protein follistatin and, at higher concentrations, by the myostatin propeptide. To determine the functional significance of these interactions in vivo, we generated transgenic mice expressing high levels of the propeptide, follistatin, or a dominant-negative form of Act RIIB by using a skeletal muscle-specific promoter. Independent transgenic mouse lines for each construct exhibited dramatic increases in muscle mass comparable to those seen in myostatin knockout mice. Our findings suggest that the propeptide, follistatin, or other molecules that block signaling through this pathway may be useful agents for enhancing muscle growth for both human therapeutic and agricultural applications.

  2. Brassinosteroids Regulate Root Growth, Development, and Symbiosis.

    PubMed

    Wei, Zhuoyun; Li, Jia

    2016-01-04

    Brassinosteroids (BRs) are natural plant hormones critical for growth and development. BR deficient or signaling mutants show significantly shortened root phenotypes. However, for a long time, it was thought that these phenotypes were solely caused by reduced cell elongation in the mutant roots. Functions of BRs in regulating root development have been largely neglected. Nonetheless, recent detailed analyses, revealed that BRs are not only involved in root cell elongation but are also involved in many aspects of root development, such as maintenance of meristem size, root hair formation, lateral root initiation, gravitropic response, mycorrhiza formation, and nodulation in legume species. In this review, current findings on the functions of BRs in mediating root growth, development, and symbiosis are discussed.

  3. Atorvastatin protects cardiomyocytes from oxidative stress by inhibiting LOX-1 expression and cardiomyocyte apoptosis.

    PubMed

    Zhang, Lei; Cheng, Linfang; Wang, Qiqi; Zhou, Dongchen; Wu, Zhigang; Shen, Ling; Zhang, Li; Zhu, Jianhua

    2015-03-01

    Coronary artery disease (CAD) is a major health problem worldwide. The most severe form of CAD is acute coronary syndrome (ACS). Recent studies have demonstrated the beneficial role of atorvastatin in ACS; however, the mechanisms underlying this effect have not been fully clarified. Growing evidence indicates that activation of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays an important role in oxidative stress-induced cardiomyocyte apoptosis during ACS. In this study, we examined whether atorvastatin inhibits H2O2-induced LOX-1 expression and H9c2 cardiomyocyte apoptosis, and investigated the underlying signaling pathway. Treatment of H9c2 cardiomyocytes with H2O2 resulted in elevated expression of LOX-1 mRNA and protein, as well as increased caspase-3 and -9 protein expression and cell apoptosis. H2O2-induced LOX-1 expression, caspase protein expression, and cardiomyocyte apoptosis were attenuated by pretreatment with atorvastatin. Atorvastatin activated H2O2-inhibited phosphorylation of Akt in a concentration-dependent manner. The Akt inhibitor, LY294002, inhibited the effect of atorvastatin on inducing Akt phosphorylation and on suppressing H2O2-mediated caspase up-regulation and cell apoptosis. These findings indicate that atorvastatin protects cardiomyocyte from oxidative stress via inhibition of LOX-1 expression and apoptosis, and that activation of H2O2-inhibited phosphorylation of Akt may play an important role in the protective function of atorvastatin.

  4. Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

    SciTech Connect

    Oyama, Kotaro; Mizuno, Akari; Shintani, Seine A.; Itoh, Hideki; Serizawa, Takahiro; Fukuda, Norio; Suzuki, Madoka

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Infra-red laser beam generates microscopic heat pulses. Black-Right-Pointing-Pointer Heat pulses induce contraction of cardiomyocytes. Black-Right-Pointing-Pointer Ca{sup 2+} transients during the contraction were not detected. Black-Right-Pointing-Pointer Skinned cardiomyocytes in free Ca{sup 2+} solution also contracted. Black-Right-Pointing-Pointer Heat pulses regulated the contractions without Ca{sup 2+} dynamics. -- Abstract: It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heat pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, {Delta}T, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, {Delta}T at physiological temperature was lower than that at room temperature. Ca{sup 2+} transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca{sup 2+} solution. This heat pulse-induced Ca{sup 2+}-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.

  5. Process for producing vegetative and tuber growth regulator

    NASA Technical Reports Server (NTRS)

    Stutte, Gary W. (Inventor); Yorio, Neil C. (Inventor)

    1999-01-01

    A process of making a vegetative and tuber growth regulator. The vegetative and tuber growth regulator is made by growing potato plants in a recirculating hydroponic system for a sufficient time to produce the growth regulator. Also, the use of the vegetative and growth regulator on solanaceous plants, tuber forming plants and ornamental seedlings by contacting the roots or shoots of the plant with a sufficient amount of the growth regulator to regulate the growth of the plant and one more of canopy size, plant height, stem length, internode number and presence of tubers in fresh mass. Finally, a method for regulating the growth of potato plants using a recirculating hydroponic system is described.

  6. Local IGF-1 isoform protects cardiomyocytes from hypertrophic and oxidative stresses via SirT1 activity.

    PubMed

    Vinciguerra, Manlio; Santini, Maria Paola; Claycomb, William C; Ladurner, Andreas G; Rosenthal, Nadia

    2009-12-10

    Oxidative and hypertrophic stresses contribute to the pathogenesis of heart failure. Insulin-like growth factor-1 (IGF-1) is a peptide hormone with a complex post-transcriptional regulation, generating distinct isoforms. Locally acting IGF-1 isoform (mIGF-1) helps the heart to recover from toxic injury and from infarct. In the murine heart, moderate overexpression of the NAD(+)-dependent deacetylase SirT1 was reported to mitigate oxidative stress. SirT1 is known to promote lifespan extension and to protect from metabolic challenges. Circulating IGF-1 and SirT1 play antagonizing biological roles and share molecular targets in the heart, in turn affecting cardiomyocyte physiology. However, how different IGF-1 isoforms may impact SirT1 and affect cardiomyocyte function is unknown. Here we show that locally acting mIGF-1 increases SirT1 expression/activity, whereas circulating IGF-1 isoform does not affect it, in cultured HL-1 and neonatal cardiomyocytes. mIGF-1-induced SirT1 activity exerts protection against angiotensin II (Ang II)-triggered hypertrophy and against paraquat (PQ) and Ang II-induced oxidative stress. Conversely, circulating IGF-1 triggered itself oxidative stress and cardiomyocyte hypertrophy. Interestingly, potent cardio-protective genes (adiponectin, UCP-1 and MT-2) were increased specifically in mIGF-1-overexpressing cardiomyocytes, in a SirT1-dependent fashion. Thus, mIGF-1 protects cardiomyocytes from oxidative and hypertrophic stresses via SirT1 activity, and may represent a promising cardiac therapeutic.

  7. Calcium and mitochondrial metabolism in ceramide-induced cardiomyocyte death

    PubMed Central

    Parra, Valentina; Moraga, Francisco; Kuzmicic, Jovan; López-Crisosto, Camila; Troncoso, Rodrigo; Torrealba, Natalia; Criollo, Alfredo; Díaz-Elizondo, Jessica; Rothermel, Beverly A.; Quest, Andrew F.G.; Lavandero, Sergio

    2014-01-01

    Ceramides are important intermediates in the biosynthesis and degradation of sphingolipids that regulatenumerous cellular processes, including cell cycle progression, cell growth, differentiation and death. In cardiomyocytes, ceramides induce apoptosis by decreasing mitochondrial membrane potential and promoting cytochrome-c release. Ca2+ overload is a common feature of all types of cell death. The aim of this study was to determine the effect of ceramides on cytoplasmic Ca2+ levels, mitochondrial function and cardiomyocyte death. Our data show that C2-ceramide induces apoptosis and necrosis in cultured cardiomyocytes by a mechanism involving increased Ca2+ influx, mitochondrial network fragmentation and loss of the mitochondrial Ca2+ buffer capacity. These biochemical events increase cytosolic Ca2+ levels and trigger cardiomyocyte death via the activation of calpains. PMID:23602992

  8. Building and re-building the heart by cardiomyocyte proliferation

    PubMed Central

    Foglia, Matthew J.; Poss, Kenneth D.

    2016-01-01

    The adult human heart does not regenerate significant amounts of lost tissue after injury. Rather than making new, functional muscle, human hearts are prone to scarring and hypertrophy, which can often lead to fatal arrhythmias and heart failure. The most-cited basis of this ineffective cardiac regeneration in mammals is the low proliferative capacity of adult cardiomyocytes. However, mammalian cardiomyocytes can avidly proliferate during fetal and neonatal development, and both adult zebrafish and neonatal mice can regenerate cardiac muscle after injury, suggesting that latent regenerative potential exists. Dissecting the cellular and molecular mechanisms that promote cardiomyocyte proliferation throughout life, deciphering why proliferative capacity normally dissipates in adult mammals, and deriving means to boost this capacity are primary goals in cardiovascular research. Here, we review our current understanding of how cardiomyocyte proliferation is regulated during heart development and regeneration. PMID:26932668

  9. Fibroblast Growth Factor Signaling in Metabolic Regulation

    PubMed Central

    Nies, Vera J. M.; Sancar, Gencer; Liu, Weilin; van Zutphen, Tim; Struik, Dicky; Yu, Ruth T.; Atkins, Annette R.; Evans, Ronald M.; Jonker, Johan W.; Downes, Michael Robert

    2016-01-01

    The prevalence of obesity is a growing health problem. Obesity is strongly associated with several comorbidities, such as non-alcoholic fatty liver disease, certain cancers, insulin resistance, and type 2 diabetes, which all reduce life expectancy and life quality. Several drugs have been put forward in order to treat these diseases, but many of them have detrimental side effects. The unexpected role of the family of fibroblast growth factors in the regulation of energy metabolism provides new approaches to the treatment of metabolic diseases and offers a valuable tool to gain more insight into metabolic regulation. The known beneficial effects of FGF19 and FGF21 on metabolism, together with recently discovered similar effects of FGF1 suggest that FGFs and their derivatives carry great potential as novel therapeutics to treat metabolic conditions. To facilitate the development of new therapies with improved targeting and minimal side effects, a better understanding of the molecular mechanism of action of FGFs is needed. In this review, we will discuss what is currently known about the physiological roles of FGF signaling in tissues important for metabolic homeostasis. In addition, we will discuss current concepts regarding their pharmacological properties and effector tissues in the context of metabolic disease. Also, the recent progress in the development of FGF variants will be reviewed. Our goal is to provide a comprehensive overview of the current concepts and consensuses regarding FGF signaling in metabolic health and disease and to provide starting points for the development of FGF-based therapies against metabolic conditions. PMID:26834701

  10. Myc overexpression enhances of epicardial contribution to the developing heart and promotes extensive expansion of the cardiomyocyte population

    PubMed Central

    Villa del Campo, Cristina; Lioux, Ghislaine; Carmona, Rita; Sierra, Rocío; Muñoz-Chápuli, Ramón; Clavería, Cristina; Torres, Miguel

    2016-01-01

    Myc is an essential regulator of cell growth and proliferation. Myc overexpression promotes the homeostatic expansion of cardiomyocyte populations by cell competition, however whether this applies to other cardiac lineages remains unknown. The epicardium contributes signals and cells to the developing and adult injured heart and exploring strategies for modulating its activity is of great interest. Using inducible genetic mosaics, we overexpressed Myc in the epicardium and determined the differential expansion of Myc-overexpressing cells with respect to their wild type counterparts. Myc-overexpressing cells overcolonized all epicardial-derived lineages and showed increased ability to invade the myocardium and populate the vasculature. We also found massive colonization of the myocardium by Wt1Cre-derived Myc-overexpressing cells, with preservation of cardiac development. Detailed analyses showed that this contribution is unlikely to derive from Cre activity in early cardiomyocytes but does not either derive from established epicardial cells, suggesting that early precursors expressing Wt1Cre originate the recombined cardiomyocytes. Myc overexpression does not modify the initial distribution of Wt1Cre-recombined cardiomyocytes, indicating that it does not stimulate the incorporation of early expressing Wt1Cre lineages to the myocardium, but differentially expands this initial population. We propose that strategies using epicardial lineages for heart repair may benefit from promoting cell competitive ability. PMID:27752085

  11. Regulation of Pollen Tube Growth by Transglutaminase

    PubMed Central

    Cai, Giampiero; Serafini-Fracassini, Donatella; Del Duca, Stefano

    2013-01-01

    In pollen tubes, cytoskeleton proteins are involved in many aspects of pollen germination and growth, from the transport of sperm cells to the asymmetrical distribution of organelles to the deposition of cell wall material. These activities are based on the dynamics of the cytoskeleton. Changes to both actin filaments and microtubules are triggered by specific proteins, resulting in different organization levels suitable for the different functions of the cytoskeleton. Transglutaminases are enzymes ubiquitous in all plant organs and cell compartments. They catalyze the post-translational conjugation of polyamines to different protein targets, such as the cytoskeleton. Transglutaminases are suggested to have a general role in the interaction between pollen tubes and the extracellular matrix during fertilization and a specific role during the self-incompatibility response. In such processes, the activity of transglutaminases is enhanced, leading to the formation of cross-linked products (including aggregates of tubulin and actin). Consequently, transglutaminases are suggested to act as regulators of cytoskeleton dynamics. The distribution of transglutaminases in pollen tubes is affected by both membrane dynamics and the cytoskeleton. Transglutaminases are also secreted in the extracellular matrix, where they may take part in the assembly and/or strengthening of the pollen tube cell wall. PMID:27137368

  12. Excitation–Contraction Coupling of the Mouse Embryonic Cardiomyocyte

    PubMed Central

    Rapila, Risto; Korhonen, Topi; Tavi, Pasi

    2008-01-01

    In the mammalian embryo, the primitive tubular heart starts beating during the first trimester of gestation. These early heartbeats originate from calcium-induced contractions of the developing heart muscle cells. To explain the initiation of this activity, two ideas have been presented. One hypothesis supports the role of spontaneously activated voltage-gated calcium channels, whereas the other emphasizes the role of Ca2+ release from intracellular stores initiating spontaneous intracellular calcium oscillations. We show with experiments that both of these mechanisms coexist and operate in mouse cardiomyocytes during embryonic days 9–11. Further, we characterize how inositol-3-phosphate receptors regulate the frequency of the sarcoplasmic reticulum calcium oscillations and thus the heartbeats. This study provides a novel view of the regulation of embryonic cardiomyocyte activity, explaining the functional versatility of developing cardiomyocytes and the origin and regulation of the embryonic heartbeat. PMID:18794377

  13. Excitation-contraction coupling of the mouse embryonic cardiomyocyte.

    PubMed

    Rapila, Risto; Korhonen, Topi; Tavi, Pasi

    2008-10-01

    In the mammalian embryo, the primitive tubular heart starts beating during the first trimester of gestation. These early heartbeats originate from calcium-induced contractions of the developing heart muscle cells. To explain the initiation of this activity, two ideas have been presented. One hypothesis supports the role of spontaneously activated voltage-gated calcium channels, whereas the other emphasizes the role of Ca(2+) release from intracellular stores initiating spontaneous intracellular calcium oscillations. We show with experiments that both of these mechanisms coexist and operate in mouse cardiomyocytes during embryonic days 9-11. Further, we characterize how inositol-3-phosphate receptors regulate the frequency of the sarcoplasmic reticulum calcium oscillations and thus the heartbeats. This study provides a novel view of the regulation of embryonic cardiomyocyte activity, explaining the functional versatility of developing cardiomyocytes and the origin and regulation of the embryonic heartbeat.

  14. 17(R),18(S)-Epoxyeicosatetraenoic Acid, A Potent Eicosapentaenoic Acid (EPA)-Derived Regulator of Cardiomyocyte Contraction: Structure-Activity Relationships and Stable Analogs

    PubMed Central

    Falck, John R.; Wallukat, Gerd; Puli, Narender; Goli, Mohan; Arnold, Cosima; Konkel, Anne; Rothe, Michael; Fischer, Robert; Müller, Dominik N.; Schunck, Wolf-Hagen

    2011-01-01

    17(R),18(S)-Epoxyeicosatetraenoic acid [17(R),18(S)-EETeTr], a cytochrome P450 epoxygenase metabolite of eicosapentaenoic acid (EPA), exerts negative chronotropic effects and protects neonatal rat cardiomyocytes against Ca2+-overload with an EC50 ~1–2 nM. Structure-activity studies revealed a cis-Δ11,12- or Δ14,15-olefin and a 17(R),18(S)-epoxide are minimal structural elements for anti-arrhythmic activity whereas antagonist activity was often associated with the combination of a Δ14,15-olefin and a 17(S),18(R)-epoxide. Compared with natural material, the agonist and antagonist analogs are chemically and metabolically more robust and several show promise as templates for future development of clinical candidates. PMID:21591683

  15. Disruption of Smad5 gene induces mitochondria-dependent apoptosis in cardiomyocytes

    SciTech Connect

    Sun Yanxun; Zhou Jiang; Liao Xudong; Lue Yaxin; Deng Chuxia; Huang Peitang; Chen Quan; Yang Xiao . E-mail: yangx@nic.bmi.ac.cn

    2005-05-15

    Our previous studies have shown that SMAD5, an important intracellular mediator of transforming growth factor {beta} (TGF-{beta}) family, is required for normal development of the cardiovascular system in vivo. In the current study, we reported that the lack of the Smad5 gene resulted in apoptosis of cardiac myocytes in vivo. To further investigate the mechanism of the Smad5 gene in cardiomyocyte apoptosis, the embryonic stem (ES) cell differentiation system was employed. We found that the myotubes that differentiated from the homozygous Smad5 {sup ex6/ex6} mutant ES cells underwent collapse and degeneration during the late stages of in vitro differentiation, mimicking the in vivo observation. By electron microscopy, abnormal swollen mitochondria were observed in cardiomyocytes both from Smad5-deficient embryos and from ES-differentiated cells. There was also a significant reduction in mitochondrial membrane potential ({delta}{psi} {sub m}) and a leakage of cytochrome c from mitochondria into the cytosol of myocytes differentiated from Smad5 mutant ES cells. The expression of p53 and p21 was found to be elevated in the differentiated Smad5 mutant myocytes, and this was accompanied by an up-regulation in caspase 3 expression. These results suggest that the Smad5-mediated TGF-{beta} signals may protect cardiomyocytes from apoptosis by maintaining the integrity of the mitochondria, probably through suppression of p53 mediated pathways.

  16. Mesenchymal Stem Cells and Cardiomyocytes Interplay to Prevent Myocardial Hypertrophy

    PubMed Central

    Tan, Xueying; Zhang, Yong; Li, Xingda; Wang, Xinyue; Zhu, Jiuxin; Wang, Yang; Yang, Fan; Wang, Baoqiu; Liu, Yanju; Xu, Chaoqian; Pan, Zhenwei; Wang, Ning; Yang, Baofeng

    2015-01-01

    Bone marrow-derived mesenchymal stem cells (BMSCs) have emerged as a promising therapeutic strategy for cardiovascular disease. However, there is no evidence so far that BMSCs can heal pathological myocardial hypertrophy. In this study, BMSCs were indirectly cocultured with neonatal rat ventricular cardiomyocytes (NRVCs) in vitro or intramyocardially transplanted into hypertrophic hearts in vivo. The results showed that isoproterenol (ISO)-induced typical hypertrophic characteristics of cardiomyocytes were prevented by BMSCs in the coculture model in vitro and after BMSC transplantation in vivo. Furthermore, activation of the Ca2+/calcineurin/nuclear factor of activated T cells cytoplasmic 3 (NFATc3) hypertrophic pathway in NRVCs was abrogated in the presence of BMSCs both in vitro and in vivo. Interestingly, inhibition of vascular endothelial growth factor (VEGF) release from BMSCs, but not basic fibroblast growth factor and insulin-like growth factor 1, abolished the protective effects of BMSCs on cardiomyocyte hypertrophy. Consistently, VEGF administration attenuated ISO-induced enlargement of cellular size; the upregulation of atrial natriuretic peptide, brain natriuretic peptide, and β-myosin heavy chain expression; and the activation of Ca2+/calcineurin/NFATc3 hypertrophic pathways, and these pathways can be abrogated by blocking VEGFR-1 in cardiomyocytes, indicating that VEGF receptor 1 is involved in the antihypertrophic role of VEGF. We further found that the ample VEGF secretion contributing to the antihypertrophic effects of BMSCs originates from the crosstalk of BMSCs and cardiac cells but not BMSCs or cardiomyocytes alone. Interplay of mesenchymal stem cells with cardiomyocytes produced synergistic effects on VEGF release. In summary, crosstalk between mesenchymal stem cells and cardiomyocytes contributes to the inhibition of myocardial hypertrophy via inhibiting Ca2+/calcineurin/NFATc3 hypertrophic pathways in cardiac cells. These results provide the

  17. Angiotensin II stimulates hyperplasia but not hypertrophy in immature ovine cardiomyocytes.

    PubMed

    Sundgren, N C; Giraud, G D; Stork, P J S; Maylie, J G; Thornburg, K L

    2003-05-01

    Rat and sheep cardiac myocytes become binucleate as they complete the 'terminal differentiation' process soon after birth and are not able to divide thereafter. Angiotensin II (Ang II) is known to stimulate hypertrophic changes in rodent cardiomyocytes under both in vivo and in vitro conditions via the AT1 receptor and intracellular extracellular regulated kinase (ERK) signalling cascade. We sought to develop culture methods for immature sheep cardiomyocytes in order to test the hypothesis that Ang II is a hypertrophic agent in the immature myocardium of the sheep. We isolated fetal sheep cardiomyocytes and cultured them for 96 h, added Ang II and phenylephrine (PE) for 48 h, and measured footprint area and proliferation (5-bromo-2'-deoxyuridine (BrdU) uptake) separately in mono- vs. binucleate myocytes. We found that neither Ang II nor PE changed the footprint area of mononucleated cells. PE stimulated an increase in footprint area of binucleate cells but Ang II did not. Ang II increased myocyte BrdU uptake compared to serum free conditions, but PE did not affect BrdU uptake. The MAP kinase kinase (MEK) inhibitor UO126 prevented BrdU uptake in Ang II-stimulated cells and prevented cell hypertrophy in PE-stimulated cells. This paper establishes culture methods for immature sheep cardiomyocytes and reports that: (1) Ang II is not a hypertrophic agent; (2) Ang II stimulates hyperplastic growth among mononucleate myocytes; (3) PE is a hypertrophic agent in binucleate myocytes; and (4) the ERK cascade is required for the proliferation effect of Ang II and the hypertrophic effect of PE.

  18. Angiotensin II stimulates hyperplasia but not hypertrophy in immature ovine cardiomyocytes

    PubMed Central

    Sundgren, N C; Giraud, G D; Stork, P J S; Maylie, J G; Thornburg, K L

    2003-01-01

    Rat and sheep cardiac myocytes become binucleate as they complete the ‘terminal differentiation’ process soon after birth and are not able to divide thereafter. Angiotensin II (Ang II) is known to stimulate hypertrophic changes in rodent cardiomyocytes under both in vivo and in vitro conditions via the AT1 receptor and intracellular extracellular regulated kinase (ERK) signalling cascade. We sought to develop culture methods for immature sheep cardiomyocytes in order to test the hypothesis that Ang II is a hypertrophic agent in the immature myocardium of the sheep. We isolated fetal sheep cardiomyocytes and cultured them for 96 h, added Ang II and phenylephrine (PE) for 48 h, and measured footprint area and proliferation (5-bromo-2′-deoxyuridine (BrdU) uptake) separately in mono- vs. binucleate myocytes. We found that neither Ang II nor PE changed the footprint area of mononucleated cells. PE stimulated an increase in footprint area of binucleate cells but Ang II did not. Ang II increased myocyte BrdU uptake compared to serum free conditions, but PE did not affect BrdU uptake. The MAP kinase kinase (MEK) inhibitor UO126 prevented BrdU uptake in Ang II-stimulated cells and prevented cell hypertrophy in PE-stimulated cells. This paper establishes culture methods for immature sheep cardiomyocytes and reports that: (1) Ang II is not a hypertrophic agent; (2) Ang II stimulates hyperplastic growth among mononucleate myocytes; (3) PE is a hypertrophic agent in binucleate myocytes; and (4) the ERK cascade is required for the proliferation effect of Ang II and the hypertrophic effect of PE. PMID:12626668

  19. Mechanochemical regulation of growth cone motility

    PubMed Central

    Kerstein, Patrick C.; Nichol, Robert H.; Gomez, Timothy M.

    2015-01-01

    Neuronal growth cones are exquisite sensory-motor machines capable of transducing features contacted in their local extracellular environment into guided process extension during development. Extensive research has shown that chemical ligands activate cell surface receptors on growth cones leading to intracellular signals that direct cytoskeletal changes. However, the environment also provides mechanical support for growth cone adhesion and traction forces that stabilize leading edge protrusions. Interestingly, recent work suggests that both the mechanical properties of the environment and mechanical forces generated within growth cones influence axon guidance. In this review we discuss novel molecular mechanisms involved in growth cone force production and detection, and speculate how these processes may be necessary for the development of proper neuronal morphogenesis. PMID:26217175

  20. β-Adrenergic response is counteracted by extremely-low-frequency pulsed electromagnetic fields in beating cardiomyocytes.

    PubMed

    Cornacchione, Marisa; Pellegrini, Manuela; Fassina, Lorenzo; Mognaschi, Maria Evelina; Di Siena, Sara; Gimmelli, Roberto; Ambrosino, Paolo; Soldovieri, Maria Virginia; Taglialatela, Maurizio; Gianfrilli, Daniele; Isidori, Andrea M; Lenzi, Andrea; Naro, Fabio

    2016-09-01

    Proper β-adrenergic signaling is indispensable for modulating heart frequency. Studies on extremely-low-frequency pulsed electromagnetic field (ELF-PEMF) effects in the heart beat function are contradictory and no definitive conclusions were obtained so far. To investigate the interplay between ELF-PEMF exposure and β-adrenergic signaling, cultures of primary murine neonatal cardiomyocytes and of sinoatrial node were exposed to ELF-PEMF and short and long-term effects were evaluated. The ELF-PEMF generated a variable magnetic induction field of 0-6mT at a frequency of 75Hz. Exposure to 3mT ELF-PEMF induced a decrease of contraction rate, Ca(2+) transients, contraction force, and energy consumption both under basal conditions and after β-adrenergic stimulation in neonatal cardiomyocytes. ELF-PEMF exposure inhibited β-adrenergic response in sinoatrial node (SAN) region. ELF-PEMF specifically modulated β2 adrenergic receptor response and the exposure did not modify the increase of contraction rate after adenylate cyclase stimulation by forskolin. In HEK293T cells transfected with β1 or β2 adrenergic receptors, ELF-PEMF exposure induced a rapid and selective internalization of β2 adrenergic receptor. The β-adrenergic signaling, was reduced trough Gi protein by ELF-PEMF exposure since the phosphorylation level of phospholamban and the PI3K pathway were impaired after isoproterenol stimulation in neonatal cardiomyocytes. Long term effects of ELF-PEMF exposure were assessed in cultures of isolated cardiomyocytes. ELF-PEMF counteracts cell size increase, the generation of binucleated of cardiomyocytes and prevents the up-regulation of hypertrophic markers after β-adrenergic stimulation, indicating an inhibition of cell growth and maturation. These data show that short and long term exposure to ELF-PEMF induces a reduction of cardiac β-adrenergic response at molecular, functional and adaptative levels.

  1. Epigenomic Reprogramming of Adult Cardiomyocyte-Derived Cardiac Progenitor Cells

    PubMed Central

    Zhang, Yiqiang; Zhong, Jiang F; Qiu, Hongyu; Robb MacLellan, W.; Marbán, Eduardo; Wang, Charles

    2015-01-01

    It has been believed that mammalian adult cardiomyocytes (ACMs) are terminally-differentiated and are unable to proliferate. Recently, using a bi-transgenic ACM fate mapping mouse model and an in vitro culture system, we demonstrated that adult mouse cardiomyocytes were able to dedifferentiate into cardiac progenitor-like cells (CPCs). However, little is known about the molecular basis of their intrinsic cellular plasticity. Here we integrate single-cell transcriptome and whole-genome DNA methylation analyses to unravel the molecular mechanisms underlying the dedifferentiation and cell cycle reentry of mouse ACMs. Compared to parental cardiomyocytes, dedifferentiated mouse cardiomyocyte-derived CPCs (mCPCs) display epigenomic reprogramming with many differentially-methylated regions, both hypermethylated and hypomethylated, across the entire genome. Correlated well with the methylome, our transcriptomic data showed that the genes encoding cardiac structure and function proteins are remarkably down-regulated in mCPCs, while those for cell cycle, proliferation, and stemness are significantly up-regulated. In addition, implantation of mCPCs into infarcted mouse myocardium improves cardiac function with augmented left ventricular ejection fraction. Our study demonstrates that the cellular plasticity of mammalian cardiomyocytes is the result of a well-orchestrated epigenomic reprogramming and a subsequent global transcriptomic alteration. PMID:26657817

  2. S100A8/MYD88/NF-қB: a novel pathway involved in cardiomyocyte hypertrophy driven by thyroid hormone.

    PubMed

    Takano, Ana Paula Cremasco; Munhoz, Carolina Demarchi; Moriscot, Anselmo Sigari; Gupta, Sudhiranjan; Barreto-Chaves, Maria Luiza Morais

    2017-02-04

    Recent studies have evidenced the involvement of inflammation-related pathways to the development of cardiac hypertrophy and other consequences on the cardiovascular system, including the calcium-binding protein S100A8. However, this has never been investigated in the thyroid hormone (TH)-prompted cardiac hypertrophy. Thus, we aimed to test whether S100A8 and related signaling molecules, myeloid differentiation factor-88 (MyD88) and nuclear factor kappa B (NF-қB), could be associated with the cardiomyocyte hypertrophy induced by TH. Our results demonstrate that the S100A8/MyD88/NF-қB signaling pathway is activated in cardiomyocytes following TH stimulation. The knockdown of S100A8 and MyD88 indicates the contribution of those molecules to cardiomyocyte hypertrophy in response to TH, as evaluated by cell surface area, leucine incorporation assay, and gene expression. Furthermore, S100A8 and MyD88 are crucial mediators of NF-қB activation, which is also involved in the hypertrophic growth of TH-treated cardiomyocytes. Supporting the in vitro data, the contribution of NF-қB for TH-induced cardiac hypertrophy is confirmed in vivo, by using transgenic mice with cardiomyocyte-specific suppression of NF-қB. These data identify a novel pathway regulated by TH that mediates cardiomyocyte hypertrophy. However, the potential role of this new pathway in short and long-term cardiac effects of TH remains to be further investigated.

  3. The regulation of plant growth by the circadian clock.

    PubMed

    Farré, E M

    2012-05-01

    Circadian regulated changes in growth rates have been observed in numerous plants as well as in unicellular and multicellular algae. The circadian clock regulates a multitude of factors that affect growth in plants, such as water and carbon availability and light and hormone signalling pathways. The combination of high-resolution growth rate analyses with mutant and biochemical analysis is helping us elucidate the time-dependent interactions between these factors and discover the molecular mechanisms involved. At the molecular level, growth in plants is modulated through a complex regulatory network, in which the circadian clock acts at multiple levels.

  4. Profilin modulates sarcomeric organization and mediates cardiomyocyte hypertrophy

    PubMed Central

    Kooij, Viola; Viswanathan, Meera C.; Lee, Dong I.; Rainer, Peter P.; Schmidt, William; Kronert, William A.; Harding, Sian E.; Kass, David A.; Bernstein, Sanford I.; Van Eyk, Jennifer E.; Cammarato, Anthony

    2016-01-01

    Aims Heart failure is often preceded by cardiac hypertrophy, which is characterized by increased cell size, altered protein abundance, and actin cytoskeletal reorganization. Profilin is a well-conserved, ubiquitously expressed, multifunctional actin-binding protein, and its role in cardiomyocytes is largely unknown. Given its involvement in vascular hypertrophy, we aimed to test the hypothesis that profilin-1 is a key mediator of cardiomyocyte-specific hypertrophic remodelling. Methods and results Profilin-1 was elevated in multiple mouse models of hypertrophy, and a cardiomyocyte-specific increase of profilin in Drosophila resulted in significantly larger heart tube dimensions. Moreover, adenovirus-mediated overexpression of profilin-1 in neonatal rat ventricular myocytes (NRVMs) induced a hypertrophic response, measured by increased myocyte size and gene expression. Profilin-1 silencing suppressed the response in NRVMs stimulated with phenylephrine or endothelin-1. Mechanistically, we found that profilin-1 regulates hypertrophy, in part, through activation of the ERK1/2 signalling cascade. Confocal microscopy showed that profilin localized to the Z-line of Drosophila myofibrils under normal conditions and accumulated near the M-line when overexpressed. Elevated profilin levels resulted in elongated sarcomeres, myofibrillar disorganization, and sarcomeric disarray, which correlated with impaired muscle function. Conclusion Our results identify novel roles for profilin as an important mediator of cardiomyocyte hypertrophy. We show that overexpression of profilin is sufficient to induce cardiomyocyte hypertrophy and sarcomeric remodelling, and silencing of profilin attenuates the hypertrophic response. PMID:26956799

  5. Intra-Myocardial Injection of Both Growth Factors and Heart Derived Sca-1+/CD31− Cells Attenuates Post-MI LV Remodeling More Than Does Cell Transplantation Alone: Neither Intervention Enhances Functionally Significant Cardiomyocyte Regeneration

    PubMed Central

    Wang, Xiaohong; Li, Qinglu; Hu, Qingsong; Suntharalingam, Piradeep; From, Arthur H. L.; Zhang, Jianyi

    2014-01-01

    Insulin-like growth factor 1 (IGF-1) and hepatocyte growth factor (HGF) are two potent cell survival and regenerative factors in response to myocardial injury (MI). We hypothesized that simultaneous delivery of IGF+HGF combined with Sca-1+/CD31− cells would improve the outcome of transplantation therapy in response to the altered hostile microenvironment post MI. One million adenovirus nuclear LacZ-labeled Sca-1+/CD31− cells were injected into the peri-infarction area after left anterior descending coronary artery (LAD) ligation in mice. Recombinant mouse IGF-1+HGF was added to the cell suspension prior to the injection. The left ventricular (LV) function was assessed by echocardiography 4 weeks after the transplantation. The cell engraftment, differentiation and cardiomyocyte regeneration were evaluated by histological analysis. Sca-1+/CD31− cells formed viable grafts and improved LV ejection fraction (EF) (Control, 54.5+/−2.4; MI, 17.6+/−3.1; Cell, 28.2+/−4.2, n = 9, P<0.01). IGF+HGF significantly enhanced the benefits of cell transplantation as evidenced by increased EF (38.8+/−2.2; n = 9, P<0.01) and attenuated adverse structural remodeling. Furthermore, IGF+HGF supplementation increased the cell engraftment rate, promoted the transplanted cell survival, enhanced angiogenesis, and minimally stimulated endogenous cardiomyocyte regeneration in vivo. The in vitro experiments showed that IGF+HGF treatment stimulated Sca-1+/CD31− cell proliferation and inhibited serum free medium induced apoptosis. Supperarray profiling of Sca-1+/CD31− cells revealed that Sca-1+/CD31− cells highly expressed various trophic factor mRNAs and IGF+HGF treatment altered the mRNAs expression patterns of these cells. These data indicate that IGF-1+HGF could serve as an adjuvant to cell transplantation for myocardial repair by stimulating donor cell and endogenous cardiac stem cell survival, regeneration and promoting angiogenesis. PMID:24919180

  6. Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Auxinic herbicides, such as 2,4-D and dicamba, that act as plant growth regulators are commonly used for broadleaf weed control in cereal crops (e.g. wheat, barley), grasslands, and non-croplands. If applied at later growth stages, while cereals are developing reproductive parts, the herbicides can...

  7. Pro-survival function of MEF2 in cardiomyocytes is enhanced by β-blockers

    PubMed Central

    Hashemi, S; Salma, J; Wales, S; McDermott, JC

    2015-01-01

    β1-Adrenergic receptor (β1-AR) stimulation increases apoptosis in cardiomyocytes through activation of cAMP/protein kinase A (PKA) signaling. The myocyte enhancer factor 2 (MEF2) proteins function as important regulators of myocardial gene expression. Previously, we reported that PKA signaling directly represses MEF2 activity. We determined whether (a) MEF2 has a pro-survival function in cardiomyocytes, and (b) whether β-adrenergic/PKA signaling modulates MEF2 function in cardiomyocytes. Initially, we observed that siRNA-mediated gene silencing of MEF2 induces cardiomyocyte apoptosis as indicated by flow cytometry. β1-AR activation by isoproterenol represses MEF2 activity and promotes apoptosis in cultured neonatal cardiomyocytes. Importantly, β1-AR mediated apoptosis was abrogated in cardiomyocytes expressing a PKA-resistant form of MEF2D (S121/190A). We also observed that a β1-blocker, Atenolol, antagonizes isoproterenol-induced apoptosis while concomitantly enhancing MEF2 transcriptional activity. β-AR stimulation modulated MEF2 cellular localization in cardiomyocytes and this effect was reversed by β-blocker treatment. Furthermore, Kruppel-like factor 6, a MEF2 target gene in the heart, functions as a downstream pro-survival factor in cardiomyocytes. Collectively, these data indicate that (a) MEF2 has an important pro-survival role in cardiomyocytes, and (b) β-adrenergic signaling antagonizes the pro-survival function of MEF2 in cardiomyocytes and β-blockers promote it. These observations have important clinical implications that may contribute to novel strategies for preventing cardiomyocyte apoptosis associated with heart pathology. PMID:27551452

  8. Mechanical regulation of plant growth and development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.

    1984-01-01

    Soybean and eggplant grown and shaken in a greenhouse exhibited decreased internode length, internode diameter, leaf area, and fresh and dry weight of roots and shoots in much the same way as outdoor-exposed plants. Perhaps more important than decreased dimensions of plant parts resulting from periodic seismic treatment is the inhibition of photosynthetic productivity that accompanies this stress. Soybeam plants briefly shaken or rubbed twice daily experienced a decrease in relative as well as absolute growth rate compared to that of undisturbed controls. Growth dynamics analysis revealed that virtually all of the decline in relative growth rate (RGR) was due to a decline in net assimilation rate (NAR), but not in leaf area ratio (LAR). Lower NAR suggests that the stress-induced decrease in dry weight gain is due to a decline in photosynthetic efficiency. Possible effects on stomatal aperture was investigated by measuring rates of whole plant transpiration as a function of seismo-stress, and a transitory decrease followed by a gradual, partial recovery was detected.

  9. Role of endogenous PDGF-BB in cultured cardiomyocytes exposed to hypoxia.

    PubMed

    Rong, Rong; Wang, You-Cui; Hu, Li-qun; He, Qin-qin; Zhou, Xin-Fu; Wang, Ting-hua; Bu, Pei-li

    2015-04-01

    Platelet-derived growth factor-BB (PDGF-BB) plays a critical role in cell proliferation, angiogenesis and fibrosis. However, its exact role in cardiomyocytes exposed to hypoxia is not well known. This study was therefore designed to detect whether PDGF-BB expression was changed in a hypoxic condition, then the possible role of endogenous PDGF-BB in cardiomyocytes was explored, with interference RNA in a lentiviral vector ex vivo. The results showed that cultured cardiomyocytes exhibited an optimal proliferation from 3 to 10 days. However, LDH level was significantly increased but the heart rhythm was not altered in cardiomyocytes exposed to hypoxia for 24 hours. PDGF-BB expression was substantially upregulated in hypoxic cardiomyocytes. In order to know the role of PDGF-BB, we performed PDGF-BB knockdown in cultured cardiomyocytes. The number of apoptotic cells and the level of LDH were significantly increased but the beat rhythm was reduced in cardiomyocytes with PDGF-BB knockdown. These findings suggest that endogenous PDGF-BB exerts a crucial protective effect to cultured cardiomyocytes exposed to hypoxia.

  10. Importance of Thickness in Human Cardiomyocyte Network for Effective Electrophysiological Stimulation Using On-Chip Extracellular Microelectrodes

    NASA Astrophysics Data System (ADS)

    Hamada, Tomoyo; Nomura, Fumimasa; Kaneko, Tomoyuki; Yasuda, Kenji

    2012-06-01

    We have developed a three-dimensionally controlled in vitro human cardiomyocyte network assay for the measurements of drug-induced conductivity changes and the appearance of fatal arrhythmia such as ventricular tachycardia/fibrillation for more precise in vitro predictive cardiotoxicity. To construct an artificial conductance propagation model of a human cardiomyocyte network, first, we examined the cell concentration dependence of the cell network heights and found the existence of a height limit of cell networks, which was double-layer height, whereas the cardiomyocytes were effectively and homogeneously cultivated within the microchamber maintaining their spatial distribution constant and their electrophysiological conductance and propagation were successfully recorded using a microelectrode array set on the bottom of the microchamber. The pacing ability of a cardiomyocyte's electrophysiological response has been evaluated using microelectrode extracellular stimulation, and the stimulation for pacing also successfully regulated the beating frequencies of two-layered cardiomyocyte networks, whereas monolayered cardiomyocyte networks were hardly stimulated by the external electrodes using the two-layered cardiomyocyte stimulation condition. The stability of the lined-up shape of human cardiomyocytes within the rectangularly arranged agarose microchambers was limited for a two-layered cardiomyocyte network because their stronger force generation shrunk those cells after peeling off the substrate. The results indicate the importance of fabrication technology of thickness control of cellular networks for effective extracellular stimulation and the potential concerning thick cardiomyocyte networks for long-term cultivation.

  11. Postnatal telomere dysfunction induces cardiomyocyte cell-cycle arrest through p21 activation

    PubMed Central

    Aix, Esther; Gutiérrez-Gutiérrez, Óscar; Sánchez-Ferrer, Carlota; Aguado, Tania

    2016-01-01

    The molecular mechanisms that drive mammalian cardiomyocytes out of the cell cycle soon after birth remain largely unknown. Here, we identify telomere dysfunction as a critical physiological signal for cardiomyocyte cell-cycle arrest. We show that telomerase activity and cardiomyocyte telomere length decrease sharply in wild-type mouse hearts after birth, resulting in cardiomyocytes with dysfunctional telomeres and anaphase bridges and positive for the cell-cycle arrest protein p21. We further show that premature telomere dysfunction pushes cardiomyocytes out of the cell cycle. Cardiomyocytes from telomerase-deficient mice with dysfunctional telomeres (G3 Terc−/−) show precocious development of anaphase-bridge formation, p21 up-regulation, and binucleation. In line with these findings, the cardiomyocyte proliferative response after cardiac injury was lost in G3 Terc−/− newborns but rescued in G3 Terc−/−/p21−/− mice. These results reveal telomere dysfunction as a crucial signal for cardiomyocyte cell-cycle arrest after birth and suggest interventions to augment the regeneration capacity of mammalian hearts. PMID:27241915

  12. Regulation of plant growth by cytokinin

    PubMed Central

    Werner, Tomáš; Motyka, Václav; Strnad, Miroslav; Schmülling, Thomas

    2001-01-01

    Cytokinins are a class of plant-specific hormones that play a central role during the cell cycle and influence numerous developmental programs. Because of the lack of biosynthetic and signaling mutants, the regulatory roles of cytokinins are not well understood. We genetically engineered cytokinin oxidase expression in transgenic tobacco plants to reduce their endogenous cytokinin content. Cytokinin-deficient plants developed stunted shoots with smaller apical meristems. The plastochrone was prolonged, and leaf cell production was only 3–4% that of wild type, indicating an absolute requirement of cytokinins for leaf growth. In contrast, root meristems of transgenic plants were enlarged and gave rise to faster growing and more branched roots. These results suggest that cytokinins are an important regulatory factor of plant meristem activity and morphogenesis, with opposing roles in shoots and roots. PMID:11504909

  13. Muscle RING finger-1 attenuates IGF-I-dependent cardiomyocyte hypertrophy by inhibiting JNK signaling.

    PubMed

    Wadosky, Kristine M; Rodríguez, Jessica E; Hite, Rebecca L; Min, Jin-na; Walton, Bethany L; Willis, Monte S

    2014-04-01

    Recent studies implicate the muscle-specific ubiquitin ligase muscle RING finger-1 (MuRF1) in inhibiting pathological cardiomyocyte growth in vivo by inhibiting the transcription factor SRF. These studies led us to hypothesize that MuRF1 similarly inhibits insulin-like growth factor-I (IGF-I)-mediated physiological cardiomyocyte growth. We identified two lines of evidence to support this hypothesis: IGF-I stimulation of cardiac-derived cells with MuRF1 knockdown 1) exhibited an exaggerated hypertrophy and, 2) conversely, increased MuRF1 expression-abolished IGF-I-dependent cardiomyocyte growth. Enhanced hypertrophy with MuRF1 knockdown was accompanied by increases in Akt-regulated gene expression. Unexpectedly, MuRF1 inhibition of this gene expression profile was not a result of differences in p-Akt. Instead, we found that MuRF1 inhibits total protein levels of Akt, GSK-3β (downstream of Akt), and mTOR while limiting c-Jun protein expression, a mechanism recently shown to govern Akt, GSK-3β, and mTOR activities and expression. These findings establish that MuRF1 inhibits IGF-I signaling by restricting c-Jun activity, a novel mechanism recently identified in the context of ischemia-reperfusion injury. Since IGF-I regulates exercise-mediated physiological cardiac growth, we challenged MuRF1(-/-) and MuRF1-Tg+ mice and their wild-type sibling controls to 5 wk of voluntary wheel running. MuRF1(-/-) cardiac growth was increased significantly over wild-type control; conversely, the enhanced exercise-induced cardiac growth was lost in MuRF1-Tg+ animals. These studies demonstrate that MuRF1-dependent attenuation of IGF-I signaling via c-Jun is applicable in vivo and establish that further understanding of this novel mechanism may be crucial in the development of therapies targeting IGF-I signaling.

  14. The neglected role of insulin-like growth factors in the maternal circulation regulating fetal growth.

    PubMed

    Sferruzzi-Perri, A N; Owens, J A; Pringle, K G; Roberts, C T

    2011-01-01

    Maternal insulin-like growth factors (IGFs) play a pivotal role in modulating fetal growth via their actions on both the mother and the placenta. Circulating IGFs influence maternal tissue growth and metabolism, thereby regulating nutrient availability for the growth of the conceptus. Maternal IGFs also regulate placental morphogenesis, substrate transport and hormone secretion, all of which influence fetal growth either via indirect effects on maternal substrate availability, or through direct effects on the placenta and its capacity to supply nutrients to the fetus. The extent to which IGFs influence the mother and/or placenta are dependent on the species and maternal factors, including age and nutrition. As altered fetal growth is associated with increased perinatal morbidity and mortality and a greater risk of developing degenerative diseases in adult life, understanding the role of maternal IGFs during pregnancy is essential in order to identify mechanisms underlying altered fetal growth and offspring programming.

  15. Recent research on the growth plate: Recent insights into the regulation of the growth plate.

    PubMed

    Lui, Julian C; Nilsson, Ola; Baron, Jeffrey

    2014-08-01

    For most bones, elongation is driven primarily by chondrogenesis at the growth plates. This process results from chondrocyte proliferation, hypertrophy, and extracellular matrix secretion, and it is carefully orchestrated by complex networks of local paracrine factors and modulated by endocrine factors. We review here recent advances in the understanding of growth plate physiology. These advances include new approaches to study expression patterns of large numbers of genes in the growth plate, using microdissection followed by microarray. This approach has been combined with genome-wide association studies to provide insights into the regulation of the human growth plate. We also review recent studies elucidating the roles of bone morphogenetic proteins, fibroblast growth factors, C-type natriuretic peptide, and suppressor of cytokine signaling in the local regulation of growth plate chondrogenesis and longitudinal bone growth.

  16. Catecholamines promote Actinobacillus pleuropneumoniae growth by regulating iron metabolism.

    PubMed

    Li, Lu; Chen, Zhaohui; Bei, Weicheng; Su, Zhipeng; Huang, Qi; Zhang, Liang; Chen, Huanchun; Zhou, Rui

    2015-01-01

    Catecholamines are host stress hormones that can induce the growth of many bacteria by facilitating iron utilization and/or regulate the expression of virulence genes through specific hormone receptors. Whether these two responsive pathways are interconnected is unknown. In our previous study, it was found that catecholamines can regulate the expression of a great number of genes of Actinobacillus pleuropneumoniae, an important swine respiratory pathogen. However, bacterial growth was not affected by catecholamines in rich medium. In this study, it was discovered that catecholamines affected A. pleuropneumoniae growth in chemically defined medium (CDM). We found that serum inhibited A. pleuropneumoniae growth in CDM, while epinephrine, norepinephrine and dopamine promoted A. pleuropneumoniae growth in the CDM containing serum. The known bacterial hormone receptor QseC didn't play roles in this process. Ion-supplementation and transcriptome analysis indicated that serum addition resulted in iron-restricted conditions which were alleviated by the addition of catecholamines. Transferrin, one of the components in serum, inhibited the growth of A. pleuropneumoniae in CDM, an effect reversed by addition of catecholamines in a TonB2-dependent manner. Our data demonstrate that catecholamines promote A. pleuropneumoniae growth by regulating iron-acquisition and metabolism, which is independent of the adrenergic receptor QseC.

  17. Comparison of the hypertrophic effect of phorbol ester, norepinephrine, angiotensin II and contraction on cultured cardiomyocytes

    SciTech Connect

    Allo, S.N.; Carl, L.L.; Morgan, H.E. )

    1991-03-15

    Phorbol 12-myristate 13-acetate (PMA), norepinephrine (NE), angiotensin II (AII) and contraction stimulate cardiomyocyte growth. Differences exist in the time course and extent of protein and RNA accumulation. Cells plated at 4 {times} 10{sup 6} cells/60mm dish and arrested with 50 mM KCl demonstrated no significant growth. Treatment with PMA stimulated growth to a maximum of 17% at 48 h. In contrast, maximal stimulation of growth was 36% at 48 h and 31% at 72 h for contracting and NE treated cells, respectively. Maximal stimulation of the capacity for protein synthesis was 32% for PMA treated cells at 24 h as compared to 59% and 77% for NE treated and contracting cells respectively at 72 h. In support of a primary role for altered capacity in the regulation of protein synthesis, there was a significant correlation between RNA and protein content independent of the stimulus used. AII increased RNA content by 28% at 48h, but had no effect on growth up to 72h. Treatment with staurosporine blocked the stimulation of growth, suggestive of a role for protein kinase C (PKC). However, the inhibition of contraction-induced growth was due in part to a reduction in the rate of contraction. It was concluded that: significant differences existed in the time course of growth stimulation and RNA accumulation, depending on the stimulus; and growth inhibition by staurosporine is suggestive of an important role of PKC in hypertrophic growth induced by these stimuli.

  18. The Growth Hormone Secretagogue Receptor: Its Intracellular Signaling and Regulation

    PubMed Central

    Yin, Yue; Li, Yin; Zhang, Weizhen

    2014-01-01

    The growth hormone secretagogue receptor (GHSR), also known as the ghrelin receptor, is involved in mediating a wide variety of biological effects of ghrelin, including: stimulation of growth hormone release, increase of food intake and body weight, modulation of glucose and lipid metabolism, regulation of gastrointestinal motility and secretion, protection of neuronal and cardiovascular cells, and regulation of immune function. Dependent on the tissues and cells, activation of GHSR may trigger a diversity of signaling mechanisms and subsequent distinct physiological responses. Distinct regulation of GHSR occurs at levels of transcription, receptor interaction and internalization. Here we review the current understanding on the intracellular signaling pathways of GHSR and its modulation. An overview of the molecular structure of GHSR is presented first, followed by the discussion on its signaling mechanisms. Finally, potential mechanisms regulating GHSR are reviewed. PMID:24651458

  19. The role of mAKAPβ in the process of cardiomyocyte hypertrophy induced by angiotensin II.

    PubMed

    Guo, Huixin; Liu, Baoxin; Hou, Lei; The, Erlinda; Li, Gang; Wang, Dongzhi; Jie, Qiqiang; Che, Wenliang; Wei, Yidong

    2015-05-01

    Angiotensin II (AngII) is the central product of the renin-angiotensin system (RAS) and this octapeptide contributes to the pathophysiology of cardiac hypertrophy and remodeling. mAKAPβ is an A-kinase anchoring protein (AKAP) that has the function of binding to the regulatory subunit of protein kinase A (PKA) and confining the holoenzyme to discrete locations within the cell. In this study, we aimed to investigate the role of mAKAPβ in AngII‑induced cardiomyocyte hypertrophy and the possible mechanisms involved. Cultured cardiomyocytes from neonatal rats were treated with AngII. Subsequently, the morphology of the cardiomyocytes was observed and the expression of mAKAPβ and cardiomyocyte hypertrophic markers was measured. mAKAPβ‑shRNA was constructed for RNA interference; the expression of mAKAPβ and hypertrophic markers, the cell surface area and the [3H]Leucine incorporation rate in the AngII‑treated rat cardiomyocytes were detected following RNA interference. Simultaneously, changes in the expression levels of phosphorylated extracellular signal-regulated kinase (p-ERK)2 in the cardiomyocytes were assessed. The cell size of the AngII-treated cardiaomyocytes was significantly larger than that of the untreated cardiomyocytes. The expression of hypertrophic markers and p-ERK2, the cell surface area and the [3H]Leucine incorporation rate were all significantly increased in the AngII‑treated cells. However, the expression of mAKAPβ remained unaltered in this process. RNA interference simultaneously inhibited the protein expression of mAKAPβ and p‑ERK2, and the hypertrophy of the cardiomyocytes induced by AngII was attenuated. These results demonstrate that AngII induces hypertrophy in cardiomyocytes, and mAKAPβ is possibly involved in this process. The effects of mAKAPβ on AngII‑induced cardiomyocyte hypertrophy may be associated with p-ERK2 expression.

  20. Cardiomyocyte-secreted acetylcholine is required for maintenance of homeostasis in the heart

    PubMed Central

    Roy, Ashbeel; Fields, William C.; Rocha-Resende, Cibele; Resende, Rodrigo R.; Guatimosim, Silvia; Prado, Vania F.; Gros, Robert; Prado, Marco A. M.

    2013-01-01

    Heart activity and long-term function are regulated by the sympathetic and parasympathetic branches of the nervous system. Parasympathetic neurons have received increased attention recently because acetylcholine (ACh) has been shown to play protective roles in heart disease. However, parasympathetic innervation is sparse in the heart, raising the question of how cholinergic signaling regulates cardiomyocytes. We hypothesized that non-neuronal secretion of ACh from cardiomyocytes plays a role in cholinergic regulation of cardiac activity. To test this possibility, we eliminated secretion of ACh exclusively from cardiomyocytes by targeting the vesicular acetylcholine transporter (VAChT). We find that lack of cardiomyocyte-secreted ACh disturbs the regulation of cardiac activity and causes cardiomyocyte remodeling. Mutant mice present normal hemodynamic parameters under nonstressful conditions; however, following exercise, their heart rate response is increased. Moreover, hearts from mutant mice present increased oxidative stress, altered calcium signaling, remodeling, and hypertrophy. Hence, without cardiomyocyte-derived ACh secretion, hearts from mutant mice show signs of imbalanced autonomic activity consistent with decreased cholinergic drive. These unexpected results suggest that cardiomyocyte-derived ACh is required for maintenance of cardiac homeostasis and regulates critical signaling pathways necessary to maintain normal heart activity. We propose that this non-neuronal source of ACh boosts parasympathetic cholinergic signaling to counterbalance sympathetic activity regulating multiple aspects of heart physiology.—Roy, A., Fields, W. C., Rocha-Resende, C., Resende, R. R., Guatimosim, S., Prado, V. F., Gros, R., Prado, M. A. M. Cardiomyocyte-secreted acetylcholine is required for maintenance of homeostasis in the heart. PMID:24018063

  1. Glucose induces apoptosis of cardiomyocytes via microRNA-1 and IGF-1.

    PubMed

    Yu, Xi-Yong; Song, Yao-Hua; Geng, Yong-Jian; Lin, Qiu-Xiong; Shan, Zhi-Xin; Lin, Shu-Guang; Li, Yangxin

    2008-11-21

    Glucose toxicity is an important initiator of cardiovascular disease, contributing to the development of cardiomyocyte death and diabetic complications. The present study investigated whether high glucose state could induce apoptosis of rat cardiomyocyte cell line H9C2 through microRNA regulated insulin-like growth factor (IGF-1) signaling pathway. Our data showed that H9C2 cells exposed to high glucose have increased miR-1 expression level, decreased mitochondrial membrane potential, increased cytochrome-c release, and increased apoptosis. Glucose induced mitochondrial dysfunction, cytochrome-c release and apoptosis was blocked by IGF-1. Using prediction algorithms, we identified 3'-untranslated regions of IGF-1 gene are the target of miR-1. miR-1 mimics, but not mutant miR-1, blocked the capacity of IGF-1 to prevent glucose-induced mitochondrial dysfunction, cytochrome-c release and apoptosis. In conclusion, our data demonstrate that IGF-1 inhibits glucose-induced mitochondrial dysfunction, cytochrome-c release and apoptosis and IGF-1's effect is regulated by miR-1.

  2. Local translation of RhoA regulates growth cone collapse

    PubMed Central

    Cox, Llewellyn J.; Macosko, Evan Z.; Jeromin, Andreas; Urquhart, Erica R.; Jaffrey, Samie R.

    2005-01-01

    Neuronal development requires highly coordinated regulation of the cytoskeleton within the developing axon. This dynamic regulation manifests itself in axonal branching, turning, and pathfinding, presynaptic differentiation, and growth cone collapse and extension. Semaphorin 3A (Sema3A), a secreted guidance cue that primarily acts to repel axons from inappropriate targets, induces cytoskeletal rearrangements that results in growth cone collapse 1. These effects require intra-axonal mRNA translation. Here we show that transcripts for RhoA, a small GTPase that regulates the actin cytoskeleton, are localized to developing axons and growth cones, and this localization is mediated by an axonal targeting element located in the RhoA 3’UTR. Sema3A induces intra-axonal translation of RhoA mRNA and this local translation of RhoA is necessary and sufficient for Sema3A-mediated growth cone collapse. These studies indicate that local RhoA translation regulates the neuronal cytoskeleton and identify a novel mechanism for the regulation of RhoA signaling. PMID:16107849

  3. Insulin signaling regulates neurite growth during metamorphic neuronal remodeling

    PubMed Central

    Gu, Tingting; Zhao, Tao; Hewes, Randall S.

    2014-01-01

    Summary Although the growth capacity of mature neurons is often limited, some neurons can shift through largely unknown mechanisms from stable maintenance growth to dynamic, organizational growth (e.g. to repair injury, or during development transitions). During insect metamorphosis, many terminally differentiated larval neurons undergo extensive remodeling, involving elimination of larval neurites and outgrowth and elaboration of adult-specific projections. Here, we show in the fruit fly, Drosophila melanogaster (Meigen), that a metamorphosis-specific increase in insulin signaling promotes neuronal growth and axon branching after prolonged stability during the larval stages. FOXO, a negative effector in the insulin signaling pathway, blocked metamorphic growth of peptidergic neurons that secrete the neuropeptides CCAP and bursicon. RNA interference and CCAP/bursicon cell-targeted expression of dominant-negative constructs for other components of the insulin signaling pathway (InR, Pi3K92E, Akt1, S6K) also partially suppressed the growth of the CCAP/bursicon neuron somata and neurite arbor. In contrast, expression of wild-type or constitutively active forms of InR, Pi3K92E, Akt1, Rheb, and TOR, as well as RNA interference for negative regulators of insulin signaling (PTEN, FOXO), stimulated overgrowth. Interestingly, InR displayed little effect on larval CCAP/bursicon neuron growth, in contrast to its strong effects during metamorphosis. Manipulations of insulin signaling in many other peptidergic neurons revealed generalized growth stimulation during metamorphosis, but not during larval development. These findings reveal a fundamental shift in growth control mechanisms when mature, differentiated neurons enter a new phase of organizational growth. Moreover, they highlight strong evolutionarily conservation of insulin signaling in neuronal growth regulation. PMID:24357229

  4. Substrate and nutrient limitation regulating microbial growth in soil

    NASA Astrophysics Data System (ADS)

    Bååth, Erland

    2015-04-01

    Microbial activity and growth in soil is regulated by several abiotic factors, including temperature, moisture and pH as the most important ones. At the same time nutrient conditions and substrate availability will also determine microbial growth. Amount of substrate will not only affect overall microbial growth, but also affect the balance of fungal and bacterial growth. The type of substrate will also affect the latter. Furthermore, according to Liebig law of limiting factors, we would expect one nutrient to be the main limiting one for microbial growth in soil. When this nutrient is added, the initial second liming factor will become the main one, adding complexity to the microbial response after adding different substrates. I will initially describe different ways of determining limiting factors for bacterial growth in soil, especially a rapid method estimating bacterial growth, using the leucine incorporation technique, after adding C (as glucose), N (as ammonium nitrate) and P (as phosphate). Scenarios of different limitations will be covered, with the bacterial growth response compared with fungal growth and total activity (respiration). The "degree of limitation", as well as the main limiting nutrient, can be altered by adding substrate of different stoichiometric composition. However, the organism group responding after alleviating the nutrient limitation can differ depending on the type of substrate added. There will also be situations, where fungi and bacteria appear to be limited by different nutrients. Finally, I will describe interactions between abiotic factors and the response of the soil microbiota to alleviation of limiting factors.

  5. Cyp26b1 within the growth plate regulates bone growth in juvenile mice

    SciTech Connect

    Minegishi, Yoshiki; Sakai, Yasuo; Yahara, Yasuhito; Akiyama, Haruhiko; Yoshikawa, Hideki; Hosokawa, Ko; Tsumaki, Noriyuki

    2014-11-07

    Highlights: • Retinoic acid and Cyp26b1 were oppositely localized in growth plate cartilage. • Cyp26b1 deletion in chondrocytes decreased bone growth in juvenile mice. • Cyp26b1 deletion reduced chondrocyte proliferation and growth plate height. • Vitamin A-depletion partially reversed growth plate abnormalities caused by Cyp26b1 deficiency. • Cyp26b1 regulates bone growth by controlling chondrocyte proliferation. - Abstract: Retinoic acid (RA) is an active metabolite of vitamin A and plays important roles in embryonic development. CYP26 enzymes degrade RA and have specific expression patterns that produce a RA gradient, which regulates the patterning of various structures in the embryo. However, it has not been addressed whether a RA gradient also exists and functions in organs after birth. We found localized RA activities in the diaphyseal portion of the growth plate cartilage were associated with the specific expression of Cyp26b1 in the epiphyseal portion in juvenile mice. To disturb the distribution of RA, we generated mice lacking Cyp26b1 specifically in chondrocytes (Cyp26b1{sup Δchon} cKO). These mice showed reduced skeletal growth in the juvenile stage. Additionally, their growth plate cartilage showed decreased proliferation rates of proliferative chondrocytes, which was associated with a reduced height in the zone of proliferative chondrocytes, and closed focally by four weeks of age, while wild-type mouse growth plates never closed. Feeding the Cyp26b1 cKO mice a vitamin A-deficient diet partially reversed these abnormalities of the growth plate cartilage. These results collectively suggest that Cyp26b1 in the growth plate regulates the proliferation rates of chondrocytes and is responsible for the normal function of the growth plate and growing bones in juvenile mice, probably by limiting the RA distribution in the growth plate proliferating zone.

  6. Heparin localization and fine structure regulate Burkitt's lymphoma growth

    SciTech Connect

    Berry, David; Lynn, David M.; Berry, Eric; Sasisekharan, Ram; Langer, Robert . E-mail: rlanger@mit.edu

    2006-09-29

    Burkitt's lymphoma (BL) is a B-cell malignancy associated with the Epstein-Barr virus (EBV). Mounting evidence has implicated heparan sulfate proteoglycans and heparan sulfate-like glycosaminoglycans (HSGAGs) in the initiation, severity, and progression of the malignancy. The importance of HSGAGs in regulating BL cell growth was therefore examined. Extracellular exogenous heparin inhibited cell growth >30%, while heparin internalized with poly({beta}-amino ester)s promoted proliferation up to 58%. The growth-modulating effects of heparin and internalized heparin were dependent on cell surface HSGAGs, PI3K, and Erk/Mek. Treatment of cells with protamine sulfate or with heparinases potently inhibited proliferation, with the greatest effects induced by heparinase I. Cell surface HSGAGs therefore play an important role in regulating BL proliferation and may offer a potential target for therapeutic intervention.

  7. HMGCR positively regulated the growth and migration of glioblastoma cells.

    PubMed

    Qiu, Zhihua; Yuan, Wen; Chen, Tao; Zhou, Chenzhi; Liu, Chao; Huang, Yongkai; Han, Deqing; Huang, Qinghui

    2016-01-15

    The metabolic program of cancer cells is significant different from the normal cells, which makes it possible to develop novel strategies targeting cancer cells. Mevalonate pathway and its rate-limiting enzyme HMG-CoA reductase (HMGCR) have shown important roles in the progression of several cancer types. However, their roles in glioblastoma cells remain unknown. In this study, up-regulation of HMGCR in the clinical glioblastoma samples was observed. Forced expression of HMGCR promoted the growth and migration of U251 and U373 cells, while knocking down the expression of HMGCR inhibited the growth, migration and metastasis of glioblastoma cells. Molecular mechanism studies revealed that HMGCR positively regulated the expression of TAZ, an important mediator of Hippo pathway, and the downstream target gene connective tissue growth factor (CTGF), suggesting HMGCR might activate Hippo pathway in glioblastoma cells. Taken together, our study demonstrated the oncogenic roles of HMGCR in glioblastoma cells and HMGCR might be a promising therapeutic target.

  8. Microtopographical effects of natural scaffolding on cardiomyocyte function and arrhythmogenesis.

    PubMed

    Shah, U; Bien, H; Entcheva, E

    2010-08-01

    A natural myocardial patch for heart regeneration derived from porcine urinary bladder matrix (UBM) was previously reported to outperform synthetic materials (Dacron and expanded polytetrafluoroethylene (ePTFE)) used in current surgical treatments. UBM, an extracellular matrix prepared from urinary bladder, has intricate three-dimensional architecture with two distinct sides: the luminal side with a smoother surface relief; and the abluminal side with a fine mesh of nano- and microfibers. This study tested the ability of this natural scaffold to support functional cardiomyocyte networks, and probed how the local microtopography and composition of the two sides affects cell function. Cardiomyocytes isolated from neonatal rats were seeded in vitro to form cardiac tissue onto luminal (L) or abluminal (Ab) UBM. Immunocytochemistry of contractile cardiac proteins demonstrated growth of cardiomyocyte networks with mature morphology on either side of UBM, but greater cell compactness was seen in L. Fluorescence-based imaging techniques were used to measure dynamic changes in intracellular calcium concentration upon electrical stimulation of L and Ab-grown cells. Functional differences in cardiac tissue grown on the two sides manifested themselves in faster calcium recovery (p<0.04) and greater hysteresis (difference in response to increasing and decreasing pacing rates) for L vs Ab side (p<0.03). These results suggest that surface differences may be leveraged to engineer the desired cardiomyocyte responses and highlight the potential of natural scaffolds for fostering heart repair.

  9. Role of heterotrimeric G protein and calcium in cardiomyocyte hypertrophy induced by IGF-1.

    PubMed

    Carrasco, Loreto; Cea, Paola; Rocco, Paola; Peña-Oyarzún, Daniel; Rivera-Mejias, Pablo; Sotomayor-Flores, Cristian; Quiroga, Clara; Criollo, Alfredo; Ibarra, Cristian; Chiong, Mario; Lavandero, Sergio

    2014-04-01

    In the heart, insulin-like growth factor-1 (IGF-1) is a peptide with pro-hypertrophic and anti-apoptotic actions. The pro-hypertrophic properties of IGF-1 have been attributed to the extracellular regulated kinase (ERK) pathway. Recently, we reported that IGF-1 also increases intracellular Ca(2+) levels through a pertussis toxin (PTX)-sensitive G protein. Here we investigate whether this Ca(2+) signal is involved in IGF-1-induced cardiomyocyte hypertrophy. Our results show that the IGF-1-induced increase in Ca(2+) level is abolished by the IGF-1 receptor tyrosine kinase inhibitor AG538, PTX and the peptide inhibitor of Gβγ signaling, βARKct. Increases in the activities of Ca(2+) -dependent enzymes calcineurin, calmodulin kinase II (CaMKII), and protein kinase Cα (PKCα) were observed at 5 min after IGF-1 exposure. AG538, PTX, βARKct, and the dominant negative PKCα prevented the IGF-1-dependent phosphorylation of ERK1/2. Participation of calcineurin and CaMKII in ERK phosphorylation was discounted. IGF-1-induced cardiomyocyte hypertrophy, determined by cell size and β-myosin heavy chain (β-MHC), was prevented by AG538, PTX, βARKct, dominant negative PKCα, and the MEK1/2 inhibitor PD98059. Inhibition of calcineurin with CAIN did not abolish IGF-1-induced cardiac hypertrophy. We conclude that IGF-1 induces hypertrophy in cultured cardiomyocytes by activation of the receptor tyrosine kinase activity/βγ-subunits of a PTX-sensitive G protein/Ca(2+) /PKCα/ERK pathway without the participation of calcineurin.

  10. Local calcium changes regulate the length of growth cone filopodia.

    PubMed

    Cheng, Su; Geddis, Matthew S; Rehder, Vincent

    2002-03-01

    Previous studies have demonstrated that the free intracellular calcium concentration ([Ca(2+)](i)) in growth cones can act as an important regulator of growth cone behavior. Here we investigated whether there is a spatial and temporal correlation between [Ca(2+)](i) and one particular aspect of growth cone behavior, namely the regulation of growth cone filopodia. Calcium was released from the caged compound NP-EGTA (o-nitrophenyl EGTA tetrapotassium salt) to simulate a signaling event in the form of a transient increase in [Ca(2+)](i). In three different experimental paradigms, we released calcium either globally (within an entire growth cone), regionally (within a small area of the lamellipodium), or locally (within a single filopodium). We demonstrate that global photolysis of NP-EGTA in growth cones caused a transient increase in [Ca(2+)](i) throughout the growth cone and elicited subsequent filopodial elongation that was restricted to the stimulated growth cone. Pharmacological blockage of either calmodulin or the Ca(2+)-dependent phosphatase, calcineurin, inhibited the effect of uncaging calcium, suggesting that these enzymes are acting downstream of calcium. Regional uncaging of calcium in the lamellipodium caused a regional increase in [Ca(2+)](i), but induced filopodial elongation on the entire growth cone. Elevation of [Ca(2+)](i) locally within an individual filopodium resulted in the elongation of only the stimulated filopodium. These findings suggest that the effect of an elevation of [Ca(2+)](i) on filopodial behavior depends on the spatial distribution of the calcium signal. In particular, calcium signals within filopodia can cause filopodial length changes that are likely a first step towards directed filopodial steering events seen during pathfinding in vivo.

  11. Effects of Substrate Mechanics on Contractility of Cardiomyocytes Generated from Human Pluripotent Stem Cells

    PubMed Central

    Hazeltine, Laurie B.; Simmons, Chelsey S.; Salick, Max R.; Lian, Xiaojun; Badur, Mehmet G.; Han, Wenqing; Delgado, Stephanie M.; Wakatsuki, Tetsuro; Crone, Wendy C.; Pruitt, Beth L.; Palecek, Sean P.

    2012-01-01

    Human pluripotent stem cell (hPSC-) derived cardiomyocytes have potential applications in drug discovery, toxicity testing, developmental studies, and regenerative medicine. Before these cells can be reliably utilized, characterization of their functionality is required to establish their similarity to native cardiomyocytes. We tracked fluorescent beads embedded in 4.4–99.7 kPa polyacrylamide hydrogels beneath contracting neonatal rat cardiomyocytes and cardiomyocytes generated from hPSCs via growth-factor-induced directed differentiation to measure contractile output in response to changes in substrate mechanics. Contraction stress was determined using traction force microscopy, and morphology was characterized by immunocytochemistry for α-actinin and subsequent image analysis. We found that contraction stress of all types of cardiomyocytes increased with substrate stiffness. This effect was not linked to beating rate or morphology. We demonstrated that hPSC-derived cardiomyocyte contractility responded appropriately to isoprenaline and remained stable in culture over a period of 2 months. This study demonstrates that hPSC-derived cardiomyocytes have appropriate functional responses to substrate stiffness and to a pharmaceutical agent, which motivates their use in further applications such as drug evaluation and cardiac therapies. PMID:22649451

  12. Smad4 regulates growth plate matrix production and chondrocyte polarity

    PubMed Central

    Whitaker, Amanda T.; Berthet, Ellora; Cantu, Andrea; Laird, Diana J.

    2017-01-01

    ABSTRACT Smad4 is an intracellular effector of the TGFβ family that has been implicated in Myhre syndrome, a skeletal dysplasia characterized by short stature, brachydactyly and stiff joints. The TGFβ pathway also plays a critical role in the development, organization and proliferation of the growth plate, although the exact mechanisms remain unclear. Skeletal phenotypes in Myhre syndrome overlap with processes regulated by the TGFβ pathway, including organization and proliferation of the growth plate and polarity of the chondrocyte. We used in vitro and in vivo models of Smad4 deficiency in chondrocytes to test the hypothesis that deregulated TGFβ signaling leads to aberrant extracellular matrix production and loss of chondrocyte polarity. Specifically, we evaluated growth plate chondrocyte polarity in tibiae of Col2-Cre+/−;Smad4fl/fl mice and in chondrocyte pellet cultures. In vitro and in vivo, Smad4 deficiency decreased aggrecan expression and increased MMP13 expression. Smad4 deficiency disrupted the balance of cartilage matrix synthesis and degradation, even though the sequential expression of growth plate chondrocyte markers was intact. Chondrocytes in Smad4-deficient growth plates also showed evidence of polarity defects, with impaired proliferation and ability to undergo the characteristic changes in shape, size and orientation as they differentiated from resting to hypertrophic chondrocytes. Therefore, we show that Smad4 controls chondrocyte proliferation, orientation, and hypertrophy and is important in regulating the extracellular matrix composition of the growth plate. PMID:28167493

  13. Excitation model of pacemaker cardiomyocytes of cardiac conduction system

    NASA Astrophysics Data System (ADS)

    Grigoriev, M.; Babich, L.

    2015-11-01

    Myocardium includes typical and atypical cardiomyocytes - pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation - heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system.

  14. Alendronate affects calcium dynamics in cardiomyocytes in vitro.

    PubMed

    Kemeny-Suss, Naomi; Kasneci, Amanda; Rivas, Daniel; Afilalo, Jonathan; Komarova, Svetlana V; Chalifour, Lorraine E; Duque, Gustavo

    2009-01-01

    Therapy with bisphosphonates, including alendronate (ALN), is considered a safe and effective treatment for osteoporosis. However, recent studies have reported an unexpected increase in serious atrial fibrillation (AF) in patients treated with bisphosphonates. The mechanism that explains this side effect remains unknown. Since AF is associated with an altered sarcoendoplasmic reticulum calcium load, we studied how ALN affects cardiomyocyte calcium homeostasis and protein isoprenylation in vitro. Acute and long-term (48h) treatment of atrial and ventricular cardiomyocytes with ALN (10(-8)-10(-6)M) was performed. Changes in calcium dynamics were determined by both fluorescence measurement of cytosolic free Ca(2+) concentration and western blot analysis of calcium-regulating proteins. Finally, effect of ALN on protein farnesylation was also identified. In both atrial and ventricular cardiomyocytes, ALN treatment delayed and diminished calcium responses to caffeine. Only in atrial cells, long-term exposure to ALN-induced transitory calcium oscillations and led to the development of oscillatory component in calcium responses to caffeine. Changes in calcium dynamics were accompanied by changes in expression of proteins controlling sarcoendoplasmic reticulum calcium. In contrast, ALN minimally affected protein isoprenylation in these cells. In summary, treatment of atrial cardiomyocytes with ALN-induced abnormalities in calcium dynamics consistent with induction of a self-stimulatory, pacemaker-like behavior, which may contribute to the development of cardiac side effects associated with these drugs.

  15. Ethylene signaling and regulation in plant growth and stress responses.

    PubMed

    Wang, Feifei; Cui, Xiankui; Sun, Yue; Dong, Chun-Hai

    2013-07-01

    Gaseous phytohormone ethylene affects many aspects of plant growth and development. The ethylene signaling pathway starts when ethylene binds to its receptors. Since the cloning of the first ethylene receptor ETR1 from Arabidopsis, a large number of studies have steadily improved our understanding of the receptors and downstream components in ethylene signal transduction pathway. This article reviews the regulation of ethylene receptors, signal transduction, and the posttranscriptional modulation of downstream components. Functional roles and importance of the ethylene signaling components in plant growth and stress responses are also discussed. Cross-reactions of ethylene with auxin and other phytohormones in plant organ growth will be analyzed. The studies of ethylene signaling in plant growth, development, and stress responses in the past decade greatly advanced our knowledge of how plants respond to endogenous signals and environmental factors.

  16. Netrin-4 regulates angiogenic responses and tumor cell growth

    SciTech Connect

    Nacht, Mariana; St Martin, Thia B.; Byrne, Ann; Klinger, Katherine W.; Teicher, Beverly A.; Madden, Stephen L. Jiang, Yide

    2009-03-10

    Netrin-4 is a 628 amino acid basement membrane component that promotes neurite elongation at low concentrations but inhibits neurite extension at high concentrations. There is a growing body of literature suggesting that several molecules, including netrins, are regulators of both neuronal and vascular growth. It is believed that molecules that guide neural growth and development are also involved in regulating morphogenesis of the vascular tree. Further, netrins have recently been implicated in controlling epithelial cell branching morphogenesis in the breast, lung and pancreas. Characterization of purified netrin-4 in in vitro angiogenesis assays demonstrated that netrin-4 markedly inhibits HMVEC migration and tube formation. Moreover, netrin-4 inhibits proliferation of a variety of human tumor cells in vitro. Netrin-4 has only modest effects on proliferation of endothelial and other non-transformed cells. Netrin-4 treatment results in phosphorylation changes of proteins that are known to control cell growth. Specifically, Phospho-Akt-1, Phospho-Jnk-2, and Phospho-c-Jun are reduced in tumor cells that have been treated with netrin-4. Together, these data suggest a potential role for netrin-4 in regulating tumor growth.

  17. Bacterial gene regulation in diauxic and non-diauxic growth.

    PubMed

    Narang, Atul; Pilyugin, Sergei S

    2007-01-21

    When bacteria are grown in a batch culture containing a mixture of two growth-limiting substrates, they exhibit a rich spectrum of substrate consumption patterns including diauxic growth, simultaneous consumption, and bistable growth. In previous work, we showed that a minimal model accounting only for enzyme induction and dilution captures all the substrate consumption patterns [Narang, A., 1998a. The dynamical analogy between microbial growth on mixtures of substrates and population growth of competing species. Biotechnol. Bioeng. 59, 116-121, Narang, A., 2006. Comparitive analysis of some models of gene regulation in mixed-substrate microbial growth, J. Theor. Biol. 242, 489-501]. In this work, we construct the bifurcation diagram of the minimal model, which shows the substrate consumption pattern at any given set of parameter values. The bifurcation diagram explains several general properties of mixed-substrate growth. (1) In almost all the cases of diauxic growth, the "preferred" substrate is the one that, by itself, supports a higher specific growth rate. In the literature, this property is often attributed to the optimality of regulatory mechanisms. Here, we show that the minimal model, which accounts for induction and growth only, displays the property under fairly general conditions. This suggests that the higher growth rate of the preferred substrate is an intrinsic property of the induction and dilution kinetics. It can be explained mechanistically without appealing to optimality principles. (2) The model explains the phenotypes of various mutants containing lesions in the regions encoding for the operator, repressor, and peripheral enzymes. A particularly striking phenotype is the "reversal of the diauxie" in which the wild-type and mutant strains consume the very same two substrates in opposite order. This phenotype is difficult to explain in terms of molecular mechanisms, such as inducer exclusion or CAP activation, but it turns out to be a natural

  18. Maternal growth factor regulation of human placental development and fetal growth.

    PubMed

    Forbes, Karen; Westwood, Melissa

    2010-10-01

    Normal development and function of the placenta is critical to achieving a successful pregnancy, as normal fetal growth depends directly on the transfer of nutrients from mother to fetus via this organ. Recently, it has become apparent from both animal and human studies that growth factors within the maternal circulation, for example the IGFs, are important regulators of placental development and function. Although these factors act via distinct receptors to exert their effects, the downstream molecules activated upon ligand/receptor interaction are common to many growth factors. The expression of numerous signaling molecules is altered in the placentas from pregnancies affected by the fetal growth complications, fetal growth restriction, and macrosomia. Thus, targeting these molecules may lead to more effective treatments for complications of pregnancy associated with altered placental development. Here, we review the maternal growth factors required for placental development and discuss their mechanism of action.

  19. Understanding greater cardiomyocyte functions on aligned compared to random carbon nanofibers in PLGA.

    PubMed

    Asiri, Abdullah M; Marwani, Hadi M; Khan, Sher Bahadar; Webster, Thomas J

    2015-01-01

    Previous studies have demonstrated greater cardiomyocyte density on carbon nanofibers (CNFs) aligned (compared to randomly oriented) in poly(lactic-co-glycolic acid) (PLGA) composites. Although such studies demonstrated a closer mimicking of anisotropic electrical and mechanical properties for such aligned (compared to randomly oriented) CNFs in PLGA composites, the objective of the present in vitro study was to elucidate a deeper mechanistic understanding of how cardiomyocyte densities recognize such materials to respond more favorably. Results showed lower wettability (greater hydrophobicity) of CNFs embedded in PLGA compared to pure PLGA, thus providing evidence of selectively lower wettability in aligned CNF regions. Furthermore, the results correlated these changes in hydrophobicity with increased adsorption of fibronectin, laminin, and vitronectin (all proteins known to increase cardiomyocyte adhesion and functions) on CNFs in PLGA compared to pure PLGA, thus providing evidence of selective initial protein adsorption cues on such CNF regions to promote cardiomyocyte adhesion and growth. Lastly, results of the present in vitro study further confirmed increased cardiomyocyte functions by demonstrating greater expression of important cardiomyocyte biomarkers (such as Troponin-T, Connexin-43, and α-sarcomeric actin) when CNFs were aligned compared to randomly oriented in PLGA. In summary, this study provided evidence that cardiomyocyte functions are improved on CNFs aligned in PLGA compared to randomly oriented in PLGA since CNFs are more hydrophobic than PLGA and attract the adsorption of key proteins (fibronectin, laminin, and vironectin) that are known to promote cardiomyocyte adhesion and expression of important cardiomyocyte functions. Thus, future studies should use this knowledge to further design improved CNF:PLGA composites for numerous cardiovascular applications.

  20. Plant growth regulators enhance gold uptake in Brassica juncea.

    PubMed

    Kulkarni, Manoj G; Stirk, Wendy A; Southway, Colin; Papenfus, Heino B; Swart, Pierre A; Lux, Alexander; Vaculík, Marek; Martinka, Michal; Van Staden, Johannes

    2013-01-01

    The use of plant growth regulators is well established and they are used in many fields of plant science for enhancing growth. Brassica juncea plants were treated with 2.5, 5.0 and 7.5 microM auxin indole-3-butyric acid (IBA), which promotes rooting. The IBA-treated plants were also sprayed with 100 microM gibberellic acid (GA3) and kinetin (Kin) to increase leaf-foliage. Gold (I) chloride (AuCl) was added to the growth medium of plants to achieve required gold concentration. The solubilizing agent ammonium thiocyanate (1 g kg(-1)) (commonly used in mining industries to solubilize gold) was added to the nutrient solution after six weeks of growth and, two weeks later, plants were harvested. Plant growth regulators improved shoot and root dry biomass of B. juncea plants. Inductively Coupled Plasma Optical Emission Spectrometry analysis showed the highest Au uptake for plants treated with 5.0 microM IBA. The average recovery of Au with this treatment was significantly greater than the control treatment by 45.8 mg kg(-1) (155.7%). The other IBA concentrations (2.5 and 7.5 microM) also showed a significant increase in Au uptake compared to the control plants by 14.7 mg kg(-1) (50%) and 42.5 mg kg(-1) (144.5%) respectively. A similar trend of Au accumulation was recorded in the roots of B. juncea plants. This study conducted in solution culture suggests that plant growth regulators can play a significant role in improving phytoextraction of Au.

  1. Interactions between fibroblast growth factors and Notch regulate neuronal differentiation.

    PubMed

    Faux, C H; Turnley, A M; Epa, R; Cappai, R; Bartlett, P F

    2001-08-01

    The differentiation of precursor cells into neurons has been shown to be influenced by both the Notch signaling pathway and growth factor stimulation. In this study, the regulation of neuronal differentiation by these mechanisms was examined in the embryonic day 10 neuroepithelial precursor (NEP) population. By downregulating Notch1 expression and by the addition of a Delta1 fusion protein (Delta Fc), it was shown that signaling via the Notch pathway inhibited neuron differentiation in the NEP cells, in vitro. The expression of two of the Notch receptor homologs, Notch1 and Notch3, and the ligand Delta1 in these NEP cells was found to be influenced by a number of different growth factors, indicating a potential interaction between growth factors and Notch signaling. Interestingly, none of the growth factors examined promoted neuron differentiation; however, the fibroblast growth factors (FGFs) 1 and 2 potently inhibited differentiation. FGF1 and FGF2 upregulated the expression of Notch and decreased expression of Delta1 in the NEP cells. In addition, the inhibitory response of the cells to the FGFs could be overcome by downregulating Notch1 expression and by disrupting Notch cleavage and signaling by the ablation of the Presenilin1 gene. These results indicate that FGF1 and FGF2 act via the Notch pathway, either directly or indirectly, to inhibit differentiation. Thus, signaling through the Notch receptor may be a common regulator of neuronal differentiation within the developing forebrain.

  2. Human-induced pluripotent stem cell-derived cardiomyocytes for studies of cardiac ion transporters

    PubMed Central

    Fine, Michael; Lu, Fang-Min; Lin, Mei-Jung; Moe, Orson; Wang, Hao-Ran

    2013-01-01

    Human-induced pluripotent stem cells (hiPSCs) can differentiate into functional cardiomyocytes (iCell Cardiomyocytes) with ion channel activities that are remarkably similar to adult cardiomyocytes. Here, we extend this characterization to cardiac ion transporters. Additionally, we document facile molecular biological manipulation of iCell Cardiomyocytes to overexpress and knockdown transporters and regulatory proteins. Na/Ca exchange (NCX1) and Na/K pump currents were recorded via patch clamp, and Na/H and Cl/OH exchanges were recorded via oscillating proton-selective microelectrodes during patch clamp. Flux densities of all transport systems are similar to those of nonrodent adult cardiomyocytes. NCX1 protein and NCX1 currents decline after NCX1 small interfering (si)RNA transfection with similar time courses (τ ≈ 2 days), and an NCX1-Halo fusion protein is internalized after its extracellular labeling by AlexaFluor488 Ligand with a similar time course. Loss of the cardiac regulatory protein phospholemman (PLM) occurs over a longer time course (τ ≈ 60 h) after PLM small interfering RNA transfection. Similar to multiple previous reports for adult cardiomyocytes, Na/K pump currents in iCell Cardiomyocytes are not enhanced by activating cAMP production with either maximal or submaximal cytoplasmic Na and using either forskolin or isoproterenol to activate adenylate cyclases. Finally, we describe Ca influx-dependent changes of iCell Cardiomyocyte capacitance (Cm). Large increases of Cm occur during Ca influx via NCX1, thereby documenting large internal membrane reserves that can fuse to the sarcolemma, and subsequent declines of Cm document active endocytic processes. Together, these results document a great potential of iCell Cardiomyocytes for both short- and long-term studies of cardiac ion transporters and their regulation. PMID:23804202

  3. Mechanical stress regulation of plant growth and development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Myers, P. N.

    1995-01-01

    The authors introduce the chapter with a discussion of lessons from nature, agriculture, and landscapes; terms and definitions; and an historical perspective of mechanical stress regulation of plant growth and development. Topics include developmental responses to mechanical stress; mechanical stress-environment interactions; metabolic, productivity, and compositional changes; hormonal involvement; mechanoperception and early transduction mechanisms; applications in agriculture; and research implications. The discussion of hormonal involvement in mechanical stress physiology includes ethylene, auxin, gibberellins, and other phytohormones. The discussion of applications in agriculture examines windbreaks, nursery practices, height control and conditioning, and enhancement of growth and productivity. Implications for research are related to handling plant materials, space biology, and future research needs.

  4. Ubiquitination-dependent mechanisms regulate synaptic growth and function.

    PubMed

    DiAntonio, A; Haghighi, A P; Portman, S L; Lee, J D; Amaranto, A M; Goodman, C S

    2001-07-26

    The covalent attachment of ubiquitin to cellular proteins is a powerful mechanism for controlling protein activity and localization. Ubiquitination is a reversible modification promoted by ubiquitin ligases and antagonized by deubiquitinating proteases. Ubiquitin-dependent mechanisms regulate many important processes including cell-cycle progression, apoptosis and transcriptional regulation. Here we show that ubiquitin-dependent mechanisms regulate synaptic development at the Drosophila neuromuscular junction (NMJ). Neuronal overexpression of the deubiquitinating protease fat facets leads to a profound disruption of synaptic growth control; there is a large increase in the number of synaptic boutons, an elaboration of the synaptic branching pattern, and a disruption of synaptic function. Antagonizing the ubiquitination pathway in neurons by expression of the yeast deubiquitinating protease UBP2 (ref. 5) also produces synaptic overgrowth and dysfunction. Genetic interactions between fat facets and highwire, a negative regulator of synaptic growth that has structural homology to a family of ubiquitin ligases, suggest that synaptic development may be controlled by the balance between positive and negative regulators of ubiquitination.

  5. p27 Protein Protects Metabolically Stressed Cardiomyocytes from Apoptosis by Promoting Autophagy*

    PubMed Central

    Sun, Xuetao; Momen, Abdul; Wu, Jun; Noyan, Hossein; Li, Renke; von Harsdorf, Rüdiger; Husain, Mansoor

    2014-01-01

    p27Kip1 (p27), a key regulator of cell division, has been implicated in autophagy of cancer cells. However, its role in autophagy, the evolutionarily conserved catabolic process that enables cells to remove unwanted proteins and damaged organelles, had not been examined in the heart. Here we report that ectopic delivery of a p27 fusion protein (TAT-p27) was sufficient to induce autophagy in neonatal rat ventricular cardiomyocytes in vitro, under basal conditions and after glucose deprivation. Conversely, lentivirus-delivered shRNA against p27 successfully reduced p27 levels and suppressed basal and glucose-deprived levels of autophagy in cardiomyocytes in vitro. Glucose deprivation mimics myocardial ischemia and induces apoptosis in cardiomyocytes. During glucose deprivation, TAT-p27 inhibited apoptosis, whereas down-regulation of p27 decreased survival of cardiomyocytes. However, inhibition of autophagy by pharmacological (3-methyladenine, chloroquine, or bafilomycin A1) or genetic approaches (siRNA-mediated knockdown of Atg5) sensitized cardiomyocytes to glucose deprivation-induced apoptosis, even in the presence of TAT-p27. TAT-p27 was also able to provoke greater levels of autophagy in resting and fasting cardiomyocytes in vivo. Further, TAT-p27 enhanced autophagy and repressed cardiomyocytes apoptosis, improved cardiac function, and reduced infarct size following myocardial infarction. Again, these effects were lost when cardiac autophagy in vivo was blocked by chloroquine. Taken together, these data show that p27 positively regulates cardiac autophagy in vitro and in vivo, at rest and after metabolic stress, and that TAT-p27 inhibits apoptosis by promoting autophagy in glucose-deprived cardiomyocytes in vitro and in post-myocardial infarction hearts in vivo. PMID:24794871

  6. Cyp26b1 within the growth plate regulates bone growth in juvenile mice.

    PubMed

    Minegishi, Yoshiki; Sakai, Yasuo; Yahara, Yasuhito; Akiyama, Haruhiko; Yoshikawa, Hideki; Hosokawa, Ko; Tsumaki, Noriyuki

    2014-11-07

    Retinoic acid (RA) is an active metabolite of vitamin A and plays important roles in embryonic development. CYP26 enzymes degrade RA and have specific expression patterns that produce a RA gradient, which regulates the patterning of various structures in the embryo. However, it has not been addressed whether a RA gradient also exists and functions in organs after birth. We found localized RA activities in the diaphyseal portion of the growth plate cartilage were associated with the specific expression of Cyp26b1 in the epiphyseal portion in juvenile mice. To disturb the distribution of RA, we generated mice lacking Cyp26b1 specifically in chondrocytes (Cyp26b1(Δchon) cKO). These mice showed reduced skeletal growth in the juvenile stage. Additionally, their growth plate cartilage showed decreased proliferation rates of proliferative chondrocytes, which was associated with a reduced height in the zone of proliferative chondrocytes, and closed focally by four weeks of age, while wild-type mouse growth plates never closed. Feeding the Cyp26b1 cKO mice a vitamin A-deficient diet partially reversed these abnormalities of the growth plate cartilage. These results collectively suggest that Cyp26b1 in the growth plate regulates the proliferation rates of chondrocytes and is responsible for the normal function of the growth plate and growing bones in juvenile mice, probably by limiting the RA distribution in the growth plate proliferating zone.

  7. Mathematical model of mouse embryonic cardiomyocyte excitation-contraction coupling.

    PubMed

    Korhonen, Topi; Rapila, Risto; Tavi, Pasi

    2008-10-01

    Excitation-contraction (E-C) coupling is the mechanism that connects the electrical excitation with cardiomyocyte contraction. Embryonic cardiomyocytes are not only capable of generating action potential (AP)-induced Ca(2+) signals and contractions (E-C coupling), but they also can induce spontaneous pacemaking activity. The spontaneous activity originates from spontaneous Ca(2+) releases from the sarcoplasmic reticulum (SR), which trigger APs via the Na(+)/Ca(2+) exchanger (NCX). In the AP-driven mode, an external stimulus triggers an AP and activates voltage-activated Ca(2+) intrusion to the cell. These complex and unique features of the embryonic cardiomyocyte pacemaking and E-C coupling have never been assessed with mathematical modeling. Here, we suggest a novel mathematical model explaining how both of these mechanisms can coexist in the same embryonic cardiomyocytes. In addition to experimentally characterized ion currents, the model includes novel heterogeneous cytosolic Ca(2+) dynamics and oscillatory SR Ca(2+) handling. The model reproduces faithfully the experimentally observed fundamental features of both E-C coupling and pacemaking. We further validate our model by simulating the effect of genetic modifications on the hyperpolarization-activated current, NCX, and the SR Ca(2+) buffer protein calreticulin. In these simulations, the model produces a similar functional alteration to that observed previously in the genetically engineered mice, and thus provides mechanistic explanations for the cardiac phenotypes of these animals. In general, this study presents the first model explaining the underlying cellular mechanism for the origin and the regulation of the heartbeat in early embryonic cardiomyocytes.

  8. Mathematical Model of Mouse Embryonic Cardiomyocyte Excitation–Contraction Coupling

    PubMed Central

    Korhonen, Topi; Rapila, Risto; Tavi, Pasi

    2008-01-01

    Excitation–contraction (E–C) coupling is the mechanism that connects the electrical excitation with cardiomyocyte contraction. Embryonic cardiomyocytes are not only capable of generating action potential (AP)-induced Ca2+ signals and contractions (E–C coupling), but they also can induce spontaneous pacemaking activity. The spontaneous activity originates from spontaneous Ca2+ releases from the sarcoplasmic reticulum (SR), which trigger APs via the Na+/Ca2+ exchanger (NCX). In the AP-driven mode, an external stimulus triggers an AP and activates voltage-activated Ca2+ intrusion to the cell. These complex and unique features of the embryonic cardiomyocyte pacemaking and E–C coupling have never been assessed with mathematical modeling. Here, we suggest a novel mathematical model explaining how both of these mechanisms can coexist in the same embryonic cardiomyocytes. In addition to experimentally characterized ion currents, the model includes novel heterogeneous cytosolic Ca2+ dynamics and oscillatory SR Ca2+ handling. The model reproduces faithfully the experimentally observed fundamental features of both E–C coupling and pacemaking. We further validate our model by simulating the effect of genetic modifications on the hyperpolarization-activated current, NCX, and the SR Ca2+ buffer protein calreticulin. In these simulations, the model produces a similar functional alteration to that observed previously in the genetically engineered mice, and thus provides mechanistic explanations for the cardiac phenotypes of these animals. In general, this study presents the first model explaining the underlying cellular mechanism for the origin and the regulation of the heartbeat in early embryonic cardiomyocytes. PMID:18794378

  9. Aromatic fluorine compounds. VIII. Plant growth regulators and intermediates

    USGS Publications Warehouse

    Finger, G.C.; Gortatowski, M.J.; Shiley, R.H.; White, R.H.

    1959-01-01

    The preparation and properties of 41 fluorophenoxyacetic acids, 4 fluorophenoxypropionic acids, 2 fluorobenzoic acids, several indole derivatives, and a number of miscellaneous compounds are described. Data are given for many intermediates such as new fluorinated phenols, anisoles, anilines and nitrobenzenes. Most of the subject compounds are related to a number of well-known herbicides or plant growth regulators such as 2,4-D, 2,4,5-T and others.

  10. Ihh signaling regulates mandibular symphysis development and growth.

    PubMed

    Sugito, H; Shibukawa, Y; Kinumatsu, T; Yasuda, T; Nagayama, M; Yamada, S; Minugh-Purvis, N; Pacifici, M; Koyama, E

    2011-05-01

    Symphyseal secondary cartilage is important for mandibular development, but the molecular mechanisms underlying its formation remain largely unknown. Here we asked whether Indian hedgehog (Ihh) regulates symphyseal cartilage development and growth. By embryonic days 16.5 to 18.5, Sox9-expressing chondrocytes formed within condensed Tgfβ-1/Runx2-expressing mesenchymal cells at the prospective symphyseal joint site, and established a growth-plate-like structure with distinct Ihh, collagen X, and osteopontin expression patterns. In post-natal life, mesenchymal cells expressing the Ihh receptor Patched1 were present anterior to the Ihh-expressing secondary cartilage, proliferated, differentiated into chondrocytes, and contributed to anterior growth of alveolar bone. In Ihh-null mice, however, symphyseal development was defective, mainly because of enhanced chondrocyte maturation and reduced proliferation of chondroprogenitor cells. Proliferation was partially restored in dual Ihh;Gli3 mutants, suggesting that Gli3 is normally a negative regulator of symphyseal development. Thus, Ihh signaling is essential for symphyseal cartilage development and anterior mandibular growth.

  11. ROS Regulation of Polar Growth in Plant Cells1[OPEN

    PubMed Central

    Mangano, Silvina; Juárez, Silvina Paola Denita

    2016-01-01

    Root hair cells and pollen tubes, like fungal hyphae, possess a typical tip or polar cell expansion with growth limited to the apical dome. Cell expansion needs to be carefully regulated to produce a correct shape and size. Polar cell growth is sustained by oscillatory feedback loops comprising three main components that together play an important role regulating this process. One of the main components are reactive oxygen species (ROS) that, together with calcium ions (Ca2+) and pH, sustain polar growth over time. Apoplastic ROS homeostasis controlled by NADPH oxidases as well as by secreted type III peroxidases has a great impact on cell wall properties during cell expansion. Polar growth needs to balance a focused secretion of new materials in an extending but still rigid cell wall in order to contain turgor pressure. In this review, we discuss the gaps in our understanding of how ROS impact on the oscillatory Ca2+ and pH signatures that, coordinately, allow root hair cells and pollen tubes to expand in a controlled manner to several hundred times their original size toward specific signals. PMID:27208283

  12. Autophagy protects cardiomyocytes from the myocardial ischaemia-reperfusion injury through the clearance of CLP36

    PubMed Central

    Li, Shiguo; Liu, Chao; Gu, Lei; Wang, Lina; Shang, Yongliang; Liu, Qiong; Wan, Junyi; Shi, Jian; Wang, Fang; Xu, Zhiliang; Ji, Guangju

    2016-01-01

    Cardiovascular disease (CVD) is the leading cause of the death worldwide. An increasing number of studies have found that autophagy is involved in the progression or prevention of CVD. However, the precise mechanism of autophagy in CVD, especially the myocardial ischaemia-reperfusion injury (MI/R injury), is unclear and controversial. Here, we show that the cardiomyocyte-specific disruption of autophagy by conditional knockout of Atg7 leads to severe contractile dysfunction, myofibrillar disarray and vacuolar cardiomyocytes. A negative cytoskeleton organization regulator, CLP36, was found to be accumulated in Atg7-deficient cardiomyocytes. The cardiomyocyte-specific knockout of Atg7 aggravates the MI/R injury with cardiac hypertrophy, contractile dysfunction, myofibrillar disarray and severe cardiac fibrosis, most probably due to CLP36 accumulation in cardiomyocytes. Altogether, this work reveals autophagy may protect cardiomyocytes from the MI/R injury through the clearance of CLP36, and these findings define a novel relationship between autophagy and the regulation of stress fibre in heart. PMID:27512143

  13. Intermedin 1-53 Inhibits Myocardial Fibrosis in Rats by Down-Regulating Transforming Growth Factor-β

    PubMed Central

    Fang, Jian; Luan, Jiangwei; Zhu, Gaohong; Qi, Chang; Yang, Zhiyong; Zhao, Sheng; Li, Bin; Zhang, Xinzhong; Guo, Naipeng; Li, Xiaodong; Wang, Dandan

    2017-01-01

    Background Myocardial fibrosis is the result of persistent anoxia and ischemic myocardial fibers caused by coronary atherosclerotic stenosis, which lead to heart failure, threatening the patient’s life. This study aimed to explore the regulatory role of intermedin 1-53 (IMD1-53) in cardiac fibrosis using neonatal rat cardiac fibroblasts and a myocardial infarction (MI) rat model both in vitro and in vivo. Material/Methods The Western blot method was used to detect the protein expression of collagen I and collagen III in myocardial fibroblasts. The SYBR Green I real-time quantitative polymerase chain reaction (PCR) assay was used to detect the mRNA expression of collagen type I and III, IMD1-53 calcitonin receptor-like receptor (CRLR), transforming growth factor-β (TGF-β), and matrix metalloproteinase-2 (MMP-2). Masson staining was used to detect the area changes of myocardial fibrosis in MI rats. Results Results in vivo showed that IMD1-53 reduced the scar area on the heart of MI rats and inhibited the expression of collagen type I and III both in mRNA and protein. Results of an in vitro study showed that IMD1-53 inhibited the transformation of cardiomyocytes into myofibroblasts caused by angiotensin II (Ang II). The further mechanism study showed that IMD1-53 inhibited the expression of TGF-β and the phosphorylation of smad3, which further up-regulated the expression of MMP-2. Conclusions IMD1-53 is an effective anti-fibrosis hormone that inhibits cardiac fibrosis formation after MI by down-regulating the expression of TGF-β and the phosphorylation of smad3, blocking fibrous signal pathways, and up-regulating the expression of MMP-2, thereby demonstrating its role in regression of myocardial fibrosis. PMID:28065931

  14. Nucleolin is regulated both at the level of transcription and translation

    SciTech Connect

    Bicknell, Katrina; Brooks, Gavin; Kaiser, Pete; Chen Hongying; Dove, Brian K.; Hiscox, Julian A.; E-mail: j.a.hiscox@leeds.ac.uk

    2005-07-08

    Nucleolin is a multi-functional protein that is located to the nucleolus. In tissue culture cells, the stability of nucleolin is related to the proliferation status of the cell. During development, rat cardiomyocytes proliferate actively with increases in the mass of the heart being due to both hyperplasia and hypertrophy. The timing of this shift in the phenotype of the myocyte from one capable of undergoing hyperplasia to one that can grow only by hypertrophy occurs within 4 days of post-natal development. Thus, cardiomyocytes are an ideal model system in which to study the regulation of nucleolin during growth in vivo. Using Western blot and quantitative RT-PCR (TaqMan) we found that the amount of nucleolin is regulated both at the level of transcription and translation during the development of the cardiomyocyte. However, in cells which had exited the cell cycle and were subsequently given a hypertrophic stimulus, nucleolin was regulated post-transcriptionally.

  15. Regulation of dendrite growth and maintenance by exocytosis.

    PubMed

    Peng, Yun; Lee, Jiae; Rowland, Kimberly; Wen, Yuhui; Hua, Hope; Carlson, Nicole; Lavania, Shweta; Parrish, Jay Z; Kim, Michael D

    2015-12-01

    Dendrites lengthen by several orders of magnitude during neuronal development, but how membrane is allocated in dendrites to facilitate this growth remains unclear. Here, we report that Ras opposite (Rop), the Drosophila ortholog of the key exocytosis regulator Munc18-1 (also known as STXBP1), is an essential factor mediating dendrite growth. Neurons with depleted Rop function exhibit reduced terminal dendrite outgrowth followed by primary dendrite degeneration, suggestive of differential requirements for exocytosis in the growth and maintenance of different dendritic compartments. Rop promotes dendrite growth together with the exocyst, an octameric protein complex involved in tethering vesicles to the plasma membrane, with Rop-exocyst complexes and exocytosis predominating in primary dendrites over terminal dendrites. By contrast, membrane-associated proteins readily diffuse from primary dendrites into terminals, but not in the reverse direction, suggesting that diffusion, rather than targeted exocytosis, supplies membranous material for terminal dendritic growth, revealing key differences in the distribution of materials to these expanding dendritic compartments.

  16. Regulation of plant growth and development by the GROWTH-REGULATING FACTOR and GRF-INTERACTING FACTOR duo.

    PubMed

    Hoe Kim, Jeong; Tsukaya, Hirokazu

    2015-10-01

    Transcription factors are key regulators of gene expression and play pivotal roles in all aspects of living organisms. Therefore, identification and functional characterization of transcription factors is a prerequisite step toward understanding life. This article reviews molecular and biological functions of the two transcription regulator families, GROWTH-REGULATING FACTOR (GRF) and GRF-INTERACTING FACTOR (GIF), which have only recently been recognized. A myriad of experimental evidence clearly illustrates that GRF and GIF are bona fide partner proteins and form a plant-specific transcriptional complex. One of the most conspicuous outcomes from this research field is that the GRF-GIF duo endows the primordial cells of vegetative and reproductive organs with a meristematic specification state, guaranteeing the supply of cells for organogenesis and successful reproduction. It has recently been shown that GIF1 proteins, also known as ANGUSTIFOLIA3, recruit chromatin remodelling complexes to target genes, and that AtGRF expression is directly activated by the floral identity factors, APETALA1 and SEPALLATA3, providing an important insight into understanding of the action of GRF-GIF. Moreover, GRF genes are extensively subjected to post-transcriptional control by microRNA396, revealing the presence of a complex regulatory circuit in regulation of plant growth and development by the GRF-GIF duo.

  17. Myogenic regulatory transcription factors regulate growth in rhabdomyosarcoma

    PubMed Central

    Tenente, Inês M; Hayes, Madeline N; Ignatius, Myron S; McCarthy, Karin; Yohe, Marielle; Sindiri, Sivasish; Gryder, Berkley; Oliveira, Mariana L; Ramakrishnan, Ashwin; Tang, Qin; Chen, Eleanor Y; Petur Nielsen, G; Khan, Javed; Langenau, David M

    2017-01-01

    Rhabdomyosarcoma (RMS) is a pediatric malignacy of muscle with myogenic regulatory transcription factors MYOD and MYF5 being expressed in this disease. Consensus in the field has been that expression of these factors likely reflects the target cell of transformation rather than being required for continued tumor growth. Here, we used a transgenic zebrafish model to show that Myf5 is sufficient to confer tumor-propagating potential to RMS cells and caused tumors to initiate earlier and have higher penetrance. Analysis of human RMS revealed that MYF5 and MYOD are mutually-exclusively expressed and each is required for sustained tumor growth. ChIP-seq and mechanistic studies in human RMS uncovered that MYF5 and MYOD bind common DNA regulatory elements to alter transcription of genes that regulate muscle development and cell cycle progression. Our data support unappreciated and dominant oncogenic roles for MYF5 and MYOD convergence on common transcriptional targets to regulate human RMS growth. DOI: http://dx.doi.org/10.7554/eLife.19214.001 PMID:28080960

  18. Cholesterol depletion impairs contractile machinery in neonatal rat cardiomyocytes

    PubMed Central

    Hissa, Barbara; Oakes, Patrick W.; Pontes, Bruno; Ramírez-San Juan, Guillermina; Gardel, Margaret L.

    2017-01-01

    Cholesterol regulates numerous cellular processes. Depleting its synthesis in skeletal myofibers induces vacuolization and contraction impairment. However, little is known about how cholesterol reduction affects cardiomyocyte behavior. Here, we deplete cholesterol by incubating neonatal cardiomyocytes with methyl-beta-cyclodextrin. Traction force microscopy shows that lowering cholesterol increases the rate of cell contraction and generates defects in cell relaxation. Cholesterol depletion also increases membrane tension, Ca2+ spikes frequency and intracellular Ca2+ concentration. These changes can be correlated with modifications in caveolin-3 and L-Type Ca2+ channel distributions across the sarcolemma. Channel regulation is also compromised since cAMP-dependent PKA activity is enhanced, increasing the probability of L-Type Ca2+ channel opening events. Immunofluorescence reveals that cholesterol depletion abrogates sarcomeric organization, changing spacing and alignment of α-actinin bands due to increase in proteolytic activity of calpain. We propose a mechanism in which cholesterol depletion triggers a signaling cascade, culminating with contraction impairment and myofibril disruption in cardiomyocytes. PMID:28256617

  19. Spatial Allocation and Specification of Cardiomyocytes during Zebrafish Embryogenesis

    PubMed Central

    Fukui, Hajime; Chiba, Ayano; Miyazaki, Takahiro; Takano, Haruko; Ishikawa, Hiroyuki; Omori, Toyonori

    2017-01-01

    Incomplete development and severe malformation of the heart result in miscarriage of embryos because of its malfunction as a pump for circulation. During cardiogenesis, development of the heart is precisely coordinated by the genetically-primed program that is revealed by the sequential expression of transcription factors. It is important to investigate how spatial allocation of the heart containing cardiomyocytes and other mesoderm-derived cells is determined. In addition, the molecular mechanism underlying cardiomyocyte differentiation still remains elusive. The location of ectoderm-, mesoderm-, and endoderm-derived organs is determined by their initial allocation and subsequent mutual cell-cell interactions or paracrine-based regulation. In the present work, we provide an overview of cardiac development controlled by the germ layers and discuss the points that should be uncovered in future for understanding cardiogenesis. PMID:28382067

  20. Evidence for Cardiomyocyte Renewal in Humans

    SciTech Connect

    Bergmann, O; Bhardwaj, R D; Bernard, S; Zdunek, S; Barnabe-Heider, F; Walsh, S; Zupicich, J; Alkass, K; Buchholz, B A; Druid, H; Jovinge, S; Frisen, J

    2008-10-14

    It has been difficult to establish whether we are limited to the heart muscle cells we are born with or if cardiomyocytes are generated also later in life. We have taken advantage of the integration of {sup 14}C, generated by nuclear bomb tests during the Cold War, into DNA to establish the age of cardiomyocytes in humans. We report that cardiomyocytes renew, with a gradual decrease from 1% turning over annually at the age of 20 to 0.3% at the age of 75. Less than 50% of cardiomyocytes are exchanged during a normal lifespan. The capacity to generate cardiomyocytes in the adult human heart suggests that it may be rational to work towards the development of therapeutic strategies aiming to stimulate this process in cardiac pathologies.

  1. Evidence for cardiomyocyte renewal in humans.

    PubMed

    Bergmann, Olaf; Bhardwaj, Ratan D; Bernard, Samuel; Zdunek, Sofia; Barnabé-Heider, Fanie; Walsh, Stuart; Zupicich, Joel; Alkass, Kanar; Buchholz, Bruce A; Druid, Henrik; Jovinge, Stefan; Frisén, Jonas

    2009-04-03

    It has been difficult to establish whether we are limited to the heart muscle cells we are born with or if cardiomyocytes are generated also later in life. We have taken advantage of the integration of carbon-14, generated by nuclear bomb tests during the Cold War, into DNA to establish the age of cardiomyocytes in humans. We report that cardiomyocytes renew, with a gradual decrease from 1% turning over annually at the age of 25 to 0.45% at the age of 75. Fewer than 50% of cardiomyocytes are exchanged during a normal life span. The capacity to generate cardiomyocytes in the adult human heart suggests that it may be rational to work toward the development of therapeutic strategies aimed at stimulating this process in cardiac pathologies.

  2. Mammalian target of rapamycin is essential for cardiomyocyte survival and heart development in mice

    SciTech Connect

    Zhang, Pengpeng; Shan, Tizhong; Liang, Xinrong; Deng, Changyan; Kuang, Shihuan

    2014-09-12

    Highlights: • mTOR is a critical regulator of many biological processes yet its function in heart is not well understood. • MCK-Cre/Mtor{sup flox/flox} mice were established to delete Mtor in cardiomyocytes. • The mTOR-mKO mice developed normally but die prematurely within 5 weeks after birth due to heart disease. • The mTOR-mKO mice had dilated myocardium and increased cell death. • mTOR-mKO hearts had reduced expression of metabolic genes and activation of mTOR target proteins. - Abstract: Mammalian target of rapamycin (mTOR) is a critical regulator of protein synthesis, cell proliferation and energy metabolism. As constitutive knockout of Mtor leads to embryonic lethality, the in vivo function of mTOR in perinatal development and postnatal growth of heart is not well defined. In this study, we established a muscle-specific mTOR conditional knockout mouse model (mTOR-mKO) by crossing MCK-Cre and Mtor{sup flox/flox} mice. Although the mTOR-mKO mice survived embryonic and perinatal development, they exhibited severe postnatal growth retardation, cardiac muscle pathology and premature death. At the cellular level, the cardiac muscle of mTOR-mKO mice had fewer cardiomyocytes due to apoptosis and necrosis, leading to dilated cardiomyopathy. At the molecular level, the cardiac muscle of mTOR-mKO mice expressed lower levels of fatty acid oxidation and glycolysis related genes compared to the WT littermates. In addition, the mTOR-mKO cardiac muscle had reduced Myh6 but elevated Myh7 expression, indicating cardiac muscle degeneration. Furthermore, deletion of Mtor dramatically decreased the phosphorylation of S6 and AKT, two key targets downstream of mTORC1 and mTORC2 mediating the normal function of mTOR. These results demonstrate that mTOR is essential for cardiomyocyte survival and cardiac muscle function.

  3. Role of Nodal-PITX2C signaling pathway in glucose-induced cardiomyocyte hypertrophy.

    PubMed

    Su, Dongmei; Jing, Sun; Guan, Lina; Li, Qian; Zhang, Huiling; Gao, Xiaobo; Ma, Xu

    2014-06-01

    Pathological cardiac hypertrophy is a major cause of morbidity and mortality in cardiovascular disease. Recent studies have shown that cardiomyocytes, in response to high glucose (HG) stimuli, undergo hypertrophic growth. While much work still needs to be done to elucidate this important mechanism of hypertrophy, previous works have showed that some pathways or genes play important roles in hypertrophy. In this study, we showed that sublethal concentrations of glucose (25 mmol/L) could induce cardiomyocyte hypertrophy with an increase in the cellular surface area and the upregulation of the atrial natriuretic peptide (ANP) gene, a hypertrophic marker. High glucose (HG) treatments resulted in the upregulation of the Nodal gene, which is under-expressed in cardiomyocytes. We also determined that the knockdown of the Nodal gene resisted HG-induced cardiomyocyte hypertrophy. The overexpression of Nodal was able to induce hypertrophy in cardiomyocytes, which was associated with the upregulation of the PITX2C gene. We also showed that increases in the PITX2C expression, in response to Nodal, were mediated by the Smad4 signaling pathway. This study is highly relevant to the understanding of the effects of the Nodal-PITX2C pathway on HG-induced cardiomyocyte hypertrophy, as well as the related molecular mechanisms.

  4. Fluoxetine regulates cell growth inhibition of interferon-α.

    PubMed

    Lin, Yu-Min; Yu, Bu-Chin; Chiu, Wen-Tai; Sun, Hung-Yu; Chien, Yu-Chieh; Su, Hui-Chen; Yen, Shu-Yang; Lai, Hsin-Wen; Bai, Chyi-Huey; Young, Kung-Chia; Tsao, Chiung-Wen

    2016-10-01

    Fluoxetine, a well-known anti-depression agent, may act as a chemosensitizer to assist and promote cancer therapy. However, how fluoxetine regulates cellular signaling to enhance cellular responses against tumor cell growth remains unclear. In the present study, addition of fluoxetine promoted growth inhibition of interferon-alpha (IFN-α) in human bladder carcinoma cells but not in normal uroepithelial cells through lessening the IFN-α-induced apoptosis but switching to cause G1 arrest, and maintaining the IFN-α-mediated reduction in G2/M phase. Activations and signal transducer and transactivator (STAT)-1 and peroxisome proliferator-activated receptor alpha (PPAR-α) were involved in this process. Chemical inhibitions of STAT-1 or PPAR-α partially rescued bladder carcinoma cells from IFN-α-mediated growth inhibition via blockades of G1 arrest, cyclin D1 reduction, p53 downregulation and p27 upregulation in the presence of fluoxetine. However, the functions of both proteins were not involved in the control of fluoxetine over apoptosis and maintained the declined G2/M phase of IFN-α. These results indicated that activation of PPAR-α and STAT-1 participated, at least in part, in growth inhibition of IFN-α in the presence of fluoxetine.

  5. Metabolic switch and hypertrophy of cardiomyocytes following treatment with angiotensin II are prevented by AMP-activated protein kinase.

    PubMed

    Stuck, Bettina Johanna; Lenski, Matthias; Böhm, Michael; Laufs, Ulrich

    2008-11-21

    Angiotensin II induces cardiomyocyte hypertrophy, but its consequences on cardiomyocyte metabolism and energy supply are not completely understood. Here we investigate the effect of angiotensin II on glucose and fatty acid utilization and the modifying role of AMP-activated protein kinase (AMPK), a key regulator of metabolism and proliferation. Treatment of H9C2 cardiomyocytes with angiotensin II (Ang II, 1 microm, 4 h) increased [(3)H]leucine incorporation, up-regulated the mRNA expression of the hypertrophy marker genes MLC, ANF, BNP, and beta-MHC, and decreased the phosphorylation of the negative mTOR-regulator tuberin (TSC-2). Rat neonatal cardiomyocytes showed similar results. Western blot analysis revealed a time- and concentration-dependent down-regulation of AMPK-phosphorylation in the presence of angiotensin II, whereas the protein expression of the catalytic alpha-subunit remained unchanged. This was paralleled by membrane translocation of glucose-transporter type 4 (GLUT4), increased uptake of [(3)H]glucose and transient down-regulation of phosphorylation of acetyl-CoA carboxylase (ACC), whereas fatty acid uptake remained unchanged. Similarly, short-term transaortic constriction in mice resulted in down-regulation of P-AMPK and P-ACC but up-regulation of GLUT4 membrane translocation in the heart. Preincubation of cardiomyocytes with the AMPK stimulator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR; 1 mM, 4 h) completely prevented the angiotensin II-induced cardiomyocytes hypertrophy. In addition, AICAR reversed the metabolic effects of angiotensin II: GLUT4 translocation was reduced, but ACC phosphorylation and TSC phosphorylation were elevated. In summary, angiotensin II-induced hypertrophy of cardiomyocytes is accompanied by decreased activation of AMPK, increased glucose uptake, and decreased mTOR inhibition. Stimulation with the AMPK activator AICAR reverses these metabolic changes, increases fatty acid utilization, and inhibits

  6. AMPK Regulation of Cell Growth, Apoptosis, Autophagy, and Bioenergetics.

    PubMed

    Paz, Marina Villanueva; Cotán, David; Maraver, Juan Garrido; Oropesa-Ávila, Manuel; de la Mata, Mario; Pavón, Ana Delgado; de Lavera, Isabel; Gómez, Elizabet Alcocer; Córdoba, Mónica Álvarez; Alcázar, José A Sánchez

    2016-01-01

    In eukaryotic cells, AMP-activated protein kinase (AMPK) generally promotes catabolic pathways that produce ATP and at the same time inhibits anabolic pathways involved in different processes that consume ATP. As an energy sensor, AMPK is involved in the main cellular functions implicated in cell fate, such as cell growth and autophagy.Recently, AMPK has been connected with apoptosis regulation, although the molecular mechanism by which AMPK induces and/or inhibits cell death is not clear.This chapter reviews the essential role of AMPK in signaling pathways that respond to cellular stress and damage, highlighting the complex and reciprocal regulation between AMPK and their targets and effectors. The therapeutic implications of the role of AMPK in different pathologies such as diabetes, cancer, or mitochondrial dysfunctions are still controversial, and it is necessary to further investigate the molecular mechanisms underlying AMPK activation.

  7. Astrocyte growth is regulated by neuropeptides through Tis 8 and basic fibroblast growth factor.

    PubMed Central

    Hu, R M; Levin, E R

    1994-01-01

    The important intracellular mechanisms of astrocyte growth are not well defined. Using an inhibitor of astrocyte proliferation, atrial natriuretic peptide (ANP), and the glial mitogen endothelin (ET-3), we sought a common pathway for growth regulation in these neural cells. In cultured fetal rat diencephalic astrocytes, ANP selectively and rapidly inhibited the Tis 8 immediate early gene and protein. After 4 h, ANP selectively inhibited the basic fibroblast growth factor (bFGF) gene and protein. ET-3 significantly stimulated both Tis 8 and bFGF mRNAs and protein, but also stimulated several other immediate early and growth factor/receptor genes. An antisense oligonucleotide to Tis 8 strongly prevented ET-stimulated thymidine incorporation, while the inhibitory action of ANP was enhanced. The Tis 8 antisense oligonucleotide also significantly reversed ET-stimulated bFGF transcription and enhanced the bFGF inhibition caused by ANP. In addition, an antisense oligonucleotide to bFGF significantly reversed the ET-stimulated thymidine incorporation and enhanced the ANP inhibition of DNA synthesis. The sequential modulation of Tis 8, followed by bFGF, provides a novel mechanism for both positive and negative regulation of astrocyte growth by endogenous neuropeptides. Images PMID:8163680

  8. Regulation of skeletal muscle growth in fish by the growth hormone--insulin-like growth factor system.

    PubMed

    Fuentes, Eduardo N; Valdés, Juan Antonio; Molina, Alfredo; Björnsson, Björn Thrandur

    2013-10-01

    The growth hormone (GH)-insulin-like growth factor (IGF) system is the key promoter of growth in vertebrates; however, how this system modulates muscle mass in fish is just recently becoming elucidated. In fish, the GH induces muscle growth by modulating the expression of several genes belonging to the myostatin (MSTN), atrophy, GH, and IGF systems as well as myogenic regulatory factors (MRFs). The GH controls the expression of igf1 via Janus kinase 2 (JAK2)/signal transducers and activators of the transcription 5 (STAT5) signaling pathway, but it seems that it is not the major regulator. These mild effects of the GH on igf1 expression in fish muscle seem to be related with the presence of higher contents of truncated GH receptor1 (tGHR1) than full length GHR (flGHR1). IGFs in fish stimulate myogenic cell proliferation, differentiation, and protein synthesis through the MAPK/ERK and PI3K/AKT/TOR signaling pathways, concomitant with abolishing protein degradation and atrophy via the PI3K/AKT/FOXO signaling pathway. Besides these signaling pathways control the expression of several genes belonging to the atrophy and IGF systems. Particularly, IGFs and amino acid control the expression of igf1, thus, suggesting other of alternative signaling pathways regulating the transcription of this growth factor. The possible role of IGF binding proteins (IGFBPs) and the contribution of muscle-derived versus hepatic-produced IGF1 on fish muscle growth is also addressed. Thus, a comprehensive overview on the GH-IGF system regulating fish skeletal muscle growth is presented, as well as perspectives for future research in this field.

  9. Dexamethasone Treatment of Newborn Rats Decreases Cardiomyocyte Endowment in the Developing Heart through Epigenetic Modifications.

    PubMed

    Gay, Maresha S; Li, Yong; Xiong, Fuxia; Lin, Thant; Zhang, Lubo

    2015-01-01

    The potential adverse effect of synthetic glucocorticoid, dexamethasone therapy on the developing heart remains unknown. The present study investigated the effects of dexamethasone on cardiomyocyte proliferation and binucleation in the developing heart of newborn rats and evaluated DNA methylation as a potential mechanism. Dexamethasone was administered intraperitoneally in a three day tapered dose on postnatal day 1 (P1), 2 and 3 to rat pups in the absence or presence of a glucocorticoid receptor antagonist Ru486, given 30 minutes prior to dexamethasone. Cardiomyocytes from P4, P7 or P14 animals were analyzed for proliferation, binucleation and cell number. Dexamethasone treatment significantly increased the percentage of binucleated cardiomyocytes in the hearts of P4 pups, decreased myocyte proliferation in P4 and P7 pups, reduced cardiomyocyte number and increased the heart to body weight ratio in P14 pups. Ru486 abrogated the effects of dexamethasone. In addition, 5-aza-2'-deoxycytidine (5-AZA) blocked the effects of dexamethasone on binucleation in P4 animals and proliferation at P7, leading to recovered cardiomyocyte number in P14 hearts. 5-AZA alone promoted cardiomyocyte proliferation at P7 and resulted in a higher number of cardiomyocytes in P14 hearts. Dexamethasone significantly decreased cyclin D2, but not p27 expression in P4 hearts. 5-AZA inhibited global DNA methylation and blocked dexamethasone-mediated down-regulation of cyclin D2 in the heart of P4 pups. The findings suggest that dexamethasone acting on glucocorticoid receptors inhibits proliferation and stimulates premature terminal differentiation of cardiomyocytes in the developing heart via increased DNA methylation in a gene specific manner.

  10. Protein restriction does not impair adaptations induced in cardiomyocytes by exercise in rats.

    PubMed

    Cabral, C A C; Natali, A J; Natali, A Y; Novaes, R D; Lavorato, V N; Drumond, L R; Carneiro Júnior, M A; Silva, M F; Quintão-Junior, J F; Gontijo, L N; Silva, C H O; Felix, L B; Silva, M E

    2013-11-01

    The effect of a treadmill running program on physical performance and morphofunctional adaptations was investigated in control and malnourished rats. Male 4-week old Wistar rats were randomized in groups of 12 animals: control trained (CT), control sedentary (CS), malnourished trained (MT) and malnourished sedentary (MS). Control and malnourished animals received chow with 12% protein or 6% protein, respectively. Trained groups were subjected to a treadmill running program for 8 weeks. Physical performance, biochemical parameters, cardiomyocytes morphology and biomechanics were determined. Malnourished animals presented reduction in body mass, serum levels of total protein, albumin and hemoglobin compared to the control groups. At 1 and 3 Hz cardiomyocytes from CT and MT showed higher cell shortening, speed of contraction and relaxation compared to the other groups. At 3 Hz cardiomyocytes from MS showed reduction in cell shortening and speed of contraction compared to CS. Protein restriction does not prevent the improvement in physical performance or cardiomyocytes biomechanical efficiency and growth in response to exercise. These findings could represent a modulatory effect of exercise to maintain cardiomyocyte growth at the expense of reducing the rate of body growth in order to ensure proper cellular function in conditions of cardiovascular overload imposed by exercise.

  11. ETL, a novel seven-transmembrane receptor that is developmentally regulated in the heart. ETL is a member of the secretin family and belongs to the epidermal growth factor-seven-transmembrane subfamily.

    PubMed

    Nechiporuk, T; Urness, L D; Keating, M T

    2001-02-09

    Using differential display of rat fetal and postnatal cardiomyocytes, we have identified a novel seven-transmembrane receptor, ETL. The cDNA-predicted amino acid sequence of ETL indicated that it encodes a 738-aa protein composed of a large extracellular domain with epidermal growth factor (EGF)-like repeats, a seven-transmembrane domain, and a short cytoplasmic tail. ETL belongs to the secretin family of G-protein-coupled peptide hormone receptors and the EGF-TM7 subfamily of receptors. The latter are characterized by a variable number of extracellular EGF and cell surface domains and conserved seven transmembrane-spanning regions. ETL mRNA expression is up-regulated in the adult rat and human heart. In situ hybridization analyses revealed expression in rat cardiomyocytes and abundant expression in vascular and bronchiolar smooth muscle cells. In COS-7 cells transfected with Myc-tagged rat ETL, rat ETL exists as a stable dimer and undergoes endoproteolytic cleavage of the extracellular domain. The proteolytic activity can be abolished by a specific mutation, T455A, in this domain. In transfected mammalian cells, ETL is associated with cell membranes and is also observed in cytoplasmic vesicles. ETL is the first seven-transmembrane receptor containing EGF-like repeats that is developmentally regulated in the heart.

  12. GLP1 protects cardiomyocytes from palmitate-induced apoptosis via Akt/GSK3b/b-catenin pathway.

    PubMed

    Ying, Ying; Zhu, Huazhang; Liang, Zhen; Ma, Xiaosong; Li, Shiwei

    2015-12-01

    Activation of apoptosis in cardiomyocytes by saturated palmitic acids contributes to cardiac dysfunction in diabetic cardiomyopathy. Beta-catenin (b-catenin) is a transcriptional regulator of several genes involved in survival/anti-apoptosis. However, its role in palmitate-induced cardiomyocyte apoptosis remains unclear. Glucagon-like peptide 1 (GLP1) has been shown to exhibit potential cardioprotective properties. This study was designed to evaluate the role of b-catenin signalling in palmitate-induced cardiomyocyte apoptosis and the molecular mechanism underlying the protective effects of GLP1 on palmitate-stressed cardiomyocytes. Exposure of neonatal rat cardiomyocytes to palmitate increased the fatty acid transporter CD36-mediated intracellular lipid accumulation and cardiomyocyte apoptosis, decreased accumulation and nuclear translocation of active b-catenin, and reduced expression of b-catenin target protein survivin and BCL2. These detrimental effects of palmitate were significantly attenuated by GLP1 co-treatment. However, the anti-apoptotic effects of GLP1 were markedly abolished when b-catenin was silenced with a specific short hairpin RNA. Furthermore, analysis of the upstream molecules and mechanisms responsible for GLP1-associated cardiac protection revealed that GLP1 restored the decreased phosphorylation of protein kinase B (Akt) and glycogen synthase kinase-3b (GSK3b) in palmitate-stimulated cardiomyocytes. In contrast, inhibition of Akt with an Akt-specific inhibitor MK2206 or blockade of GLP1 receptor (GLP1R) with a competitive antagonist exendin-(9-39) significantly abrogated the GLP1-mediated activation of GSK3b/b-catenin signalling, leading to increased apoptosis in palmitate-stressed cardiomyocytes. Collectively, our results demonstrated for the first time that the attenuated b-catenin signalling may contribute to palmitate-induced cardiomyocyte apoptosis, while GLP1 can protect cardiomyocytes from palmitate-induced apoptosis through

  13. Interferons induce the expression of IFITM1 and IFITM3 and suppress the proliferation of rat neonatal cardiomyocytes.

    PubMed

    Lau, Samantha Lai-Yee; Yuen, Man-Leuk; Kou, Cecy Ying-Chuck; Au, Ka-Wing; Zhou, Junwei; Tsui, Stephen Kwok-Wing

    2012-03-01

    Cardiovascular diseases have been one of the leading killers among the human population worldwide. During the heart development, cardiomyocytes undergo a transition from hyperplastic to hypertrophic growth with an unclear underlying mechanism. In this study, we aim to investigate how interferons differentially stimulate the interferon-inducible transmembrane (IFITM) family proteins and further be involved in the process of heart development. The expression levels of three IFITM family members, IFITM1, IFITM2, and IFITM3 were investigated during Sprague-Dawley rat myocardial development and differentiation of H9C2 cardiomyocytes. The effects of interferon-α, -β, and -γ on DNA synthesis in H9C2 cells were also characterized. Up-regulation of IFITM1 and IFITM3 were observed during the heart development of Sprague-Dawley rat and the differentiation of H9C2 cells. Moreover, interferon-α and -β induce the expression of IFITM3 while interferon-γ up-regulates IFITM1. Finally, interferon-α and -β were demonstrated to inhibit DNA synthesis during H9C2 cell differentiation. Our results indicated interferons are potentially involved in the differentiation and cell proliferation during heart development.

  14. Endogenous retroviruses regulate periimplantation placental growth and differentiation

    PubMed Central

    Dunlap, Kathrin A.; Palmarini, Massimo; Varela, Mariana; Burghardt, Robert C.; Hayashi, Kanako; Farmer, Jennifer L.; Spencer, Thomas E.

    2006-01-01

    Endogenous retroviruses (ERVs) are fixed and abundant in the genomes of vertebrates. Circumstantial evidence suggests that ERVs play a role in mammalian reproduction, particularly placental morphogenesis, because intact ERV envelope genes were found to be expressed in the syncytiotrophoblasts of human and mouse placenta and to elicit fusion of cells in vitro. We report here in vivo and in vitro experiments finding that the envelope of a particular class of ERVs of sheep, endogenous Jaagsiekte sheep retroviruses (enJSRVs), regulates trophectoderm growth and differentiation in the periimplantation conceptus (embryo/fetus and associated extraembryonic membranes). The enJSRV envelope gene is expressed in the trophectoderm of the elongating ovine conceptus after day 12 of pregnancy. Loss-of-function experiments were conducted in utero by injecting morpholino antisense oligonucleotides on day 8 of pregnancy that blocked enJSRV envelope protein production in the conceptus trophectoderm. This approach retarded trophectoderm outgrowth during conceptus elongation and inhibited trophoblast giant binucleate cell differentiation as observed on day 16. Pregnancy loss was observed by day 20 in sheep receiving morpholino antisense oligonucleotides. In vitro inhibition of the enJSRV envelope reduced the proliferation of mononuclear trophectoderm cells isolated from day 15 conceptuses. Consequently, these results demonstrate that the enJSRV envelope regulates trophectoderm growth and differentiation in the periimplantation ovine conceptus. This work supports the hypothesis that ERVs play fundamental roles in placental morphogenesis and mammalian reproduction. PMID:16980413

  15. Economic growth and energy regulation in the environmental Kuznets curve.

    PubMed

    Lorente, Daniel Balsalobre; Álvarez-Herranz, Agustín

    2016-08-01

    This study establishes the existence of a pattern of behavior, between economic growth and environmental degradation, consistent with the environmental Kuznets curve (EKC) hypothesis for 17 Organization for Economic Cooperation and Development (OECD) countries between 1990 and 2012. Based on this EKC pattern, it shows that energy regulation measures help reduce per capita greenhouse gas (GHG) emissions. To validate this hypothesis, we also add the explanatory variables: renewable energy promotion, energy innovation processes, and the suppression effect of income level on the contribution of renewable energy sources to total energy consumption. It aims to be a tool for decision-making regarding energy policy. This paper provides a two-stage econometric analysis of instrumental variables with the aim of correcting the existence of endogeneity in the variable GDP per capita, verifying that the instrumental variables used in this research are appropriate for our aim. To this end, it first makes a methodological contribution before incorporating additional variables associated with environmental air pollution into the EKC hypothesis and showing how they positively affect the explanation of the correction in the GHG emission levels. This study concludes that air pollution will not disappear on its own as economic growth increases. Therefore, it is necessary to promote energy regulation measures to reduce environmental pollution.

  16. HMGB1 mediates hyperglycaemia-induced cardiomyocyte apoptosis via ERK/Ets-1 signalling pathway.

    PubMed

    Wang, Wen-Ke; Lu, Qing-Hua; Zhang, Jia-Ning; Wang, Ben; Liu, Xiang-Juan; An, Feng-Shuang; Qin, Wei-Dong; Chen, Xue-Ying; Dong, Wen-Qian; Zhang, Cheng; Zhang, Yun; Zhang, Ming-Xiang

    2014-11-01

    Apoptosis is a key event involved in diabetic cardiomyopathy. The expression of high mobility group box 1 protein (HMGB1) is up-regulated in diabetic mice. However, the molecular mechanism of high glucose (HG)-induced cardiomyocyte apoptosis remains obscure. We aimed to determine the role of HMGB1 in HG-induced apoptosis of cardiomyocytes. Treating neonatal primary cardiomyocytes with HG increased cell apoptosis, which was accompanied by elevated levels of HMGB1. Inhibition of HMGB1 by short-hairpin RNA significantly decreased HG-induced cell apoptosis by reducing caspase-3 activation and ratio of Bcl2-associated X protein to B-cell lymphoma/leukemia-2 (bax/bcl-2). Furthermore, HG activated E26 transformation-specific sequence-1 (Ets-1), and HMGB1 inhibition attenuated HG-induced activation of Ets-1 via extracellular signal-regulated kinase 1/2 (ERK1/2) signalling. In addition, inhibition of Ets-1 significantly decreased HG-induced cardiomyocyte apoptosis. Similar results were observed in streptozotocin-treated diabetic mice. Inhibition of HMGB1 by short-hairpin RNA markedly decreased myocardial cell apoptosis and activation of ERK and Ets-1 in diabetic mice. In conclusion, inhibition of HMGB1 may protect against hyperglycaemia-induced cardiomyocyte apoptosis by down-regulating ERK-dependent activation of Ets-1.

  17. Isolation and Culture of Neonatal Mouse Cardiomyocytes

    PubMed Central

    Ehler, Elisabeth; Moore-Morris, Thomas; Lange, Stephan

    2013-01-01

    Cultured neonatal cardiomyocytes have long been used to study myofibrillogenesis and myofibrillar functions. Cultured cardiomyocytes allow for easy investigation and manipulation of biochemical pathways, and their effect on the biomechanical properties of spontaneously beating cardiomyocytes. The following 2-day protocol describes the isolation and culture of neonatal mouse cardiomyocytes. We show how to easily dissect hearts from neonates, dissociate the cardiac tissue and enrich cardiomyocytes from the cardiac cell-population. We discuss the usage of different enzyme mixes for cell-dissociation, and their effects on cell-viability. The isolated cardiomyocytes can be subsequently used for a variety of morphological, electrophysiological, biochemical, cell-biological or biomechanical assays. We optimized the protocol for robustness and reproducibility, by using only commercially available solutions and enzyme mixes that show little lot-to-lot variability. We also address common problems associated with the isolation and culture of cardiomyocytes, and offer a variety of options for the optimization of isolation and culture conditions. PMID:24056408

  18. Cardiac Fibroblasts Regulate Sympathetic Nerve Sprouting and Neurocardiac Synapse Stability

    PubMed Central

    Mias, Céline; Coatrieux, Christelle; Denis, Colette; Genet, Gaël; Seguelas, Marie-Hélène; Laplace, Nathalie; Rouzaud-Laborde, Charlotte; Calise, Denis; Parini, Angelo; Cussac, Daniel; Pathak, Atul; Sénard, Jean-Michel; Galés, Céline

    2013-01-01

    Sympathetic nervous system (SNS) plays a key role in cardiac homeostasis and its deregulations always associate with bad clinical outcomes. To date, little is known about molecular mechanisms regulating cardiac sympathetic innervation. The aim of the study was to determine the role of fibroblasts in heart sympathetic innervation. RT-qPCR and western-blots analysis performed in cardiomyocytes and fibroblasts isolated from healthy adult rat hearts revealed that Pro-Nerve growth factor (NGF) and pro-differentiating mature NGF were the most abundant neurotrophins expressed in cardiac fibroblasts while barely detectable in cardiomyocytes. When cultured with cardiac fibroblasts or fibroblast-conditioned medium, PC12 cells differentiated into/sympathetic-like neurons expressing axonal marker Tau-1 at neurites in contact with cardiomyocytes. This was prevented by anti-NGF blocking antibodies suggesting a paracrine action of NGF secreted by fibroblasts. When co-cultured with cardiomyocytes to mimic neurocardiac synapse, differentiated PC12 cells exhibited enhanced norepinephrine secretion as quantified by HPLC compared to PC12 cultured alone while co-culture with fibroblasts had no effect. However, when supplemented to PC12-cardiomyocytes co-culture, fibroblasts allowed long-term survival of the neurocardiac synapse. Activated fibroblasts (myofibroblasts) isolated from myocardial infarction rat hearts exhibited significantly higher mature NGF expression than normal fibroblasts and also promoted PC12 cells differentiation. Within the ischemic area lacking cardiomyocytes and neurocardiac synapses, tyrosine hydroxylase immunoreactivity was increased and associated with local anarchical and immature sympathetic hyperinnervation but tissue norepinephrine content was similar to that of normal cardiac tissue, suggesting depressed sympathetic function. Collectively, these findings demonstrate for the first time that fibroblasts are essential for the setting of cardiac sympathetic

  19. Regulation of rat ovarian cell growth and steroid secretion

    PubMed Central

    Johnson, CC; Dawson, WE; Turner, JT; Wyche, JH

    1980-01-01

    A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin. PMID:6995465

  20. Maternal corticosterone regulates nutrient allocation to fetal growth in mice.

    PubMed

    Vaughan, Owen R; Sferruzzi-Perri, Amanda N; Fowden, Abigail L

    2012-11-01

    Stresses during pregnancy that increase maternal glucocorticoids reduce birth weight in several species. However, the role of natural glucocorticoids in the mother in fetal acquisition of nutrients for growth remains unknown. This study aimed to determine whether fetal growth was reduced as a consequence of altered amino acid supply when mice were given corticosterone in their drinking water for 5 day periods in mid to late pregnancy (day, D, 11-16 or D14-19). Compared to controls drinking tap water, fetal weight was always reduced by corticosterone. At D16, corticosterone had no effect on materno-fetal transfer of [(14)C]methylaminoisobutyric acid (MeAIB), although placental MeAIB accumulation and expression of the Slc38a1 and Slc38a2 transporters were increased. However, at D19, 3 days after treatment ended, materno-fetal transfer of MeAIB was increased by 37% (P < 0.04). During treatment at D19, placental accumulation and materno-fetal transfer of MeAIB were reduced by 40% (P < 0.01), although expression of Slc38a1 was again elevated. Permanent reductions in placental vascularity occurred during the earlier but not the later period of treatment. Placental Hsd11b2 expression, which regulates feto-placental glucocorticoid bioavailability, was also affected by treatment at D19 only. Maternal corticosterone concentrations inversely correlated with materno-fetal MeAIB clearance and fetal weight at D19 but not D16. On D19, weight gain of the maternal carcass was normal during corticosterone treatment but reduced in those mice treated from D11 to D16, in which corticosterone levels were lowest. Maternal corticosterone is, therefore, a physiological regulator of the amino acid supply for fetal growth via actions on placental phenotype.

  1. Maternal corticosterone regulates nutrient allocation to fetal growth in mice

    PubMed Central

    Vaughan, Owen R; Sferruzzi-Perri, Amanda N; Fowden, Abigail L

    2012-01-01

    Stresses during pregnancy that increase maternal glucocorticoids reduce birth weight in several species. However, the role of natural glucocorticoids in the mother in fetal acquisition of nutrients for growth remains unknown. This study aimed to determine whether fetal growth was reduced as a consequence of altered amino acid supply when mice were given corticosterone in their drinking water for 5 day periods in mid to late pregnancy (day, D, 11–16 or D14–19). Compared to controls drinking tap water, fetal weight was always reduced by corticosterone. At D16, corticosterone had no effect on materno-fetal transfer of [14C]methylaminoisobutyric acid (MeAIB), although placental MeAIB accumulation and expression of the Slc38a1 and Slc38a2 transporters were increased. However, at D19, 3 days after treatment ended, materno-fetal transfer of MeAIB was increased by 37% (P < 0.04). During treatment at D19, placental accumulation and materno-fetal transfer of MeAIB were reduced by 40% (P < 0.01), although expression of Slc38a1 was again elevated. Permanent reductions in placental vascularity occurred during the earlier but not the later period of treatment. Placental Hsd11b2 expression, which regulates feto-placental glucocorticoid bioavailability, was also affected by treatment at D19 only. Maternal corticosterone concentrations inversely correlated with materno-fetal MeAIB clearance and fetal weight at D19 but not D16. On D19, weight gain of the maternal carcass was normal during corticosterone treatment but reduced in those mice treated from D11 to D16, in which corticosterone levels were lowest. Maternal corticosterone is, therefore, a physiological regulator of the amino acid supply for fetal growth via actions on placental phenotype. PMID:22930269

  2. Regulation of growth hormone secretion by (pro)renin receptor.

    PubMed

    Tani, Yuji; Yamada, Shozo; Inoshita, Naoko; Hirata, Yukio; Shichiri, Masayoshi

    2015-06-03

    (Pro)renin receptor (PRR) has a single transmembrane domain that co-purifies with the vacuolar H(+)-ATPase (V-ATPase). In addition to its role in cellular acidification, V-ATPase has been implicated in membrane fusion and exocytosis via its Vo domain. Results from the present study show that PRR is expressed in pituitary adenoma cells and regulates growth hormone (GH) release via V-ATPase-induced cellular acidification. Positive PRR immunoreactivity was detected more often in surgically resected, growth hormone-producing adenomas (GHomas) than in nonfunctional pituitary adenomas. GHomas strongly expressing PRR showed excess GH secretion, as evidenced by distinctly high plasma GH and insulin-like growth factor-1 levels, as well as an elevated nadir GH in response to the oral glucose tolerance test. Suppression of PRR expression in rat GHoma-derived GH3 cells using PRR siRNA resulted in reduced GH secretion and significantly enhanced intracellular GH accumulation. GH3 treatment with bafilomycin A1, a V-ATPase inhibitor, also blocked GH release, indicating mediation via impaired cellular acidification of V-ATPase. PRR knockdown decreased Atp6l, a subunit of the Vo domain that destabilizes V-ATPase assembly, increased intracellular GH, and decreased GH release. To our knowledge, this is the first report demonstrating a pivotal role for PRR in a pituitary hormone release mechanism.

  3. [Breast hormones--regulators of energy homeostasis: growth of infants].

    PubMed

    Kon', I Ia; Shilina, N M; Gmoshinskaia, M V; Ivanushkina, T A

    2011-01-01

    Studied the possible relationship between the growth rate of children who are breastfed, and the level of protein, fat, insulin-like growth factor- 1 (IGF-1), ghrelin, leptin, adiponectin in breast milk. Examined 71 pair--a mother and a healthy child, who is breastfed. All infants were divided into 3 groups: low, normal and high weight gain. Daily breast milk intake, the level of fat, protein and hormones proteins regulators of energy homeostasis (adiponectin, grelin, IGF-1 and leptin) in breast milk were measured at 1, 2 and 3 months of lactation. It was found that daily breast milk consumption was higher in the group of infants with high weight gain and the content of protein and fat in it did not differ in three groups. Total daily consumption of protein and fat with breast milk was higher in groups of infants with high weight gain. There was significantly higher IGF-1 level and the tendency to higher grelin level in breast milk of mothers of infants with higher weight gain. The possible link of breast milk hormones with growth velocity of breast-fed infants is discussed.

  4. ARNT2 Regulates Tumoral Growth in Oral Squamous Cell Carcinoma

    PubMed Central

    Kimura, Yasushi; Kasamatsu, Atsushi; Nakashima, Dai; Yamatoji, Masanobu; Minakawa, Yasuyuki; Koike, Kazuyuki; Fushimi, Kazuaki; Higo, Morihiro; Endo-Sakamoto, Yosuke; Shiiba, Masashi; Tanzawa, Hideki; Uzawa, Katsuhiro

    2016-01-01

    Aryl hydrocarbon receptor nuclear translocator (ARNT) 2 is a transcriptional factor related to adaptive responses against cellular stress from a xenobiotic substance. Recent evidence indicates ARNT is involved in carcinogenesis and cancer progression; however, little is known about the relevance of ARNT2 in the behavior of oral squamous cell carcinoma (OSCC). In the current study, we evaluated the ARNT2 mRNA and protein expression levels in OSCC in vitro and in vivo and the clinical relationship between ARNT2 expression levels in primary OSCCs and their clinicopathologic status by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemistry. Using ARNT2 overexpression models, we performed functional analyses to investigate the critical roles of ARNT2 in OSCC. ARNT2 mRNA and protein were down-regulated significantly (P < 0.05 for both comparisons) in nine OSCC-derived cells and primary OSCC (n=100 patients) compared with normal counterparts. In addition to the data from exogenous experiments that ARNT2-overexpressed cells showed decreased cellular proliferation, ARNT2-positive OSCC cases were correlated significantly (P < 0.05) with tumoral size. Since von Hippel-Lindau tumor suppressor, E3 ubiquitin protein ligase, a negative regulator of hypoxia-inducible factor (HIF1)-α, is a downstream molecule of ARNT2, we speculated that HIF1-α and its downstream molecules would have key functions in cellular growth. Consistent with our hypothesis, overexpressed ARNT2 cells showed down-regulation of HIF1-α, which causes hypofunctioning of glucose transporter 1, leading to decreased cellular growth. Our results proposed for the first time that the ARNT2 level is an indicator of cellular proliferation in OSCCs. Therefore, ARNT2 may be a potential therapeutic target against progression of OSCCs. PMID:27076852

  5. Role of Histone Demethylases in Cardiomyocytes Induced to Hypertrophy

    PubMed Central

    Carulla, Juan; García, Jeison

    2016-01-01

    Epigenetic changes induced by histone demethylases play an important role in differentiation and pathological changes in cardiac cells. However, the role of the jumonji family of demethylases in the development of cardiac hypertrophy remains elusive. In this study, the presence of different histone demethylases in cardiac cells was evaluated after hypertrophy was induced with neurohormones. A cell line from rat cardiomyocytes was used as a biological model. The phenotypic profiles of the cells, as well as the expression of histone demethylases, were studied through immunofluorescence, transient transfection, western blot, and qRT-PCR analysis after inducing hypertrophy by angiotensin II and endothelin-1. An increase in fetal gene expression (ANP, BNP, and β-MHC) was observed in cardiomyocytes after treatment with angiotensin II and endothelin-1. A significant increase in JMJD2A expression, but not in UTX or JMJD2C expression, was observed. When JMJD2A was overexpressed in cardiomyocytes through transient transfection, the effect of neurohormones on fetal cardiac gene expression was increased. We conclude that JMJD2A plays a principal role in the regulation of fetal cardiac genes, which increase in expression during the pathological hypertrophic process. PMID:27722168

  6. Mkk4 Is a Negative Regulator of the Transforming Growth Factor Beta 1 Signaling Associated With Atrial Remodeling and Arrhythmogenesis With Age

    PubMed Central

    Davies, Laura; Jin, Jiawei; Shen, Weijin; Tsui, Hoyee; Shi, Ying; Wang, Yanwen; Zhang, Yanmin; Hao, Guoliang; Wu, Jingjing; Chen, Si; Fraser, James A.; Dong, Nianguo; Christoffels, Vincent; Ravens, Ursula; Huang, Christopher L.‐H.; Zhang, Henggui; Cartwright, Elizabeth J.; Wang, Xin; Lei, Ming

    2014-01-01

    Background Atrial fibrillation (AF), often associated with structural, fibrotic change in cardiac tissues involving regulatory signaling mediators, becomes increasingly common with age. In the present study, we explored the role of mitogen‐activated protein kinase kinase 4 (Mkk4), a critical component of the stress‐activated mitogen‐activated protein kinase family, in age‐associated AF. Methods and Results We developed a novel mouse model with a selective inactivation of atrial cardiomyocyte Mkk4 (Mkk4ACKO). We characterized and compared electrophysiological, histological, and molecular features of young (3‐ to 4‐month), adult (6‐month), and old (1‐year) Mkk4ACKO mice with age‐matched control littermates (Mkk4F/F). Aging Mkk4ACKO mice were more susceptible to atrial tachyarrhythmias than the corresponding Mkk4F/F mice, showing characteristic slow and dispersed atrial conduction, for which modeling studies demonstrated potential arrhythmic effects. These differences paralleled increased interstitial fibrosis, upregulated transforming growth factor beta 1 (TGF‐β1) signaling and dysregulation of matrix metalloproteinases in Mkk4ACKO, compared to Mkk4F/F, atria. Mkk4 inactivation increased the sensitivity of cultured cardiomyocytes to angiotensin II–induced activation of TGF‐β1 signaling. This, in turn, enhanced expression of profibrotic molecules in cultured cardiac fibroblasts, suggesting cross‐talk between these two cell types in profibrotic signaling. Finally, human atrial tissues in AF showed a Mkk4 downregulation associated with increased production of profibrotic molecules, compared to findings in tissue from control subjects in sinus rhythm. Conclusions These findings together demonstrate, for the first time, that Mkk4 is a negative regulator of the TGF‐β1 signaling associated with atrial remodeling and arrhythmogenesis with age, establishing Mkk4 as a new potential therapeutic target for treating AF. PMID:24721794

  7. A Repressor Protein Complex Regulates Leaf Growth in Arabidopsis

    PubMed Central

    Gonzalez, Nathalie; Pauwels, Laurens; Baekelandt, Alexandra; De Milde, Liesbeth; Van Leene, Jelle; Besbrugge, Nienke; Heyndrickx, Ken S.; Pérez, Amparo Cuéllar; Durand, Astrid Nagels; De Clercq, Rebecca; Van De Slijke, Eveline; Vanden Bossche, Robin; Eeckhout, Dominique; Gevaert, Kris; Vandepoele, Klaas; De Jaeger, Geert; Goossens, Alain; Inzé, Dirk

    2015-01-01

    Cell number is an important determinant of final organ size. In the leaf, a large proportion of cells are derived from the stomatal lineage. Meristemoids, which are stem cell-like precursor cells, undergo asymmetric divisions, generating several pavement cells adjacent to the two guard cells. However, the mechanism controlling the asymmetric divisions of these stem cells prior to differentiation is not well understood. Here, we characterized PEAPOD (PPD) proteins, the only transcriptional regulators known to negatively regulate meristemoid division. PPD proteins interact with KIX8 and KIX9, which act as adaptor proteins for the corepressor TOPLESS. D3-type cyclin encoding genes were identified among direct targets of PPD2, being negatively regulated by PPDs and KIX8/9. Accordingly, kix8 kix9 mutants phenocopied PPD loss-of-function producing larger leaves resulting from increased meristemoid amplifying divisions. The identified conserved complex might be specific for leaf growth in the second dimension, since it is not present in Poaceae (grasses), which also lack the developmental program it controls. PMID:26232487

  8. Regulation of skeletal muscle stem cells by fibroblast growth factors.

    PubMed

    Pawlikowski, Bradley; Vogler, Thomas Orion; Gadek, Katherine; Olwin, Bradley B

    2017-03-01

    Fibroblast growth factors (FGFs) are essential for self-renewal of skeletal muscle stem cells (satellite cells) and required for maintenance and repair of skeletal muscle. Satellite cells express high levels of FGF receptors 1 and 4, low levels of FGF receptor 3, and little or no detectable FGF receptor 2. Of the multiple FGFs that influence satellite cell function in culture, FGF2 and FGF6 are the only members that regulate satellite cell function in vivo by activating ERK MAPK, p38α/β MAPKs, PI3 kinase, PLCγ and STATs. Regulation of FGF signaling is complex in satellite cells, requiring Syndecan-4, a heparan sulfate proteoglycan, as well as ß1-integrin and fibronectin. During aging, reduced responsiveness to FGF diminishes satellite cell self-renewal, leading to impaired skeletal muscle regeneration and depletion of satellite cells. Mislocalization of ß1-integrin, reductions in fibronectin, and alterations in heparan sulfate content all contribute to reduced FGF responsiveness in satellite cells. How these cell surface proteins regulate satellite cell self-renewal is incompletely understood. Here we summarize the current knowledge, highlighting the role(s) for FGF signaling in skeletal muscle regeneration, satellite cell behavior, and age-induced muscle wasting. Developmental Dynamics, 2017. © 2017 Wiley Periodicals, Inc.

  9. Evidence for a Critical Role of Catecholamines for Cardiomyocyte Lineage Commitment in Murine Embryonic Stem Cells

    PubMed Central

    Lehmann, Martin; Nguemo, Filomain; Wagh, Vilas; Pfannkuche, Kurt; Hescheler, Jürgen; Reppel, Michael

    2013-01-01

    Catecholamine release is known to modulate cardiac output by increasing heart rate. Although much is known about catecholamine function and regulation in adults, little is known about the presence and role of catecholamines during heart development. The present study aimed therefore to evaluate the effects of different catecholamines on early heart development in an in vitro setting using embryonic stem (ES) cell-derived cardiomyocytes. Effects of catecholamine depletion induced by reserpine were examined in murine ES cells (line D3, αPIG44) during differentiation. Cardiac differentiation was assessed by immunocytochemistry, qRT-PCR, quantification of beating clusters, flow cytometry and pharmacological approaches. Proliferation was analyzed by EB cross-section measurements, while functionality of cardiomyocytes was studied by extracellular field potential (FP) measurements using microelectrode arrays (MEAs). To further differentiate between substance-specific effects of reserpine and catecholamine action via α- and β-receptors we proved the involvement of adrenergic receptors by application of unspecific α- and β-receptor antagonists. Reserpine treatment led to remarkable down-regulation of cardiac-specific genes, proteins and mesodermal marker genes. In more detail, the average ratio of ∼40% spontaneously beating control clusters was significantly reduced by 100%, 91.1% and 20.0% on days 10, 12, and 14, respectively. Flow cytometry revealed a significant reduction (by 71.6%, n = 11) of eGFP positive CMs after reserpine treatment. By contrast, reserpine did not reduce EB growth while number of neuronal cells in reserpine-treated EBs was significantly increased. MEA measurements of reserpine-treated EBs showed lower FP frequencies and weak responsiveness to adrenergic and muscarinic stimulation. Interestingly we found that developmental inhibition after α- and β-adrenergic blocker application mimicked developmental changes with reserpine. Using several

  10. Juvenile hormone regulates extreme mandible growth in male stag beetles.

    PubMed

    Gotoh, Hiroki; Cornette, Richard; Koshikawa, Shigeyuki; Okada, Yasukazu; Lavine, Laura Corley; Emlen, Douglas J; Miura, Toru

    2011-01-01

    The morphological diversity of insects is one of the most striking phenomena in biology. Evolutionary modifications to the relative sizes of body parts, including the evolution of traits with exaggerated proportions, are responsible for a vast range of body forms. Remarkable examples of an insect trait with exaggerated proportions are the mandibular weapons of stag beetles. Male stag beetles possess extremely enlarged mandibles which they use in combat with rival males over females. As with other sexually selected traits, stag beetle mandibles vary widely in size among males, and this variable growth results from differential larval nutrition. However, the mechanisms responsible for coupling nutrition with growth of stag beetle mandibles (or indeed any insect structure) remain largely unknown. Here, we demonstrate that during the development of male stag beetles (Cyclommatus metallifer), juvenile hormone (JH) titers are correlated with the extreme growth of an exaggerated weapon of sexual selection. We then investigate the putative role of JH in the development of the nutritionally-dependent, phenotypically plastic mandibles, by increasing hemolymph titers of JH with application of the JH analog fenoxycarb during larval and prepupal developmental periods. Increased JH signaling during the early prepupal period increased the proportional size of body parts, and this was especially pronounced in male mandibles, enhancing the exaggerated size of this trait. The direction of this response is consistent with the measured JH titers during this same period. Combined, our results support a role for JH in the nutrition-dependent regulation of extreme mandible growth in this species. In addition, they illuminate mechanisms underlying the evolution of trait proportion, the most salient feature of the evolutionary diversification of the insects.

  11. Molecular Characterization of Striated Muscle-Specific Gab1 Isoform as a Critical Signal Transducer for Neuregulin-1/ErbB Signaling in Cardiomyocytes

    PubMed Central

    Yasui, Taku; Masaki, Takeshi; Arita, Yoh; Ishibashi, Tomohiko; Inagaki, Tadakatsu; Okazawa, Makoto; Oka, Toru; Shioyama, Wataru; Yamauchi-Takihara, Keiko; Komuro, Issei; Sakata, Yasushi; Nakaoka, Yoshikazu

    2016-01-01

    Grb2-associated binder (Gab) docking proteins regulate signals downstream of a variety of growth factors and receptor tyrosine kinases. Neuregulin-1 (NRG-1), a member of epidermal growth factor family, plays a critical role for cardiomyocyte proliferation and prevention of heart failure via ErbB receptors. We previously reported that Gab1 and Gab2 in the myocardium are essential for maintenance of myocardial function in the postnatal heart via transmission of NRG-1/ErbB-signaling through analysis of Gab1/Gab2 cardiomyocyte-specific double knockout mice. In that study, we also found that there is an unknown high-molecular weight (high-MW) Gab1 isoform (120 kDa) expressed exclusively in the heart, in addition to the ubiquitously expressed low-MW (100 kDa) Gab1. However, the high-MW Gab1 has been molecularly ill-defined to date. Here, we identified the high-MW Gab1 as a striated muscle-specific isoform. The high-MW Gab1 has an extra exon encoding 27 amino acid residues between the already-known 3rd and 4th exons of the ubiquitously expressed low-MW Gab1. Expression analysis by RT-PCR and immunostaining with the antibody specific for the high-MW Gab1 demonstrate that the high-MW Gab1 isoform is exclusively expressed in striated muscle including heart and skeletal muscle. The ratio of high-MW Gab1/ total Gab1 mRNAs increased along with heart development. The high-MW Gab1 isoform in heart underwent tyrosine-phosphorylation exclusively after intravenous administration of NRG-1, among several growth factors. Adenovirus-mediated overexpression of the high-MW Gab1 induces more sustained activation of AKT after stimulation with NRG-1 in cardiomyocytes compared with that of β-galactosidase. On the contrary, siRNA-mediated knockdown of the high-MW Gab1 significantly attenuated AKT activation after stimulation with NRG-1 in cardiomyocytes. Taken together, these findings suggest that the striated muscle-specific high-MW isoform of Gab1 has a crucial role for NRG-1/ErbB signaling

  12. Disruption of a GATA4/Ankrd1 signaling axis in cardiomyocytes leads to sarcomere disarray: implications for anthracycline cardiomyopathy.

    PubMed

    Chen, Billy; Zhong, Lin; Roush, Sarah F; Pentassuglia, Laura; Peng, Xuyang; Samaras, Susan; Davidson, Jeffrey M; Sawyer, Douglas B; Lim, Chee Chew

    2012-01-01

    Doxorubicin (Adriamycin) is an effective anti-cancer drug, but its clinical usage is limited by a dose-dependent cardiotoxicity characterized by widespread sarcomere disarray and loss of myofilaments. Cardiac ankyrin repeat protein (CARP, ANKRD1) is a transcriptional regulatory protein that is extremely susceptible to doxorubicin; however, the mechanism(s) of doxorubicin-induced CARP depletion and its specific role in cardiomyocytes have not been completely defined. We report that doxorubicin treatment in cardiomyocytes resulted in inhibition of CARP transcription, depletion of CARP protein levels, inhibition of myofilament gene transcription, and marked sarcomere disarray. Knockdown of CARP with small interfering RNA (siRNA) similarly inhibited myofilament gene transcription and disrupted cardiomyocyte sarcomere structure. Adenoviral overexpression of CARP, however, was unable to rescue the doxorubicin-induced sarcomere disarray phenotype. Doxorubicin also induced depletion of the cardiac transcription factor GATA4 in cardiomyocytes. CARP expression is regulated in part by GATA4, prompting us to examine the relationship between GATA4 and CARP in cardiomyocytes. We show in co-transfection experiments that GATA4 operates upstream of CARP by activating the proximal CARP promoter. GATA4-siRNA knockdown in cardiomyocytes inhibited CARP expression and myofilament gene transcription, and induced extensive sarcomere disarray. Adenoviral overexpression of GATA4 (AdV-GATA4) in cardiomyocytes prior to doxorubicin exposure maintained GATA4 levels, modestly restored CARP levels, and attenuated sarcomere disarray. Interestingly, siRNA-mediated depletion of CARP completely abolished the Adv-GATA4 rescue of the doxorubicin-induced sarcomere phenotype. These data demonstrate co-dependent roles for GATA4 and CARP in regulating sarcomere gene expression and maintaining sarcomeric organization in cardiomyocytes in culture. The data further suggests that concurrent depletion of GATA4

  13. Proepithelin Regulates Prostate Cancer Cell Biology by Promoting Cell Growth, Migration, and Anchorage-Independent Growth

    PubMed Central

    Monami, Giada; Emiliozzi, Velia; Bitto, Alessandro; Lovat, Francesca; Xu, Shi-Qiong; Goldoni, Silvia; Fassan, Matteo; Serrero, Ginette; Gomella, Leonard G.; Baffa, Raffaele; Iozzo, Renato V.; Morrione, Andrea

    2009-01-01

    The growth factor proepithelin has recently emerged as an important regulator of transformation in several physiological and pathological systems. In this study, we determined the biological roles of proepithelin in prostate cancer cells using purified human recombinant proepithelin as well as proepithelin-depletion strategies. Proepithelin promoted the migration of androgen-dependent and -independent human prostate cancer cells; androgen-independent DU145 cells were the more responsive. In these cells, proepithelin additionally stimulated wound closure, invasion, and promotion of cell growth in vitro. These effects required the activation of both the Akt and mitogen-activated protein kinase pathways. We have analyzed proepithelin expression levels in different available prostate cancer microarray studies using the Oncomine database and found a statistically significant increase in proepithelin mRNA expression levels in prostate cancers compared with nonneoplastic controls. Notably, depletion of endogenous proepithelin by siRNA and antisense strategies impaired the ability of DU145 cells to grow and migrate after serum withdrawal and inhibited anchorage-independent growth. Our results provide the first evidence for a role of proepithelin in stimulating the migration, invasion, proliferation, and anchorage-independent growth of prostate cancer cells. This study supports the hypothesis that proepithelin may play a critical role as an autocrine growth factor in the establishment and initial progression of prostate cancer. Furthermore, proepithelin may prove to be a useful clinical marker for the diagnosis of prostate tumors. PMID:19179604

  14. Controlled-release systems for the insect growth regulator pyriproxyfen.

    PubMed

    Schwartz, Liliana; Wolf, David; Markus, Arie; Wybraniec, Sławomir; Wiesman, Zeev

    2003-09-24

    A simple technique was developed for the production of controlled-release systems (CRSs) for pyriproxyfen, an insect growth regulator active against the larvae of Culex pipiens, the most common species of mosquito found in developed countries. The CRSs consisted of a spongy core material encapsulated in a coating of a polyurethane or polyurea hydrogel, into which the active ingredient had been incorporated. The coating also included a surfactant to improve the low solubility in water of pyriproxyfen. The light core material enabled the CRS to float on the water surface, where the mosquitoe larvae are found. The type and amount of the polymeric coating and the amount of surfactant influenced the release profiles into water of the active ingredient. The release profiles of the CRSs were adjusted to the life cycle of the C. pipiens mosquito in order to obtain their optimal activity on the eighth day, which corresponds to the time of larval maturity.

  15. Mesenchymal stem cell-cardiomyocyte interactions under defined contact modes on laser-patterned biochips.

    PubMed

    Ma, Zhen; Yang, Huaxiao; Liu, Honghai; Xu, Meifeng; Runyan, Raymond B; Eisenberg, Carol A; Markwald, Roger R; Borg, Thomas K; Gao, Bruce Z

    2013-01-01

    Understanding how stem cells interact with cardiomyocytes is crucial for cell-based therapies to restore the cardiomyocyte loss that occurs during myocardial infarction and other cardiac diseases. It has been thought that functional myocardial repair and regeneration could be regulated by stem cell-cardiomyocyte contact. However, because various contact modes (junction formation, cell fusion, partial cell fusion, and tunneling nanotube formation) occur randomly in a conventional coculture system, the particular regulation corresponding to a specific contact mode could not be analyzed. In this study, we used laser-patterned biochips to define cell-cell contact modes for systematic study of contact-mediated cellular interactions at the single-cell level. The results showed that the biochip design allows defined stem cell-cardiomyocyte contact-mode formation, which can be used to determine specific cellular interactions, including electrical coupling, mechanical coupling, and mitochondria transfer. The biochips will help us gain knowledge of contact-mediated interactions between stem cells and cardiomyocytes, which are fundamental for formulating a strategy to achieve stem cell-based cardiac tissue regeneration.

  16. Hypertrophy changes 3D shape of hiPSC-cardiomyocytes: Implications for cellular maturation in regenerative medicine.

    PubMed

    Rupert, Cassady E; Chang, Heidi H; Coulombe, Kareen L K

    2017-02-01

    Advances in the use of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes for heart regeneration and in vitro disease models demand a greater understanding of how these cells grow and mature in 3-dimensional space. In this study, we developed an analysis methodology of single cardiomyocytes plated on 2D surfaces to assess their 3D myofilament volume and its z-height distribution, or shape, upon hypertrophic stimulation via phenylephrine (PE) treatment or long-term culture ("aging"). Cardiomyocytes were fixed and labeled with α-actinin for confocal microscopy imaging to obtain z-stacks for 3D myofilament volume analysis. In primary neonatal rat ventricular myocytes (NRVMs), area increased 72% with PE, while volume increased 31%. In hiPSC-cardiomyocytes, area increased 70% with PE and 4-fold with aging; however, volume increased significantly only with aging by 2.3-fold. Analysis of z-height myofilament volume distribution in hiPSC-cardiomyocytes revealed a shift from a fairly uniform distribution in control cells to a basally located volume in a more flat and spread morphology with PE and even more so with aging, a shape that was akin to all NRVMs analyzed. These results suggest that 2D area is not a sufficient measure of hiPSC-cardiomyocyte growth and maturation, and that changes in 3D volume and its distribution are essential for understanding hiPSC-cardiomyocyte biology for disease modeling and regenerative medicine applications.

  17. Triiodothyronine regulates cell growth and survival in renal cell cancer.

    PubMed

    Czarnecka, Anna M; Matak, Damian; Szymanski, Lukasz; Czarnecka, Karolina H; Lewicki, Slawomir; Zdanowski, Robert; Brzezianska-Lasota, Ewa; Szczylik, Cezary

    2016-10-01

    Triiodothyronine plays an important role in the regulation of kidney cell growth, differentiation and metabolism. Patients with renal cell cancer who develop hypothyreosis during tyrosine kinase inhibitor (TKI) treatment have statistically longer survival. In this study, we developed cell based model of triiodothyronine (T3) analysis in RCC and we show the different effects of T3 on renal cell cancer (RCC) cell growth response and expression of the thyroid hormone receptor in human renal cell cancer cell lines from primary and metastatic tumors along with human kidney cancer stem cells. Wild-type thyroid hormone receptor is ubiquitously expressed in human renal cancer cell lines, but normalized against healthy renal proximal tube cell expression its level is upregulated in Caki-2, RCC6, SKRC-42, SKRC-45 cell lines. On the contrary the mRNA level in the 769-P, ACHN, HKCSC, and HEK293 cells is significantly decreased. The TRβ protein was abundant in the cytoplasm of the 786-O, Caki-2, RCC6, and SKRC-45 cells and in the nucleus of SKRC-42, ACHN, 769-P and cancer stem cells. T3 has promoting effect on the cell proliferation of HKCSC, Caki-2, ASE, ACHN, SK-RC-42, SMKT-R2, Caki-1, 786-0, and SK-RC-45 cells. Tyrosine kinase inhibitor, sunitinib, directly inhibits proliferation of RCC cells, while thyroid hormone receptor antagonist 1-850 (CAS 251310‑57-3) has less significant inhibitory impact. T3 stimulation does not abrogate inhibitory effect of sunitinib. Renal cancer tumor cells hypostimulated with T3 may be more responsive to tyrosine kinase inhibition. Moreover, some tumors may be considered as T3-independent and present aggressive phenotype with thyroid hormone receptor activated independently from the ligand. On the contrary proliferation induced by deregulated VHL and or c-Met pathways may transgress normal T3 mediated regulation of the cell cycle.

  18. Cytoprotective and Cytotoxic Effects of Rice Bran Extracts in Rat H9c2(2-1) Cardiomyocytes

    PubMed Central

    Tan, Xian Wen; Bhave, Mrinal; Fong, Alan Yean Yip; Matsuura, Eiji; Kobayashi, Kazuko; Shen, Lian Hua; Hwang, Siaw San

    2016-01-01

    This study was aimed at preliminarily assessing the cytoprotective and antioxidative effects of rice bran extracts (RBEs) from a Sarawak local rice variety (local name: “BJLN”) and a commercial rice variety, “MR219,” on oxidative stress in rat H9c2(2-1) cardiomyocytes. The cardiomyocytes were incubated with different concentrations of RBE and hydrogen peroxide (H2O2), respectively, to identify their respective IC50 values and safe dose ranges. Two nonlethal and close-to-IC50 doses of RBE were selected to evaluate their respective effects on H2O2 induced oxidative stress in cardiomyocytes. Both RBEs showed dose-dependent cytotoxicity effects on cardiomyocytes. H2O2 induction of cardiomyocytes pretreated with RBE further revealed the dose-dependent cytoprotective and antioxidative effects of RBE via an increase in IC50 values of H2O2. Preliminary analyses of induction effects of RBE and H2O2 on cellular antioxidant enzyme, catalase (CAT), also revealed their potential in regulating these activities and expression profile of related gene on oxidative stress in cardiomyocytes. Pretreated cardiomyocytes significantly upregulated the enzymatic activity and expression level of CAT under the exposure of H2O2 induced oxidative stress. This preliminary study has demonstrated the potential antioxidant effects of RBE in alleviating H2O2-mediated oxidative injuries via upregulation in enzymatic activities and expression levels of CAT. PMID:27239253

  19. CDK9 and its repressor LARP7 modulate cardiomyocyte proliferation and response to injury in the zebrafish heart

    PubMed Central

    Matrone, Gianfranco; Wilson, Kathryn S.; Maqsood, Sana; Mullins, John J.; Tucker, Carl S.; Denvir, Martin A.

    2015-01-01

    ABSTRACT Cyclin dependent kinase (Cdk)9 acts through the positive transcription elongation factor-b (P-TEFb) complex to activate and expand transcription through RNA polymerase II. It has also been shown to regulate cardiomyocyte hypertrophy, with recent evidence linking it to cardiomyocyte proliferation. We hypothesised that modification of CDK9 activity could both impair and enhance the cardiac response to injury by modifying cardiomyocyte proliferation. Cdk9 expression and activity were inhibited in the zebrafish (Danio rerio) embryo. We show that dephosphorylation of residue Ser2 on the C-terminal domain of RNA polymerase II is associated with impaired cardiac structure and function, and cardiomyocyte proliferation and also results in impaired functional recovery following cardiac laser injury. In contrast, de-repression of Cdk9 activity, through knockdown of La-related protein (Larp7) increases phosphorylation of Ser2 in RNA polymerase II and increases cardiomyocyte proliferation. Larp7 knockdown rescued the structural and functional phenotype associated with knockdown of Cdk9. The balance of Cdk9 and Larp7 plays a key role in cardiomyocyte proliferation and response to injury. Larp7 represents a potentially novel therapeutic target to promote cardiomyocyte proliferation and recovery from injury. PMID:26542022

  20. ATG16L1 phosphorylation is oppositely regulated by CSNK2/casein kinase 2 and PPP1/protein phosphatase 1 which determines the fate of cardiomyocytes during hypoxia/reoxygenation

    PubMed Central

    Song, Huiwen; Pu, Jun; Wang, Lin; Wu, Lihua; Xiao, Jianmin; Liu, Qigong; Chen, Jun; Zhang, Min; Liu, Yang; Ni, Mingke; Mo, Jinggang; Zheng, Yunliang; Wan, Deli; Cai, XiongJiu; Cao, Yaping; Xiao, Weiyi; Ye, Lei; Tu, Enyuan; Lin, Zhihai; Wen, Jianxin; Lu, Xiaoling; He, Jian; Peng, Yi; Su, Jing; Zhang, Heng; Zhao, Yongxiang; Lin, Meihua; Zhang, Zhiyong

    2015-01-01

    Recent studies have shown that the phosphorylation and dephosphorylation of ULK1 and ATG13 are related to autophagy activity. Although ATG16L1 is absolutely required for autophagy induction by affecting the formation of autophagosomes, the post-translational modification of ATG16L1 remains elusive. Here, we explored the regulatory mechanism and role of ATG16L1 phosphorylation for autophagy induction in cardiomyocytes. We showed that ATG16L1 was a phosphoprotein, because phosphorylation of ATG16L1 was detected in rat cardiomyocytes during hypoxia/reoxygenation (H/R). We not only demonstrated that CSNK2 (casein kinase 2) phosphorylated ATG16L1, but also identified the highly conserved Ser139 as the critical phosphorylation residue for CSNK2. We further established that ATG16L1 associated with the ATG12-ATG5 complex in a Ser139 phosphorylation-dependent manner. In agreement with this finding, CSNK2 inhibitor disrupted the ATG12-ATG5-ATG16L1 complex. Importantly, phosphorylation of ATG16L1 on Ser139 was responsible for H/R-induced autophagy in cardiomyocytes, which protects cardiomyocytes from apoptosis. Conversely, we determined that wild-type PPP1 (protein phosphatase 1), but not the inactive mutant, associated with ATG16L1 and antagonized CSNK2-mediated phosphorylation of ATG16L1. Interestingly, one RVxF consensus site for PPP1 binding in the C-terminal tail of ATG16L1 was identified; mutation of this site disrupted its association with ATG16L1. Notably, CSNK2 also associated with PPP1, but ATG16L1 depletion impaired the interaction between CSNK2 and PPP1. Collectively, these data identify ATG16L1 as a bona fide physiological CSNK2 and PPP1 substrate, which reveals a novel molecular link from CSNK2 to activation of the autophagy-specific ATG12-ATG5-ATG16L1 complex and autophagy induction. PMID:26083323

  1. Light regulation of the growth response in corn root gravitropism

    NASA Technical Reports Server (NTRS)

    Kelly, M. O.; Leopold, A. C.

    1992-01-01

    Roots of Merit variety corn (Zea mays L.) require red light for orthogravitropic curvature. Experiments were undertaken to identify the step in the pathway from gravity perception to asymmetric growth on which light may act. Red light was effective in inducing gravitropism whether it was supplied concomitant with or as long as 30 minutes after the gravity stimulus (GS). The presentation time was the same whether the GS was supplied in red light or in darkness. Red light given before the GS slightly enhanced the rate of curvature but had little effect on the lag time or on the final curvature. This enhancement was expanded by a delay between the red light pulse and the GS. These results indicate that gravity perception and at least the initial transduction steps proceed in the dark. Light may regulate the final growth (motor) phase of gravitropism. The time required for full expression of the light enhancement of curvature is consistent with its involvement in some light-stimulated biosynthetic event.

  2. Computational insight into the chemical space of plant growth regulators.

    PubMed

    Bushkov, Nikolay A; Veselov, Mark S; Chuprov-Netochin, Roman N; Marusich, Elena I; Majouga, Alexander G; Volynchuk, Polina B; Shumilina, Daria V; Leonov, Sergey V; Ivanenkov, Yan A

    2016-02-01

    An enormous technological progress has resulted in an explosive growth in the amount of biological and chemical data that is typically multivariate and tangled in structure. Therefore, several computational approaches have mainly focused on dimensionality reduction and convenient representation of high-dimensional datasets to elucidate the relationships between the observed activity (or effect) and calculated parameters commonly expressed in terms of molecular descriptors. We have collected the experimental data available in patent and scientific publications as well as specific databases for various agrochemicals. The resulting dataset was then thoroughly analyzed using Kohonen-based self-organizing technique. The overall aim of the presented study is to investigate whether the developed in silico model can be applied to predict the agrochemical activity of small molecule compounds and, at the same time, to offer further insights into the distinctive features of different agrochemical categories. The preliminary external validation with several plant growth regulators demonstrated a relatively high prediction power (67%) of the constructed model. This study is, actually, the first example of a large-scale modeling in the field of agrochemistry.

  3. Symbiotic regulation of plant growth, development and reproduction

    USGS Publications Warehouse

    Rodriguez, R.J.; Freeman, D. Carl; McArthur, E.D.; Kim, Y.-O.; Redman, R.S.

    2009-01-01

    The growth and development of rice (Oryzae sativa) seedlings was shown to be regulated epigenetically by a fungal endophyte. In contrast to un-inoculated (nonsymbiotic) plants, endophyte colonized (symbiotic) plants preferentially allocated resources into root growth until root hairs were well established. During that time symbiotic roots expanded at five times the rate observed in nonsymbiotic plants. Endophytes also influenced sexual reproduction of mature big sagebrush (Artemisia tridentata) plants. Two spatially distinct big sagebrush subspecies and their hybrids were symbiotic with unique fungal endophytes, despite being separated by only 380 m distance and 60 m elevation. A double reciprocal transplant experiment of parental and hybrid plants, and soils across the hybrid zone showed that fungal endophytes interact with the soils and different plant genotypes to confer enhanced plant reproduction in soil native to the endophyte and reduced reproduction in soil alien to the endophyte. Moreover, the most prevalent endophyte of the hybrid zone reduced the fitness of both parental subspecies. Because these endophytes are passed to the next generation of plants on seed coats, this interaction provides a selective advantage, habitat specificity, and the means of restricting gene flow, thereby making the hybrid zone stable, narrow and potentially leading to speciation. ?? 2009 Landes Bioscience.

  4. Epidermal Growth Factor Regulates Hematopoietic Regeneration Following Radiation Injury

    PubMed Central

    Doan, Phuong L.; Himburg, Heather A.; Helms, Katherine; Russell, J. Lauren; Fixsen, Emma; Quarmyne, Mamle; Harris, Jeffrey R.; Deoliviera, Divino; Sullivan, Julie M.; Chao, Nelson J.; Kirsch, David G.; Chute, John P.

    2013-01-01

    The mechanisms which regulate HSC regeneration following myelosuppressive injury are not well understood. We identified epidermal growth factor (EGF) to be highly enriched in the bone marrow (BM) serum of mice bearing deletion of Bak and Bax in Tie2+ cells (Tie2Cre;Bak1−/−;Baxfl/− mice), which displayed radioprotection of the HSC pool and 100% survival following lethal dose total body irradiation (TBI). BM HSCs from wild type mice expressed functional EGFR and systemic administration of EGF promoted the recovery of the HSC pool in vivo and the improved survival of mice following TBI. Conversely, administration of erlotinib, an EGFR antagonist, significantly decreased both HSC regeneration and mice survival following TBI. VavCre;EGFRfl/+ mice also demonstrated delayed recovery of BM stem/progenitor cells following TBI compared to VavCre;EGFR+/+ mice. Mechanistically, EGF reduced radiation-induced apoptosis of HSCs and mediated this effect via repression of the proapoptotic protein, PUMA. EGFR signaling regulates HSC regeneration following myelosuppressive injury. PMID:23377280

  5. Hepatocyte Growth Factor Regulates Angiotensin Converting Enzyme Expression*

    PubMed Central

    Day, Regina M.; Thiel, Gerald; Lum, Julie; Chévere, Rubén D.; Yang, Yongzhen; Stevens, Joanne; Sibert, Laura; Fanburg, Barry L.

    2008-01-01

    Hepatocyte growth factor (HGF) is a mitogen, morphogen, and motogen that functions in tissue healing and acts as an anti-fibrotic factor. The mechanism for this is not well understood. Recent studies implicate somatic angiotensin-converting enzyme (ACE) in fibrosis. We examined the effects of HGF on ACE expression in bovine pulmonary artery endothelial cells (BPAEC). Short term treatment of BPAEC with HGF transiently increased both ACE mRNA (3 h) and activity (24 h), as determined by ACE protease assays and reverse transcription-PCR. Incubation of BPAEC with HGF for longer periods suppressed ACE mRNA (6 h) and activity (72 h). In contrast, phorbol ester (PMA) treatment produced sustained increase in ACE mRNA and activity. We examined the short term molecular effects of HGF on ACE using PMA for comparison. HGF and PMA increased transcription from a luciferase reporter with the core ACE promoter, which contains a composite binding site for SP1/3 and Egr-1. Immunocytochemistry and electrophoretic mobility shift assay showed that both HGF and PMA increased Egr-1 binding. HGF also increased SP3 binding, as measured by EMSA. However, HGF and PMA increased the cellular activity of only Egr-1, not SP3, as measured by luciferase reporter assays. Deletion of the Egr-1 site in the reporter construct completely abrogated HGF-induced transcription but only ~50% of PMA-induced activity. Expression of dominant negative Egr-1 and SP3 blocked up-regulation of the ACE promoter by HGF but only reduced up-regulation by PMA. These results show that HGF transiently increases gene transcription of ACE via activation of Egr-1, whereas PMA regulation involves Egr-1 and additional factor(s). PMID:14679188

  6. A critical role of cardiac fibroblast-derived exosomes in activating renin angiotensin system in cardiomyocytes.

    PubMed

    Lyu, Linmao; Wang, Hui; Li, Bin; Qin, Qingyun; Qi, Lei; Nagarkatti, Mitzi; Nagarkatti, Prakash; Janicki, Joseph S; Wang, Xing Li; Cui, Taixing

    2015-12-01

    Chronic activation of the myocardial renin angiotensin system (RAS) elevates the local level of angiotensin II (Ang II) thereby inducing pathological cardiac hypertrophy, which contributes to heart failure. However, the precise underlying mechanisms have not been fully delineated. Herein we report a novel paracrine mechanism between cardiac fibroblasts (CF)s and cardiomyocytes whereby Ang II induces pathological cardiac hypertrophy. In cultured CFs, Ang II treatment enhanced exosome release via the activation of Ang II receptor types 1 (AT1R) and 2 (AT2R), whereas lipopolysaccharide, insulin, endothelin (ET)-1, transforming growth factor beta (TGFβ)1 or hydrogen peroxide did not. The CF-derived exosomes upregulated the expression of renin, angiotensinogen, AT1R, and AT2R, downregulated angiotensin-converting enzyme 2, and enhanced Ang II production in cultured cardiomyocytes. In addition, the CF exosome-induced cardiomyocyte hypertrophy was blocked by both AT1R and AT2R antagonists. Exosome inhibitors, GW4869 and dimethyl amiloride (DMA), inhibited CF-induced cardiomyocyte hypertrophy with little effect on Ang II-induced cardiomyocyte hypertrophy. Mechanistically, CF exosomes upregulated RAS in cardiomyocytes via the activation of mitogen-activated protein kinases (MAPKs) and Akt. Finally, Ang II-induced exosome release from cardiac fibroblasts and pathological cardiac hypertrophy were dramatically inhibited by GW4869 and DMA in mice. These findings demonstrate that Ang II stimulates CFs to release exosomes, which in turn increase Ang II production and its receptor expression in cardiomyocytes, thereby intensifying Ang II-induced pathological cardiac hypertrophy. Accordingly, specific targeting of Ang II-induced exosome release from CFs may serve as a novel therapeutic approach to treat cardiac pathological hypertrophy and heart failure.

  7. Vanadate induces necrotic death in neonatal rat cardiomyocytes through mitochondrial membrane depolarization.

    PubMed

    Soares, Sandra Sofia; Henao, Fernando; Aureliano, Manuel; Gutiérrez-Merino, Carlos

    2008-03-01

    Besides the well-known inotropic effects of vanadium in cardiac muscle, previous studies have shown that vanadate can stimulate cell growth or induce cell death. In this work, we studied the toxicity to neonatal rat ventricular myocytes (cardiomyocytes) of two vanadate solutions containing different oligovanadates distribution, decavanadate (containing decameric vanadate, V 10) and metavanadate (containing monomeric vanadate and also di-, tetra-, and pentavanadate). Incubation for 24 h with decavanadate or metavanadate induced necrotic cell death of cardiomyocytes, without significant caspase-3 activation. Only 10 microM total vanadium of either decavanadate (1 microM V 10) or metavanadate (10 microM total vanadium) was needed to produce 50% loss of cell viability after 24 h (assessed with MTT and propidium iodide assays). Atomic absorption spectroscopy showed that vanadium accumulation in cardiomyocytes after 24 h was the same when incubation was done with decavanadate or metavanadate. A decrease of 75% of the rate of mitochondrial superoxide anion generation, monitored with dihydroethidium, and a sustained rise of cytosolic calcium (monitored with Fura-2-loaded cardiomyocytes) was observed after 24 h of incubation of cardiomyocytes with decavanadate or metavanadate concentrations close to those inducing 50% loss of cell viability produced. In addition, mitochondrial membrane depolarization within cardiomyocytes, monitored with tetramethylrhodamine ethyl esther or with 3,3',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide, were observed after only 6 h of incubation with decavanadate or metavanadate. The concentration needed for 50% mitochondrial depolarization was 6.5 +/- 1 microM total vanadium for both decavanadate (0.65 microM V 10) and metavanadate. In conclusion, mitochondrial membrane depolarization was an early event in decavanadate- and monovanadate-induced necrotic cell death of cardiomyocytes.

  8. Regulation of growth hormone secretion by the growth hormone releasing hexapeptide (GHRP-6).

    PubMed

    Micic, D; Mallo, F; Peino, R; Cordido, F; Leal-Cerro, A; Garcia-Mayor, R V; Casanueva, F F

    1993-01-01

    Growth hormone (GH) secretion is regulated by a complex system of central and peripheral signals. Recently, a new GH-releasing hexapeptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) called GHRP-6 which specifically releases GH has been studied. In the present work the mechanism of action of GHRP-6 has been addressed in experimental animal models as well as in obese subjects. GHRP-6 releases GH independently of the hypothalamic factors GHRH and somatostatin and is a powerful GH releaser in obesity.

  9. The growth factor myostatin, a key regulator in skeletal muscle growth and homeostasis.

    PubMed

    Matsakas, A; Diel, P

    2005-03-01

    Skeletal muscle possesses the ability to both respond and adapt to changing environmental stimuli, leading to a set of metabolic and morphological adaptations, which allow it to better meet the energy demands of sustained physical activity. Great progress has been achieved over the past years by means of innovative molecular techniques, which has led to the discovery of new growth factors and the identification of molecular mechanisms involved in the regulation of muscle development. These findings provide new starting points to understand the molecular mechanisms involved in the adaptation of skeletal muscle to exercise training. One of these new identified growth factors is myostatin, a member of the transforming growth factor-beta family of proteins that has been demonstrated to play a fundamental role in the regulation of skeletal muscle growth during embryogenesis. Blocking of the myostatin signalling transduction pathway by specific inhibitors and genetic manipulations has been shown to result in a dramatic increase of skeletal muscle mass. This review focuses on the importance of myostatin in mediating skeletal muscle homeostasis in response to training as well as during the progress of myogenic disease, like atrophy or dystrophy. Manipulations of myostatin signalling may be useful for agriculture applications, treatment of muscle diseases, inhibition of muscle atrophy and last but not least as life style drugs in antiaging therapies or manipulations of the muscle to fat ratio. Drugs with the ability to modulate myostatin signalling may have the potential to enhance physical performance in athletes and therefore they probably represent a new class of doping substances.

  10. Humid heat exposure induced oxidative stress and apoptosis in cardiomyocytes through the angiotensin II signaling pathway.

    PubMed

    Wang, Xiaowu; Yuan, Binbin; Dong, Wenpeng; Yang, Bo; Yang, Yongchao; Lin, Xi; Gong, Gu

    2015-05-01

    Exposure to humid heat stress leads to the initiation of serious physiological dysfunction that may result in heat-related diseases, including heat stroke, heat cramp, heat exhaustion, and even death. Increasing evidences have shown that the humid heat stress-induced dysfunction of the cardiovascular system was accompanied with severe cardiomyocyte injury; however, the precise mechanism of heat stress-induced injury of cardiomyocyte remains unknown. In the present study, we hypothesized that humid heat stress promoted oxidative stress through the activation of angiotensin II (Ang II) in cardiomyocytes. To test our hypothesis, we established mouse models of humid heat stress. Using the animal models, we found that Ang II levels in serum were significantly up-regulated and that the Ang II receptor AT1 was increased in cardiomyocytes. The antioxidant ability in plasma and heart tissues which was detected by the ferric reducing/antioxidant power assay was also decreased with the increased ROS production under humid heat stress, as was the expression of antioxidant genes (SOD2, HO-1, GPx). Furthermore, we demonstrated that the Ang II receptor antagonist, valsartan, effectively relieved oxidative stress, blocked Ang II signaling pathway and suppressed cardiomyocyte apoptosis induced by humid heat stress. In addition, overexpression of antioxidant genes reversed cardiomyocyte apoptosis induced by Ang II. Overall, these results implied that humid heat stress increased oxidative stress and caused apoptosis of cardiomyocytes through the Ang II signaling pathway. Thus, targeting the Ang II signaling pathway may provide a promising approach for the prevention and treatment of cardiovascular diseases caused by humid heat stress.

  11. Regulation of epidermal growth factor receptor down-regulation by UBPY-mediated deubiquitination at endosomes.

    PubMed

    Mizuno, Emi; Iura, Takanobu; Mukai, Akiko; Yoshimori, Tamotsu; Kitamura, Naomi; Komada, Masayuki

    2005-11-01

    Ligand-activated receptor tyrosine kinases undergo endocytosis and are transported via endosomes to lysosomes for degradation. This "receptor down-regulation" process is crucial to terminate the cell proliferation signals produced by activated receptors. During the process, ubiquitination of the receptors serves as a sorting signal for their trafficking from endosomes to lysosomes. Here, we describe the role of a deubiquitinating enzyme UBPY/USP8 in the down-regulation of epidermal growth factor (EGF) receptor (EGFR). Overexpression of UBPY reduced the ubiquitination level of EGFR and delayed its degradation in EGF-stimulated cells. Immunopurified UBPY deubiquitinated EGFR in vitro. In EGF-stimulated cells, UBPY underwent ubiquitination and bound to EGFR. Overexpression of Hrs or a dominant-negative mutant of SKD1, proteins that play roles in the endosomal sorting of ubiquitinated receptors, caused the accumulation of endogenous UBPY on exaggerated endosomes. A catalytically inactive UBPY mutant clearly localized on endosomes, where it overlapped with EGFR when cells were stimulated with EGF. Finally, depletion of endogenous UBPY by RNA interference resulted in elevated ubiquitination and accelerated degradation of EGF-activated EGFR. We conclude that UBPY negatively regulates the rate of EGFR down-regulation by deubiquitinating EGFR on endosomes.

  12. Meis1 promotes poly (rC)-binding protein 2 expression and inhibits angiotensin II-induced cardiomyocyte hypertrophy.

    PubMed

    Zhang, Yunjiao; Si, Yi; Ma, Nan

    2016-01-01

    The poly(rC)-binding protein 2 (PCBP2) is currently reported to inhibit cardiac hypertrophy. However, how PCBP2 is regulated at transcriptional level remains unknown. Here, we show that Meis1, a PBX1-related homeobox gene, binds to PCBP2 promoter and promotes its transcription. In human failing heart tissues and murine hypertrophic heart tissues, the mRNA and protein levels of Meis1 are markedly downregulated, and the level of Meis1 significantly correlates with levels of Nppa, Myh7, and PCBP2. In neonatal rat cardiomyocytes, angiotensin II (Ang II) treatment induces hypertrophic growth of the cells (increase in cell size, enhanced protein synthesis, and hyperexpression of hypertrophic fetal genes), which are significantly inhibited by Meis1 overexpression or promoted by Meis1 knockdown. Meis1 also reduces Ang II-induced activation of Akt-mTOR pathway. Finally, we show that PCBP2 overexpression rescues the Meis1 effects of Akt-mTOR pathway and hypertrophy of cardiomyocytes. © 2015 IUBMB Life, 68(1):13-22, 2016.

  13. Urotensin II induction of neonatal cardiomyocyte hypertrophy involves the CaMKII/PLN/SERCA 2a signaling pathway.

    PubMed

    Shi, Hongtao; Han, Qinghua; Xu, Jianrong; Liu, Wenyuan; Chu, Tingting; Zhao, Li

    2016-05-25

    Although studies have shown that Urotensin II (UII) can induce cardiomyocyte hypertrophy and UII-induced cardiomyocyte hypertrophy model has been widely used for hypertrophy research, but its precise mechanism remains unknown. Recent researches have demonstrated that UII-induced cardiomyocyte hypertrophy has a relationship with the changes of intracellular Ca(2+) concentration. Therefore, the aim of this study was to investigate the mechanisms of cardiomyocyte hypertrophy induced by UII and to explore whether the calcium/calmodulin-dependent protein kinase II (CaMKII)-mediated up-regulating of phospholamban (PLN) Thr17-phosphorylation signaling pathway contributed to UII-induced cardiomyocyte hypertrophy. Primary cultures of neonatal rat cardiomyocytes were stimulated for 48h with UII. Cell size, protein/DNA contents and intracellular Ca(2+) were determined. Phosphorylated and total forms of CaMKII, PLN and the total amount of serco/endo-plasmic reticulum ATPases (SERCA 2a) were quantified by western blot. The responses of cardiomyocytes to UII were also evaluated after pretreatment with the CaMKII inhibitor, KN-93. These results showed that UII increased cell size, protein/DNA ratio and intracellular Ca(2+), consistent with a hypertrophic response. Furthermore, the phosphorylation of CaMKII and its downstream target PLN (Thr17), SERCA 2a levels were up-regulated by UII treatment. Conversely, treatment with KN-93 reversed all those effects of UII. Taken together, the results suggest that UII can induce cardiomyocyte hypertrophy through CaMKII-mediated up-regulating of PLN Thr17-phosphorylation signaling pathway.

  14. Cardiac fibroblast–derived microRNA passenger strand-enriched exosomes mediate cardiomyocyte hypertrophy

    PubMed Central

    Bang, Claudia; Batkai, Sandor; Dangwal, Seema; Gupta, Shashi Kumar; Foinquinos, Ariana; Holzmann, Angelika; Just, Annette; Remke, Janet; Zimmer, Karina; Zeug, Andre; Ponimaskin, Evgeni; Schmiedl, Andreas; Yin, Xiaoke; Mayr, Manuel; Halder, Rashi; Fischer, Andre; Engelhardt, Stefan; Wei, Yuanyuan; Schober, Andreas; Fiedler, Jan; Thum, Thomas

    2014-01-01

    In response to stress, the heart undergoes extensive cardiac remodeling that results in cardiac fibrosis and pathological growth of cardiomyocytes (hypertrophy), which contribute to heart failure. Alterations in microRNA (miRNA) levels are associated with dysfunctional gene expression profiles associated with many cardiovascular disease conditions; however, miRNAs have emerged recently as paracrine signaling mediators. Thus, we investigated a potential paracrine miRNA crosstalk between cardiac fibroblasts and cardiomyocytes and found that cardiac fibroblasts secrete miRNA-enriched exosomes. Surprisingly, evaluation of the miRNA content of cardiac fibroblast–derived exosomes revealed a relatively high abundance of many miRNA passenger strands (“star” miRNAs), which normally undergo intracellular degradation. Using confocal imaging and coculture assays, we identified fibroblast exosomal–derived miR-21_3p (miR-21*) as a potent paracrine-acting RNA molecule that induces cardiomyocyte hypertrophy. Proteome profiling identified sorbin and SH3 domain-containing protein 2 (SORBS2) and PDZ and LIM domain 5 (PDLIM5) as miR-21* targets, and silencing SORBS2 or PDLIM5 in cardiomyocytes induced hypertrophy. Pharmacological inhibition of miR-21* in a mouse model of Ang II–induced cardiac hypertrophy attenuated pathology. These findings demonstrate that cardiac fibroblasts secrete star miRNA–enriched exosomes and identify fibroblast-derived miR-21* as a paracrine signaling mediator of cardiomyocyte hypertrophy that has potential as a therapeutic target. PMID:24743145

  15. VEGF-C and aortic cardiomyocytes guide coronary artery stem development

    PubMed Central

    Chen, Heidi I.; Poduri, Aruna; Numi, Harri; Kivela, Riikka; Saharinen, Pipsa; McKay, Andrew S.; Raftrey, Brian; Churko, Jared; Tian, Xueying; Zhou, Bin; Wu, Joseph C.; Alitalo, Kari; Red-Horse, Kristy

    2014-01-01

    Coronary arteries (CAs) stem from the aorta at 2 highly stereotyped locations, deviations from which can cause myocardial ischemia and death. CA stems form during embryogenesis when peritruncal blood vessels encircle the cardiac outflow tract and invade the aorta, but the underlying patterning mechanisms are poorly understood. Here, using murine models, we demonstrated that VEGF-C–deficient hearts have severely hypoplastic peritruncal vessels, resulting in delayed and abnormally positioned CA stems. We observed that VEGF-C is widely expressed in the outflow tract, while cardiomyocytes develop specifically within the aorta at stem sites where they surround maturing CAs in both mouse and human hearts. Mice heterozygous for islet 1 (Isl1) exhibited decreased aortic cardiomyocytes and abnormally low CA stems. In hearts with outflow tract rotation defects, misplaced stems were associated with shifted aortic cardiomyocytes, and myocardium induced ectopic connections with the pulmonary artery in culture. These data support a model in which CA stem development first requires VEGF-C to stimulate vessel growth around the outflow tract. Then, aortic cardiomyocytes facilitate interactions between peritruncal vessels and the aorta. Derangement of either step can lead to mispatterned CA stems. Studying this niche for cardiomyocyte development, and its relationship with CAs, has the potential to identify methods for stimulating vascular regrowth as a treatment for cardiovascular disease. PMID:25271623

  16. Cardiomyocyte FGF signaling is required for Cx43 phosphorylation and cardiac gap junction maintenance.

    PubMed

    Sakurai, Takashi; Tsuchida, Mariko; Lampe, Paul D; Murakami, Masahiro

    2013-08-15

    Cardiac remodeling resulting from impairment of myocardial integrity leads to heart failure, through still incompletely understood mechanisms. The fibroblast growth factor (FGF) system has been implicated in tissue maintenance, but its role in the adult heart is not well defined. We hypothesized that the FGF system plays a role in the maintenance of cardiac homeostasis, and the impairment of cardiomyocyte FGF signaling leads to pathological cardiac remodeling. We showed that FGF signaling is required for connexin 43 (Cx43) localization at cell-cell contacts in isolated cardiomyocytes and COS7 cells. Lack of FGF signaling led to decreased Cx43 phosphorylation at serines 325/328/330 (S325/328/330), sites known to be important for assembly of gap junctions. Cx43 instability induced by FGF inhibition was restored by the Cx43 S325/328/330 phospho-mimetic mutant, suggesting FGF-dependent phosphorylation of these sites. Consistent with these in vitro findings, cardiomyocyte-specific inhibition of FGF signaling in adult mice demonstrated mislocalization of Cx43 at intercalated discs, whereas localization of N-cadherin and desmoplakin was not affected. This led to premature death resulting from impaired cardiac remodeling. We conclude that cardiomyocyte FGF signaling is essential for cardiomyocyte homeostasis through phosphorylation of Cx43 at S325/328/330 residues which are important for the maintenance of gap junction.

  17. Ligand Receptor-Mediated Regulation of Growth in Plants.

    PubMed

    Haruta, Miyoshi; Sussman, Michael R

    2017-01-01

    Growth and development of multicellular organisms are coordinately regulated by various signaling pathways involving the communication of inter- and intracellular components. To form the appropriate body patterns, cellular growth and development are modulated by either stimulating or inhibiting these pathways. Hormones and second messengers help to mediate the initiation and/or interaction of the various signaling pathways in all complex multicellular eukaryotes. In plants, hormones include small organic molecules, as well as larger peptides and small proteins, which, as in animals, act as ligands and interact with receptor proteins to trigger rapid biochemical changes and induce the intracellular transcriptional and long-term physiological responses. During the past two decades, the availability of genetic and genomic resources in the model plant species, Arabidopsis thaliana, has greatly helped in the discovery of plant hormone receptors and the components of signal transduction pathways and mechanisms used by these immobile but highly complex organisms. Recently, it has been shown that two of the most important plant hormones, auxin and abscisic acid (ABA), act through signaling pathways that have not yet been recognized in animals. For example, auxins stimulate cell elongation by bringing negatively acting transcriptional repressor proteins to the proteasome to be degraded, thus unleashing the gene expression program required for increasing cell size. The "dormancy" inducing hormone, ABA, binds to soluble receptor proteins and inhibits a specific class of protein phosphatases (PP2C), which activates phosphorylation signaling leading to transcriptional changes needed for the desiccation of the seeds prior to entering dormancy. While these two hormone receptors have no known animal counterparts, there are also many similarities between animal and plant signaling pathways. For example, in plants, the largest single gene family in the genome is the protein kinase

  18. Wnt5a Regulates Midbrain Dopaminergic Axon Growth and Guidance

    PubMed Central

    Blakely, Brette D.; Bye, Christopher R.; Fernando, Chathurini V.; Horne, Malcolm K.; Macheda, Maria L.; Stacker, Steven A.; Arenas, Ernest; Parish, Clare L.

    2011-01-01

    During development, precise temporal and spatial gradients are responsible for guiding axons to their appropriate targets. Within the developing ventral midbrain (VM) the cues that guide dopaminergic (DA) axons to their forebrain targets remain to be fully elucidated. Wnts are morphogens that have been identified as axon guidance molecules. Several Wnts are expressed in the VM where they regulate the birth of DA neurons. Here, we describe that a precise temporo-spatial expression of Wnt5a accompanies the development of nigrostriatal projections by VM DA neurons. In mice at E11.5, Wnt5a is expressed in the VM where it was found to promote DA neurite and axonal growth in VM primary cultures. By E14.5, when DA axons are approaching their striatal target, Wnt5a causes DA neurite retraction in primary cultures. Co-culture of VM explants with Wnt5a-overexpressing cell aggregates revealed that Wnt5a is capable of repelling DA neurites. Antagonism experiments revealed that the effects of Wnt5a are mediated by the Frizzled receptors and by the small GTPase, Rac1 (a component of the non-canonical Wnt planar cell polarity pathway). Moreover, the effects were specific as they could be blocked by Wnt5a antibody, sFRPs and RYK-Fc. The importance of Wnt5a in DA axon morphogenesis was further verified in Wnt5a−/− mice, where fasciculation of the medial forebrain bundle (MFB) as well as the density of DA neurites in the MFB and striatal terminals were disrupted. Thus, our results identify a novel role of Wnt5a in DA axon growth and guidance. PMID:21483795

  19. Black hole evolution - I. Supernova-regulated black hole growth

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Volonteri, Marta; Silk, Joseph; Devriendt, Julien; Slyz, Adrianne; Teyssier, Romain

    2015-09-01

    The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, and also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 1012 M⊙ halo at z = 2, which is the progenitor of a group of galaxies at z = 0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z > 3.5, efficient feedback from SNe forbids the formation of a settled disc as well as the accumulation of dense cold gas in the vicinity of the BH and starves the central compact object. As the galaxy and its halo accumulate mass, they become able to confine the nuclear inflows provided by major mergers and the BH grows at a sustained near-to-Eddington accretion rate. We argue that this mechanism should be ubiquitous amongst low-mass galaxies, corresponding to galaxies with a stellar mass below ≲ 109 M⊙ in our simulations.

  20. Age-Dependent Oxidative DNA Damage Does Not Correlate with Reduced Proliferation of Cardiomyocytes in Humans

    PubMed Central

    Li, Minghui; Liu, Jinfen; Jiang, Chuan; Zhang, Haibo; Ye, Lincai; Zheng, Jinghao

    2017-01-01

    Background Postnatal human cardiomyocyte proliferation declines rapidly with age, which has been suggested to be correlated with increases in oxidative DNA damage in mice and plays an important role in regulating cardiomyocyte proliferation. However, the relationship between oxidative DNA damage and age in humans is unclear. Methods Sixty right ventricular outflow myocardial tissue specimens were obtained from ventricular septal defect infant patients during routine congenital cardiac surgery. These specimens were divided into three groups based on age: group A (age 0–6 months), group B (age, 7–12 months), and group C (>12 months). Each tissue specimen was subjected to DNA extraction, RNA extraction, and immunofluorescence. Results Immunofluorescence and qRT-PCR analysis revealed that DNA damage markers—mitochondrial DNA copy number, oxoguanine 8, and phosphorylated ataxia telangiectasia mutated—were highest in Group B. However immunofluorescence and qRT-PCR demonstrated that two cell proliferation markers, Ki67 and cyclin D2, were decreased with age. In addition, wheat germ agglutinin-staining indicated that the average size of cardiomyocytes increased with age. Conclusions Oxidative DNA damage of cardiomyocytes was not correlated positively with age in human beings. Oxidative DNA damage is unable to fully explain the reduced proliferation of human cardiomyocytes. PMID:28099512

  1. Redox mechanisms of cardiomyocyte mitochondrial protection

    PubMed Central

    Bartz, Raquel R.; Suliman, Hagir B.; Piantadosi, Claude A.

    2015-01-01

    Oxidative and nitrosative stress are primary contributors to the loss of myocardial tissue in insults ranging from ischemia/reperfusion injury from coronary artery disease and heart transplantation to sepsis-induced myocardial dysfunction and drug-induced myocardial damage. This cell damage caused by oxidative and nitrosative stress leads to mitochondrial protein, DNA, and lipid modifications, which inhibits energy production and contractile function, potentially leading to cell necrosis and/or apoptosis. However, cardiomyocytes have evolved an elegant set of redox-sensitive mechanisms that respond to and contain oxidative and nitrosative damage. These responses include the rapid induction of antioxidant enzymes, mitochondrial DNA repair mechanisms, selective mitochondrial autophagy (mitophagy), and mitochondrial biogenesis. Coordinated cytoplasmic to nuclear cell-signaling and mitochondrial transcriptional responses to the presence of elevated cytoplasmic oxidant production, e.g., H2O2, allows nuclear translocation of the Nfe2l2 transcription factor and up-regulation of downstream cytoprotective genes such as heme oxygenase-1 which generates physiologic signals, such as CO that up-regulates Nfe212 gene transcription. Simultaneously, a number of other DNA binding transcription factors are expressed and/or activated under redox control, such as Nuclear Respiratory Factor-1 (NRF-1), and lead to the induction of genes involved in both intracellular and mitochondria-specific repair mechanisms. The same insults, particularly those related to vascular stress and inflammation also produce elevated levels of nitric oxide, which also has mitochondrial protein thiol-protective functions and induces mitochondrial biogenesis through cyclic GMP-dependent and perhaps other pathways. This brief review provides an overview of these pathways and interconnected cardiac repair mechanisms. PMID:26578967

  2. Growth differentiation factor 5 is a key physiological regulator of dendrite growth during development.

    PubMed

    Osório, Catarina; Chacón, Pedro J; Kisiswa, Lilian; White, Matthew; Wyatt, Sean; Rodríguez-Tébar, Alfredo; Davies, Alun M

    2013-12-01

    Dendrite size and morphology are key determinants of the functional properties of neurons. Here, we show that growth differentiation factor 5 (GDF5), a member of the bone morphogenetic protein (BMP) subclass of the transforming growth factor β superfamily with a well-characterised role in limb morphogenesis, is a key regulator of the growth and elaboration of pyramidal cell dendrites in the developing hippocampus. Pyramidal cells co-express GDF5 and its preferred receptors, BMP receptor 1B and BMP receptor 2, during development. In culture, GDF5 substantially increased dendrite, but not axon, elongation from these neurons by a mechanism that depends on activation of SMADs 1/5/8 and upregulation of the transcription factor HES5. In vivo, the apical and basal dendritic arbours of pyramidal cells throughout the hippocampus were markedly stunted in both homozygous and heterozygous Gdf5 null mutants, indicating that dendrite size and complexity are exquisitely sensitive to the level of endogenous GDF5 synthesis.

  3. FGF1-mediated cardiomyocyte cell cycle reentry depends on the interaction of FGFR-1 and Fn14.

    PubMed

    Novoyatleva, Tatyana; Sajjad, Amna; Pogoryelov, Denys; Patra, Chinmoy; Schermuly, Ralph T; Engel, Felix B

    2014-06-01

    Fibroblast growth factors (FGFs) signal through FGF receptors (FGFRs) mediating a broad range of cellular functions during embryonic development, as well as disease and regeneration during adulthood. Thus, it is important to understand the underlying molecular mechanisms that modulate this system. Here, we show that FGFR-1 can interact with the TNF receptor superfamily member fibroblast growth factor-inducible molecule 14 (Fn14) resulting in cardiomyocyte cell cycle reentry. FGF1-induced cell cycle reentry in neonatal cardiomyocytes could be blocked by Fn14 inhibition, while TWEAK-induced cell cycle activation was inhibited by blocking FGFR-1 signaling. In addition, costimulation experiments revealed a synergistic effect of FGF1 and TWEAK in regard to cardiomyocyte cell cycle induction via PI3K/Akt signaling. Overexpression of Fn14 with either FGFR-1 long [FGFR-1(L)] or FGFR-1 short [FGFR-1(S)] isoforms resulted after FGF1/TWEAK stimulation in cell cycle reentry of >40% adult cardiomyocytes. Finally, coimmunoprecipitation and proximity ligation assays indicated that endogenous FGFR-1 and Fn14 interact with each other in cardiomyocytes. This interaction was strongly enhanced in the presence of their corresponding ligands, FGF1 and TWEAK. Taken together, our data suggest that FGFR-1/Fn14 interaction may represent a novel endogenous mechanism to modulate the action of these receptors and their ligands and to control cardiomyocyte cell cycle reentry.

  4. Mena associates with Rac1 and modulates connexin 43 remodeling in cardiomyocytes.

    PubMed

    Ram, Rashmi; Wescott, Andrew P; Varandas, Katherine; Dirksen, Robert T; Blaxall, Burns C

    2014-01-01

    Mena, a member of the Ena/VASP family of actin regulatory proteins, modulates microfilaments and interacts with cytoskeletal proteins associated with heart failure. Mena is localized at the intercalated disc (ICD) of adult cardiac myocytes, colocalizing with numerous cytoskeletal proteins. Mena's role in the maintainence of mechanical myocardial stability at the cardiomyocyte ICD remains unknown. We hypothesized that Mena may modulate signals from the sarcolemma to the actin cytoskeleton at the ICD to regulate the expression and localization of connexin 43 (Cx43). The small GTPase Rac1 plays a pivotal role in the regulation of actin cytoskeletal reorganization and mediating morphological and transcriptional changes in cardiomyocytes. We found that Mena is associated with active Rac1 in cardiomyocytes and that RNAi knockdown of Mena increased Rac1 activity significantly. Furthermore, Mena knockdown increased Cx43 expression and altered Cx43 localization and trafficking at the ICD, concomitant with faster intercellular communication, as assessed by dye transfer between cardiomyocyte pairs. In mice overexpressing constitutively active Rac1, left ventricular Mena expression was increased significantly, concomitant with lateral redistribution of Cx43. These results suggest that Mena is a critical regulator of the ICD and is required for normal localization of Cx43 in part via regulation of Rac1.

  5. Prostaglandin E₂ promotes post-infarction cardiomyocyte replenishment by endogenous stem cells.

    PubMed

    Hsueh, Ying-Chang; Wu, Jasmine M F; Yu, Chun-Keung; Wu, Kenneth K; Hsieh, Patrick C H

    2014-04-01

    Although self-renewal ability of adult mammalian heart has been reported, few pharmacological treatments are known to promote cardiomyocyte regeneration after injury. In this study, we demonstrate that the critical period of stem/progenitor cell-mediated cardiomyocyte replenishment is initiated within 7 days and saturates on day 10 post-infarction. Moreover, blocking the inflammatory reaction with COX-2 inhibitors may also reduce the capability of endogenous stem/progenitor cells to repopulate lost cells. Injection of the COX-2 product PGE2 enhances cardiomyocyte replenishment in young mice and recovers cell renewal through attenuating TGF-β1 signaling in aged mice. Further analyses suggest that cardiac stem cells are PGE2-responsive and that PGE2 may regulate stem cell activity directly through the EP2 receptor or indirectly by modulating its micro-environment in vivo. Our findings provide evidence that PGE2 holds great potential for cardiac regeneration.

  6. Dataset of integrin-linked kinase protein: Protein interactions in cardiomyocytes identified by mass spectrometry.

    PubMed

    Traister, Alexandra; Lu, Mingliang; Coles, John G; Maynes, Jason T

    2016-06-01

    Using hearts from mice overexpressing integrin linked kinase (ILK) behind the cardiac specific promoter αMHC, we have performed immunoprecipitation and mass spectrometry to identify novel ILK protein:protein interactions that regulate cardiomyocyte activity and calcium flux. Integrin linked kinase complexes were captured from mouse heart lysates using a commercial antibody, with subsequent liquid chromatography tandem mass spectral analysis. Interacting partners were identified using the MASCOT server, and important interactions verified using reverse immunoprecipitation and mass spectrometry. All ILK interacting proteins were identified in a non-biased manner, and are stored in the ProteomeXchange Consortium via the PRIDE partner repository (reference ID PRIDE: PXD001053). The functional role of identified ILK interactions in cardiomyocyte function and arrhythmia were subsequently confirmed in human iPSC-cardiomyocytes.

  7. Cholesterol Depletion Alters Cardiomyocyte Subcellular Signaling and Increases Contractility

    PubMed Central

    McIntosh, Victoria J.; Abou Samra, Abdul B.; Mohammad, Ramzi M.; Lasley, Robert D.

    2016-01-01

    Membrane cholesterol levels play an important factor in regulating cell function. Sarcolemmal cholesterol is concentrated in lipid rafts and caveolae, which are flask-shaped invaginations of the plasma membrane. The scaffolding protein caveolin permits the enrichment of cholesterol in caveolae, and caveolin interactions with numerous proteins regulate their function. The purpose of this study was to determine whether acute reductions in cardiomyocyte cholesterol levels alter subcellular protein kinase activation, intracellular Ca2+ and contractility. Methods: Ventricular myocytes, isolated from adult Sprague Dawley rats, were treated with the cholesterol reducing agent methyl-β-cyclodextrin (MβCD, 5 mM, 1 hr, room temperature). Total cellular cholesterol levels, caveolin-3 localization, subcellular, ERK and p38 mitogen activated protein kinase (MAPK) signaling, contractility, and [Ca2+]i were assessed. Results: Treatment with MβCD reduced cholesterol levels by ~45 and shifted caveolin-3 from cytoskeleton and triton-insoluble fractions to the triton-soluble fraction, and increased ERK isoform phosphorylation in cytoskeletal, cytosolic, triton-soluble and triton-insoluble membrane fractions without altering their subcellular distributions. In contrast the primary effect of MβCD was on p38 subcellular distribution of p38α with little effect on p38 phosphorylation. Cholesterol depletion increased cardiomyocyte twitch amplitude and the rates of shortening and relaxation in conjunction with increased diastolic and systolic [Ca2+]i. Conclusions: These results indicate that acute reductions in membrane cholesterol levels differentially modulate basal cardiomyocyte subcellular MAPK signaling, as well as increasing [Ca2+]i and contractility. PMID:27441649

  8. Dechlorination of chloroacetanilide herbicides by plant growth regulator sodium bisulfite.

    PubMed

    Bian, Haitao; Chen, Jingwen; Cai, Xiyun; Liu, Ping; Wang, Ying; Huang, Liping; Qiao, Xianliang; Hao, Ce

    2009-08-01

    Chloroacetanilide herbicides are frequently detected in groundwater and surface waters, and pose high risks to aquatic biota. In this study, sodium bisulfite (NaHSO(3)), a plant growth regulator used in China, was used to remove three chloroacetanilide herbicides including alachlor, acetochlor and S-metolachlor. These herbicides were rapidly dechlorinated by NaHSO(3) in neutral conditions. The dechlorination was accelerated with increasing pH, temperature and NaHSO(3) concentrations. Kinetic analysis and mass spectrum identification revealed that the reaction followed S(N)2 nucleophilic substitution, in which the chlorine was replaced by the reactive specie sulfite. Alachlor and its isomer acetochlor had similar reaction rates, whereas they were more readily transformed than S-metolachlor that had larger steric hindrance and weaker electrophilicity. The transformation products were chloroacetanilide ethane sulfonic acids (ESAs), which were also encountered as major metabolites of these herbicides in natural environment via common metabolic pathways and were less toxic to green algae compared to the parent herbicides. These results indicate that NaHSO(3) can accelerate transformation of chloroacetanilide herbicides to the less toxic transformation products by nucleophilic substitution and dechlorination in aquatic environment. NaHSO(3) can be potentially used for the removal of chloroacetanilide herbicides from wastewater effluent, spill sites and accidental discharge.

  9. Branching geometry induced by lung self-regulated growth

    NASA Astrophysics Data System (ADS)

    Clément, Raphaël; Douady, Stéphane; Mauroy, Benjamin

    2012-12-01

    Branching morphogenesis is a widely spread phenomenon in nature. In organogenesis, it results from the inhomogeneous growth of the epithelial sheet, leading to its repeated branching into surrounding mesoderm. Lung morphogenesis is an emblematic example of tree-like organogenesis common to most mammals. The core signalling network is well identified, notably the Fgf10/Shh couple, required to initiate and maintain branching. In a previous study, we showed that the restriction by SHH of Fgf10 expression domain to distal mesenchyme spontaneously induces differential epithelial proliferation leading to branching. A simple Laplacian model qualitatively reproduced FGF10 dynamics in the mesenchyme and the spontaneous self-avoiding branching morphogenesis. However, early lung geometry has several striking features that remain to be addressed. In this paper, we investigate, through simulations and data analysis, if the FGF10-diffusion scenario accounts for the following aspects of lung morphology: size dispersion, asymmetry of branching events, and distal epithelium-mesothelium equilibrium. We report that they emerge spontaneously in the model, and that most of the underlying mechanisms can be understood as dynamical interactions between gradients and shape. This suggests that specific regulation may not be required for the emergence of these striking geometrical features.

  10. Regulation and 3 dimensional culture of tertiary follicle growth.

    PubMed

    Cheon, Yong-Pil

    2012-09-01

    It has been revealed that multiple cohorts of tertiary follicles develop during some animal estrous cycle and the human menstrual cycle. To reach developmental competence, oocytes need the support of somatic cells. During embryogenesis, the primordial germ cells appear, travel to the gonadal rudiments, and form follicles. The female germ cells develop within the somatic cells of the ovary, granulosa cells, and theca cells. How the oocyte and follicle cells support each other has been seriously studied. The latest technologies in genes and proteins and genetic engineering have allowed us to collect a great deal of information about folliculogenesis. For example, a few web pages (http://www.ncbi.nlm.nih.gov; http://mrg.genetics.washington.edu) provide access to databases of genomes, sequences of transcriptomes, and various tools for analyzing and discovering genes important in ovarian development. Formation of the antrum (tertiary follicle) is the final phase of folliculogenesis and the transition from intraovarian to extraovian regulation. This final step coordinates with the hypothalamic-pituitary-ovarian axis. On the other hand, currently, follicle physiology is under intense investigation, as little is known about how to overcome women's ovarian problems or how to develop competent oocytes from in vitro follicle culture or transplantation. In this review, some of the known roles of hormones and some of the genes involved in tertiary follicle growth and the general characteristics of tertiary follicles are summarized. In addition, in vitro culture of tertiary follicles is also discussed as a study model and an assisted reproductive technology model.

  11. Circadian clock regulation of skeletal muscle growth and repair

    PubMed Central

    Chatterjee, Somik; Ma, Ke

    2016-01-01

    Accumulating evidence indicates that the circadian clock, a transcriptional/translational feedback circuit that generates ~24-hour oscillations in behavior and physiology, is a key temporal regulatory mechanism involved in many important aspects of muscle physiology. Given the clock as an evolutionarily-conserved time-keeping mechanism that synchronizes internal physiology to environmental cues, locomotor activities initiated by skeletal muscle enable entrainment to the light-dark cycles on earth, thus ensuring organismal survival and fitness. Despite the current understanding of the role of molecular clock in preventing age-related sarcopenia, investigations into the underlying molecular pathways that transmit clock signals to the maintenance of skeletal muscle growth and function are only emerging. In the current review, the importance of the muscle clock in maintaining muscle mass during development, repair and aging, together with its contribution to muscle metabolism, will be discussed. Based on our current understandings of how tissue-intrinsic muscle clock functions in the key aspects muscle physiology, interventions targeting the myogenic-modulatory activities of the clock circuit may offer new avenues for prevention and treatment of muscular diseases. Studies of mechanisms underlying circadian clock function and regulation in skeletal muscle warrant continued efforts. PMID:27540471

  12. Evaluation of the control of mosquitoes with insect growth regulators.

    PubMed

    Ho, C M; Wu, S H; Wu, C C

    1990-07-01

    In this study, the effectiveness of eight insect growth regulators (IGRs) (chlorfluazuron, diflubenzuron, EL-494, flufenoxuron, teflubenzuron, juglone, plumbagin and methoprene) against five mosquito vectors (Armigeres subalbatus, Aedes albopictus, Aedes aegypti, Culex tritaeniorhynchus, and Culex quinquefasciatus) was investigated in the laboratory. The EC50s of chlorfluazuron, diflubenzuron, EL-494, flufenoxuron, teflubenzuron, and methoprene against the five mosquitoes ranged from 0.0001 to 0.3 ppm and those of juglone and plumbagin from 3-25 ppm. The five mosquito species had similar tolerances to the test IGRs. At pH 5 to 9, the effectiveness of the first five chemicals was very stable. After ultraviolet irradiation or heat management (45 degrees C-60 degrees C), diflubenzuron and flufenoxuron were very stable. EL-494 was not stable when exposed to ultraviolet irradiation or heat. Under 0.1 ppm, teflubenzuron was not stable upon exposure to heat and chlorfluazuron and methoprene were not stable when exposed to ultraviolet irradiation. Piperonyl butoxide reduces the effectiveness of the five IGRs. Administration of diflubenzuron (1-5 ppm), flufenoxuron (0.025 ppm), and teflubenzuron (1-5 ppm) reduced Culex quinquefasciatus larvae in ditches by 40-90%. The administration of diflubenzuron (0.5 ppm) to containers reduced 97% of the Aedes albopictus larvae.

  13. Insect growth regulators and insect control: a critical appraisal.

    PubMed Central

    Siddall, J B

    1976-01-01

    Insect growth regulators (IGRs) of the juvenile hormone type alter physiological processes essential to insect development and appear to act specifically on insects. Three natural juvenile hormones have been found in insects but not in other organisms. Future use of antagonists or inhibitors of hormone synthesis may be technically possible as an advantageous extension of pest control by IGRs. A documented survey of the properties, metabolism, toxicology, and uses of the most commercially advanced chemical, methoprene, shows it to be environmentally acceptable and toxicologically innocuous. Derivation of its current use patterns is discussed and limitations on these are noted. Residue levels and their measurement in the ppb region have allowed exemption from the requirement of tolerances in the EPA registered use of methoprene for mosquito control. Tolerances for foods accompany its fully approved use for control of manure breeding flies through a cattle feed supplement. The human health effects of using this chemical appear to be purely beneficial, but further advances through new IGR chemicals appear unlikely without major changes in regulatory and legislative policy. PMID:976222

  14. Circadian clock regulation of skeletal muscle growth and repair.

    PubMed

    Chatterjee, Somik; Ma, Ke

    2016-01-01

    Accumulating evidence indicates that the circadian clock, a transcriptional/translational feedback circuit that generates ~24-hour oscillations in behavior and physiology, is a key temporal regulatory mechanism involved in many important aspects of muscle physiology. Given the clock as an evolutionarily-conserved time-keeping mechanism that synchronizes internal physiology to environmental cues, locomotor activities initiated by skeletal muscle enable entrainment to the light-dark cycles on earth, thus ensuring organismal survival and fitness. Despite the current understanding of the role of molecular clock in preventing age-related sarcopenia, investigations into the underlying molecular pathways that transmit clock signals to the maintenance of skeletal muscle growth and function are only emerging. In the current review, the importance of the muscle clock in maintaining muscle mass during development, repair and aging, together with its contribution to muscle metabolism, will be discussed. Based on our current understandings of how tissue-intrinsic muscle clock functions in the key aspects muscle physiology, interventions targeting the myogenic-modulatory activities of the clock circuit may offer new avenues for prevention and treatment of muscular diseases. Studies of mechanisms underlying circadian clock function and regulation in skeletal muscle warrant continued efforts.

  15. Nrf2 is critical in defense against high glucose-induced oxidative damage in cardiomyocytes.

    PubMed

    He, Xiaoqing; Kan, Hong; Cai, Lu; Ma, Qiang

    2009-01-01

    Exposure to high levels of glucose induces the production of reactive oxygen species (ROS) in cardiomyocytes that may contribute to the development of cardiomyopathy in diabetes. Nuclear factor erythroid 2-related factor 2 (Nrf2) controls the antioxidant response element (ARE)-dependent gene regulation in response to oxidative stress. The role of Nrf2 in defense against high glucose-induced oxidative damage in cardiomyocytes was investigated. Glucose at high concentrations induced ROS production in both primary neonatal and adult cardiomyocytes from the Nrf2 wild type (WT) mouse heart, whereas, in Nrf2 knockout (KO) cells, ROS was significantly higher under basal conditions and high glucose markedly further increased ROS production in concentration and time-dependent manners. Concomitantly, high glucose induced significantly higher levels of apoptosis at lower concentrations and in shorter time in Nrf2 KO cells than in WT cells. Primary adult cardiomyocytes from control and diabetic mice also showed dependence on Nrf2 function for isoproterenol-stimulated contraction. Additionally, cardiomyocytes from Nrf2 KO mice exhibited increased sensitivity to 3-nitropropionic acid, an inhibitor of mitochondrial respiratory complex II, for both ROS production and apoptosis compared with Nrf2 WT cells, further emphasizing the role of Nrf2 in ROS defense in the cells. Mechanistically, Nrf2 was shown to mediate the basal expression and induction of ARE-controlled cytoprotective genes, Nqo1 and Ho1, at both mRNA and protein levels in cardiomyocytes, as both the basal and inducible expressions of the genes were lost in Nrf2 KO cells or largely reduced by Nrf2 SiRNA. The findings, for the first time, established Nrf2 as a critical regulator of defense against ROS in normal and diabetic hearts.

  16. Increased expression of estrogen-related receptor β during adaptation of adult cardiomyocytes to sustained hypoxia

    PubMed Central

    Cunningham, Kathryn F; Beeson, Gyda C; Beeson, Craig C; McDermott, Paul J

    2016-01-01

    Estrogen-related Receptors (ERR) are members of the steroid hormone receptor superfamily of transcription factors that regulate expression of genes required for energy metabolism including mitochondrial biogenesis, fatty acid oxidation and oxidative phosphorylation. While ERRα and EPPγ isoforms are known to share a wide array of target genes in the adult myocardium, the function of ERRβ has not been characterized in cardiomyocytes. The purpose of this study was to determine the role of ERRβ in regulating energy metabolism in adult cardiomyocytes in primary culture. Adult feline cardiomyocytes were electrically stimulated to contract in either hypoxia (0.5% O2) or normoxia (21% O2). As compared to baseline values measured in normoxia, ERRβ mRNA levels increased significantly after 8 hours of hypoxia and remained elevated over 24 h. Conversely, ERRβ mRNA decreased to normoxic levels after 4 hours of reoxygenation. Hypoxia increased expression of the α and β isoforms of Peroxisome Proliferator-Activated Receptor γ Coactivator-1 (PGC-1) mRNA by 6-fold and 3-fold, respectively. Knockdown of ERRβ expression via adenoviral-mediated delivery of ERRβ shRNA blocked hypoxia-induced increases in PGC-1β mRNA, but not PGC-1α mRNA. Loss of ERRβ had no effect on mtDNA content as measured after 24 h of hypoxia. To determine whether loss of ERRβ affected mitochondrial function, oxygen consumption rates (OCR) were measured in contracting versus quiescent cardiomyocytes in normoxia. OCR was significantly lower in contracting cardiomyocytes expressing ERRβ shRNA than scrambled shRNA controls. Maximal OCR also was reduced by ERRβ knockdown. In conclusion: 1) hypoxia increases in ERRβ mRNA expression in contracting cardiomyocytes; 2) ERRβ is required for induction of the PGC-1β isoform in response to hypoxia; 3) ERRβ expression is required to sustain OCR in normoxic conditions. PMID:27335690

  17. Simultaneous Assessment of Cardiomyocyte DNA Synthesis and Ploidy: A Method to Assist Quantification of Cardiomyocyte Regeneration and Turnover

    PubMed Central

    Richardson, Gavin D.

    2016-01-01

    Although it is accepted that the heart has a limited potential to regenerate cardiomyocytes following injury and that low levels of cardiomyocyte turnover occur during normal ageing, quantification of these events remains challenging. This is in part due to the rarity of the process and the fact that multiple cellular sources contribute to myocardial maintenance. Furthermore, DNA duplication within cardiomyocytes often leads to a polyploid cardiomyocyte and only rarely leads to new cardiomyocytes by cellular division. In order to accurately quantify cardiomyocyte turnover discrimination between these processes is essential. The protocol described here employs long term nucleoside labeling in order to label all nuclei which have arisen as a result of DNA replication and cardiomyocyte nuclei identified by utilizing nuclei isolation and subsequent PCM1 immunolabeling. Together this allows the accurate and sensitive identification of the nucleoside labeling of the cardiomyocyte nuclei population. Furthermore, 4′,6-diamidino-2-phenylindole labeling and analysis of nuclei ploidy, enables the discrimination of neo-cardiomyocyte nuclei from nuclei which have incorporated nucleoside during polyploidization. Although this method cannot control for cardiomyocyte binucleation, it allows a rapid and robust quantification of neo-cardiomyocyte nuclei while accounting for polyploidization. This method has a number of downstream applications including assessing the potential therapeutics to enhance cardiomyocyte regeneration or investigating the effects of cardiac disease on cardiomyocyte turnover and ploidy. This technique is also compatible with additional downstream immunohistological techniques, allowing quantification of nucleoside incorporation in all cardiac cell types. PMID:27285379

  18. Role of cardiomyocyte circadian clock in myocardial metabolic adaptation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marked circadian rhythmicities in cardiovascular physiology and pathophysiology exist. The cardiomyocyte circadian clock has recently been linked to circadian rhythms in myocardial gene expression, metabolism, and contractile function. For instance, the cardiomyocyte circadian clock is essential f...

  19. miR-138 protects cardiomyocytes from hypoxia-induced apoptosis via MLK3/JNK/c-jun pathway

    SciTech Connect

    He, Siyi; Liu, Peng; Jian, Zhao; Li, Jingwei; Zhu, Yun; Feng, Zezhou; Xiao, Yingbin

    2013-11-29

    Highlights: •First time to find miR-138 is up-regulated in hypoxic cardiomyocytes. •First time to find miR-138 targets MLK3 and regulates JNK/c-jun pathway. •Rare myocardial biopsy of patients with CHD were collected. •Both silence and overexpression of miR-138 were implemented. •Various methods were used to detect cell function. -- Abstract: Cardiomyocytes experience a series of complex endogenous regulatory mechanisms against apoptosis induced by chronic hypoxia. MicroRNAs are a class of endogenous small non-coding RNAs that regulate cellular pathophysiological processes. Recently, microRNA-138 (miR-138) has been found related to hypoxia, and beneficial for cell proliferation. Therefore, we intend to study the role of miR-138 in hypoxic cardiomyocytes and the main mechanism. Myocardial samples of patients with congenital heart disease (CHD) were collected to test miR-138 expression. Agomir or antagomir of miR-138 was transfected into H9C2 cells to investigate its effect on cell apoptosis. Higher miR-138 expression was observed in patients with cyanotic CHD, and its expression gradually increased with prolonged hypoxia time in H9C2 cells. Using MTT and LDH assays, cell growth was significantly greater in the agomir group than in the negative control (NC) group, while antagomir decreased cell survival. Dual luciferase reporter gene and Western-blot results confirmed MLK3 was a direct target of miR-138. It was found that miR-138 attenuated hypoxia-induced apoptosis using TUNEL, Hoechst staining and Annexin V-PE/7-AAD flow cytometry analysis. We further detected expression of apoptosis-related proteins. In the agomir group, the level of pro-apoptotic proteins such as cleaved-caspase-3, cleaved-PARP and Bad significantly reduced, while Bcl-2 and Bcl-2/Bax ratio increased. Opposite changes were observed in the antagomir group. Downstream targets of MLK3, JNK and c-jun, were also suppressed by miR-138. Our study demonstrates that up-regulation of miR-138 plays

  20. Regulation of senescence in bean leaf discs by light and chemical growth regulators.

    PubMed

    Goldthwaite, J J; Laetsch, W M

    1967-12-01

    The senescence of excised discs of primary leaves of Phaseolus vulgaris, L., var. Red Kidney was followed by measuring the net breakdown of protein and chlorophyll. The chemical growth regulators indoleacetic acid, 2,4-dichlorophenoxy-acetic acid, gibberellic acid, kinetin, and 6-benzylaminopurine were relatively ineffective in retarding senescence in this tissue. White light, on the other hand, was very effective in senescence retardation. The response to light did not have the characteristics of a low energy (phytochrome) response and was blocked by concentrations of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea which inhibited photosynthesis in the leaf discs. The light-induced retardation of senescence was concluded to be dependent on photosynthesis.

  1. Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent.

    PubMed

    Kuo, Jong-Tar; Chang, Yu-Jen; Tseng, Ching-Ping

    2003-10-23

    In contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli.

  2. Rac regulates vascular endothelial growth factor stimulated motility.

    PubMed

    Soga, N; Connolly, J O; Chellaiah, M; Kawamura, J; Hruska, K A

    2001-01-01

    During angiogenesis endothelial cells migrate towards a chemotactic stimulus. Understanding the mechanism of endothelial cell migration is critical to the therapeutic manipulation of angiogenesis and ultimately cancer prevention. Vascular endothelial growth factor (VEGF) is a potent chemotactic stimulus of endothelial cells during angiogenesis. The endothelial cell signal transduction pathway of VEGF represents a potential target for cancer therapy, but the mechanisms of post-receptor signal transduction including the roles of rho family GTPases in regulating the cytoskeletal effects of VEGF in endothelial cells are not understood. Here we analyze the mechanisms of cell migration in the mouse brain endothelial cell line (bEND3). Stable transfectants containing a tetracycline repressible expression vector were used to induce expression of Rac mutants. Endothelial cell haptotaxis was stimulated by constitutively active V12Rac on collagen and vitronectin coated supports, and chemotaxis was further stimulated by VEGF. Osteopontin coated supports were the most stimulatory to bEND3 haptotaxis, but VEGF was not effective in further increasing migration on osteopontin coated supports. Haptotaxis on support coated with collagen, vitronectin, and to a lesser degree osteopontin was inhibited by N17 Rac. N17 Rac expression blocked stimulation of endothelial cell chemotaxis by VEGF. As part of the chemotactic stimulation, VEGF caused a loss of actin organization at areas of cell-cell contact and increased stress fiber expression in endothelial cells which were directed towards pores in the transwell membrane. N17 Rac prevented the stimulation of cell-cell contact disruption and the stress fiber stimulation by VEGF. These data demonstrate two pathways of regulating endothelial cell motility, one in which Rac is activated by matrix/integrin stimulation and is a crucial modulator of endothelial cell haptotaxis. The other pathway, in the presence of osteopontin, is Rac independent

  3. Rat Prolactinoma cell growth regulation by Epidermal Growth Factor receptor ligands

    PubMed Central

    Vlotides, George; Siegel, Emily; Donangelo, Ines; Gutman, Shiri; Ren, Song-Guang; Melmed, Shlomo

    2008-01-01

    Epidermal growth factor (EGF) regulates pituitary development, hormone synthesis and cell proliferation. Although ErbB receptor family members are expressed in pituitary tumors, effects of EGF signaling on pituitary tumors are not known. Immunoprecipitation and Western blot confirmed EGFR and p185c-neu protein expression in GH3 lacto-somatotroph but not in ACTH-secreting AtT20 pituitary tumor cells. EGF (5 nM) selectively enhanced baseline (~ 4-fold) and serum-induced (> 6-fold) PRL mRNA levels, while gefitinib, an EGFR antagonist, suppressed serum-induced cell proliferation and Pttg1 expression, blocked PRL gene expression, and reversed EGF-mediated somatotroph-lactotroph phenotype switching. Downstream EGFR signaling by ERK, but not PI3K or PKC, mediated the gefitinib-response. Tumors in athymic mice implanted sc with GH3 cells resulted in weight gain accompanied by increased serum PRL, GH and IGF-I levels. Gefitinib decreased tumor volumes and peripheral hormone levels by ~ 30% and restored normal mouse body weight patterns. Mice treated with gefitinib exhibited decreased tumor tissue ERK1/2 phosphorylation and downregulated tumor PRL and Pttg1 mRNA abundance. These results show that EGFR inhibition controls tumor growth and PRL secretion in experimental lacto-somatotroph tumors. EGFR inhibitors could therefore be useful for control of PRL secretion and tumor load in prolactinomas resistant to dopaminergic treatment, or for those prolactinomas undergoing rare malignant transformation. PMID:18676863

  4. Developmental regulation of human truncated nerve growth factor receptor

    SciTech Connect

    DiStefano, P.S.; Clagett-Dame, M.; Chelsea, D.M.; Loy, R. )

    1991-01-01

    Monoclonal antibodies (designated XIF1 and IIIG5) recognizing distinct epitopes of the human truncated nerve growth factor receptor (NGF-Rt) were used in a two-site radiometric immunosorbent assay to monitor levels of NGF-Rt in human urine as a function of age. Urine samples were collected from 70 neurologically normal subjects ranging in age from 1 month to 68 years. By using this sensitive two-site radiometric immunosorbent assay, NGF-Rt levels were found to be highest in urine from 1-month old subjects. By 2.5 months, NGF-Rt values were half of those seen at 1 month and decreased more gradually between 0.5 and 15 years. Between 15 and 68 years, urine NGF-Rt levels were relatively constant at 5% of 1-month values. No evidence for diurnal variation of adult NGF-Rt was apparent. Pregnant women in their third trimester showed significantly elevated urine NGF-Rt values compared with age-matched normals. Affinity labeling of NGF-Rt with 125I-NGF followed by immunoprecipitation with ME20.4-IgG and gel autoradiography indicated that neonatal urine contained high amounts of truncated receptor (Mr = 50 kd); decreasingly lower amounts of NGF-Rt were observed on gel autoradiograms with development, indicating that the two-site radiometric immunosorbent assay correlated well with the affinity labeling technique for measuring NGF-Rt. NGF-Rt in urines from 1-month-old and 36-year-old subjects showed no differences in affinities for NGF or for the monoclonal antibody IIIG5. These data show that NGF-Rt is developmentally regulated in human urine, and are discussed in relation to the development and maturation of the peripheral nervous system.

  5. In situ mechanical analysis of cardiomyocytes at nano scales

    NASA Astrophysics Data System (ADS)

    Liu, Yuansheng; Feng, Jiantao; Shi, Liang; Niu, Ruibin; Sun, Quanmei; Liu, Hao; Li, Jing; Guo, Jihong; Zhu, Jihong; Han, Dong

    2011-12-01

    Nanomechanical behaviors of single living cardiomyocytes are quantitatively observed using calculated torsions and deflections of an AFM cantilever. The lateral contractions are related to the calcium intensity within rather than the vertical beating power of the cardiomyocytes. Drug-induced nanomechanical changes of cardiomyocytes were further investigated by measuring lateral contractions in real time.

  6. Effects of growth regulator herbicide on downy brome (Bromus tectorum) seed production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research showed growth regulator herbicides, such as picloram and aminopyralid, have a sterilizing effect on Japanese brome (Bromus japonicus Thunb.) that can reduce this invasive annual grass’s seed production nearly 100%. This suggests growth regulators might be used to control invasive ...

  7. Investigating Preservice Teachers' Professional Growth in Self-Regulated Learning Environments

    ERIC Educational Resources Information Center

    Kramarski, Bracha; Michalsky, Tova

    2009-01-01

    Educational reforms have suggested that the ability to self-regulate learning is essential for teachers' professional growth during their entire career as well as for their ability to promote these processes among students. This study observed teachers' professional growth along 3 dimensions: self-regulated learning (SRL) in pedagogical context,…

  8. Insulin Stimulates Mitochondrial Fusion and Function in Cardiomyocytes via the Akt-mTOR-NFκB-Opa-1 Signaling Pathway

    PubMed Central

    Parra, Valentina; Verdejo, Hugo E.; Iglewski, Myriam; del Campo, Andrea; Troncoso, Rodrigo; Jones, Deborah; Zhu, Yi; Kuzmicic, Jovan; Pennanen, Christian; Lopez‑Crisosto, Camila; Jaña, Fabián; Ferreira, Jorge; Noguera, Eduard; Chiong, Mario; Bernlohr, David A.; Klip, Amira; Hill, Joseph A.; Rothermel, Beverly A.; Abel, Evan Dale; Zorzano, Antonio; Lavandero, Sergio

    2014-01-01

    Insulin regulates heart metabolism through the regulation of insulin-stimulated glucose uptake. Studies have indicated that insulin can also regulate mitochondrial function. Relevant to this idea, mitochondrial function is impaired in diabetic individuals. Furthermore, the expression of Opa-1 and mitofusins, proteins of the mitochondrial fusion machinery, is dramatically altered in obese and insulin-resistant patients. Given the role of insulin in the control of cardiac energetics, the goal of this study was to investigate whether insulin affects mitochondrial dynamics in cardiomyocytes. Confocal microscopy and the mitochondrial dye MitoTracker Green were used to obtain three-dimensional images of the mitochondrial network in cardiomyocytes and L6 skeletal muscle cells in culture. Three hours of insulin treatment increased Opa-1 protein levels, promoted mitochondrial fusion, increased mitochondrial membrane potential, and elevated both intracellular ATP levels and oxygen consumption in cardiomyocytes in vitro and in vivo. Consequently, the silencing of Opa-1 or Mfn2 prevented all the metabolic effects triggered by insulin. We also provide evidence indicating that insulin increases mitochondrial function in cardiomyocytes through the Akt-mTOR-NFκB signaling pathway. These data demonstrate for the first time in our knowledge that insulin acutely regulates mitochondrial metabolism in cardiomyocytes through a mechanism that depends on increased mitochondrial fusion, Opa-1, and the Akt-mTOR-NFκB pathway. PMID:24009260

  9. The A-kinase anchoring protein (AKAP)-Lbc-signaling complex mediates alpha1 adrenergic receptor-induced cardiomyocyte hypertrophy.

    PubMed

    Appert-Collin, Aline; Cotecchia, Susanna; Nenniger-Tosato, Monique; Pedrazzini, Thierry; Diviani, Dario

    2007-06-12

    In response to various pathological stresses, the heart undergoes a pathological remodeling process that is associated with cardiomyocyte hypertrophy. Because cardiac hypertrophy can progress to heart failure, a major cause of lethality worldwide, the intracellular signaling pathways that control cardiomyocyte growth have been the subject of intensive investigation. It has been known for more than a decade that the small molecular weight GTPase RhoA is involved in the signaling pathways leading to cardiomyocyte hypertrophy. Although some of the hypertrophic pathways activated by RhoA have now been identified, the identity of the exchange factors that modulate its activity in cardiomyocytes is currently unknown. In this study, we show that AKAP-Lbc, an A-kinase anchoring protein (AKAP) with an intrinsic Rho-specific guanine nucleotide exchange factor activity, is critical for activating RhoA and transducing hypertrophic signals downstream of alpha1-adrenergic receptors (ARs). In particular, our results indicate that suppression of AKAP-Lbc expression by infecting rat neonatal ventricular cardiomyocytes with lentiviruses encoding AKAP-Lbc-specific short hairpin RNAs strongly reduces both alpha1-AR-mediated RhoA activation and hypertrophic responses. Interestingly, alpha1-ARs promote AKAP-Lbc activation via a pathway that requires the alpha subunit of the heterotrimeric G protein G12. These findings identify AKAP-Lbc as the first Rho-guanine nucleotide exchange factor (GEF) involved in the signaling pathways leading to cardiomyocytes hypertrophy.

  10. Identifying panaxynol, a natural activator of nuclear factor erythroid-2 related factor 2 (Nrf2) from American ginseng as a suppressor of inflamed macrophage-induced cardiomyocyte hypertrophy

    PubMed Central

    Qu, Chen; Li, Bin; Lai, Yimu; Li, Hechu; Windust, Anthony; Hofseth, Lorne J.; Nagarkatti, Mitzi; Nagarkatti, Prakash; Wang, Xing Li; Tang, Dongqi; Janicki, Joseph S.; Tian, Xingsong; Cui, Taixing

    2015-01-01

    Ethnopharmacological relevance American ginseng is capable of ameliorating cardiac dysfunction and activating Nrf2, a master regulator of antioxidant defense, in the heart. This study was designed to isolate compounds from American ginseng and to determine those responsible for the Nrf2-mediated resolution of inflamed macrophage-induced cardiomyocyte hypertrophy. Materials and methods A standardized crude extract of American ginseng was supplied by the National Research Council of Canada, Institute for National Measurement Standards. A bioassay-based fractionization of American ginseng was performed to identify the putative substances which could activate Nrf2-mediated suppression of pro-inflammatory cytokine expression in macrophages and macrophage-mediated pro-hypertrophic growth in cardiomyocytes. Results A hexane fraction of an anti-inflammatory crude extract of American ginseng was found to be most effective in suppressing the inflammatory responses in macrophages. Preparative, reverse-phase HPLC and a comparative analysis by analytical scale LC–UV/MS revealed the hexane fraction contains predominantly C17 polyacetylenes and linolenic acid. Panaxynol, one of the major polyacetylenes, was found to be a potent Nrf2 activator. Panaxynol posttranscriptionally activated Nrf2 by inhibiting Kelch-like ECH-associated protein (Keap) 1-mediated degradation without affecting the binding of Keap1 and Nrf2. Moreover, panaxynol suppressed a selected set of cytokine expression via the activation of Nrf2 while minimally regulating nuclear factor-kappa B (NF-κB)-mediated cytokine expression in macrophages. It also dramatically inhibited the inflamed macrophage-mediated cardiomyocyte death and hypertrophy by activating Nrf2 in macrophages. Conclusions These results demonstrate that American ginseng-derived panaxynol is a specific Nrf2 activator and panaxynol-activated Nrf2 signaling is at least partly responsible for American ginseng-induced health benefit in the heart. PMID

  11. Inhibition of aldehyde dehydrogenase 2 activity enhances antimycin-induced rat cardiomyocytes apoptosis through activation of MAPK signaling pathway.

    PubMed

    Zhang, Peng; Xu, Danling; Wang, Shijun; Fu, Han; Wang, Keqiang; Zou, Yunzeng; Sun, Aijun; Ge, Junbo

    2011-12-01

    Aldehyde dehydrogenase 2 (ALDH2), a mitochondrial-specific enzyme, has been proved to be involved in oxidative stress-induced cell apoptosis, while little is known in cardiomyocytes. This study was aimed at investigating the role of ALDH2 in antimycin A-induced cardiomyocytes apoptosis by suppressing ALDH2 activity with a specific ALDH2 inhibitor Daidzin. Antimycin A (40μg/ml) was used to induce neonatal cardiomyocytes apoptosis. Daidzin (60μM) effectively inhibited ALDH2 activity by 50% without own effect on cell apoptosis, and significantly enhanced antimycin A-induced cardiomyocytes apoptosis from 33.5±4.4 to 56.5±6.4% (Hochest method, p<0.05), and from 57.9±1.9 to 74.0±11.9% (FACS, p<0.05). Phosphorylation of activated MAPK signaling pathway, including extracellular signal-regulated kinase (ERK1/2), c-Jun NH2-terminal kinase (JNK) and p38 was also increased in antimycin A and daidzin treated cardiomyocytes compared to the cells treated with antimycin A alone. These findings indicated that modifying mitochondrial ALDH2 activity/expression might be a potential therapeutic option on reducing oxidative insults induced cardiomyocytes apoptosis.

  12. Greater cardiomyocyte density on aligned compared with random carbon nanofibers in polymer composites

    PubMed Central

    Asiri, Abdullah M; Marwani, Hadi M; Khan, Sher Bahadar; Webster, Thomas J

    2014-01-01

    Carbon nanofibers (CNFs) randomly embedded in poly (lactic-co-glycolic-acid) (PLGA) composites have recently been shown to promote cardiomyocyte growth when compared with conventional PLGA without CNFs. It was shown then that PLGA:CNF composites were conductive and that conductivity increased as greater amounts of CNFs were added to pure PLGA. Moreover, tensile tests showed that addition of CNFs increased the tensile strength of the PLGA composite to mimic that of natural heart tissue. Most importantly, throughout all cytocompatibility experiments, cardiomyocytes were viable and expressed important biomarkers that were greatest on 50:50 wt% CNF:PLGA composites. The increased selective adsorption of fibronectin and vitronectin (critical proteins that mediate cardiomyocyte function) onto such composites proved to be the mechanism of action. However, the natural myocardium is anisotropic in terms of mechanical and electrical properties, which was not emulated in these prior PLGA:CNF composites. Thus, the aim of this in vitro study was to create and characterize CNFs aligned in PLGA composites (at 50:50 wt%, including their mechanical and electrical properties and cardiomyocyte density), comparing such results with randomly oriented CNFs in PLGA. Specifically, CNFs were added to soluble biodegradable PLGA (50:50 PGA:PLA weight ratio) and aligned by applying a voltage and then allowing the polymer to cure. CNF surface micron patterns (20 μm wide) on PLGA were then fabricated through a mold method to further mimic myocardium anisotropy. The results demonstrated anisotropic mechanical and electrical properties and significantly improved cardiomyocyte density for up to 5 days on CNFs aligned in PLGA compared with being randomly oriented in PLGA. These results indicate that CNFs aligned in PLGA should be further explored for improving cardiomyocyte density, which is necessary in numerous cardiovascular applications. PMID:25489241

  13. Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction.

    PubMed

    Ngkelo, Anta; Richart, Adèle; Kirk, Jonathan A; Bonnin, Philippe; Vilar, Jose; Lemitre, Mathilde; Marck, Pauline; Branchereau, Maxime; Le Gall, Sylvain; Renault, Nisa; Guerin, Coralie; Ranek, Mark J; Kervadec, Anaïs; Danelli, Luca; Gautier, Gregory; Blank, Ulrich; Launay, Pierre; Camerer, Eric; Bruneval, Patrick; Menasche, Philippe; Heymes, Christophe; Luche, Elodie; Casteilla, Louis; Cousin, Béatrice; Rodewald, Hans-Reimer; Kass, David A; Silvestre, Jean-Sébastien

    2016-06-27

    Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit-independent MC-deficient (Cpa3(Cre/+)) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca(2+) desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force-Ca(2+) interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators.

  14. Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction

    PubMed Central

    Richart, Adèle; Vilar, Jose; Lemitre, Mathilde; Marck, Pauline; Branchereau, Maxime; Guerin, Coralie; Gautier, Gregory; Blank, Ulrich; Heymes, Christophe; Luche, Elodie; Cousin, Béatrice; Rodewald, Hans-Reimer

    2016-01-01

    Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit–independent MC-deficient (Cpa3Cre/+) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca2+ desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force–Ca2+ interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators. PMID:27353089

  15. Developmental regulation of insulin-like growth factor-I and growth hormone receptor gene expression.

    PubMed

    Shoba, L; An, M R; Frank, S J; Lowe, W L

    1999-06-25

    During development, the insulin-like growth factor I (IGF-I) gene is expressed in a tissue specific manner; however, the molecular mechanisms governing its developmental regulation remain poorly defined. To examine the hypothesis that expression of the growth hormone (GH) receptor accounts, in part, for the tissue specific expression of the IGF-I gene during development, the developmental regulation of IGF-I and GH receptor gene expression in rat tissues was examined. The level of IGF-I and GH receptor mRNA was quantified in RNA prepared from rats between day 17 of gestation (E17) and 17 months of age (17M) using an RNase protection assay. Developmental regulation of IGF-I gene expression was tissue specific with four different patterns of expression seen. In liver, IGF-I mRNA levels increased markedly between E17 and postnatal day 45 (P45) and declined thereafter. In contrast, in brain, skeletal muscle and testis, IGF-I mRNA levels decreased between P5 and 4M but were relatively unchanged thereafter. In heart and kidney, a small increase in IGF-I mRNA levels was observed between the early postnatal period and 4 months, whereas in lung, minimal changes were observed during development. The changes in GH receptor mRNA levels were, in general, coordinate with the changes in IGF-I mRNA levels, except in skeletal muscle. Interestingly, quantification of GH receptor levels by Western blot analysis in skeletal muscle demonstrated changes coordinate with IGF-I mRNA levels. The levels of the proteins which mediate GH receptor signaling (STAT1, -3, and -5, and JAK2) were quantified by Western blot analysis. These proteins also are expressed in a tissue specific manner during development. In some cases, the pattern of expression was coordinate with IGF-I gene expression, whereas in others it was discordant. To further define molecular mechanisms for the developmental regulation of IGF-I gene expression, protein binding to IGFI-FP1, a protein binding site that is in the major

  16. Comparison of growth and metabolic regulation between wild, domesticated and transgenic salmonids.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To gain a better understanding of the aspects underlying normal and growth hormone enhanced growth in salmonids, quantitative expression analysis was performed for a number of genes related to muscle growth, metabolism, immunology and energy regulation. This analysis was performed in liver and musc...

  17. Hormonal regulation of wheat growth during hydroponic culture

    NASA Technical Reports Server (NTRS)

    Wetherell, Donald

    1988-01-01

    Hormonal control of root growth has been explored as one means to alleviate the crowding of plant root systems experienced in prototype hydroponic biomass production chambers being developed by the CELSS Breadboard Project. Four plant hormones, or their chemical analogs, which have been reported to selectively inhibit root growth, were tested by adding them to the nutrient solutions on day 10 of a 25 day growth test using spring wheat in hydroponic cultures. Growth and morphological changes is both shoot and root systems were evaluated. In no case was it possible to inhibit root growth without a comparable inhibition of shoot growth. It was concluded that this approach is unlikely to prove useful for wheat.

  18. Body size regulation and insulin-like growth factor signaling.

    PubMed

    Hyun, Seogang

    2013-07-01

    How animals achieve their specific body size is a fundamental, but still largely unresolved, biological question. Over the past decades, studies on the insect model system have provided some important insights into the process of body size determination and highlighted the importance of insulin/insulin-like growth factor signaling. Fat body, the Drosophila counterpart of liver and adipose tissue, senses nutrient availability and controls larval growth rate by modulating peripheral insulin signaling. Similarly, insulin-like growth factor I produced from liver and muscle promotes postnatal body growth in mammals. Organismal growth is tightly coupled with the process of sexual maturation wherein the sex steroid hormone attenuates body growth. This review summarizes some important findings from Drosophila and mammalian studies that shed light on the general mechanism of animal size determination.

  19. Boundary genes in regulation and evolution of secondary growth.

    PubMed

    Yordanov, Yordan S; Busov, Victor

    2011-05-01

    Many extant land plants display secondary growth originating in a lateral meristem known as vascular cambium. A conspicuous product of secondary growth is wood which dominates terrestrial ecosystem biomass. Despite the economic and ecological significance of the process the underlying molecular mechanism are still poorly understood. We have recently shown that members of the LBD transcription factor family play function in control of secondary growth. Here we propose a mechanistic model of LBD regulatory roles. We also show how these roles may be linked to evolutionary changes in level and pattern of wood formation that provide structural and functional innovations in wood anatomy in relation to species growth habit and biology. 

  20. [The peculiarities of calcium metabolism regulation in different periods of growth and development].

    PubMed

    Moĭsa, S S; Nozdrachev, A D

    2014-01-01

    The review contains literature data about calcium metabolism regulation in different periods of growth and development. The analyses of retrospective and current sources of information about the regulation of calcium homeostasis under the theory of functional systems, the regulation of calcium metabolism in prenatal and postnatal periods of the development, the significance of calcium metabolism disturbances in the development of pathological conditions were showed.

  1. The Anti-Apoptotic and Cardioprotective Effects of Salvianolic Acid A on Rat Cardiomyocytes following Ischemia/Reperfusion by DUSP-Mediated Regulation of the ERK1/2/JNK Pathway

    PubMed Central

    Chen, Qiuping; Zhu, Shasha; Liu, Yang; Pan, Defeng; Chen, Xiaohu; Li, Dongye

    2014-01-01

    The purpose of this study was to observe the effects of salvianolic acid A (SAA) pretreatment on the myocardium during ischemia/reperfusion (I/R) and to illuminate the interrelationships among dual specificity protein phosphatase (DUSP) 2/4/16, ERK1/2 and JNK pathways during myocardial I/R, with the ultimate goal of elucidating how SAA exerts cardioprotection against I/R injury (IRI). Wistar rats were divided into the following six groups: control group (CON), I/R group, SAA+I/R group, ERK1/2 inhibitor PD098059+I/R group (PD+I/R), PD+SAA+I/R group, and JNK inhibitor SP600125+I/R group (SP+I/R). The cardioprotective effects of SAA on the myocardium during I/R were investigated with a Langendorff device. Heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), maximum rate of ventricular pressure rise and fall (±dp/dtmax), myocardial infarction areas (MIA), lactate dehydrogenase (LDH), and cardiomyocytes apoptosis were monitored. To determine the crosstalk betwee JNK and ERK1/2 via DUSP2/4/16 with SAA pretreatment, siRNA-DUSP2/4/16 were performed. The expression levels of Bcl-2, Bax, caspase 3, p-JNK, p-ERK1/2 and DUSP2/4/16 in cardiomyocytes were assayed by Western blot. Our results showed that LDH, MIA and cell apoptosis were decreased, and various parameters of heart function were improved by SAA pretreatment and SP application. In the I/R group, the expression levels of p-ERK1/2 and DUSP4/16 were not significantly different compared with the CON group, however, the protein expression levels of p-ERK1/2, Bcl-2 and DUSP4/16 were higher, while p-JNK, Bax, caspase 3 and DUSP2 levels were reduced among the SAA+I/R, PD+SAA+I/R and SP+I/R groups. The above indices were not significantly different between the SAA+I/R and SP+I/R groups. Compared with the SAA+I/R group, p-ERK1/2 was increased and p-JNK was decreased in the SAA+si-DUSP2+I/R, however, p-ERK was downregulated and p-JNK was upregulated in SAA+si-DUSP4+I

  2. A Three-Dimensional Simulation Model of Cardiomyocyte Integrating Excitation-Contraction Coupling and Metabolism

    PubMed Central

    Hatano, Asuka; Okada, Jun-ichi; Washio, Takumi; Hisada, Toshiaki; Sugiura, Seiryo

    2011-01-01

    Recent studies have revealed that Ca2+ not only regulates the contraction of cardiomyocytes, but can also function as a signaling agent to stimulate ATP production by the mitochondria. However, the spatiotemporal resolution of current experimental techniques limits our investigative capacity to understand this phenomenon. Here, we created a detailed three-dimensional (3D) cardiomyocyte model to study the subcellular regulatory mechanisms of myocardial energetics. The 3D cardiomyocyte model was based on the finite-element method, with detailed subcellular structures reproduced, and it included all elementary processes involved in cardiomyocyte electrophysiology, contraction, and ATP metabolism localized to specific loci. The simulation results were found to be reproducible and consistent with experimental data regarding the spatiotemporal pattern of cytosolic, intrasarcoplasmic-reticulum, and mitochondrial changes in Ca2+; as well as changes in metabolite levels. Detailed analysis suggested that although the observed large cytosolic Ca2+ gradient facilitated uptake by the mitochondrial Ca2+ uniporter to produce cyclic changes in mitochondrial Ca2+ near the Z-line region, the average mitochondrial Ca2+ changes slowly. We also confirmed the importance of the creatine phosphate shuttle in cardiac energy regulation. In summary, our 3D model provides a powerful tool for the study of cardiac function by overcoming some of the spatiotemporal limitations of current experimental approaches. PMID:22261047

  3. Single-cell transcriptome and epigenomic reprogramming of cardiomyocyte-derived cardiac progenitor cells

    PubMed Central

    Chen, Xin; Chakravarty, Tushar; Zhang, Yiqiang; Li, Xiaojin; Zhong, Jiang F.; Wang, Charles

    2016-01-01

    The molecular basis underlying the dedifferentiation of mammalian adult cardiomyocytes (ACMs) into myocyte-derived cardiac progenitor cells (mCPCs) during cardiac tissue regeneration is poorly understood. We present data integrating single-cell transcriptome and whole-genome DNA methylome analyses of mouse mCPCs to understand the epigenomic reprogramming governing their intrinsic cellular plasticity. Compared to parental cardiomyocytes, mCPCs display epigenomic reprogramming with many differentially-methylated regions, both hypermethylated and hypomethylated, across the entire genome. Correlating well with the methylome, our single-cell transcriptomic data show that the genes encoding cardiac structure and function proteins are remarkably down-regulated in mCPCs, while those for cell cycle, proliferation, and stemness are significantly up-regulated. In addition, implanting mCPCs into infarcted mouse myocardium improves cardiac function with augmented left ventricular ejection fraction. This dataset suggests that the cellular plasticity of mammalian cardiomyocytes is the result of a well-orchestrated epigenomic reprogramming and a subsequent global transcriptomic alteration. Understanding cardiomyocyte epigenomic reprogramming may enable the design of future clinical therapies that induce cardiac regeneration, and prevent heart failure. PMID:27622691

  4. Astragalus polysaccharide restores autophagic flux and improves cardiomyocyte function in doxorubicin-induced cardiotoxicity

    PubMed Central

    Cao, Yuan; Shen, Tao; Huang, Xiuqing; Lin, Yajun; Chen, Beidong; Pang, Jing; Li, Guoping; Wang, Que; Zohrabian, Sylvia; Duan, Chao; Ruan, Yang; Man, Yong; Wang, Shu; Li, Jian

    2017-01-01

    Doxorubicin (adriamycin), an anthracycline antibiotic, is commonly used to treat many types of solid and hematological malignancies. Unfortunately, clinical usage of doxorubicin is limited due to the associated acute and chronic cardiotoxicity. Previous studies demonstrated that Astragalus polysaccharide (APS), the extracts of Astragalus membranaceus, had strong anti-tumor activities and anti-inflammatory effects. However, whether APS could mitigate chemotherapy-induced cardiotoxicity is unclear thus far. We used a doxorubicin-induced neonatal rat cardiomyocyte injury model and a mouse heart failure model to explore the function of APS. GFP-LC3 adenovirus-mediated autophagic vesicle assays, GFP and RFP tandemly tagged LC3 (tfLC3) assays and Western blot analyses were performed to analyze the cell function and cell signaling changes following APS treatment in cardiomyocytes. First, doxorubicin treatment led to C57BL/6J mouse heart failure and increased cardiomyocyte apoptosis, with a disturbed cell autophagic flux. Second, APS restored autophagy in doxorubicin-treated primary neonatal rat ventricular myocytes and in the doxorubicin-induced heart failure mouse model. Third, APS attenuated doxorubicin-induced heart injury by regulating the AMPK/mTOR pathway. The mTOR inhibitor rapamycin significantly abrogated the protective effect of APS. These results suggest that doxorubicin could induce heart failure by disturbing cardiomyocyte autophagic flux, which may cause excessive cell apoptosis. APS could restore normal autophagic flux, ameliorating doxorubicin-induced cardiotoxicity by regulating the AMPK/mTOR pathway. PMID:27902477

  5. Impact of mitochondria on nitrite metabolism in HL-1 cardiomyocytes

    PubMed Central

    Dungel, Peter; Teuschl, Andreas H.; Banerjee, Asmita; Paier-Pourani, Jamile; Redl, Heinz; Kozlov, Andrey V.

    2013-01-01

    Apart from ATP synthesis mitochondria have many other functions, one being nitrite reductase activity. Nitric oxide (NO) released from nitrite has been shown to protect the heart from ischemia/reperfusion (I/R) injury in a cGMP-dependent manner. However, the exact impact of mitochondria on the release of NO from nitrite in cardiomyocytes is not completely understood. Besides mitochondria, a number of non-mitochondrial metalloproteins have been suggested to facilitate this process. The aim of this study was to investigate the impact of mitochondria on the bioactivation of nitrite in HL-1 cardiomyocytes. The levels of nitrosyl complexes of hemoglobin (NO-Hb) and cGMP levels were measured by electron spin resonance spectroscopy and enzyme immunoassay. In addition the formation of free NO was determined by confocal microscopy as well as intracellular nitrite and S-nitrosothiols by chemoluminescence analysis. NO was released from nitrite in cell culture in an oxygen-dependent manner. Application of specific inhibitors of the respiratory chain, p450, NO synthases (NOS) and xanthine oxidoreductase (XOR) showed that all four enzymatic systems are involved in the release of NO, but more than 50% of NO is released via the mitochondrial pathway. Only NO released by mitochondria activated cGMP synthesis. Cardiomyocytes co-cultured with red blood cells (RBC) competed with RBC for nitrite, but free NO was detected only in HL-1 cells suggesting that RBC are not a source of NO in this model. Apart from activation of cGMP synthesis, NO formed in HL-1 cells diffused out of the cells and formed NO-Hb complexes. In addition nitrite was converted by HL-1 cells to S-nitrosyl complexes. In HL-1 cardiomyocytes, several enzymatic systems are involved in nitrite reduction to NO but only the mitochondrial pathway of NO release activates cGMP synthesis. Our data suggest that this pathway may be a key regulator of myocardial contractility especially under hypoxic conditions. PMID:23730288

  6. SIRT1 regulates the mouse gastric emptying and intestinal growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study addressed physiological significance of SIRT1 gene on mouse gastrointestinal growth and function (gastric emptying and intestinal growth). SIRT1 (a NAD+-dependent histone deacetylase) is a key cellular energy sensor, and involved in a wide variety of cellular functions including energy me...

  7. Signaling pathways regulating cartilage growth plate formation and activity.

    PubMed

    Samsa, William E; Zhou, Xin; Zhou, Guang

    2017-02-01

    The growth plate is a highly specialized and dynamic cartilage structure that serves many essential functions in skeleton patterning, growth and endochondral ossification in developing vertebrates. Major signaling pathways initiated by classical morphogens and by other systemic and tissue-specific factors are intimately involved in key aspects of growth plate development. As a corollary of these essential functions, disturbances in these pathways due to mutations or environmental factors lead to severe skeleton disorders. Here, we review these pathways and the most recent progress made in understanding their roles in chondrocyte differentiation in growth plate development and activity. Furthermore, we discuss newly uncovered pathways involved in growth plate formation, including mTOR, the circadian clock, and the COP9 signalosome.

  8. Temporal changes in integrin-mediated cardiomyocyte adhesion secondary to chronic cardiac volume overload in rats

    PubMed Central

    Stewart, James A.; Gardner, Jason D.; Brower, Gregory L.

    2013-01-01

    Previous studies have established integrins as cell surface receptors that mediate cardiomyocyte-extracellular matrix (ECM) attachments. This study sought to determine the contributions of the myocardial β1- and β3-integrin subunits to ventricular dilatation and coronary flow regulation using a blood-perfused isolated heart preparation. Furthermore, cardiomyocyte adhesion to collagen types I and IV, fibronectin, and laminin with and without a β1-integrin subunit neutralizing antibody was assessed during the course of remodeling secondary to a sustained cardiac volume overload, including the onset of heart failure. Isolated cardiomyocytes were obtained during the initial, compensated, and decompensated phases of remodeling resulting from an aortocaval fistula created in 8-wk-old male Sprague-Dawley rats. Blocking the β1-integrin subunit in isolated normal hearts produced ventricular dilatation, whereas this was not the case when the β3-subunit was blocked. Substantial reductions in cardiomyocyte adhesion coincided with the previously documented development of ventricular dilatation and decreased contractility postfistula, with the β1-integrin contribution to adhesion ranging from 28% to 73% over the course of remodeling being essentially substrate independent. In contrast, both integrin subunits were found to be involved in regulating coronary vascular resistance. It is concluded that marked reductions in integrin-mediated cardiomyocyte adhesion to the ECM play a significant role in the progression of adverse myocardial remodeling that leads to heart failure. Furthermore, although both the β1- and β3-integrin subunits were involved in regulating coronary vascular resistance, only inhibition of β1-integrin-mediated adhesion resulted in ventricular dilatation of the normal heart. PMID:24163072

  9. Role of oxytocin/oxytocin receptor system in regulation of cell growth and neoplastic processes.

    PubMed

    Strunecká, A; Hynie, S; Klenerová, V

    2009-01-01

    Novel sites of oxytocin receptor expression have recently been detected in central nervous system, cardiomyocytes, endothelial cells, various carcinoma cells, etc. These and other discoveries have greatly expanded the classical biological roles of oxytocin, which are stimulation of uterine smooth muscle contraction at parturition and milk ejection during lactation. It is becoming clear that the great diversity of oxytocin actions in the brain and peripheral organs is paralleled by activation of a diversity of signalling pathways. On the other hand, until now only one single oxytocin receptor type has been detected. This receptor belongs to G protein-coupled receptors and in dependence on cell conditions it binds to different G proteins; this phenomenon is called receptor-G protein promiscuity. Thus, in the same cells oxytocin can activate multiple responses at the same time. Recently, the oxytocinergic system has also been implicated in the growth modulation of various neoplastic cells, where it may inhibit or stimulate cell proliferation in dependence on cell type and activated metabolic pathways. The discovery of novel oxytocin receptor-linked signalling cascades brings interesting knowledge opening new avenues for research in oncology and molecular pharmacology with perspectives of finding new therapeutic agents.

  10. Negative elongation factor controls energy homeostasis in cardiomyocytes.

    PubMed

    Pan, Haihui; Qin, Kunhua; Guo, Zhanyong; Ma, Yonggang; April, Craig; Gao, Xiaoli; Andrews, Thomas G; Bokov, Alex; Zhang, Jianhua; Chen, Yidong; Weintraub, Susan T; Fan, Jian-Bing; Wang, Degeng; Hu, Yanfen; Aune, Gregory J; Lindsey, Merry L; Li, Rong

    2014-04-10

    Negative elongation factor (NELF) is known to enforce promoter-proximal pausing of RNA polymerase II (Pol II), a pervasive phenomenon observed across multicellular genomes. However, the physiological impact of NELF on tissue homeostasis remains unclear. Here, we show that whole-body conditional deletion of the B subunit of NELF (NELF-B) in adult mice results in cardiomyopathy and impaired response to cardiac stress. Tissue-specific knockout of NELF-B confirms its cell-autonomous function in cardiomyocytes. NELF directly supports transcription of those genes encoding rate-limiting enzymes in fatty acid oxidation (FAO) and the tricarboxylic acid (TCA) cycle. NELF also shares extensively transcriptional target genes with peroxisome proliferator-activated receptor α (PPARα), a master regulator of energy metabolism in the myocardium. Mechanistically, NELF helps stabilize the transcription initiation complex at the metabolism-related genes. Our findings strongly indicate that NELF is part of the PPARα-mediated transcription regulatory network that maintains metabolic homeostasis in cardiomyocytes.

  11. Antizyme (AZ) regulates intestinal cell growth independently of polyamines

    PubMed Central

    Ray, Ramesh M.; Bhattacharya, Sujoy; Bavaria, Mitul N.; Viar, Mary Jane; Johnson, Leonard R.

    2014-01-01

    Since antizyme (AZ) is known to inhibit cell proliferation and to increase apoptosis, the question arises as to whether these effects occur independently of polyamines. Intestinal epithelial cells (IEC-6) were grown in control medium and medium containing 5mM difluoromethylornithine (DFMO) to inhibit ODC, DFMO + 5μM spermidine (SPD), DFMO+ 5μM spermine (SPM), or DFMO+ 10 μM putrescine (PUT) for 4 days and various parameters of growth were measured along with AZ levels. Cell counts were significantly decreased and mean doubling times were significantly increased by DFMO. Putrescine restored growth in the presence of DFMO. However, both SPD and SPM when added with DFMO caused a much greater inhibition of growth than did DFMO alone, and both of these polyamines caused a dramatic increase in AZ. The addition of SPD or SPM to media containing DFMO + PUT significantly inhibited growth and caused a significant increase in AZ. IEC-6 cells transfected with AZ-siRNA grew more than twice as rapidly as either control cells or those incubated with DFMO, indicating that removal of AZ increases growth in cells in which polyamine synthesis is inhibited as well as in control cells. In a separate experiment the addition of SPD increased AZ levels and inhibited growth of cells incubated with DFMO by 50%. The addition of 10 mM asparagine (ASN) prevented the increase in AZ and restored growth to control levels. These results show that cell growth in the presence or absence of ODC activity and in the presence or absence of polyamines depends only on the levels of AZ. Therefore, the effects of AZ on cell growth are independent of polyamines. PMID:24930035

  12. Ecdysone promotes growth of imaginal discs through the regulation of Thor in D. melanogaster

    PubMed Central

    Herboso, Leire; Oliveira, Marisa M.; Talamillo, Ana; Pérez, Coralia; González, Monika; Martín, David; Sutherland, James D.; Shingleton, Alexander W.; Mirth, Christen K.; Barrio, Rosa

    2015-01-01

    Animals have a determined species-specific body size that results from the combined action of hormones and signaling pathways regulating growth rate and duration. In Drosophila, the steroid hormone ecdysone controls developmental transitions, thereby regulating the duration of the growth period. Here we show that ecdysone promotes the growth of imaginal discs in mid-third instar larvae, since imaginal discs from larvae with reduced or no ecdysone synthesis are smaller than wild type due to smaller and fewer cells. We show that insulin-like peptides are produced and secreted normally in larvae with reduced ecdysone synthesis, and upstream components of insulin/insulin-like signaling are activated in their discs. Instead, ecdysone appears to regulate the growth of imaginal discs via Thor/4E-BP, a negative growth regulator downstream of the insulin/insulin-like growth factor/Tor pathways. Discs from larvae with reduced ecdysone synthesis have elevated levels of Thor, while mutations in Thor partially rescue their growth. The regulation of organ growth by ecdysone is evolutionarily conserved in hemimetabolous insects, as shown by our results obtained using Blattella germanica. In summary, our data provide new insights into the relationship between components of the insulin/insulin-like/Tor and ecdysone pathways in the control of organ growth. PMID:26198204

  13. Microarray and functional analysis of growth phase-dependent gene regulation in Bordetella bronchiseptica.

    PubMed

    Nicholson, Tracy L; Buboltz, Anne M; Harvill, Eric T; Brockmeier, Susan L

    2009-10-01

    Growth phase-dependent gene regulation has recently been demonstrated to occur in Bordetella pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived from a Bordetella bronchiseptica-like ancestor, we hypothesized that growth phase-dependent gene regulation would also occur in B. bronchiseptica. Microarray analysis revealed and quantitative real-time PCR (qRT-PCR) confirmed that growth phase-dependent gene regulation occurs in B. bronchiseptica, resulting in prominent temporal shifts in global gene expression. Two virulence phenotypes associated with these gene expression changes were tested. We found that growth-dependent increases in expression of some type III secretion system (TTSS) genes led to a growth phase-dependent increase in a TTSS-dependent function, cytotoxicity. Although the transcription of genes encoding adhesins previously shown to mediate adherence was decreased in late-log and stationary phases, we found that the adherence of B. bronchiseptica did not decrease in these later phases of growth. Microarray analysis revealed and qRT-PCR confirmed that growth phase-dependent gene regulation occurred in both Bvg(+) and Bvg(-) phase-locked mutants, indicating that growth phase-dependent gene regulation in B. bronchiseptica can function independently from the BvgAS regulatory system.

  14. Transforming growth factor beta regulates thyroid growth. Role in the pathogenesis of nontoxic goiter.

    PubMed Central

    Grubeck-Loebenstein, B; Buchan, G; Sadeghi, R; Kissonerghis, M; Londei, M; Turner, M; Pirich, K; Roka, R; Niederle, B; Kassal, H

    1989-01-01

    The production and growth regulatory activity of transforming growth factor beta were studied in human thyroid tissue. As estimated by its mRNA expression in fresh tissue samples, transforming growth factor beta was produced in normal and in diseased thyroid glands. Transforming growth factor beta mRNA was mainly produced by thyroid follicular cells and in lesser quantities by thyroid infiltrating mononuclear cells. The concentrations of transforming growth factor beta mRNA were lower in iodine-deficient nontoxic goiter than in Graves' disease and normal thyroid tissue. Transforming growth factor beta protein secretion by cultured thyroid follicular cells was also low in nontoxic goiter, but could be increased by addition of sodium iodide (10 microM) to the culture medium. Recombinant transforming growth factor beta did not affect basal tritiated thymidine incorporation in cultured thyroid follicular cells, but inhibited, at a concentration of 10 ng/ml, the growth stimulatory influence of insulin-like growth factor I, epidermal growth factor, transforming growth factor alpha, TSH, and partly that of normal human serum on cultured thyroid follicular cells. This inhibition was greater in Graves' disease than in nontoxic goiter. These results suggest that transforming growth factor beta may act as an autocrine growth inhibitor on thyroid follicular cells. Decreased transforming growth factor beta production and decreased responsiveness to transforming growth factor beta may be cofactors in the pathogenesis of iodine-deficient nontoxic goiter. Images PMID:2921318

  15. CaMKIIδ meditates phenylephrine induced cardiomyocyte hypertrophy through store-operated Ca(2+) entry.

    PubMed

    Ji, Yawei; Guo, Xin; Zhang, Zhe; Huang, Zhuyun; Zhu, Jianghua; Chen, Qing-Hui; Gui, Le

    Evidence suggests that store-operated Ca2+ entry (SOCE) is involved in the hypertrophy of cardiomyocytes. The signaling mechanisms of SOCE contributing to cardiac hypertrophy following phenylephrine (PE) stimulation are not fully understood. Ca(2+)/calmodulin-dependent protein kinase II δ (CaMKIIδ) plays an important role in regulating intracellular Ca(2+) hemostasis and function in the cardimyocytes. This study is aimed to determine the role of CaMKIIδ in regulating the PE-induced myocardial hypertrophy and the associated molecular signaling mechanisms. We used primary cultures of neonatal cardimyocytes isolated from the left ventricle of Sprague Dawley rats to investigate the effects of CaMKIIδ on myocardial hypertrophy and intracellular Ca(2+) mobilization. We found that the expression of CaMKIIδ was enhanced in PE-induced hypertrophic cardiomyocytes. CaMKIIδ siRNA, CaMKII inhibitor KN93, and SOCE blocker BTP2 attenuated the increase in the expression of CaMKIIδ and normalized the hypertrophic markers, atrial natriuretic peptide and brain natriuretic peptide, and size of cardiomyocytes induced by PE stimulation. The protein level of stromal interaction molecule 1 and Orai1, the essential components of the SOCE, is also enhanced in hypertrophic cardiomyocytes, which were normalized by CaMKIIδ siRNA and KN93 treatment. Hypertrophic cardiomyocytes showed an increase in the peak of Ca(2+) transient following store depletion, which was inhibited by SOCE blocker BTP2, CaMKIIδ siRNA, and KN93. The Ca(2+) currents through Ca(2+) release-activated Ca(2+) channels were increased in PE-treated cardiomyocytes and were attenuated by CaMKIIδ siRNA and KN93. These data indicate that PE-induced myocardial hypertrophy requires a complex signaling pathway that involves activation of both CaMKIIδ and SOCE. In conclusion, these studies reveal that up-regulation of CaMKIIδ may contribute to the PE-induced myocardial hypertrophy through the activation of SOCE expressed in

  16. Skeletal muscle-derived progenitors capable of differentiating into cardiomyocytes proliferate through myostatin-independent TGF-{beta} family signaling

    SciTech Connect

    Nomura, Tetsuya; Ueyama, Tomomi; Ashihara, Eishi; Tateishi, Kento; Asada, Satoshi; Nakajima, Norio; Isodono, Koji; Takahashi, Tomosaburo; Matsubara, Hiroaki Oh, Hidemasa

    2008-01-25

    The existence of skeletal muscle-derived stem cells (MDSCs) has been suggested in mammals; however, the signaling pathways controlling MDSC proliferation remain largely unknown. Here we report the isolation of myosphere-derived progenitor cells (MDPCs) that can give rise to beating cardiomyocytes from adult skeletal muscle. We identified that follistatin, an antagonist of TGF-{beta} family members, was predominantly expressed in MDPCs, whereas myostatin was mainly expressed in myogenic cells and mature skeletal muscle. Although follistatin enhanced the replicative growth of MDPCs through Smad2/3 inactivation and cell cycle progression, disruption of myostatin did not increase the MDPC proliferation. By contrast, inhibition of activin A (ActA) or growth differentiation factor 11 (GDF11) signaling dramatically increased MDPC proliferation via down-regulation of p21 and increases in the levels of cdk2/4 and cyclin D1. Thus, follistatin may be an effective progenitor-enhancing agent neutralizing ActA and GDF11 signaling to regulate the growth of MDPCs in skeletal muscle.

  17. Microbial Growth at Ultraslow Rates: Regulation and Genetic Stability.

    DTIC Science & Technology

    1983-03-01

    this taxonomic range of eubacteria , and the understanding we have gained of underlying biochemical and genetic machineries, it is clear that any...to eubacteria and whose effects on mu and Y, in fact, made the Monod-type equations invalid as soon as they were eluci- dated to the level reached by...growth parameters. Thus, we sought specifically: 1) to find if there was a pattern of growth behavior at slow rates common among eubacteria ; 2) to

  18. Plant growth regulation of Bt-cotton through Bacillus species.

    PubMed

    Pindi, Pavan Kumar; Sultana, Tasleem; Vootla, Praveen Kumar

    2014-06-01

    Deccan plateau in India periodically experiences droughts due to irregular rain fall and the soil in many parts of the region is considered to be poor for farming. Plant growth promoting rhizobacteria are originally defined as root-colonizing bacteria, i.e., Bacillus that cause either plant growth promotion or biological control of plant diseases. The study aims at the isolation of novel Bacillus species and to assess the biotechnological potential of the novel species as a biofertilizer, with respect to their plant growth promoting properties as efficient phosphate-solubilizing bacteria. Seven different strains of Bacillus were isolated from cotton rhizosphere soil near boys' hostel of Palamuru University which belongs to Deccan plateau. Among seven isolated strains, Bacillus strain-7 has shown maximum support for good growth of eight cotton cultivars. This bacterial species is named Bacillus sp. PU-7 based on the phenotypic and phylogenetic analysis. Among eight cotton cultivars, Mahyco has shown high levels of IAA, proteins, chlorophyll, sugars and low level of proline. Efficacy of novel Bacillus sp. PU-7 with Mahyco cultivar has been checked experimentally at field level in four different cotton grown agricultural soils. The strains supported plant growth in almost all the cases, especially in the deep black soil, with a clear evidence of maximum plant growth by increased levels of phytohormone production and biochemical analysis, followed by shallow black soil. Hence, it is inferred that the novel isolate can be used as bioinoculant in the cotton fields.

  19. Angiotensin II regulates growth of the developing papillas ex vivo

    PubMed Central

    Song, Renfang; Preston, Graeme; Khalili, Ali; El-Dahr, Samir S.

    2012-01-01

    We tested the hypothesis that lack of angiotensin (ANG) II production in angiotensinogen (AGT)-deficient mice or pharmacologic antagonism of ANG II AT1 receptor (AT1R) impairs growth of the developing papillas ex vivo, thus contributing to the hypoplastic renal medulla phenotype observed in AGT- or AT1R-null mice. Papillas were dissected from Hoxb7GFP+ or AGT+/+, +/−, −/− mouse metanephroi on postnatal day P3 and grown in three-dimentional collagen matrix gels in the presence of media (control), ANG II (10−5 M), or the specific AT1R antagonist candesartan (10−6 M) for 24 h. Percent reduction in papillary length was attenuated in AGT+/+ and in AGT+/− compared with AGT−/− (−18.4 ± 1.3 vs. −32.2 ± 1.6%, P < 0.05, −22.8 ± 1.3 vs. −32.2 ± 1.6%, P < 0.05, respectively). ANG II blunted the decrease in papilla length observed in respective media-treated controls in Hoxb7GFP+ (−1.5 ± 0.3 vs. −10.0 ± 1.4%, P < 0.05) or AGT+/+, +/−, and −/− papillas (−12.8 ± 0.7 vs. −18.4 ± 1.3%, P < 0.05, −16.8 ± 1.1 vs. −23 ± 1.2%, P < 0.05; −26.2 ± 1.6 vs. −32.2 ± 1.6%, P < 0.05, respectively). In contrast, percent decrease in the length of Hoxb7GFP+ papillas in the presence of the AT1R antagonist candesartan was higher compared with control (−24.3 ± 2.1 vs. −10.5 ± 1.8%, P < 0.05). The number of proliferating phospho-histone H3 (pH3)-positive collecting duct cells was lower, whereas the number of caspase 3-positive cells undergoing apoptosis was higher in candesartan- vs. media-treated papillas (pH3: 12 ± 1.4 vs. 21 ± 2.1, P < 0.01; caspase 3: 3.8 ± 0.5 vs. 1.7 ± 0.2, P < 0.01). Using quantitative RT-PCR, we demonstrate that AT1R signaling regulates the expression of genes implicated in morphogenesis of the renal medulla. We conclude that AT1R prevents shrinkage of the developing papillas observed ex vivo via control of Wnt7b, FGF7, β-catenin, calcineurin B1, and α3 integrin gene expression, collecting duct cell

  20. Connective Tissue Growth Factor Regulates Cardiac Function and Tissue Remodeling in a Mouse Model of Dilated Cardiomyopathy

    PubMed Central

    Koshman, Yevgeniya E.; Sternlicht, Mark D.; Kim, Taehoon; O'Hara, Christopher P.; Koczor, Christopher A.; Lewis, William; Seeley, Todd W.; Lipson, Kenneth E.; Samarel, Allen M.

    2015-01-01

    Cardiac structural changes associated with dilated cardiomyopathy (DCM) include cardiomyocyte hypertrophy and myocardial fibrosis. Connective Tissue Growth Factor (CTGF) has been associated with tissue remodeling and is highly expressed in failing hearts. Our aim was to test if inhibition of CTGF would alter the course of cardiac remodeling and preserve cardiac function in the protein kinase Cε (PKCε) mouse model of DCM. Transgenic mice expressing constitutively active PKCε in cardiomyocytes develop cardiac dysfunction that was evident by 3 months of age, and that progressed to cardiac fibrosis, heart failure, and increased mortality. Beginning at 3 months of age, PKCε mice were treated with a neutralizing monoclonal antibody to CTGF (FG-3149) for an additional 3 months. CTGF inhibition significantly improved left ventricular (LV) systolic and diastolic function in PKCε mice, and slowed the progression of LV dilatation. Using gene arrays and quantitative PCR, the expression of many genes associated with tissue remodeling were elevated in PKCε mice, but significantly decreased by CTGF inhibition. However total collagen deposition was not attenuated. The observation of significantly improved LV function by CTGF inhibition in PKCε mice suggests that CTGF inhibition may benefit patients with DCM. Additional studies to explore this potential are warranted. PMID:26549358

  1. Regulation of neuronal growth cone filopodia by nitric oxide.

    PubMed

    Van Wagenen, S; Rehder, V

    1999-05-01

    Nitric oxide (NO) has been proposed to play an important role during neuronal development. Since many of its effects occur during the time of growth cone pathfinding and target interaction, we here test the hypothesis that part of NO's effects might be exerted at the growth cone. We found that low concentrations of the NO-donors DEA/NO, SIN-1, and SNP caused a rapid and transient elongation of filopodia as well as a reduction in filopodial number. These effects resulted from distinct changes in filopodial extension and retraction rates. Our novel findings suggest that NO could play a physiological role by temporarily changing a growth cone's morphology and switching its behavior from a close-range to a long-range exploratory mode. We subsequently dissected the pathway by which NO acted on growth cones. The effect of NO donors on filopodial length could be blocked by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, an inhibitor of soluble guanylyl cyclase (sGC), indicating that NO acted via sGC. Supporting this idea, injection of cyclic GMP (cGMP) mimicked the effect of NO donors on growth cone filopodia. Moreover, application of NO-donors as well as injection of cGMP elicited a rapid and transient rise in intracellular calcium in growth cones, indicating that NO acted via cGMP to elevate calcium. This calcium rise, as well as the morphological effects of SIN-1 on filopodia, were blocked by preventing calcium entry. Given the role of filopodia in axonal guidance, our new data suggest that NO could function at the neuronal growth cone as an intracellular and/or intercellular signaling molecule by affecting steering decisions during neuronal pathfinding.

  2. Heme Oxygenase-1/Carbon Monoxide System and Embryonic Stem Cell Differentiation and Maturation into Cardiomyocytes

    PubMed Central

    Suliman, Hagir B.; Zobi, Fabio

    2016-01-01

    Abstract Aims: The differentiation of embryonic stem (ES) cells into energetically efficient cardiomyocytes contributes to functional cardiac repair and is envisioned to ameliorate progressive degenerative cardiac diseases. Advanced cell maturation strategies are therefore needed to create abundant mature cardiomyocytes. In this study, we tested whether the redox-sensitive heme oxygenase-1/carbon monoxide (HO-1/CO) system, operating through mitochondrial biogenesis, acts as a mechanism for ES cell differentiation and cardiomyocyte maturation. Results: Manipulation of HO-1/CO to enhance mitochondrial biogenesis demonstrates a direct pathway to ES cell differentiation and maturation into beating cardiomyocytes that express adult structural markers. Targeted HO-1/CO interventions up- and downregulate specific cardiogenic transcription factors, transcription factor Gata4, homeobox protein Nkx-2.5, heart- and neural crest derivatives-expressed protein 1, and MEF2C. HO-1/CO overexpression increases cardiac gene expression for myosin regulatory light chain 2, atrial isoform, MLC2v, ANP, MHC-β, and sarcomere α-actinin and the major mitochondrial fusion regulators, mitofusin 2 and MICOS complex subunit Mic60. This promotes structural mitochondrial network expansion and maturation, thereby supporting energy provision for beating embryoid bodies. These effects are prevented by silencing HO-1 and by mitochondrial reactive oxygen species scavenging, while disruption of mitochondrial biogenesis and mitochondrial DNA depletion by loss of mitochondrial transcription factor A compromise infrastructure. This leads to failure of cardiomyocyte differentiation and maturation and contractile dysfunction. Innovation: The capacity to augment cardiomyogenesis via a defined mitochondrial pathway has unique therapeutic potential for targeting ES cell maturation in cardiac disease. Conclusion: Our findings establish the HO-1/CO system and redox regulation of mitochondrial biogenesis as

  3. Repair Injured Heart by Regulating Cardiac Regenerative Signals

    PubMed Central

    Wang, Lei; Paul, Christian

    2016-01-01

    Cardiac regeneration is a homeostatic cardiogenic process by which the sections of malfunctioning adult cardiovascular tissues are repaired and renewed employing a combination of both cardiomyogenesis and angiogenesis. Unfortunately, while high-quality regeneration can be performed in amphibians and zebrafish hearts, mammalian hearts do not respond in kind. Indeed, a long-term loss of proliferative capacity in mammalian adult cardiomyocytes in combination with dysregulated induction of tissue fibrosis impairs mammalian endogenous heart regenerative capacity, leading to deleterious cardiac remodeling at the end stage of heart failure. Interestingly, several studies have demonstrated that cardiomyocyte proliferation capacity is retained in mammals very soon after birth, and cardiac regeneration potential is correspondingly preserved in some preadolescent vertebrates after myocardial infarction. There is therefore great interest in uncovering the molecular mechanisms that may allow heart regeneration during adult stages. This review will summarize recent findings on cardiac regenerative regulatory mechanisms, especially with respect to extracellular signals and intracellular pathways that may provide novel therapeutics for heart diseases. Particularly, both in vitro and in vivo experimental evidences will be presented to highlight the functional role of these signaling cascades in regulating cardiomyocyte proliferation, cardiomyocyte growth, and maturation, with special emphasis on their responses to heart tissue injury. PMID:27799944

  4. ROCK1/p53/NOXA signaling mediates cardiomyocyte apoptosis in response to high glucose in vitro and vivo.

    PubMed

    Su, Dongmei; Guan, Lina; Gao, Qianqian; Li, Qian; Shi, Cuige; Liu, Yi; Sun, Lei; Lu, Cailing; Ma, Xu; Zhao, Jing

    2017-04-01

    Gestational diabetes mellitus is a risk factor for congenital heart defects; however, the molecular basis of the congenital heart anomalies remains obscure. Previous reports showed a positive correlation between abnormal cardiomyocyte apoptosis and ventricular wall thinness, one type of congenital heart anomaly. This work explored the expression pattern and molecular mechanism of the Rho-associated coiled-coil containing protein kinase 1 (ROCK1) gene in cardiomyocyte apoptosis and genesis of ventricular wall thinness. In this report, we found a marked increase in the number of apoptotic cardiomyocytes in response to high glucose (HG) treatment. Moreover, up-regulation of ROCK1 expression observed in diabetic offspring compared with controls was potentially associated with cardiomyocyte apoptosis and the ventricular wall thinness. Further investigation showed that p53 and NOXA protein levels increased during ROCK1-meidated apoptosis in response to HG. In response to HG, whereby ROCK1 phosphorylated p53 at Ser15 to up-regulate its protein level. Furthermore, we found that p53 mediated the expression of NOXA during HG-induced apoptosis, and histone acetyltransferase p300 participated in this process. These findings reveal a novel regulatory mechanism of ROCK1/p53/NOXA signaling in modulating cardiomyocyte apoptosis in vitro and maternal diabetes-induced congenital heart defects in vivo.

  5. Analysis of cardiomyocyte movement in the developing murine heart

    SciTech Connect

    Hashimoto, Hisayuki; Yuasa, Shinsuke; Tabata, Hidenori; Tohyama, Shugo; Seki, Tomohisa; Egashira, Toru; Hayashiji, Nozomi; Hattori, Fumiyuki; Kusumoto, Dai; Kunitomi, Akira; Takei, Makoto; Kashimura, Shin; Yozu, Gakuto; Shimojima, Masaya; Motoda, Chikaaki; Muraoka, Naoto; Nakajima, Kazunori; Sakaue-Sawano, Asako; Miyawaki, Atsushi; Fukuda, Keiichi

    2015-09-04

    The precise assemblage of several types of cardiac precursors controls heart organogenesis. The cardiac precursors show dynamic movement during early development and then form the complicated heart structure. However, cardiomyocyte movements inside the newly organized mammalian heart remain unclear. We previously established the method of ex vivo time-lapse imaging of the murine heart to study cardiomyocyte behavior by using the Fucci (fluorescent ubiquitination-based cell cycle indicator) system, which can effectively label individual G1, S/G2/M, and G1/S-transition phase nuclei in living cardiomyocytes as red, green, and yellow, respectively. Global analysis of gene expression in Fucci green positive ventricular cardiomyocytes confirmed that cell cycle regulatory genes expressed in G1/S, S, G2/M, and M phase transitions were upregulated. Interestingly, pathway analysis revealed that many genes related to the cell cycle were significantly upregulated in the Fucci green positive ventricular cardiomyocytes, while only a small number of genes related to cell motility were upregulated. Time-lapse imaging showed that murine proliferating cardiomyocytes did not exhibit dynamic movement inside the heart, but stayed on site after entering the cell cycle. - Highlights: • We directly visualized cardiomyocyte movement inside the developing murine heart. • Cell cycle related genes were upregulated in the proliferating cardiomyocytes. • Time-lapse imaging revealed that proliferating murine cardiomyocytes stayed in place. • Murine ventricular cardiomyocytes proliferate on site during development.

  6. TGF-β receptor type II costameric localization in cardiomyocytes and host cell TGF-β response is disrupted by Trypanosoma cruzi infection.

    PubMed

    Calvet, Claudia Magalhães; Silva, Tatiana Araújo; DE Melo, Tatiana Galvão; DE Araújo-Jorge, Tânia Cremonini; Pereira, Mirian Claudia DE Souza

    2016-05-01

    Transforming growth factor beta (TGF-β) cytokine is involved in Chagas disease establishment and progression. Since Trypanosoma cruzi can modulate host cell receptors, we analysed the TGF-β receptor type II (TβRII) expression and distribution during T. cruzi - cardiomyocyte interaction. TβRII immunofluorescent staining revealed a striated organization in cardiomyocytes, which was co-localized with vinculin costameres and enhanced (38%) after TGF-β treatment. Cytochalasin D induced a decrease of 45·3% in the ratio of cardiomyocytes presenting TβRII striations, demonstrating an association of TβRII with the cytoskeleton. Western blot analysis showed that cytochalasin D significantly inhibited Smad 2 phosphorylation and fibronectin stimulation after TGF-β treatment in cardiomyocytes. Trypanosoma cruzi infection elicited a decrease of 79·8% in the frequency of cardiomyocytes presenting TβRII striations, but did not interfere significantly in its expression. In addition, T. cruzi-infected cardiomyocytes present a lower response to exogenous TGF-β, showing no enhancement of TβRII striations and a reduction of phosphorylated Smad 2, with no significant difference in TβRII expression when compared to uninfected cells. Together, these results suggest that the co-localization of TβRII with costameres is important in activating the TGF-β signalling cascade, and that T. cruzi-derived cytoskeleton disorganization could result in altered or low TGF-β response in infected cardiomyocytes.

  7. NCS-1 differentially regulates growth cone and somata calcium channels in Lymnaea neurons.

    PubMed

    Hui, Kwokyin; Feng, Zhong-Ping

    2008-02-01

    Local voltage-gated calcium channels, which regulate intracellular Ca2+ levels by allowing Ca2+ influx, play an important role in guiding and shaping growth cones, and in regulating the outgrowth and branching of neurites. Therefore, elucidating the mechanisms that regulate the biophysical properties of whole-cell calcium currents in the growth cones and somata of growing neurons is important to improving our understanding of neuronal development and regeneration. In this study, taking advantage of the large size of the pedal A (PeA) neurons in Lymnaea stagnalis, we compared the biophysical properties of somata and growth cone whole-cell calcium channel currents using Ba2+ and Ca2+ as current carriers. We found that somata and growth cone currents exhibit similar high-voltage activation properties. However, Ba2+ and Ca2+ currents in growth cones and somata are differentially affected by a dominant-negative peptide containing the C-terminal amino acid sequence of neuronal calcium sensor-1 (NCS-1). The peptide selectively reduces the peak and sustained components of current densities and the slope conductance in growth cones, and shifts the reversal potential of the growth cone currents to more hyperpolarized voltages. In contrast, the peptide had no significant effect on the somata calcium channels. Thus, we conclude that NCS-1 differentially modulates Ca2+ currents in the somata and growth cones of regenerating neurons, and may serve as a key regulator to facilitate the growth cone calcium channel activity.

  8. Effect of Three Statins on Glucose Uptake of Cardiomyocytes and its Mechanism.

    PubMed

    Jiang, Zhenhuan; Yu, Bo; Li, Yang

    2016-08-11

    BACKGROUND The aim of this study was to investigate the effects of different statins on glucose uptake and to confirm its mechanism in primary cultured rat cardiomyocytes after administration of atorvastatin, pravastatin, and rosuvastatin. MATERIAL AND METHODS Primary cultured rat cardiomyocytes were randomly assigned to 5 groups: normal control group (OB), insulin group (S1), statin 1-μM (S2), 5-μM (S3), and 10-μM (S4) groups for 3 different statins. The 2-[3H]-DG uptake of each group was determined and the mRNA and protein expression levels of glucose transporter type 4 (GLUT4), insulin receptor substrate (IRs), and RhoA were assessed. RESULTS After treatment with different concentrations of statins and insulin, the 2-[3H]-DG uptake showed a significant negative correlation with the concentration of atorvastatin (P<0.05), and no significant correlation with pravastatin and rosuvastatin. The mRNA and protein expression levels of GLUT4 and IRs-1 in primary cultured cardiomyocytes were both significantly reduced by atorvastatin treatment (P<0.05). Pravastatin and rosuvastatin showed no significant effects on GLUT4 and IRs-1 expression. The mRNA and protein expression levels of RhoA both showed no significant difference when treated with the 3 statins. CONCLUSIONS These results confirm that atorvastatin can inhibit insulin-induced glucose uptake in primary cultured rat cardiomyocytes by regulating the PI3K/Akt insulin signal transduction pathway.

  9. Signalling of abscisic acid to regulate plant growth.

    PubMed Central

    Himmelbach, A; Iten, M; Grill, E

    1998-01-01

    Abscisic acid (ABA) mediated growth control is a fundamental response of plants to adverse environmental cues. The linkage between ABA perception and growth control is currently being unravelled by using different experimental approaches such as mutant analysis and microinjection experiments. So far, two protein phosphatases, ABI1 and ABI2, cADPR, pH, and Ca2+ have been identified as main components of the ABA signalling pathway. Here, the ABA signal transduction pathway is compared to signalling cascades from yeast and mammalian cells. A model for a bifurcated ABA signal transduction pathway exerting a positive and negative control mechanism is proposed. PMID:9800207

  10. AMPK regulation of the growth of cultured human keratinocytes

    SciTech Connect

    Saha, Asish K. . E-mail: aksaha@bu.edu; Persons, Kelly; Safer, Joshua D.; Luo Zhijun; Holick, Michael F.; Ruderman, Neil B.

    2006-10-20

    AMP kinase (AMPK) is a fuel sensing enzyme that responds to cellular energy depletion by increasing processes that generate ATP and inhibiting others that require ATP but are not acutely necessary for survival. In the present study, we examined the relationship between AMPK activation and the growth (proliferation) of cultured human keratinocytes and assessed whether the inhibition of keratinocyte growth by vitamin D involves AMPK activation. In addition, we explored whether the inhibition of keratinocyte proliferation as they approach confluence could be AMPK-related. Keratinocytes were incubated for 12 h with the AMPK activator, 5-aminoimidazole-4-carboxamide-1-{beta}-D-ribofuranoside (AICAR). At concentrations of 10{sup -4} and 10{sup -3} M, AICAR inhibited keratinocyte growth by 50% and 95%, respectively, based on measurements of thymidine incorporation into DNA. It also increased AMPK and acetyl CoA carboxylase phosphorylation (P-AMPK and P-ACC) and decreased the concentration of malonyl CoA confirming that AMPK activation had occurred. Incubation with the thiazolidinedione, troglitazone (10{sup -6} M) caused similar alterations in P-AMPK, P-ACC, and cell growth. In contrast, the well known inhibition of keratinocyte growth by 1,25-dihydroxyvitamin D{sub 3} (10{sup -7} and 10{sup -6} M) was not associated with changes in P-AMPK or P-ACC. Like most cells, the growth of keratinocytes diminished as they approached confluence. Thus, it was of note that we found a progressive increase in P-AMPK (1.5- to 2-fold, p < 0.05) as keratinocytes grown in control medium went from 25% to 100% confluence. In conclusion, the data are consistent with the hypothesis that activation of AMPK acts as a signal to diminish the proliferation of cultured keratinocytes as they approach confluence. They also suggest that AMPK activators, such as AICAR and troglitazone, inhibit keratinocyte growth and that the inhibition of cell growth by 1,25-dihydroxyvitamin D{sub 3} is AMPK-independent.

  11. Physical and biological regulation of neuron regenerative growth and network formation on recombinant dragline silks.

    PubMed

    An, Bo; Tang-Schomer, Min D; Huang, Wenwen; He, Jiuyang; Jones, Justin A; Lewis, Randolph V; Kaplan, David L

    2015-04-01

    Recombinant spider silks produced in transgenic goat milk were studied as cell culture matrices for neuronal growth. Major ampullate spidroin 1 (MaSp1) supported neuronal growth, axon extension and network connectivity, with cell morphology comparable to the gold standard poly-lysine. In addition, neurons growing on MaSp1 films had increased neural cell adhesion molecule (NCAM) expression at both mRNA and protein levels. The results indicate that MaSp1 films present useful surface charge and substrate stiffness to support the growth of primary rat cortical neurons. Moreover, a putative neuron-specific surface binding sequence GRGGL within MaSp1 may contribute to the biological regulation of neuron growth. These findings indicate that MaSp1 could regulate neuron growth through its physical and biological features. This dual regulation mode of MaSp1 could provide an alternative strategy for generating functional silk materials for neural tissue engineering.

  12. Genetic Regulation of Phenotypic Plasticity and Canalisation in Yeast Growth.

    PubMed

    Yadav, Anupama; Dhole, Kaustubh; Sinha, Himanshu

    2016-01-01

    The ability of a genotype to show diverse phenotypes in different environments is called phenotypic plasticity. Phenotypic plasticity helps populations to evade extinctions in novel environments, facilitates adaptation and fuels evolution. However, most studies focus on understanding the genetic basis of phenotypic regulation in specific environments. As a result, while it's evolutionary relevance is well established, genetic mechanisms regulating phenotypic plasticity and their overlap with the environment specific regulators is not well understood. Saccharomyces cerevisiae is highly sensitive to the environment, which acts as not just external stimulus but also as signalling cue for this unicellular, sessile organism. We used a previously published dataset of a biparental yeast population grown in 34 diverse environments and mapped genetic loci regulating variation in phenotypic plasticity, plasticity QTL, and compared them with environment-specific QTL. Plasticity QTL is one whose one allele exhibits high plasticity whereas the other shows a relatively canalised behaviour. We mapped phenotypic plasticity using two parameters-environmental variance, an environmental order-independent parameter and reaction norm (slope), an environmental order-dependent parameter. Our results show a partial overlap between pleiotropic QTL and plasticity QTL such that while some plasticity QTL are also pleiotropic, others have a significant effect on phenotypic plasticity without being significant in any environment independently. Furthermore, while some plasticity QTL are revealed only in specific environmental orders, we identify large effect plasticity QTL, which are order-independent such that whatever the order of the environments, one allele is always plastic and the other is canalised. Finally, we show that the environments can be divided into two categories based on the phenotypic diversity of the population within them and the two categories have differential regulators of

  13. Growth Phase dependent gene regulation in Bordetella bronchiseptica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bordetellae are Gram negative bacterial respiratory pathogens. Bordetella pertussis, the causative agent of whooping cough, is a human-restricted variant of Bordetella bronchiseptica, which infects a broad range of mammals causing chronic and often asymptomatic infections. Growth phase dependent gen...

  14. Cytokines and growth factors which regulate bone cell function

    NASA Astrophysics Data System (ADS)

    Seino, Yoshiki

    Everybody knows that growth factors are most important in making bone. Hormones enhance bone formation from a long distance. Growth factors promote bone formation as an autocrine or paracrine factor in nearby bone. BMP-2 through BMP-8 are in the TGF-β family. BMP makes bone by enchondral ossification. In bone, IGF-II is most abundant, second, TGF-β, and third IGF-I. TGF-β enhances bone formation mainly by intramembranous ossification in vivo. TGF-β affects both cell proliferation and differentiation, however, TGF-β mainly enhances bone formation by intramembranous ossification. Interestingly, TGF-β is increased by estrogen(E 2), androgen, vitamin D, TGF-β and FGF. IGF-I and IGF-II also enhance bone formation. At present it remains unclear why IGF-I is more active in bone formation than IGF-II, although IGF-II is more abundant in bone compared to IGF-I. However, if only type I receptor signal transduction promotes bone formation, the strong activity of IGF-I in bone formation is understandable. GH, PTH and E 2 promotes IGF-I production. Recent data suggest that hormones containing vitamin D or E 2 enhance bone formation through growth factors. Therefore, growth factors are the key to clarifying the mechanism of bone formation.

  15. Necdin, a negative growth regulator, is a novel STAT3 target gene down-regulated in human cancer.

    PubMed

    Haviland, Rachel; Eschrich, Steven; Bloom, Gregory; Ma, Yihong; Minton, Susan; Jove, Richard; Cress, W Douglas

    2011-01-01

    Cytokine and growth factor signaling pathways involving STAT3 are frequently constitutively activated in many human primary tumors, and are known for the transcriptional role they play in controlling cell growth and cell cycle progression. However, the extent of STAT3's reach on transcriptional control of the genome as a whole remains an important question. We predicted that this persistent STAT3 signaling affects a wide variety of cellular functions, many of which still remain to be characterized. We took a broad approach to identify novel STAT3 regulated genes by examining changes in the genome-wide gene expression profile by microarray, using cells expressing constitutively-activated STAT3. Using computational analysis, we were able to define the gene expression profiles of cells containing activated STAT3 and identify candidate target genes with a wide range of biological functions. Among these genes we identified Necdin, a negative growth regulator, as a novel STAT3 target gene, whose expression is down-regulated at the mRNA and protein levels when STAT3 is constitutively active. This repression is STAT3 dependent, since inhibition of STAT3 using siRNA restores Necdin expression. A STAT3 DNA-binding site was identified in the Necdin promoter and both EMSA and chromatin immunoprecipitation confirm binding of STAT3 to this region. Necdin expression has previously been shown to be down-regulated in a melanoma and a drug-resistant ovarian cancer cell line. Further analysis of Necdin expression demonstrated repression in a STAT3-dependent manner in human melanoma, prostate and breast cancer cell lines. These results suggest that STAT3 coordinates expression of genes involved in multiple metabolic and biosynthetic pathways, integrating signals that lead to global transcriptional changes and oncogenesis. STAT3 may exert its oncogenic effect by up-regulating transcription of genes involved in promoting growth and proliferation, but also by down-regulating expression

  16. Understanding Growth in Self-Regulation: International Contributions

    ERIC Educational Resources Information Center

    Morrison, Frederick J.

    2015-01-01

    Over the past decade or so, the importance of self-regulation for academic development and later life success has become increasingly clear (Morrison, Bachman, & Connor, 2005). This article is a commentary regarding the articles in a special issue of "Early Education and Development," which broaden the understanding of the important…

  17. The transcription factor MEF2C mediates cardiomyocyte hypertrophy induced by IGF-1 signaling

    SciTech Connect

    Munoz, Juan Pablo; Collao, Andres; Chiong, Mario; Maldonado, Carola; Adasme, Tatiana; Carrasco, Loreto; Ocaranza, Paula; Bravo, Roberto; Gonzalez, Leticia; Diaz-Araya, Guillermo; Hidalgo, Cecilia; Lavandero, Sergio

    2009-10-09

    Myocyte enhancer factor 2C (MEF2C) plays an important role in cardiovascular development and is a key transcription factor for cardiac hypertrophy. Here, we describe MEF2C regulation by insulin-like growth factor-1 (IGF-1) and its role in IGF-1-induced cardiac hypertrophy. We found that IGF-1 addition to cultured rat cardiomyocytes activated MEF2C, as evidenced by its increased nuclear localization and DNA binding activity. IGF-1 stimulated MEF2 dependent-gene transcription in a time-dependent manner, as indicated by increased MEF2 promoter-driven reporter gene activity; IGF-1 also induced p38-MAPK phosphorylation, while an inhibitor of p38-MAPK decreased both effects. Additionally, inhibitors of phosphatidylinositol 3-kinase and calcineurin prevented IGF-1-induced MEF2 transcriptional activity. Via MEF2C-dependent signaling, IGF-1 also stimulated transcription of atrial natriuretic factor and skeletal {alpha}-actin but not of fos-lux reporter genes. These novel data suggest that MEF2C activation by IGF-1 mediates the pro-hypertrophic effects of IGF-1 on cardiac gene expression.

  18. iPSC-derived cardiomyocytes reveal abnormal TGFβ signaling in left ventricular non-compaction cardiomyopathy

    PubMed Central

    Kodo, Kazuki; Ong, Sang-Ging; Jahanbani, Fereshteh; Termglinchan, Vittavat; Hirono, Keiichi; InanlooRahatloo, Kolsoum; Ebert, Antje D.; Shukla, Praveen; Abilez, Oscar J.; Churko, Jared M.; Karakikes, Ioannis; Jung, Gwanghyun; Ichida, Fukiko; Wu, Sean M.; Snyder, Michael P.; Bernstein, Daniel; Wu, Joseph C.

    2016-01-01

    Left ventricular non-compaction (LVNC) is the third most prevalent cardiomyopathy in children and its pathogenesis has been associated with the developmental defect of the embryonic myocardium. We show that patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from LVNC patients carrying a mutation in the cardiac transcription factor TBX20 recapitulate a key aspect of the pathological phenotype at the single-cell level and was associated with perturbed transforming growth factor beta (TGFβ) signaling. LVNC iPSC-CMs have decreased proliferative capacity due to abnormal activation of TGFβ signaling. TBX20 regulates the expression of TGFβ signaling modifiers including a known genetic cause of LVNC, PRDM16, and genome editing of PRDM16 caused proliferation defects in iPSC-CMs. Inhibition of TGFβ signaling and genome correction of the TBX20 mutation were sufficient to reverse the disease phenotype. Our study demonstrates that iPSC-CMs are a useful tool for the exploration of pathological mechanisms underlying poorly understood cardiomyopathies including LVNC. PMID:27642787

  19. Antagonistic growth regulation by Dpp and Fat drives uniform cell proliferation.

    PubMed

    Schwank, Gerald; Tauriello, Gerardo; Yagi, Ryohei; Kranz, Elizabeth; Koumoutsakos, Petros; Basler, Konrad

    2011-01-18

    We use the Dpp morphogen gradient in the Drosophila wing disc as a model to address the fundamental question of how a gradient of a growth factor can produce uniform growth. We first show that proper expression and subcellular localization of components in the Fat tumor-suppressor pathway, which have been argued to depend on Dpp activity differences, are not reliant on the Dpp gradient. We next analyzed cell proliferation in discs with uniformly high Dpp or uniformly low Fat signaling activity and found that these pathways regulate growth in a complementary manner. While the Dpp mediator Brinker inhibits growth in the primordium primarily in the lateral regions, Fat represses growth mostly in the medial region. Together, our results indicate that the activities of both signaling pathways are regulated in a parallel rather than sequential manner and that uniform proliferation is achieved by their complementary action on growth.

  20. Systems Level Regulation of Rhythmic Growth Rate and Biomass Accumulation in Grasses

    SciTech Connect

    Kay, Steve A.

    2013-05-02

    Several breakthroughs have been recently made in our understanding of plant growth and biomass accumulation. It was found that plant growth is rhythmically controlled throughout the day by the circadian clock through a complex interplay of light and phytohormone signaling pathways. While plants such as the C4 energy crop sorghum (Sorghum bicolor (L.) Moench) and possibly the C3 grass (Brachypodium distachyon) also exhibit daily rhythms in growth rate, the molecular details of its regulation remain to be explored. A better understanding of diurnally regulated growth behavior in grasses may lead to species-specific mechanisms highly relevant to future strategies to optimize energy crop biomass yield. Here we propose to devise a systems approach to identify, in parallel, regulatory hubs associated with rhythmic growth in C3 and C4 plants. We propose to use rhythmicity in daily growth patterns to drive the discovery of regulatory network modules controlling biomass accumulation.

  1. Target of rapamycin signaling regulates metabolism, growth, and lifespan in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    TOR is a major nutrition and energy sensor that regulates growth and lifespan in yeast and animals. In plants growth and lifespan are intertwined with not only nutrient acquisition but also nutrition generation and unique aspects of development and differentiation. How TOR functions in these process...

  2. Growth Regulator Herbicides Prevent Invasive Annual grass Seed Production Under Field Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth regulator herbicides, such as 2,4-D, dicamba, picloram, and aminopyralid, are commonly used to control broadleaf weeds in grasslands, non-croplands and cereal crops (e.g. wheat, barley). If applied to cereals at late growth stages, while the grasses are developing reproductive parts, the her...

  3. Microarray and functional analysis of growth-phase dependent gene regulation in Bordetella bronchiseptica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth-phase dependent gene regulation has recently been demonstrated to occur in B. pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived fro...

  4. Involvement of Rictor/mTORC2 in cardiomyocyte differentiation of mouse embryonic stem cells in vitro

    PubMed Central

    Zheng, Bei; Wang, Jiadan; Tang, Leilei; Tan, Chao; Zhao, Zhe; Xiao, Yi; Ge, Renshan; Zhu, Danyan

    2017-01-01

    Rictor is a key regulatory/structural subunit of the mammalian target of rapamycin complex 2 (mTORC2) and is required for phosphorylation of Akt at serine 473. It plays an important role in cell survival, actin cytoskeleton organization and other processes in embryogenesis. However, the role of Rictor/mTORC2 in the embryonic cardiac differentiation has been uncovered. In the present study, we examined a possible link between Rictor expression and cardiomyocyte differentiation of the mouse embryonic stem (mES) cells. Knockdown of Rictor by shRNA significantly reduced the phosphorylation of Akt at serine 473 followed by a decrease in cardiomyocyte differentiation detected by beating embryoid bodies. The protein levels of brachyury (mesoderm protein), Nkx2.5 (cardiac progenitor cell protein) and α-Actinin (cardiomyocyte biomarker) decreased in Rictor knockdown group during cardiogenesis. Furthermore, knockdown of Rictor specifically inhibited the ventricular-like cells differentiation of mES cells with reduced level of ventricular-specific protein, MLC-2v. Meanwhile, patch-clamp analysis revealed that shRNA-Rictor significantly increased the number of cardiomyocytes with abnormal electrophysiology. In addition, the expressions and distribution patterns of cell-cell junction proteins (Cx43/Desmoplakin/N-cadherin) were also affected in shRNA-Rictor cardiomyocytes. Taken together, the results demonstrated that Rictor/mTORC2 might play an important role in the cardiomyocyte differentiation of mES cells. Knockdown of Rictor resulted in inhibiting ventricular-like myocytes differentiation and induced arrhythmias symptom, which was accompanied by interfering the expression and distribution patterns of cell-cell junction proteins. Rictor/mTORC2 might become a new target for regulating cardiomyocyte differentiation and a useful reference for application of the induced pluripotent stem cells. PMID:28123351

  5. Emergence of robust growth laws from optimal regulation of ribosome synthesis.

    PubMed

    Scott, Matthew; Klumpp, Stefan; Mateescu, Eduard M; Hwa, Terence

    2014-08-22

    Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large-scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome-wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms.

  6. Emergence of robust growth laws from optimal regulation of ribosome synthesis

    PubMed Central

    Scott, Matthew; Klumpp, Stefan; Mateescu, Eduard M; Hwa, Terence

    2014-01-01

    Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large-scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome-wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms. PMID:25149558

  7. Nitric Oxide Synthase Regulates Growth Coordination During Drosophila melanogaster Imaginal Disc Regeneration.

    PubMed

    Jaszczak, Jacob S; Wolpe, Jacob B; Dao, Anh Q; Halme, Adrian

    2015-08-01

    Mechanisms that coordinate growth during development are essential for producing animals with proper organ proportion. Here we describe a pathway through which tissues communicate to coordinate growth. During Drosophila melanogaster larval development, damage to imaginal discs activates a regeneration checkpoint through expression of Dilp8. This both produces a delay in developmental timing and slows the growth of undamaged tissues, coordinating regeneration of the damaged tissue with developmental progression and overall growth. Here we demonstrate that Dilp8-dependent growth coordination between regenerating and undamaged tissues, but not developmental delay, requires the activity of nitric oxide synthase (NOS) in the prothoracic gland. NOS limits the growth of undamaged tissues by reducing ecdysone biosynthesis, a requirement for imaginal disc growth during both the regenerative checkpoint and normal development. Therefore, NOS activity in the prothoracic gland coordinates tissue growth through regulation of endocrine signals.

  8. Phospholipase C-epsilon augments epidermal growth factor-dependent cell growth by inhibiting epidermal growth factor receptor down-regulation.

    PubMed

    Yun, Sanguk; Hong, Won-Pyo; Choi, Jang Hyun; Yi, Kye Sook; Chae, Suhn-Kee; Ryu, Sung Ho; Suh, Pann-Ghill

    2008-01-04

    The down-regulation of the epidermal growth factor (EGF) receptor is critical for the termination of EGF-dependent signaling, and the dysregulation of this process can lead to oncogenesis. In the present study, we suggest a novel mechanism for the regulation of EGF receptor down-regulation by phospholipase C-epsilon. The overexpression of PLC-epsilon led to an increase in receptor recycling and decreased the down-regulation of the EGF receptor in COS-7 cells. Adaptor protein complex 2 (AP2) was identified as a novel binding protein that associates with the PLC-epsilon RA2 domain independently of Ras. The interaction of PLC-epsilon with AP2 was responsible for the suppression of EGF receptor down-regulation, since a perturbation in this interaction abolished this effect. Enhanced EGF receptor stability by PLC-epsilon led to the potentiation of EGF-dependent growth in COS-7 cells. Finally, the knockdown of PLC-epsilon in mouse embryo fibroblast cells elicited a severe defect in EGF-dependent growth. Our results indicated that PLC-epsilon could promote EGF-dependent cell growth by suppressing receptor down-regulation.

  9. Live cardiomyocyte imaging via hybrid TPEF-SHG microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Honghai; Qin, Wan; Shao, Yonghong; Liu, Qiuying; Ma, Zhen; Borg, Thomas K.; Gao, Bruce Z.

    2012-03-01

    Utilizing a custom-built, on-stage incubator-combined, two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) imaging system, we observed new-sarcomere addition in rat neonatal cardiomyocytes during 10 hours of on-stage incubation. This addition occurred at one end of an existing myofibril, the sides of existing myofibrils, and at the interstice of several separated myofibrils; in the cases of the latter two, we observed mature myofibrils acting as templates. We found that during sarcomeric addition, myosin filaments are assembled onto the premyofibril laterally. This lateral addition, which proceeds stepwise along the axial direction, plays an important role in the accumulation of Z-bodies to form mature Z-disks and in the regulation of sarcomeric length during maturation.

  10. Elastic interactions synchronize beating in cardiomyocytes.

    PubMed

    Cohen, Ohad; Safran, Samuel A

    2016-07-13

    Motivated by recent experimental results, we study theoretically the synchronization of the beating phase and frequency of two nearby cardiomyocyte cells. Each cell is represented as an oscillating force dipole in an infinite, viscoelastic medium and the propagation of the elastic signal within the medium is predicted. We examine the steady-state beating of two nearby cells, and show that elastic interactions result in forces that synchronize the phase and frequency of beating in a manner that depends on their mutual orientation. The theory predicts both in-phase and anti-phase steady-state beating depending on the relative cell orientations, as well as how synchronized beating varies with substrate elasticity and the inter-cell distance. These results suggest how mechanics plays a role in cardiac efficiency, and may be relevant for the design of cardiomyocyte based micro devices and other biomedical applications.

  11. Transcriptional Effects of E3 Ligase Atrogin-1/MAFbx on Apoptosis, Hypertrophy and Inflammation in Neonatal Rat Cardiomyocytes

    PubMed Central

    Zeng, Yong; Wang, Hong-Xia; Guo, Shu-Bin; Yang, Hui; Zeng, Xiang-Jun; Fang, Quan; Tang, Chao-Shu; Du, Jie; Li, Hui-Hua

    2013-01-01

    Atrogin-1/MAFbx is an ubiquitin E3 ligase that regulates myocardial structure and function through the ubiquitin-dependent protein modification. However, little is known about the effect of atrogin-1 activation on the gene expression changes in cardiomyocytes. Neonatal rat cardiomyocytes were infected with adenovirus atrogin-1 (Ad-atrogin-1) or GFP control (Ad-GFP) for 24 hours. The gene expression profiles were compared with microarray analysis. 314 genes were identified as differentially expressed by overexpression of atrogin-1, of which 222 were up-regulated and 92 were down-regulated. Atrogin-1 overexpression significantly modulated the expression of genes in 30 main functional categories, most genes clustered around the regulation of cell death, proliferation, inflammation, metabolism and cardiomyoctye structure and function. Moreover, overexpression of atrogin-1 significantly inhibited cardiomyocyte survival, hypertrophy and inflammation under basal condition or in response to lipopolysaccharide (LPS). In contrast, knockdown of atrogin-1 by siRNA had opposite effects. The mechanisms underlying these effects were associated with inhibition of MAPK (ERK1/2, JNK1/2 and p38) and NF-κB signaling pathways. In conclusion, the present microarray analysis reveals previously unappreciated atrogin-1 regulation of genes that could contribute to the effects of atrogin-1 on cardiomyocyte survival, hypertrophy and inflammation in response to endotoxin, and may provide novel insight into how atrogin-1 modulates the programming of cardiac muscle gene expression. PMID:23335977

  12. Implications of Stem Cell Growth Regulation for Breast Cancer

    DTIC Science & Technology

    2007-06-01

    during development and maintenance of the gland could determine the growth potential, differentiation and senescence of the mammary epithelial cell...described the fractions of mature and stem/progenitor cells in developing and adult mammary gland, that took into account well-understood biological...aging and senescence of the mammary population. Mice with a null mutation in syndecan-1 (Sdc1) resist tumor development in a number of different

  13. Androgen receptor signaling regulates growth of glioblastoma multiforme in men.

    PubMed

    Yu, Xiaoming; Jiang, Yuhua; Wei, Wei; Cong, Ping; Ding, Yinlu; Xiang, Lei; Wu, Kang

    2015-02-01

    Although glioblastoma multiforme (GBM) is the most malignant primary human brain cancer with surprisingly high incidence rate in adult men than in women, the exact mechanism underlying this pronounced epidemiology is unclear. Here, we showed significant upregulated androgen receptor (AR) expression in the GBM tissue compared to the periphery normal brain tissue in patients. An expression of AR was further detected in all eight examined human GBM cell lines. To figure out whether AR signaling may play a role in GBM, we used high AR-expressing U87-MG GBM line for further study. We found that activation of transforming growth factor β (TGFβ) receptor signaling by TGFβ1 in GBM significantly inhibited cell growth and increased apoptosis. Moreover, application of active AR ligand 5α-dihydrotestosterone (DHT) significantly decreased the effect of TGFβ1 on GBM growth and apoptosis, suggesting that AR signaling pathway may contradict the effect of TGFβ receptor signaling in GBM. However, neither total protein nor the phosphorylated protein of SMAD3, a major TGFβ receptor signaling downstream effector in GBM, was affected by DHT, suggesting that AR activation may not affect the SMAD3 protein production or phosphorylation of TGFβ receptor and SMAD3. Finally, immunoprecipitation followed by immunoblot confirmed binding of pAR to pSMAD3, which may prevent the DNA binding of pSMAD3 and subsequently prevent its effect on cell growth in GBM. Taken together, our study suggests that AR signaling may promote tumorigenesis of GBM in adult men by inhibiting TGFβ receptor signaling.

  14. Cardiomyocyte death in doxorubicin-induced cardiotoxicity

    PubMed Central

    Zhang, Yi-Wei; Shi, Jianjian; Li, Yuan-Jian; Wei, Lei

    2009-01-01

    SUMMARY Doxorubicin (DOX) is one of the most widely used and successful antitumor drugs, but its cumulative and dose-dependent cardiac toxicity has been the major concern of oncologists in cancer therapeutic practice for decades. With the increasing population of cancer survivals, there is a growing need to develop preventive strategies and effective therapies against DOX-induced cardiotoxicity, in particular, the late onset cardiomyopathy. Although intensive investigations on the DOX-induced cardiotoxicity have been continued for decades, the underlying mechanisms responsible for DOX-induced cardiotoxicity have not been completely elucidated. A rapidly expanding body of evidence supports that cardiomyocyte death by apoptosis and necrosis is a primary mechanism of DOX-induced cardiomyopathy and other types of cell death, such as autophagy and senescence/aging, may participate in this process. In this review, we will focus on the current understanding of molecular mechanisms underlying DOX-induced cardiomyocyte death, including the major primary mechanism of excess production of reactive oxygen species (ROS) and other recently discovered ROS-independent mechanisms. Different sensitivity to DOX-induced cell death signals between adult and young cardiomyocytes will also be discussed. PMID:19866340

  15. Ca²⁺ signal-induced cardiomyocyte hypertrophy through activation of myocardin.

    PubMed

    Li, Man; Wang, Nan; Gong, Hui-Qin; Li, Wei-Zong; Liao, Xing-Hua; Yang, Xiao-Long; He, Hong-Peng; Cao, Dong-Sun; Zhang, Tong-Cun

    2015-02-15

    Hypertrophic growth of cardiomyocytes in response to pressure overload is an important stage during the development of many cardiac diseases. Ca(2+) overload as well as subsequent activation of Ca(2+) signaling pathways has been reported to induce cardiac hypertrophy. Myocardin, a transcription cofactor of serum response factor (SRF), is a key transducer of hypertrophic signals. However, the direct role of myocardin in Ca(2+) signal-induced cardiomyocyte hypertrophy has not been explained clearly. In the present study, we discovered that embryonic rat heart-derived H9c2 cells responded to the stimulation of calcium ionophore A23187 with a cell surface area enlargement and an increased expression of cardiac hypertrophy marker genes. Increased Ca(2+) also induces an organization of sarcomeres in neonatal rat cardiomyocytes, as revealed by α-actinin staining. Increased Ca(2+) could upregulate the expression of myocardin. Knockdown of myocardin by shRNA attenuates hypertrophic responses triggered by increased intracellular Ca(2+), suggesting that Ca(2+) signals induce cardiomyocyte hypertrophy partly through activation of myocardin. Furthermore, A23187 treatment directly activates myocardin promoter, chelation of Ca(2+) by EGTA inhibits this activation and knockdown of myocardin expression using shRNA also abrogates A23187-induced ANF and SK-α-actin promoter activity. CSA (calcineurin inhibitor) and KN93 (CaMKII inhibitor) inhibit A23187-induced the increase in myocardin expression. These results suggest that myocardin plays a critical role in Ca(2+) signal-induced cardiomyocyte hypertrophy, which may serve as a novel mechanism that is important for cardiac hypertrophy.

  16. Targeted deletion of Tsc1 causes fatal cardiomyocyte hyperplasia independently of afterload.

    PubMed

    Kayyali, Usamah S; Larsen, Christopher G; Bashiruddin, Sarah; Lewandowski, Sara L; Trivedi, Chinmay M; Warburton, Rod R; Parkhitko, Andrey A; Morrison, Tasha A; Henske, Elizabeth P; Chekaluk, Yvonne; Kwiatkowski, David J; Finlay, Geraldine A

    2015-01-01

    Despite high expression levels, the role of Tsc1 in cardiovascular tissue is ill defined. We launched this study to examine the role of Tsc1 in cardiac physiology and pathology. Mice in which Tsc1 was deleted in cardiac tissue and vascular smooth muscle (Tsc1c/cSM22cre(+/-)), developed progressive cardiomegaly and hypertension and died early. Hearts of Tsc1c/cSM22cre(+/-) mice displayed a progressive increase in cardiomyocyte number, and to a lesser extent, size between the ages of 1 and 6 weeks. In addition, compared to control hearts, proliferation markers (phospho-histone 3 and PCNA) were elevated in Tsc1c/cSM22cre(+/-) cardiomyocytes at 0-4 weeks, suggesting that cardiomyocyte proliferation was the predominant mechanism underlying cardiomegaly in Tsc1c/cSM22cre(+/-) mice. To examine the contribution of Tsc1 deletion in peripheral vascular smooth muscle to the cardiac phenotype, Tsc1c/cSM22cre(+/-) mice were treated with the antihypertensive, hydralazine. Prevention of hypertension had no effect on survival, cardiac size, or cardiomyocyte number in these mice. We furthermore generated mice in which Tsc1 was deleted only in vascular smooth muscle but not in cardiac tissue (Tsc1c/cSMAcre-ER(T2+/-)). The Tsc1c/cSMAcre-ER(T2+/-) mice also developed hypertension. However, their survival was normal and no cardiac abnormalities were observed. Our results suggest that loss of Tsc1 in the heart causes cardiomegaly, which is driven by increased cardiomyocyte proliferation that also appears to confer relative resistance to afterload reduction. These findings support a critical role for the Tsc1 gene as gatekeeper in the protection against uncontrolled cardiac growth.

  17. Polyamines regulate cell growth and cellular methylglyoxal in high-glucose medium independently of intracellular glutathione.

    PubMed

    Kwak, Min-Kyu; Lee, Mun-Hyoung; Park, Seong-Jun; Shin, Sang-Min; Liu, Rui; Kang, Sa-Ouk

    2016-03-01

    Polyamines can presumably inhibit protein glycation, when associated with the methylglyoxal inevitably produced during glycolysis. Herein, we hypothesized a nonenzymatic interaction between putrescine and methylglyoxal in putrescine-deficient or -overexpressing Dictyostelium cells in high-glucose medium, which can control methylglyoxal production. Putrescine was essentially required for growth rescue accompanying methylglyoxal detoxification when cells underwent growth defect and cell cycle G1-arrest when supplemented with high glucose. Furthermore, methylglyoxal regulation by putrescine seemed to be a parallel pathway independent of the changes in cellular glutathione content in high-glucose medium. Consequently, we suggest that Dictyostelium cells need polyamines for normal growth and cellular methylglyoxal regulation.

  18. Regulation of Long Bone Growth in Vertebrates; It Is Time to Catch Up.

    PubMed

    Roselló-Díez, Alberto; Joyner, Alexandra L

    2015-12-01

    The regulation of organ size is essential to human health and has fascinated biologists for centuries. Key to the growth process is the ability of most organs to integrate organ-extrinsic cues (eg, nutritional status, inflammatory processes) with organ-intrinsic information (eg, genetic programs, local signals) into a growth response that adapts to changing environmental conditions and ensures that the size of an organ is coordinated with the rest of the body. Paired organs such as the vertebrate limbs and the long bones within them are excellent models for studying this type of regulation because it is possible to manipulate one member of the pair and leave the other as an internal control. During development, growth plates at the end of each long bone produce a transient cartilage model that is progressively replaced by bone. Here, we review how proliferation and differentiation of cells within each growth plate are tightly controlled mainly by growth plate-intrinsic mechanisms that are additionally modulated by extrinsic signals. We also discuss the involvement of several signaling hubs in the integration and modulation of growth-related signals and how they could confer remarkable plasticity to the growth plate. Indeed, long bones have a significant ability for "catch-up growth" to attain normal size after a transient growth delay. We propose that the characterization of catch-up growth, in light of recent advances in physiology and cell biology, will provide long sought clues into the molecular mechanisms that underlie organ growth regulation. Importantly, catch-up growth early in life is commonly associated with metabolic disorders in adulthood, and this association is not completely understood. Further elucidation of the molecules and cellular interactions that influence organ size coordination should allow development of novel therapies for human growth disorders that are noninvasive and have minimal side effects.

  19. NPR3 protects cardiomyocytes from apoptosis through inhibition of cytosolic BRCA1 and TNF-α

    PubMed Central

    Lin, Dong; Chai, Yubo; Izadpanah, Reza; Braun, Stephen E.; Alt, Eckhard

    2016-01-01

    ABSTRACT Natriuretic peptide receptor 3 (NPR3) is a clearance receptor by binding and internalizing natriuretic peptides (NPs) for ultimate degradation. Patients with cardiac failure show elevated NPs. NPs are linked to poor long-term survival because of their apoptotic effects. However, the underling mechanisms have not been identified yet. Here we report the role of NPR3 in anti-apoptosis via the breast cancer type 1 susceptibility protein (BRCA1) and tumor necrosis factor α (TNF-α ). To demonstrate a role for NPR3 in apoptosis, stable H9C2 cardiomyocyte cell lines using shRNA to knockdown NPR3 were generated. The activities of caspase-3, 8, and 9 were significantly increased in NPR3 knockdown H9C2 cardiomyocytes. Knockdown of NPR3 increased the expression of BRCA1. Also NPR3 knockdown remarkably increased the activity of cAMP response element-binding protein (CREB), a positive regulatory element for BRCA1 expression. BRCA1 showed dispersed nuclear localization in non-cardiomyocytes while predominantly cytoplasmic localization in H9C2 cells. Meanwhile, NPR3 knockdown significantly increased TNF-α gene expression. These data show that NPR3 knockdown in H9C2 cells triggered both extrinsic and intrinsic apoptotic pathways. NPR3 protects cardiomyocytes from apoptosis through inhibition of cytosolic BRCA1 and TNF-α, which are regulators of apoptosis. Our studies demonstrate anti-apoptosis role of NPR3 in protecting cardiomyocytes and establish the first molecular link between NP system and programmed cell death. PMID:27494651

  20. The impact of caffeine on connexin expression in the embryonic chick cardiomyocyte micromass culture system.

    PubMed

    Ahir, Bhavesh K; Pratten, Margaret K

    2016-07-01

    Cardiomyocytes are electrically coupled by gap junctions, defined as clusters of low-resistance multisubunit transmembrane channels composed of connexins (Cxs). The expression of Cx40, Cx43 and Cx45, which are present in cardiomyocytes, is known to be developmentally regulated. This study investigates the premise that alterations in gap junction proteins are one of the mechanisms by which teratogens may act. Specifically, those molecules known to be teratogenic in humans could cause their effects via disruption of cell-to-cell communication pathways, resulting in an inability to co-ordinate tissue development. Caffeine significantly inhibited contractile activity at concentrations above and including 1500 μm (P < 0.05), while not affecting cell viability and total protein, in the embryonic chick cardiomyocyte micromass culture system. The effects of caffeine on key cardiac gap junction protein (Cx40, Cx43 and Cx45) expression were analysed using immunocytochemistry and in-cell Western blotting. The results indicated that caffeine altered the expression pattern of Cx40, Cx43 and Cx45 at non-cytotoxic concentrations (≥2000 μm), i.e., at concentrations that did not affect total cell protein and cell viability. In addition the effects of caffeine on cardiomyocyte formation and function (contractile activity score) were correlated with modulation of Cxs (Cx40, Cx43 and Cx45) expression, at above and including 2000 μm caffeine concentrations (P < 0.05). These experiments provide evidence that embryonic chick cardiomyocyte micromass culture may be a useful in vitro method for mechanistic studies of perturbation of embryonic heart development. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Panax quinquefolium saponin attenuates cardiomyocyte apoptosis induced by thapsigargin through inhibition of endoplasmic reticulum stress

    PubMed Central

    Liu, Mi; Xue, Mei; Wang, Xiao-Reng; Tao, Tian-Qi; Xu, Fei-Fei; Liu, Xiu-Hua; Shi, Da-Zhuo

    2015-01-01

    Background Endoplasmic reticulum (ER) stress-related apoptosis is involved in the pathophysiology of many cardiovascular diseases, and Panax quinquefolium saponin (PQS) is able to inhibit excessive ER stress-related apoptosis of cardiomyocytes following hypoxia/reoxygenation and myocardial infarction. However, the pathway by which PQS inhibits the ER stress-related apoptosis is not well understood. To further investigate the protective effect of PQS against ER stress-related apoptosis, primary cultured cardiomyocytes were stimulated with thapsigargin (TG), which is widely used to model cellular ER stress, and it could induce apoptotic cell death in sufficient concentration. Methods Primary cultured cardiomyocytes from neonatal rats were exposed to TG (1 µmol/L) treatment for 24 h, following PQS pre-treatment (160 µg/mL) for 24 h or pre-treatment with small interfering RNA directed against protein kinase-like endoplasmic reticulum kinase (Si-PERK) for 6 h. The viability and apoptosis rate of cardiomyocytes were detected by cell counting kit-8 and flow cytometry respectively. ER stress-related protein expression, such as glucose-regulated protein 78 (GRP78), calreticulin, PERK, eukaryotic translation initiation factor 2α (eIF2α), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP) were assayed by western blotting. Results Both PQS pre-treatment and PERK knockdown remarkably inhibited the cardiomyocyte apoptosis induced by TG, increased cell viability, decreased phosphorylation of both PERK and eIF2α, and decreased protein levels of both ATF4 and CHOP. There was no statistically significant difference between PQS pre-treatment and PERK knockdown in the cardioprotective effect. Conclusions Our data indicate that the PERK-eIF2α-ATF4-CHOP pathway of ER stress is involved in the apoptosis induced by TG, and PQS might prevent TG-induced cardiomyocyte apoptosis through a mechanism involving the suppression of this pathway. These findings

  2. Follicular growth and atresia in mammalian ovaries: regulation by survival and death of granulosa cells.

    PubMed

    Matsuda, Fuko; Inoue, Naoko; Manabe, Noboru; Ohkura, Satoshi

    2012-01-01

    The mammalian ovary is an extremely dynamic organ in which a large majority of follicles are effectively eliminated throughout their reproductive life. Due to the numerous efforts of researchers, mechanisms regulating follicular growth and atresia in mammalian ovaries have been clarified, not only their systemic regulation by hormones (gonadotropins) but also their intraovarian regulation by gonadal steroids, growth factors, cytokines and intracellular proteins. Granulosa cells in particular have been demonstrated to play a major role in deciding the fate of follicles, serving molecules that are essential for follicular growth and maintenance as well as killing themselves by an apoptotic process that results in follicular atresia. In this review, we discuss the factors that govern follicular growth and atresia, with a special focus on their regulation by granulosa cells. First, ovarian folliculogenesis in adult life is outlined. Then, we explain about the regulation of follicular growth and atresia by granulosa cells, in which hormones, growth factors and cytokines, death ligand-receptor system and B cell lymphoma/leukemia 2 (BCL2) family members (mitochondria-mediated apoptosis) are further discussed.

  3. Root growth regulation and gravitropism in maize roots does not require the epidermis

    NASA Technical Reports Server (NTRS)

    Bjorkman, T.; Cleland, R. E.

    1991-01-01

    We have earlier published observations showing that endogenous alterations in growth rate during gravitropism in maize roots (Zea mays L.) are unaffected by the orientation of cuts which remove epidermal and cortical tissue in the growing zone (Bjorkman and Cleland, 1988, Planta 176, 513-518). We concluded that the epidermis and cortex are not essential for transporting a growth-regulating signal in gravitropism or straight growth, nor for regulating the rate of tissue expansion. This conclusion has been challenged by Yang et al. (1990, Planta 180, 530-536), who contend that a shallow girdle around the entire perimeter of the root blocks gravitropic curvature and that this inhibition is the result of a requirement for epidermal cells to transport the growth-regulating signal. In this paper we demonstrate that the entire epidermis can be removed without blocking gravitropic curvature and show that the position of narrow girdles does not affect the location of curvature. We therefore conclude that the epidermis is not required for transport of a growth-regulating substance from the root cap to the growing zone, nor does it regulate the growth rate of the elongating zone of roots.

  4. Modulation of cardiomyocyte activity using pulsed laser irradiated gold nanoparticles

    PubMed Central

    Gentemann, Lara; Kalies, Stefan; Coffee, Michelle; Meyer, Heiko; Ripken, Tammo; Heisterkamp, Alexander; Zweigerdt, Robert; Heinemann, Dag

    2016-01-01

    Can photothermal gold nanoparticle mediated laser manipulation be applied to induce cardiac contraction? Based on our previous work, we present a novel concept of cell stimulation. A 532 nm picosecond laser was employed to heat gold nanoparticles on cardiomyocytes. This leads to calcium oscillations in the HL-1 cardiomyocyte cell line. As calcium is connected to the contractility, we aimed to alter the contraction rate of native and stem cell derived cardiomyocytes. A contraction rate increase was particularly observed in calcium containing buffer with neonatal rat cardiomyocytes. Consequently, the study provides conceptual ideas for a light based, nanoparticle mediated stimulation system. PMID:28101410

  5. Stimulation of cardiomyocyte regeneration in neonatal mice and in human myocardium with neuregulin reveals a therapeutic window

    PubMed Central

    Polizzotti, Brian D.; Ganapathy, Balakrishnan; Walsh, Stuart; Choudhury, Sangita; Ammanamanchi, Niyatie; Bennett, David G.; dos Remedios, Cristobal G.; Haubner, Bernhard J.; Penninger, Josef M.; Kuhn, Bernhard

    2015-01-01

    Background Pediatric patients with heart failure are treated with medical therapies that were developed for adult patients. These therapies have been shown to be ineffective in pediatric trials, leading to the recognition that new pediatric-specific therapies must be developed. We have previously shown that administration of the recombinant growth factor neuregulin-1 (rNRG1) stimulates heart muscle cell (cardiomyocyte) regeneration in adult mice. We hypothesized that rNRG1 administration may be more effective in the neonatal period, which could provide a new therapeutic paradigm for treating heart failure in pediatric patients. Methods We used a cryoinjury model to induce myocardial dysfunction and scar formation for evaluating the effectiveness of rNRG1-administration in neonatal mice. We evaluated the ability of rNRG1 to stimulate cardiomyocyte proliferation in intact cultured myocardium from pediatric patients. Results After cryoinjury in neonatal mice, early administration of rNRG1 from birth for 34 days improved myocardial function and reduced the prevalence of transmural scars. In contrast, late administration of rNRG1 from 4 to 34 days after cryoinjury transiently improved myocardial function. The mechanisms of early administration involved cardiomyocyte protection (38%) and proliferation (62%). rNRG1 induced cardiomyocyte proliferation in myocardium from infants with heart disease less than 6 months of age. Conclusion Our results identify a more effective time period within which to execute future clinical trials of rNRG1 for stimulating cardiomyocyte regeneration. PMID:25834111

  6. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters.

    PubMed

    Ramesh, Sunita A; Tyerman, Stephen D; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A; Ryan, Peter R; Gilliham, Matthew; Gillham, Matthew

    2015-07-29

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms.

  7. Early growth response 3 (Egr-3) is induced by transforming growth factor-β and regulates fibrogenic responses.

    PubMed

    Fang, Feng; Shangguan, Anna J; Kelly, Kathleen; Wei, Jun; Gruner, Katherine; Ye, Boping; Wang, Wenxia; Bhattacharyya, Swati; Hinchcliff, Monique E; Tourtellotte, Warren G; Varga, John

    2013-10-01

    Members of the early growth response (Egr) gene family of transcription factors have nonredundant biological functions. Although Egr-3 is implicated primarily in neuromuscular development and immunity, its regulation and role in tissue repair and fibrosis has not been studied. We now show that in normal skin fibroblasts, Egr-3 was potently induced by transforming growth factor-β via canonical Smad3. Moreover, transient Egr-3 overexpression was sufficient to stimulate fibrotic gene expression, whereas deletion of Egr-3 resulted in substantially attenuated transforming growth factor-β responses. Genome-wide expression profiling in fibroblasts showed that genes associated with tissue remodeling and wound healing were prominently up-regulated by Egr-3. Notably, <5% of fibroblast genes regulated by Egr-1 or Egr-2 were found to be coregulated by Egr-3, revealing substantial functional divergence among these Egr family members. In a mouse model of scleroderma, development of dermal fibrosis was accompanied by accumulation of Egr-3-positive myofibroblasts in the lesional tissue. Moreover, skin biopsy samples from patients with scleroderma showed elevated Egr-3 levels in the dermis, and Egr-3 mRNA levels correlated with the extent of skin involvement. These results provide the first evidence that Egr-3, a functionally distinct member of the Egr family with potent effects on inflammation and immunity, is up-regulated in scleroderma and is necessary and sufficient for profibrotic responses, suggesting important and distinct roles in the pathogenesis of fibrosis.

  8. Organ-specific regulation of growth-defense tradeoffs by plants.

    PubMed

    Smakowska, Elwira; Kong, Jixiang; Busch, Wolfgang; Belkhadir, Youssef

    2016-02-01

    Plants grow while also defending themselves against phylogenetically unrelated pathogens. Because defense and growth are both costly programs, a plant's success in colonizing resource-scarce environments requires tradeoffs between the two. Here, we summarize efforts aimed at understanding how plants use iterative tradeoffs to modulate differential organ growth when defenses are elicited. First, we focus on shoots to illustrate how light, in conjunction with the growth hormone gibberellin (GA) and the defense hormone jasmonic acid (JA), act to finely regulate defense and growth programs in this organ. Second, we expand on the regulation of growth-defense trade-offs in the root, a less well-studied topic despite the critical role of this organ in acquiring resources in an environment deeply entrenched with disparate populations of microbes.

  9. New findings in the mechanisms regulating polar growth in root hair cells.

    PubMed

    Cárdenas, Luis

    2009-01-01

    Root hairs cells are highly polarized cellular structures resulting from tip growth of specific root epidermal cells. Root-hair morphogenesis involves many aspects regulating tip growth such as exocytosis, ion flux, calcium homeostasis, reactive oxygen species (ROS), and cytoskeleton. These cells are excellent models for studying polar growth and can be challenged with many extracellular factors affecting the pattern of growth named Nod factors, elicitors, hormones, etc. The general scenery is that the well described tip-high intracellular Ca(2+) gradient plays a central role in regulating tip growth. On the other hand, ROS plays a key role in various processes, for example hypersensitive response, root hair development, hormone action, gravitropism and stress responses. However, ROS has recently emerged as a key player together with calcium in regulating polar growth, not only in root hair cells but also in pollen tubes, filamentous fungi and fucoid cells. Furthermore, Ca(2+)-permeable channel modulation by ROS has been demonstrated in Vicia faba guard cells and Arabidopsis root hairs. Recently, root hair cells were shown to experiment ROS, pH and calcium oscillations coupled to growth oscillation. These recent findings allow considering that root hair cells present a similar pattern of growth as described for pollen tubes.

  10. Regulation of Long Bone Growth in Vertebrates; It Is Time to Catch Up

    PubMed Central

    Joyner, Alexandra L.

    2015-01-01

    The regulation of organ size is essential to human health and has fascinated biologists for centuries. Key to the growth process is the ability of most organs to integrate organ-extrinsic cues (eg, nutritional status, inflammatory processes) with organ-intrinsic information (eg, genetic programs, local signals) into a growth response that adapts to changing environmental conditions and ensures that the size of an organ is coordinated with the rest of the body. Paired organs such as the vertebrate limbs and the long bones within them are excellent models for studying this type of regulation because it is possible to manipulate one member of the pair and leave the other as an internal control. During development, growth plates at the end of each long bone produce a transient cartilage model that is progressively replaced by bone. Here, we review how proliferation and differentiation of cells within each growth plate are tightly controlled mainly by growth plate-intrinsic mechanisms that are additionally modulated by extrinsic signals. We also discuss the involvement of several signaling hubs in the integration and modulation of growth-related signals and how they could confer remarkable plasticity to the growth plate. Indeed, long bones have a significant ability for “catch-up growth” to attain normal size after a transient growth delay. We propose that the characterization of catch-up growth, in light of recent advances in physiology and cell biology, will provide long sought clues into the molecular mechanisms that underlie organ growth regulation. Importantly, catch-up growth early in life is commonly associated with metabolic disorders in adulthood, and this association is not completely understood. Further elucidation of the molecules and cellular interactions that influence organ size coordination should allow development of novel therapies for human growth disorders that are noninvasive and have minimal side effects. PMID:26485225

  11. Glucocorticoids and the regulation of growth hormone secretion.

    PubMed

    Mazziotti, Gherardo; Giustina, Andrea

    2013-05-01

    Glucocorticoids modulate the secretion of growth hormone (GH) by various and competing effects on the hypothalamus and pituitary gland. The final effects of this modulation depend on hormone concentrations and the duration of exposure. The traditional hypothesis is that chronically raised levels of glucocorticoids suppress the secretion of GH. However, a functional impairment of the GH reserve might also be observed in patients with low levels of glucocorticoids, such as those with secondary hypoadrenalism, which is consistent with the model of biphasic dose-dependent effects of glucocorticoids on the somatotropic axis. This Review updates our current understanding of the mechanisms underlying the effects of glucocorticoids on the secretion of GH and the clinical implications of the dual action of glucocorticoids on the GH reserve in humans. This Review will also address the potential diagnostic and therapeutic implications of GH for patients with a deficiency or excess of glucocorticoids.

  12. Androgen regulation of axon growth and neurite extension in motoneurons

    PubMed Central

    Fargo, Keith N.; Galbiati, Mariarita; Foecking, Eileen M.; Poletti, Angelo; Jones, Kathryn J.

    2008-01-01

    Androgens act on the CNS to affect motor function through interaction with a widespread distribution of intracellular androgen receptors (AR). This review highlights our work on androgens and process outgrowth in motoneurons, both in vitro and in vivo. The actions of androgens on motoneurons involve the generation of novel neuronal interactions that are mediated by the induction of androgen-dependent neurite or axonal outgrowth. Here, we summarize the experimental evidence for the androgenic regulation of the extension and regeneration of motoneuron neurites in vitro using cultured immortalized motoneurons, and axons in vivo using the hamster facial nerve crush paradigm. We place particular emphasis on the relevance of these effects to SBMA and peripheral nerve injuries. PMID:18387610

  13. Nervous Wreck and Cdc42 cooperate to regulate endocytic actin assembly during synaptic growth

    PubMed Central

    Rodal, Avital A.; Motola-Barnes, Rebecca N.; Littleton, J. Troy

    2008-01-01

    Regulation of synaptic morphology depends on endocytosis of activated growth signal receptors, but the mechanisms regulating this membrane trafficking event are unclear. Actin polymerization mediated by WASp (Wiskott-Aldrich Syndrome Protein) and the Arp2/3 (Actin related protein 2/3) complex generates forces at multiple stages of endocytosis. F-BAR/SH3 domain proteins play key roles in this process by coordinating membrane deformation with WASp-dependent actin polymerization. However, it is not known how other WASp ligands, such as the small GTPase Cdc42, coordinate with F-BAR/SH3 proteins to regulate actin polymerization at membranes. Nervous Wreck (Nwk) is a conserved neuronal F-BAR/SH3 protein that localizes to periactive zones at the Drosophila larval neuromuscular junction (NMJ) and is required for regulation of synaptic growth via BMP signaling. Here we show that Nwk interacts with the endocytic proteins dynamin and Dap160 and functions together with Cdc42 to promote WASp-mediated actin polymerization in vitro and to regulate synaptic growth in vivo. Cdc42 function is associated with Rab11-dependent recycling endosomes, and we show that Rab11 co-localizes with Nwk at the NMJ. Taken together, our results suggest that synaptic growth activated by growth factor signaling is controlled at an endosomal compartment via coordinated Nwk and Cdc42-dependent actin assembly. PMID:18701694

  14. Spontaneously beating cardiomyocytes derived from white mature adipocytes

    PubMed Central

    Jumabay, Medet; Zhang, Rui; Yao, Yucheng; Goldhaber, Joshua I.; Boström, Kristina I.

    2010-01-01

    Aims Adipose stromal cells and dissociated brown adipose tissue have been shown to generate cardiomyocyte-like cells. However, it is not clear whether white mature adipocytes have the same potential, even though a close relationship has been found between adipocytes and vascular endothelial cells, another cardiovascular cell type. The objective of this study was to examine if white adipocytes would be able to supply cardiomyocytes. Methods and results We prepared a highly purified population of lipid-filled adipocytes from mice, 6–7 weeks of age. When allowed to lose lipids, the adipocytes assumed a fibroblast-like morphology, so-called dedifferentiated fat (DFAT) cells. Subsequently, 10–15% of the DFAT cells spontaneously differentiated into cardiomyocyte-like cells, in which the cardiomyocyte phenotype was identified by morphological observations, expression of cardiomyocyte-specific markers, and immunocytochemical staining. In addition, electrophysiological studies revealed pacemaker activity in these cells, and functional studies showed that a β-adrenergic agonist stimulated the beating rate, whereas a β-antagonist reduced it. In vitro treatment of newly isolated adipocytes or DFAT cells with inhibitors of bone morphogenetic proteins (BMP) and Wnt signalling promoted the development of the cardiomyocyte phenotype as determined by the number or beating colonies of cardiomyocyte-like cells and expression of troponin I, a cardiomyocyte-specific marker. Inhibition of BMP was most effective in promoting the cardiomyocyte phenotype in adipocytes, whereas Wnt-inhibition was most effective in DFAT cells. Conclusion White mature adipocytes can differentiate into cardiomyocyte-like cells, suggesting a link between adipocyte and cardiomyocyte differentiation. PMID:19643806

  15. Long- and short-distance signaling in the regulation of lateral plant growth.

    PubMed

    Brackmann, Klaus; Greb, Thomas

    2014-06-01

    Lateral growth of shoot and root axes by the formation of secondary vascular tissues is an instructive example for the plasticity of plant growth processes. Being purely postembryonic, lateral growth strongly depends on environmental input and is tightly regulated by long- and short-distance signaling. In general, plant vasculature represents the main route for long-distance transport of compounds throughout the plant body, thereby providing also a fast and efficient signaling pipeline for the coordination of growth and development. The vasculature consists of three major tissues; the xylem conducts water and nutrients, the phloem transports mainly organic compounds and the vascular cambium is a group of undifferentiated stem cells responsible for the continuous production of secondary vascular tissues. Notably, the close proximity to functional vascular tissues makes the vascular cambium especially accessible for the regulation by long-distance-derived signaling molecules as well as by the physical and physiological properties of transport streams. Thus, the vascular cambium offers unique opportunities for studying the complex regulation of plant growth processes. In this review, we focus on recent findings about long- and short-distance signaling mechanisms regulating cambium activity and, thereby, lateral expansion of plant growth axes by the formation of additional vascular tissues.

  16. ABA Suppresses Root Hair Growth via the OBP4 Transcriptional Regulator1[OPEN

    PubMed Central

    Kawamura, Ayako; Schäfer, Sabine; Breuer, Christian; Shibata, Michitaro; Mitsuda, Nobutaka; Ohme-Takagi, Masaru; Matsui, Minami

    2017-01-01

    Plants modify organ growth and tune morphogenesis in response to various endogenous and environmental cues. At the cellular level, organ growth is often adjusted by alterations in cell growth, but the molecular mechanisms underlying this control remain poorly understood. In this study, we identify the DNA BINDING WITH ONE FINGER (DOF)-type transcription regulator OBF BINDING PROTEIN4 (OBP4) as a repressor of cell growth. Ectopic expression of OBP4 in Arabidopsis (Arabidopsis thaliana) inhibits cell growth, resulting in severe dwarfism and the repression of genes involved in the regulation of water transport, root hair development, and stress responses. Among the basic helix-loop-helix transcription factors known to control root hair growth, OBP4 binds the ROOT HAIR DEFECTIVE6-LIKE2 (RSL2) promoter to repress its expression. The accumulation of OBP4 proteins is detected in expanding root epidermal cells, and its expression level is increased by the application of abscisic acid (ABA) at concentrations sufficient to inhibit root hair growth. ABA-dependent induction of OBP4 is associated with the reduced expression of RSL2. Furthermore, ectopic expression of OBP4 or loss of RSL2 function results in ABA-insensitive root hair growth. Taken together, our results suggest that OBP4-mediated transcriptional repression of RSL2 contributes to the ABA-dependent inhibition of root hair growth in Arabidopsis. PMID:28167701

  17. Regulating continent growth and composition by chemical weathering

    USGS Publications Warehouse

    Lee, C.-T.A.; Morton, D.M.; Little, M.G.; Kistler, R.; Horodyskyj, U.N.; Leeman, W.P.; Agranier, A.

    2008-01-01

    Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. ?? 2008 by The National Academy of Sciences of the USA.

  18. Host metabolism regulates growth and differentiation of Toxoplasma gondii

    PubMed Central

    Weilhammer, Dina R.; Iavarone, Anthony T.; Villegas, Eric N.; Brooks, George A.; Sinai, Anthony P.; Sha, William C.

    2012-01-01

    A critical step in the pathogenesis of Toxoplasma gondii is conversion from the fast-replicating tachyzoite form experienced during acute infection to the slow-replicating bradyzoite form that establishes long-lived tissue cysts during chronic infection. Bradyzoite cyst development exhibits a clear tissue tropism in vivo, yet conditions of the host cell environment that influence this tropism remain unclear. Using an in vitro assay of bradyzoite conversion, we have found that cell types differ dramatically in the ability to facilitate differentiation of tachyzoites into bradyzoites. Characterization of cell types that were either resistant or permissive for conversion revealed that resistant cell lines release low molecular weight metabolites that could support tachyzoite growth under metabolic stress conditions and thereby inhibit bradyzoite formation in permissive cells. Biochemical analysis revealed that the glycolytic metabolite lactate is an inhibitory component of supernatants from resistant cells. Furthermore, upregulation of glycolysis in permissive cells through the addition of glucose or by overexpression of the host kinase, Akt, was sufficient to convert cells from a permissive to a resistant phenotype. These results suggest that the metabolic state of the host cell may play a role in determining the predilection of the parasite to switch from the tachyzoite to bradyzoite form. PMID:22940576

  19. Regulating continent growth and composition by chemical weathering

    PubMed Central

    Lee, Cin-Ty Aeolus; Morton, Douglas M.; Little, Mark G.; Kistler, Ronald; Horodyskyj, Ulyana N.; Leeman, William P.; Agranier, Arnaud

    2008-01-01

    Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. PMID:18362343

  20. Regulating continent growth and composition by chemical weathering.

    PubMed

    Lee, Cin-Ty Aeolus; Morton, Douglas M; Little, Mark G; Kistler, Ronald; Horodyskyj, Ulyana N; Leeman, William P; Agranier, Arnaud

    2008-04-01

    Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms.

  1. Coordinated regulation of growth genes in Saccharomyces cerevisiae.

    PubMed

    Slattery, Matthew G; Heideman, Warren

    2007-05-15

    It is imperative that quiescent Saccharomyces cerevisiae cells respond rapidly to fresh medium: the cell that initiates growth and division soonest has the most progeny. Several laboratories have used DNA microarrays to identify transcripts that are altered when fresh medium is added to quiescent cells. We combined published data with our own to address several questions: Do these experiments taken together identify a core set of genes that is reproducibly affected when quiescent cells are stimulated by nutrient repletion? Is this gene set coregulated in response to other environmental challenges? Does promoter histone occupancy correlate with the mRNA data? Despite diverse experimental designs, the data were highly correlated, generating a set of nutrient repletion transcripts. Glucose addition accounted for the response. These transcripts were also coregulated in response to diverse stresses. Promoters were associated with increased histone acetylation and decreased histone occupancy when induced, and high histone occupancy with low acetylation when repressed. The presence of RRPE and PAC promoter elements correlated with nutrient responsiveness and a dynamic pattern of histone occupancy and acetylation. Correlative evidence supports the idea that some mRNAs may be upregulated by release from sequestration in RNA-protein complexes.

  2. Mechanical Stress Regulation of Plant Growth and Development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.

    1985-01-01

    Growth dynamics analysis was used to determine to what extent the seismic stress induced reduction in photosynthetic productivity in shaken soybeans was due to less photosynthetic surface, and to what extent to lower efficiency of assimulation. Seismic stress reduces shoot transpiration rate 17% and 15% during the first and second 45 minute periods following a given treatment. Shaken plants also had a 36% greater leaf water potential 30 minutes after treatment. Continuous measurement of whole plant photosynthetic rate shows that a decline in CO2 fixation began within seconds after the onset of shaking treatment and continued to decline to 16% less than that of controls 20 minutes after shaking, after which gradual recovery of photosynthesis begins. Photosynthetic assimilation recovered completely before the next treatment 5 hours later. The transitory decrease in photosynthetic rate was due entirely to a two fold increase in stomatal resistance to CO2 by the abaxial leaf surface. Mesophyll resistance was not significantly affected by periodic seismic treatment. Temporary stomatal aperture reduction and decreased CO2 fixation are responsible for the lower dry weight of seismic stressed plants growing in a controlled environment.

  3. Systemic regulation of soybean nodulation by acidic growth conditions.

    PubMed

    Lin, Meng-Han; Gresshoff, Peter M; Ferguson, Brett J

    2012-12-01

    Mechanisms inhibiting legume nodulation by low soil pH, although highly prevalent and economically significant, are poorly understood. We addressed this in soybean (Glycine max) using a combination of physiological and genetic approaches. Split-root and grafting studies using an autoregulation-of-nodulation-deficient mutant line, altered in the autoregulation-of-nodulation receptor kinase GmNARK, determined that a systemic, shoot-controlled, and GmNARK-dependent mechanism was critical for facilitating the inhibitory effect. Acid inhibition was independent of aluminum ion concentration and occurred early in nodule development, between 12 and 96 h post inoculation with Bradyrhizobium japonicum. Biological effects were confirmed by measuring transcript numbers of known early nodulation genes. Transcripts decreased on both sides of split-root systems, where only one side was subjected to low-pH conditions. Our findings enhance the present understanding of the innate mechanisms regulating legume nodulation control under acidic conditions, which could benefit future attempts in agriculture to improve nodule development and biological nitrogen fixation in acid-stressed soils.

  4. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective.

    PubMed

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-08-19

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth.

  5. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    PubMed Central

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  6. The roles of placental growth hormone and placental lactogen in the regulation of human fetal growth and development.

    PubMed

    Handwerger, S; Freemark, M

    2000-04-01

    The human growth hormone (hGH)/human placental lactogen (hPL) gene family, which consists of two GH and three PL genes, is important in the regulation of maternal and fetal metabolism and the growth and development of the fetus. During pregnancy, pituitary GH (hGH-N) expression in the mother is suppressed; and hGH-V, a GH variant expressed by the placenta, becomes the predominant GH in the mother. hPL, which is the product of the hPL-A and hPL-B genes, is secreted into both the maternal and fetal circulations after the sixth week of pregnancy. hGH-V and hPL act in concert in the mother to stimulate insulin-like growth factor (IGF) production and modulate intermediary metabolism, resulting in an increase in the availability of glucose and amino acids to the fetus. In the fetus, hPL acts via lactogenic receptors and possibly a unique PL receptor to modulate embryonic development, regulate intermediary metabolism and stimulate the production of IGFs, insulin, adrenocortical hormones and pulmonary surfactant. hGH-N, which is expressed by the fetal pituitary, has little or no physiological actions in the fetus until late in pregnancy due to the lack of functional GH receptors on fetal tissues. hGH-V, which is also a potent somatogenic hormone, is not released into the fetus. Taken together, studies of the hGH/hPL gene family during pregnancy reveal a complex interaction of the hormones with one another and with other growth factors. Additional investigations are necessary to clarify the relative roles of the family members in the regulation of fetal growth and development and the factors that modulate the expression of the genes.

  7. Integrin β1 regulates leiomyoma cytoskeletal integrity and growth

    PubMed Central

    Malik, Minnie; Segars, James; Catherino, William H.

    2014-01-01

    Uterine leiomyomas are characterized by an excessive extracellular matrix, increased mechanical stress, and increased active RhoA. Previously, we observed that mechanical signaling was attenuated in leiomyoma, but the mechanisms responsible remain unclear. Integrins, especially integrin β1, are transmembrane adhesion receptors that couple extracellular matrix stresses to the intracellular cytoskeleton to influence cell proliferation and differentiation. Here we characterized integrin and laminin to signaling in leiomyoma cells. We observed a 2.25 ± 0.32 fold increased expression of integrin β1 in leiomyoma cells, compared to myometrial cells. Antibody-mediated inhibition of integrin β1 led to significant growth inhibition in leiomyoma cells and a loss of cytoskeletal integrity. Specifically, polymerization of actin filaments and formation of focal adhesions were reduced by inhibition of integrin p1. Inhibition of integrin β1 in leiomyoma cells led to 0.81 ± 0.02 fold decrease in active RhoA, and resembled levels found in serum-starved cells. Likewise, inhibition of integrin β1 was accompanied by a decrease in phospho-ERK. Compared to myometrial cells, leiomyoma cells demonstrated increased expression of integrin α6 subunit to laminin receptor (1.91 ± 0.11 fold), and increased expression of laminin 5α (1.52±0.02), laminin 5β (3.06±0.92), and laminin 5γ (1.66 ± 0.06). Of note, leiomyoma cells grown on laminin matrix appear to realign themselves. Taken together, the findings reveal that the attenuated mechanical signaling in leiomyoma cells is accompanied by an increased expression and a dependence on integrin β1 signaling in leiomyoma cells, compared to myometrial cells. PMID:23023061

  8. GSK3β Regulates Differentiation and Growth Arrest in Glioblastoma

    PubMed Central

    Korur, Serdar; Huber, Roland M.; Sivasankaran, Balasubramanian; Petrich, Michael; Morin, Pier; Hemmings, Brian A.; Merlo, Adrian; Lino, Maria Maddalena

    2009-01-01

    Cancers are driven by a population of cells with the stem cell properties of self-renewal and unlimited growth. As a subpopulation within the tumor mass, these cells are believed to constitute a tumor cell reservoir. Pathways controlling the renewal of normal stem cells are deregulated in cancer. The polycomb group gene Bmi1, which is required for neural stem cell self-renewal and also controls anti-oxidant defense in neurons, is upregulated in several cancers, including medulloblastoma. We have found that Bmi1 is consistently and highly expressed in GBM. Downregulation of Bmi1 by shRNAs induced a differentiation phenotype and reduced expression of the stem cell markers Sox2 and Nestin. Interestingly, expression of glycogen synthase kinase 3 beta (GSK3β), which was found to be consistently expressed in primary GBM, also declined. This suggests a functional link between Bmi1 and GSK3β. Interference with GSK3β activity by siRNA, the specific inhibitor SB216763, or lithium chloride (LiCl) induced tumor cell differentiation. In addition, tumor cell apoptosis was enhanced, the formation of neurospheres was impaired, and clonogenicity reduced in a dose-dependent manner. GBM cell lines consist mainly of CD133-negative (CD133-) cells. Interestingly, ex vivo cells from primary tumor biopsies allowed the identification of a CD133- subpopulation of cells that express stem cell markers and are depleted by inactivation of GSK3β. Drugs that inhibit GSK3, including the psychiatric drug LiCl, may deplete the GBM stem cell reservoir independently of CD133 status. PMID:19823589

  9. Intrinsic-mediated caspase activation is essential for cardiomyocyte hypertrophy.

    PubMed

    Putinski, Charis; Abdul-Ghani, Mohammad; Stiles, Rebecca; Brunette, Steve; Dick, Sarah A; Fernando, Pasan; Megeney, Lynn A

    2013-10-22

    Cardiomyocyte hypertrophy is the cellular response that mediates pathologic enlargement of the heart. This maladaptation is also characterized by cell behaviors that are typically associated with apoptosis, including cytoskeletal reorganization and disassembly, altered nuclear morphology, and enhanced protein synthesis/translation. Here, we investigated the requirement of apoptotic caspase pathways in mediating cardiomyocyte hypertrophy. Cardiomyocytes treated with hypertrophy agonists displayed rapid and transient activation of the intrinsic-mediated cell death pathway, characterized by elevated levels of caspase 9, followed by caspase 3 protease activity. Disruption of the intrinsic cell death pathway at multiple junctures led to a significant inhibition of cardiomyocyte hypertrophy during agonist stimulation, with a corresponding reduction in the expression of known hypertrophic markers (atrial natriuretic peptide) and transcription factor activity [myocyte enhancer factor-2, nuclear factor kappa B (NF-κB)]. Similarly, in vivo attenuation of caspase activity via adenoviral expression of the biologic effector caspase inhibitor p35 blunted cardiomyocyte hypertrophy in response to agonist stimulation. Treatment of cardiomyocytes with procaspase 3 activating compound 1, a small-molecule activator of caspase 3, resulted in a robust induction of the hypertrophy response in the absence of any agonist stimulation. These results suggest that caspase-dependent signaling is necessary and sufficient to promote cardiomyocyte hypertrophy. These results also confirm that cell death signal pathways behave as active remodeling agents in cardiomyocytes, independent of inducing an apoptosis response.

  10. Micropost arrays for measuring stem cell-derived cardiomyocyte contractility

    PubMed Central

    Beussman, Kevin M.; Rodriguez, Marita L.; Leonard, Andrea; Taparia, Nikita; Thompson, Curtis R.; Sniadecki, Nathan J.

    2015-01-01

    Stem cell-derived cardiomyocytes have the potential to be used to study heart disease and maturation, screen drug treatments, and restore heart function. Here, we discuss the procedures involved in using micropost arrays to measure the contractile forces generated by stem cell-derived cardiomyocytes. Cardiomyocyte contractility is needed for the heart to pump blood, so measuring the contractile forces of cardiomyocytes is a straightforward way to assess their function. Microfabrication and soft lithography techniques are utilized to create identical arrays of flexible, silicone microposts from a common master. Micropost arrays are functionalized with extracellular matrix protein to allow cardiomyocytes to adhere to the tips of the microposts. Live imaging is used to capture videos of the deflection of microposts caused by the contraction of the cardiomyocytes. Image analysis code provides an accurate means to quantify these deflections. The contractile forces produced by a beating cardiomyocyte are calculated by modeling the microposts as cantilever beams. We have used this assay to assess techniques for improving the maturation and contractile function of stem cell-derived cardiomyocytes. PMID:26344757

  11. Endogenous rhythmic growth in oak trees is regulated by internal clocks rather than resource availability.

    PubMed

    Herrmann, S; Recht, S; Boenn, M; Feldhahn, L; Angay, O; Fleischmann, F; Tarkka, M T; Grams, T E E; Buscot, F

    2015-12-01

    Common oak trees display endogenous rhythmic growth with alternating shoot and root flushes. To explore the mechanisms involved, microcuttings of the Quercus robur L. clone DF159 were used for (13)C/(15)N labelling in combination with RNA sequencing (RNASeq) transcript profiling of shoots and roots. The effect of plant internal resource availability on the rhythmic growth of the cuttings was tested through inoculation with the ectomycorrhizal fungus Piloderma croceum. Shoot and root flushes were related to parallel shifts in above- and below-ground C and, to a lesser extent, N allocation. Increased plant internal resource availability by P. croceum inoculation with enhanced plant growth affected neither the rhythmic growth nor the associated resource allocation patterns. Two shifts in transcript abundance were identified during root and shoot growth cessation, and most concerned genes were down-regulated. Inoculation with P. croceum suppressed these transcript shifts in roots, but not in shoots. To identify core processes governing the rhythmic growth, functions [Gene Ontology (GO) terms] of the genes differentially expressed during the growth cessation in both leaves and roots of non-inoculated plants and leaves of P. croceum-inoculated plants were examined. Besides genes related to resource acquisition and cell development, which might reflect rather than trigger rhythmic growth, genes involved in signalling and/or regulated by the circadian clock were identified. The results indicate that rhythmic growth involves dramatic oscillations in plant metabolism and gene regulation between below- and above-ground parts. Ectomycorrhizal symbiosis may play a previously unsuspected role in smoothing these oscillations without modifying the rhythmic growth pattern.

  12. Regulation of voltage-gated sodium channel expression in cancer: hormones, growth factors and auto-regulation.

    PubMed

    Fraser, Scott P; Ozerlat-Gunduz, Iley; Brackenbury, William J; Fitzgerald, Elizabeth M; Campbell, Thomas M; Coombes, R Charles; Djamgoz, Mustafa B A

    2014-03-19

    Although ion channels are increasingly being discovered in cancer cells in vitro and in vivo, and shown to contribute to different aspects and stages of the cancer process, much less is known about the mechanisms controlling their expression. Here, we focus on voltage-gated Na(+) channels (VGSCs) which are upregulated in many types of carcinomas where their activity potentiates cell behaviours integral to the metastatic cascade. Regulation of VGSCs occurs at a hierarchy of levels from transcription to post-translation. Importantly, mainstream cancer mechanisms, especially hormones and growth factors, play a significant role in the regulation. On the whole, in major hormone-sensitive cancers, such as breast and prostate cancer, there is a negative association between genomic steroid hormone sensitivity and functional VGSC expression. Activity-dependent regulation by positive feedback has been demonstrated in strongly metastatic cells whereby the VGSC is self-sustaining, with its activity promoting further functional channel expression. Such auto-regulation is unlike normal cells in which activity-dependent regulation occurs mostly via negative feedback. Throughout, we highlight the possible clinical implications of functional VGSC expression and regulation in cancer.

  13. Acoustical sensing of cardiomyocyte cluster beating

    SciTech Connect

    Tymchenko, Nina; Kunze, Angelika; Dahlenborg, Kerstin; Svedhem, Sofia; Steel, Daniella

    2013-06-14

    Highlights: •An example of the application of QCM-D to live cell studies. •Detection of human pluripotent stem cell-derived cardiomyocyte cluster beating. •Clusters were studied in a thin liquid film and in a large liquid volume. •The QCM-D beating profile provides an individual fingerprint of the hPS-CMCs. -- Abstract: Spontaneously beating human pluripotent stem cell-derived cardiomyocytes clusters (CMCs) represent an excellent in vitro tool for studies of human cardiomyocyte function and for pharmacological cardiac safety assessment. Such testing typically requires highly trained operators, precision plating, or large cell quantities, and there is a demand for real-time, label-free monitoring of small cell quantities, especially rare cells and tissue-like structures. Array formats based on sensing of electrical or optical properties of cells are being developed and in use by the pharmaceutical industry. A potential alternative to these techniques is represented by the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, which is an acoustic surface sensitive technique that measures changes in mass and viscoelastic properties close to the sensor surface (from nm to μm). There is an increasing number of studies where QCM-D has successfully been applied to monitor properties of cells and cellular processes. In the present study, we show that spontaneous beating of CMCs on QCM-D sensors can be clearly detected, both in the frequency and the dissipation signals. Beating rates in the range of 66–168 bpm for CMCs were detected and confirmed by simultaneous light microscopy. The QCM-D beating profile was found to provide individual fingerprints of the hPS-CMCs. The presented results point towards acoustical assays for evaluation cardiotoxicity.

  14. Human Endometrial Adenocarcinoma Transplanted into Nude Mice: Growth Regulation by Estradiol

    NASA Astrophysics Data System (ADS)

    Satyaswaroop, P. G.; Zaino, R. J.; Mortel, R.

    1983-01-01

    A model for studying the growth of primary tumors of human endometrium and its regulation by 17β -estradiol has been developed in which ovariectomized nude mice are used as recipients. The receptors for sex steroids are maintained during serial transplantation of the tumor in this system. Although the rate of growth of receptor-negative endometrial tumors transplanted into ovariectomized nude mice is unaffected by the sustained presence or absence of estradiol, the growth of receptor-positive tumors is significantly increased by estradiol. Receptor-positive tumors treated with estradiol produced elevated concentrations of progesterone receptor. That the progesterone receptor is functional in this tumor is evident from the induction of estradiol 17β -dehydrogenase activity upon progestin administration. These findings are consistent with receptor-mediated regulation of growth of endometrial carcinoma.

  15. Role of mga in growth phase regulation of virulence genes of the group A streptococcus.

    PubMed Central

    McIver, K S; Scott, J R

    1997-01-01

    To determine whether growth phase affects the expression of mga and other virulence-associated genes in the group A streptococcus (GAS), total RNA was isolated from the serotype M6 GAS strain JRS4 at different phases of growth and transcript levels were quantitated by hybridization with radiolabeled DNA probes. Expression of mga (which encodes a multiple gene regulator) and the Mga-regulated genes emm (which encodes M protein) and scpA (which encodes a complement C5a peptidase) was found to be maximal in exponential phase and shut off as the bacteria entered stationary phase, while the housekeeping genes recA and rpsL showed constant transcript levels over the same period of growth. Expression of mga from a foreign phage promoter in a mga-deleted GAS strain (JRS519) altered the wild-type growth phase-dependent transcription profile seen for emm and scpA, as well as for mga. Therefore, the temporal control of mga expression requires its upstream promoter region, and the subsequent growth phase regulation of emm and scpA is Mga dependent. A number of putative virulence genes in JRS4 were shown not to require Mga for their expression, although several exhibited growth phase-dependent regulation that was similar to mga, i.e., slo (which encodes streptolysin O) and plr (encoding the plasmin receptor/glyceraldehyde-3-phosphate dehydrogenase). Still others showed a markedly different pattern of expression (the genes for the superantigen toxins MF and SpeC). These results suggest the existence of complex levels of global regulation sensitive to growth phase that directly control the expression of virulence genes and mga in GAS. PMID:9260962

  16. The TIP GROWTH DEFECTIVE1 S-acyl transferase regulates plant cell growth in Arabidopsis.

    PubMed

    Hemsley, Piers A; Kemp, Alison C; Grierson, Claire S

    2005-09-01

    TIP GROWTH DEFECTIVE1 (TIP1) of Arabidopsis thaliana affects cell growth throughout the plant and has a particularly strong effect on root hair growth. We have identified TIP1 by map-based cloning and complementation of the mutant phenotype. TIP1 encodes an ankyrin repeat protein with a DHHC Cys-rich domain that is expressed in roots, leaves, inflorescence stems, and floral tissue. Two homologues of TIP1 in yeast (Saccharomyces cerevisiae) and human (Homo sapiens) have been shown to have S-acyl transferase (also known as palmitoyl transferase) activity. S-acylation is a reversible hydrophobic protein modification that offers swift, flexible control of protein hydrophobicity and affects protein association with membranes, signal transduction, and vesicle trafficking within cells. We show that TIP1 binds the acyl group palmitate, that it can rescue the morphological, temperature sensitivity, and yeast casein kinase2 localization defects of the yeast S-acyl transferase mutant akr1Delta, and that inhibition of acylation in wild-type Arabidopsis roots reproduces the Tip1- mutant phenotype. Our results demonstrate that S-acylation is essential for normal plant cell growth and identify a plant S-acyl transferase, an essential research tool if we are to understand how this important, reversible lipid modification operates in plant cells.

  17. Upregulation of phase II enzymes through phytochemical activation of Nrf2 protects cardiomyocytes against oxidant stress.

    PubMed

    Reuland, Danielle J; Khademi, Shadi; Castle, Christopher J; Irwin, David C; McCord, Joe M; Miller, Benjamin F; Hamilton, Karyn L

    2013-03-01

    Increased production of reactive oxygen species has been implicated in the pathogenesis of cardiovascular disease (CVD), and enhanced endogenous antioxidants have been proposed as a mechanism for regulating redox balance. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a transcriptional regulator of phase II antioxidant enzymes, and activation of Nrf2 has been suggested to be an important step in attenuating oxidative stress associated with CVD. A well-defined combination of five widely studied medicinal plants derived from botanical sources (Bacopa monniera, Silybum marianum (milk thistle), Withania somnifera (Ashwagandha), Camellia sinensis (green tea), and Curcuma longa (turmeric)) has been shown to activate Nrf2 and induce phase II enzymes through the antioxidant response element. The purpose of these experiments was to determine if treatment of cardiomyocytes with this phytochemical composition, marketed as Protandim, activates Nrf2, induces phase II detoxification enzymes, and protects cardiomyocytes from oxidant-induced apoptosis in a Nrf2-dependent manner. In cultured HL-1 cardiomyocytes, phytochemical treatment was associated with nuclear accumulation of Nrf2, significant induction of phase II enzymes, and concomitant protection against hydrogen peroxide-induced apoptosis. The protection against oxidant stress was abolished when Nrf2 was silenced by shRNA, suggesting that our phytochemical treatment worked through the Nrf2 pathway. Interestingly, phytochemical treatment was found to be a more robust activator of Nrf2 than oxidant treatment, supporting the use of the phytochemicals as a potential treatment to increase antioxidant defenses and protect heart cells against an oxidative challenge.

  18. Growth Hormone-Regulated mRNAs and miRNAs in Chicken Hepatocytes

    PubMed Central

    Wang, Huijuan; Shao, Fang; Yu, JianFeng; Jiang, Honglin; Han, Yaoping; Gong, Daoqing; Gu, Zhiliang

    2014-01-01

    Growth hormone (GH) is a key regulatory factor in animal growth, development and metabolism. Based on the expression level of the GH receptor, the chicken liver is a major target organ of GH, but the biological effects of GH on the chicken liver are not fully understood. In this work we identified mRNAs and miRNAs that are regulated by GH in primary hepatocytes from female chickens through RNA-seq, and analyzed the functional relevance of these mRNAs and miRNAs through GO enrichment analysis and miRNA target prediction. A total of 164 mRNAs were found to be differentially expressed between GH-treated and control chicken hepatocytes, of which 112 were up-regulated and 52 were down-regulated by GH. A total of 225 chicken miRNAs were identified by the RNA-Seq analysis. Among these miRNAs 16 were up-regulated and 1 miRNA was down-regulated by GH. The GH-regulated mRNAs were mainly involved in growth and metabolism. Most of the GH-upregulated or GH-downregulated miRNAs were predicted to target the GH-downregulated or GH-upregulated mRNAs, respectively, involved in lipid metabolism. This study reveals that GH regulates the expression of many mRNAs involved in metabolism in female chicken hepatocytes, which suggests that GH plays an important role in regulating liver metabolism in female chickens. The results of this study also support the hypothesis that GH regulates lipid metabolism in chicken liver in part by regulating the expression of miRNAs that target the mRNAs involved in lipid metabolism. PMID:25386791

  19. Enhanced animal growth via ligand-regulated GHRH myogenic-injectable vectors

    NASA Technical Reports Server (NTRS)

    Draghia-Akli, Ruxandra; Malone, P. Brandon; Hill, Leigh Anne; Ellis, Kenneth M.; Schwartz, Robert J.; Nordstrom, Jeffrey L.

    2002-01-01

    Regulated animal growth occurred following a single electroporated injection of a mixture of two plasmids (10 microg of DNA), one expressing the GeneSwitch regulator protein, the other an inducible growth hormone releasing hormone (GHRH) gene, into the tibialis anterior muscles of adult SCID mice. Administration of the ligand mifepristone (MFP) up-regulated GHRH expression, as shown by elevations of IGF-I levels, and when MFP dosing was withdrawn, IGF-I returned to baseline levels. Five cycles of IGF-I induction were observed during a five-month period. Chronic MFP dosing for 25 days increased lean body mass, weight gain, and bone mineral density significantly compared with non-MFP treated controls. In summary, long-term drug-regulated GHRH expression was achieved following plasmid-based gene therapy, and chronic induction of GHRH expression in adult animals led to improvements in weight gain and body composition.

  20. Recent Insights into Insulin-Like Growth Factor Binding Protein 2 Transcriptional Regulation

    PubMed Central

    Park, Jae-Hyung; Bae, Jae-Hoon; Song, Dae-Kyu

    2017-01-01

    Insulin-like growth factor binding proteins (IGFBPs) are major regulators of insulin-like growth factor bioavailability and activity in metabolic signaling. Seven IGFBP family isoforms have been identified. Recent studies have shown that IGFBPs play a pivotal role in metabolic signaling and disease, including the pathogenesis of obesity, diabetes, and cancer. Although many studies have documented the various roles played by IGFBPs, transcriptional regulation of IGFBPs is not well understood. In this review, we focus on the regulatory mechanisms of IGFBP gene expression, and we summarize the findings of transcription factor activity in the IGFBP promoter region. PMID:28116872

  1. Growth Arrest Specific 2 Is Up-Regulated in Chronic Myeloid Leukemia Cells and Required for Their Growth

    PubMed Central

    Ma, Wenjuan; Wu, Jie; Zhang, Xiuyan; Hu, Xiaohui; Eaves, Connie J.; Wu, Depei; Zhao, Yun

    2014-01-01

    Although the generation of BCR-ABL is the molecular hallmark of chronic myeloid leukemia (CML), the comprehensive molecular mechanisms of the disease remain unclear yet. Growth arrest specific 2 (GAS2) regulates multiple cellular functions including cell cycle, apoptosis and calpain activities. In the present study, we found GAS2 was up-regulated in CML cells including CD34+ progenitor cells compared to their normal counterparts. We utilized RNAi and the expression of dominant negative form of GAS2 (GAS2DN) to target GAS2, which resulted in calpain activity enhancement and growth inhibition of both K562 and MEG-01 cells. Targeting GAS2 also sensitized K562 cells to Imatinib mesylate (IM). GAS2DN suppressed the tumorigenic ability of MEG-01 cells and impaired the tumour growth as well. Moreover, the CD34+ cells from CML patients and healthy donors were transduced with control and GAS2DN lentiviral vectors, and the CD34+ transduced (YFP+) progeny cells (CD34+YFP+) were plated for colony-forming cell (CFC) assay. The results showed that GAS2DN inhibited the CFC production of CML cells by 57±3% (n = 3), while affected those of normal hematopoietic cells by 31±1% (n = 2). Next, we found the inhibition of CML cells by GAS2DN was dependent on calpain activity but not the degradation of beta-catenin. Lastly, we generated microarray data to identify the differentially expressed genes upon GAS2DN and validated that the expression of HNRPDL, PTK7 and UCHL5 was suppressed by GAS2DN. These 3 genes were up-regulated in CML cells compared to normal control cells and the growth of K562 cells was inhibited upon HNRPDL silence. Taken together, we have demonstrated that GAS2 is up-regulated in CML cells and the inhibition of GAS2 impairs the growth of CML cells, which indicates GAS2 is a novel regulator of CML cells and a potential therapeutic target of this disease. PMID:24465953

  2. Adipocytes, myofibers, and cytokine biology: new horizons in the regulation of growth and body composition.

    PubMed

    Jacobi, S K; Gabler, N K; Ajuwon, K M; Davis, J E; Spurlock, M E

    2006-04-01

    Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Therefore, understanding the impact of stress and disease on muscle growth is essential to improving production efficiency. The adipocyte in particular seems to be well positioned as an interface between energy status and immune function, and may thus influence nutrient partitioning and growth through a combination of signals that influence fat metabolism, glucose uptake, and insulin sensitivity. Adipocytes and myofibers are active participants in the innate immune response, and as such, produce a number of metabolic regulators, including leptin, adiponectin, and proinflammatory cytokines. Specifically, adipocytes and muscle cells respond directly to bacterial lipopolysaccharide (LPS) by producing interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha). However, adipocytes are also the predominant source of the antiinflammatory hormone adiponectin, which regulates the nuclear factor kappa-B transcription factor. The ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally, and to reciprocally regulate metabolism peripherally.

  3. Regulation of PTHrP expression by cyclic mechanical strain in postnatal growth plate chondrocytes.

    PubMed

    Xu, Tao; Yang, Kaixiang; You, Hongbo; Chen, Anmin; Wang, Jiang; Xu, Kai; Gong, Chen; Shao, Jingfan; Ma, Zhongxi; Guo, Fengjing; Qi, Jun

    2013-10-01

    Mechanical loading has been widely considered to be a crucial regulatory factor for growth plate development, but the exact mechanisms of this regulation are still not completely understood. In the growth plate, parathyroid hormone-related protein (PTHrP) regulates chondrocyte differentiation and longitudinal growth. Cyclic mechanical strain has been demonstrated to influence growth plate chondrocyte differentiation and metabolism, whereas the relationship between cyclic mechanical strain and PTHrP expression is not clear. The objective of this study was to investigate whether short-term cyclic tensile strain regulates PTHrP expression in postnatal growth plate chondrocytes in vitro and to explore whether the organization of cytoskeletal F-actin microfilaments is involved in this process. To this end, we obtained growth plate chondrocytes from 2-week-old Sprague-Dawley rats and sorted prehypertrophic and hypertrophic chondrocytes using immunomagnetic beads coated with anti-CD200 antibody. The sorted chondrocytes were subjected to cyclic tensile strain of varying magnitude and duration at a frequency of 0.5 Hz. We found that cyclic strain regulates PTHrP expression in a magnitude- and time-dependent manner. Incubation of chondrocytes with cytochalasin D, an actin microfilament-disrupting reagent, blocked the induction of PTHrP expression in response to strain. The results suggest that short-term cyclic tensile strain induces PTHrP expression in postnatal growth plate prehypertrophic and hypertrophic chondrocytes and that PTHrP expression by these chondrocytes may subsequently affect growth plate development. The results also support the idea that the organization of cytoskeletal F-actin microfilaments plays an important role in mechanotransduction.

  4. Pluripotent Stem Cell Derived Cardiomyocytes for Cardiac Repair

    PubMed Central

    Lundy, Scott D.; Gantz, Jay A.; Pagan, Chelsea M.; Filice, Dominic; Laflamme, Michael A.

    2014-01-01

    Opinion Statement The adult mammalian heart has limited capacity for generation, so a major injury such as a myocardial infarction results in the permanent loss of up to one billion cardiomyocytes. The field of cardiac cell therapy aims to replace these lost contractile units with de novo cardiomyocytes to restore lost systolic function and prevent progression to heart failure. Arguably the ideal cell for this application is the human cardiomyocyte itself, which can electromechanically couple with host myocardium and contribute active systolic force. Pluripotent stem cells from both human embryonic or induced pluripotent lineages are attractive sources for cardiomyocytes, and preclinical investigation of these cells is in progress. Recent work has focused on efficient generation and purification of cardiomyocytes, tissue engineering efforts, and examining the consequences of cell transplantation from mechanical, vascular, and electrical standpoints. Here we discuss historical and contemporary aspects of pluripotent stem cell-based cardiac cell therapy, with an emphasis on recent preclinical studies with translational goals. PMID:24838687

  5. Target of Rapamycin (TOR) Regulates Growth in Response to Nutritional Signals.

    PubMed

    Weisman, Ronit

    2016-10-01

    All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.

  6. Novel targets of sulforaphane in primary cardiomyocytes identified by proteomic analysis.

    PubMed

    Angeloni, Cristina; Turroni, Silvia; Bianchi, Laura; Fabbri, Daniele; Motori, Elisa; Malaguti, Marco; Leoncini, Emanuela; Maraldi, Tullia; Bini, Luca; Brigidi, Patrizia; Hrelia, Silvana

    2013-01-01

    Cardiovascular diseases represent the main cause of mortality in the industrialized world and the identification of effective preventive strategies is of fundamental importance. Sulforaphane, an isothiocyanate from cruciferous vegetables, has been shown to up-regulate phase II enzymes in cardiomyocytes and counteract oxidative stress-induced apoptosis. Aim of the present study was the identification and characterization of novel sulforaphane targets in cardiomyocytes applying a proteomic approach. Two-dimensional gel electrophoresis and mass spectrometry were used to generate protein profiles of primary neonatal rat cardiomyocytes treated and untreated with 5 µM sulforaphane for 1-48 h. According to image analysis, 64 protein spots were found as differentially expressed and their functional correlations were investigated using the MetaCore program. We mainly focused on 3 proteins: macrophage migration inhibitory factor (MIF), CLP36 or Elfin, and glyoxalase 1, due to their possible involvement in cardioprotection. Validation of the time-dependent differential expression of these proteins was performed by western blotting. In particular, to gain insight into the cardioprotective role of the modulation of glyoxalase 1 by sulforaphane, further experiments were performed using methylglyoxal to mimic glycative stress. Sulforaphane was able to counteract methylglyoxal-induced apoptosis, ROS production, and glycative stress, likely through glyoxalase 1 up-regulation. In this study, we reported for the first time new molecular targets of sulforaphane, such as MIF, CLP36 and glyoxalase 1. In particular, we gave new insights into the anti-glycative role of sulforaphane in cardiomyocytes, confirming its pleiotropic behavior in counteracting cardiovascular diseases.

  7. Novel Targets of Sulforaphane in Primary Cardiomyocytes Identified by Proteomic Analysis

    PubMed Central

    Angeloni, Cristina; Turroni, Silvia; Bianchi, Laura; Fabbri, Daniele; Motori, Elisa; Malaguti, Marco; Leoncini, Emanuela; Maraldi, Tullia; Bini, Luca; Brigidi, Patrizia; Hrelia, Silvana

    2013-01-01

    Cardiovascular diseases represent the main cause of mortality in the industrialized world and the identification of effective preventive strategies is of fundamental importance. Sulforaphane, an isothiocyanate from cruciferous vegetables, has been shown to up-regulate phase II enzymes in cardiomyocytes and counteract oxidative stress-induced apoptosis. Aim of the present study was the identification and characterization of novel sulforaphane targets in cardiomyocytes applying a proteomic approach. Two-dimensional gel electrophoresis and mass spectrometry were used to generate protein profiles of primary neonatal rat cardiomyocytes treated and untreated with 5 µM sulforaphane for 1-48 h. According to image analysis, 64 protein spots were found as differentially expressed and their functional correlations were investigated using the MetaCore program. We mainly focused on 3 proteins: macrophage migration inhibitory factor (MIF), CLP36 or Elfin, and glyoxalase 1, due to their possible involvement in cardioprotection. Validation of the time-dependent differential expression of these proteins was performed by western blotting. In particular, to gain insight into the cardioprotective role of the modulation of glyoxalase 1 by sulforaphane, further experiments were performed using methylglyoxal to mimic glycative stress. Sulforaphane was able to counteract methylglyoxal-induced apoptosis, ROS production, and glycative stress, likely through glyoxalase 1 up-regulation. In this study, we reported for the first time new molecular targets of sulforaphane, such as MIF, CLP36 and glyoxalase 1. In particular, we gave new insights into the anti-glycative role of sulforaphane in cardiomyocytes, confirming its pleiotropic behavior in counteracting cardiovascular diseases. PMID:24349480

  8. Nav1.5 regulates breast tumor growth and metastatic dissemination in vivo.

    PubMed

    Nelson, Michaela; Yang, Ming; Millican-Slater, Rebecca; Brackenbury, William J

    2015-10-20

    Voltage-gated Na+ channels (VGSCs) mediate action potential firing and regulate adhesion and migration in excitable cells. VGSCs are also expressed in cancer cells. In metastatic breast cancer (BCa) cells, the Nav1.5 α subunit potentiates migration and invasion. In addition, the VGSC-inhibiting antiepileptic drug phenytoin inhibits tumor growth and metastasis. However, the functional activity of Nav1.5 and its specific contribution to tumor progression in vivo has not been delineated. Here, we found that Nav1.5 is up-regulated at the protein level in BCa compared with matched normal breast tissue. Na+ current, reversibly blocked by tetrodotoxin, was retained in cancer cells in tumor tissue slices, thus directly confirming functional VGSC activity in vivo. Stable down-regulation of Nav1.5 expression significantly reduced tumor growth, local invasion into surrounding tissue, and metastasis to liver, lungs and spleen in an orthotopic BCa model. Nav1.5 down-regulation had no effect on cell proliferation or angiogenesis within the in tumors, but increased apoptosis. In vitro, Nav1.5 down-regulation altered cell morphology and reduced CD44 expression, suggesting that VGSC activity may regulate cellular invasion via the CD44-src-cortactin signaling axis. We conclude that Nav1.5 is functionally active in cancer cells in breast tumors, enhancing growth and metastatic dissemination. These findings support the notion that compounds targeting Nav1.5 may be useful for reducing metastasis.

  9. Monovalent Cations and Growth Regulation. I. Growth Responses in Cucumber Hypocotyl Segments 1

    PubMed Central

    Purves, William K.

    1966-01-01

    The elongation of etiolated cucumber (Cucumis sativus L.) hypocotyl segments was stimulated by KCl and a number of other potassium salts at a concentration of 0.02 n K+. The effect of KCl was not evident until 14 hours after the beginning of treatment. NaCl, LiCl, and RbCl enhanced elongation of the segments, and their dosage-response curves were similar to that for KCl. At supraoptimal concentrations (≥ 0.05 m), LiCl inhibited segment growth. CsCl was inhibitory at all concentrations tested and was thus the only alkali metal cation to lack growth-promoting activity in this system. NH4Cl also promoted elongation, but not as effectively as did the alkali cations. CaCl2, CoCl2, and MgCl2 did not enhance growth when tested at the same concentrations as the monovalent cations. CoCl2 promoted strongly at 103 m, and NiCl2 was slightly active at 10−4 m. It is suggested that the nutritional requirement for K in higher plants results from a specific involvement in certain enzyme systems and from a relatively nonspecific role related to the elongation response described here. PMID:16656244

  10. A multilevel latent growth modelling of the longitudinal changes in motivation regulations in physical education.

    PubMed

    Jaakkola, Timo; Wang, John; Yli-Piipari, Sami; Liukkonen, Jarmo

    2015-03-01

    The purpose of this study was to examine individual- and classroom-level differences in the longitudinal change in motivational regulations during physical education students' transition from elementary (Grade 6) across middle school (Grades 7 to 9). A sample of 757 Finnish adolescents (M = 12.71, SD = 0.23) participated in this study. Participants of the study responded to questionnaires collected six times. A multilevel latent growth modelling approach was used to analyze the data. Results showed that motivational regulations in physical education developed at different rates during middle school. More specifically, students': (a) identified regulation increased across Grades 6 to 9; (b) amotivation increased during middle school transition from Grade 6 to 7; and (c) introjected regulation declined from Grade 8 to 9. Other motivational regulations remained stable across time. The changes in amotivation and introjected regulation were largely due to individual factors, whereas the changes in identified regulation were due to environmental factors. Key pointsStudents' identified regulation increased across Grades 6 to 9.Students' amotivation increased across middle school transition from Grade 6 to 7.Students' introjected regulation declined from Grade 8 to 9.Other motivational regulations remained stable across time.

  11. Chronic coexistence of two troponin T isoforms in adult transgenic mouse cardiomyocytes decreased contractile kinetics and caused dilatative remodeling.

    PubMed

    Yu, Zhi-Bin; Wei, Hongguang; Jin, J-P

    2012-07-01

    Our previous in vivo and ex vivo studies suggested that coexistence of two or more troponin T (TnT) isoforms in adult cardiac muscle decreased cardiac function and efficiency (Huang QQ, Feng HZ, Liu J, Du J, Stull LB, Moravec CS, Huang X, Jin JP, Am J Physiol Cell Physiol 294: C213-C22, 2008; Feng HZ, Jin JP, Am J Physiol Heart Circ Physiol 299: H97-H105, 2010). Here we characterized Ca(2+)-regulated contractility of isolated adult cardiomyocytes from transgenic mice coexpressing a fast skeletal muscle TnT together with the endogenous cardiac TnT. Without the influence of extracellular matrix, coexistence of the two TnT isoforms resulted in lower shortening amplitude, slower shortening and relengthening velocities, and longer relengthening time. The level of resting cytosolic Ca(2+) was unchanged, but the peak Ca(2+) transient was lowered and the durations of Ca(2+) rising and decaying were longer in the transgenic mouse cardiomyocytes vs. the wild-type controls. Isoproterenol treatment diminished the differences in shortening amplitude and shortening and relengthening velocities, whereas the prolonged durations of relengthening and Ca(2+) transient in the transgenic cardiomyocytes remained. At rigor state, a result from depletion of Ca(2+), resting sarcomere length of the transgenic cardiomyocytes became shorter than that in wild-type cells. Inhibition of myosin motor diminished this effect of TnT function on cross bridges. The length but not width of transgenic cardiomyocytes was significantly increased compared with the wild-type controls, corresponding to longitudinal addition of sarcomeres and dilatative remodeling at the cellular level. These dominantly negative effects of normal fast TnT demonstrated that chronic coexistence of functionally distinct variants of TnT in adult cardiomyocytes reduces contractile performance with pathological consequences.

  12. Regulation of early human growth: impact on long-term health.

    PubMed

    Koletzko, Berthold; Chourdakis, Michael; Grote, Veit; Hellmuth, Christian; Prell, Christine; Rzehak, Peter; Uhl, Olaf; Weber, Martina

    2014-01-01

    Growth and development are central characteristics of childhood. Deviations from normal growth can indicate serious health challenges. The adverse impact of early growth faltering and malnutrition on later health has long been known. In contrast, the impact of rapid early weight and body fat gain on programming of later disease risk have only recently received increased attention. Numerous observational studies related diet in early childhood and rapid early growth to the risk of later obesity and associated disorders. Causality was confirmed in a large, double-blind randomised trial testing the 'Early Protein Hypothesis'. In this trial we found that attenuation of protein supply in infancy normalized early growth and markedly reduced obesity prevalence in early school age. These results indicate the need to describe and analyse growth patterns and their regulation through diet in more detail and to characterize the underlying metabolic and epigenetic mechanisms, given the potential major relevance for public health and policy. Better understanding of growth patterns and their regulation could have major benefits for the promotion of public health, consumer-orientated nutrition recommendations, and the development of improved food products for specific target populations.

  13. Emerging role of PLAG1 as a regulator of growth and reproduction.

    PubMed

    Juma, Almas R; Damdimopoulou, Pauliina E; Grommen, Sylvia V H; Van de Ven, Wim J M; De Groef, Bert

    2016-02-01

    Pleomorphic adenoma gene 1 (PLAG1) belongs to the PLAG family of zinc finger transcription factors along with PLAG-like 1 and PLAG-like 2. The PLAG1 gene is best known as an oncogene associated with certain types of cancer, most notably pleomorphic adenomas of the salivary gland. While the mechanisms of PLAG1-induced tumorigenesis are reasonably well understood, the role of PLAG1 in normal physiology is less clear. It is known that PLAG1 is involved in cell proliferation by directly regulating a wide array of target genes, including a number of growth factors such as insulin-like growth factor 2. This is likely to be a central mode of action for PLAG1 both in embryonic development and in cancer. The phenotype of Plag1 knockout mice suggests an important role for PLAG1 also in postnatal growth and reproduction, as PLAG1 deficiency causes growth retardation and reduced fertility. A role for PLAG1 in growth and reproduction is further corroborated by genome-wide association studies in humans and domestic animals in which polymorphisms in the PLAG1 genomic region are associated with body growth and reproductive traits. Here we review the current evidence for PLAG1 as a regulator of growth and fertility and discuss possible endocrine mechanisms involved.

  14. An integrated and disease-oriented growth factor-regulated signal transduction network.

    PubMed

    Erol, A

    2013-01-01

    The importance of Akt, Erk, and their downstream effectors-mediated signaling is indisputable for the proliferation of cell. Growth factor-induced activation of Akt and Erk pathways interacts with each other to regulate proliferation. However, an instructive model, wiring the crucial signaling nodes working in cellular growth and division, is still absent or controversial. Although growth factor-mediated mTORC1 regulation is defined considerably, debates still exist formTORC2. TSC1-TSC2 complex integrates both nutrient and mitogenic signals coming from growth factor receptors. Growth factor-induced PI3K/Akt- and Ras/Erk-mediated TSC2 inhibition is well defined. However, the interaction between TSC complex and new molecules such as Pin1 and DAPK requires further clarifications. Furthermore, the Wnt-β-catenin signaling pathway also intersects with the growth factor signaling at TSC1/TSC2 junction. Therefore, the aim of this perspective paper is to suggest an integrated model, linking growth factor-activated crucial signaling nodes in order to supply key molecular connections to degenerative diseases.

  15. FasL expression in cardiomyocytes activates the ERK1/2 pathway, leading to dilated cardiomyopathy and advanced heart failure.

    PubMed

    Huby, Anne-Cecile; Turdi, Subat; James, Jeanne; Towbin, Jeffrey A; Purevjav, Enkhsaikhan

    2016-02-01

    Increase in the apoptotic molecule Fas ligand (FasL) in serum and cardiomyocytes has been shown to be associated with progressive dilated cardiomyopathy (DCM) and congestive heart failure (CHF) in humans. However, the underlying mechanism(s) of FasL-related deterioration of heart function remain obscure. The aim of the present study is to determine roles of myocardial FasL in the activation of alternative pathways such as extracellular-signal-regulated kinase 1/2 (ERK1/2), inflammation or fibrosis and to identify effective treatments of progressive DCM and advanced CHF. Transgenic mice with cardiomyocyte-specific overexpression of FasL were investigated and treated with an ERK1/2 inhibitor (U-0126), losartan (los), prednisolone (pred) or placebo. Morpho-histological and molecular studies were subsequently performed. FasL mice showed significantly higher mortality compared with wild-type (WT) littermates due to DCM and advanced CHF. Prominent perivascular and interstitial fibrosis, increased interleukin secretion and diffuse CD3-positive cell infiltration were evident in FasL hearts. Up-regulation of the short form of Fas-associated death domain (FADD)-like interleukin 1β-converting enzyme (FLICE) inhibitory protein (s-FLIP), RIP (receptor-interacting protein) and ERK1/2 and down-regulation of transforming growth factor beta 1 (TGFβ1) and nuclear factor-κB (NF-κB) was determined in the myocardium, whereas expression of ERK1/2, periostin (Postn) and osteopontin increased in cardiac fibroblasts. U-0126 and los increased CHF survival by 75% compared with pred and placebo groups. U-0126 had both anti-fibrotic and anti-apoptotic effects, whereas los reduced fibrosis only. Myocardial FasL expression in mice activates differential robust fibrotic, apoptotic and inflammatory responses via ERK1/2 in cardiomyocytes and cardiac fibroblasts inducing DCM and CHF. Blocking the ERK1/2 pathway prevented progression of FasL-induced DCM and CHF by reducing fibrosis, inflammation

  16. TRPC4α and TRPC4β Similarly Affect Neonatal Cardiomyocyte Survival during Chronic GPCR Stimulation

    PubMed Central

    Kirschmer, Nadine; Bandleon, Sandra; von Ehrlich-Treuenstätt, Viktor; Hartmann, Sonja; Schaaf, Alice; Lamprecht, Anna-Karina; Miranda-Laferte, Erick; Langsenlehner, Tanja; Ritter, Oliver; Eder, Petra

    2016-01-01

    The Transient Receptor Potential Channel Subunit 4 (TRPC4) has been considered as a crucial Ca2+ component in cardiomyocytes promoting structural and functional remodeling in the course of pathological cardiac hypertrophy. TRPC4 assembles as homo or hetero-tetramer in the plasma membrane, allowing a non-selective Na+ and Ca2+ influx. Gαq protein-coupled receptor (GPCR) stimulation is known to increase TRPC4 channel activity and a TRPC4-mediated Ca2+ influx which has been regarded as ideal Ca2+ source for calcineurin and subsequent nuclear factor of activated T-cells (NFAT) activation. Functional properties of TRPC4 are also based on the expression of the TRPC4 splice variants TRPC4α and TRPC4β. Aim of the present study was to analyze cytosolic Ca2+ signals, signaling, hypertrophy and vitality of cardiomyocytes in dependence on the expression level of either TRPC4α or TRPC4β. The analysis of Ca2+ transients in neonatal rat cardiomyocytes (NRCs) showed that TRPC4α and TRPC4β affected Ca2+ cycling in beating cardiomyocytes with both splice variants inducing an elevation of the Ca2+ transient amplitude at baseline and TRPC4β increasing the Ca2+ peak during angiotensin II (Ang II) stimulation. NRCs infected with TRPC4β (Ad-C4β) also responded with a sustained Ca2+ influx when treated with Ang II under non-pacing conditions. Consistent with the Ca2+ data, NRCs infected with TRPC4α (Ad-C4α) showed an elevated calcineurin/NFAT activity and a baseline hypertrophic phenotype but did not further develop hypertrophy during chronic Ang II/phenylephrine stimulation. Down-regulation of endogenous TRPC4α reversed these effects, resulting in less hypertrophy of NRCs at baseline but a markedly increased hypertrophic enlargement after chronic agonist stimulation. Ad-C4β NRCs did not exhibit baseline calcineurin/NFAT activity or hypertrophy but responded with an increased calcineurin/NFAT activity after GPCR stimulation. However, this effect was not translated into an

  17. Temporal expression of growth factors triggered by epiregulin regulates inflammation development.

    PubMed

    Harada, Masaya; Kamimura, Daisuke; Arima, Yasunobu; Kohsaka, Hitoshi; Nakatsuji, Yuji; Nishida, Makoto; Atsumi, Toru; Meng, Jie; Bando, Hidenori; Singh, Rajeev; Sabharwal, Lavannya; Jiang, Jing-Jing; Kumai, Noriko; Miyasaka, Nobuyuki; Sakoda, Saburo; Yamauchi-Takihara, Keiko; Ogura, Hideki; Hirano, Toshio; Murakami, Masaaki

    2015-02-01

    In this study, we investigated the relationship between several growth factors and inflammation development. Serum concentrations of epiregulin, amphiregulin, betacellulin, TGF-α, fibroblast growth factor 2, placental growth factor (PLGF), and tenascin C were increased in rheumatoid arthritis patients. Furthermore, local blockades of these growth factors suppressed the development of cytokine-induced arthritis in mice by inhibiting chemokine and IL-6 expressions. We found that epiregulin expression was early and followed by the induction of other growth factors at different sites of the joints. The same growth factors then regulated the expression of epiregulin at later time points of the arthritis. These growth factors were increased in patients suffering from multiple sclerosis (MS) and also played a role in the development of an MS model, experimental autoimmune encephalomyelitis. The results suggest that the temporal expression of growth factors is involved in the inflammation development seen in several diseases, including rheumatoid arthritis and MS. Therefore, various growth factor pathways might be good therapeutic targets for various inflammatory diseases.

  18. Fibroblast growth factor (FGF) signaling regulates transforming growth factor beta (TGFβ)-dependent smooth muscle cell phenotype modulation

    PubMed Central

    Chen, Pei-Yu; Qin, Lingfeng; Li, Guangxin; Tellides, George; Simons, Michael

    2016-01-01

    Smooth muscle cells (SMCs) in normal blood vessels exist in a highly differentiate state characterized by expression of SMC-specific contractile proteins (“contractile phenotype”). Following blood vessel injury in vivo or when cultured in vitro in the presence of multiple growth factors, SMC undergo a phenotype switch characterized by the loss of contractile markers and appearance of expression of non-muscle proteins (“proliferative phenotype”). While a number of factors have been reported to modulate this process, its regulation remains uncertain. Here we show that induction of SMC FGF signaling inhibits TGFβ signaling and converts contractile SMCs to the proliferative phenotype. Conversely, inhibition of SMC FGF signaling induces TGFβ signaling converting proliferating SMCs to the contractile phenotype, even in the presence of various growth factors in vitro or vascular injury in vivo. The importance of this signaling cross-talk is supported by in vivo data that show that an SMC deletion of a pan-FGF receptor adaptor Frs2α (fibroblast growth factor receptor substrate 2 alpha) in mice profoundly reduces neointima formation and vascular remodelling following carotid artery ligation. These results demonstrate that FGF-TGFβ signaling antagonism is the primary regulator of the SMC phenotype switch. Manipulation of this cross-talk may be an effective strategy for treatment of SMC-proliferation related diseases. PMID:27634335

  19. Function of Membrane-Associated Proteoglycans in the Regulation of Satellite Cell Growth.

    PubMed

    Song, Yan

    2016-01-01

    Muscle growth can be divided into embryonic and postnatal periods. During the embryonic period, mesenchymal stem cells proliferate and differentiate to form muscle fibers. Postnatal muscle growth (hypertrophy) is characterized by the enlargement of existing muscle fiber size. Satellite cells (also known as adult myoblasts) are responsible for hypertrophy. The activity of satellite cells can be regulated by their extracellular matrix (ECM). The ECM is composed of collagens, proteoglycans, non-collagenous glycoproteins, cytokines and growth factors. Proteoglycans contain a central core protein with covalently attached glycosaminoglycans (GAGs: chondroitin sulfate, keratan sulfate, dermatan sulfate, and heparan sulfate) and N- or O-linked glycosylation chains. Membrane-associated proteoglycans attach to the cell membrane either through a glycosylphosphatidylinositol anchor or transmembrane domain. The GAGs can bind proteins including cytokines and growth factors. Both cytokines and growth factors play important roles in regulating satellite cell growth and development. Cytokines are generally associated with immune cells. However, cytokines can also affect muscle cell development. For instance, interleukin-6, tumor necrosis factor-α, and leukemia inhibitory factor have been reported to affect the proliferation and differentiation of satellite cells and myoblasts. Growth factors are potent stimulators or inhibitors of satellite cell proliferation and differentiation. The proper function of some cytokines and growth factors requires an interaction with the cell membrane-associated proteoglycans to enhance the affinity to bind to their primary receptors to initiate downstream signal transduction. This chapter is focused on the interaction of membrane-associated proteoglycans with cytokines and growth factors, and their role in satellite cell growth and development.

  20. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon.

    PubMed

    Matos, Dominick A; Cole, Benjamin J; Whitney, Ian P; MacKinnon, Kirk J-M; Kay, Steve A; Hazen, Samuel P

    2014-01-01

    Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.

  1. Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts.

    PubMed

    DiCicco-Bloom, E; Black, I B

    1988-06-01

    While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. We have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase [L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating [3H]thymidine into their nuclei. We used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of [3H]thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis, revealing a 4-fold insulin stimulation with an ED50 of 100 ng/ml. Insulin-like growth factor I was 100-fold more potent than insulin, whereas insulin-like growth factor II was less potent, suggesting that insulin growth factor type I receptors mediated the mitogenic responses. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. Our observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.

  2. Methodology for evaluating the insect growth regulator (IGR) methoprene incorporated into packaging films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The insect growth regulator methoprene has been impregnated onto various packaging materials to control stored product insects, and is labeled for use in this manner in the United States. Different methodologies were utilized to evaluate efficacy towards Tribolium castaneum (Herbst), the red flour b...

  3. Shaping Self-Regulation in Science Teachers' Professional Growth: Inquiry Skills

    ERIC Educational Resources Information Center

    Michalsky, Tova

    2012-01-01

    This study examined 188 preservice science teachers' professional growth along three dimensions--self-regulated learning (SRL) in a science pedagogical context, pedagogical content knowledge, and self-efficacy in teaching science--comparing four learner-centered, active-learning, peer-collaborative environments for learning to teach higher order…

  4. Economics of growth regulator treatment of alfalfa seed for interseeding into silage corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies have focused on interseeding of alfalfa into corn for use as a temporary cover crop rather than as a means of jump-starting alfalfa production after corn. In ongoing field studies, we are evaluating whether plant growth regulators (PGR) may be used to aid the establishment of inters...

  5. Arabidopsis RIC1 Severs Actin Filaments at the Apex to Regulate Pollen Tube Growth

    PubMed Central

    Zhou, Zhenzhen; Shi, Haifan; Chen, Binqing; Zhang, Ruihui; Huang, Shanjin; Fu, Ying

    2015-01-01

    Pollen tubes deliver sperms to the ovule for fertilization via tip growth. The rapid turnover of F-actin in pollen tube tips plays an important role in this process. In this study, we demonstrate that Arabidopsis thaliana RIC1, a member of the ROP-interactive CRIB motif-containing protein family, regulates pollen tube growth via its F-actin severing activity. Knockout of RIC1 enhanced pollen tube elongation, while overexpression of RIC1 dramatically reduced tube growth. Pharmacological analysis indicated that RIC1 affected F-actin dynamics in pollen tubes. In vitro biochemical assays revealed that RIC1 directly bound and severed F-actin in the presence of Ca2+ in addition to interfering with F-actin turnover by capping F-actin at the barbed ends. In vivo, RIC1 localized primarily to the apical plasma membrane (PM) of pollen tubes. The level of RIC1 at the apical PM oscillated during pollen tube growth. The frequency of F-actin severing at the apex was notably decreased in ric1-1 pollen tubes but was increased in pollen tubes overexpressing RIC1. We propose that RIC1 regulates F-actin dynamics at the apical PM as well as the cytosol by severing F-actin and capping the barbed ends in the cytoplasm, establishing a novel mechanism that underlies the regulation of pollen tube growth. PMID:25804540

  6. Rottlerin inhibits cell growth and invasion via down-regulation of Cdc20 in glioma cells

    PubMed Central

    Wang, Lixia; Hou, Yingying; Yin, Xuyuan; Su, Jingna; Zhao, Zhe; Ye, Xiantao; Zhou, Xiuxia; Zhou, Li; Wang, Zhiwei

    2016-01-01

    Rottlerin, isolated from a medicinal plant Mallotus phillippinensis, has been demonstrated to inhibit cellular growth and induce cytoxicity in glioblastoma cell lines through inhibition of calmodulin-dependent protein kinase III. Emerging evidence suggests that rottlerin exerts its antitumor activity as a protein kinase C inhibitor. Although further studies revealed that rottlerin regulated multiple signaling pathways to suppress tumor cell growth, the exact molecular insight on rottlerin-mediated tumor inhibition is not fully elucidated. In the current study, we determine the function of rottlerin on glioma cell growth, apoptosis, cell cycle, migration and invasion. We found that rottlerin inhibited cell growth, migration, invasion, but induced apoptosis and cell cycle arrest. Mechanistically, the expression of Cdc20 oncoprotein was measured by the RT-PCR and Western blot analysis in glioma cells treated with rottlerin. We observed that rottlerin significantly inhibited the expression of Cdc20 in glioma cells, implying that Cdc20 could be a novel target of rottlerin. In line with this, over-expression of Cdc20 decreased rottlerin-induced cell growth inhibition and apoptosis, whereas down-regulation of Cdc20 by its shRNA promotes rottlerin-induced anti-tumor activity. Our findings indicted that rottlerin could exert its tumor suppressive function by inhibiting Cdc20 pathway which is constitutively active in glioma cells. Therefore, down-regulation of Cdc20 by rottlerin could be a promising therapeutic strategy for the treatment of glioma. PMID:27626499

  7. The F-BAR Protein PACSIN2 Regulates Epidermal Growth Factor Receptor Internalization

    PubMed Central

    de Kreuk, Bart-Jan; Anthony, Eloise C.; Geerts, Dirk; Hordijk, Peter L.

    2012-01-01

    Signaling via growth factor receptors, including the epidermal growth factor (EGF) receptor, is key to various cellular processes, such as proliferation, cell survival, and cell migration. In a variety of human diseases such as cancer, aberrant expression and activation of growth factor receptors can lead to disturbed signaling. Intracellular trafficking is crucial for proper signaling of growth factor receptors. As a result, the level of cell surface expression of growth factor receptors is an important determinant for the outcome of downstream signaling. BAR domain-containing proteins represent an important family of proteins that regulate membrane dynamics. In this study, we identify a novel role for the F-BAR protein PACSIN2 in the regulation of EGF receptor signaling. We show that internalized EGF as well as the (activated) EGF receptor translocated to PACSIN2-positive endosomes. Furthermore, loss of PACSIN2 increased plasma membrane expression of the EGF receptor in resting cells and increased EGF-induced phosphorylation of the EGF receptor. As a consequence, EGF-induced activation of Erk and Akt as well as cell proliferation were enhanced in PACSIN2-depleted cells. In conclusion, this study identifies a novel role for the F-BAR-domain protein PACSIN2 in regulating EGF receptor surface levels and EGF-induced downstream signaling. PMID:23129763

  8. Focal adhesion kinase regulates neuronal growth, synaptic plasticity and hippocampus-dependent spatial learning and memory.

    PubMed

    Monje, Francisco J; Kim, Eun-Jung; Pollak, Daniela D; Cabatic, Maureen; Li, Lin; Baston, Arthur; Lubec, Gert

    2012-01-01

    The focal adhesion kinase (FAK) is a non-receptor tyrosine kinase abundantly expressed in the mammalian brain and highly enriched in neuronal growth cones. Inhibitory and facilitatory activities of FAK on neuronal growth have been reported and its role in neuritic outgrowth remains controversial. Unlike other tyrosine kinases, such as the neurotrophin receptors regulating neuronal growth and plasticity, the relevance of FAK for learning and memory in vivo has not been clearly defined yet. A comprehensive study aimed at determining the role of FAK in neuronal growth, neurotransmitter release and synaptic plasticity in hippocampal neurons and in hippocampus-dependent learning and memory was therefore undertaken using the mouse model. Gain- and loss-of-function experiments indicated that FAK is a critical regulator of hippocampal cell morphology. FAK mediated neurotrophin-induced neuritic outgrowth and FAK inhibition affected both miniature excitatory postsynaptic potentials and activity-dependent hippocampal long-term potentiation prompting us to explore the possible role of FAK in spatial learning and memory in vivo. Our data indicate that FAK has a growth-promoting effect, is importantly involved in the regulation of the synaptic function and mediates in vivo hippocampus-dependent spatial learning and memory.

  9. Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts

    SciTech Connect

    DiCicco-Bloom, E.; Black, I.B. )

    1988-06-01

    While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. The authors have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating ({sup 3}H)thymidine into their nuclei. They used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of ({sup 3}H)thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. The observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.

  10. Modification of STIM1 by O-linked N-Acetylglucosamine (O-GlcNAc) Attenuates Store-operated Calcium Entry in Neonatal Cardiomyocytes*

    PubMed Central

    Zhu-Mauldin, Xiaoyuan; Marsh, Susan A.; Zou, Luyun; Marchase, Richard B.; Chatham, John C.

    2012-01-01

    Store-operated calcium entry (SOCE) is a major Ca2+ signaling pathway responsible for regulating numerous transcriptional events. In cardiomyocytes SOCE has been shown to play an important role in regulating hypertrophic signaling pathways, including nuclear translocation of NFAT. Acute activation of pathways leading to O-GlcNAc synthesis have been shown to impair SOCE-mediated transcription and in diabetes, where O-GlcNAc levels are chronically elevated, cardiac hypertrophic signaling is also impaired. Therefore the goal of this study was to determine whether changes in cardiomyocyte O-GlcNAc levels impaired the function of STIM1, a widely recognized mediator of SOCE. We demonstrated that acute activation of SOCE in neonatal cardiomyocytes resulted in STIM1 puncta formation, which was inhibited in a dose-dependent manner by increasing O-GlcNAc synthesis with glucosamine or inhibiting O-GlcNAcase with thiamet-G. Glucosamine and thiamet-G also inhibited SOCE and were associated with increased O-GlcNAc modification of STIM1. These results suggest that activation of cardiomyocyte O-GlcNAcylation attenuates SOCE via STIM1 O-GlcNAcylation and that this may represent a new mechanism by which increased O-GlcNAc levels regulate Ca2+-mediated events in cardiomyocytes. Further, since SOCE is a fundamental mechanism underlying Ca2+ signaling in most cells and tissues, it is possible that STIM1 represents a nexus linking protein O-GlcNAcylation with Ca2+-mediated transcription. PMID:22992728

  11. Laminin-511, inducer of hair growth, is down-regulated and its suppressor in hair growth, laminin-332 up-regulated in chemotherapy-induced alopecia

    PubMed Central

    Imanishi, Hisayoshi; Tsuruta, Daisuke; Tateishi, Chiharu; Sugawara, Koji; Paus, Ralf; Tsuji, Tsutomu; Ishii, Masamitsu; Ikeda, Kazuo; Kunimoto, Hiroyuki; Nakajima, Koichi; Jones, Jonathan C.R.; Kobayashi, Hiromi

    2010-01-01

    Background Chemotherapy-induced alopecia (CIA) has a devastating cosmetic effect, especially in the young. Recent data indicate that two major basement membrane components (laminin-332 and -511) of the skin have opposing effects on hair growth. Objective In this study, we examined the role and localization of laminin-332 and -511 in CIA. Methods We examined the expression of laminin-332 and -511 during the dystrophic catagen form of CIA induced in C57BL/6 mice by cyclophosphamide (CYP) treatment. Results Our data indicate that both laminin-332 and its receptor α6β4 integrin are up-regulated (both quantitatively and spatially) after mid to late dystrophic catagen around the outer root sheath (ORS) in the lower third of hair follicles in CIA. This up-regulation also occurs at the transcriptional level. In contrast, laminin-511 is down-regulated after mid dystrophic catagen at the protein level, with transcriptional inactivation of laminin-511 occurring transiently at the early dystrophic catagen stage in both epidermal and ORS keratinocytes. Laminin-511 expression correlates with expression of α3 integrin in CIA and we also demonstrate that laminin-511 can up-regulate the activity of the α3 integrin promoter in cultured keratinocytes. Injection of a laminin-511 rich protein extract, but not recombinant laminin-332, in the back skin of mice delays hair loss in CYP-induced CIA. Conclusions We propose that abrupt hair loss in CIA is, at least in part, caused by down-regulation of laminin-511 and up-regulation of laminin-332 at the transcriptional and translational levels. PMID:20211547

  12. Regulation of Hepatic Stellate Cells and Fibrogenesis by Fibroblast Growth Factors

    PubMed Central

    2016-01-01

    Fibroblast growth factors (FGFs) are a family of growth factors critically involved in developmental, physiological, and pathological processes, including embryogenesis, angiogenesis, wound healing, and endocrine functions. In the liver, several FGFs are produced basally by hepatocytes and hepatic stellate cells (HSCs). Upon insult to the liver, expression of FGFs in HSCs is greatly upregulated, stimulating hepatocyte regeneration and growth. Various FGF isoforms have also been shown to directly induce HSC proliferation and activation thereby enabling autocrine and paracrine regulation of HSC function. Regulation of HSCs by the endocrine FGFs, namely, FGF15/19 and FGF21, has also recently been identified. With the ability to modulate HSC proliferation and transdifferentiation, targeting FGF signaling pathways constitutes a promising new therapeutic strategy to treat hepatic fibrosis. PMID:27699175

  13. The lure of zebrafish in liver research: regulation of hepatic growth in development and regeneration.

    PubMed

    Cox, Andrew G; Goessling, Wolfram

    2015-06-01

    The liver is an essential organ that plays a pivotal role in metabolism, digestion and nutrient storage. Major efforts have been made to develop zebrafish (Danio rerio) as a model system to study the pathways regulating hepatic growth during liver development and regeneration. Zebrafish offer unique advantages over other vertebrates including in vivo imaging at cellular resolution and the capacity for large-scale chemical and genetic screens. Here, we review the cellular and molecular mechanisms that regulate hepatic growth during liver development in zebrafish. We also highlight emerging evidence that developmental pathways are reactivated following liver injury to facilitate regeneration. Finally, we discuss how zebrafish have transformed drug discovery efforts and enabled the identification of drugs that stimulate hepatic growth and provide hepatoprotection in pre-clinical models of liver injury, with the ultimate goal of identifying novel therapeutic approaches to treat liver disease.

  14. The Ret receptor regulates sensory neuron dendrite growth and integrin mediated adhesion.

    PubMed

    Soba, Peter; Han, Chun; Zheng, Yi; Perea, Daniel; Miguel-Aliaga, Irene; Jan, Lily Yeh; Jan, Yuh Nung

    2015-03-12

    Neurons develop highly stereotyped receptive fields by coordinated growth of their dendrites. Although cell surface cues play a major role in this process, few dendrite specific signals have been identified to date. We conducted an in vivo RNAi screen in Drosophila class IV dendritic arborization (C4da) neurons and identified the conserved Ret receptor, known to play a role in axon guidance, as an important regulator of dendrite development. The loss of Ret results in severe dendrite defects due to loss of extracellular matrix adhesion, thus impairing growth within a 2D plane. We provide evidence that Ret interacts with integrins to regulate dendrite adhesion via rac1. In addition, Ret is required for dendrite stability and normal F-actin distribution suggesting it has an essential role in dendrite maintenance. We propose novel functions for Ret as a regulator in dendrite patterning and adhesion distinct from its role in axon guidance.

  15. Growth factor and co-receptor release by structural regulation of substrate metalloprotease accessibility

    PubMed Central

    Parra, Liseth M.; Hartmann, Monika; Schubach, Salome; Ma, Junzhi; Herrlich, Peter; Herrlich, Andreas

    2016-01-01

    Release of cytokines, growth factors and other life-essential molecules from precursors by a-disintegrin-and-metalloproteases (ADAMs) is regulated with high substrate-specificity. We hypothesized that this is achieved by cleavage-regulatory intracellular-domain (ICD)-modifications of the precursors. We show here that cleavage-stimuli-induced specific ICD-modifications cause structural substrate changes that enhance ectodomain sensitivity of neuregulin-1 (NRG1; epidermal-growth-factor) or CD44 (receptor-tyrosine-kinase (RTK) co-receptor) to chymotrypsin/trypsin or soluble ADAM. This inside-out signal transfer required substrate homodimerization and was prevented by cleavage-inhibitory ICD-mutations. In chimeras, regulation could be conferred to a foreign ectodomain, suggesting a common higher-order structure. We predict that substrate-specific protease-accessibility-regulation controls release of numerous ADAM substrates. PMID:27876763

  16. Cardiomyocyte proliferation in zebrafish and mammals: lessons for human disease.

    PubMed

    Matrone, Gianfranco; Tucker, Carl S; Denvir, Martin A

    2017-04-01

    Cardiomyocytes proliferate profusely during early development and for a brief period after birth in mammals. Within a month after birth, this proliferative capability is dramatically reduced in mammals unlike lower vertebrates where it persists into adult life. The zebrafish, for example, retains the ability to regenerate the apex of the heart following resection by a mechanism predominantly driven by cardiomyocyte proliferation. Differences in proliferative capacity of cardiomyocytes in adulthood between mammals and lower vertebrates are closely liked to ontogenetic or phylogenetic factors. Elucidation of these factors has the potential to provide enormous benefits if they lead to the development of therapeutic strategies that facilitate cardiomyocyte proliferation. In this review, we highlight the differences between Mammalian and Zebrafish cardiomyocytes, which could explain at least in part the different proliferative capacities in these two species. We discuss the advantages of the zebrafish as a model of cardiomyocyte proliferation, particularly at the embryonic stage. We also identify a number of key molecular pathways with potential to reveal key steps in switching cardiomyocytes from a quiescent to a proliferative phenotype.

  17. Recent Insights in the Paracrine Modulation of Cardiomyocyte Contractility by Cardiac Endothelial Cells

    PubMed Central

    Andriantsitohaina, Ramaroson

    2014-01-01

    The cardiac endothelium is formed by a continuous monolayer of cells that line the cavity of the heart (endocardial endothelial cells (EECs)) and the luminal surface of the myocardial blood vessels (intramyocardial capillary endothelial cells (IMCEs)). EECs and IMCEs can exercise substantial control over the contractility of cardiomyocytes by releasing various factors such as nitric oxide (NO) via a constitutive endothelial NO-synthase (eNOS), endothelin-1, prostaglandins, angiotensin II, peptide growth factors, and neuregulin-1. The purpose of the present paper is actually to shortly review recent new information concerning cardiomyocytes as effectors of endothelium paracrine signaling, focusing particularly on contractile function. The modes of action and the regulatory paracrine role of the main mediators delivered by cardiac endothelial cells upon cardiac contractility identified in cardiomyocytes are complex and not fully described. Thus, careful evaluation of new therapeutic approaches is required targeting important physiological signaling pathways, some of which have been until recently considered as deleterious, like reactive oxygen species. Future works in the field of cardiac endothelial cells and cardiac function will help to better understand the implication of these mediators in cardiac physiopathology. PMID:24745027

  18. Differentiation of embryonic stem cells to cardiomyocytes on electrospun nanofibrous substrates.

    PubMed

    Prabhakaran, Molamma P; Mobarakeh, Laleh Ghasemi; Kai, Dan; Karbalaie, Khadijeh; Nasr-Esfahani, Mohammad Hossein; Ramakrishna, Seeram

    2014-04-01

    The potential of pluripotent embryonic stem cells (ESCs) isolated from the inner mass of blastocysts are investigated for its ability to differentiate on biocompatible electrospun nanofibers, for regeneration of the myocardially infracted heart. Nanostructured poly(d,l-lactide-co-glycolide)/collagen (PLGA/Col) scaffolds with fiber diameters in the range of 300 ± 65 nm, was fabricated by electrospinning to mimic the extracellular matrix of the native tissue. During the culture of embryoid bodies outgrowth on the scaffolds, and further differentiation of ESCs to cardiomyocytes, the PLGA/Col nanofibers was found better than that of the electrospun PLGA nanofibers, where a better interaction and growth of ESC differentiated cardiomyocytes was observed on the composite scaffolds. The phenotypical characteristics of ESC-derived cardiomyocytes and molecular protein expression were carried out by scanning electron microscopy and immunocytochemistry, respectively. Our studies highlight the significance of a suitable material, its architecture, and cell-biomaterial interactions that is essential at a nanoscale level signifying the application of a bioengineered cardiac graft for stem cell differentiation and transplantation, which could be an intriguing strategy for cardiac regeneration.

  19. Salicylic Acid Regulates Pollen Tip Growth through an NPR3/NPR4-Independent Pathway.

    PubMed

    Rong, Duoyan; Luo, Nan; Mollet, Jean Claude; Liu, Xuanming; Yang, Zhenbiao

    2016-11-07

    Tip growth is a common strategy for the rapid elongation of cells to forage the environment and/or to target to long-distance destinations. In the model tip growth system of Arabidopsis pollen tubes, several small-molecule hormones regulate their elongation, but how these rapidly diffusing molecules control extremely localized growth remains mysterious. Here we show that the interconvertible salicylic acid (SA) and methylated SA (MeSA), well characterized for their roles in plant defense, oppositely regulate Arabidopsis pollen tip growth with SA being inhibitory and MeSA stimulatory. The effect of SA and MeSA was independent of known NPR3/NPR4 SA receptor-mediated signaling pathways. SA inhibited clathrin-mediated endocytosis in pollen tubes associated with an increased accumulation of less stretchable demethylated pectin in the apical wall, whereas MeSA did the opposite. Furthermore, SA and MeSA alter the apical activation of ROP1 GTPase, a key regulator of tip growth in pollen tubes, in an opposite manner. Interestingly, both MeSA methylesterase and SA methyltransferase, which catalyze the interconversion between SA and MeSA, are localized at the apical region of pollen tubes, indicating of the tip-localized production of SA and MeSA and consistent with their effects on the apical cellular activities. These findings suggest that local generation of a highly diffusible signal can regulate polarized cell growth, providing a novel mechanism of cell polarity control apart from the one involving protein and mRNA polarization.

  20. Methoxychlor inhibits growth of antral follicles by altering cell cycle regulators

    SciTech Connect

    Gupta, Rupesh K. Meachum, Sharon Hernandez-Ochoa, Isabel Peretz, Jackye Yao, Humphrey H. Flaws, Jodi A.

    2009-10-01

    Methoxychlor (MXC) reduces fertility in female rodents, decreases antral follicle numbers, and increases atresia through oxidative stress pathways. MXC also inhibits antral follicle growth in vitro. The mechanism by which MXC inhibits growth of follicles is unknown. The growth of follicles is controlled, in part, by cell cycle regulators. Thus, we tested the hypothesis that MXC inhibits follicle growth by reducing the levels of selected cell cycle regulators. Further, we tested whether co-treatment with an antioxidant, N-acetyl cysteine (NAC), prevents the MXC-induced reduction in cell cycle regulators. For in vivo studies, adult cycling CD-1 mice were dosed with MXC or vehicle for 20 days. Treated ovaries were subjected to immunohistochemistry for proliferating cell nuclear antigen (PCNA) staining. For in vitro studies, antral follicles isolated from adult cycling CD-1 mouse ovaries were cultured with vehicle, MXC, and/or NAC for 48, 72 and 96 h. Levels of cyclin D2 (Ccnd2) and cyclin dependent kinase 4 (Cdk4) were measured using in vivo and in vitro samples. The results indicate that MXC decreased PCNA staining, and Ccnd2 and Cdk4 levels compared to controls. NAC co-treatment restored follicle growth and expression of Ccnd2 and Cdk4. Collectively, these data indicate that MXC exposure reduces the levels of Ccnd2 and Cdk4 in follicles, and that protection from oxidative stress restores Ccnd2 and Cdk4 levels. Therefore, MXC-induced oxidative stress may decrease the levels of cell cycle regulators, which in turn, results in inhibition of the growth of antral follicles.

  1. EPA or DHA supplementation increases triacylglycerol, but not phospholipid, levels in isolated rat cardiomyocytes.

    PubMed

    Righi, Valeria; Di Nunzio, Mattia; Danesi, Francesca; Schenetti, Luisa; Mucci, Adele; Boschetti, Elisa; Biagi, Pierluigi; Bonora, Sergio; Tugnoli, Vitaliano; Bordoni, Alessandra

    2011-07-01

    It is well recognized that a high dietary intake of long-chain polyunsaturated fatty acids (LC-PUFA) has profound benefits on health and prevention of chronic diseases. In particular, in recent years there has been a dramatic surge of interest in the health effects of n-3 LC-PUFA derived from fish, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Notwithstanding, the metabolic fate and the effects of these fatty acids once inside the cell has seldom been comprehensively investigated. Using cultured neonatal rat cardiomyocytes as model system we have investigated for the first time, by means of high-resolution magic-angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy in combination with gas chromatography (GC), the modification occurring in the cell lipid environment after EPA and DHA supplementation. The most important difference between control and n-3 LC-PUFA-supplemented cardiomyocytes highlighted by HR-MAS NMR spectroscopy is the increase of signals from mobile lipids, identified as triacylglycerols (TAG). The observed increase of mobile TAG is a metabolic response to n-3 LC-PUFA supplementation, which leads to an increased lipid storage. The sequestration of mobile lipids in lipid bodies provides a deposit of stored energy that can be accessed in a regulated fashion according to metabolic need. Interestingly, while n-3 LC-PUFA supplementation to neonatal rat cardiomyocytes causes a huge variation in the cell lipid environment, it does not induce detectable modifications in water-soluble metabolites, suggesting negligible interference with normal metabolic processes.

  2. In vivo cardiomyocyte response to YTX- and AZA-1-induced damage: autophagy versus apoptosis.

    PubMed

    Ferreiro, Sara F; Vilariño, Natalia; Carrera, Cristina; Louzao, M Carmen; Santamarina, Germán; Cantalapiedra, Antonio G; Cifuentes, J Manuel; Crespo, Andrés; Botana, Luis M

    2017-04-01

    Yessotoxins (YTX) and azaspiracids (AZAs) are marine toxins produced by phytoplanktonic dinoflagellates that get accumulated in filter feeding shellfish and finally reach human consumers through the food web. Both toxin classes are worldwide distributed, and food safety authorities have regulated their content in shellfish in many countries. Recently, YTXs and AZAs have been described as compounds with subacute cardiotoxic potential in rats owed to alterations of the cardiovascular function and ultrastructural heart damage. These molecules are also well known in vitro inducers of cell death. The aim of this study was to explore the presence of cardiomyocyte death after repeated subacute exposure of rats to AZA-1 and YTX for 15 days. Because autophagy and apoptosis are often found in dying cardiomyocytes, several autophagic and apoptotic markers were determined by western blot in heart tissues of these rats. The results showed that hearts from YTX-treated rats presented increased levels of the autophagic markers microtubule-associated protein light chain 3-II (LC3-II) and beclin-1, nevertheless AZA-1-treated hearts evidenced increased levels of the apoptosis markers cleaved caspase-3 and -8, cleaved PARP and Fas ligand. Therefore, while YTX-induced damage to the heart triggers autophagic processes, apoptosis activation occurs in the case of AZA-1. For the first time, activation of cell death signals in cardiomyocytes is demonstrated for these toxins with in vivo experiments, which may be related to alterations of the cardiovascular function.

  3. Cardiomyocyte behavior on biodegradable polyurethane/gold nanocomposite scaffolds under electrical stimulation.

    PubMed

    Ganji, Yasaman; Li, Qian; Quabius, Elgar Susanne; Böttner, Martina; Selhuber-Unkel, Christine; Kasra, Mehran

    2016-02-01

    Following a myocardial infarction (MI), cardiomyocytes are replaced by scar tissue, which decreases ventricular contractile function. Tissue engineering is a promising approach to regenerate such damaged cardiomyocyte tissue. Engineered cardiac patches can be fabricated by seeding a high density of cardiac cells onto a synthetic or natural porous polymer. In this study, nanocomposite scaffolds made of gold nanotubes/nanowires incorporated into biodegradable castor oil-based polyurethane were employed to make micro-porous scaffolds. H9C2 cardiomyocyte cells were cultured on the scaffolds for one day, and electrical stimulation was applied to improve cell communication and interaction in neighboring pores. Cells on scaffolds were examined by fluorescence microscopy and scanning electron microscopy, revealing that the combination of scaffold design and electrical stimulation significantly increased cell confluency of H9C2 cells on the scaffolds. Furthermore, we showed that the gene expression levels of Nkx2.5, atrial natriuretic peptide (ANF) and natriuretic peptide precursor B (NPPB), which are functional genes of the myocardium, were up-regulated by the incorporation of gold nanotubes/nanowires into the polyurethane scaffolds, in particular after electrical stimulation.

  4. Soybean Homologs of MPK4 Negatively Regulate Defense Responses and Positively Regulate Growth and Development1[W][OA

    PubMed Central

    Liu, Jian-Zhong; Horstman, Heidi D.; Braun, Edward; Graham, Michelle A.; Zhang, Chunquan; Navarre, Duroy; Qiu, Wen-Li; Lee, Yeunsook; Nettleton, Dan; Hill, John H.; Whitham, Steven A.

    2011-01-01

    Mitogen-activated protein kinase (MAPK) cascades play important roles in disease resistance in model plant species such as Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum). However, the importance of MAPK signaling pathways in the disease resistance of crops is still largely uninvestigated. To better understand the role of MAPK signaling pathways in disease resistance in soybean (Glycine max), 13, nine, and 10 genes encoding distinct MAPKs, MAPKKs, and MAPKKKs, respectively, were silenced using virus-induced gene silencing mediated by Bean pod mottle virus. Among the plants silenced for various MAPKs, MAPKKs, and MAPKKKs, those in which GmMAPK4 homologs (GmMPK4s) were silenced displayed strong phenotypes including stunted stature and spontaneous cell death on the leaves and stems, the characteristic hallmarks of activated defense responses. Microarray analysis showed that genes involved in defense responses, such as those in salicylic acid (SA) signaling pathways, were significantly up-regulated in GmMPK4-silenced plants, whereas genes involved in growth and development, such as those in auxin signaling pathways and in cell cycle and proliferation, were significantly down-regulated. As expected, SA and hydrogen peroxide accumulation was significantly increased in GmMPK4-silenced plants. Accordingly, GmMPK4-silenced plants were more resistant to downy mildew and Soybean mosaic virus compared with vector control plants. Using bimolecular fluorescence complementation analysis and in vitro kinase assays, we determined that GmMKK1 and GmMKK2 might function upstream of GmMPK4. Taken together, our results indicate that GmMPK4s negatively regulate SA accumulation and defense response but positively regulate plant growth and development, and their functions are conserved across plant species. PMID:21878550

  5. Placental insufficiency decreases cell cycle activity and terminal maturation in fetal sheep cardiomyocytes

    PubMed Central

    Louey, Samantha; Jonker, Sonnet S; Giraud, George D; Thornburg, Kent L

    2007-01-01

    Umbilicoplacental embolization (UPE) in sheep has been used to investigate the effects of placental insufficiency on fetal development. However, its specific effects on the heart have been little studied. The aim of this study was to determine the effects of placental insufficiency, induced by UPE, on cardiomyocyte size, maturation and proliferation. Instrumented fetal sheep underwent UPE for either 10 or 20 days. Hearts were collected at 125 ± 1 days (10 day group) or 136 ± 1 days (20 day group) of gestation (term ∼145 days). Cell size, maturational state (as measured by the proportion of binucleated myocytes) and cell cycle activity (as measured by positive staining of cells for Ki-67) were determined in dissociated cardiomyocytes. UPE fetuses were hypoxaemic, but mean arterial pressures were not different from controls. UPE fetuses were lighter than control fetuses (10 days: −21%, P < 0.05; 20 days: −27%, P < 0.01) and had smaller hearts, but heart weight was appropriate for body weight. Neither lengths nor widths were different between control and UPE cardiomyocytes at either age. Ten days of UPE did not significantly alter the proportion of binucleated myocytes or cell cycle activity in either ventricle. However, 20 days of UPE reduced cell cycle activity in both ventricles by ∼70% (P < 0.05); the proportion of binucleated myocytes was also lower in UPE fetuses at this age (left ventricle: 31.1 ± 12.0 versus 46.0 ± 6.6%, P < 0.05; right ventricle: 29.4 ± 12.3 versus 46.3 ± 5.3%, P < 0.05). It is concluded that in the absence of fetal arterial hypertension, placental insufficiency is associated with substantially depressed growth of the heart through suppressed proliferation and maturation of cardiomyocytes. PMID:17234700

  6. Regulation of vascular endothelial growth factor secretion in human meningioma cells.

    PubMed

    Tsai, J C; Hsiao, Y Y; Teng, L J; Shun, C T; Chen, C T; Goldman, C K; Kao, M C

    1999-02-01

    Previously, we induced vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) secretion in glioma cell lines by using physiologic concentrations of epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), or platelet-derived growth factor-BB (PDGF-BB). We hypothesized that VEGF/VPF might enhance the blood supply required for the unregulated growth of tumors, and that it acts as the central mediator of tumor angiogenesis. The objective of this study was to determine whether the expression of VEGF/VPF by meningiomas is regulated by growth factors or sex hormones. By means of an enzyme-linked immunosorbent assay of CH-157MN meningioma cell supernatants, we demonstrated that EGF and bFGF similarly induce VEGF secretion by CH-157MN meningioma cells. At the maximum concentrations of EGF (50 ng/mL) and bFGF (50 ng/mL) used in this study, VEGF secretion was induced to 140% to 160% above baseline constitutive secretion. PDGF-BB homodimer did not enhance VEGF secretion significantly. Estradiol (up to 10(-7) mol/L), progesterone (up to 10(-5) mol/L), or testosterone (up to 10(-5) mol/L) did not stimulate or inhibit VEGF secretion in CH-157MN meningioma cells (p > 0.05). Furthermore, we demonstrated that dexamethasone decreased VEGF secretion to 32% of baseline constitutive secretion. This might explain the effect of corticosteroids in alleviating peritumoral brain edema in meningiomas. These results suggest that VEGF secretion in CH-157MN meningioma cells is mainly regulated by growth factors and corticosteroids, but not by sex hormones. Understanding the regulation of VEGF/VPF secretion in meningiomas might contribute to the development of a new therapeutic strategy.

  7. MicroRNA-145 suppresses ROS-induced Ca{sup 2+} overload of cardiomyocytes by targeting CaMKIIδ

    SciTech Connect

    Cha, Min-Ji; Jang, Jin-Kyung; Ham, Onju; Song, Byeong-Wook; Lee, Se-Yeon; Lee, Chang Yeon; Park, Jun-Hee; Lee, Jiyun; Seo, Hyang-Hee; Choi, Eunhyun; Jeon, Woo-min; Hwang, Hye Jin; Shin, Hyun-Taek; and others

    2013-06-14

    Highlights: •CaMKIIδ mediates H{sub 2}O{sub 2}-induced Ca{sup 2+} overload in cardiomyocytes. •miR-145 can inhibit Ca{sup 2+} overload. •A luciferase assay confirms that miR-145 functions as a CaMKIIδ-targeting miRNA. •Overexpression of miR-145 regulates CaMKIIδ-related genes and ameliorates apoptosis. -- Abstract: A change in intracellular free calcium (Ca{sup 2+}) is a common signaling mechanism of reperfusion-induced cardiomyocyte death. Calcium/calmodulin dependent protein kinase II (CaMKII) is a critical regulator of Ca{sup 2+} signaling and mediates signaling pathways responsible for functions in the heart including hypertrophy, apoptosis, arrhythmia, and heart disease. MicroRNAs (miRNA) are involved in the regulation of cell response, including survival, proliferation, apoptosis, and development. However, the roles of miRNAs in Ca{sup 2+}-mediated apoptosis of cardiomyocytes are uncertain. Here, we determined the potential role of miRNA in the regulation of CaMKII dependent apoptosis and explored its underlying mechanism. To determine the potential roles of miRNAs in H{sub 2}O{sub 2}-mediated Ca{sup 2+} overload, we selected and tested 6 putative miRNAs that targeted CaMKIIδ, and showed that miR-145 represses CaMKIIδ protein expression and Ca{sup 2+} overload. We confirmed CaMKIIδ as a direct downstream target of miR-145. Furthermore, miR-145 regulates Ca{sup 2+}-related signals and ameliorates apoptosis. This study demonstrates that miR-145 regulates reactive oxygen species (ROS)-induced Ca{sup 2+} overload in cardiomyocytes. Thus, miR-145 affects ROS-mediated gene regulation and cellular injury responses.

  8. Stiff Mutant Genes of Phycomyces Affect Turgor Pressure and Wall Mechanical Properties to Regulate Elongation Growth Rate

    PubMed Central

    Ortega, Joseph K. E.; Munoz, Cindy M.; Blakley, Scott E.; Truong, Jason T.; Ortega, Elena L.

    2012-01-01

    Regulation of cell growth is paramount to all living organisms. In plants, algae and fungi, regulation of expansive growth of cells is required for development and morphogenesis. Also, many sensory responses of stage IVb sporangiophores of Phycomyces blakesleeanus are produced by regulating elongation growth rate (growth responses) and differential elongation growth rate (tropic responses). “Stiff” mutant sporangiophores exhibit diminished tropic responses and are found to be defective in at least five genes; madD, E, F, G, and J. Prior experimental research suggests that the defective genes affect growth regulation, but this was not verified. All the growth of the single-celled stalk of the stage IVb sporangiophore occurs in a short region termed the “growth zone.” Prior experimental and theoretical research indicates that elongation growth rate of the stage IVb sporangiophore can be regulated by controlling the cell wall mechanical properties within the growth zone and the magnitude of the turgor pressure. A quantitative biophysical model for elongation growth rate is required to elucidate the relationship between wall mechanical properties and turgor pressure during growth regulation. In this study, it is hypothesized that the mechanical properties of the wall within the growth zone of stiff mutant sporangiophores are different compared to wild type (WT). A biophysical equation for elongation growth rate is derived for fungal and plant cells with a growth zone. Two strains of stiff mutants are studied, C149 madD120 (−) and C216 geo- (−). Experimental results demonstrate that turgor pressure is larger but irreversible wall deformation rates within the growth zone and growth zone length are smaller for stiff mutant sporangiophores compared to WT. These findings can explain the diminished tropic responses of the stiff mutant sporangiophores. It is speculated that the defective genes affect the amount of wall-building material delivered to the inner cell

  9. Stiff mutant genes of phycomyces affect turgor pressure and wall mechanical properties to regulate elongation growth rate.

    PubMed

    Ortega, Joseph K E; Munoz, Cindy M; Blakley, Scott E; Truong, Jason T; Ortega, Elena L

    2012-01-01

    Regulation of cell growth is paramount to all living organisms. In plants, algae and fungi, regulation of expansive growth of cells is required for development and morphogenesis. Also, many sensory responses of stage IVb sporangiophores of Phycomyces blakesleeanus are produced by regulating elongation growth rate (growth responses) and differential elongation growth rate (tropic responses). "Stiff" mutant sporangiophores exhibit diminished tropic responses and are found to be defective in at least five genes; madD, E, F, G, and J. Prior experimental research suggests that the defective genes affect growth regulation, but this was not verified. All the growth of the single-celled stalk of the stage IVb sporangiophore occurs in a short region termed the "growth zone." Prior experimental and theoretical research indicates that elongation growth rate of the stage IVb sporangiophore can be regulated by controlling the cell wall mechanical properties within the growth zone and the magnitude of the turgor pressure. A quantitative biophysical model for elongation growth rate is required to elucidate the relationship between wall mechanical properties and turgor pressure during growth regulation. In this study, it is hypothesized that the mechanical properties of the wall within the growth zone of stiff mutant sporangiophores are different compared to wild type (WT). A biophysical equation for elongation growth rate is derived for fungal and plant cells with a growth zone. Two strains of stiff mutants are studied, C149 madD120 (-) and C216 geo- (-). Experimental results demonstrate that turgor pressure is larger but irreversible wall deformation rates within the growth zone and growth zone length are smaller for stiff mutant sporangiophores compared to WT. These findings can explain the diminished tropic responses of the stiff mutant sporangiophores. It is speculated that the defective genes affect the amount of wall-building material delivered to the inner cell wall.

  10. On the Role of Abscisic Acid and Gibberellin in the Regulation of Growth in Rice 1

    PubMed Central

    Hoffmann-Benning, Susanne; Kende, Hans

    1992-01-01

    Submergence induces rapid elongation of rice coleoptiles (Oryza sativa L.) and of deepwater rice internodes. This adaptive feature helps rice to grow out of the water and to survive flooding. Earlier, we found that the growth response of submerged deepwater rice plants is mediated by ethylene and gibberellin (GA). Ethylene promotes growth, at least in part, by increasing the responsiveness of the internodal tissue to GA. In the present work, we examined the possibility that increased responsiveness to GA was based on a reduction in endogenous abscisic acid (ABA) levels. Submergence and treatment with ethylene led, within 3 hours, to a 75% reduction in the level of ABA in the intercalary meristem and the growing zone of deepwater rice internodes. The level of GA1 increased fourfold during the same time period. An interaction between GA and ABA could also be shown by application of the hormones. ABA inhibited growth of submerged internodes, and GA counteracted this inhibition. Our results indicate that the growth rate of deepwater rice internodes is determined by the ratio of an endogenous growth promoter (GA) and a growth inhibitor (ABA). We also investigated whether ABA is involved in regulating the growth of rice coleoptiles. Rice seedlings were grown on solutions containing fluridone, an inhibitor of carotenoid and, indirectly, of ABA biosynthesis. Treatment with fluridone reduced the level of ABA in coleoptiles and first leaves by more than 75% and promoted coleoptile growth by more than 60%. Little or no enhancement of growth by fluridone was observed in barley, oat, or wheat. The involvement of ABA in determining the growth rate of rice coleoptiles and deepwater rice internodes may be related to the semiaquatic growth habit of this plant. PMID:16668983

  11. Quantitative Non-canonical Amino Acid Tagging (QuaNCAT) Proteomics Identifies Distinct Patterns of Protein Synthesis Rapidly Induced by Hypertrophic Agents in Cardiomyocytes, Revealing New Aspects of Metabolic Remodeling*

    PubMed Central

    Liu, Rui; Kenney, Justin W.; Manousopoulou, Antigoni; Johnston, Harvey E.; Kamei, Makoto; Woelk, Christopher H.; Xie, Jianling; Schwarzer, Michael; Proud, Christopher G.

    2016-01-01

    Cardiomyocytes undergo growth and remodeling in response to specific pathological or physiological conditions. In the former, myocardial growth is a risk factor for cardiac failure and faster protein synthesis is a major factor driving cardiomyocyte growth. Our goal was to quantify the rapid effects of different pro-hypertrophic stimuli on the synthesis of specific proteins in ARVC and to determine whether such effects are caused by alterations on mRNA abundance or the translation of specific mRNAs. Cardiomyocytes have very low rates of protein synthesis, posing a challenging problem in terms of studying changes in the synthesis of specific proteins, which also applies to other nondividing primary cells. To study the rates of accumulation of specific proteins in these cells, we developed an optimized version of the Quantitative Noncanonical Amino acid Tagging LC/MS proteomic method to label and selectively enrich newly synthesized proteins in these primary cells while eliminating the suppressive effects of pre-existing and highly abundant nonisotope-tagged polypeptides. Our data revealed that a classical pathologic (phenylephrine; PE) and the recently identified insulin stimulus that also contributes to the development of pathological cardiac hypertrophy (insulin), both increased the synthesis of proteins involved in, e.g. glycolysis, the Krebs cycle and beta-oxidation, and sarcomeric components. However, insulin increased synthesis of many metabolic enzymes to a greater extent than PE. Using a novel validation method, we confirmed that synthesis of selected candidates is indeed up-regulated by PE and insulin. Synthesis of all proteins studied was up-regulated by signaling through mammalian target of rapamycin complex 1 without changes in their mRNA levels, showing the key importance of translational control in the rapid effects of hypertrophic stimuli. Expression of PKM2 was up-regulated in rat hearts following TAC. This isoform possesses specific regulatory

  12. Effect of Three Statins on Glucose Uptake of Cardiomyocytes and its Mechanism

    PubMed Central

    Jiang, Zhenhuan; Yu, Bo; Li, Yang

    2016-01-01

    Background The aim of this study was to investigate the effects of different statins on glucose uptake and to confirm its mechanism in primary cultured rat cardiomyocytes after administration of atorvastatin, pravastatin, and rosuvastatin. Material/Methods Primary cultured rat cardiomyocytes were randomly assigned to 5 groups: normal control group (OB), insulin group (S1), statin 1-μM (S2), 5-μM (S3), and 10-μM (S4) groups for 3 different statins. The 2-[3H]-DG uptake of each group was determined and the mRNA and protein expression levels of glucose transporter type 4 (GLUT4), insulin receptor substrate (IRs), and RhoA were assessed. Results After treatment with different concentrations of statins and insulin, the 2-[3H]-DG uptake showed a significant negative correlation with the concentration of atorvastatin (P<0.05), and no significant correlation with pravastatin and rosuvastatin. The mRNA and protein expression levels of GLUT4 and IRs-1 in primary cultured cardiomyocytes were both significantly reduced by atorvastatin treatment (P<0.05). Pravastatin and rosuvastatin showed no significant effects on GLUT4 and IRs-1 expression. The mRNA and protein expression levels of RhoA both showed no significant difference when treated with the 3 statins. Conclusions These results confirm that atorvastatin can inhibit insulin-induced glucose uptake in primary cultured rat cardiomyocytes by regulating the PI3K/Akt insulin signal transduction pathway. PMID:27510725

  13. Sevoflurane postconditioning attenuates cardiomyocyte hypoxia/reoxygenation injury via restoring mitochondrial morphology

    PubMed Central

    Yu, Jin; Wu, Jianjiang; Xie, Peng; Maimaitili, Yiliyaer; Wang, Jiang; Xia, Zhengyuan; Gao, Feng; Zhang, Xing

    2016-01-01

    Background Anesthetic postconditioning is a cellular protective approach whereby exposure to a volatile anesthetic renders a tissue more resistant to subsequent ischemic/reperfusion event. Sevoflurane postconditioning (SPostC) has been shown to exert cardioprotection against ischemia/reperfusion injury, but the underlying mechanism is unclear. We hypothesized that SPostC protects cardiomyocytes against hypoxia/reoxygenation (H/R) injury by maintaining/restoring mitochondrial morphological integrity, a critical determinant of cell fate. Methods Primary cultures of neonatal rat cardiomyocytes (NCMs) were subjected to H/R injury (3 h of hypoxia followed by 3 h reoxygenation). Intervention with SPostC (2.4% sevoflurane) was administered for 15 min upon the onset of reoxygenation. Cell viability, Lactate dehydrogenase (LDH) level, cell death, mitochondrial morphology, mitochondrial membrane potential and mitochondrial permeability transition pore (mPTP) opening were assessed after intervention. Mitochondrial fusion and fission regulating proteins (Drp1, Fis1, Mfn1, Mfn2 and Opa1) were assessed by immunofluorescence staining and western blotting was performed to determine the level of protein expression. Results Cardiomyocyte H/R injury resulted in significant increases in LDH release and cell death that were concomitant with reduced cell viability and reduced mitochondrial interconnectivity (mean area/perimeter ratio) and mitochondrial elongation, and with reduced mitochondrial membrane potential and increased mPTP opening. All the above changes were significantly attenuated by SPostC. Furthermore, H/R resulted in significant reductions in mitochondrial fusion proteins Mfn1, Mfn2 and Opa1 and significant enhancement of fission proteins Drp1 and Fis1. SPostC significantly enhanced Mfn2 and Opa1 and reduced Drp1, without significant impact on Mfn1 and Fis1. Conclusions Sevoflurane postconditioning attenuates cardiomyocytes hypoxia/reoxygenation injury (HRI) by restoring

  14. Heme-induced contractile dysfunction in human cardiomyocytes caused by oxidant damage to thick filament proteins.

    PubMed

    Alvarado, Gerardo; Jeney, Viktória; Tóth, Attila; Csősz, Éva; Kalló, Gergő; Huynh, An T; Hajnal, Csaba; Kalász, Judit; Pásztor, Enikő T; Édes, István; Gram, Magnus; Akerström, Bo; Smith, Ann; Eaton, John W; Balla, György; Papp, Zoltán; Balla, József

    2015-12-01

    Intracellular free heme predisposes to oxidant-mediated tissue damage. We hypothesized that free heme causes alterations in myocardial contractility via disturbed structure and/or regulation of the contractile proteins. Isometric force production and its Ca(2+)-sensitivity (pCa50) were monitored in permeabilized human ventricular cardiomyocytes. Heme exposure altered cardiomyocyte morphology and evoked robust decreases in Ca(2+)-activated maximal active force (Fo) while increasing Ca(2+)-independent passive force (F passive). Heme treatments, either alone or in combination with H2O2, did not affect pCa50. The increase in F passive started at 3 µM heme exposure and could be partially reversed by the antioxidant dithiothreitol. Protein sulfhydryl (SH) groups of thick myofilament content decreased and sulfenic acid formation increased after treatment with heme. Partial restoration in the SH group content was observed in a protein running at 140 kDa after treatment with dithiothreitol, but not in other proteins, such as filamin C, myosin heavy chain, cardiac myosin binding protein C, and α-actinin. Importantly, binding of heme to hemopexin or alpha-1-microglobulin prevented its effects on cardiomyocyte contractility, suggesting an allosteric effect. In line with this, free heme directly bound to myosin light chain 1 in human cardiomyocytes. Our observations suggest that free heme modifies cardiac contractile proteins via posttranslational protein modifications and via binding to myosin light chain 1, leading to severe contractile dysfunction. This may contribute to systolic and diastolic cardiac dysfunctions in hemolytic diseases, heart failure, and myocardial ischemia-reperfusion injury.

  15. A piezoelectric electrospun platform for in situ cardiomyocyte contraction analysis

    NASA Astrophysics Data System (ADS)

    Beringer, Laura Toth

    hyperpolarized state, proving their potential use as contractile analysis microdevices. The third and final aim of this dissertation was to be able to measure contraction events from both cultured cardiomyocytes and whole tissues in situ. Rat neonatal cardiomyocytes grew on the prepared collagen/PVDF-TrFe nanogenerators and yielded a distinct signal after 8 days of growth. These contractions were verified with live cell imaging and video recording. In addition, cardiomyocyte exposure to the drug isoproterenol increased contraction strength and frequency, which was reflected in the nanogenerator recordings. Frog whole heart and heart tissue slices also were interfaced with the fabricated nanogenerators and signals were recorded. The same held true for heart slices from male Sprague-Dawley rats. These signals were determined to be statistically different compared to the control baseline nanogenerator recordings in media in the absence of cell culture. Overall the fabricated nanogenerators have demonstrated their potential to be used as in situ analysis tools for contractile events and have potential in the field of personalized medicine and drug diagnostic assays. The facile fabrication and ease of setup to obtain the electrical voltage signal corresponding to the contractile events are what sets the nanogenerator apart from any polymer based sensor available today.

  16. Glutamine metabolism links growth factor signaling to the regulation of autophagy.

    PubMed

    van der Vos, Kristan E; Coffer, Paul J

    2012-12-01

    Activation of the PI3K-AKT1-FOXO module by growth factors increases survival and stress resistance. We identified the gene encoding glutamine synthetase (GLUL, glutamate-ammonia ligase) as a novel transcriptional target of this signaling cascade. Growth factor removal increases glutamine synthetase expression and activity through activation of FOXO transcription factors. Surprisingly, increased levels of glutamine synthetase inhibit MTOR signaling by blocking its lysosomal translocation. Furthermore, FOXO activation induces autophagosome formation and autophagic flux in a glutamine synthetase-dependent manner. This may be important for maintaining cell survival during conditions of growth factor and nutrient deprivation since inhibition of autophagy induces cell death. These studies reveal that glutamine metabolism can play an important regulatory role in the regulation of autophagy by growth factor signaling. In addition, the induction of autophagy by FOXO-mediated glutamine synthetase expression might contribute to the tumor suppressive function of FOXOs.

  17. In situ growth of juvenile zebra mussels in a regulated stream

    USGS Publications Warehouse

    French, John R. P.; Nichols, S. Jerrine; Craig, Jaquelyn M.; Allen, Jeffery D.; Black, M. Glen

    2006-01-01

    We investigated the in situ growth of juvenile zebra mussels (Dreissena polymorpha) in a reach of the Huron River (southeast Michigan) below a dam with a control gate that regulates water levels. Growth was significantly different among sample dates over a five-month-long monitoring season. Mean growth of mussels generally decreased from 0.093 mm/day just above the dam to 0.067 mm/day 4 km downstream, then increased to 0.091 mm/day at end of the 17-km-long study area. Significant differences among sites were most numerous in August during a severe drought when discharges fell substantially. Growth was positively correlated with discharges (R2 = 0.94, p a levels in the study area, however, was weak (R2 = 0.69, p < 0.1). Our study suggests that discharge may be one controlling factor for dreissenid populations in small streams.

  18. The Nuclear Receptor DAF-12 Regulates Nutrient Metabolism and Reproductive Growth in Nematodes

    PubMed Central

    Wang, Zhu; Stoltzfus, Jonathan; You, Young-jai; Ranjit, Najju; Tang, Hao; Xie, Yang; Lok, James B.; Mangelsdorf, David J.; Kliewer, Steven A.

    2015-01-01

    Appropriate nutrient response is essential for growth and reproduction. Under favorable nutrient conditions, the C. elegans nuclear receptor DAF-12 is activated by dafachronic acids, hormones that commit larvae to reproductive growth. Here, we report that in addition to its well-studied role in controlling developmental gene expression, the DAF-12 endocrine system governs expression of a gene network that stimulates the aerobic catabolism of fatty acids. Thus, activation of the DAF-12 transcriptome coordinately mobilizes energy stores to permit reproductive growth. DAF-12 regulation of this metabolic gene network is conserved in the human parasite, Strongyloides stercoralis, and inhibition of specific steps in this network blocks reproductive growth in both of the nematodes. Our study provides a molecular understanding for metabolic adaptation of nematodes to their environment, and suggests a new therapeutic strategy for treating parasitic diseases. PMID:25774872

  19. Growth control in colon epithelial cells: gadolinium enhances calcium-mediated growth regulation.

    PubMed

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K; Varani, James

    2012-12-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1-5 μM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet.

  20. Caveolin-1 is down-regulated in alveolar rhabdomyosarcomas and negatively regulates tumor growth

    PubMed Central

    Huertas-Martínez, Juan; Rello-Varona, Santiago; Herrero-Martín, David; Barrau, Ignasi; García-Monclús, Silvia; Sáinz-Jaspeado, Miguel; Lagares-Tena, Laura; Núñez-Álvarez, Yaiza; Mateo-Lozano, Silvia; Mora, Jaume; Roma, Josep; Toran, Nuria; Moran, Sebastian; López-Alemany, Roser; Gallego, Soledad; Esteller, Manel; Peinado, Miguel A.; Xavier García del, Muro; Tirado, Oscar M.

    2014-01-01

    Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence. Despite advances in therapy, patients with histological variant of rhabdomyosarcoma known as alveolar rhabdomyosarcoma (ARMS) have a 5-year survival of less than 30%. Caveolin-1 (CAV1), encoding the structural component of cellular caveolae, is a suggested tumor suppressor gene involved in cell signaling. In the present study we report that compared to other forms of rhabdomyosarcoma (RMS) CAV1 expression is either undetectable or very low in ARMS cell lines and tumor samples. DNA methylation analysis of the promoter region and azacytidine-induced re-expression suggest the involvement of epigenetic mechanisms in the silencing of CAV1. Reintroduction of CAV1 in three of these cell lines impairs their clonogenic capacity and promotes features of muscular differentiation. In vitro, CAV1-expressing cells show high expression of Caveolin-3 (CAV3), a muscular differentiation marker. Blockade of MAPK signaling is also observed. In vivo, CAV1-expressing xenografts show growth delay, features of muscular differentiation and increased cell death. In summary, our results suggest that CAV1 could function as a potent tumor suppressor in ARMS tumors. Inhibition of CAV1 function therefore, could contribute to aberrant cell proliferation, leading to ARMS development. PMID:25313138

  1. Growth rate regulation of translation initiation factor IF3 biosynthesis in Escherichia coli.

    PubMed Central

    Liveris, D; Klotsky, R A; Schwartz, I

    1991-01-01

    infC, the gene encoding translation initiation factor IF3 in Escherichia coli, can be transcribed from three promoters. Two of these promoters, PI1 and PI2, are located in the upstream thrS sequence which codes for threonyl-tRNA synthetase. Previous studies had shown that PI2 was the major promoter for infC. In the present study, the extent of transcription from PI1 and/or PI2 at a variety of steady-state growth rates was analyzed by promoter fusion studies. PI2 was the more active promoter (two- to threefold stronger than PI1) at all growth rates tested. A fusion plasmid containing both PI1 and PI2 exhibited a transcription level approximately equal to the sum of those observed with the fusion plasmids containing the individual promoters. The transcriptional activities of PI1 and PI2 did not change as the growth rate was varied from 0.3 to 1.7 doublings per h. In contrast, a fusion plasmid carrying the rrnB P1 promoter displayed the expected growth rate response. The steady-state concentrations of infC mRNA in cells grown at different rates were measured and found not to vary. These results indicate that the previously reported growth rate regulation of IF3 biosynthesis neither is accomplished by transcriptional control nor is a result of differential mRNA stability. In view of these results, the steady-state levels of IF3 in cells grown at a number of different growth rates were determined by quantitative immunoblotting. IF3 levels were found to vary with growth rate in a manner essentially identical to that observed for ribosomes. A model accounting for these results and describing a mechanism for coordinate growth rate-regulated expression of ribosomes and IF3 is presented. Images PMID:2050639

  2. Ohgata, the Single Drosophila Ortholog of Human Cereblon, Regulates Insulin Signaling-dependent Organismic Growth.

    PubMed

    Wakabayashi, Satoru; Sawamura, Naoya; Voelzmann, André; Broemer, Meike; Asahi, Toru; Hoch, Michael

    2016-11-25

    Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that is highly conserved in animals and plants. CRBN proteins have been implicated in various biological processes such as development, metabolism, learning, and memory formation, and their impairment has been linked to autosomal recessive non-syndromic intellectual disability and cancer. Furthermore, human CRBN was identified as the primary target of thalidomide teratogenicity. Data on functional analysis of CRBN family members in vivo, however, are still scarce. Here we identify Ohgata (OHGT), the Drosophila ortholog of CRBN, as a regulator of insulin signaling-mediated growth. Using ohgt mutants that we generated by targeted mutagenesis, we show that its loss results in increased body weight and organ size without changes of the body proportions. We demonstrate that ohgt knockdown in the fat body, an organ analogous to mammalian liver and adipose tissue, phenocopies the growth phenotypes. We further show that overgrowth is due to an elevation of insulin signaling in ohgt mutants and to the down-regulation of inhibitory cofactors of circulating Drosophila insulin-like peptides (DILPs), named acid-labile subunit and imaginal morphogenesis protein-late 2. The two inhibitory proteins were previously shown to be components of a heterotrimeric complex with growth-promoting DILP2 and DILP5. Our study reveals OHGT as a novel regulator of insulin-dependent organismic growth in Drosophila.

  3. Integrating the immune system with the regulation of growth and efficiency.

    PubMed

    Gabler, N K; Spurlock, M E

    2008-04-01

    Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Recent evidence indicates that adipocytes and myofibers are equipped with functional pattern recognition receptors and are capable of responding directly to the corresponding pathogens and other receptor ligands. Thus, these cells are active participants in the innate immune response and, as such, produce a number of immune and metabolic regulators, including proinflammatory cytokines and adiponectin. Specifically, the transcription factor, nuclear factor kappa B, is activated in adipocytes and muscle cells by bacterial lipopolysaccharide and certain saturated fatty acids, which are potent agonists for the Toll-like receptor-4 pattern recognition receptor. Receptor activation results in the local production of interleukin-6 and tumor necrosis factor-alpha, and creates a local environment by which these cytokines regulate both metabolic and immunological pathways. However, adipocytes are also the predominant source of the antiinflammatory hormone, adiponectin, which suppresses the activation of nuclear factor kappa B and the production of proinflammatory cytokines. The molecular ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally and to reciprocally regulate metabolism in peripheral tissues.

  4. Prioritizing plant defence over growth through WRKY regulation facilitates infestation by non-target herbivores

    PubMed Central

    Li, Ran; Zhang, Jin; Li, Jiancai; Zhou, Guoxin; Wang, Qi; Bian, Wenbo; Erb, Matthias; Lou, Yonggen

    2015-01-01

    Plants generally respond to herbivore attack by increasing resistance and decreasing growth. This prioritization is achieved through the regulation of phytohormonal signaling networks. However, it remains unknown how this prioritization affects resistance against non-target herbivores. In this study, we identify WRKY70 as a specific herbivore-induced, mitogen-activated protein kinase-regulated rice transcription factor that physically interacts with W-box motifs and prioritizes defence over growth by positively regulating jasmonic acid (JA) and negatively regulating gibberellin (GA) biosynthesis upon attack by the chewing herbivore Chilo suppressalis. WRKY70-dependent JA biosynthesis is required for proteinase inhibitor activation and resistance against C. suppressalis. In contrast, WRKY70 induction increases plant susceptibility against the rice brown planthopper Nilaparvata lugens. Experiments with GA-deficient rice lines identify WRKY70-dependent GA signaling as the causal factor in N. lugens susceptibility. Our study shows that prioritizing defence over growth leads to a significant resistance trade-off with important implications for the evolution and agricultural exploitation of plant immunity. DOI: http://dx.doi.org/10.7554/eLife.04805.001 PMID:26083713

  5. Merlin inhibits growth hormone-regulated Raf-ERKs pathways by binding to Grb2 protein

    SciTech Connect

    Lim, Jung Yeon; Kim, Hongtae; Jeun, Sin-Soo . E-mail: ssjeun@catholic.ac.kr; Kang, Seok-Gu; Lee, Kyung-Jin

    2006-02-24

    Numerous studies have suggested that the NF2 protein merlin is involved in the regulation of abnormal cell growth and proliferation. In this study, to better understand the merlin's mechanisms that contribute to the inhibition of tumorigenesis, we examined the potential action of merlin on the cell proliferative signaling pathways in response to growth hormone (GH). Merlin effectively attenuated the GH-induced serum response element (SRE) and Elk-1-mediated transcriptional activation, as well as the endogenous SRE-regulated gene c-fos expression in NIH3T3 cells. In addition, merlin prevented the Raf-1 complex activation process, which resulted in the suppression of MAP kinase/ERK, extracellular signal-regulated kinase (ERKs), and Elk-1 phosphorylation, which are the downstream signals of Raf-1. Moreover, it was shown that merlin interacted with endogenous growth factor receptor bound 2 (Grb2) protein and inhibited its expression. These results suggest that merlin contributes, via its protein-to-protein interaction with Grb2 and consequent inhibition of the MAPK pathways, to the regulation of the abnormal cell proliferation, and this provides a further mechanism underlying the tumor suppressor function of merlin.

  6. The deubiquitinating enzyme activity of USP22 is necessary for regulating HeLa cell growth.

    PubMed

    Liu, Ying-Li; Zheng, Jie; Tang, Li-Juan; Han, Wei; Wang, Jian-Min; Liu, Dian-Wu; Tian, Qing-Bao

    2015-11-01

    Ubiquitin-specific protease 22 (USP22) can regulate the cell cycle and apoptosis in many cancer cell types, while it is still unclear whether the deubiquitinating enzyme activity of USP22 is necessary for these processes. As little is known about the impact of USP22 on the growth of HeLa cell, we observed whether USP22 can effectively regulate HeLa cell growth as well as the necessity of deubiquitinating enzyme activity for these processes in HeLa cell. In this study, we demonstrate that USP22 can regulate cell cycle but not apoptosis in HeLa cell. The deubiquitinating enzyme activity of USP22 is necessary for this process as confirmed by an activity-deleted mutant (C185S) and an activity-decreased mutant (Y513C). In addition, the deubiquitinating enzyme activity of USP22 is related to the levels of BMI-1, c-Myc, cyclin D2 and p53. Our findings indicate that the deubiquitinating enzyme activity of USP22 is necessary for regulating HeLa cell growth, and it promotes cell proliferation via the c-Myc/cyclin D2, BMI-1 and p53 pathways in HeLa cell.

  7. Complex quorum-sensing regulatory systems regulate bacterial growth and symbiotic nodulation in Mesorhizobium tianshanense.

    PubMed

    Cao, Huijuan; Yang, Menghua; Zheng, Huiming; Zhang, Jiang; Zhong, Zengtao; Zhu, Jun

    2009-03-01

    LuxR/LuxI-type quorum-sensing systems have been shown to be important for symbiotic interactions between a number of rhizobium species and host legumes. In this study, we found that different isolates of Mesorhizobium tianshanense, a moderately-growing Rhizobium that forms nodules on a number of types of licorice plants, produces several different N-acyl homoserine lactone-like molecules. In M. tianshanense CCBAU060A, we performed a genetic screen and identified a network of regulatory components including a set of LuxI/LuxR-family regulators as well as a MarR-family regulator that is required for quorum-sensing regulation. Furthermore, compared with the wild-type strains, quorum-sensing deficient mutants showed a reduced growth rate and were defective in nodule formation on their host plant Glycyrrhiza uralensis. These data suggest that different M. tianshanense strains may use diverse quorum-sensing systems to regulate symbiotic process.

  8. RNA-binding proteins and translational regulation in axons and growth cones

    PubMed Central

    Hörnberg, Hanna; Holt, Christine

    2013-01-01

    RNA localization and regulation play an important role in the developing and adult nervous system. In navigating axons, extrinsic cues can elicit rapid local protein synthesis that mediates directional or morphological responses. The mRNA repertoire in axons is large and dynamically changing, yet studies suggest that only a subset of these mRNAs are translated after cue stimulation, suggesting the need for a high level of translational regulation. Here, we review the role of RNA-binding proteins (RBPs) as local regulators of translation in developing axons. We focus on their role in growth, guidance, and synapse formation, and discuss the mechanisms by which they regulate translation in axons. PMID:23734093

  9. Cell size and growth regulation in the Arabidopsis thaliana apical stem cell niche

    PubMed Central

    Willis, Lisa; Refahi, Yassin; Wightman, Raymond; Landrein, Benoit; Teles, José; Huang, Kerwyn Casey; Meyerowitz, Elliot M.

    2016-01-01

    Cell size and growth kinetics are fundamental cellular properties with important physiological implications. Classical studies on yeast, and recently on bacteria, have identified rules for cell size regulation in single cells, but in the more complex environment of multicellular tissues, data have been lacking. In this study, to characterize cell size and growth regulation in a multicellular context, we developed a 4D imaging pipeline and applied it to track and quantify epidermal cells over 3–4 d in Arabidopsis thaliana shoot apical meristems. We found that a cell size checkpoint is not the trigger for G2/M or cytokinesis, refuting the unexamined assumption that meristematic cells trigger cell cycle phases upon reaching a critical size. Our data also rule out models in which cells undergo G2/M at a fixed time after birth, or by adding a critical size increment between G2/M transitions. Rather, cell size regulation was intermediate between the critical size and critical increment paradigms, meaning that cell size fluctuations decay by ∼75% in one generation compared with 100% (critical size) and 50% (critical increment). Notably, this behavior was independent of local cell–cell contact topologies and of position within the tissue. Cells grew exponentially throughout the first >80% of the cell cycle, but following an asymmetrical division, the small daughter grew at a faster exponential rate than the large daughter, an observation that potentially challenges present models of growth regulation. These growth and division behaviors place strong constraints on quantitative mechanistic descriptions of the cell cycle and growth control. PMID:27930326

  10. Drosophila Spidey/Kar Regulates Oenocyte Growth via PI3-Kinase Signaling

    PubMed Central

    Cinnamon, Einat; Sawala, Annick; Tittiger, Claus; Paroush, Ze'ev

    2016-01-01

    Cell growth and proliferation depend upon many different aspects of lipid metabolism. One key signaling pathway that is utilized in many different anabolic contexts involves Phosphatidylinositide 3-kinase (PI3K) and its membrane lipid products, the Phosphatidylinositol (3,4,5)-trisphosphates. It remains unclear, however, which other branches of lipid metabolism interact with the PI3K signaling pathway. Here, we focus on specialized fat metabolizing cells in Drosophila called larval oenocytes. In the presence of dietary nutrients, oenocytes undergo PI3K-dependent cell growth and contain very few lipid droplets. In contrast, during starvation, oenocytes decrease PI3K signaling, shut down cell growth and accumulate abundant lipid droplets. We now show that PI3K in larval oenocytes, but not in fat body cells, functions to suppress lipid droplet accumulation. Several enzymes of fatty acid, triglyceride and hydrocarbon metabolism are required in oenocytes primarily for lipid droplet induction rather than for cell growth. In contrast, a very long chain fatty-acyl-CoA reductase (FarO) and a putative lipid dehydrogenase/reductase (Spidey, also known as Kar) not only promote lipid droplet induction but also inhibit oenocyte growth. In the case of Spidey/Kar, we show that the growth suppression mechanism involves inhibition of the PI3K signaling pathway upstream of Akt activity. Together, the findings in this study show how Spidey/Kar and FarO regulate the balance between the cell growth and lipid storage of larval oenocytes. PMID:27500738

  11. Fatty acid regulates gene expression and growth of human prostate cancer PC-3 cells

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.; Chen, Y.; Tjandrawinata, R. R.

    2001-01-01

    It has been proposed that the omega-6 fatty acids increase the rate of tumor growth. Here we test that hypothesis in the PC-3 human prostate tumor. We found that the essential fatty acids, linoleic acid (LA) and arachidonic acid (AA), and the AA metabolite PGE(2) stimulate tumor growth while oleic acid (OA) and the omega-3 fatty acid, eicosapentaenoic acid (EPA) inhibited growth. In examining the role of AA in growth response, we extended our studies to analyze changes in early gene expression induced by AA. We demonstrate that c-fos expression is increased within minutes of addition in a dose-dependent manner. Moreover, the immediate early gene cox-2 is also increased in the presence of AA in a dose-dependent manner, while the constitutive cox-1 message was not increased. Three hours after exposure to AA, the synthesis of PGE(2) via COX-2 was also increased. Previous studies have demonstrated that AA was primarily delivered by low density lipoprotein (LDL) via its receptor (LDLr). Since it is known that hepatomas, acute myelogenous leukemia and colorectal tumors lack normal cholesterol feedback, we examined the role of the LDLr in growth regulation of the PC-3 prostate cancer cells. Analysis of ldlr mRNA expression and LDLr function demonstrated that human PC-3 prostate cancer cells lack normal feedback regulation. While exogenous LDL caused a significant stimulation of cell growth and PGE(2) synthesis, no change was seen in regulation of the LDLr by LDL. Taken together, these data show that normal cholesterol feedback of ldlr message and protein is lost in prostate cancer. These data suggest that unregulated over-expression of LDLr in tumor cells would permit increased availability of AA, which induces immediate early genes c-fos and cox-2 within minutes of uptake.

  12. Target of rapamycin signaling regulates metabolism, growth, and life span in Arabidopsis.

    PubMed

    Ren, Maozhi; Venglat, Prakash; Qiu, Shuqing; Feng, Li; Cao, Yongguo; Wang, Edwin; Xiang, Daoquan; Wang, Jinghe; Alexander, Danny; Chalivendra, Subbaiah; Logan, David; Mattoo, Autar; Selvaraj, Gopalan; Datla, Raju

    2012-12-01

    Target of Rapamycin (TOR) is a major nutrition and energy sensor that regulates growth and life span in yeast and animals. In plants, growth and life span are intertwined not only with nutrient acquisition from the soil and nutrition generation via photosynthesis but also with their unique modes of development and differentiation. How TOR functions in these processes has not yet been determined. To gain further insights, rapamycin-sensitive transgenic Arabidopsis thaliana lines (BP12) expressing yeast FK506 Binding Protein12 were developed. Inhibition of TOR in BP12 plants by rapamycin resulted in slower overall root, leaf, and shoot growth and development leading to poor nutrient uptake and light energy utilization. Experimental limitation of nutrient availability and light energy supply in wild-type Arabidopsis produced phenotypes observed with TOR knockdown plants, indicating a link between TOR signaling and nutrition/light energy status. Genetic and physiological studies together with RNA sequencing and metabolite analysis of TOR-suppressed lines revealed that TOR regulates development and life span in Arabidopsis by restructuring cell growth, carbon and nitrogen metabolism, gene expression, and rRNA and protein synthesis. Gain- and loss-of-function Ribosomal Protein S6 (RPS6) mutants additionally show that TOR function involves RPS6-mediated nutrition and light-dependent growth and life span in Arabidopsis.

  13. Glucolipotoxicity diminishes cardiomyocyte TFEB and inhibits lysosomal autophagy during obesity and diabetes.

    PubMed

    Trivedi, Purvi C; Bartlett, Jordan J; Perez, Lester J; Brunt, Keith R; Legare, Jean Francois; Hassan, Ansar; Kienesberger, Petra C; Pulinilkunnil, Thomas

    2016-12-01

    Impaired cardiac metabolism in the obese an