Arrested development of the myxozoan parasite, Myxobolus cerebralis, in certain populations of mitochondrial 16S lineage III Tubifex tubifex.

PubMed

Baxa, D V; Kelley, G O; Mukkatira, K S; Beauchamp, K A; Rasmussen, C; Hedrick, R P

2008-01-01

Laboratory populations of Tubifex tubifex from mitochondrial (mt)16S ribosomal DNA (rDNA) lineage III were generated from single cocoons of adult worms releasing the triactinomyxon stages (TAMs) of the myxozoan parasite, Myxobolus cerebralis. Subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of M. cerebralis. Development and release of TAMs occurred in five clonal lines, while four clonal lines showed immature parasitic forms that were not expelled from the worm (non-TAM producers). Oligochaetes from TAM- and non-TAM-producing clonal lines were confirmed as lineage III based on mt16S rDNA and internal transcribed spacer region 1 (ITS1) sequences, but these genes did not differentiate these phenotypes. In contrast, random amplified polymorphic DNA analyses of genomic DNA demonstrated unique banding patterns that distinguished the phenotypes. Cohabitation of parasite-exposed TAM- and non-TAM-producing phenotypes showed an overall decrease in expected TAM production compared to the same exposure dose of the TAM-producing phenotype without cohabitation. These studies suggest that differences in susceptibility to parasite infection can occur in genetically similar T. tubifex populations, and their coexistence may affect overall M. cerebralis production, a factor that may influence the severity of whirling disease in wild trout populations.

Mitochondrial lineage A2ah found in a pre-Hispanic individual from the Andean region.

PubMed

Russo, M G; Dejean, C B; Avena, S A; Seldes, V; Ramundo, P

2018-05-10

The aim of this study was to contribute to the knowledge of pre-Hispanic Andean mitochondrial diversity by analyzing an individual from the archaeological site Pukara de La Cueva (North-western Argentina). The date of the discovery context (540 ± 60 BP) corresponds to the Regional Developments II period. Two separate DNA extractions were performed from dentin powder of one tooth. HVR I was amplified by PCR from each extract in three overlapping fragments and the haplotype was determined by consensus among all obtained sequences. The procedures were carried out under strict protocols developed for working with ancient DNA. The individual belonged to the A2ah lineage due to the presence of the 16097C and 16098G transitions, which constitute its distinctive motif. This lineage is very rare in Native American populations and was described in four individuals from current groups inhabiting the Bolivian Llanos, two from South-eastern Brazil, and one from the Gran Chaco region. In addition, two other mutations (16260T and 16286T) were shared with one of the individuals from the Bolivian Llanos region. Considering that the origin of this lineage was postulated for the South American lowlands, the present pre-Hispanic discovery in the Andean area could be taken as a new evidence of gene flow between these regions. Also, it allows the questioning of the geographical origin of this mitochondrial lineage. © 2018 Wiley Periodicals, Inc.

Myopathy caused by mammalian target of rapamycin complex 1 (mTORC1) inactivation is not reversed by restoring mitochondrial function

PubMed Central

Romanino, Klaas; Mazelin, Laetitia; Albert, Verena; Conjard-Duplany, Agnès; Lin, Shuo; Bentzinger, C. Florian; Handschin, Christoph; Puigserver, Pere; Zorzato, Francesco; Schaeffer, Laurent; Gangloff, Yann-Gaël; Rüegg, Markus A.

2011-01-01

Mammalian target of rapamycin complex 1 (mTORC1) is central to the control of cell, organ, and body size. Skeletal muscle-specific inactivation of mTORC1 in mice results in smaller muscle fibers, fewer mitochondria, increased glycogen stores, and a progressive myopathy that causes premature death. In mTORC1-deficient muscles, peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), which regulates mitochondrial biogenesis and glucose homeostasis, is strongly down-regulated. Here we tested whether induction of mitochondrial biogenesis pharmacologically or by the overexpression of PGC-1α is sufficient to reverse the phenotype of mice deficient for mTORC1. We show that both approaches normalize mitochondrial function, such as oxidative capacity and expression of mitochondrial genes. However, they do not prevent or delay the progressive myopathy. In addition, we find that mTORC1 has a much stronger effect than PGC-1α on the glycogen content in muscle. This effect is based on the strong activation of PKB/Akt in mTORC1-deficient mice. We also show that activation of PKB/Akt not only affects glycogen synthesis but also diminishes glycogen degradation. Thus, our work provides strong functional evidence that mitochondrial dysfunction in mice with inactivated mTORC1 signaling is caused by the down-regulation of PGC-1α. However, our data also show that the impairment of mitochondria does not lead directly to the lethal myopathy. PMID:22143799

Phylogenetic utility, and variability in structure and content, of complete mitochondrial genomes among genetic lineages of the Hawaiian anchialine shrimp Halocaridina rubra Holthuis 1963 (Atyidae:Decapoda).

PubMed

Justice, Joshua L; Weese, David A; Santos, Scott Ross

2016-07-01

The Atyidae are caridean shrimp possessing hair-like setae on their claws and are important contributors to ecological services in tropical and temperate fresh and brackish water ecosystems. Complete mitochondrial genomes have only been reported from five of the 449 species in the family, thus limiting understanding of mitochondrial genome evolution and the phylogenetic utility of complete mitochondrial sequences in the Atyidae. Here, comparative analyses of complete mitochondrial genomes from eight genetic lineages of Halocaridina rubra, an atyid endemic to the anchialine ecosystem of the Hawaiian Archipelago, are presented. Although gene number, order, and orientation were syntenic among genomes, three regions were identified and further quantified where conservation was substantially lower: (1) high length and sequence variability in the tRNA-Lys and tRNA-Asp intergenic region; (2) a 317-bp insertion between the NAD6 and CytB genes confined to a single lineage and representing a partial duplication of CytB; and (3) the putative control region. Phylogenetic analyses utilizing complete mitochondrial sequences provided new insights into relationships among the H. rubra genetic lineages, with the topology of one clade correlating to the geologic sequence of the islands. However, deeper nodes in the phylogeny lacked bootstrap support. Overall, our results from H. rubra suggest intra-specific mitochondrial genomic diversity could be underestimated across the Metazoa since the vast majority of complete genomes are from just a single individual of a species.

Fine Dissection of Human Mitochondrial DNA Haplogroup HV Lineages Reveals Paleolithic Signatures from European Glacial Refugia

PubMed Central

Sarno, Stefania; Sevini, Federica; Vianello, Dario; Tamm, Erika; Metspalu, Ene; van Oven, Mannis; Hübner, Alexander; Sazzini, Marco; Franceschi, Claudio; Pettener, Davide; Luiselli, Donata

2015-01-01

Genetic signatures from the Paleolithic inhabitants of Eurasia can be traced from the early divergent mitochondrial DNA lineages still present in contemporary human populations. Previous studies already suggested a pre-Neolithic diffusion of mitochondrial haplogroup HV*(xH,V) lineages, a relatively rare class of mtDNA types that includes parallel branches mainly distributed across Europe and West Asia with a certain degree of structure. Up till now, variation within haplogroup HV was addressed mainly by analyzing sequence data from the mtDNA control region, except for specific sub-branches, such as HV4 or the widely distributed haplogroups H and V. In this study, we present a revised HV topology based on full mtDNA genome data, and we include a comprehensive dataset consisting of 316 complete mtDNA sequences including 60 new samples from the Italian peninsula, a previously underrepresented geographic area. We highlight points of instability in the particular topology of this haplogroup, reconstructed with BEAST-generated trees and networks. We also confirm a major lineage expansion that probably followed the Late Glacial Maximum and preceded Neolithic population movements. We finally observe that Italy harbors a reservoir of mtDNA diversity, with deep-rooting HV lineages often related to sequences present in the Caucasus and the Middle East. The resulting hypothesis of a glacial refugium in Southern Italy has implications for the understanding of late Paleolithic population movements and is discussed within the archaeological cultural shifts occurred over the entire continent. PMID:26640946

mtDNA variation in the Yanomami: evidence for additional New World founding lineages.

PubMed

Easton, R D; Merriwether, D A; Crews, D E; Ferrell, R E

1996-07-01

Native Americans have been classified into four founding haplogroups with as many as seven founding lineages based on mtDNA RFLPs and DNA sequence data. mtDNA analysis was completed for 83 Yanomami from eight villages in the Surucucu and Catrimani Plateau regions of Roraima in northwestern Brazil. Samples were typed for 15 polymorphic mtDNA sites (14 RFLP sites and 1 deletion site), and a subset was sequenced for both hypervariable regions of the mitochondrial D-loop. Substantial mitochondrial diversity was detected among the Yanomami, five of seven accepted founding haplotypes and three others were observed. Of the 83 samples, 4 (4.8%) were lineage B1, 1 (1.2%) was lineage B2, 31 (37.4%) were lineage C1, 29 (34.9%) were lineage C2, 2 (2.4%) were lineage D1, 6 (7.2%) were lineage D2, 7 (8.4%) were a haplotype we designated "X6," and 3 (3.6%) were a haplotype we designated "X7." Sequence analysis found 43 haplotypes in 50 samples. B2, X6, and X7 are previously unrecognized mitochondrial founding lineage types of Native Americans. The widespread distribution of these haplotypes in the New World and Asia provides support for declaring these lineages to be New World founding types.

mtDNA variation in the Yanomami: evidence for additional New World founding lineages.

PubMed Central

Easton, R. D.; Merriwether, D. A.; Crews, D. E.; Ferrell, R. E.

1996-01-01

Native Americans have been classified into four founding haplogroups with as many as seven founding lineages based on mtDNA RFLPs and DNA sequence data. mtDNA analysis was completed for 83 Yanomami from eight villages in the Surucucu and Catrimani Plateau regions of Roraima in northwestern Brazil. Samples were typed for 15 polymorphic mtDNA sites (14 RFLP sites and 1 deletion site), and a subset was sequenced for both hypervariable regions of the mitochondrial D-loop. Substantial mitochondrial diversity was detected among the Yanomami, five of seven accepted founding haplotypes and three others were observed. Of the 83 samples, 4 (4.8%) were lineage B1, 1 (1.2%) was lineage B2, 31 (37.4%) were lineage C1, 29 (34.9%) were lineage C2, 2 (2.4%) were lineage D1, 6 (7.2%) were lineage D2, 7 (8.4%) were a haplotype we designated "X6," and 3 (3.6%) were a haplotype we designated "X7." Sequence analysis found 43 haplotypes in 50 samples. B2, X6, and X7 are previously unrecognized mitochondrial founding lineage types of Native Americans. The widespread distribution of these haplotypes in the New World and Asia provides support for declaring these lineages to be New World founding types. PMID:8659527

Arrested development of the myxozoan parasite, Myxobolus cerebralis, in certain populations of mitochondrial 16S lineage III Tubifex tubifex

USGS Publications Warehouse

Baxa, D.V.; Kelley, G.O.; Mukkatira, K.S.; Beauchamp, K.A.; Rasmussen, C.; Hedrick, R.P.

2008-01-01

Laboratory populations of Tubifex tubifex from mitochondrial (mt)16S ribosomal DNA (rDNA) lineage III were generated from single cocoons of adult worms releasing the triactinomyxon stages (TAMs) of the myxozoan parasite, Myxobolus cerebralis. Subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of M. cerebralis. Development and release of TAMs occurred in five clonal lines, while four clonal lines showed immature parasitic forms that were not expelled from the worm (non-TAM producers). Oligochaetes from TAM- and non-TAM-producing clonal lines were confirmed as lineage III based on mt16S rDNA and internal transcribed spacer region 1 (ITS1) sequences, but these genes did not differentiate these phenotypes. In contrast, random amplified polymorphic DNA analyses of genomic DNA demonstrated unique banding patterns that distinguished the phenotypes. Cohabitation of parasite-exposed TAM- and non-TAM-producing phenotypes showed an overall decrease in expected TAM production compared to the same exposure dose of the TAM-producing phenotype without cohabitation. These studies suggest that differences in susceptibility to parasite infection can occur in genetically similar T. tubifex populations, and their coexistence may affect overall M. cerebralis production, a factor that may influence the severity of whirling disease in wild trout populations. ?? 2007 Springer-Verlag.

Mitochondrial Genomes of Two Barklice, Psococerastis albimaculata and Longivalvus hyalospilus (Psocoptera: Psocomorpha): Contrasting Rates in Mitochondrial Gene Rearrangement between Major Lineages of Psocodea

PubMed Central

Song, Fan; Zhou, Xuguo; Yang, Qianqian; Li, Zhihong; Cai, Wanzhi

2013-01-01

The superorder Psocodea has ∼10,000 described species in two orders: Psocoptera (barklice and booklice) and Phthiraptera (parasitic lice). One booklouse, Liposcelis bostrychophila and six species of parasitic lice have been sequenced for complete mitochondrial (mt) genomes; these seven species have the most rearranged mt genomes seen in insects. The mt genome of a barklouse, lepidopsocid sp., has also been sequenced and is much less rearranged than those of the booklouse and the parasitic lice. To further understand mt gene rearrangements in the Psocodea, we sequenced the mt genomes of two barklice, Psococerastis albimaculata and Longivalvus hyalospilus, the first representatives from the suborder Psocomorpha, which is the most species-rich suborder of the Psocodea. We found that these two barklice have the least rearranged mt genomes seen in the Psocodea to date: a protein-coding gene (nad3) and five tRNAs (trnN, trnS1, trnE, trnM and trnC) have translocated. Rearrangements of mt genes in these two barklice can be accounted for by two events of tandem duplication followed by random deletions. Phylogenetic analyses of the mt genome sequences support the view that Psocoptera is paraphyletic whereas Phthiraptera is monophyletic. The booklouse, L. bostrychophila (suborder Troctomorpha) is most closely related to the parasitic lice. The barklice (suborders Trogiomorpha and Psocomorpha) are closely related and form a monophyletic group. We conclude that mt gene rearrangement has been substantially faster in the lineage leading to the booklice and the parasitic lice than in the lineage leading to the barklice. Lifestyle change appears to be associated with the contrasting rates in mt gene rearrangements between the two lineages of the Psocodea. PMID:23630609

Hiding deep in the trees: discovery of divergent mitochondrial lineages in Malagasy chameleons of the Calumma nasutum group

PubMed Central

Gehring, Philip-Sebastian; Tolley, Krystal A; Eckhardt, Falk Sebastian; Townsend, Ted M; Ziegler, Thomas; Ratsoavina, Fanomezana; Glaw, Frank; Vences, Miguel

2012-01-01

We conducted a comprehensive molecular phylogenetic study for a group of chameleons from Madagascar (Chamaeleonidae: Calumma nasutum group, comprising seven nominal species) to examine the genetic and species diversity in this widespread genus. Based on DNA sequences of the mitochondrial gene (ND2) from 215 specimens, we reconstructed the phylogeny using a Bayesian approach. Our results show deep divergences among several unnamed mitochondrial lineages that are difficult to identify morphologically. We evaluated lineage diversification using a number of statistical phylogenetic methods (general mixed Yule-coalescent model; SpeciesIdentifier; net p-distances) to objectively delimit lineages that we here consider as operational taxonomic units (OTUs), and for which the taxonomic status remains largely unknown. In addition, we compared molecular and morphological differentiation in detail for one particularly diverse clade (the C. boettgeri complex) from northern Madagascar. To assess the species boundaries within this group we used an integrative taxonomic approach, combining evidence from two independent molecular markers (ND2 and CMOS), together with genital and other external morphological characters, and conclude that some of the newly discovered OTUs are separate species (confirmed candidate species, CCS), while others should best be considered as deep conspecific lineages (DCLs). Our analysis supports a total of 33 OTUs, of which seven correspond to described species, suggesting that the taxonomy of the C. nasutum group is in need of revision. PMID:22957155

Endothelial AMPK Activation Induces Mitochondrial Biogenesis and Stress Adaptation via eNOS-Dependent mTORC1 Signaling

PubMed Central

Li, Chunying; Reif, Michaella M; Craige, Siobhan; Kant, Shashi; Keaney, John F.

2016-01-01

Metabolic stress sensors like AMP-activated protein kinase (AMPK) are known to confer stress adaptation and promote longevity in lower organisms. This study demonstrates that activating the metabolic stress sensor AMP-activated protein kinase (AMPK) in endothelial cells helps maintain normal cellular function by promoting mitochondrial biogenesis and stress adaptation. To better define the mechanisms whereby AMPK promotes endothelial stress resistance, we used 5-aminoimidazole-4-carboxamide riboside (AICAR) to chronically activate AMPK and observed stimulation of mitochondrial biogenesis in wild type mouse endothelium, but not in endothelium from endothelial nitric oxide synthase knockout (eNOS-null) mice. Interestingly, AICAR-enhanced mitochondrial biogenesis was blocked by pretreatment with the mammalian target of rapamycin complex 1 (mTORC1) inhibitor, rapamycin. Further, AICAR stimulated mTORC1 as determined by phosphorylation of its known downstream effectors in wild type, but not eNOS-null, endothelial cells. Together these data indicate that eNOS is needed to couple AMPK activation to mTORC1 and thus promote mitochondrial biogenesis and stress adaptation in the endothelium. These data suggest a novel mechanism for mTORC1 activation that is significant for investigations in vascular dysfunction. PMID:26989010

Mitochondrial O-GlcNAc Transferase (mOGT) Regulates Mitochondrial Structure, Function, and Survival in HeLa Cells*

PubMed Central

Sacoman, Juliana L.; Dagda, Raul Y.; Burnham-Marusich, Amanda R.; Dagda, Ruben K.; Berninsone, Patricia M.

2017-01-01

O-Linked N-acetylglucosamine transferase (OGT) catalyzes O-GlcNAcylation of target proteins and regulates numerous biological processes. OGT is encoded by a single gene that yields nucleocytosolic and mitochondrial isoforms. To date, the role of the mitochondrial isoform of OGT (mOGT) remains largely unknown. Using high throughput proteomics, we identified 84 candidate mitochondrial glycoproteins, of which 44 are novel. Notably, two of the candidate glycoproteins identified (cytochrome oxidase 2 (COX2) and NADH:ubiquinone oxidoreductase core subunit 4 (MT-ND4)) are encoded by mitochondrial DNA. Using siRNA in HeLa cells, we found that reducing endogenous mOGT expression leads to alterations in mitochondrial structure and function, including Drp1-dependent mitochondrial fragmentation, reduction in mitochondrial membrane potential, and a significant loss of mitochondrial content in the absence of mitochondrial ROS. These defects are associated with a compensatory increase in oxidative phosphorylation per mitochondrion. mOGT is also critical for cell survival; siRNA-mediated knockdown of endogenous mOGT protected cells against toxicity mediated by rotenone, a complex I inhibitor. Conversely, reduced expression of both nucleocytoplasmic (ncOGT) and mitochondrial (mOGT) OGT isoforms is associated with increased mitochondrial respiration and elevated glycolysis, suggesting that ncOGT is a negative regulator of cellular bioenergetics. Last, we determined that mOGT is probably involved in the glycosylation of a restricted set of mitochondrial targets. We identified four proteins implicated in mitochondrial biogenesis and metabolism regulation as candidate substrates of mOGT, including leucine-rich PPR-containing protein and mitochondrial aconitate hydratase. Our findings suggest that mOGT is catalytically active in vivo and supports mitochondrial structure, health, and survival, whereas ncOGT predominantly regulates cellular bioenergetics. PMID:28100784

The mitochondrial ND1 m.3337G>A mutation associated to multiple mitochondrial DNA deletions in a patient with Wolfram syndrome and cardiomyopathy

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

Mezghani, Najla; Mnif, Mouna; Mkaouar-Rebai, Emna, E-mail: emna_mkaouar@mail2world.com

Highlights: {yields} We reported a patient with Wolfram syndrome and dilated cardiomyopathy. {yields} We detected the ND1 mitochondrial m.3337G>A mutation in 3 tested tissues (blood leukocytes, buccal mucosa and skeletal muscle). {yields} Long-range PCR amplification revealed the presence of multiple mitochondrial deletions in the skeletal muscle. {yields} The deletions remove several tRNA and protein-coding genes. -- Abstract: Wolfram syndrome (WFS) is a rare hereditary disorder also known as DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness). It is a heterogeneous disease and full characterization of all clinical and biological features of this disorder is difficult. The wide spectrum ofmore » clinical expression, affecting several organs and tissues, and the similarity in phenotype between patients with Wolfram syndrome and those with certain types of respiratory chain diseases suggests mitochondrial DNA (mtDNA) involvement in Wolfram syndrome patients. We report a Tunisian patient with clinical features of moderate Wolfram syndrome including diabetes, dilated cardiomyopathy and neurological complications. The results showed the presence of the mitochondrial ND1 m.3337G>A mutation in almost homoplasmic form in 3 tested tissues of the proband (blood leukocytes, buccal mucosa and skeletal muscle). In addition, the long-range PCR amplifications revealed the presence of multiple deletions of the mitochondrial DNA extracted from the patient's skeletal muscle removing several tRNA and protein-coding genes. Our study reported a Tunisian patient with clinical features of moderate Wolfram syndrome associated with cardiomyopathy, in whom we detected the ND1 m.3337G>A mutation with mitochondrial multiple deletions.« less

Multiple Ethnic Origins of Mitochondrial DNA Lineages for the Population of Mauritius

PubMed Central

Betancor, Eva; Suárez, Nicolás M.; Calaon, Diego; Čaval, Saša; Janoo, Anwar; Pestano, Jose

2014-01-01

This article reports on the first genetic assessment of the contemporary Mauritian population. Small island nodes such as Mauritius played a critical role in historic globalization processes and revealing high-resolution details of labour sourcing is crucial in order to better understand early-modern diaspora events. Mauritius is a particularly interesting case given detailed historic accounts attesting to European (Dutch, French and British), African and Asian points of origin. Ninety-seven samples were analysed for mitochondrial DNA to begin unravelling the complex dynamics of the island's modern population. In corroboration with general demographic information, the majority of maternal lineages were derived from South Asia (58.76%), with Malagasy (16.60%), East/Southeast Asian (11.34%) and Sub-Saharan African (10.21%) also making significant contributions. This study pinpoints specific regional origins for the South Asian genetic contribution, showing a greater influence on the contemporary population from northern and southeast India. Moreover, the analysis of lineages related to the slave trade demonstrated that Madagascar and East Asia were the main centres of origin, with less influence from West Africa. PMID:24676463

Insulin stimulates mitochondrial fusion and function in cardiomyocytes via the Akt-mTOR-NFκB-Opa-1 signaling pathway.

PubMed

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.

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

Phylogenetic analysis of Sicilian goats reveals a new mtDNA lineage.

PubMed

Sardina, M T; Ballester, M; Marmi, J; Finocchiaro, R; van Kaam, J B C H M; Portolano, B; Folch, J M

2006-08-01

The mitochondrial hypervariable region 1 (HVR1) sequence of 67 goats belonging to the Girgentana, Maltese and Derivata di Siria breeds was partially sequenced in order to present the first phylogenetic characterization of Sicilian goat breeds. These sequences were compared with published sequences of Indian and Pakistani domestic goats and wild goats. Mitochondrial lineage A was observed in most of the Sicilian goats. However, three Girgentana haplotypes were highly divergent from the Capra hircus clade, indicating that a new mtDNA lineage in domestic goats was found.

mSEL-1L deficiency affects vasculogenesis and neural stem cell lineage commitment.

PubMed

Cardano, Marina; Diaferia, Giuseppe R; Conti, Luciano; Baronchelli, Simona; Sessa, Alessandro; Broccoli, Vania; Barbieri, Andrea; De Blasio, Pasquale; Biunno, Ida

2018-04-01

mSEL-1L is a highly conserved ER-resident type I protein, involved in the degradation of misfolded peptides through the ubiquitin-proteasome system (UPS), a pathway known to control the plasticity of the vascular smooth muscle cells (VSMC) phenotype and survival. In this article, we demonstrate that mSEL-1L deficiency interferes with the murine embryonic vascular network, showing particular irregularities in the intracranic and intersomitic neurovascular units and in the cerebral capillary microcirculation. During murine embryogenesis, mSEL-1L is expressed in cerebral areas known to harbor progenitor neural cells, while in the adult brain the protein is specifically restricted to the stem cell niches, co-localizing with Sox2 and Nestin. Null mice are characterized by important defects in the development of telenchephalic regions, revealing conspicuous aberration in neural stem cell lineage commitment. Moreover, mSEL-1L depletion in vitro and in vivo appears to affect the harmonic differentiation of the NSCs, by negatively influencing the corticogenesis processes. Overall, the data presented suggests that the drastic phenotypic characteristics exhibited in mSEL-1L null mice can, in part, be explained by the negative influence it plays on Notch1 signaling pathway. © 2017 Wiley Periodicals, Inc.

Mitochondrial AKAP1 supports mTOR pathway and tumor growth.

PubMed

Rinaldi, Laura; Sepe, Maria; Delle Donne, Rossella; Conte, Kristel; Arcella, Antonietta; Borzacchiello, Domenica; Amente, Stefano; De Vita, Fernanda; Porpora, Monia; Garbi, Corrado; Oliva, Maria A; Procaccini, Claudio; Faicchia, Deriggio; Matarese, Giuseppe; Zito Marino, Federica; Rocco, Gaetano; Pignatiello, Sara; Franco, Renato; Insabato, Luigi; Majello, Barbara; Feliciello, Antonio

2017-06-01

Mitochondria are the powerhouses of energy production and the sites where metabolic pathway and survival signals integrate and focus, promoting adaptive responses to hormone stimulation and nutrient availability. Increasing evidence suggests that mitochondrial bioenergetics, metabolism and signaling are linked to tumorigenesis. AKAP1 scaffolding protein integrates cAMP and src signaling on mitochondria, regulating organelle biogenesis, oxidative metabolism and cell survival. Here, we provide evidence that AKAP1 is a transcriptional target of Myc and supports the growth of cancer cells. We identify Sestrin2, a leucine sensor and inhibitor of the mammalian target of rapamycin (mTOR), as a novel component of the complex assembled by AKAP1 on mitochondria. Downregulation of AKAP1 impaired mTOR pathway and inhibited glioblastoma growth. Both effects were reversed by concomitant depletion of AKAP1 and sestrin2. High levels of AKAP1 were found in a wide variety of high-grade cancer tissues. In lung cancer, AKAP1 expression correlates with high levels of Myc, mTOR phosphorylation and reduced patient survival. Collectively, these data disclose a previously unrecognized role of AKAP1 in mTOR pathway regulation and cancer growth. AKAP1/mTOR signal integration on mitochondria may provide a new target for cancer therapy.

Historic Late Blight Outbreaks Caused by a Widespread Dominant Lineage of Phytophthora infestans (Mont.) de Bary

PubMed Central

Martin, Michael D.

2016-01-01

Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, was responsible for the Irish potato famine of the 1840s. Initial disease outbreaks occurred in the US in 1843, two years prior to European outbreaks. We examined the evolutionary relationships and source of the 19th-century outbreaks using herbarium specimens of P. infestans from historic (1846–1970) and more recent isolates (1992–2014) of the pathogen. The same unique SSR multilocus genotype, named here as FAM-1, caused widespread outbreaks in both US and Europe. The FAM-1 lineage shared allelic diversity and grouped with the oldest specimens collected in Colombia and Central America. The FAM-1 lineage of P. infestans formed a genetic group that was distinct from more recent aggressive lineages found in the US. The US-1 lineage formed a second, mid-20th century group. Recent modern US lineages and the oldest Mexican lineages formed a genetic group with recent Mexican lineages, suggesting a Mexican origin of recent US lineages. A survey of mitochondrial haplotypes in a larger set of global herbarium specimens documented the more frequent occurrence of the HERB-1 (type Ia) mitochondrial haplotype in archival collections from 1866–75 and 1906–1915 and the rise of the Ib mitochondrial lineage (US-1) between 1946–1955. The FAM-1 SSR lineage survived for almost 100 years in the US, was geographically widespread, and was displaced first in the mid-20th century by the US-1 lineage and then by distinct new aggressive lineages that migrated from Mexico. PMID:28030580

m-AAA and i-AAA complexes coordinate to regulate OMA1, the stress-activated supervisor of mitochondrial dynamics.

PubMed

Consolato, Francesco; Maltecca, Francesca; Tulli, Susanna; Sambri, Irene; Casari, Giorgio

2018-04-09

The proteolytic processing of dynamin-like GTPase OPA1, mediated by the activity of both YME1L1 [intermembrane (i)-AAA protease complex] and OMA1, is a crucial step in the regulation of mitochondrial dynamics. OMA1 is a zinc metallopeptidase of the inner mitochondrial membrane that undergoes pre-activating proteolytic and auto-proteolytic cleavage after mitochondrial import. Here, we identify AFG3L2 [matrix (m) - AAA complex] as the major protease mediating this event, which acts by maturing the 60 kDa pre-pro-OMA1 to the 40 kDa pro-OMA1 form by severing the N-terminal portion without recognizing a specific consensus sequence. Therefore, m - AAA and i - AAA complexes coordinately regulate OMA1 processing and turnover, and consequently control which OPA1 isoforms are present, thus adding new information on the molecular mechanisms of mitochondrial dynamics and neurodegenerative diseases affected by these phenomena.This article has an associated First Person interview with the first author of the paper. © 2018. Published by The Company of Biologists Ltd.

Interbreeding among deeply divergent mitochondrial lineages in the American cockroach (Periplaneta americana)

NASA Astrophysics Data System (ADS)

von Beeren, Christoph; Stoeckle, Mark Y.; Xia, Joyce; Burke, Griffin; Kronauer, Daniel J. C.

2015-02-01

DNA barcoding promises to be a useful tool to identify pest species assuming adequate representation of genetic variants in a reference library. Here we examined mitochondrial DNA barcodes in a global urban pest, the American cockroach (Periplaneta americana). Our sampling effort generated 284 cockroach specimens, most from New York City, plus 15 additional U.S. states and six other countries, enabling the first large-scale survey of P. americana barcode variation. Periplaneta americana barcode sequences (n = 247, including 24 GenBank records) formed a monophyletic lineage separate from other Periplaneta species. We found three distinct P. americana haplogroups with relatively small differences within (<=0.6%) and larger differences among groups (2.4%-4.7%). This could be interpreted as indicative of multiple cryptic species. However, nuclear DNA sequences (n = 77 specimens) revealed extensive gene flow among mitochondrial haplogroups, confirming a single species. This unusual genetic pattern likely reflects multiple introductions from genetically divergent source populations, followed by interbreeding in the invasive range. Our findings highlight the need for comprehensive reference databases in DNA barcoding studies, especially when dealing with invasive populations that might be derived from multiple genetically distinct source populations.

Mitochondrial DNA diversity of honey bees (Apis mellifera) from unmanaged colonies and swarms in the United States.

PubMed

Magnus, Roxane M; Tripodi, Amber D; Szalanski, Allen L

2014-06-01

To study the genetic diversity of honey bees (Apis mellifera L.) from unmanaged colonies in the United States, we sequenced a portion of the mitochondrial DNA COI-COII region. From the 530 to 1,230 bp amplicon, we observed 23 haplotypes from 247 samples collected from 12 states, representing three of the four A. mellifera lineages known to have been imported into the United States (C, M, and O). Six of the 13 C lineage haplotypes were not found in previous queen breeder studies in the United States. The O lineage accounted for 9% of unmanaged colonies which have not yet been reported in queen breeder studies. The M lineage accounted for a larger portion of unmanaged samples (7%) than queen breeder samples (3%). Based on our mitochondrial DNA data, the genetic diversity of unmanaged honey bees in the United States differs significantly from that of queen breeder populations (p < 0.00001). The detection of genetically distinct maternal lineages of unmanaged honey bees suggests that these haplotypes may have existed outside the managed honey bee population for a long period.

Mitochondrial haplogroup H1 is protective for ischemic stroke in Portuguese patients.

PubMed

Rosa, Alexandra; Fonseca, Benedita V; Krug, Tiago; Manso, Helena; Gouveia, Liliana; Albergaria, Isabel; Gaspar, Gisela; Correia, Manuel; Viana-Baptista, Miguel; Simões, Rita Moiron; Pinto, Amélia Nogueira; Taipa, Ricardo; Ferreira, Carla; Fontes, João Ramalho; Silva, Mário Rui; Gabriel, João Paulo; Matos, Ilda; Lopes, Gabriela; Ferro, José M; Vicente, Astrid M; Oliveira, Sofia A

2008-07-01

The genetic contribution to stroke is well established but it has proven difficult to identify the genes and the disease-associated alleles mediating this effect, possibly because only nuclear genes have been intensely investigated so far. Mitochondrial DNA (mtDNA) has been implicated in several disorders having stroke as one of its clinical manifestations. The aim of this case-control study was to assess the contribution of mtDNA polymorphisms and haplogroups to ischemic stroke risk. We genotyped 19 mtDNA single nucleotide polymorphisms (SNPs) defining the major European haplogroups in 534 ischemic stroke patients and 499 controls collected in Portugal, and tested their allelic and haplogroup association with ischemic stroke risk. Haplogroup H1 was found to be significantly less frequent in stroke patients than in controls (OR = 0.61, 95% CI = 0.45-0.83, p = 0.001), when comparing each clade against all other haplogroups pooled together. Conversely, the pre-HV/HV and U mtDNA lineages emerge as potential genetic factors conferring risk for stroke (OR = 3.14, 95% CI = 1.41-7.01, p = 0.003, and OR = 2.87, 95% CI = 1.13-7.28, p = 0.021, respectively). SNPs m.3010G>A, m.7028C>T and m.11719G>A strongly influence ischemic stroke risk, their allelic state in haplogroup H1 corroborating its protective effect. Our data suggests that mitochondrial haplogroup H1 has an impact on ischemic stroke risk in a Portuguese sample.

Diversity of mitochondrial DNA lineages in South Siberia.

PubMed

Derenko, M V; Grzybowski, T; Malyarchuk, B A; Dambueva, I K; Denisova, G A; Czarny, J; Dorzhu, C M; Kakpakov, V T; Miścicka-Sliwka, D; Woźniak, M; Zakharov, I A

2003-09-01

To investigate the origin and evolution of aboriginal populations of South Siberia, a comprehensive mitochondrial DNA (mtDNA) analysis (HVR1 sequencing combined with RFLP typing) of 480 individuals, representing seven Altaic-speaking populations (Altaians, Khakassians, Buryats, Sojots, Tuvinians, Todjins and Tofalars), was performed. Additionally, HVR2 sequence information was obtained for 110 Altaians, providing, in particular, some novel details of the East Asian mtDNA phylogeny. The total sample revealed 81% East Asian (M*, M7, M8, M9, M10, C, D, G, Z, A, B, F, N9a, Y) and 17% West Eurasian (H, U, J, T, I, N1a, X) matrilineal genetic contribution, but with regional differences within South Siberia. The highest influx of West Eurasian mtDNAs was observed in populations from the East Sayan and Altai regions (from 12.5% to 34.5%), whereas in populations from the Baikal region this contribution was markedly lower (less than 10%). The considerable substructure within South Siberian haplogroups B, F, and G, together with the high degree of haplogroup C and D diversity revealed there, allows us to conclude that South Siberians carry the genetic imprint of early-colonization phase of Eurasia. Statistical analyses revealed that South Siberian populations contain high levels of mtDNA diversity and high heterogeneity of mtDNA sequences among populations (Fst = 5.05%) that might be due to geography but not due to language and anthropological features.

Mdivi-1, mitochondrial fission inhibitor, impairs developmental competence and mitochondrial function of embryos and cells in pigs

PubMed Central

YEON, Ji-Yeong; MIN, Sung-Hun; PARK, Hyo-Jin; KIM, Jin-Woo; LEE, Yong-Hee; PARK, Soo-Yong; JEONG, Pil-Soo; PARK, Humdai; LEE, Dong-Seok; KIM, Sun-Uk; CHANG, Kyu-Tae; KOO, Deog-Bon

2014-01-01

Mitochondria are highly dynamic organelles that undergo constant fusion/fission as well as activities orchestrated by large dynamin-related GTPases. These dynamic mitochondrial processes influence mitochondrial morphology, size and function. Therefore, this study was conducted to evaluate the effects of mitochondrial fission inhibitor, mdivi-1, on developmental competence and mitochondrial function of porcine embryos and primary cells. Presumptive porcine embryos were cultured in PZM-3 medium supplemented with mdivi-1 (0, 10 and 50 μM) for 6 days. Porcine fibroblast cells were cultured in growth medium with mdivi-1 (0 and 50 μM) for 2 days. Our results showed that the rate of blastocyst production and cell growth in the mdivi-1 (50 μM) treated group was lower than that of the control group (P < 0.05). Moreover, loss of mitochondrial membrane potential in the mdivi-1 (50 μM) treated group was increased relative to the control group (P < 0.05). Subsequent evaluation revealed that the intracellular levels of reactive oxygen species (ROS) and the apoptotic index were increased by mdivi-1 (50 μM) treatment (P < 0.05). Finally, the expression of mitochondrial fission-related protein (Drp 1) was lower in the embryos and cells in the mdivi-1-treated group than the control group. Taken together, these results indicate that mdivi-1 treatment may inhibit developmental competence and mitochondrial function in porcine embryos and primary cells. PMID:25501014

A Predominantly Neolithic Origin for European Paternal Lineages

PubMed Central

Balaresque, Patricia; Bowden, Georgina R.; Adams, Susan M.; Leung, Ho-Yee; King, Turi E.; Rosser, Zoë H.; Goodwin, Jane; Moisan, Jean-Paul; Richard, Christelle; Millward, Ann; Demaine, Andrew G.; Barbujani, Guido; Previderè, Carlo; Wilson, Ian J.; Tyler-Smith, Chris; Jobling, Mark A.

2010-01-01

The relative contributions to modern European populations of Paleolithic hunter-gatherers and Neolithic farmers from the Near East have been intensely debated. Haplogroup R1b1b2 (R-M269) is the commonest European Y-chromosomal lineage, increasing in frequency from east to west, and carried by 110 million European men. Previous studies suggested a Paleolithic origin, but here we show that the geographical distribution of its microsatellite diversity is best explained by spread from a single source in the Near East via Anatolia during the Neolithic. Taken with evidence on the origins of other haplogroups, this indicates that most European Y chromosomes originate in the Neolithic expansion. This reinterpretation makes Europe a prime example of how technological and cultural change is linked with the expansion of a Y-chromosomal lineage, and the contrast of this pattern with that shown by maternally inherited mitochondrial DNA suggests a unique role for males in the transition. PMID:20087410

Cryptic variation in an ecological indicator organism: mitochondrial and nuclear DNA sequence data confirm distinct lineages of Baetis harrisoni Barnard (Ephemeroptera: Baetidae) in southern Africa

PubMed Central

2012-01-01

Background Baetis harrisoni Barnard is a mayfly frequently encountered in river studies across Africa, but the external morphological features used for identifying nymphs have been observed to vary subtly between different geographic locations. It has been associated with a wide range of ecological conditions, including pH extremes of pH 2.9–10.0 in polluted waters. We present a molecular study of the genetic variation within B. harrisoni across 21 rivers in its distribution range in southern Africa. Results Four gene regions were examined, two mitochondrial (cytochrome c oxidase subunit I [COI] and small subunit ribosomal 16S rDNA [16S]) and two nuclear (elongation factor 1 alpha [EF1α] and phosphoenolpyruvate carboxykinase [PEPCK]). Bayesian and parsimony approaches to phylogeny reconstruction resulted in five well-supported major lineages, which were confirmed using a general mixed Yule-coalescent (GMYC) model. Results from the EF1α gene were significantly incongruent with both mitochondrial and nuclear (PEPCK) results, possibly due to incomplete lineage sorting of the EF1α gene. Mean between-clade distance estimated using the COI and PEPCK data was found to be an order of magnitude greater than the within-clade distance and comparable to that previously reported for other recognised Baetis species. Analysis of the Isolation by Distance (IBD) between all samples showed a small but significant effect of IBD. Within each lineage the contribution of IBD was minimal. Tentative dating analyses using an uncorrelated log-normal relaxed clock and two published estimates of COI mutation rates suggest that diversification within the group occurred throughout the Pliocene and mid-Miocene (~2.4–11.5 mya). Conclusions The distinct lineages of B. harrisoni correspond to categorical environmental variation, with two lineages comprising samples from streams that flow through acidic Table Mountain Sandstone and three lineages with samples from neutral-to-alkaline streams

AmericaPlex26: A SNaPshot Multiplex System for Genotyping the Main Human Mitochondrial Founder Lineages of the Americas

PubMed Central

Coutinho, Alexandra; Valverde, Guido; Fehren-Schmitz, Lars; Cooper, Alan; Barreto Romero, Maria Inés; Espinoza, Isabel Flores; Llamas, Bastien; Haak, Wolfgang

2014-01-01

Phylogeographic studies have described a reduced genetic diversity in Native American populations, indicative of one or more bottleneck events during the peopling and prehistory of the Americas. Classical sequencing approaches targeting the mitochondrial diversity have reported the presence of five major haplogroups, namely A, B, C, D and X, whereas the advent of complete mitochondrial genome sequencing has recently refined the number of founder lineages within the given diversity to 15 sub-haplogroups. We developed and optimized a SNaPshot assay to study the mitochondrial diversity in pre-Columbian Native American populations by simultaneous typing of 26 single nucleotide polymorphisms (SNPs) characterising Native American sub-haplogroups. Our assay proved to be highly sensitive with respect to starting concentrations of target DNA and could be applied successfully to a range of ancient human skeletal material from South America from various time periods. The AmericaPlex26 is a powerful assay with enhanced phylogenetic resolution that allows time- and cost-efficient mitochondrial DNA sub-typing from valuable ancient specimens. It can be applied in addition or alternative to standard sequencing of the D-loop region in forensics, ancestry testing, and population studies, or where full-resolution mitochondrial genome sequencing is not feasible. PMID:24671218

AmericaPlex26: a SNaPshot multiplex system for genotyping the main human mitochondrial founder lineages of the Americas.

PubMed

Coutinho, Alexandra; Valverde, Guido; Fehren-Schmitz, Lars; Cooper, Alan; Barreto Romero, Maria Inés; Espinoza, Isabel Flores; Llamas, Bastien; Haak, Wolfgang

2014-01-01

Phylogeographic studies have described a reduced genetic diversity in Native American populations, indicative of one or more bottleneck events during the peopling and prehistory of the Americas. Classical sequencing approaches targeting the mitochondrial diversity have reported the presence of five major haplogroups, namely A, B, C, D and X, whereas the advent of complete mitochondrial genome sequencing has recently refined the number of founder lineages within the given diversity to 15 sub-haplogroups. We developed and optimized a SNaPshot assay to study the mitochondrial diversity in pre-Columbian Native American populations by simultaneous typing of 26 single nucleotide polymorphisms (SNPs) characterising Native American sub-haplogroups. Our assay proved to be highly sensitive with respect to starting concentrations of target DNA and could be applied successfully to a range of ancient human skeletal material from South America from various time periods. The AmericaPlex26 is a powerful assay with enhanced phylogenetic resolution that allows time- and cost-efficient mitochondrial DNA sub-typing from valuable ancient specimens. It can be applied in addition or alternative to standard sequencing of the D-loop region in forensics, ancestry testing, and population studies, or where full-resolution mitochondrial genome sequencing is not feasible.

Mitochondrial haplogroup N1a phylogeography, with implication to the origin of European farmers.

PubMed

Palanichamy, Malliya Gounder; Zhang, Cai-Ling; Mitra, Bikash; Malyarchuk, Boris; Derenko, Miroslava; Chaudhuri, Tapas Kumar; Zhang, Ya-Ping

2010-10-12

Tracing the genetic origin of central European farmer N1a lineages can provide a unique opportunity to assess the patterns of the farming technology spread into central Europe in the human prehistory. Here, we have chosen twelve N1a samples from modern populations which are most similar with the farmer N1a types and performed the complete mitochondrial DNA genome sequencing analysis. To assess the genetic and phylogeographic relationship, we performed a detailed survey of modern published N1a types from Eurasian and African populations. The geographic origin and expansion of farmer lineages related N1a subclades have been deduced from combined analysis of 19 complete sequences with 166 N1a haplotypes. The phylogeographic analysis revealed that the central European farmer lineages have originated from different sources: from eastern Europe, local central Europe, and from the Near East via southern Europe. The results obtained emphasize that the arrival of central European farmer lineages did not occur via a single demic diffusion event from the Near East at the onset of the Neolithic spread of agriculture into Europe. Indeed these results indicate that the Neolithic transition process was more complex in central Europe and possibly the farmer N1a lineages were a result of a 'leapfrog' colonization process.

An Essential Role for COPI in mRNA Localization to Mitochondria and Mitochondrial Function.

PubMed

Zabezhinsky, Dmitry; Slobodin, Boris; Rapaport, Doron; Gerst, Jeffrey E

2016-04-19

Nuclear-encoded mRNAs encoding mitochondrial proteins (mMPs) can localize directly to the mitochondrial surface, yet how mMPs target mitochondria and whether RNA targeting contributes to protein import into mitochondria and cellular metabolism are unknown. Here, we show that the COPI vesicle coat complex is necessary for mMP localization to mitochondria and mitochondrial function. COPI inactivation leads to reduced mMP binding to COPI itself, resulting in the dissociation of mMPs from mitochondria, a reduction in mitochondrial membrane potential, a decrease in protein import in vivo and in vitro, and severe deficiencies in mitochondrial respiration. Using a model mMP (OXA1), we observed that COPI inactivation (or mutation of the potential COPI-interaction site) led to altered mRNA localization and impaired cellular respiration. Overall, COPI-mediated mMP targeting is critical for mitochondrial protein import and function, and transcript delivery to the mitochondria or endoplasmic reticulum is regulated by cis-acting RNA sequences and trans-acting proteins. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Defining a Model for Mitochondrial Function in mESC Differentiation

EPA Science Inventory

Defining a Model for Mitochondrial Function in mESC DifferentiationDefining a Model for Mitochondrial Function in mESC Differentiation Differentiating embryonic stem cells (ESCs) undergo mitochondrial maturation leading to a switch from a system dependent upon glycolysis to a re...

Comparative and Evolutionary Analyses of Meloidogyne spp. Based on Mitochondrial Genome Sequences

PubMed Central

García, Laura Evangelina; Sánchez-Puerta, M. Virginia

2015-01-01

Molecular taxonomy and evolution of nematodes have been recently the focus of several studies. Mitochondrial sequences were proposed as an alternative for precise identification of Meloidogyne species, to study intraspecific variability and to follow maternal lineages. We characterized the mitochondrial genomes (mtDNAs) of the root knot nematodes M. floridensis, M. hapla and M. incognita. These were AT rich (81–83%) and highly compact, encoding 12 proteins, 2 rRNAs, and 22 tRNAs. Comparisons with published mtDNAs of M. chitwoodi, M. incognita (another strain) and M. graminicola revealed that they share protein and rRNA gene order but differ in the order of tRNAs. The mtDNAs of M. floridensis and M. incognita were strikingly similar (97–100% identity for all coding regions). In contrast, M. floridensis, M. chitwoodi, M. hapla and M. graminicola showed 65–84% nucleotide identity for coding regions. Variable mitochondrial sequences are potentially useful for evolutionary and taxonomic studies. We developed a molecular taxonomic marker by sequencing a highly-variable ~2 kb mitochondrial region, nad5-cox1, from 36 populations of root-knot nematodes to elucidate relationships within the genus Meloidogyne. Isolates of five species formed monophyletic groups and showed little intraspecific variability. We also present a thorough analysis of the mitochondrial region cox2-rrnS. Phylogenies based on either mitochondrial region had good discrimination power but could not discriminate between M. arenaria, M. incognita and M. floridensis. PMID:25799071

Hypoxic stress induces, but cannot sustain trophoblast stem cell differentiation to labyrinthine placenta due to mitochondrial insufficiency

PubMed Central

Xie, Yufen; Zhou, Sichang; Jiang, Zhongliang; Dai, Jing; Puscheck, Elizabeth E; Lee, Icksoo; Parker, Graham; Hüttemann, Maik; Rappolee, Daniel A

2014-01-01

Dysfunctional stem cell differentiation into placental lineages is associated with gestational diseases. Of the differentiated lineages available to trophoblast stem cells (TSC), elevated O2 and mitochondrial function are necessary to placental lineages at the maternal-placental surface and important in the etiology of preeclampsia. TSC lineage imbalance leads to embryonic failure during uterine implantation. Stress at implantation exacerbates stem cell depletion by decreasing proliferation and increasing differentiation. Implantation site O2 is normally ~2%. In culture, exposure to 2% O2 and fibroblast growth factor (FGF)4 enabled highest mouse TSC multipotency and proliferation. In contrast, hypoxic stress (0.5% O2) initiated the most TSC differentiation after 24 hr despite FGF4. However, hypoxic stress supported differentiation poorly after 4–7 days, despite FGF4 removal. At all tested O2 levels, FGF4 maintained Warburg metabolism; mitochondrial inactivity and aerobic glycolysis. However, hypoxic stress suppressed mitochondrial membrane potential, maintained low mitochondrial cytochrome c oxidase (oxidative phosphorylation/OxPhos), and high pyruvate kinase M2 (glycolysis) despite FGF4 removal. Inhibiting OxPhos inhibited differentiation at the differentiation optimum at 20% O2. Moreover, adding differentiation-inducing hyperosmolar stress failed to induce differentiation during hypoxia. Thus, differentiation depended on OxPhos at 20% O2; hypoxic and hyperosmolar stresses did not induce differentiation at 0.5% O2. Hypoxia-limited differentiation and mitochondrial inhibition and activation suggest that differentiation into two lineages of the labyrinthine placenta requires O2>0.5–2% and mitochondrial function. Stress-activated protein kinase increases an early lineage and suppresses later lineages in proportion to the deviation from optimal O2 for multipotency, thus it is the first enzyme reported to prioritize differentiation. PMID:25239494

Melatonin protects cardiac microvasculature against ischemia/reperfusion injury via suppression of mitochondrial fission-VDAC1-HK2-mPTP-mitophagy axis.

PubMed

Zhou, Hao; Zhang, Ying; Hu, Shunying; Shi, Chen; Zhu, Pingjun; Ma, Qiang; Jin, Qinhua; Cao, Feng; Tian, Feng; Chen, Yundai

2017-08-01

The cardiac microvascular system, which is primarily composed of monolayer endothelial cells, is the site of blood supply and nutrient exchange to cardiomyocytes. However, microvascular ischemia/reperfusion injury (IRI) following percutaneous coronary intervention is a woefully neglected topic, and few strategies are available to reverse such pathologies. Here, we studied the effects of melatonin on microcirculation IRI and elucidated the underlying mechanism. Melatonin markedly reduced infarcted area, improved cardiac function, restored blood flow, and lower microcirculation perfusion defects. Histological analysis showed that cardiac microcirculation endothelial cells (CMEC) in melatonin-treated mice had an unbroken endothelial barrier, increased endothelial nitric oxide synthase expression, unobstructed lumen, reduced inflammatory cell infiltration, and less endothelial damage. In contrast, AMP-activated protein kinase α (AMPKα) deficiency abolished the beneficial effects of melatonin on microvasculature. In vitro, IRI activated dynamin-related protein 1 (Drp1)-dependent mitochondrial fission, which subsequently induced voltage-dependent anion channel 1 (VDAC1) oligomerization, hexokinase 2 (HK2) liberation, mitochondrial permeability transition pore (mPTP) opening, PINK1/Parkin upregulation, and ultimately mitophagy-mediated CMEC death. However, melatonin strengthened CMEC survival via activation of AMPKα, followed by p-Drp1 S616 downregulation and p-Drp1 S37 upregulation, which blunted Drp1-dependent mitochondrial fission. Suppression of mitochondrial fission by melatonin recovered VDAC1-HK2 interaction that prevented mPTP opening and PINK1/Parkin activation, eventually blocking mitophagy-mediated cellular death. In summary, this study confirmed that melatonin protects cardiac microvasculature against IRI. The underlying mechanism may be attributed to the inhibitory effects of melatonin on mitochondrial fission-VDAC1-HK2-mPTP-mitophagy axis via activation

Phylogenetic relationships among the major lineages of the birds-of-paradise (Paradisaeidae) using mitochondrial DNA gene sequences.

PubMed

Nunn, G B; Cracraft, J

1996-06-01

Complete mitochondrial cytochrome b gene sequences were determined from 12 species of the Australo-Papuan birds-of-paradise (Paradisaeidae) representing 9 genera. Phylogenetic analysis of these and 5 previously published sequences reveals a radiation of the main paradisaeinine lineages that took place over a relatively short evolutionary time scale. The core paradisaeinines are resolved as the monophyletic sister-group to the crow-like manucodines. The genus Parotia is basal to other paradisaeinines and is not closely related to the morphologically similar genera Ptiloris and Lophorina. Three major clades within the paradisaeinine ingroup include: (1) Cicinnurus and Diphyllodes, (2) Ptiloris and Lophorina, and (3) the genus Paradisaea. The monotypic genus Seleucidis is apparently closely related to clades (1) and (2). Cytochrome b sequences did not provide evidence for the monophyly of the sicklebill genera Epimachus and Drepanornis. The paradisaeid tree is characterized by short internodal distances. Thus, some clades cannot be strongly resolved by cytochrome b sequences alone.

m-AAA proteases, mitochondrial calcium homeostasis and neurodegeneration

PubMed Central

Patron, Maria; Sprenger, Hans-Georg; Langer, Thomas

2018-01-01

The function of mitochondria depends on ubiquitously expressed and evolutionary conserved m-AAA proteases in the inner membrane. These ATP-dependent peptidases form hexameric complexes built up of homologous subunits. AFG3L2 subunits assemble either into homo-oligomeric isoenzymes or with SPG7 (paraplegin) subunits into hetero-oligomeric proteolytic complexes. Mutations in AFG3L2 are associated with dominant spinocerebellar ataxia (SCA28) characterized by the loss of Purkinje cells, whereas mutations in SPG7 cause a recessive form of hereditary spastic paraplegia (HSP7) with motor neurons of the cortico-spinal tract being predominantly affected. Pleiotropic functions have been assigned to m-AAA proteases, which act as quality control and regulatory enzymes in mitochondria. Loss of m-AAA proteases affects mitochondrial protein synthesis and respiration and leads to mitochondrial fragmentation and deficiencies in the axonal transport of mitochondria. Moreover m-AAA proteases regulate the assembly of the mitochondrial calcium uniporter (MCU) complex. Impaired degradation of the MCU subunit EMRE in AFG3L2-deficient mitochondria results in the formation of deregulated MCU complexes, increased mitochondrial calcium uptake and increased vulnerability of neurons for calcium-induced cell death. A reduction of calcium influx into the cytosol of Purkinje cells rescues ataxia in an AFG3L2-deficient mouse model. In this review, we discuss the relationship between the m-AAA protease and mitochondrial calcium homeostasis and its relevance for neurodegeneration and describe a novel mouse model lacking MCU specifically in Purkinje cells. Our results pledge for a novel view on m-AAA proteases that integrates their pleiotropic functions in mitochondria to explain the pathogenesis of associated neurodegenerative disorders. PMID:29451229

m-AAA proteases, mitochondrial calcium homeostasis and neurodegeneration.

PubMed

Patron, Maria; Sprenger, Hans-Georg; Langer, Thomas

2018-03-01

The function of mitochondria depends on ubiquitously expressed and evolutionary conserved m-AAA proteases in the inner membrane. These ATP-dependent peptidases form hexameric complexes built up of homologous subunits. AFG3L2 subunits assemble either into homo-oligomeric isoenzymes or with SPG7 (paraplegin) subunits into hetero-oligomeric proteolytic complexes. Mutations in AFG3L2 are associated with dominant spinocerebellar ataxia (SCA28) characterized by the loss of Purkinje cells, whereas mutations in SPG7 cause a recessive form of hereditary spastic paraplegia (HSP7) with motor neurons of the cortico-spinal tract being predominantly affected. Pleiotropic functions have been assigned to m-AAA proteases, which act as quality control and regulatory enzymes in mitochondria. Loss of m-AAA proteases affects mitochondrial protein synthesis and respiration and leads to mitochondrial fragmentation and deficiencies in the axonal transport of mitochondria. Moreover m-AAA proteases regulate the assembly of the mitochondrial calcium uniporter (MCU) complex. Impaired degradation of the MCU subunit EMRE in AFG3L2-deficient mitochondria results in the formation of deregulated MCU complexes, increased mitochondrial calcium uptake and increased vulnerability of neurons for calcium-induced cell death. A reduction of calcium influx into the cytosol of Purkinje cells rescues ataxia in an AFG3L2-deficient mouse model. In this review, we discuss the relationship between the m-AAA protease and mitochondrial calcium homeostasis and its relevance for neurodegeneration and describe a novel mouse model lacking MCU specifically in Purkinje cells. Our results pledge for a novel view on m-AAA proteases that integrates their pleiotropic functions in mitochondria to explain the pathogenesis of associated neurodegenerative disorders.

The complex and diversified mitochondrial gene pool of Berber populations.

PubMed

Coudray, C; Olivieri, A; Achilli, A; Pala, M; Melhaoui, M; Cherkaoui, M; El-Chennawi, F; Kossmann, M; Torroni, A; Dugoujon, J M

2009-03-01

The mitochondrial DNA variation of 295 Berber-speakers from Morocco (Asni, Bouhria and Figuig) and the Egyptian oasis of Siwa was evaluated by sequencing a portion of the control region (including HVS-I and part of HVS-II) and surveying haplogroup-specific coding region markers. Our findings show that the Berber mitochondrial pool is characterized by an overall high frequency of Western Eurasian haplogroups, a somehow lower frequency of sub-Saharan L lineages, and a significant (but differential) presence of North African haplogroups U6 and M1, thus occupying an intermediate position between European and sub-Saharan populations in PCA analysis. A clear and significant genetic differentiation between the Berbers from Maghreb and Egyptian Berbers was also observed. The first are related to European populations as shown by haplogroup H1 and V frequencies, whereas the latter share more affinities with East African and Nile Valley populations as indicated by the high frequency of M1 and the presence of L0a1, L3i, L4*, and L4b2 lineages. Moreover, haplogroup U6 was not observed in Siwa. We conclude that the origins and maternal diversity of Berber populations are old and complex, and these communities bear genetic characteristics resulting from various events of gene flow with surrounding and migrating populations.

Nobiletin attenuates neurotoxic mitochondrial calcium overload through K+ influx and ΔΨm across mitochondrial inner membrane.

PubMed

Lee, Ji Hyung; Amarsanaa, Khulan; Wu, Jinji; Jeon, Sang-Chan; Cui, Yanji; Jung, Sung-Cherl; Park, Deok-Bae; Kim, Se-Jae; Han, Sang-Heon; Kim, Hyun-Wook; Rhyu, Im Joo; Eun, Su-Yong

2018-05-01

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (ΔΨ m ). Therefore, pharmacological manipulation of ΔΨ m can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ΔΨ m against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity (100 µM, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate (100 µM)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of Ca 2+ (5 µM). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ΔΨ m were completely abolished in K + -free medium on pure isolated mitochondria. Taken together, results demonstrate that K + influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial K + influx is probably mediated, at least in part, by activation of mitochondrial K + channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

The MTL1 Pentatricopeptide Repeat Protein Is Required for Both Translation and Splicing of the Mitochondrial NADH DEHYDROGENASE SUBUNIT7 mRNA in Arabidopsis.

PubMed

Haïli, Nawel; Planchard, Noelya; Arnal, Nadège; Quadrado, Martine; Vrielynck, Nathalie; Dahan, Jennifer; des Francs-Small, Catherine Colas; Mireau, Hakim

2016-01-01

Mitochondrial translation involves a complex interplay of ancient bacteria-like features and host-derived functionalities. Although the basic components of the mitochondrial translation apparatus have been recognized, very few protein factors aiding in recruiting ribosomes on mitochondria-encoded messenger RNA (mRNAs) have been identified in higher plants. In this study, we describe the identification of the Arabidopsis (Arabidopsis thaliana) MITOCHONDRIAL TRANSLATION FACTOR1 (MTL1) protein, a new member of the Pentatricopeptide Repeat family, and show that it is essential for the translation of the mitochondrial NADH dehydrogenase subunit7 (nad7) mRNA. We demonstrate that mtl1 mutant plants fail to accumulate the Nad7 protein, even though the nad7 mature mRNA is produced and bears the same 5' and 3' extremities as in wild-type plants. We next observed that polysome association of nad7 mature mRNA is specifically disrupted in mtl1 mutants, indicating that the absence of Nad7 results from a lack of translation of nad7 mRNA. These findings illustrate that mitochondrial translation requires the intervention of gene-specific nucleus-encoded PPR trans-factors and that their action does not necessarily involve the 5' processing of their target mRNA, as observed previously. Interestingly, a partial decrease in nad7 intron 2 splicing was also detected in mtl1 mutants, suggesting that MTL1 is also involved in group II intron splicing. However, this second function appears to be less essential for nad7 expression than its role in translation. MTL1 will be instrumental to understand the multifunctionality of PPR proteins and the mechanisms governing mRNA translation and intron splicing in plant mitochondria. © 2016 American Society of Plant Biologists. All Rights Reserved.

RNA silencing of mitochondrial m-Nfs1 reduces Fe-S enzyme activity both in mitochondria and cytosol of mammalian cells.

PubMed

Fosset, Cédric; Chauveau, Marie-Jeanne; Guillon, Blanche; Canal, Frédéric; Drapier, Jean-Claude; Bouton, Cécile

2006-09-01

In prokaryotes and yeast, the general mechanism of biogenesis of iron-sulfur (Fe-S) clusters involves activities of several proteins among which IscS and Nfs1p provide, through cysteine desulfuration, elemental sulfide for Fe-S core formation. Although these proteins have been well characterized, the role of their mammalian homolog in Fe-S cluster biogenesis has never been evaluated. We report here the first functional study that implicates the putative cysteine desulfurase m-Nfs1 in the biogenesis of both mitochondrial and cytosolic mammalian Fe-S proteins. Depletion of m-Nfs1 in cultured fibroblasts through small interfering RNA-based gene silencing significantly inhibited the activities of mitochondrial NADH-ubiquinone oxidoreductase (complex I) and succinate-ubiquinone oxidoreductase (complex II) of the respiratory chain, as well as aconitase of the Krebs cycle, with no alteration in their protein levels. Activity of cytosolic xanthine oxidase, which holds a [2Fe-2S] cluster, was also specifically reduced, and iron-regulatory protein-1 was converted from its [4Fe-4S] aconitase form to its apo- or RNA-binding form. Reduction of Fe-S enzyme activities occurred earlier and more markedly in the cytosol than in mitochondria, suggesting that there is a mechanism that primarily dedicates m-Nfs1 to the biogenesis of mitochondrial Fe-S clusters in order to maintain cell survival. Finally, depletion of m-Nfs1, which conferred on apo-IRP-1 a high affinity for ferritin mRNA, was associated with the down-regulation of the iron storage protein ferritin.

LL-37 attenuates inflammatory impairment via mTOR signaling-dependent mitochondrial protection.

PubMed

Sun, Wenyan; Zheng, Yan; Lu, Zhuoyang; Wang, Hui; Feng, Zhihui; Wang, Juan; Xiao, Shengxiang; Liu, Feng; Liu, Jiankang

2014-09-01

The human cationic antimicrobial protein LL-37 is a multifunctional host defense peptide with a wide range of immunomodulatory activities. Previous work has shown that LL-37 exerts both pro- and anti-inflammatory effects. The role of mitochondria in the skin inflammatory effects of LL-37 has not been well studied. Therefore, our aim was to investigate the immunomodulatory effect of LL-37 in HaCaT cells and to delineate the underlying mechanisms related to mitochondrial function. Immunohistochemistry results from tissue microarrays showed strong cytoplasmic LL-37 staining in inflammatory cells in chronic dermatic inflammation. Using exogenous LL-37 stimulation and LL-37 knockdown and overexpression, LL-37 was demonstrated to dramatically reduce the mRNA levels and protein secretion of inflammatory cytokines including IL-6, IL-8, IL-1α and tumor necrosis factor-α (TNF-α), which are induced by lipopolysaccharides (LPS). The anti-inflammatory effects of LL-37 are dependent upon its ability to increase mitochondrial biogenesis and to maintain mitochondrial homeostasis. Furthermore, we observed that LL-37 enhances the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK1/2) and mammalian target of rapamycin (mTOR). The mTOR inhibitor rapamycin can neutralize the protective effects of LL-37 on mitochondria. In conclusion, these results suggest that high LL-37 expression levels correlate with chronic skin inflammation; mitochondrial dysfunction occurs in HaCaT cells during inflammation; and LL-37 attenuates inflammatory impairment by stimulating mitochondrial biogenesis and protecting mitochondrial function, which are dependent upon mTOR signaling. These findings provide new insights into targeting mitochondria with LL-37 to prevent skin inflammatory reactions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Three brown trout Salmo trutta lineages in Corsica described through allozyme variation.

PubMed

Berrebi, P

2015-01-01

The brown trout Salmo trutta is represented by three lineages in Corsica: (1) an ancestral Corsican lineage, (2) a Mediterranean lineage and (3) a recently stocked domestic Atlantic S. trutta lineage (all are interfertile); the main focus of this study was the ancestral Corsican S. trutta, but the other lineages were also considered. A total of 38 samples captured between 1993 and 1998 were analysed, with nearly 1000 individuals considered overall. The Corsican ancestral lineage (Adriatic lineage according to the mitochondrial DNA control region nomenclature, AD) mostly inhabits streams in the southern half of the island; the Mediterranean lineage (ME) is present more in the north, especially in Golu River, but most populations are an admixture of these lineages and the domestic Atlantic S. trutta (AT). Locations where the Corsican ancestral S. trutta is dominant are now protected against stocking and sometimes fishing is also forbidden. The presence of the Corsican S. trutta is unique in France. © 2014 The Fisheries Society of the British Isles.

Divergence, hybridization, and recombination in the mitochondrial genome of the human pathogenic yeast Cryptococcus gattii.

PubMed

Xu, Jianping; Yan, Zhun; Guo, Hong

2009-06-01

The inheritance of mitochondrial genes and genomes are uniparental in most sexual eukaryotes. This pattern of inheritance makes mitochondrial genomes in natural populations effectively clonal. Here, we examined the mitochondrial population genetics of the emerging human pathogenic fungus Cryptococcus gattii. The DNA sequences for five mitochondrial DNA fragments were obtained from each of 50 isolates belonging to two evolutionary divergent lineages, VGI and VGII. Our analyses revealed a greater sequence diversity within VGI than that within VGII, consistent with observations of the nuclear genes. The combined analyses of all five gene fragments indicated significant divergence between VGI and VGII. However, the five individual genealogies showed different relationships among the isolates, consistent with recent hybridization and mitochondrial gene transfer between the two lineages. Population genetic analyses of the multilocus data identified evidence for predominantly clonal mitochondrial population structures within both lineages. Interestingly, there were clear signatures of recombination among mitochondrial genes within the VGII lineage. Our analyses suggest historical mitochondrial genome divergence within C. gattii, but there is evidence for recent hybridization and recombination in the mitochondrial genome of this important human yeast pathogen.

Phylogeographic analysis of mitochondrial DNA in northern Asian populations.

PubMed

Derenko, Miroslava; Malyarchuk, Boris; Grzybowski, Tomasz; Denisova, Galina; Dambueva, Irina; Perkova, Maria; Dorzhu, Choduraa; Luzina, Faina; Lee, Hong Kyu; Vanecek, Tomas; Villems, Richard; Zakharov, Ilia

2007-11-01

To elucidate the human colonization process of northern Asia and human dispersals to the Americas, a diverse subset of 71 mitochondrial DNA (mtDNA) lineages was chosen for complete genome sequencing from the collection of 1,432 control-region sequences sampled from 18 autochthonous populations of northern, central, eastern, and southwestern Asia. On the basis of complete mtDNA sequencing, we have revised the classification of haplogroups A, D2, G1, M7, and I; identified six new subhaplogroups (I4, N1e, G1c, M7d, M7e, and J1b2a); and fully characterized haplogroups N1a and G1b, which were previously described only by the first hypervariable segment (HVS1) sequencing and coding-region restriction-fragment-length polymorphism analysis. Our findings indicate that the southern Siberian mtDNA pool harbors several lineages associated with the Late Upper Paleolithic and/or early Neolithic dispersals from both eastern Asia and southwestern Asia/southern Caucasus. Moreover, the phylogeography of the D2 lineages suggests that southern Siberia is likely to be a geographical source for the last postglacial maximum spread of this subhaplogroup to northern Siberia and that the expansion of the D2b branch occurred in Beringia ~7,000 years ago. In general, a detailed analysis of mtDNA gene pools of northern Asians provides the additional evidence to rule out the existence of a northern Asian route for the initial human colonization of Asia.

Identification of two invasive Cacopsylla chinensis (Hemiptera: Psyllidae) lineages based on two mitochondrial sequences and restriction fragment length polymorphism of cytochrome oxidase I amplicon.

PubMed

Lee, Hsien-Chung; Yang, Man-Miao; Yeh, Wen-Bin

2008-08-01

The occurrence of pear decline, a disease found in some pear (Pyrus spp.) orchards of Taiwan in recent years, is accompanied by an outbreak of Cacopsylla chinensis (Yang & Li). Two major morphological forms (summer and winter forms) with a variety of intermediate body color and two phylogenetic lineages of this psyllid have been described. The work herein used sequences of mitochondrial cytochrome oxidase I (COI) and 16S rDNA regions to delineate the genetic differentiation of this color-variable insect and to elucidate their relationship. Sequence divergence and phylogenetic analysis have shown that C. chinensis individuals could be divided into two lineages with 3.3 and 2.3% divergence of COI and 16S rDNA, respectively. All specimens from China were found to belong to lineage I. Restriction fragment length polymorphism analysis of COI with restriction enzymes AcuI, AseI, BccI, and FokI on 263 specimens of six populations from Taiwan produced two digestion patterns, which are in agreement with the two lineages described above. Both patterns could be found in each population, with most individuals belonging to lineage I and 5-21% of the individuals belonging to lineage II. Because these two lineages included summer as well as winter morphological forms, the lineage differentiation is apparently not related to morphological characters of this psyllid. Because the invasive records are not in favor of a sympatric differentiation, this psyllid is more likely introduced as different populations from countries in temperate regions.

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells

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

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics inmore » oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. - Highlights: • Demonstrated first time the link between the mPTP to mitochondrial dynamics. • The role of Cyclophilin D in the regulation of Drp1-mediated mitochondrial fission. • CsA as a potential target for governing oxidative stress related neuropathology.« less

The Elusive Nature of Adaptive Mitochondrial DNA Evolution of an Arctic Lineage Prone to Frequent Introgression

PubMed Central

Melo-Ferreira, José; Vilela, Joana; Fonseca, Miguel M.; da Fonseca, Rute R.; Boursot, Pierre; Alves, Paulo C.

2014-01-01

Mitochondria play a fundamental role in cellular metabolism, being responsible for most of the energy production of the cell in the oxidative phosphorylation (OXPHOS) pathway. Mitochondrial DNA (mtDNA) encodes for key components of this process, but its direct role in adaptation remains far from understood. Hares (Lepus spp.) are privileged models to study the impact of natural selection on mitogenomic evolution because 1) species are adapted to contrasting environments, including arctic, with different metabolic pressures, and 2) mtDNA introgression from arctic into temperate species is widespread. Here, we analyzed the sequences of 11 complete mitogenomes (ten newly obtained) of hares of temperate and arctic origins (including two of arctic origin introgressed into temperate species). The analysis of patterns of codon substitutions along the reconstructed phylogeny showed evidence for positive selection in several codons in genes of the OXPHOS complexes, most notably affecting the arctic lineage. However, using theoretical models, no predictable effect of these differences was found on the structure and physicochemical properties of the encoded proteins, suggesting that the focus of selection may lie on complex interactions with nuclear encoded peptides. Also, a cloverleaf structure was detected in the control region only from the arctic mtDNA lineage, which may influence mtDNA replication and transcription. These results suggest that adaptation impacted the evolution of hare mtDNA and may have influenced the occurrence and consequences of the many reported cases of massive mtDNA introgression. However, the origin of adaptation remains elusive. PMID:24696399

The Mitochondrial m-AAA Protease Prevents Demyelination and Hair Greying.

PubMed

Wang, Shuaiyu; Jacquemyn, Julie; Murru, Sara; Martinelli, Paola; Barth, Esther; Langer, Thomas; Niessen, Carien M; Rugarli, Elena I

2016-12-01

The m-AAA protease preserves proteostasis of the inner mitochondrial membrane. It ensures a functional respiratory chain, by controlling the turnover of respiratory complex subunits and allowing mitochondrial translation, but other functions in mitochondria are conceivable. Mutations in genes encoding subunits of the m-AAA protease have been linked to various neurodegenerative diseases in humans, such as hereditary spastic paraplegia and spinocerebellar ataxia. While essential functions of the m-AAA protease for neuronal survival have been established, its role in adult glial cells remains enigmatic. Here, we show that deletion of the highly expressed subunit AFG3L2 in mature mouse oligodendrocytes provokes early-on mitochondrial fragmentation and swelling, as previously shown in neurons, but causes only late-onset motor defects and myelin abnormalities. In contrast, total ablation of the m-AAA protease, by deleting both Afg3l2 and its paralogue Afg3l1, triggers progressive motor dysfunction and demyelination, owing to rapid oligodendrocyte cell death. Surprisingly, the mice showed premature hair greying, caused by progressive loss of melanoblasts that share a common developmental origin with Schwann cells and are targeted in our experiments. Thus, while both neurons and glial cells are dependant on the m-AAA protease for survival in vivo, complete ablation of the complex is necessary to trigger death of oligodendrocytes, hinting to cell-autonomous thresholds of vulnerability to m-AAA protease deficiency.

The Mitochondrial Genome and Transcriptome of the Basal Dinoflagellate Hematodinium sp.: Character Evolution within the Highly Derived Mitochondrial Genomes of Dinoflagellates

PubMed Central

Gornik, S. G.; Waller, R. F.

2012-01-01

The sister phyla dinoflagellates and apicomplexans inherited a drastically reduced mitochondrial genome (mitochondrial DNA, mtDNA) containing only three protein-coding (cob, cox1, and cox3) genes and two ribosomal RNA (rRNA) genes. In apicomplexans, single copies of these genes are encoded on the smallest known mtDNA chromosome (6 kb). In dinoflagellates, however, the genome has undergone further substantial modifications, including massive genome amplification and recombination resulting in multiple copies of each gene and gene fragments linked in numerous combinations. Furthermore, protein-encoding genes have lost standard stop codons, trans-splicing of messenger RNAs (mRNAs) is required to generate complete cox3 transcripts, and extensive RNA editing recodes most genes. From taxa investigated to date, it is unclear when many of these unusual dinoflagellate mtDNA characters evolved. To address this question, we investigated the mitochondrial genome and transcriptome character states of the deep branching dinoflagellate Hematodinium sp. Genomic data show that like later-branching dinoflagellates Hematodinium sp. also contains an inflated, heavily recombined genome of multicopy genes and gene fragments. Although stop codons are also lacking for cox1 and cob, cox3 still encodes a conventional stop codon. Extensive editing of mRNAs also occurs in Hematodinium sp. The mtDNA of basal dinoflagellate Hematodinium sp. indicates that much of the mtDNA modification in dinoflagellates occurred early in this lineage, including genome amplification and recombination, and decreased use of standard stop codons. Trans-splicing, on the other hand, occurred after Hematodinium sp. diverged. Only RNA editing presents a nonlinear pattern of evolution in dinoflagellates as this process occurs in Hematodinium sp. but is absent in some later-branching taxa indicating that this process was either lost in some lineages or developed more than once during the evolution of the highly unusual

The mitochondrial genome and transcriptome of the basal dinoflagellate Hematodinium sp.: character evolution within the highly derived mitochondrial genomes of dinoflagellates.

PubMed

Jackson, C J; Gornik, S G; Waller, R F

2012-01-01

The sister phyla dinoflagellates and apicomplexans inherited a drastically reduced mitochondrial genome (mitochondrial DNA, mtDNA) containing only three protein-coding (cob, cox1, and cox3) genes and two ribosomal RNA (rRNA) genes. In apicomplexans, single copies of these genes are encoded on the smallest known mtDNA chromosome (6 kb). In dinoflagellates, however, the genome has undergone further substantial modifications, including massive genome amplification and recombination resulting in multiple copies of each gene and gene fragments linked in numerous combinations. Furthermore, protein-encoding genes have lost standard stop codons, trans-splicing of messenger RNAs (mRNAs) is required to generate complete cox3 transcripts, and extensive RNA editing recodes most genes. From taxa investigated to date, it is unclear when many of these unusual dinoflagellate mtDNA characters evolved. To address this question, we investigated the mitochondrial genome and transcriptome character states of the deep branching dinoflagellate Hematodinium sp. Genomic data show that like later-branching dinoflagellates Hematodinium sp. also contains an inflated, heavily recombined genome of multicopy genes and gene fragments. Although stop codons are also lacking for cox1 and cob, cox3 still encodes a conventional stop codon. Extensive editing of mRNAs also occurs in Hematodinium sp. The mtDNA of basal dinoflagellate Hematodinium sp. indicates that much of the mtDNA modification in dinoflagellates occurred early in this lineage, including genome amplification and recombination, and decreased use of standard stop codons. Trans-splicing, on the other hand, occurred after Hematodinium sp. diverged. Only RNA editing presents a nonlinear pattern of evolution in dinoflagellates as this process occurs in Hematodinium sp. but is absent in some later-branching taxa indicating that this process was either lost in some lineages or developed more than once during the evolution of the highly unusual

Amerindian mitochondrial DNAs have rare Asian mutations at high frequencies, suggesting they derived from four primary maternal lineages.

PubMed Central

Schurr, T G; Ballinger, S W; Gan, Y Y; Hodge, J A; Merriwether, D A; Lawrence, D N; Knowler, W C; Weiss, K M; Wallace, D C

1990-01-01

The mitochondrial DNA (mtDNA) sequence variation of the South American Ticuna, the Central American Maya, and the North American Pima was analyzed by restriction-endonuclease digestion and oligonucleotide hybridization. The analysis revealed that Amerindian populations have high frequencies of mtDNAs containing the rare Asian RFLP HincII morph 6, a rare HaeIII site gain, and a unique AluI site gain. In addition, the Asian-specific deletion between the cytochrome c oxidase subunit II (COII) and tRNA(Lys) genes was also prevalent in both the Pima and the Maya. These data suggest that Amerindian mtDNAs derived from at least four primary maternal lineages, that new tribal-specific variants accumulated as these mtDNAs became distributed throughout the Americas, and that some genetic variation may have been lost when the progenitors of the Ticuna separated from the North and Central American populations. Images Figure 1 PMID:1968708

Myeloperoxidase mRNA detection for lineage determination of leukemic blasts: retrospective analysis.

PubMed

Crisan, D; Anstett, M J

1995-07-01

Myeloperoxidase (MPO) mRNA is an early myeloid marker; its detection in the morphologically and immunophenotypically primitive blasts of acute undifferentiated leukemia (AUL) establishes myeloid lineage and allows reclassification as acute myelogenous leukemia with minimal differentiation (AML-MO). We have previously reported a procedure for MPO mRNA detection by RT-PCR (reverse transcription-polymerase chain reaction) and an adaptation for use of routine hematology smears. This variant procedure allows retrospective analysis of mRNA and is used in the present study to evaluate the lineage of leukemic blasts in seven cases with morphology and cytochemistry consistent with AUL. All hematology smears used in this study were air-dried, unstained or Wright-stained and stored at room temperature for periods varying between 3 days and 2 years. MPO mRNA was detected in six cases, establishing the myeloid lineage of the blasts and the diagnosis of AML-MO. In the remaining case, the blasts were MPO mRNA negative, confirming the diagnosis of AUL. The RT-PCR procedure for retrospective mRNA analysis is useful in the clinical setting, due to its high specificity and sensitivity, speed (less than 24 h), safety (no radioactivity) and convenient use of routine hematology smears; it is particularly attractive in clinical situations when fresh or frozen specimens are no longer available at the time when the need for molecular diagnostics becomes apparent.

Aboriginal Australian mitochondrial genome variation - an increased understanding of population antiquity and diversity

NASA Astrophysics Data System (ADS)

Nagle, Nano; van Oven, Mannis; Wilcox, Stephen; van Holst Pellekaan, Sheila; Tyler-Smith, Chris; Xue, Yali; Ballantyne, Kaye N.; Wilcox, Leah; Papac, Luka; Cooke, Karen; van Oorschot, Roland A. H.; McAllister, Peter; Williams, Lesley; Kayser, Manfred; Mitchell, R. John; Adhikarla, Syama; Adler, Christina J.; Balanovska, Elena; Balanovsky, Oleg; Bertranpetit, Jaume; Clarke, Andrew C.; Comas, David; Cooper, Alan; der Sarkissian, Clio S. I.; Dulik, Matthew C.; Gaieski, Jill B.; Ganeshprasad, Arunkumar; Haak, Wolfgang; Haber, Marc; Hobbs, Angela; Javed, Asif; Jin, Li; Kaplan, Matthew E.; Li, Shilin; Martínez-Cruz, Begoña; Matisoo-Smith, Elizabeth A.; Melé, Marta; Merchant, Nirav C.; Owings, Amanda C.; Parida, Laxmi; Pitchappan, Ramasamy; Platt, Daniel E.; Quintana-Murci, Lluis; Renfrew, Colin; Royyuru, Ajay K.; Santhakumari, Arun Varatharajan; Santos, Fabrício R.; Schurr, Theodore G.; Soodyall, Himla; Soria Hernanz, David F.; Swamikrishnan, Pandikumar; Vilar, Miguel G.; Wells, R. Spencer; Zalloua, Pierre A.; Ziegle, Janet S.

2017-03-01

Aboriginal Australians represent one of the oldest continuous cultures outside Africa, with evidence indicating that their ancestors arrived in the ancient landmass of Sahul (present-day New Guinea and Australia) ~55 thousand years ago. Genetic studies, though limited, have demonstrated both the uniqueness and antiquity of Aboriginal Australian genomes. We have further resolved known Aboriginal Australian mitochondrial haplogroups and discovered novel indigenous lineages by sequencing the mitogenomes of 127 contemporary Aboriginal Australians. In particular, the more common haplogroups observed in our dataset included M42a, M42c, S, P5 and P12, followed by rarer haplogroups M15, M16, N13, O, P3, P6 and P8. We propose some major phylogenetic rearrangements, such as in haplogroup P where we delinked P4a and P4b and redefined them as P4 (New Guinean) and P11 (Australian), respectively. Haplogroup P2b was identified as a novel clade potentially restricted to Torres Strait Islanders. Nearly all Aboriginal Australian mitochondrial haplogroups detected appear to be ancient, with no evidence of later introgression during the Holocene. Our findings greatly increase knowledge about the geographic distribution and phylogenetic structure of mitochondrial lineages that have survived in contemporary descendants of Australia’s first settlers.

Aboriginal Australian mitochondrial genome variation - an increased understanding of population antiquity and diversity.

PubMed

Nagle, Nano; van Oven, Mannis; Wilcox, Stephen; van Holst Pellekaan, Sheila; Tyler-Smith, Chris; Xue, Yali; Ballantyne, Kaye N; Wilcox, Leah; Papac, Luka; Cooke, Karen; van Oorschot, Roland A H; McAllister, Peter; Williams, Lesley; Kayser, Manfred; Mitchell, R John

2017-03-13

Aboriginal Australians represent one of the oldest continuous cultures outside Africa, with evidence indicating that their ancestors arrived in the ancient landmass of Sahul (present-day New Guinea and Australia) ~55 thousand years ago. Genetic studies, though limited, have demonstrated both the uniqueness and antiquity of Aboriginal Australian genomes. We have further resolved known Aboriginal Australian mitochondrial haplogroups and discovered novel indigenous lineages by sequencing the mitogenomes of 127 contemporary Aboriginal Australians. In particular, the more common haplogroups observed in our dataset included M42a, M42c, S, P5 and P12, followed by rarer haplogroups M15, M16, N13, O, P3, P6 and P8. We propose some major phylogenetic rearrangements, such as in haplogroup P where we delinked P4a and P4b and redefined them as P4 (New Guinean) and P11 (Australian), respectively. Haplogroup P2b was identified as a novel clade potentially restricted to Torres Strait Islanders. Nearly all Aboriginal Australian mitochondrial haplogroups detected appear to be ancient, with no evidence of later introgression during the Holocene. Our findings greatly increase knowledge about the geographic distribution and phylogenetic structure of mitochondrial lineages that have survived in contemporary descendants of Australia's first settlers.

Mitochondrial DNA Variant in COX1 Subunit Significantly Alters Energy Metabolism of Geographically Divergent Wild Isolates in Caenorhabditis elegans

PubMed Central

Dingley, Stephen D.; Polyak, Erzsebet; Ostrovsky, Julian; Srinivasan, Satish; Lee, Icksoo; Rosenfeld, Amy B.; Tsukikawa, Mai; Xiao, Rui; Selak, Mary A.; Coon, Joshua J.; Hebert, Alexander S.; Grimsrud, Paul A.; Kwon, Young Joon; Pagliarini, David J.; Gai, Xiaowu; Schurr, Theodore G.; Hüttemann, Maik; Nakamaru-Ogiso, Eiko; Falk, Marni J.

2014-01-01

Mitochondrial DNA (mtDNA) sequence variation can influence the penetrance of complex diseases and climatic adaptation. While studies in geographically defined human populations suggest that mtDNA mutations become fixed when they have conferred metabolic capabilities optimally suited for a specific environment, it has been challenging to definitively assign adaptive functions to specific mtDNA sequence variants in mammals. We investigated whether mtDNA genome variation functionally influences Caenorhabditis elegans wild isolates of distinct mtDNA lineages and geographic origins. We found that, relative to N2 (England) wild-type nematodes, CB4856 wild isolates from a warmer native climate (Hawaii) had a unique p.A12S amino acid substitution in the mtDNA-encoded COX1 core catalytic subunit of mitochondrial complex IV (CIV). Relative to N2, CB4856 worms grown at 20 °C had significantly increased CIV enzyme activity, mitochondrial matrix oxidant burden, and sensitivity to oxidative stress but had significantly reduced lifespan and mitochondrial membrane potential. Interestingly, mitochondrial membrane potential was significantly increased in CB4856 grown at its native temperature of 25 °C. A transmitochondrial cybrid worm strain, chpIR (M, CB4856 > N2), was bred as homoplasmic for the CB4856 mtDNA genome in the N2 nuclear background. The cybrid strain also displayed significantly increased CIV activity, demonstrating that this difference results from the mtDNA-encoded p.A12S variant. However, chpIR (M, CB4856 > N2) worms had significantly reduced median and maximal lifespan relative to CB4856, which may relate to their nuclear– mtDNA genome mismatch. Overall, these data suggest that C. elegans wild isolates of varying geographic origins may adapt to environmental challenges through mtDNA variation to modulate critical aspects of mitochondrial energy metabolism. PMID:24534730

Male lineages in South American native groups: evidence of M19 traveling south.

PubMed

Toscanini, Ulises; Gusmão, Leonor; Berardi, Gabriela; Gomes, Verónica; Amorim, António; Salas, Antonio; Raimondi, Eduardo

2011-10-01

With this study, we aimed to determine the different male ancestral components of two Native American communities from Argentina, namely Toba and Colla. The analysis of 27 Y-chromosome SNPs allowed us to identify seven different haplogroups in both samples. Chromosomes carrying the M3 mutation, which typically defines the Native American haplogroup Q1a3a, were seen most frequently in the Toba community (90%). Conversely, Q1a3a was represented in 34% of the Colla Y-chromosomes, whereas haplogroup R1b1, the main representative of western European populations, exhibited the highest frequency in this population (41%). Different M3 sublineages in the Toba community could be identified by observing point mutations at both DYS385 and M19 loci. A microvariant at DYS385, named 16.1, has been characterized, which helps to further subdivide Q1a3a. It is the first time the M19 mutated allele is described in a population from Argentina. This finding supports the old age of the lineages carrying the M19 mutation, but it contradicts the previous hypothesis that the M19 mutated allele is confined to only two Equatorial-Tucano population groups from the north region of South America. The detection of M19 further south than previously thought allows questioning of the hypothesis that this lineage serves as an example of isolation after colonization. This observation also affirms the strong genetic drift to which Native Americans have been subjected. Moreover, our study illustrates a heterogeneous contribution of Europeans to these populations and supports previous studies showing that most Native American groups were subjected to European admixture that primarily involved immigrant men. Copyright © 2011 Wiley-Liss, Inc.

Phylogeographic Analysis of Mitochondrial DNA in Northern Asian Populations

PubMed Central

Derenko, Miroslava ; Malyarchuk, Boris ; Grzybowski, Tomasz ; Denisova, Galina ; Dambueva, Irina ; Perkova, Maria ; Dorzhu, Choduraa ; Luzina, Faina ; Lee, Hong Kyu ; Vanecek, Tomas ; Villems, Richard ; Zakharov, Ilia 

2007-01-01

To elucidate the human colonization process of northern Asia and human dispersals to the Americas, a diverse subset of 71 mitochondrial DNA (mtDNA) lineages was chosen for complete genome sequencing from the collection of 1,432 control-region sequences sampled from 18 autochthonous populations of northern, central, eastern, and southwestern Asia. On the basis of complete mtDNA sequencing, we have revised the classification of haplogroups A, D2, G1, M7, and I; identified six new subhaplogroups (I4, N1e, G1c, M7d, M7e, and J1b2a); and fully characterized haplogroups N1a and G1b, which were previously described only by the first hypervariable segment (HVS1) sequencing and coding-region restriction-fragment–length polymorphism analysis. Our findings indicate that the southern Siberian mtDNA pool harbors several lineages associated with the Late Upper Paleolithic and/or early Neolithic dispersals from both eastern Asia and southwestern Asia/southern Caucasus. Moreover, the phylogeography of the D2 lineages suggests that southern Siberia is likely to be a geographical source for the last postglacial maximum spread of this subhaplogroup to northern Siberia and that the expansion of the D2b branch occurred in Beringia ∼7,000 years ago. In general, a detailed analysis of mtDNA gene pools of northern Asians provides the additional evidence to rule out the existence of a northern Asian route for the initial human colonization of Asia. PMID:17924343

Positive and purifying selection in mitochondrial genomes of a bird with mitonuclear discordance.

PubMed

Morales, Hernán E; Pavlova, Alexandra; Joseph, Leo; Sunnucks, Paul

2015-06-01

Diversifying selection on metabolic pathways can reduce intraspecific gene flow and promote population divergence. An opportunity to explore this arises from mitonuclear discordance observed in an Australian bird Eopsaltria australis. Across >1500 km, nuclear differentiation is low and latitudinally structured by isolation by distance, whereas two highly divergent, parapatric mitochondrial lineages (>6.6% in ND2) show a discordant longitudinal geographic pattern and experience different climates. Vicariance, incomplete lineage sorting and sex-biased dispersal were shown earlier to be unlikely drivers of the mitonuclear discordance; instead, natural selection on a female-linked trait was the preferred hypothesis. Accordingly, here we tested for signals of positive, divergent selection on mitochondrial genes in E. australis. We used codon models and physicochemical profiles of amino acid replacements to analyse complete mitochondrial genomes of the two mitochondrial lineages in E. australis, its sister species Eopsaltria griseogularis, and outgroups. We found evidence of positive selection on at least five amino acids, encoded by genes of two oxidative phosphorylation pathway complexes NADH dehydrogenase (ND4 and ND4L) and cytochrome bc1 (cyt-b) against a background of widespread purifying selection on all mitochondrial genes. Three of these amino acid replacements were fixed in ND4 of the geographically most widespread E. australis lineage. The other two replacements were fixed in ND4L and cyt-b of the geographically more restricted E. australis lineage. We discuss whether this selection may reflect local environmental adaptation, a by-product of other selective processes, or genetic incompatibilities, and propose how these hypotheses can be tested in future. © 2015 John Wiley & Sons Ltd.

The cyclophilin D/Drp1 axis regulates mitochondrial fission contributing to oxidative stress-induced mitochondrial dysfunctions in SH-SY5Y cells.

PubMed

Xiao, Anqi; Gan, Xueqi; Chen, Ruiqi; Ren, Yanming; Yu, Haiyang; You, Chao

2017-01-29

Oxidative stress plays a central role in the pathogenesis of various neurodegenerative diseases. Increasing evidences have demonstrated that structural abnormalities in mitochondria are involved in oxidative stress related nerve cell damage. And Drp1 plays a critical role in mitochondrial dynamic imbalance insulted by oxidative stress-derived mitochondria. However, the status of mitochondrial fusion and fission pathway and its relationship with mitochondrial properties such as mitochondrial membrane permeability transition pore (mPTP) have not been fully elucidated. Here, we demonstrated for the first time the role of Cyclophilin D (CypD), a crucial component for mPTP formation, in the regulation of mitochondrial dynamics in oxidative stress treated nerve cell. We observed that CypD-mediated phosphorylation of Drp1 and subsequently augmented Drp1 recruitment to mitochondria and shifts mitochondrial dynamics toward excessive fission, which contributes to the mitochondrial structural and functional dysfunctions in oxidative stress-treated nerve cells. CypD depletion or over expression accompanies mitochondrial dynamics/functions recovery or aggravation separately. We also demonstrated first time the link between the CypD to mitochondrial dynamics. Our data offer new insights into the mechanism of mitochondrial dynamics which contribute to the mitochondrial dysfunctions, specifically the role of CypD in Drp1-mediated mitochondrial fission. The protective effect of CsA, or other molecules affecting the function of CypD hold promise as a potential novel therapeutic strategy for governing oxidative stress pathology via mitochondrial pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

Lineage-related cytotoxicity and clonogenic profile of 1,4-benzoquinone-exposed hematopoietic stem and progenitor cells

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

Chow, Paik Wah; Toxicology Laboratory, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur; Abdul Hamid, Zariyantey, E-mail: zyantey@ukm.edu.my

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) are sensitive targets for benzene-induced hematotoxicity and leukemogenesis. The impact of benzene exposure on the complex microenvironment of HSCs and HPCs remains elusive. This study aims to investigate the mechanism linking benzene exposure to targeting HSCs and HPCs using phenotypic and clonogenic analyses. Mouse bone marrow (BM) cells were exposed ex vivo to the benzene metabolite, 1,4-benzoquinone (1,4-BQ), for 24 h. Expression of cellular surface antigens for HSC (Sca-1), myeloid (Gr-1, CD11b), and lymphoid (CD45, CD3e) populations were confirmed by flow cytometry. The clonogenicity of cells was studied using the colony-formingmore » unit (CFU) assay for multilineage (CFU-GM and CFU-GEMM) and single-lineage (CFU-E, BFU-E, CFU-G, and CFU-M) progenitors. 1,4-BQ demonstrated concentration-dependent cytotoxicity in mouse BM cells. The percentage of apoptotic cells increased (p < 0.05) following 1,4-BQ exposure. Exposure to 1,4-BQ showed no significant effect on CD3e{sup +} cells but reduced the total counts of Sca-1{sup +}, CD11b{sup +}, Gr-1{sup +}, and CD45{sup +} cells at 7 and 12 μM (p < 0.05). Furthermore, the CFU assay showed reduced (p < 0.05) clonogenicity in 1,4-BQ-treated cells. 1,4-BQ induced CFU-dependent cytotoxicity by significantly inhibiting colony growth for CFU-E, BFU-E, CFU-G, and CFU-M starting at a low concentration of exposure (5 μM); whereas for the CFU-GM and CFU-GEMM, the inhibition of colony growth was remarkable only at 7 and 12 μM of 1,4-BQ, respectively. Taken together, 1,4-BQ caused lineage-related cytotoxicity in mouse HPCs, demonstrating greater toxicity in single-lineage progenitors than in those of multi-lineage. - Highlights: • We examine 1,4-BQ toxicity targeting mouse hematopoietic cell lineages. • 1,4-BQ induces concentration-dependent cytotoxicity in bone marrow (BM) cells. • 1,4-BQ shows lineage-related toxicity on hematopoietic stem and

Mitochondrial phylogeography of a Beringian relict: the endemic freshwater genus of blackfish Dallia (Esociformes).

PubMed

Campbell, M A; Lopéz, J A

2014-02-01

Mitochondrial genetic variability among populations of the blackfish genus Dallia (Esociformes) across Beringia was examined. Levels of divergence and patterns of geographic distribution of mitochondrial DNA lineages were characterized using phylogenetic inference, median-joining haplotype networks, Bayesian skyline plots, mismatch analysis and spatial analysis of molecular variance (SAMOVA) to infer genealogical relationships and to assess patterns of phylogeography among extant mitochondrial lineages in populations of species of Dallia. The observed variation includes extensive standing mitochondrial genetic diversity and patterns of distinct spatial segregation corresponding to historical and contemporary barriers with minimal or no mixing of mitochondrial haplotypes between geographic areas. Mitochondrial diversity is highest in the common delta formed by the Yukon and Kuskokwim Rivers where they meet the Bering Sea. Other regions sampled in this study host comparatively low levels of mitochondrial diversity. The observed levels of mitochondrial diversity and the spatial distribution of that diversity are consistent with persistence of mitochondrial lineages in multiple refugia through the last glacial maximum. © 2014 The Fisheries Society of the British Isles.

Dynamic evolution of Geranium mitochondrial genomes through multiple horizontal and intracellular gene transfers.

PubMed

Park, Seongjun; Grewe, Felix; Zhu, Andan; Ruhlman, Tracey A; Sabir, Jamal; Mower, Jeffrey P; Jansen, Robert K

2015-10-01

The exchange of genetic material between cellular organelles through intracellular gene transfer (IGT) or between species by horizontal gene transfer (HGT) has played an important role in plant mitochondrial genome evolution. The mitochondrial genomes of Geraniaceae display a number of unusual phenomena including highly accelerated rates of synonymous substitutions, extensive gene loss and reduction in RNA editing. Mitochondrial DNA sequences assembled for 17 species of Geranium revealed substantial reduction in gene and intron content relative to the ancestor of the Geranium lineage. Comparative analyses of nuclear transcriptome data suggest that a number of these sequences have been functionally relocated to the nucleus via IGT. Evidence for rampant HGT was detected in several Geranium species containing foreign organellar DNA from diverse eudicots, including many transfers from parasitic plants. One lineage has experienced multiple, independent HGT episodes, many of which occurred within the past 5.5 Myr. Both duplicative and recapture HGT were documented in Geranium lineages. The mitochondrial genome of Geranium brycei contains at least four independent HGT tracts that are absent in its nearest relative. Furthermore, G. brycei mitochondria carry two copies of the cox1 gene that differ in intron content, providing insight into contrasting hypotheses on cox1 intron evolution. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Mitochondrial impairment increases FL-PINK1 levels by calcium-dependent gene expression☆

PubMed Central

Gómez-Sánchez, Rubén; Gegg, Matthew E.; Bravo-San Pedro, José M.; Niso-Santano, Mireia; Alvarez-Erviti, Lydia; Pizarro-Estrella, Elisa; Gutiérrez-Martín, Yolanda; Alvarez-Barrientos, Alberto; Fuentes, José M.; González-Polo, Rosa Ana; Schapira, Anthony H.V.

2014-01-01

Mutations of the PTEN-induced kinase 1 (PINK1) gene are a cause of autosomal recessive Parkinson's disease (PD). This gene encodes a mitochondrial serine/threonine kinase, which is partly localized to mitochondria, and has been shown to play a role in protecting neuronal cells from oxidative stress and cell death, perhaps related to its role in mitochondrial dynamics and mitophagy. In this study, we report that increased mitochondrial PINK1 levels observed in human neuroblastoma SH-SY5Y cells after carbonyl cyanide m-chlorophelyhydrazone (CCCP) treatment were due to de novo protein synthesis, and not just increased stabilization of full length PINK1 (FL-PINK1). PINK1 mRNA levels were significantly increased by 4-fold after 24 h. FL-PINK1 protein levels at this time point were significantly higher than vehicle-treated, or cells treated with CCCP for 3 h, despite mitochondrial content being decreased by 29%. We have also shown that CCCP dissipated the mitochondrial membrane potential (Δψm) and induced entry of extracellular calcium through L/N-type calcium channels. The calcium chelating agent BAPTA-AM impaired the CCCP-induced PINK1 mRNA and protein expression. Furthermore, CCCP treatment activated the transcription factor c-Fos in a calcium-dependent manner. These data indicate that PINK1 expression is significantly increased upon CCCP-induced mitophagy in a calcium-dependent manner. This increase in expression continues after peak Parkin mitochondrial translocation, suggesting a role for PINK1 in mitophagy that is downstream of ubiquitination of mitochondrial substrates. This sensitivity to intracellular calcium levels supports the hypothesis that PINK1 may also play a role in cellular calcium homeostasis and neuroprotection. PMID:24184327

Mitochondrial Genomes of Kinorhyncha: trnM Duplication and New Gene Orders within Animals.

PubMed

Popova, Olga V; Mikhailov, Kirill V; Nikitin, Mikhail A; Logacheva, Maria D; Penin, Aleksey A; Muntyan, Maria S; Kedrova, Olga S; Petrov, Nikolai B; Panchin, Yuri V; Aleoshin, Vladimir V

2016-01-01

Many features of mitochondrial genomes of animals, such as patterns of gene arrangement, nucleotide content and substitution rate variation are extensively used in evolutionary and phylogenetic studies. Nearly 6,000 mitochondrial genomes of animals have already been sequenced, covering the majority of animal phyla. One of the groups that escaped mitogenome sequencing is phylum Kinorhyncha-an isolated taxon of microscopic worm-like ecdysozoans. The kinorhynchs are thought to be one of the early-branching lineages of Ecdysozoa, and their mitochondrial genomes may be important for resolving evolutionary relations between major animal taxa. Here we present the results of sequencing and analysis of mitochondrial genomes from two members of Kinorhyncha, Echinoderes svetlanae (Cyclorhagida) and Pycnophyes kielensis (Allomalorhagida). Their mitochondrial genomes are circular molecules approximately 15 Kbp in size. The kinorhynch mitochondrial gene sequences are highly divergent, which precludes accurate phylogenetic inference. The mitogenomes of both species encode a typical metazoan complement of 37 genes, which are all positioned on the major strand, but the gene order is distinct and unique among Ecdysozoa or animals as a whole. We predict four types of start codons for protein-coding genes in E. svetlanae and five in P. kielensis with a consensus DTD in single letter code. The mitochondrial genomes of E. svetlanae and P. kielensis encode duplicated methionine tRNA genes that display compensatory nucleotide substitutions. Two distant species of Kinorhyncha demonstrate similar patterns of gene arrangements in their mitogenomes. Both genomes have duplicated methionine tRNA genes; the duplication predates the divergence of two species. The kinorhynchs share a few features pertaining to gene order that align them with Priapulida. Gene order analysis reveals that gene arrangement specific of Priapulida may be ancestral for Scalidophora, Ecdysozoa, and even Protostomia.

Mitochondrial Genomes of Kinorhyncha: trnM Duplication and New Gene Orders within Animals

PubMed Central

Popova, Olga V.; Mikhailov, Kirill V.; Nikitin, Mikhail A.; Logacheva, Maria D.; Penin, Aleksey A.; Muntyan, Maria S.; Kedrova, Olga S.; Petrov, Nikolai B.; Panchin, Yuri V.

2016-01-01

Many features of mitochondrial genomes of animals, such as patterns of gene arrangement, nucleotide content and substitution rate variation are extensively used in evolutionary and phylogenetic studies. Nearly 6,000 mitochondrial genomes of animals have already been sequenced, covering the majority of animal phyla. One of the groups that escaped mitogenome sequencing is phylum Kinorhyncha—an isolated taxon of microscopic worm-like ecdysozoans. The kinorhynchs are thought to be one of the early-branching lineages of Ecdysozoa, and their mitochondrial genomes may be important for resolving evolutionary relations between major animal taxa. Here we present the results of sequencing and analysis of mitochondrial genomes from two members of Kinorhyncha, Echinoderes svetlanae (Cyclorhagida) and Pycnophyes kielensis (Allomalorhagida). Their mitochondrial genomes are circular molecules approximately 15 Kbp in size. The kinorhynch mitochondrial gene sequences are highly divergent, which precludes accurate phylogenetic inference. The mitogenomes of both species encode a typical metazoan complement of 37 genes, which are all positioned on the major strand, but the gene order is distinct and unique among Ecdysozoa or animals as a whole. We predict four types of start codons for protein-coding genes in E. svetlanae and five in P. kielensis with a consensus DTD in single letter code. The mitochondrial genomes of E. svetlanae and P. kielensis encode duplicated methionine tRNA genes that display compensatory nucleotide substitutions. Two distant species of Kinorhyncha demonstrate similar patterns of gene arrangements in their mitogenomes. Both genomes have duplicated methionine tRNA genes; the duplication predates the divergence of two species. The kinorhynchs share a few features pertaining to gene order that align them with Priapulida. Gene order analysis reveals that gene arrangement specific of Priapulida may be ancestral for Scalidophora, Ecdysozoa, and even Protostomia

The Impact of Mitochondrial Complex Inhibition on mESC Differentiation

EPA Science Inventory

The Impact of Mitochondrial Complex Inhibition on mESC Differentiation JE Royland, SH Warren, S Jeffay, MR Hoopes, HP Nichols, ES Hunter U.S. Environmental Protection Agency, Integrated Systems Toxicology Division, Research Triangle Park, NC The importance of mitochondrial funct...

Reconstruction of two colonisation pathways of Mantis religiosa (Mantodea) in Germany using four mitochondrial markers.

PubMed

Linn, Catherine Anne; Griebeler, Eva Maria

2015-02-01

Past and recent climatic changes induced shifts in species ranges. Mantis religiosa has also expanded its range across Germany within the past decades. To determine the ancestry of German M. religiosa we sequenced four mitochondrial genes (COI, COII, Cyt b, ND4) of European M. religiosa populations. We found an east, central and west European lineage of M. religiosa. These distinct lineages are consistent with genetic isolation by distance during glacial periods, and the re-colonization of northern parts of Europe by species from different refugia. Within Germany, we found haplotypes clustering to the central and west European lineage suggesting that M. religiosa immigrated from two directions into Germany. Mismatch distributions, and negative Tajima's D and Fu's Fs values indicate a current range expansion of the central and west European lineage. We hypothesise that ongoing global warming which increases the availability of thermally favourable areas in Germany for M. religiosa adds to its current range expansion. In conclusion, M. religiosa colonized Germany via two directions: west German populations descended from French populations and east German populations from Czech populations.

CypD-mPTP axis regulates mitochondrial functions contributing to osteogenic dysfunction of MC3T3-E1 cells in inflammation.

PubMed

Gan, Xueqi; Zhang, Ling; Liu, Beilei; Zhu, Zhuoli; He, Yuting; Chen, Junsheng; Zhu, Junfei; Yu, Haiyang

2018-04-20

Bone is a dynamic organ, the bone-forming osteoblasts and bone-resorbing osteoclasts form the physiological basis of bone remodeling process. During pathological process of numerous inflammatory diseases, these two aspects are uncoupled and the balance is usually tipped in favor of bone destruction. Evidence suggests that the inflammatory destruction of bone is mainly attributed to oxidative stress and is closely related to mitochondrial dysfunction. The mechanisms underlying osteogenic dysfunction in inflammation still need further investigation. Reactive oxygen species (ROS) is associated with mitochondrial dysfunction and cellular damage. Here, we reported an unexplored role of cyclophilin D (CypD), the major modulator of mitochondrial permeability transition pore (mPTP), and the CypD-mPTP axis in inflammation-induced mitochondrial dysfunction and bone damage. And the protective effects of knocking down CypD by siRNA interference or the addition of cyclosporin A (CsA), an inhibitor of CypD, were evidenced by rescued mitochondrial function and osteogenic function of osteoblast under tumor necrosis factor-α (TNF-α) treatment. These findings provide new insights into the role of CypD-mPTP-dependent mitochondrial pathway in the inflammatory bone injury. The protective effect of CsA or other moleculars affecting the mPTP formation may hold promise as a potential novel therapeutic strategy for inflammation-induced bone damage via mitochondrial pathways.

Autosomal and Mitochondrial Adaptation Following Admixture: A Case Study on the Honeybees of Reunion Island

PubMed Central

Wragg, David; Techer, Maéva Angélique; Canale-Tabet, Kamila; Basso, Benjamin; Bidanel, Jean-Pierre; Labarthe, Emmanuelle; Bouchez, Olivier; Le Conte, Yves; Clémencet, Johanna; Delatte, Hélène

2018-01-01

Abstract The honeybee population of the tropical Reunion Island is a genetic admixture of the Apis mellifera unicolor subspecies, originally described in Madagascar, and of European subspecies, mainly A. m. carnica and A. m. ligustica, regularly imported to the island since the late 19th century. We took advantage of this population to study genetic admixing of the tropical-adapted indigenous and temperate-adapted European genetic backgrounds. Whole genome sequencing of 30 workers and 6 males from Reunion, compared with samples from Europe, Madagascar, Mauritius, Rodrigues, and the Seychelles, revealed the Reunion honeybee population to be composed on an average of 53.2 ± 5.9% A. m. unicolor nuclear genomic background, the rest being mainly composed of A. m. carnica and to a lesser extent A. m. ligustica. In striking contrast to this, only 1 out of the 36 honeybees from Reunion had a mitochondrial genome of European origin, suggesting selection has favored the A. m. unicolor mitotype, which is possibly better adapted to the island’s bioclimate. Local ancestry was determined along the chromosomes for all Reunion samples, and a test for preferential selection for the A. m. unicolor or European background revealed 15 regions significantly associated with the A. m. unicolor lineage and 9 regions with the European lineage. Our results provide insights into the long-term consequences of introducing exotic specimen on the nuclear and mitochondrial genomes of locally adapted populations. PMID:29202174

Few mitochondrial DNA sequences are inserted into the turkey (Meleagris gallopavo) nuclear genome: evolutionary analyses and informativity in the domestic lineage.

PubMed

Schiavo, G; Strillacci, M G; Ribani, A; Bovo, S; Roman-Ponce, S I; Cerolini, S; Bertolini, F; Bagnato, A; Fontanesi, L

2018-06-01

Mitochondrial DNA (mtDNA) insertions have been detected in the nuclear genome of many eukaryotes. These sequences are pseudogenes originated by horizontal transfer of mtDNA fragments into the nuclear genome, producing nuclear DNA sequences of mitochondrial origin (numt). In this study we determined the frequency and distribution of mtDNA-originated pseudogenes in the turkey (Meleagris gallopavo) nuclear genome. The turkey reference genome (Turkey_2.01) was aligned with the reference linearized mtDNA sequence using last. A total of 32 numt sequences (corresponding to 18 numt regions derived by unique insertional events) were identified in the turkey nuclear genome (size ranging from 66 to 1415 bp; identity against the modern turkey mtDNA corresponding region ranging from 62% to 100%). Numts were distributed in nine chromosomes and in one scaffold. They derived from parts of 10 mtDNA protein-coding genes, ribosomal genes, the control region and 10 tRNA genes. Seven numt regions reported in the turkey genome were identified in orthologues positions in the Gallus gallus genome and therefore were present in the ancestral genome that in the Cretaceous originated the lineages of the modern crown Galliformes. Five recently integrated turkey numts were validated by PCR in 168 turkeys of six different domestic populations. None of the analysed numts were polymorphic (i.e. absence of the inserted sequence, as reported in numts of recent integration in other species), suggesting that the reticulate speciation model is not useful for explaining the origin of the domesticated turkey lineage. © 2018 Stichting International Foundation for Animal Genetics.

Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes.

PubMed

Germot, A; Philippe, H; Le Guyader, H

1996-12-10

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukaryotic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochondrial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica. We have now isolated from Trichomonas vaginalis a gene encoding a chaperone protein (HSP70) that in other lineages is addressed to the mitochondrial compartment. The phylogenetic reconstruction unambiguously located this HSP70 within a large set of mitochondrial sequences, itself a sister-group of alpha-purple bacteria. In addition, the T. vaginalis protein exhibits the GDAWV sequence signature, so far exclusively found in mitochondrial HSP70 and in proteobacterial dnaK. Thus mitochondrial endosymbiosis could have occurred earlier than previously assumed. The trichomonad double membrane-bounded organelles, the hydrogenosomes, could have evolved from mitochondria.

Manganese inhibits mitochondrial aconitase: a mechanism of manganese neurotoxicity1

PubMed Central

Zheng, Wei; Ren, Sean; Graziano, Joseph H.

2014-01-01

The symptoms of Mn-induced neurotoxicity resemble those of Parkinson’s diseases. Since iron (Fe) appears to play a pivotal role in pathophysiology of Parkinson’s disease, we set out to test the hypothesis that alterations in Fe-requiring enzymes such as aconitase contribute to Mn-induced neurotoxicity. Mitochondrial fractions prepared from rat brain were preincubated with MnCl2 in vitro, followed by the enzyme assay. Mn treatment significantly inhibited mitochondrial aconitase activity (24% inhibition at 625 μM to 81% at 2.5 mM, p < 0.05). The inhibitory effect was reversible and Mn-concentration dependent, and was reversed by the addition of Fe (0.05–1 mM) to the reaction mixture. In an in vivo chronic Mn exposure model, rats received intraperitoneal injection of 6 mg/kg Mn as MnCl2 once daily for 30 consecutive days. Mn exposure led to a region-specific alteration in total aconitase (i.e., mitochondrial + cytoplasmic): 48.5% reduction of the enzyme activity in frontal cortex (p < 0.01), 33.7% in striatum (p < 0.0963), and 20.6% in substantia nigra (p < 0.139). Chronic Mn exposure increased Mn concentrations in serum, CSF, and brain tissues. The elevation of Mn in all selected brain regions (range between 3.1 and 3.9 fold) was similar in magnitude to that in CSF (3.1 fold) rather than serum (6.1 fold). The present results suggest that Mn alters brain aconitase activity, which may lead to the disruption of mitochondrial energy production and cellular Fe metabolism in the brain. PMID:9675333

PGAM5 regulates PINK1/Parkin-mediated mitophagy via DRP1 in CCCP-induced mitochondrial dysfunction.

PubMed

Park, Yun Sun; Choi, Su Eun; Koh, Hyun Chul

2018-03-01

Mitochondrial dynamics and mitophagy are critical processes for regulating mitochondrial homeostasis. Phosphoglycerate mutase family member 5 (PGAM5) is a mitochondrial protein that plays crucial roles in apoptosis and necroptosis, but the roles of PGAM5 in mitochondrial dynamics and mitophagy remain unclear. In this study, we investigated the role of PGAM5 in carbonyl cyanide m-chlorophenylhydrazone (CCCP)-induced mitochondrial damage and the correlation between mitochondrial dynamics and mitophagy using SH-SY5Y cells. We found that CCCP decreased mitochondrial membrane potential, resulting in mitochondrial dysfunction. CCCP increased PGAM5, dynamin-related protein 1 (DRP1), and optic atrophy 1 (OPA1) expression of the mitochondrial fraction in a time-dependent manner. Knockdown of PGAM5 inhibited DRP1 translocation without a change in OPA1 expression in CCCP-treated cells. Furthermore, knockdown of PGAM5 and DRP1 significantly blocked the increase of PTEN-induced putative protein kinase 1 (PINK1) and Parkin expression in the mitochondrial fraction of CCCP-treated cells. Interestingly, CCCP did not alter PINK1/Parkin expression in the mitochondrial fraction of OPA1 knockdown cells. Inhibiting mitophagy by PGAM5 knockdown accelerated CCCP-induced apoptosis. CCCP treatment also results in PINK1 stabilization on the mitochondrial membrane, which subsequently increases Parkin recruitment from the cytosol to abnormal mitochondria. In addition, we found that CCCP increased the level of mitochondrial LC3II, indicating that Parkin recruitment of PINK1 is a result of mitophagy. We propose that activation of PGAM5 is associated with DRP1 recruitment and PINK1 stabilization, which contribute to the modulation of mitophagy in CCCP-treated cells with mitochondrial dysfunction. In conclusion, we demonstrated that PGAM5 regulates PINK1-Parkin-mediated mitophagy, which can exert a neuroprotective effect against CCCP-induced apoptosis. Copyright © 2017 Elsevier B.V. All rights

Inhibition of mTOR Prevents ROS Production Initiated by Ethidium Bromide-Induced Mitochondrial DNA Depletion

PubMed Central

Nacarelli, Timothy; Azar, Ashley; Sell, Christian

2014-01-01

The regulation of mitochondrial mass and DNA content involves a complex interaction between mitochondrial DNA replication machinery, functional components of the electron transport chain, selective clearance of mitochondria, and nuclear gene expression. In order to gain insight into cellular responses to mitochondrial stress, we treated human diploid fibroblasts with ethidium bromide at concentrations that induced loss of mitochondrial DNA over a period of 7 days. The decrease in mitochondrial DNA was accompanied by a reduction in steady state levels of the mitochondrial DNA binding protein, TFAM, a reduction in several electron transport chain protein levels, increased mitochondrial and total cellular ROS, and activation of p38 MAPK. However, there was an increase in mitochondrial mass and voltage dependent anion channel levels. In addition, mechanistic target of rapamycin (mTOR) activity, as judged by p70S6K targets, was decreased while steady state levels of p62/SQSTM1 and Parkin were increased. Treatment of cells with rapamycin created a situation in which cells were better able to adapt to the mitochondrial dysfunction, resulting in decreased ROS and increased cell viability but did not prevent the reduction in mitochondrial DNA. These effects may be due to a more efficient flux through the electron transport chain, increased autophagy, or enhanced AKT signaling, coupled with a reduced growth rate. Together, the results suggest that mTOR activity is affected by mitochondrial stress, which may be part of the retrograde signal system required for normal mitochondrial homeostasis. PMID:25104948

A heterogeneous population of nuclear-encoded mitochondrial mRNAs is present in the axons of primary sympathetic neurons.

PubMed

Aschrafi, Armaz; Kar, Amar N; Gale, Jenna R; Elkahloun, Abdel G; Vargas, Jose Noberto S; Sales, Naomi; Wilson, Gabriel; Tompkins, Miranda; Gioio, Anthony E; Kaplan, Barry B

2016-09-01

Mitochondria are enriched in subcellular regions of high energy consumption, such as axons and pre-synaptic nerve endings. Accumulating evidence suggests that mitochondrial maintenance in these distal structural/functional domains of the neuron depends on the "in-situ" translation of nuclear-encoded mitochondrial mRNAs. In support of this notion, we recently provided evidence for the axonal targeting of several nuclear-encoded mRNAs, such as cytochrome c oxidase, subunit 4 (COXIV) and ATP synthase, H+ transporting and mitochondrial Fo complex, subunit C1 (ATP5G1). Furthermore, we showed that axonal trafficking and local translation of these mRNAs plays a critical role in the generation of axonal ATP. Using a global gene expression analysis, this study identified a highly diverse population of nuclear-encoded mRNAs that were enriched in the axon and presynaptic nerve terminals. Among this population of mRNAs, fifty seven were found to be at least two-fold more abundant in distal axons, as compared with the parental cell bodies. Gene ontology analysis of the nuclear-encoded mitochondrial mRNAs suggested functions for these gene products in molecular and biological processes, including but not limited to oxidoreductase and electron carrier activity and proton transport. Based on these results, we postulate that local translation of nuclear-encoded mitochondrial mRNAs present in the axons may play an essential role in local energy production and maintenance of mitochondrial function. Published by Elsevier B.V.

Mitochondrial Phylogenomics of Modern and Ancient Equids

PubMed Central

Vilstrup, Julia T.; Seguin-Orlando, Andaine; Stiller, Mathias; Ginolhac, Aurelien; Raghavan, Maanasa; Nielsen, Sandra C. A.; Weinstock, Jacobo; Froese, Duane; Vasiliev, Sergei K.; Ovodov, Nikolai D.; Clary, Joel; Helgen, Kristofer M.; Fleischer, Robert C.; Cooper, Alan; Shapiro, Beth; Orlando, Ludovic

2013-01-01

The genus Equus is richly represented in the fossil record, yet our understanding of taxonomic relationships within this genus remains limited. To estimate the phylogenetic relationships among modern horses, zebras, asses and donkeys, we generated the first data set including complete mitochondrial sequences from all seven extant lineages within the genus Equus. Bayesian and Maximum Likelihood phylogenetic inference confirms that zebras are monophyletic within the genus, and the Plains and Grevy’s zebras form a well-supported monophyletic group. Using ancient DNA techniques, we further characterize the complete mitochondrial genomes of three extinct equid lineages (the New World stilt-legged horses, NWSLH; the subgenus Sussemionus; and the Quagga, Equus quagga quagga). Comparisons with extant taxa confirm the NWSLH as being part of the caballines, and the Quagga and Plains zebras as being conspecific. However, the evolutionary relationships among the non-caballine lineages, including the now-extinct subgenus Sussemionus, remain unresolved, most likely due to extremely rapid radiation within this group. The closest living outgroups (rhinos and tapirs) were found to be too phylogenetically distant to calibrate reliable molecular clocks. Additional mitochondrial genome sequence data, including radiocarbon dated ancient equids, will be required before revisiting the exact timing of the lineage radiation leading up to modern equids, which for now were found to have possibly shared a common ancestor as far as up to 4 Million years ago (Mya). PMID:23437078

Different contributions of ancient mitochondrial and Y-chromosomal lineages in 'Karretjie people' of the Great Karoo in South Africa.

PubMed

Schlebusch, Carina M; de Jongh, Michael; Soodyall, Himla

2011-09-01

The Karretjie people of the South African Great Karoo are itinerants who subsist by sheep shearing. Although officially classified 'Coloured', they are aware of their Khoe and San roots. To investigate the maternal and paternal ancestries of the Karretjie people we analyzed their mitochondrial and Y-chromosome DNA variation. Their genetic ancestry was compared with a neighboring group of 'Coloured' individuals. We found that the mitochondrial DNA (mtDNA) haplogroup L0d was present in all the Karretjie people examined, suggesting a maternal contribution, exclusively from the Khoe and San, whereas the paternal ancestry in males was more heterogeneous. The Coloured sample, on the other hand, were found to have a lower frequency of L0d (64.5%), but did harbor other African (27.6%) and non-African (7.9%) mtDNA haplogroups. Similar to the Karretjie people, the Y-chromosome lineages identified in the Coloured group had heterogeneous origins. This study also enabled an assessment of mtDNA variation within L0d sub-haplogroups. All seven of the L0d sub-clades were identified in the combined sample and were used to construct an L0d network.

Nuclear-Encoded Mitochondrial mRNAs: A Powerful Force in Axonal Growth and Development.

PubMed

Gale, Jenna R; Aschrafi, Armaz; Gioio, Anthony E; Kaplan, Barry B

2018-04-01

Axons, their growth cones, and synaptic nerve terminals are neuronal subcompartments that have high energetic needs. As such, they are enriched in mitochondria, which supply the ATP necessary to meet these demands. To date, a heterogeneous population of nuclear-encoded mitochondrial mRNAs has been identified in distal axons and growth cones. Accumulating evidence suggests that the local translation of these mRNAs is required for mitochondrial maintenance and axonal viability. Here, we review evidence that suggests a critical role for axonal translation of nuclear-encoded mitochondrial mRNAs in axonal growth and development. Additionally, we explore the role that site-specific translation at the mitochondria itself may play in this process. Finally, we briefly review the clinical implications of dysregulation of local translation of mitochondrial-related mRNAs in neurodevelopmental disorders.

Genome Evolution and Innovation across the Four Major Lineages of Cryptococcus gattii.

PubMed

Farrer, Rhys A; Desjardins, Christopher A; Sakthikumar, Sharadha; Gujja, Sharvari; Saif, Sakina; Zeng, Qiandong; Chen, Yuan; Voelz, Kerstin; Heitman, Joseph; May, Robin C; Fisher, Matthew C; Cuomo, Christina A

2015-09-01

Cryptococcus gattii is a fungal pathogen of humans, causing pulmonary infections in otherwise healthy hosts. To characterize genomic variation among the four major lineages of C. gattii (VGI, -II, -III, and -IV), we generated, annotated, and compared 16 de novo genome assemblies, including the first for the rarely isolated lineages VGIII and VGIV. By identifying syntenic regions across assemblies, we found 15 structural rearrangements, which were almost exclusive to the VGI-III-IV lineages. Using synteny to inform orthology prediction, we identified a core set of 87% of C. gattii genes present as single copies in all four lineages. Remarkably, 737 genes are variably inherited across lineages and are overrepresented for response to oxidative stress, mitochondrial import, and metal binding and transport. Specifically, VGI has an expanded set of iron-binding genes thought to be important to the virulence of Cryptococcus, while VGII has expansions in the stress-related heat shock proteins relative to the other lineages. We also characterized genes uniquely absent in each lineage, including a copper transporter absent from VGIV, which influences Cryptococcus survival during pulmonary infection and the onset of meningoencephalitis. Through inclusion of population-level data for an additional 37 isolates, we identified a new transcontinental clonal group that we name VGIIx, mitochondrial recombination between VGII and VGIII, and positive selection of multidrug transporters and the iron-sulfur protein aconitase along multiple branches of the phylogenetic tree. Our results suggest that gene expansion or contraction and positive selection have introduced substantial variation with links to mechanisms of pathogenicity across this species complex. The genetic differences between phenotypically different pathogens provide clues to the underlying mechanisms of those traits and can lead to new drug targets and improved treatments for those diseases. In this paper, we compare 16

Phosphorylation of Mitochondrial Polyubiquitin by PINK1 Promotes Parkin Mitochondrial Tethering

PubMed Central

Shiba-Fukushima, Kahori; Arano, Taku; Matsumoto, Gen; Inoshita, Tsuyoshi; Yoshida, Shigeharu; Ishihama, Yasushi; Ryu, Kwon-Yul; Nukina, Nobuyuki; Hattori, Nobutaka; Imai, Yuzuru

2014-01-01

The kinase PINK1 and the E3 ubiquitin (Ub) ligase Parkin participate in mitochondrial quality control. The phosphorylation of Ser65 in Parkin's ubiquitin-like (UBl) domain by PINK1 stimulates Parkin activation and translocation to damaged mitochondria, which induces mitophagy generating polyUb chain. However, Parkin Ser65 phosphorylation is insufficient for Parkin mitochondrial translocation. Here we report that Ser65 in polyUb chain is also phosphorylated by PINK1, and that phosphorylated polyUb chain on mitochondria tethers Parkin at mitochondria. The expression of Tom70MTS-4xUb SE, which mimics phospho-Ser65 polyUb chains on the mitochondria, activated Parkin E3 activity and its mitochondrial translocation. An E3-dead form of Parkin translocated to mitochondria with reduced membrane potential in the presence of Tom70MTS-4xUb SE, whereas non-phospho-polyUb mutant Tom70MTS-4xUb SA abrogated Parkin translocation. Parkin binds to the phospho-polyUb chain through its RING1-In-Between-RING (IBR) domains, but its RING0-linker is also required for mitochondrial translocation. Moreover, the expression of Tom70MTS-4xUb SE improved mitochondrial degeneration in PINK1-deficient, but not Parkin-deficient, Drosophila. Our study suggests that the phosphorylation of mitochondrial polyUb by PINK1 is implicated in both Parkin activation and mitochondrial translocation, predicting a chain reaction mechanism of mitochondrial phospho-polyUb production by which rapid translocation of Parkin is achieved. PMID:25474007

HLS7, a hemopoietic lineage switch gene homologous to the leukemia-inducing gene MLF1.

PubMed Central

Williams, J H; Daly, L N; Ingley, E; Beaumont, J G; Tilbrook, P A; Lalonde, J P; Stillitano, J P; Klinken, S P

1999-01-01

Hemopoietic lineage switching occurs when leukemic cells, apparently committed to one lineage, change and display the phenotype of another pathway. cDNA representational difference analysis was used to identify myeloid-specific genes that may be associated with an erythroid to myeloid lineage switch involving the murine J2E erythroleukemic cell line. One of the genes isolated (HLS7) is homologous to the novel human oncogene myeloid leukemia factor 1 (MLF1) involved in the t(3;5)(q25.1;q34) translocation associated with acute myeloid leukemia. Enforced expression of HLS7 in J2E cells induced a monoblastoid phenotype, thereby recapitulating the spontaneous erythroid to myeloid lineage switch. HLS7 also inhibited erythropoietin- or chemically-induced differentiation of erythroleukemic cell lines and suppressed development of erythropoietin-responsive colonies in semi-solid culture. However, intracellular signaling activated by erythropoietin was not impeded by ectopic expression of HLS7. In contrast, HLS7 promoted maturation of M1 monoblastoid cells and increased myeloid colony formation in vitro. These data show that HLS7 can influence erythroid/myeloid lineage switching and the development of normal hemopoietic cells. PMID:10523300

HLS7, a hemopoietic lineage switch gene homologous to the leukemia-inducing gene MLF1.

PubMed

Williams, J H; Daly, L N; Ingley, E; Beaumont, J G; Tilbrook, P A; Lalonde, J P; Stillitano, J P; Klinken, S P

1999-10-15

Hemopoietic lineage switching occurs when leukemic cells, apparently committed to one lineage, change and display the phenotype of another pathway. cDNA representational difference analysis was used to identify myeloid-specific genes that may be associated with an erythroid to myeloid lineage switch involving the murine J2E erythroleukemic cell line. One of the genes isolated (HLS7) is homologous to the novel human oncogene myeloid leukemia factor 1 (MLF1) involved in the t(3;5)(q25.1;q34) translocation associated with acute myeloid leukemia. Enforced expression of HLS7 in J2E cells induced a monoblastoid phenotype, thereby recapitulating the spontaneous erythroid to myeloid lineage switch. HLS7 also inhibited erythropoietin- or chemically-induced differentiation of erythroleukemic cell lines and suppressed development of erythropoietin-responsive colonies in semi-solid culture. However, intracellular signaling activated by erythropoietin was not impeded by ectopic expression of HLS7. In contrast, HLS7 promoted maturation of M1 monoblastoid cells and increased myeloid colony formation in vitro. These data show that HLS7 can influence erythroid/myeloid lineage switching and the development of normal hemopoietic cells.

Insulin and IGF-1 improve mitochondrial function in a PI-3K/Akt-dependent manner and reduce mitochondrial generation of reactive oxygen species in Huntington's disease knock-in striatal cells.

PubMed

Ribeiro, Márcio; Rosenstock, Tatiana R; Oliveira, Ana M; Oliveira, Catarina R; Rego, A Cristina

2014-09-01

Oxidative stress and mitochondrial dysfunction have been described in Huntington's disease, a disorder caused by expression of mutant huntingtin (mHtt). IGF-1 was previously shown to protect HD cells, whereas insulin prevented neuronal oxidative stress. In this work we analyzed the role of insulin and IGF-1 in striatal cells derived from HD knock-in mice on mitochondrial production of reactive oxygen species (ROS) and related antioxidant and signaling pathways influencing mitochondrial function. Insulin and IGF-1 decreased mitochondrial ROS induced by mHtt and normalized mitochondrial SOD activity, without affecting intracellular glutathione levels. IGF-1 and insulin promoted Akt phosphorylation without changing the nuclear levels of phosphorylated Nrf2 or Nrf2/ARE activity. Insulin and IGF-1 treatment also decreased mitochondrial Drp1 phosphorylation, suggesting reduced mitochondrial fragmentation, and ameliorated mitochondrial function in HD cells in a PI-3K/Akt-dependent manner. This was accompanied by increased total and phosphorylated Akt, Tfam, and mitochondrial-encoded cytochrome c oxidase II, as well as Tom20 and Tom40 in mitochondria of insulin- and IGF-1-treated mutant striatal cells. Concomitantly, insulin/IGF-1-treated mutant cells showed reduced apoptotic features. Hence, insulin and IGF-1 improve mitochondrial function and reduce mitochondrial ROS caused by mHtt by activating the PI-3K/Akt signaling pathway, in a process independent of Nrf2 transcriptional activity, but involving enhanced mitochondrial levels of Akt and mitochondrial-encoded complex IV subunit. Copyright © 2014 Elsevier Inc. All rights reserved.

Ancient wolf lineages in India.

PubMed Central

Sharma, Dinesh K; Maldonado, Jesus E; Jhala, Yadrendradev V; Fleischer, Robert C

2004-01-01

All previously obtained wolf (Canis lupus) and dog (Canis familiaris) mitochondrial (mt) DNA sequences fall within an intertwined and shallow clade (the 'wolf-dog' clade). We sequenced mtDNA of recent and historical samples from 45 wolves from throughout lowland peninsular India and 23 wolves from the Himalayas and Tibetan Plateau and compared these sequences with all available wolf and dog sequences. All 45 lowland Indian wolves have one of four closely related haplotypes that form a well-supported, divergent sister lineage to the wolf-dog clade. This unique lineage may have been independent for more than 400,000 years. Although seven Himalayan wolves from western and central Kashmir fall within the widespread wolf-dog clade, one from Ladakh in eastern Kashmir, nine from Himachal Pradesh, four from Nepal and two from Tibet form a very different basal clade. This lineage contains five related haplotypes that probably diverged from other canids more than 800,000 years ago, but we find no evidence of current barriers to admixture. Thus, the Indian subcontinent has three divergent, ancient and apparently parapatric mtDNA lineages within the morphologically delineated wolf. No haplotypes of either novel lineage are found within a sample of 37 Indian (or other) dogs. Thus, we find no evidence that these two taxa played a part in the domestication of canids. PMID:15101402

Ancient wolf lineages in India.

PubMed

Sharma, Dinesh K; Maldonado, Jesus E; Jhala, Yadrendradev V; Fleischer, Robert C

2004-02-07

All previously obtained wolf (Canis lupus) and dog (Canis familiaris) mitochondrial (mt) DNA sequences fall within an intertwined and shallow clade (the 'wolf-dog' clade). We sequenced mtDNA of recent and historical samples from 45 wolves from throughout lowland peninsular India and 23 wolves from the Himalayas and Tibetan Plateau and compared these sequences with all available wolf and dog sequences. All 45 lowland Indian wolves have one of four closely related haplotypes that form a well-supported, divergent sister lineage to the wolf-dog clade. This unique lineage may have been independent for more than 400,000 years. Although seven Himalayan wolves from western and central Kashmir fall within the widespread wolf-dog clade, one from Ladakh in eastern Kashmir, nine from Himachal Pradesh, four from Nepal and two from Tibet form a very different basal clade. This lineage contains five related haplotypes that probably diverged from other canids more than 800,000 years ago, but we find no evidence of current barriers to admixture. Thus, the Indian subcontinent has three divergent, ancient and apparently parapatric mtDNA lineages within the morphologically delineated wolf. No haplotypes of either novel lineage are found within a sample of 37 Indian (or other) dogs. Thus, we find no evidence that these two taxa played a part in the domestication of canids.

A novel mitochondrial carrier protein Mme1 acts as a yeast mitochondrial magnesium exporter.

PubMed

Cui, Yixian; Zhao, Shanke; Wang, Juan; Wang, Xudong; Gao, Bingquan; Fan, Qiangwang; Sun, Fei; Zhou, Bing

2015-03-01

The homeostasis of magnesium (Mg2+), an abundant divalent cation indispensable for many biological processes including mitochondrial functions, is underexplored. Previously, two mitochondrial Mg2+ importers, Mrs2 and Lpe10, were characterized for mitochondrial Mg2+ uptake. We now show that mitochondrial Mg2+ homeostasis is accurately controlled through the combined effects of previously known importers and a novel exporter, Mme1 (mitochondrial magnesium exporter 1). Mme1 belongs to the mitochondrial carrier family and was isolated for its mutation that is able to suppress the mrs2Δ respiration defect. Deletion of MME1 significantly increased steady-state mitochondrial Mg2+ concentration, while overexpression decreased it. Measurements of Mg2+ exit from proteoliposomes reconstituted with purified Mme1 provided definite evidence for Mme1 as an Mg2+ exporter. Our studies identified, for the first time, a mitochondrial Mg2+ exporter that works together with mitochondrial importers to ensure the precise control of mitochondrial Mg2+ homeostasis. Copyright © 2015 Elsevier B.V. All rights reserved.

mSEL-1L (Suppressor/Enhancer Lin12-like) Protein Levels Influence Murine Neural Stem Cell Self-renewal and Lineage Commitment*

PubMed Central

Cardano, Marina; Diaferia, Giuseppe R.; Cattaneo, Monica; Dessì, Sara S.; Long, Qiaoming; Conti, Luciano; DeBlasio, Pasquale; Cattaneo, Elena; Biunno, Ida

2011-01-01

Murine SEL-1L (mSEL-1L) is a key component of the endoplasmic reticulum-associated degradation pathway. It is essential during development as revealed by the multi-organ dysfunction and in uterus lethality occurring in homozygous mSEL-1L-deficient mice. Here we show that mSEL-1L is highly expressed in pluripotent embryonic stem cells and multipotent neural stem cells (NSCs) but silenced in all mature neural derivatives (i.e. astrocytes, oligodendrocytes, and neurons) by mmu-miR-183. NSCs derived from homozygous mSEL-1L-deficient embryos (mSEL-1L−/− NSCs) fail to proliferate in vitro, show a drastic reduction of the Notch effector HES-5, and reveal a significant down-modulation of the early neural progenitor markers PAX-6 and OLIG-2, when compared with the wild type (mSEL-1L+/+ NSCs) counterpart. Furthermore, these cells are almost completely deprived of the neural marker Nestin, display a significant decrease of SOX-2 expression, and rapidly undergo premature astrocytic commitment and apoptosis. The data suggest severe self-renewal defects occurring in these cells probably mediated by misregulation of the Notch signaling. The results reported here denote mSEL-1L as a primitive marker with a possible involvement in the regulation of neural progenitor stemness maintenance and lineage determination. PMID:21454627

mSEL-1L (Suppressor/enhancer Lin12-like) protein levels influence murine neural stem cell self-renewal and lineage commitment.

PubMed

Cardano, Marina; Diaferia, Giuseppe R; Cattaneo, Monica; Dessì, Sara S; Long, Qiaoming; Conti, Luciano; Deblasio, Pasquale; Cattaneo, Elena; Biunno, Ida

2011-05-27

Murine SEL-1L (mSEL-1L) is a key component of the endoplasmic reticulum-associated degradation pathway. It is essential during development as revealed by the multi-organ dysfunction and in uterus lethality occurring in homozygous mSEL-1L-deficient mice. Here we show that mSEL-1L is highly expressed in pluripotent embryonic stem cells and multipotent neural stem cells (NSCs) but silenced in all mature neural derivatives (i.e. astrocytes, oligodendrocytes, and neurons) by mmu-miR-183. NSCs derived from homozygous mSEL-1L-deficient embryos (mSEL-1L(-/-) NSCs) fail to proliferate in vitro, show a drastic reduction of the Notch effector HES-5, and reveal a significant down-modulation of the early neural progenitor markers PAX-6 and OLIG-2, when compared with the wild type (mSEL-1L(+/+) NSCs) counterpart. Furthermore, these cells are almost completely deprived of the neural marker Nestin, display a significant decrease of SOX-2 expression, and rapidly undergo premature astrocytic commitment and apoptosis. The data suggest severe self-renewal defects occurring in these cells probably mediated by misregulation of the Notch signaling. The results reported here denote mSEL-1L as a primitive marker with a possible involvement in the regulation of neural progenitor stemness maintenance and lineage determination.

Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes

PubMed Central

Germot, Agnès; Philippe, Hervé; Le Guyader, Hervé

1996-01-01

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukaryotic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochondrial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica. We have now isolated from Trichomonas vaginalis a gene encoding a chaperone protein (HSP70) that in other lineages is addressed to the mitochondrial compartment. The phylogenetic reconstruction unambiguously located this HSP70 within a large set of mitochondrial sequences, itself a sister-group of α-purple bacteria. In addition, the T. vaginalis protein exhibits the GDAWV sequence signature, so far exclusively found in mitochondrial HSP70 and in proteobacterial dnaK. Thus mitochondrial endosymbiosis could have occurred earlier than previously assumed. The trichomonad double membrane-bounded organelles, the hydrogenosomes, could have evolved from mitochondria. PMID:8962101

Cofilin1-dependent actin dynamics control DRP1-mediated mitochondrial fission

PubMed Central

Rehklau, Katharina; Hoffmann, Lena; Gurniak, Christine B; Ott, Martin; Witke, Walter; Scorrano, Luca; Culmsee, Carsten; Rust, Marco B

2017-01-01

Mitochondria form highly dynamic networks in which organelles constantly fuse and divide. The relevance of mitochondrial dynamics is evident from its implication in various human pathologies, including cancer or neurodegenerative, endocrine and cardiovascular diseases. Dynamin-related protein 1 (DRP1) is a key regulator of mitochondrial fission that oligomerizes at the mitochondrial outer membrane and hydrolyzes GTP to drive mitochondrial fragmentation. Previous studies demonstrated that DRP1 recruitment and mitochondrial fission is promoted by actin polymerization at the mitochondrial surface, controlled by the actin regulatory proteins inverted formin 2 (INF2) and Spire1C. These studies suggested the requirement of additional actin regulatory activities to control DRP1-mediated mitochondrial fission. Here we show that the actin-depolymerizing protein cofilin1, but not its close homolog actin-depolymerizing factor (ADF), is required to maintain mitochondrial morphology. Deletion of cofilin1 caused mitochondrial DRP1 accumulation and fragmentation, without altering mitochondrial function or other organelles’ morphology. Mitochondrial morphology in cofilin1-deficient cells was restored upon (i) re-expression of wild-type cofilin1 or a constitutively active mutant, but not of an actin-binding-deficient mutant, (ii) pharmacological destabilization of actin filaments and (iii) genetic depletion of DRP1. Our work unraveled a novel function for cofilin1-dependent actin dynamics in mitochondrial fission, and identified cofilin1 as a negative regulator of mitochondrial DRP1 activity. We conclude that cofilin1 is required for local actin dynamics at mitochondria, where it may balance INF2/Spire1C-induced actin polymerization. PMID:28981113

Genetic Diversity and Differentiation in Urban and Indigenous Populations of Mexico: Patterns of Mitochondrial DNA and Y-Chromosome Lineages.

PubMed

González-Sobrino, Blanca Z; Pintado-Cortina, Ana P; Sebastián-Medina, Leticia; Morales-Mandujano, Fabiola; Contreras, Alejandra V; Aguilar, Yasnaya E; Chávez-Benavides, Juan; Carrillo-Rodríguez, Aurelio; Silva-Zolezzi, Irma; Medrano-González, Luis

2016-01-01

Aside from the admixture between indigenous people and people from overseas, populations in Mexico changed drastically after the Spanish conquest of the sixteenth century, forming an intricate history that has been underutilized in understanding the genetic population structure of Mexicans. To infer historical processes of isolation, dispersal, and assimilation, we examined the phylogeography of mitochondrial (mt) DNA and Y-chromosome lineages in 3,026 individuals from 10 urban and nine indigenous populations by identifying single nucleotide polymorphisms. A geographic array with a predominance of Amerindian lineages was observed for mtDNA, with northern indigenous populations being divergent from the central and southern indigenous populations; urban populations showed low differentiation with isolation by distance. Y-chromosome variation distinguished urban and indigenous populations through the Amerindian haplogroup Q frequency. The MtDNA and the Y-chromosome together primarily distinguished urban and indigenous populations, with different geographic arrays for both. Gene flow across geographical distance and between the urban and indigenous realms appears to have altered the pre-Hispanic phylogeography in central and southern Mexico, mainly by displacement of women, while maintaining the indigenous isolation in the north, southeast, and Zapotec regions. Most Amerindian mtDNA diversity currently occurs in urban populations and appears to be reduced among indigenous people.

Early myeloid lineage choice is not initiated by random PU.1 to GATA1 protein ratios.

PubMed

Hoppe, Philipp S; Schwarzfischer, Michael; Loeffler, Dirk; Kokkaliaris, Konstantinos D; Hilsenbeck, Oliver; Moritz, Nadine; Endele, Max; Filipczyk, Adam; Gambardella, Adriana; Ahmed, Nouraiz; Etzrodt, Martin; Coutu, Daniel L; Rieger, Michael A; Marr, Carsten; Strasser, Michael K; Schauberger, Bernhard; Burtscher, Ingo; Ermakova, Olga; Bürger, Antje; Lickert, Heiko; Nerlov, Claus; Theis, Fabian J; Schroeder, Timm

2016-07-14

The mechanisms underlying haematopoietic lineage decisions remain disputed. Lineage-affiliated transcription factors with the capacity for lineage reprogramming, positive auto-regulation and mutual inhibition have been described as being expressed in uncommitted cell populations. This led to the assumption that lineage choice is cell-intrinsically initiated and determined by stochastic switches of randomly fluctuating cross-antagonistic transcription factors. However, this hypothesis was developed on the basis of RNA expression data from snapshot and/or population-averaged analyses. Alternative models of lineage choice therefore cannot be excluded. Here we use novel reporter mouse lines and live imaging for continuous single-cell long-term quantification of the transcription factors GATA1 and PU.1 (also known as SPI1). We analyse individual haematopoietic stem cells throughout differentiation into megakaryocytic-erythroid and granulocytic-monocytic lineages. The observed expression dynamics are incompatible with the assumption that stochastic switching between PU.1 and GATA1 precedes and initiates megakaryocytic-erythroid versus granulocytic-monocytic lineage decision-making. Rather, our findings suggest that these transcription factors are only executing and reinforcing lineage choice once made. These results challenge the current prevailing model of early myeloid lineage choice.

A Role for Mitochondrial Phosphoenolpyruvate Carboxykinase (PEPCK-M) in the Regulation of Hepatic Gluconeogenesis*

PubMed Central

Stark, Romana; Guebre-Egziabher, Fitsum; Zhao, Xiaojian; Feriod, Colleen; Dong, Jianying; Alves, Tiago C.; Ioja, Simona; Pongratz, Rebecca L.; Bhanot, Sanjay; Roden, Michael; Cline, Gary W.; Shulman, Gerald I.; Kibbey, Richard G.

2014-01-01

Synthesis of phosphoenolpyruvate (PEP) from oxaloacetate is an absolute requirement for gluconeogenesis from mitochondrial substrates. Generally, this reaction has solely been attributed to the cytosolic isoform of PEPCK (PEPCK-C), although loss of the mitochondrial isoform (PEPCK-M) has never been assessed. Despite catalyzing the same reaction, to date the only significant role reported in mammals for the mitochondrial isoform is as a glucose sensor necessary for insulin secretion. We hypothesized that this nutrient-sensing mitochondrial GTP-dependent pathway contributes importantly to gluconeogenesis. PEPCK-M was acutely silenced in gluconeogenic tissues of rats using antisense oligonucleotides both in vivo and in isolated hepatocytes. Silencing PEPCK-M lowers plasma glucose, insulin, and triglycerides, reduces white adipose, and depletes hepatic glycogen, but raises lactate. There is a switch of gluconeogenic substrate preference to glycerol that quantitatively accounts for a third of glucose production. In contrast to the severe mitochondrial deficiency characteristic of PEPCK-C knock-out livers, hepatocytes from PEPCK-M-deficient livers maintained normal oxidative function. Consistent with its predicted role, gluconeogenesis rates from hepatocytes lacking PEPCK-M are severely reduced for lactate, alanine, and glutamine, but not for pyruvate and glycerol. Thus, PEPCK-M has a direct role in fasted and fed glucose homeostasis, and this mitochondrial GTP-dependent pathway should be reconsidered for its involvement in both normal and diabetic metabolism. PMID:24497630

A role for mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) in the regulation of hepatic gluconeogenesis.

PubMed

Stark, Romana; Guebre-Egziabher, Fitsum; Zhao, Xiaojian; Feriod, Colleen; Dong, Jianying; Alves, Tiago C; Ioja, Simona; Pongratz, Rebecca L; Bhanot, Sanjay; Roden, Michael; Cline, Gary W; Shulman, Gerald I; Kibbey, Richard G

2014-03-14

Synthesis of phosphoenolpyruvate (PEP) from oxaloacetate is an absolute requirement for gluconeogenesis from mitochondrial substrates. Generally, this reaction has solely been attributed to the cytosolic isoform of PEPCK (PEPCK-C), although loss of the mitochondrial isoform (PEPCK-M) has never been assessed. Despite catalyzing the same reaction, to date the only significant role reported in mammals for the mitochondrial isoform is as a glucose sensor necessary for insulin secretion. We hypothesized that this nutrient-sensing mitochondrial GTP-dependent pathway contributes importantly to gluconeogenesis. PEPCK-M was acutely silenced in gluconeogenic tissues of rats using antisense oligonucleotides both in vivo and in isolated hepatocytes. Silencing PEPCK-M lowers plasma glucose, insulin, and triglycerides, reduces white adipose, and depletes hepatic glycogen, but raises lactate. There is a switch of gluconeogenic substrate preference to glycerol that quantitatively accounts for a third of glucose production. In contrast to the severe mitochondrial deficiency characteristic of PEPCK-C knock-out livers, hepatocytes from PEPCK-M-deficient livers maintained normal oxidative function. Consistent with its predicted role, gluconeogenesis rates from hepatocytes lacking PEPCK-M are severely reduced for lactate, alanine, and glutamine, but not for pyruvate and glycerol. Thus, PEPCK-M has a direct role in fasted and fed glucose homeostasis, and this mitochondrial GTP-dependent pathway should be reconsidered for its involvement in both normal and diabetic metabolism.

Mitochondrial Evolution

PubMed Central

Gray, Michael W.

2012-01-01

Viewed through the lens of the genome it contains, the mitochondrion is of unquestioned bacterial ancestry, originating from within the bacterial phylum α-Proteobacteria (Alphaproteobacteria). Accordingly, the endosymbiont hypothesis—the idea that the mitochondrion evolved from a bacterial progenitor via symbiosis within an essentially eukaryotic host cell—has assumed the status of a theory. Yet mitochondrial genome evolution has taken radically different pathways in diverse eukaryotic lineages, and the organelle itself is increasingly viewed as a genetic and functional mosaic, with the bulk of the mitochondrial proteome having an evolutionary origin outside Alphaproteobacteria. New data continue to reshape our views regarding mitochondrial evolution, particularly raising the question of whether the mitochondrion originated after the eukaryotic cell arose, as assumed in the classical endosymbiont hypothesis, or whether this organelle had its beginning at the same time as the cell containing it. PMID:22952398

Diversity of the Arabidopsis mitochondrial genome occurs via nuclear-controlled recombination activity.

PubMed

Arrieta-Montiel, Maria P; Shedge, Vikas; Davila, Jaime; Christensen, Alan C; Mackenzie, Sally A

2009-12-01

The plant mitochondrial genome is recombinogenic, with DNA exchange activity controlled to a large extent by nuclear gene products. One nuclear gene, MSH1, appears to participate in suppressing recombination in Arabidopsis at every repeated sequence ranging in size from 108 to 556 bp. Present in a wide range of plant species, these mitochondrial repeats display evidence of successful asymmetric DNA exchange in Arabidopsis when MSH1 is disrupted. Recombination frequency appears to be influenced by repeat sequence homology and size, with larger size repeats corresponding to increased DNA exchange activity. The extensive mitochondrial genomic reorganization of the msh1 mutant produced altered mitochondrial transcription patterns. Comparison of mitochondrial genomes from the Arabidopsis ecotypes C24, Col-0, and Ler suggests that MSH1 activity accounts for most or all of the polymorphisms distinguishing these genomes, producing ecotype-specific stoichiometric changes in each line. Our observations suggest that MSH1 participates in mitochondrial genome evolution by influencing the lineage-specific pattern of mitochondrial genetic variation in higher plants.

Carriers of mitochondrial DNA macrohaplogroup L3 basal lineages migrated back to Africa from Asia around 70,000 years ago.

PubMed

Cabrera, Vicente M; Marrero, Patricia; Abu-Amero, Khaled K; Larruga, Jose M

2018-06-19

The main unequivocal conclusion after three decades of phylogeographic mtDNA studies is the African origin of all extant modern humans. In addition, a southern coastal route has been argued for to explain the Eurasian colonization of these African pioneers. Based on the age of macrohaplogroup L3, from which all maternal Eurasian and the majority of African lineages originated, the out-of-Africa event has been dated around 60-70 kya. On the opposite side, we have proposed a northern route through Central Asia across the Levant for that expansion and, consistent with the fossil record, we have dated it around 125 kya. To help bridge differences between the molecular and fossil record ages, in this article we assess the possibility that mtDNA macrohaplogroup L3 matured in Eurasia and returned to Africa as basal L3 lineages around 70 kya. The coalescence ages of all Eurasian (M,N) and African (L3 ) lineages, both around 71 kya, are not significantly different. The oldest M and N Eurasian clades are found in southeastern Asia instead near of Africa as expected by the southern route hypothesis. The split of the Y-chromosome composite DE haplogroup is very similar to the age of mtDNA L3. An Eurasian origin and back migration to Africa has been proposed for the African Y-chromosome haplogroup E. Inside Africa, frequency distributions of maternal L3 and paternal E lineages are positively correlated. This correlation is not fully explained by geographic or ethnic affinities. This correlation rather seems to be the result of a joint and global replacement of the old autochthonous male and female African lineages by the new Eurasian incomers. These results are congruent with a model proposing an out-of-Africa migration into Asia, following a northern route, of early anatomically modern humans carrying pre-L3 mtDNA lineages around 125 kya, subsequent diversification of pre-L3 into the basal lineages of L3, a return to Africa of Eurasian fully modern humans around 70 kya

A novel fission-independent role of dynamin-related protein 1 in cardiac mitochondrial respiration

PubMed Central

Zhang, Huiliang; Wang, Pei; Bisetto, Sara; Yoon, Yisang; Chen, Quan; Sheu, Shey-Shing; Wang, Wang

2017-01-01

Aims Mitochondria in adult cardiomyocytes exhibit static morphology and infrequent dynamic changes, despite the high abundance of fission and fusion regulatory proteins in the heart. Previous reports have indicated that fusion proteins may bear functions beyond morphology regulation. Here, we investigated the role of fission protein, dynamin-related protein 1 (DRP1), on mitochondrial respiration regulation in adult cardiomyocytes. Methods and results By using genetic or pharmacological approaches, we manipulated the activity or protein level of fission and fusion proteins and found they mildly influenced mitochondrial morphology in adult rodent cardiomyocytes, which is in contrast to their significant effect in H9C2 cardiac myoblasts. Intriguingly, inhibiting endogenous DRP1 by dominant-negative DRP1 mutation (K38A), shRNA, or Mdivi-1 suppressed maximal respiration and respiratory control ratio in isolated mitochondria from adult mouse heart or in adult cardiomyocytes from rat. Meanwhile, basal respiration was increased due to increased proton leak. Facilitating mitofusin-mediated fusion by S3 compound, however, failed to inhibit mitochondrial respiration in adult cardiomyocytes. Mechanistically, DRP1 inhibition did not affect the maximal activity of individual respiratory chain complexes or the assembly of supercomplexes. Knocking out cyclophilin D, a regulator of mitochondrial permeability transition pore (mPTP), abolished the effect of DRP1 inhibition on respiration. Finally, DRP1 inhibition decreased transient mPTP-mediated mitochondrial flashes, delayed laser-induced mPTP opening and suppressed mitochondrial reactive oxygen species (ROS). Conclusion These results uncover a novel non-canonical function of the fission protein, DRP1 in maintaining or positively stimulating mitochondrial respiration, bioenergetics and ROS signalling in adult cardiomyocyte, which is likely independent of morphological changes. PMID:27794519

Distinct Mechanisms of Pathogenic DJ-1 Mutations in Mitochondrial Quality Control

PubMed Central

Strobbe, Daniela; Robinson, Alexis A.; Harvey, Kirsten; Rossi, Lara; Ferraina, Caterina; de Biase, Valerio; Rodolfo, Carlo; Harvey, Robert J.; Campanella, Michelangelo

2018-01-01

The deglycase and chaperone protein DJ-1 is pivotal for cellular oxidative stress responses and mitochondrial quality control. Mutations in PARK7, encoding DJ-1, are associated with early-onset familial Parkinson’s disease and lead to pathological oxidative stress and/or disrupted protein degradation by the proteasome. The aim of this study was to gain insights into the pathogenic mechanisms of selected DJ-1 missense mutations, by characterizing protein–protein interactions, core parameters of mitochondrial function, quality control regulation via autophagy, and cellular death following dopamine accumulation. We report that the DJ-1M26I mutant influences DJ-1 interactions with SUMO-1, in turn enhancing removal of mitochondria and conferring increased cellular susceptibility to dopamine toxicity. By contrast, the DJ-1D149A mutant does not influence mitophagy, but instead impairs Ca2+ dynamics and free radical homeostasis by disrupting DJ-1 interactions with a mitochondrial accessory protein known as DJ-1-binding protein (DJBP/EFCAB6). Thus, individual DJ-1 mutations have different effects on mitochondrial function and quality control, implying mutation-specific pathomechanisms converging on impaired mitochondrial homeostasis. PMID:29599708

Dengue virus induces mitochondrial elongation through impairment of Drp1-triggered mitochondrial fission

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

Barbier, Vincent; Lang, Diane; Valois, Sierra

Mitochondria are highly dynamic organelles that undergo continuous cycles of fission and fusion to maintain essential cellular functions. An imbalance between these two processes can result in many pathophysiological outcomes. Dengue virus (DENV) interacts with cellular organelles, including mitochondria, to successfully replicate in cells. This study used live-cell imaging and found an increase in mitochondrial length and respiration during DENV infection. The level of mitochondrial fission protein, Dynamin-related protein 1 (Drp1), was decreased on mitochondria during DENV infection, as well as Drp1 phosphorylated on serine 616, which is important for mitochondrial fission. DENV proteins NS4b and NS3 were also associatedmore » with subcellular fractions of mitochondria. Induction of fission through uncoupling of mitochondria or overexpression of Drp1 wild-type and Drp1 with a phosphomimetic mutation (S616D) significantly reduced viral replication. These results demonstrate that DENV infection causes an imbalance in mitochondrial dynamics by inhibiting Drp1-triggered mitochondrial fission, which promotes viral replication. - Highlights: •Mitochondrial length and respiration are increased during DENV infection. •DENV inhibits Drp1-triggered mitochondrial fission. •DENV titers are reduced by mitochondrial fragmentation, Drp1 WT and S616D expression. •Viral proteins NS4b and NS3 are associated with subcellular fractions of mitochondria.« less

Parkin suppresses Drp1-independent mitochondrial division.

PubMed

Roy, Madhuparna; Itoh, Kie; Iijima, Miho; Sesaki, Hiromi

2016-07-01

The cycle of mitochondrial division and fusion disconnect and reconnect individual mitochondria in cells to remodel this energy-producing organelle. Although dynamin-related protein 1 (Drp1) plays a major role in mitochondrial division in cells, a reduced level of mitochondrial division still persists even in the absence of Drp1. It is unknown how much Drp1-mediated mitochondrial division accounts for the connectivity of mitochondria. The role of a Parkinson's disease-associated protein-parkin, which biochemically and genetically interacts with Drp1-in mitochondrial connectivity also remains poorly understood. Here, we quantified the number and connectivity of mitochondria using mitochondria-targeted photoactivatable GFP in cells. We show that the loss of Drp1 increases the connectivity of mitochondria by 15-fold in mouse embryonic fibroblasts (MEFs). While a single loss of parkin does not affect the connectivity of mitochondria, the connectivity of mitochondria significantly decreased compared with a single loss of Drp1 when parkin was lost in the absence of Drp1. Furthermore, the loss of parkin decreased the frequency of depolarization of the mitochondrial inner membrane that is caused by increased mitochondrial connectivity in Drp1-knockout MEFs. Therefore, our data suggest that parkin negatively regulates Drp1-indendent mitochondrial division. Copyright © 2016 Elsevier Inc. All rights reserved.

Targeting of cytosolic mRNA to mitochondria: naked RNA can bind to the mitochondrial surface.

PubMed

Michaud, Morgane; Maréchal-Drouard, Laurence; Duchêne, Anne-Marie

2014-05-01

Mitochondria contain hundreds of proteins but only a few are encoded by the mitochondrial genome. The other proteins are nuclear-encoded and imported into mitochondria. These proteins can be translated on free cytosolic polysomes, then targeted and imported into mitochondria. Nonetheless, numerous cytosolic mRNAs encoding mitochondrial proteins are detected at the surface of mitochondria in yeast, plants and animals. The localization of mRNAs to the vicinity of mitochondria would be a way for mitochondrial protein sorting. The mechanisms responsible for mRNA targeting to mitochondria are not clearly identified. Sequences within the mRNA molecules (cis-elements), as well as a few trans-acting factors, have been shown to be essential for targeting of some mRNAs. In order to identify receptors involved in mRNA docking to the mitochondrial surface, we have developed an in vitro mRNA binding assay with isolated plant mitochondria. We show that naked mRNAs are able to bind to isolated mitochondria, and our results strongly suggest that mRNA docking to the plant mitochondrial outer membrane requires at least one component of TOM complex. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

T-cell-restricted intracellular antigen 1 facilitates mitochondrial fragmentation by enhancing the expression of mitochondrial fission factor

PubMed Central

Tak, Hyosun; Eun, Jung Woo; Kim, Jihye; Park, So Jung; Kim, Chongtae; Ji, Eunbyul; Lee, Heejin; Kang, Hoin; Cho, Dong-Hyung; Lee, Kyungbun; Kim, Wook; Nam, Suk Woo; Lee, Eun Kyung

2017-01-01

Mitochondrial morphology is dynamically regulated by the formation of small fragmented units or interconnected mitochondrial networks, and this dynamic morphological change is a pivotal process in normal mitochondrial function. In the present study, we identified a novel regulator responsible for the regulation of mitochondrial dynamics. An assay using CHANG liver cells stably expressing mitochondrial-targeted yellow fluorescent protein (mtYFP) and a group of siRNAs revealed that T-cell intracellular antigen protein-1 (TIA-1) affects mitochondrial morphology by enhancing mitochondrial fission. The function of TIA-1 in mitochondrial dynamics was investigated through various biological approaches and expression analysis in human specimen. Downregulation of TIA-1-enhanced mitochondrial elongation, whereas ectopic expression of TIA-1 resulted in mitochondria fragmentation. In addition, TIA-1 increased mitochondrial activity, including the rate of ATP synthesis and oxygen consumption. Further, we identified mitochondrial fission factor (MFF) as a direct target of TIA-1, and showed that TIA-1 promotes mitochondrial fragmentation by enhancing MFF translation. TIA-1 null cells had a decreased level of MFF and less mitochondrial Drp1, a critical factor for mitochondrial fragmentation, thereby enhancing mitochondrial elongation. Taken together, our results indicate that TIA-1 is a novel factor that facilitates mitochondrial dynamics by enhancing MFF expression and contributes to mitochondrial dysfunction. PMID:27612012

Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells

PubMed Central

Doczi, Judit; Torocsik, Beata; Echaniz-Laguna, Andoni; Mousson de Camaret, Bénédicte; Starkov, Anatoly; Starkova, Natalia; Gál, Aniko; Molnár, Mária J; Kawamata, Hibiki; Manfredi, Giovanni; Adam-Vizi, Vera; Chinopoulos, Christos

2016-01-01

The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT’s voltage-sensing properties elicited by calcimycin or H2O2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the ‘thinness ratio’ and the ‘cobalt-calcein’ technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca2+ levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H2O2-induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient. PMID:27221760

Molecular characterisation of dengue virus type 1 reveals lineage replacement during circulation in Brazilian territory.

PubMed

Carneiro, Adriana Ribeiro; Cruz, Ana Cecília Ribeiro; Vallinoto, Marcelo; Melo, Diego de Vasconcelos; Ramos, Rommel Thiago J; Medeiros, Daniele Barbosa Almeida; Silva, Eliana Vieira Pinto da; Vasconcelos, Pedro Fernando da Costa

2012-09-01

Dengue fever is the most important arbovirus infection found in tropical regions around the world. Dispersal of the vector and an increase in migratory flow between countries have led to large epidemics and severe clinical outcomes, such as dengue haemorrhagic fever and dengue shock syndrome. This study analysed the genetic variability of the dengue virus serotype 1 (DENV-1) in Brazil with regard to the full-length structural genes C/prM/M/E among 34 strains isolated during epidemics that occurred in the country between 1994-2011. Virus phylogeny and time of divergence were also evaluated with only the E gene of the strains isolated from 1994-2008. An analysis of amino acid differences between these strains and the French Guiana strain (FGA/89) revealed the presence of important nonsynonymous substitutions in the amino acid sequences, including residues E297 (Met→Thr) and E338 (Ser→Leu). A phylogenetic analysis of E proteins comparing the studied isolates and other strains selected from the GenBank database showed that the Brazilian DENV-1 strains since 1982 belonged to genotype V. This analysis also showed that different introductions of strains from the 1990s represented lineage replacement, with the identification of three lineages that cluster all isolates from the Americas. An analysis of the divergence time of DENV-1 indicated that the lineage circulating in Brazil emerged from an ancestral lineage that originated approximately 44.35 years ago.

A novel fission-independent role of dynamin-related protein 1 in cardiac mitochondrial respiration.

PubMed

Zhang, Huiliang; Wang, Pei; Bisetto, Sara; Yoon, Yisang; Chen, Quan; Sheu, Shey-Shing; Wang, Wang

2017-02-01

Mitochondria in adult cardiomyocytes exhibit static morphology and infrequent dynamic changes, despite the high abundance of fission and fusion regulatory proteins in the heart. Previous reports have indicated that fusion proteins may bear functions beyond morphology regulation. Here, we investigated the role of fission protein, dynamin-related protein 1 (DRP1), on mitochondrial respiration regulation in adult cardiomyocytes. By using genetic or pharmacological approaches, we manipulated the activity or protein level of fission and fusion proteins and found they mildly influenced mitochondrial morphology in adult rodent cardiomyocytes, which is in contrast to their significant effect in H9C2 cardiac myoblasts. Intriguingly, inhibiting endogenous DRP1 by dominant-negative DRP1 mutation (K38A), shRNA, or Mdivi-1 suppressed maximal respiration and respiratory control ratio in isolated mitochondria from adult mouse heart or in adult cardiomyocytes from rat. Meanwhile, basal respiration was increased due to increased proton leak. Facilitating mitofusin-mediated fusion by S3 compound, however, failed to inhibit mitochondrial respiration in adult cardiomyocytes. Mechanistically, DRP1 inhibition did not affect the maximal activity of individual respiratory chain complexes or the assembly of supercomplexes. Knocking out cyclophilin D, a regulator of mitochondrial permeability transition pore (mPTP), abolished the effect of DRP1 inhibition on respiration. Finally, DRP1 inhibition decreased transient mPTP-mediated mitochondrial flashes, delayed laser-induced mPTP opening and suppressed mitochondrial reactive oxygen species (ROS). These results uncover a novel non-canonical function of the fission protein, DRP1 in maintaining or positively stimulating mitochondrial respiration, bioenergetics and ROS signalling in adult cardiomyocyte, which is likely independent of morphological changes. Published on behalf of the European Society of Cardiology. All rights reserved. © The

A Comparative Analysis of Mitochondrial ORFans: New Clues on Their Origin and Role in Species with Doubly Uniparental Inheritance of Mitochondria

PubMed Central

Milani, Liliana; Ghiselli, Fabrizio; Guerra, Davide; Breton, Sophie; Passamonti, Marco

2013-01-01

Despite numerous comparative mitochondrial genomics studies revealing that animal mitochondrial genomes are highly conserved in terms of gene content, supplementary genes are sometimes found, often arising from gene duplication. Mitochondrial ORFans (ORFs having no detectable homology and unknown function) were found in bivalve molluscs with Doubly Uniparental Inheritance (DUI) of mitochondria. In DUI animals, two mitochondrial lineages are present: one transmitted through females (F-type) and the other through males (M-type), each showing a specific and conserved ORF. The analysis of 34 mitochondrial major Unassigned Regions of Musculista senhousia F- and M-mtDNA allowed us to verify the presence of novel mitochondrial ORFs in this species and to compare them with ORFs from other species with ascertained DUI, with other bivalves and with animals showing new mitochondrial elements. Overall, 17 ORFans from nine species were analyzed for structure and function. Many clues suggest that the analyzed ORFans arose from endogenization of viral genes. The co-option of such novel genes by viral hosts may have determined some evolutionary aspects of host life cycle, possibly involving mitochondria. The structure similarity of DUI ORFans within evolutionary lineages may also indicate that they originated from independent events. If these novel ORFs are in some way linked to DUI establishment, a multiple origin of DUI has to be considered. These putative proteins may have a role in the maintenance of sperm mitochondria during embryo development, possibly masking them from the degradation processes that normally affect sperm mitochondria in species with strictly maternal inheritance. PMID:23824218

A comparative analysis of mitochondrial ORFans: new clues on their origin and role in species with doubly uniparental inheritance of mitochondria.

PubMed

Milani, Liliana; Ghiselli, Fabrizio; Guerra, Davide; Breton, Sophie; Passamonti, Marco

2013-01-01

Despite numerous comparative mitochondrial genomics studies revealing that animal mitochondrial genomes are highly conserved in terms of gene content, supplementary genes are sometimes found, often arising from gene duplication. Mitochondrial ORFans (ORFs having no detectable homology and unknown function) were found in bivalve molluscs with Doubly Uniparental Inheritance (DUI) of mitochondria. In DUI animals, two mitochondrial lineages are present: one transmitted through females (F-type) and the other through males (M-type), each showing a specific and conserved ORF. The analysis of 34 mitochondrial major Unassigned Regions of Musculista senhousia F- and M-mtDNA allowed us to verify the presence of novel mitochondrial ORFs in this species and to compare them with ORFs from other species with ascertained DUI, with other bivalves and with animals showing new mitochondrial elements. Overall, 17 ORFans from nine species were analyzed for structure and function. Many clues suggest that the analyzed ORFans arose from endogenization of viral genes. The co-option of such novel genes by viral hosts may have determined some evolutionary aspects of host life cycle, possibly involving mitochondria. The structure similarity of DUI ORFans within evolutionary lineages may also indicate that they originated from independent events. If these novel ORFs are in some way linked to DUI establishment, a multiple origin of DUI has to be considered. These putative proteins may have a role in the maintenance of sperm mitochondria during embryo development, possibly masking them from the degradation processes that normally affect sperm mitochondria in species with strictly maternal inheritance.

DJ-1 KNOCK-DOWN IMPAIRS ASTROCYTE MITOCHONDRIAL FUNCTION

PubMed Central

LARSEN, N. J.; AMBROSI, G.; MULLETT, S. J.; BERMAN, S. B.; HINKLE, D. A.

2012-01-01

Mitochondrial dysfunction has long been implicated in the pathogenesis of Parkinson’s disease (PD). PD brain tissues show evidence for mitochondrial respiratory chain Complex I deficiency. Pharmacological inhibitors of Complex I, such as rotenone, cause experimental parkinsonism. The cytoprotective protein DJ-1, whose deletion is sufficient to cause genetic PD, is also known to have mitochondria-stabilizing properties. We have previously shown that DJ-1 is over-expressed in PD astrocytes, and that DJ-1 deficiency impairs the capacity of astrocytes to protect co-cultured neurons against rotenone. Since DJ-1 modulated, astrocyte-mediated neuroprotection against rotenone may depend upon proper astrocytic mitochondrial functioning, we hypothesized that DJ-1 deficiency would impair astrocyte mitochondrial motility, fission/fusion dynamics, membrane potential maintenance, and respiration, both at baseline and as an enhancement of rotenone-induced mitochondrial dysfunction. In astrocyte-enriched cultures, we observed that DJ-1 knock-down reduced mitochondrial motility primarily in the cellular processes of both untreated and rotenone treated cells. In these same cultures, DJ-1 knock-down did not appreciably affect mitochondrial fission, fusion, or respiration, but did enhance rotenone-induced reductions in the mitochondrial membrane potential. In neuron–astrocyte co-cultures, astrocytic DJ-1 knock-down reduced astrocyte process mitochondrial motility in untreated cells, but this effect was not maintained in the presence of rotenone. In the same co-cultures, astrocytic DJ-1 knock-down significantly reduced mitochondrial fusion in the astrocyte cell bodies, but not the processes, under the same conditions of rotenone treatment in which DJ-1 deficiency is known to impair astrocyte-mediated neuroprotection. Our studies therefore demonstrated the following new findings: (i) DJ-1 deficiency can impair astrocyte mitochondrial physiology at multiple levels, (ii) astrocyte

Analysis of functional domains of rat mitochondrial Fis1, the mitochondrial fission-stimulating protein

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

Jofuku, Akihiro; Ishihara, Naotada; Mihara, Katsuyoshi

2005-07-29

In yeast, mitochondrial-fission is regulated by the cytosolic dynamin-like GTPase (Dnm1p) in conjunction with a peripheral protein, Mdv1p, and a C-tail-anchored outer membrane protein, Fis1p. In mammals, a dynamin-related protein (Drp1) and Fis1 are involved in the mitochondrial-fission reaction as Dnm1 and Fis1 orthologues, respectively. The involvement of other component(s), such as the Mdv1 homologue, and the mechanisms regulating mitochondrial-fission remain unclear. Here, we identified rat Fis1 (rFis1) and analyzed its structure-function relationship. Blue-native-polyacrylamide gel electrophoresis revealed that rFis1 formed a {approx}200-kDa complex in the outer mitochondrial membrane. Its expression in HeLa cells promoted extensive mitochondrial fragmentation, and gene knock-downmore » by RNAi induced extension of the mitochondrial networks. Taking advantage of these properties, we analyzed functional domains of rFis1. These experiments revealed that the N-terminal and C-terminal segments are both essential for oligomeric rFis1 interaction, and the middle TPR-like domains regulate proper oligomer assembly. Any mutations that disturb the proper oligomeric assembly compromise mitochondrial division-stimulating activity of rFis1.« less

Mitochondrial Division Inhibitor 1 (mdivi-1) Protects Neurons against Excitotoxicity through the Modulation of Mitochondrial Function and Intracellular Ca2+ Signaling.

PubMed

Ruiz, Asier; Alberdi, Elena; Matute, Carlos

2018-01-01

Excessive dynamin related protein 1 (Drp1)-triggered mitochondrial fission contributes to apoptosis under pathological conditions and therefore it has emerged as a promising therapeutic target. Mitochondrial division inhibitor 1 (mdivi-1) inhibits Drp1-dependent mitochondrial fission and is neuroprotective in several models of brain ischemia and neurodegeneration. However, mdivi-1 also modulates mitochondrial function and oxidative stress independently of Drp1, and consequently the mechanisms through which it protects against neuronal injury are more complex than previously foreseen. In this study, we have analyzed the effects of mdivi-1 on mitochondrial dynamics, Ca 2+ signaling, mitochondrial bioenergetics and cell viability during neuronal excitotoxicity in vitro . Time-lapse fluorescence microscopy revealed that mdivi-1 blocked NMDA-induced mitochondrial fission but not that triggered by sustained AMPA receptor activation, showing that mdivi-1 inhibits excitotoxic mitochondrial fragmentation in a source specific manner. Similarly, mdivi-1 strongly reduced NMDA-triggered necrotic-like neuronal death and, to a lesser extent, AMPA-induced toxicity. Interestingly, neuroprotection provided by mdivi-1 against NMDA, but not AMPA, correlated with a reduction in cytosolic Ca 2+ ([Ca 2+ ] cyt ) overload and calpain activation indicating additional cytoprotective mechanisms. Indeed, mdivi-1 depolarized mitochondrial membrane and depleted ER Ca 2+ content, leading to attenuation of mitochondrial [Ca 2+ ] increase and enhancement of the integrated stress response (ISR) during NMDA receptor activation. Finally, lentiviral knockdown of Drp1 did not rescue NMDA-induced mitochondrial fission and toxicity, indicating that neuroprotective activity of mdivi-1 is Drp1-independent. Together, these results suggest that mdivi-1 induces a Drp1-independent protective phenotype that prevents predominantly NMDA receptor-mediated excitotoxicity through the modulation of mitochondrial

Functional reconstitution of the mitochondrial Ca2+/H+ antiporter Letm1.

PubMed

Tsai, Ming-Feng; Jiang, Dawei; Zhao, Linlin; Clapham, David; Miller, Christopher

2014-01-01

The leucine zipper, EF hand-containing transmembrane protein 1 (Letm1) gene encodes a mitochondrial inner membrane protein, whose depletion severely perturbs mitochondrial Ca(2+) and K(+) homeostasis. Here we expressed, purified, and reconstituted human Letm1 protein in liposomes. Using Ca(2+) fluorophore and (45)Ca(2+)-based assays, we demonstrate directly that Letm1 is a Ca(2+) transporter, with apparent affinities of cations in the sequence of Ca(2+) ≈ Mn(2+) > Gd(3+) ≈ La(3+) > Sr(2+) > Ba(2+), Mg(2+), K(+), Na(+). Kinetic analysis yields a Letm1 turnover rate of 2 Ca(2+)/s and a Km of ∼25 µM. Further experiments show that Letm1 mediates electroneutral 1 Ca(2+)/2 H(+) antiport. Letm1 is insensitive to ruthenium red, an inhibitor of the mitochondrial calcium uniporter, and CGP-37157, an inhibitor of the mitochondrial Na(+)/Ca(2+) exchanger. Functional properties of Letm1 described here are remarkably similar to those of the H(+)-dependent Ca(2+) transport mechanism identified in intact mitochondria.

Evolution of gastropod mitochondrial genome arrangements

PubMed Central

2008-01-01

Background Gastropod mitochondrial genomes exhibit an unusually great variety of gene orders compared to other metazoan mitochondrial genome such as e.g those of vertebrates. Hence, gastropod mitochondrial genomes constitute a good model system to study patterns, rates, and mechanisms of mitochondrial genome rearrangement. However, this kind of evolutionary comparative analysis requires a robust phylogenetic framework of the group under study, which has been elusive so far for gastropods in spite of the efforts carried out during the last two decades. Here, we report the complete nucleotide sequence of five mitochondrial genomes of gastropods (Pyramidella dolabrata, Ascobulla fragilis, Siphonaria pectinata, Onchidella celtica, and Myosotella myosotis), and we analyze them together with another ten complete mitochondrial genomes of gastropods currently available in molecular databases in order to reconstruct the phylogenetic relationships among the main lineages of gastropods. Results Comparative analyses with other mollusk mitochondrial genomes allowed us to describe molecular features and general trends in the evolution of mitochondrial genome organization in gastropods. Phylogenetic reconstruction with commonly used methods of phylogenetic inference (ME, MP, ML, BI) arrived at a single topology, which was used to reconstruct the evolution of mitochondrial gene rearrangements in the group. Conclusion Four main lineages were identified within gastropods: Caenogastropoda, Vetigastropoda, Patellogastropoda, and Heterobranchia. Caenogastropoda and Vetigastropoda are sister taxa, as well as, Patellogastropoda and Heterobranchia. This result rejects the validity of the derived clade Apogastropoda (Caenogastropoda + Heterobranchia). The position of Patellogastropoda remains unclear likely due to long-branch attraction biases. Within Heterobranchia, the most heterogeneous group of gastropods, neither Euthyneura (because of the inclusion of P. dolabrata) nor Pulmonata

Aluminium induced oxidative stress results in decreased mitochondrial biogenesis via modulation of PGC-1α expression

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

Sharma, Deep Raj; Sunkaria, Aditya; Wani, Willayat Yousuf

The present investigation was carried out to elucidate a possible molecular mechanism related to the effects of aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of Peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α) and its downstream targets i.e. Nuclear respiratory factor-1(NRF-1), Nuclear respiratory factor-2(NRF-2) and Mitochondrial transcription factor A (Tfam) in mitochondrial biogenesis. Aluminium lactate (10 mg/kg b.wt./day) was administered intragastrically to rats for 12 weeks. After 12 weeks of exposure, we found an increase in ROS levels, mitochondrial DNA oxidation and decrease in citrate synthase activity in the Hippocampus (HC) andmore » Corpus striatum (CS) regions of rat brain. On the other hand, there was a decrease in the mRNA levels of the mitochondrial encoded subunits–NADH dehydrogenase (ND) subunits i.e. ND1, ND2, ND3, Cytochrome b (Cytb), Cytochrome oxidase (COX) subunits i.e. COX1, COX3, ATP synthase (ATPase) subunit 6 along with reduced expression of nuclear encoded subunits COX4, COX5A, COX5B of Electron transport chain (ETC). Besides, a decrease in mitochondrial DNA copy number and mitochondrial content in both regions of rat brain was observed. The PGC-1α was down-regulated in aluminium treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α in aluminium treated rats. Electron microscopy results revealed a significant increase in the mitochondrial swelling, loss of cristae, chromatin condensation and decreases in mitochondrial number in case of aluminium treated rats as compared to control. So, PGC-1α seems to be a potent target for aluminium neurotoxicity, which makes it an almost ideal target to control or limit the damage that has been associated with the defective mitochondrial function seen in neurodegenerative diseases. - Highlights: • Aluminium decreases the mRNA levels of mitochondrial and nuclear

Phenformin-Induced Mitochondrial Dysfunction Sensitizes Hepatocellular Carcinoma for Dual Inhibition of mTOR.

PubMed

Veiga, Sonia Rosa; Ge, Xuemei; Mercer, Carol A; Hernández-Alvarez, María Isabel; Thomas, Hala Elnakat; Hernández-Losa, Javier; Ramón Y Cajal, Santiago; Zorzano, Antonio; Thomas, George; Kozma, Sara C

2018-04-24

Hepatocellular carcinoma (HCC) ranks second in cancer mortality and has limited therapeutic options. We recently described the synergistic effect of allosteric and ATP-site competitive inhibitors against the mammalian target of rapamycin (mTOR) for the treatment of HCC. However, such inhibitors induce glycemia and increase mitochondrial efficiency. Here we determined whether the mitochondrial complex I inhibitor Phenformin could reverse both side effects, impose an energetic-stress on cancer cells and suppress the growth of HCC. Human HCC cell lines were used in vitro to access the signaling and energetic impact of mTOR inhibitors and Phenformin, either alone or in combination. Next, the therapeutic utility of these drugs alone or in combination was investigated pre-clinically in human orthotopic tumors implanted in mice, by analyzing their impact on the tumor burden and overall survival. We found Phenformin caused mitochondrial dysfunction and fragmentation, inducing a compensatory shift to glycolysis. In contrast, dual inhibition of mTOR impaired cell growth and glycolysis, while increasing mitochondrial fusion and efficiency. In a mouse model of human HCC, dual inhibition of mTOR, together with Phenformin, was highly efficacious in controlling tumor burden. However, more striking, pretreatment with Phenformin sensitized tumors to dual inhibition of mTOR, leading to a dramatic improvement in survival. Treatment of HCC cells in vitro with the biguanide Phenformin causes a metabolic shift to glycolysis, mitochondrial dysfunction and fragmentation, and dramatically sensitizes orthotopic liver tumors to dual inhibition of mTOR. We therefore propose this therapeutic approach should be tested clinically in HCC. Copyright ©2018, American Association for Cancer Research.

Mitochondrial diversity and phylogeography of Acrossocheilus paradoxus (Teleostei: Cyprinidae).

PubMed

Ju, Yu-Min; Hsu, Kui-Ching; Yang, Jin-Quan; Wu, Jui-Hsien; Li, Shan; Wang, Wei-Kuang; Ding, Fang; Li, Jun; Lin, Hung-Du

2018-01-31

Mitochondrial DNA cytochrome b sequences (1141 bp) in 229 specimens of Acrossocheilus paradoxus from 26 populations were identified as four lineages. The pairwise genetic distances among these four lineages ranged from 1.57 to 2.37% (mean= 2.00%). Statistical dispersal-vicariance analysis suggests that the ancestral populations were distributed over mainland China and Northern and Western Taiwan. Approximate Bayesian computation approaches show that the three lineages in Taiwan originated from the lineage in mainland China through three colonization routes during two glaciations. The results indicated that during the glaciation and inter-glacial periods, the Taiwan Strait was exposed and sank, which contributed to the dispersion and differentiation of populations. Furthermore, the populations of A. paradoxus colonized Taiwan through a land bridge to the north of the Formosa Bank, and the Miaoli Plateau in Taiwan was an important barrier that limited gene exchange between populations on both the sides.

Highly divergent mussel lineages in isolated Indonesian marine lakes.

PubMed

Becking, Leontine E; de Leeuw, Christiaan A; Knegt, Bram; Maas, Diede L; de Voogd, Nicole J; Abdunnur; Suyatna, Iwan; Peijnenburg, Katja T C A

2016-01-01

Marine lakes, with populations in landlocked seawater and clearly delineated contours, have the potential to provide a unique model to study early stages of evolution in coastal marine taxa. Here we ask whether populations of the mussel Brachidontes from marine lakes in Berau, East Kalimantan (Indonesia) are isolated from each other and from the coastal mangrove systems. We analyzed sequence data of one mitochondrial marker (Cytochrome Oxidase I (COI)), and two nuclear markers (18S and 28S). In addition, we examined shell shape using a geometric morphometric approach. The Indonesian populations of Brachidontes spp. harbored four deeply diverged lineages (14-75% COI corrected net sequence divergence), two of which correspond to previously recorded lineages from marine lakes in Palau, 1,900 km away. These four lineages also showed significant differences in shell shape and constitute a species complex of at least four undescribed species. Each lake harbored a different lineage despite the fact that the lakes are separated from each other by only 2-6 km, while the two mangrove populations, at 20 km distance from each other, harbored the same lineage and shared haplotypes. Marine lakes thus represent isolated habitats. As each lake contained unique within lineage diversity (0.1-0.2%), we suggest that this may have resulted from in situ divergence due to isolation of founder populations after the formation of the lakes (6,000-12,000 years before present). Combined effects of stochastic processes, local adaptation and increased evolutionary rates could produce high levels of differentiation in small populations such as in marine lake environments. Such short-term isolation at small spatial scales may be an important contributing factor to the high marine biodiversity that is found in the Indo-Australian Archipelago.

Highly divergent mussel lineages in isolated Indonesian marine lakes

PubMed Central

de Leeuw, Christiaan A.; Knegt, Bram; Maas, Diede L.; de Voogd, Nicole J.; Abdunnur; Suyatna, Iwan; Peijnenburg, Katja T.C.A.

2016-01-01

Marine lakes, with populations in landlocked seawater and clearly delineated contours, have the potential to provide a unique model to study early stages of evolution in coastal marine taxa. Here we ask whether populations of the mussel Brachidontes from marine lakes in Berau, East Kalimantan (Indonesia) are isolated from each other and from the coastal mangrove systems. We analyzed sequence data of one mitochondrial marker (Cytochrome Oxidase I (COI)), and two nuclear markers (18S and 28S). In addition, we examined shell shape using a geometric morphometric approach. The Indonesian populations of Brachidontes spp. harbored four deeply diverged lineages (14–75% COI corrected net sequence divergence), two of which correspond to previously recorded lineages from marine lakes in Palau, 1,900 km away. These four lineages also showed significant differences in shell shape and constitute a species complex of at least four undescribed species. Each lake harbored a different lineage despite the fact that the lakes are separated from each other by only 2–6 km, while the two mangrove populations, at 20 km distance from each other, harbored the same lineage and shared haplotypes. Marine lakes thus represent isolated habitats. As each lake contained unique within lineage diversity (0.1–0.2%), we suggest that this may have resulted from in situdivergence due to isolation of founder populations after the formation of the lakes (6,000–12,000 years before present). Combined effects of stochastic processes, local adaptation and increased evolutionary rates could produce high levels of differentiation in small populations such as in marine lake environments. Such short-term isolation at small spatial scales may be an important contributing factor to the high marine biodiversity that is found in the Indo-Australian Archipelago. PMID:27761314

Animal Mitochondrial DNA as We Do Not Know It: mt-Genome Organization and Evolution in Nonbilaterian Lineages

PubMed Central

Pett, Walker

2016-01-01

Abstract Animal mitochondrial DNA (mtDNA) is commonly described as a small, circular molecule that is conserved in size, gene content, and organization. Data collected in the last decade have challenged this view by revealing considerable diversity in animal mitochondrial genome organization. Much of this diversity has been found in nonbilaterian animals (phyla Cnidaria, Ctenophora, Placozoa, and Porifera), which, from a phylogenetic perspective, form the main branches of the animal tree along with Bilateria. Within these groups, mt-genomes are characterized by varying numbers of both linear and circular chromosomes, extra genes (e.g. atp9, polB, tatC), large variation in the number of encoded mitochondrial transfer RNAs (tRNAs) (0–25), at least seven different genetic codes, presence/absence of introns, tRNA and mRNA editing, fragmented ribosomal RNA genes, translational frameshifting, highly variable substitution rates, and a large range of genome sizes. This newly discovered diversity allows a better understanding of the evolutionary plasticity and conservation of animal mtDNA and provides insights into the molecular and evolutionary mechanisms shaping mitochondrial genomes. PMID:27557826

Systems Genetic Analysis of Osteoblast-Lineage Cells

PubMed Central

Calabrese, Gina; Bennett, Brian J.; Orozco, Luz; Kang, Hyun M.; Eskin, Eleazar; Dombret, Carlos; De Backer, Olivier; Lusis, Aldons J.; Farber, Charles R.

2012-01-01

The osteoblast-lineage consists of cells at various stages of maturation that are essential for skeletal development, growth, and maintenance. Over the past decade, many of the signaling cascades that regulate this lineage have been elucidated; however, little is known of the networks that coordinate, modulate, and transmit these signals. Here, we identify a gene network specific to the osteoblast-lineage through the reconstruction of a bone co-expression network using microarray profiles collected on 96 Hybrid Mouse Diversity Panel (HMDP) inbred strains. Of the 21 modules that comprised the bone network, module 9 (M9) contained genes that were highly correlated with prototypical osteoblast maker genes and were more highly expressed in osteoblasts relative to other bone cells. In addition, the M9 contained many of the key genes that define the osteoblast-lineage, which together suggested that it was specific to this lineage. To use the M9 to identify novel osteoblast genes and highlight its biological relevance, we knocked-down the expression of its two most connected “hub” genes, Maged1 and Pard6g. Their perturbation altered both osteoblast proliferation and differentiation. Furthermore, we demonstrated the mice deficient in Maged1 had decreased bone mineral density (BMD). It was also discovered that a local expression quantitative trait locus (eQTL) regulating the Wnt signaling antagonist Sfrp1 was a key driver of the M9. We also show that the M9 is associated with BMD in the HMDP and is enriched for genes implicated in the regulation of human BMD through genome-wide association studies. In conclusion, we have identified a physiologically relevant gene network and used it to discover novel genes and regulatory mechanisms involved in the function of osteoblast-lineage cells. Our results highlight the power of harnessing natural genetic variation to generate co-expression networks that can be used to gain insight into the function of specific cell-types. PMID

Aim-less translation: loss of Saccharomyces cerevisiae mitochondrial translation initiation factor mIF3/Aim23 leads to unbalanced protein synthesis.

PubMed

Kuzmenko, Anton; Derbikova, Ksenia; Salvatori, Roger; Tankov, Stoyan; Atkinson, Gemma C; Tenson, Tanel; Ott, Martin; Kamenski, Piotr; Hauryliuk, Vasili

2016-01-05

The mitochondrial genome almost exclusively encodes a handful of transmembrane constituents of the oxidative phosphorylation (OXPHOS) system. Coordinated expression of these genes ensures the correct stoichiometry of the system's components. Translation initiation in mitochondria is assisted by two general initiation factors mIF2 and mIF3, orthologues of which in bacteria are indispensible for protein synthesis and viability. mIF3 was thought to be absent in Saccharomyces cerevisiae until we recently identified mitochondrial protein Aim23 as the missing orthologue. Here we show that, surprisingly, loss of mIF3/Aim23 in S. cerevisiae does not indiscriminately abrogate mitochondrial translation but rather causes an imbalance in protein production: the rate of synthesis of the Atp9 subunit of F1F0 ATP synthase (complex V) is increased, while expression of Cox1, Cox2 and Cox3 subunits of cytochrome c oxidase (complex IV) is repressed. Our results provide one more example of deviation of mitochondrial translation from its bacterial origins.

Pancreas lineage allocation and specification are regulated by sphingosine-1-phosphate signalling.

PubMed

Serafimidis, Ioannis; Rodriguez-Aznar, Eva; Lesche, Mathias; Yoshioka, Kazuaki; Takuwa, Yoh; Dahl, Andreas; Pan, Duojia; Gavalas, Anthony

2017-03-01

During development, progenitor expansion, lineage allocation, and implementation of differentiation programs need to be tightly coordinated so that different cell types are generated in the correct numbers for appropriate tissue size and function. Pancreatic dysfunction results in some of the most debilitating and fatal diseases, including pancreatic cancer and diabetes. Several transcription factors regulating pancreas lineage specification have been identified, and Notch signalling has been implicated in lineage allocation, but it remains unclear how these processes are coordinated. Using a combination of genetic approaches, organotypic cultures of embryonic pancreata, and genomics, we found that sphingosine-1-phosphate (S1p), signalling through the G protein coupled receptor (GPCR) S1pr2, plays a key role in pancreas development linking lineage allocation and specification. S1pr2 signalling promotes progenitor survival as well as acinar and endocrine specification. S1pr2-mediated stabilisation of the yes-associated protein (YAP) is essential for endocrine specification, thus linking a regulator of progenitor growth with specification. YAP stabilisation and endocrine cell specification rely on Gαi subunits, revealing an unexpected specificity of selected GPCR intracellular signalling components. Finally, we found that S1pr2 signalling posttranscriptionally attenuates Notch signalling levels, thus regulating lineage allocation. Both S1pr2-mediated YAP stabilisation and Notch attenuation are necessary for the specification of the endocrine lineage. These findings identify S1p signalling as a novel key pathway coordinating cell survival, lineage allocation, and specification and linking these processes by regulating YAP levels and Notch signalling. Understanding lineage allocation and specification in the pancreas will shed light in the origins of pancreatic diseases and may suggest novel therapeutic approaches.

Pancreas lineage allocation and specification are regulated by sphingosine-1-phosphate signalling

PubMed Central

Serafimidis, Ioannis; Rodriguez-Aznar, Eva; Lesche, Mathias; Yoshioka, Kazuaki; Takuwa, Yoh; Dahl, Andreas; Pan, Duojia; Gavalas, Anthony

2017-01-01

During development, progenitor expansion, lineage allocation, and implementation of differentiation programs need to be tightly coordinated so that different cell types are generated in the correct numbers for appropriate tissue size and function. Pancreatic dysfunction results in some of the most debilitating and fatal diseases, including pancreatic cancer and diabetes. Several transcription factors regulating pancreas lineage specification have been identified, and Notch signalling has been implicated in lineage allocation, but it remains unclear how these processes are coordinated. Using a combination of genetic approaches, organotypic cultures of embryonic pancreata, and genomics, we found that sphingosine-1-phosphate (S1p), signalling through the G protein coupled receptor (GPCR) S1pr2, plays a key role in pancreas development linking lineage allocation and specification. S1pr2 signalling promotes progenitor survival as well as acinar and endocrine specification. S1pr2-mediated stabilisation of the yes-associated protein (YAP) is essential for endocrine specification, thus linking a regulator of progenitor growth with specification. YAP stabilisation and endocrine cell specification rely on Gαi subunits, revealing an unexpected specificity of selected GPCR intracellular signalling components. Finally, we found that S1pr2 signalling posttranscriptionally attenuates Notch signalling levels, thus regulating lineage allocation. Both S1pr2-mediated YAP stabilisation and Notch attenuation are necessary for the specification of the endocrine lineage. These findings identify S1p signalling as a novel key pathway coordinating cell survival, lineage allocation, and specification and linking these processes by regulating YAP levels and Notch signalling. Understanding lineage allocation and specification in the pancreas will shed light in the origins of pancreatic diseases and may suggest novel therapeutic approaches. PMID:28248965

Association between Mycobacterium tuberculosis lineage and site of disease in Florida, 2009-2015.

PubMed

Séraphin, Marie Nancy; Doggett, Richard; Johnston, Lori; Zabala, Jose; Gerace, Alexandra M; Lauzardo, Michael

2017-11-01

Mycobacterium tuberculosis is characterized into four global lineages with strong geographical restriction. To date one study in the United States has investigated M. tuberculosis lineage association with tuberculosis (TB) disease presentation (extra-pulmonary versus pulmonary). We update this analysis using recent (2009-2015) data from the State of Florida to measure lineage association with pulmonary TB, the infectious form of the disease. M. tuberculosis lineage was assigned based on the spacer oligonucleotide typing (spoligotyping) patterns. TB disease site was defined as exclusively pulmonary or extra-pulmonary. We used ORs to measure the association between M. tuberculosis lineages and pulmonary compared to extra-pulmonary TB. The final multivariable model was adjusted for patient socio-demographics, HIV and diabetes status. We analyzed 3061 cases, 83.4% were infected with a Euro-American lineage, 8.4% Indo-Oceanic and 8.2% East-Asian lineage. The majority of the cases (86.0%) were exclusively pulmonary. Compared to the Indo-Oceanic lineage, infection with a Euro-American (AOR=1.87, 95% CI: 1.21, 2.91) or an East-Asian (AOR=2.11, 95% CI: 1.27, 3.50) lineage favored pulmonary disease compared to extra-pulmonary. In a sub-analysis among pulmonary cases, strain lineage was not associated with sputum smear positive status, indicating that the observed association with pulmonary disease is independent of host contagiousness. As an obligate pathogen, M. tuberculosis' fitness is directly correlated to its transmission potential. In this analysis, we show that M. tuberculosis lineage is associated with pulmonary disease presentation. This association may explain the predominance in a region of certain lineages compared to others. Copyright © 2017 Elsevier B.V. All rights reserved.

Large-scale mitochondrial DNA analysis of native honey bee Apis mellifera populations reveals a new African subgroup private to the South West Indian Ocean islands.

PubMed

Techer, Maéva Angélique; Clémencet, Johanna; Simiand, Christophe; Preeaduth, Sookar; Azali, Hamza Abdou; Reynaud, Bernard; Hélène, Delatte

2017-06-02

The South West Indian Ocean (SWIO) archipelagos and Madagascar constitute a hotspot of biodiversity with a high rate of endemism. In this area, the endemic subspecies A. m. unicolor has been described in Madagascar. It belongs to the African lineage, one of the four described evolutionary lineages in honey bees. Despite a long beekeeping tradition and several recorded European introductions, few studies have been carried out on the diversity and proportion of honey bee subspecies. In order to identify and define which evolutionary lineages and potential sub-lineages are present in the SWIO, the COI-COII intergenic region and the ND2 gene of the mtDNA were sequenced in honey bee colonies from three archipelagos. An extensive sampling (n = 1184 colonies) was done in the Mascarene (La Réunion, Mauritius, Rodrigues), Seychelles (Mahé, Praslin, La Digue) and Comoros (Grande Comore, Mohéli, Anjouan, Mayotte) archipelagos. Islands genetic diversity was compared to newly sampled populations from Madagascar, continental African and European populations. African lineage haplotypes were found in all islands (except for Rodrigues). Madagascar, Comoros and Seychelles had 100% of A lineage, 95.5% in La Réunion and 56.1% in Mauritius. Among all African colonies detected in the SWIO, 98.1% (n = 633) of COI-COII haplotypes described the presence of the subspecies A. M. unicolor. Both genetic markers revealed i) a new private A I mitochondrial group shared by the SWIO archipelagos and Madagascar distant from continental populations; ii) the private African haplotypes for each island suggested diversity radiation in the archipelagos; iii) the detection of the Comoros archipelago as a possible contact area between insular and continental African populations. The exotic European C and M lineages were only detected in the Mascarene archipelago, but striking differences of proportion were observed among islands. Merely 4.6% of European colonies were found in La Réunion whereas

DLP1-Dependent Mitochondrial Fragmentation Mediates 1-methyl-4-phenylpyridinium Toxicity in Neurons: Implications for Parkinson's Disease

PubMed Central

Wang, Xinglong; Su, Bo; Liu, Wanhong; He, Xiaohua; Gao, Yuan; Castellani, Rudy J.; Perry, George; Smith, Mark A.; Zhu, Xiongwei

2011-01-01

SUMMARY Selective degeneration of nigrostriatal dopaminergic neurons in Parkinson disease (PD) can be modeled by the administration of the neurotoxin 1-methyl-4-phenylpyridinium (MPP+). Since abnormal mitochondrial dynamics are increasingly implicated in the pathogenesis of PD, in this study, we investigated the effect of MPP+ on mitochondrial dynamics and assessed temporal and causal relationship with other toxic effects induced by MPP+ in neuronal cells. In SH-SY5Y cells, MPP+ causes a rapid increase in mitochondrial fragmentation followed by a second wave of increase in mitochondrial fragmentation, along with increased DLP1 expression and mitochondrial translocation. Genetic inactivation of DLP1 completely blocks MPP+-induced mitochondrial fragmentation. Notably, this approach partially rescues MPP+-induced decline in ATP levels and ATP/ADP ratio and increased [Ca2+]i and almost completely prevents increased reactive oxygen species production, loss of mitochondrial membrane potential, enhanced autophagy and cell death, suggesting that mitochondria fragmentation is an upstream event that mediates MPP+-induced toxicity. On the other hand, thiol antioxidant NAC or glutamate receptor antagonist D-AP5 also partially alleviate MPP+-induced mitochondrial fragmentation, suggesting a vicious spiral of events contributes to MPP+-induced toxicity. We further validated our findings in primary rat midbrain dopaminergic neurons that 0.5 μM MPP+ induced mitochondrial fragmentation only in TH-positive dopaminergic neurons in a similar pattern to that in SH-SY5Y cells but had no effects on these mitochondrial parameters in TH-negative neurons. Overall, these findings suggest that DLP1-dependent mitochondrial fragmentation plays a crucial role in mediating MPP+-induced mitochondria abnormalities and cellular dysfunction and may represent a novel therapeutic target for PD. PMID:21615675

Origin of Pest Lineages of the Colorado Potato Beetle (Coleoptera: Chrysomelidae).

PubMed

Izzo, Victor M; Chen, Yolanda H; Schoville, Sean D; Wang, Cong; Hawthorne, David J

2018-04-02

Colorado potato beetle (Leptinotarsa decemlineata Say [Coleoptera: Chrysomelidae]) is a pest of potato throughout the Northern Hemisphere, but little is known about the beetle's origins as a pest. We sampled the beetle from uncultivated Solanum host plants in Mexico, and from pest and non-pest populations in the United States and used mitochondrial DNA and nuclear loci to examine three hypotheses on the origin of the pest lineages: 1) the pest beetles originated from Mexican populations, 2) they descended from hybridization between previously divergent populations, or 3) they descended from populations that are native to the Plains states in the United States. Mitochondrial haplotypes of non-pest populations from Mexico and Arizona differed substantially from beetles collected from the southern plains and potato fields in the United States, indicating that beetles from Mexico and Arizona did not contribute to founding the pest lineages. Similar results were observed for AFLP and microsatellite data . In contrast, non-pest populations from the states of Colorado, Kansas, Nebraska, New Mexico, and Texas were genetically similar to U.S. pest populations, indicating that they contributed to the founding of the pest lineages. Most of the pest populations do not show a significant reduction in genetic diversity compared to the plains populations in the United States. We conclude that genetically heterogeneous beetle populations expanded onto potato from native Solanum hosts. This mode of host range expansion may have contributed to the abundant genetic diversity of contemporary populations, perhaps contributing to the rapid evolution of climate tolerance, host range, and insecticide resistance.

Historical biogeography of Reticulitermes termites (Isoptera: Rhinotermitidae) inferred from analyses of mitochondrial and nuclear loci.

PubMed

Dedeine, Franck; Dupont, Simon; Guyot, Sylvain; Matsuura, Kenji; Wang, Changlu; Habibpour, Behzad; Bagnères, Anne-Geneviève; Mantovani, Barbara; Luchetti, Andrea

2016-01-01

Termites of the genus Reticulitermes are ecologically and economically important wood-feeding social insects that are widespread in the Holarctic region. Despite their importance, no study has yet attempted to reconstruct a global time-scaled phylogeny of Reticulitermes termites. In this study, we sequenced mitochondrial (2096bp) and nuclear (829bp) loci from 61 Reticulitermes specimens, collected across the genus' entire range, and one specimen of Coptotermes formosanus, which served as an outgroup. Bayesian and Maximum likelihood analyses conducted on the mitochondrial and nuclear sequences support the existence of four main lineages that span four global geographical regions: North America (NA lineage), western Europe (WE lineage), a region including eastern Europe and western Asia (EA+WA lineage), and eastern Asia (EA lineage). The mitochondrial data allowed us to clarify the phylogenetic relationships among these lineages. They were also used to infer a chronogram that was time scaled based on age estimates for termite fossils (including the oldest Reticulitermes fossils, which date back to the late Eocene-early Oligocene). Our results support the hypothesis that the extant Reticulitermes lineage first differentiated in North America. The first divergence event in the ancestral lineage of Reticulitermes occurred in the early Miocene and separated the Nearctic lineages (i.e., the NA lineages) from the Palearctic lineages (i.e., WE, EE+WA, and EA lineages). Our analyses revealed that the main lineages of Reticulitermes diversified because of vicariance and migration events, which were probably induced by major paleogeographic and paleoclimatic changes that occurred during the Cenozoic era. This is the first global and comprehensive phylogenetic study of Reticulitermes termites, and it provides a crucial foundation for studying the evolution of phenotypic and life-history traits in Reticulitermes. For instance, the phylogeny we obtained suggested that 'asexual

Reconstructing the colonization history of lost wolf lineages by the analysis of the mitochondrial genome.

PubMed

Matsumura, Shuichi; Inoshima, Yasuo; Ishiguro, Naotaka

2014-11-01

The grey wolves (Canis lupus) originally inhabited major parts of the Northern hemisphere, but many local populations became extinct. Two lineages of wolves in Japan, namely, Japanese or Honshu (C. l. hodophilax) and Ezo or Hokkaido (C. l. hattai) wolves, rapidly went extinct between 100 and 120years ago. Here we analyse the complete mitochondrial genome sequences from ancient specimens and reconstruct the colonization history of the two extinct subspecies. We show a unique status of Japanese wolves in wolf phylogeny, suggesting their long time separation from other grey wolf populations. Japanese wolves appeared to have colonized the Japanese archipelago in the Late Pleistocene (ca. 25,000-125,000years ago). By contrast, Ezo wolves, which are clearly separated from Japanese wolves in phylogeny, are likely to have arrived at Japan relatively recently (<14,000years ago). Interestingly, their colonization history to Japan tallies well with the dynamics of wolf populations in Europe and America during the last several millennia. Our analyses suggest that at least several thousands of wolves once inhabited in the Japanese archipelago. Our analyses also show that an enigmatic clade of domestic dogs is likely to have originated from rare admixture events between male dogs and female Japanese wolves. Copyright © 2014 Elsevier Inc. All rights reserved.

Drosophila mitochondrial topoisomerase III alpha affects the aging process via maintenance of mitochondrial function and genome integrity.

PubMed

Tsai, Han-Zen; Lin, Ren-Kuo; Hsieh, Tao-Shih

2016-04-12

Mitochondria play important roles in providing metabolic energy and key metabolites for synthesis of cellular building blocks. Mitochondria have additional functions in other cellular processes, including programmed cell death and aging. A previous study revealed Drosophila mitochondrial topoisomerase III alpha (Top3α) contributes to the maintenance of the mitochondrial genome and male germ-line stem cells. However, the involvement of mitochondrial Top3α in the mitochondrion-mediated aging process remains unclear. In this study, the M1L flies, in which Top3α protein lacks the mitochondrial import sequence and is thus present in cell nuclei but not in mitochondria, is used as a model system to examine the role of mitochondrial Top3α in the aging of fruit flies. Here, we reported that M1L flies exhibit mitochondrial defects which affect the aging process. First, we observed that M1L flies have a shorter life span, which was correlated with a significant reduction in the mitochondrial DNA copy number, the mitochondrial membrane potential, and ATP content compared with those of both wildtype and transgene-rescued flies of the same age. Second, we performed a mobility assay and electron microscopic analysis to demonstrate that the locomotion defect and mitophagy of M1L flies were enhanced with age, as compared with the controls. Finally, we showed that the correlation between the mtDNA deletion level and aging in M1L flies resembles what was reported in mammalian systems. The results reported here demonstrate that mitochondrial Top3α ablation results in mitochondrial genome instability and its dysfunction, thereby accelerating the aging process.

Microbiopsies versus Bergström needle for skeletal muscle sampling: impact on maximal mitochondrial respiration rate.

PubMed

Isner-Horobeti, M E; Charton, A; Daussin, F; Geny, B; Dufour, S P; Richard, R

2014-05-01

Microbiopsies are increasingly used as an alternative to the standard Bergström technique for skeletal muscle sampling. The potential impact of these two different procedures on mitochondrial respiration rate is unknown. The objective of this work was to compare microbiopsies versus Bergström procedure on mitochondrial respiration in skeletal muscle. 52 vastus lateralis muscle samples were obtained from 13 anesthetized pigs, either with a Bergström [6 gauges (G)] needle or with microbiopsy needles (12, 14, 18G). Maximal mitochondrial respiration (V GM-ADP) was assessed using an oxygraphic method on permeabilized fibers. The weight of the muscle samples and V GM-ADP decreased with the increasing gauge of the needles. A positive nonlinear relationship was observed between the weight of the muscle sample and the level of maximal mitochondrial respiration (r = 0.99, p < 0.05) and between needle size and maximal mitochondrial respiration (r = 0.99, p < 0.05). Microbiopsies give lower muscle sample weight and maximal rate of mitochondrial respiration compared to the standard Bergström needle.Therefore, the higher the gauge (i.e. the smaller the size) of the microbiopsy needle, the lower is the maximal rate of respiration. Microbiopsies of skeletal muscle underestimate the maximal mitochondrial respiration rate, and this finding needs to be highlighted for adequate interpretation and comparison with literature data.

Activation of mPTP-dependent mitochondrial apoptosis pathway by a novel pan HDAC inhibitor resminostat in hepatocellular carcinoma cells

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

Fu, Meili; Shi, Wenhong; Li, Zhengling

Over-expression and aberrant activation of histone deacetylases (HDACs) are often associated with poor prognosis of hepatocellular carcinoma (HCC). Here, we evaluated the potential anti-hepatocellular carcinoma (HCC) cell activity by resminostat, a novel pan HDAC inhibitor (HDACi). We demonstrated that resminostat induced potent cytotoxic and anti-proliferative activity against established HCC cell lines (HepG2, HepB3, SMMC-7721) and patient-derived primary HCC cells. Further, resminostat treatment in HCC cells activated mitochondrial permeability transition pore (mPTP)-dependent apoptosis pathway, which was evidenced by physical association of cyclophilin-D and adenine nucleotide translocator 1 (ANT-1), mitochondrial depolarization, cytochrome C release and caspase-9 activation. Intriguingly, the mPTP blockers (sanglifehrinmore » A and cyclosporine A), shRNA knockdown of cyclophilin-D or the caspase-9 inhibitor dramatically attenuated resminostat-induced HCC cell apoptosis and cytotoxicity. Reversely, HCC cells with exogenous cyclophilin-D over-expression were hyper-sensitive to resminostat. Intriguingly, a low concentration of resminostat remarkably potentiated sorafenib-induced mitochondrial apoptosis pathway activation, leading to a profound cytotoxicity in HCC cells. The results of this preclinical study indicate that resminostat (or plus sorafenib) could be further investigated as a valuable anti-HCC strategy. - Highlights: • Resminostat inhibits human HCC cell survival and proliferation. • Resminostat activates mPTP-dependent mitochondrial apoptosis pathway in HCC cells. • Resminostat potentiates sorafenib-induced mitochondrial apoptosis pathway activation. • mPTP or caspase-9 inhibition attenuates apoptosis by resminostat or plus sorafenib.« less

Mitochondrial myopathy, lactic acidosis, and sideroblastic anemia (MLASA) plus associated with a novel de novo mutation (m.8969G>A) in the mitochondrial encoded ATP6 gene.

PubMed

Burrage, Lindsay C; Tang, Sha; Wang, Jing; Donti, Taraka R; Walkiewicz, Magdalena; Luchak, J Michael; Chen, Li-Chieh; Schmitt, Eric S; Niu, Zhiyv; Erana, Rodrigo; Hunter, Jill V; Graham, Brett H; Wong, Lee-Jun; Scaglia, Fernando

2014-11-01

Mitochondrial myopathy, lactic acidosis and sideroblastic anemia (MLASA) is a rare mitochondrial disorder that has previously been associated with mutations in PUS1 and YARS2. In the present report, we describe a 6-year old male with an MLASA plus phenotype. This patient had features of MLASA in the setting of developmental delay, sensorineural hearing loss, epilepsy, agenesis of the corpus callosum, failure to thrive, and stroke-like episodes. Sequencing of the mitochondrial genome identified a novel de novo, heteroplasmic mutation in the mitochondrial DNA (mtDNA) encoded ATP6 gene (m.8969G>A, p.S148N). Whole exome sequencing did not identify mutations or variants in PUS1 or YARS2 or any known nuclear genes that could affect mitochondrial function and explain this phenotype. Studies of fibroblasts derived from the patient revealed a decrease in oligomycin-sensitive respiration, a finding which is consistent with a complex V defect. Thus, this mutation in MT-ATP6 may represent the first mtDNA point mutation associated with the MLASA phenotype. Copyright © 2014 Elsevier Inc. All rights reserved.

IGF2BP2/IMP2-Deficient mice resist obesity through enhanced translation of Ucp1 mRNA and Other mRNAs encoding mitochondrial proteins.

PubMed

Dai, Ning; Zhao, Liping; Wrighting, Diedra; Krämer, Dana; Majithia, Amit; Wang, Yanqun; Cracan, Valentin; Borges-Rivera, Diego; Mootha, Vamsi K; Nahrendorf, Matthias; Thorburn, David R; Minichiello, Liliana; Altshuler, David; Avruch, Joseph

2015-04-07

Although variants in the IGF2BP2/IMP2 gene confer risk for type 2 diabetes, IMP2, an RNA binding protein, is not known to regulate metabolism. Imp2(-/-) mice gain less lean mass after weaning and have increased lifespan. Imp2(-/-) mice are highly resistant to diet-induced obesity and fatty liver and display superior glucose tolerance and insulin sensitivity, increased energy expenditure, and better defense of core temperature on cold exposure. Imp2(-/-) brown fat and Imp2(-/-) brown adipocytes differentiated in vitro contain more UCP1 polypeptide than Imp2(+/+) despite similar levels of Ucp1 mRNA; the Imp2(-/-)adipocytes also exhibit greater uncoupled oxygen consumption. IMP2 binds the mRNAs encoding Ucp1 and other mitochondrial components, and most exhibit increased translational efficiency in the absence of IMP2. In vitro IMP2 inhibits translation of mRNAs bearing the Ucp1 untranslated segments. Thus IMP2 limits longevity and regulates nutrient and energy metabolism in the mouse by controlling the translation of its client mRNAs. Copyright © 2015 Elsevier Inc. All rights reserved.

1,3-Butadiene-Induced Mitochondrial Dysfunction is Correlated with Mitochondrial CYP2E1 Activity in Collaborative Cross Mice

PubMed Central

Hartman, Jessica H.; Miller, Grover P.; Caro, Andres A.; Byrum, Stephanie D.; Orr, Lisa M.; Mackintosh, Samuel G.; Tackett, Alan J.; MacMillan-Crow, Lee Ann; Hallberg, Lance M.; Ameredes, Bill T.; Boysen, Gunnar

2017-01-01

Cytochrome P450 2E1 (CYP2E1) metabolizes low molecular weight hydrophobic compounds, including 1,3-butadiene, which is converted by CYP2E1 to electrophilic epoxide metabolites that covalently modify cellular proteins and DNA. Previous CYP2E1 studies have mainly focused on the enzyme localized in the endoplasmic reticulum (erCYP2E1); however, active CYP2E1 also localizes in mitochondria (mtCYP2E1) and the distribution of CYP2E1 between organelles can influence an individual's response to exposure. Relatively few studies have focused on the contribution of mtCYP2E1 to activation of chemical toxicants. We hypothesized that CYP2E1 bioactivation of butadiene within mitochondria adversely affects mitochondrial respiratory complexes I-IV. A population of Collaborative Cross mice were exposed to air (control) or 200 ppm butadiene. Subcellular fractions (mitochondria, DNA, and microsomes) were collected from frozen livers and CYP2E1 activity was measured in microsomes and mitochondria. Individual activities of mitochondrial respiratory complexes I-IV were measured using in vitro assays with purified mitochondrial fractions. In air- and butadiene-exposed mouse samples, mtDNA copy numbers were assessed by RT-PCR, and mtDNA integrity was assessed through a PCR-based assay. No significant change in mtDNA copy number or integrity were observed; however, there was a decrease in overall activity of mitochondrial respiratory complexes I, II, and IV after butadiene exposure. Additionally, higher mtCYP2E1 (but not erCYP2E1) activity was correlated with decreased mitochondrial respiratory complex activity (in complexes I-IV) in the butadiene-exposed (not control) animals. Together, these results represent the first in vivo link between mitochondrial CYP2E1 activity and mitochondrial toxicity. PMID:28082109

Drp1-Dependent Mitochondrial Autophagy Plays a Protective Role Against Pressure Overload-Induced Mitochondrial Dysfunction and Heart Failure.

PubMed

Shirakabe, Akihiro; Zhai, Peiyong; Ikeda, Yoshiyuki; Saito, Toshiro; Maejima, Yasuhiro; Hsu, Chiao-Po; Nomura, Masatoshi; Egashira, Kensuke; Levine, Beth; Sadoshima, Junichi

2016-03-29

Mitochondrial autophagy is an important mediator of mitochondrial quality control in cardiomyocytes. The occurrence of mitochondrial autophagy and its significance during cardiac hypertrophy are not well understood. Mice were subjected to transverse aortic constriction (TAC) and observed at multiple time points up to 30 days. Cardiac hypertrophy developed after 5 days, the ejection fraction was reduced after 14 days, and heart failure was observed 30 days after TAC. General autophagy was upregulated between 1 and 12 hours after TAC but was downregulated below physiological levels 5 days after TAC. Mitochondrial autophagy, evaluated by electron microscopy, mitochondrial content, and Keima with mitochondrial localization signal, was transiently activated at ≈3 to 7 days post-TAC, coinciding with mitochondrial translocation of Drp1. However, it was downregulated thereafter, followed by mitochondrial dysfunction. Haploinsufficiency of Drp1 abolished mitochondrial autophagy and exacerbated the development of both mitochondrial dysfunction and heart failure after TAC. Injection of Tat-Beclin 1, a potent inducer of autophagy, but not control peptide, on day 7 after TAC, partially rescued mitochondrial autophagy and attenuated mitochondrial dysfunction and heart failure induced by overload. Haploinsufficiency of either drp1 or beclin 1 prevented the rescue by Tat-Beclin 1, suggesting that its effect is mediated in part through autophagy, including mitochondrial autophagy. Mitochondrial autophagy is transiently activated and then downregulated in the mouse heart in response to pressure overload. Downregulation of mitochondrial autophagy plays an important role in mediating the development of mitochondrial dysfunction and heart failure, whereas restoration of mitochondrial autophagy attenuates dysfunction in the heart during pressure overload. © 2016 American Heart Association, Inc.

Mitochondrial dysfunction in autism.

PubMed

Giulivi, Cecilia; Zhang, Yi-Fan; Omanska-Klusek, Alicja; Ross-Inta, Catherine; Wong, Sarah; Hertz-Picciotto, Irva; Tassone, Flora; Pessah, Isaac N

2010-12-01

Impaired mitochondrial function may influence processes highly dependent on energy, such as neurodevelopment, and contribute to autism. No studies have evaluated mitochondrial dysfunction and mitochondrial DNA (mtDNA) abnormalities in a well-defined population of children with autism. To evaluate mitochondrial defects in children with autism. Observational study using data collected from patients aged 2 to 5 years who were a subset of children participating in the Childhood Autism Risk From Genes and Environment study in California, which is a population-based, case-control investigation with confirmed autism cases and age-matched, genetically unrelated, typically developing controls, that was launched in 2003 and is still ongoing. Mitochondrial dysfunction and mtDNA abnormalities were evaluated in lymphocytes from 10 children with autism and 10 controls. Oxidative phosphorylation capacity, mtDNA copy number and deletions, mitochondrial rate of hydrogen peroxide production, and plasma lactate and pyruvate. The reduced nicotinamide adenine dinucleotide (NADH) oxidase activity (normalized to citrate synthase activity) in lymphocytic mitochondria from children with autism was significantly lower compared with controls (mean, 4.4 [95% confidence interval {CI}, 2.8-6.0] vs 12 [95% CI, 8-16], respectively; P = .001). The majority of children with autism (6 of 10) had complex I activity below control range values. Higher plasma pyruvate levels were found in children with autism compared with controls (0.23 mM [95% CI, 0.15-0.31 mM] vs 0.08 mM [95% CI, 0.04-0.12 mM], respectively; P = .02). Eight of 10 cases had higher pyruvate levels but only 2 cases had higher lactate levels compared with controls. These results were consistent with the lower pyruvate dehydrogenase activity observed in children with autism compared with controls (1.0 [95% CI, 0.6-1.4] nmol × [min × mg protein](-1) vs 2.3 [95% CI, 1.7-2.9] nmol × [min × mg protein](-1), respectively; P = .01

Roles of mitochondrial fragmentation and reactive oxygen species in mitochondrial dysfunction and myocardial insulin resistance

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

Watanabe, Tomoyuki; Saotome, Masao, E-mail: msaotome@hama-med.ac.jp; Nobuhara, Mamoru

Purpose: Evidence suggests an association between aberrant mitochondrial dynamics and cardiac diseases. Because myocardial metabolic deficiency caused by insulin resistance plays a crucial role in heart disease, we investigated the role of dynamin-related protein-1 (DRP1; a mitochondrial fission protein) in the pathogenesis of myocardial insulin resistance. Methods and Results: DRP1-expressing H9c2 myocytes, which had fragmented mitochondria with mitochondrial membrane potential (ΔΨ{sub m}) depolarization, exhibited attenuated insulin signaling and 2-deoxy-D-glucose (2-DG) uptake, indicating insulin resistance. Treatment of the DRP1-expressing myocytes with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride (TMPyP) significantly improved insulin resistance and mitochondrial dysfunction. When myocytes were exposed to hydrogen peroxide (H{sub 2}O{sub 2}),more » they increased DRP1 expression and mitochondrial fragmentation, resulting in ΔΨ{sub m} depolarization and insulin resistance. When DRP1 was suppressed by siRNA, H{sub 2}O{sub 2}-induced mitochondrial dysfunction and insulin resistance were restored. Our results suggest that a mutual enhancement between DRP1 and reactive oxygen species could induce mitochondrial dysfunction and myocardial insulin resistance. In palmitate-induced insulin-resistant myocytes, neither DRP1-suppression nor TMPyP restored the ΔΨ{sub m} depolarization and impaired 2-DG uptake, however they improved insulin signaling. Conclusions: A mutual enhancement between DRP1 and ROS could promote mitochondrial dysfunction and inhibition of insulin signal transduction. However, other mechanisms, including lipid metabolite-induced mitochondrial dysfunction, may be involved in palmitate-induced insulin resistance. - Highlights: • DRP1 promotes mitochondrial fragmentation and insulin-resistance. • A mutual enhancement between DRP1 and ROS ipromotes insulin-resistance. • Palmitate increases DRP1 expression and induces insulin

Brg1 modulates enhancer activation in mesoderm lineage commitment

DOE PAGES

Alexander, Jeffrey M.; Hota, Swetansu K.; He, Daniel; ...

2015-03-26

The interplay between different levels of gene regulation in modulating developmental transcriptional programs, such as histone modifications and chromatin remodeling, is not well understood. Here, we show that the chromatin remodeling factor Brg1 is required for enhancer activation in mesoderm induction. In an embryonic stem cell-based directed differentiation assay, the absence of Brg1 results in a failure of cardiomyocyte differentiation and broad deregulation of lineage-specific gene expression during mesoderm induction. We find that Brg1 co-localizes with H3K27ac at distal enhancers and is required for robust H3K27 acetylation at distal enhancers that are activated during mesoderm induction. Brg1 is also requiredmore » to maintain Polycomb-mediated repression of non-mesodermal developmental regulators, suggesting cooperativity between Brg1 and Polycomb complexes. Thus, Brg1 is essential for modulating active and repressive chromatin states during mesoderm lineage commitment, in particular the activation of developmentally important enhancers. In conclusion, these findings demonstrate interplay between chromatin remodeling complexes and histone modifications that, together, ensure robust and broad gene regulation during crucial lineage commitment decisions.« less

Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

PubMed

Ravago-Gotanco, Rachel; de la Cruz, Talna Lorena; Pante, Ma Josefa; Borsa, Philippe

2018-01-01

The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clade A and Clade B) or S. canaliculatus (Clade C). We report the existence of two cryptic species within S. fuscescens in the northeast region of the South China Sea and northern Philippine Sea, supported by genetic and morphological differences. Individual-based assignment methods recovered concordant groupings of individuals into two nuclear genotype clusters (Cluster 1, Cluster 2) with (1) limited gene flow, if any, between them (FST = 0.241; P < 0.001); (2) low frequency of later-generation hybrids; (3) significant association with mitochondrial Clade A and Clade B, respectively; and (4) subtle yet significant body shape differences as inferred from geometric morphometric analysis. The divergence between mitochondrial Clade C and the two other clades was not matched by genetic differences at microsatellite marker loci. The occurrence of discordant mitonuclear combinations (20.5% of the total number of individuals) is thought to result from mitochondrial introgression, consistent with a scenario of demographic, and presumably spatial, post-Pleistocene expansion of populations from northern regions into a secondary contact zone in the South China Sea. Mitonuclear discordance due to introgression obscures phylogenetic relationships for recently-diverged lineages, and cautions against the use of mitochondrial markers alone for species identification within the mottled rabbitfish species complex in the South China Sea region.

Host-induced genome alterations in Phytophthora ramorum, I. NA1 lineage on coast live oak in California, II. EU1 lineage on Chamaecyparis lawsoniana in UK

Treesearch

Takao Kasuga; Mai Bui; Elizabeth Bernhardt; Tedmund Swiecki; Kamyar Aram; Lien Bertier; Jennifer Yuzon; Liliana M. Cano; Joan Webber; Clive Brasier; Caroline Press; Niklaus Grünwald; David Rizzo; Matteo Garbelotto

2017-01-01

Rapid phenotypic diversification in clonal invasive populations is often observed, although the underlying genetic mechanisms remain elusive. Lineages of the sudden oak death pathogen Phytophthora ramorum are exclusively clonal, yet isolates of the NA1 lineage from oak (Quercus spp.) frequently exhibit...

4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to inhibit hepatocellular carcinoma cells

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

Fu, Meili, E-mail: fumeilidrlinyi@tom.com; Wan, Fuqiang; Li, Zhengling

The aim of the present study is to investigate the potential anti-hepatocellular carcinoma (HCC) cell activity by 4SC-202, a novel class I HDAC inhibitor (HDACi). The associated signaling mechanisms were also analyzed. We showed that 4SC-202 treatment induced potent cytotoxic and proliferation–inhibitory activities against established HCC cell lines (HepG2, HepB3, SMMC-7721) and patient-derived primary HCC cells. Further, adding 4SC-202 in HCC cells activated mitochondrial apoptosis pathway, which was evidenced by mitochondrial permeability transition pore (mPTP) opening, cytochrome C cytosol release and caspase-3/-9 activation. Inhibition of this apoptosis pathway, by caspase-3/-9 inhibitors, mPTP blockers, or by shRNA-mediated knockdown of cyclophilin-D (Cyp-D,more » a key component of mPTP), significantly attenuated 4SC-202-induced HCC cell death and apoptosis. Reversely, over-expression of Cyp-D enhanced 4SC-202's sensitivity in HCC cells. Further studies showed that 4SC-202 induced apoptosis signal-regulating kinase 1 (ASK1) activation, causing it translocation to mitochondria and physical association with Cyp-D. This mitochondrial ASK1-Cyp-D complexation appeared required for mediating 4SC-202-induced apoptosis activation. ASK1 stable knockdown by targeted-shRNAs largely inhibited 4SC-202-induced mPTP opening, cytochrome C release, and following HCC cell apoptotic death. Together, we suggest that 4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to potently inhibit human HCC cells. - Highlights: • 4SC-202 exerts potent anti-proliferative and cytotoxic activity against established/primary HCC cells. • SC-202-induced anti-HCC cell activity relies on caspase-dependent apoptosis activation. • 4SC-202 activates Cyp-D-dependent mitochondrial apoptosis pathway in HCC cells. • 4SC-202 activates ASK1 in HCC cells, causing it translocation to mitochondria. • Mitochondrial ASK1-Cyp-D complexation mediates 4SC-202's activity in HCC cells.« less

Corresponding Mitochondrial DNA and Niche Divergence for Crested Newt Candidate Species

PubMed Central

Wielstra, Ben; Beukema, Wouter; Arntzen, Jan W.; Skidmore, Andrew K.; Toxopeus, Albertus G.; Raes, Niels

2012-01-01

Genetic divergence of mitochondrial DNA does not necessarily correspond to reproductive isolation. However, if mitochondrial DNA lineages occupy separate segments of environmental space, this supports the notion of their evolutionary independence. We explore niche differentiation among three candidate species of crested newt (characterized by distinct mitochondrial DNA lineages) and interpret the results in the light of differences observed for recognized crested newt species. We quantify niche differences among all crested newt (candidate) species and test hypotheses regarding niche evolution, employing two ordination techniques (PCA-env and ENFA). Niche equivalency is rejected: all (candidate) species are found to occupy significantly different segments of environmental space. Furthermore, niche overlap values for the three candidate species are not significantly higher than those for the recognized species. As the three candidate crested newt species are, not only in terms of mitochondrial DNA genetic divergence, but also ecologically speaking, as diverged as the recognized crested newt species, our findings are in line with the hypothesis that they represent cryptic species. We address potential pitfalls of our methodology. PMID:23029564

The mitochondrial outer membrane protein hFis1 regulates mitochondrial morphology and fission through self-interaction

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

Serasinghe, Madhavika N.; Mitochondrial Research and Innovation Group, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Yoon, Yisang

2008-11-15

Mitochondrial fission in mammals is mediated by at least two proteins, DLP1/Drp1 and hFis1. DLP1 mediates the scission of mitochondrial membranes through GTP hydrolysis, and hFis1 is a putative DLP1 receptor anchored at the mitochondrial outer membrane by a C-terminal single transmembrane domain. The cytosolic domain of hFis1 contains six {alpha}-helices ({alpha}1-{alpha}6) out of which {alpha}2-{alpha}5 form two tetratricopeptide repeat (TPR) folds. In this study, by using chimeric constructs, we demonstrated that the cytosolic domain contains the necessary information for hFis1 function during mitochondrial fission. By using transient expression of different mutant forms of the hFis1 protein, we found thatmore » hFis1 self-interaction plays an important role in mitochondrial fission. Our results show that deletion of the {alpha}1 helix greatly increased the formation of dimeric and oligomeric forms of hFis1, indicating that {alpha}1 helix functions as a negative regulator of the hFis1 self-interaction. Further mutational approaches revealed that a tyrosine residue in the {alpha}5 helix and the linker between {alpha}3 and {alpha}4 helices participate in hFis1 oligomerization. Mutations causing oligomerization defect greatly reduced the ability to induce not only mitochondrial fragmentation by full-length hFis1 but also the formation of swollen ball-shaped mitochondria caused by {alpha}1-deleted hFis1. Our data suggest that oligomerization of hFis1 in the mitochondrial outer membrane plays a role in mitochondrial fission, potentially through participating in fission factor recruitment.« less

Effect of insulin on human skeletal muscle mitochondrial ATP production, protein synthesis, and mRNA transcripts

NASA Astrophysics Data System (ADS)

Stump, Craig S.; Short, Kevin R.; Bigelow, Maureen L.; Schimke, Jill M.; Sreekumaran Nair, K.

2003-06-01

Mitochondria are the primary site of skeletal muscle fuel metabolism and ATP production. Although insulin is a major regulator of fuel metabolism, its effect on mitochondrial ATP production is not known. Here we report increases in vastus lateralis muscle mitochondrial ATP production capacity (32-42%) in healthy humans (P < 0.01) i.v. infused with insulin (1.5 milliunits/kg of fat-free mass per min) while clamping glucose, amino acids, glucagon, and growth hormone. Increased ATP production occurred in association with increased mRNA levels from both mitochondrial (NADH dehydrogenase subunit IV) and nuclear [cytochrome c oxidase (COX) subunit IV] genes (164-180%) encoding mitochondrial proteins (P < 0.05). In addition, muscle mitochondrial protein synthesis, and COX and citrate synthase enzyme activities were increased by insulin (P < 0.05). Further studies demonstrated no effect of low to high insulin levels on muscle mitochondrial ATP production for people with type 2 diabetes mellitus, whereas matched nondiabetic controls increased 16-26% (P < 0.02) when four different substrate combinations were used. In conclusion, insulin stimulates mitochondrial oxidative phosphorylation in skeletal muscle along with synthesis of gene transcripts and mitochondrial protein in human subjects. Skeletal muscle of type 2 diabetic patients has a reduced capacity to increase ATP production with high insulin levels. cytochrome c oxidase | NADH dehydrogenase subunit IV | amino acids | citrate synthase

Dynamin-Related Protein 1 and Mitochondrial Fragmentation in Neurodegenerative Diseases

PubMed Central

Reddy, P. Hemachandra; Reddy, Tejaswini P.; Manczak, Maria; Calkins, Marcus J.; Shirendeb, Ulziibat; Mao, Peizhong

2010-01-01

The purpose of this article is to review the recent developments of abnormal mitochondrial dynamics, mitochondrial fragmentation, and neuronal damage in neurodegenerative diseases, including Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis. The GTPase family of proteins, including fission proteins, dynamin related protein 1 (Drp1), mitochondrial fission 1 (Fis1), and fusion proteins (Mfn1, Mfn2 and Opa1) are essential to maintain mitochondrial fission and fusion balance, and to provide necessary adenosine triphosphate to neurons. Among these, Drp1 is involved in several important aspects of mitochondria, including shape, size, distribution, remodeling, and maintenance of X in mammalian cells. In addition, recent advancements in molecular, cellular, electron microscopy, and confocal imaging studies revealed that Drp1 is associated with several cellular functions, including mitochondrial and peroxisomal fragmentation, phosphorylation, SUMOylation, ubiquitination, and cell death. In the last two decades, tremendous progress has been made in researching mitochondrial dynamics, in yeast, worms, and mammalian cells; and this research has provided evidence linking Drp1 to neurodegenerative diseases. Researchers in the neurodegenerative disease field are beginning to recognize the possible involvement of Drp1 in causing mitochondrial fragmentation and abnormal mitochondrial dynamics in neurodegenerative diseases. This article summarizes research findings relating Drp1 to mitochondrial fission and fusion, in yeast, worms, and mammals. Based on findings from the Reddy laboratory and others’, we propose that mutant proteins of neurodegenerative diseases, including AD, PD, HD, and ALS, interact with Drp1, activate mitochondrial fission machinery, fragment mitochondria excessively, and impair mitochondrial transport and mitochondrial dynamics, ultimately causing mitochondrial dysfunction and neuronal damage. PMID:21145355

Mutational screening in patients with profound sensorineural hearing loss and neurodevelopmental delay: Description of a novel m.3861A > C mitochondrial mutation in the MT-ND1 gene.

PubMed

Ammar, Marwa; Tabebi, Mouna; Sfaihi, Lamia; Alila-Fersi, Olfa; Maalej, Marwa; Felhi, Rahma; Chabchoub, Imen; Keskes, Leila; Hachicha, Mongia; Fakhfakh, Faiza; Mkaouar-Rebai, Emna

2016-06-10

Mitochondrial diseases caused by mitochondrial dysfunction are a clinically and genetically, heterogeneous group of disorders involving multiple organs, particularly tissues with high-energy demand. Hearing loss is a recognized symptom of a number of mitochondrial diseases and can result from neuronal or cochlear dysfunction. The tissue affected in this pathology is most probably the cochlear hair cells, which are essential for hearing function since they are responsible for maintaining the ionic gradients necessary for sound signal transduction. Several mitochondrial DNA mutations have been associated with hearing loss and since mitochondria are crucial for the cellular energy supply in many tissues, most of these mtDNA mutations affect several tissues and will cause syndromic hearing loss. In the present study, we described 2 patients with sensorineural hearing loss and neurodevelopmental delay in whom we tested mitochondrial genes described to be associated with syndromic hearing loss. One of these patients showed a novel heteroplasmic mitochondrial mutation m.3861A > C (W185C) which lead to a loss of stability of the ND1 protein since it created a new hydrogen bund between the unique created cystein C185 and the A182 residue. In the second patient, we detected two novel heteroplasmic variations m.12350C > A (T5N) and m.14351T > C (E108G) respectively in the MT-ND5 and the MT-ND6 genes. The TopPred II prediction for the E108G variation revealed a decrease of the hydrophobicity in the mutated MT-ND6. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial Dysfunction and Its Relationship with mTOR Signaling and Oxidative Damage in Autism Spectrum Disorders.

PubMed

Yui, Kunio; Sato, Atsushi; Imataka, George

2015-01-01

Mitochondria are organelles that play a central role in processes related to cellular viability, such as energy production, cell growth, cell death via apoptosis, and metabolism of reactive oxygen species (ROS). We can observe behavioral abnormalities relevant to autism spectrum disorders (ASDs) and their recovery mediated by the mTOR inhibitor rapamycin in mouse models. In Tsc2(+/-) mice, the transcription of multiple genes involved in mTOR signaling is enhanced, suggesting a crucial role of dysregulated mTOR signaling in the ASD model. This review proposes that the mTOR inhibitor may be useful for the pharmacological treatment of ASD. This review offers novel insights into mitochondrial dysfunction and the related impaired glutathione synthesis and lower detoxification capacity. Firstly, children with ASD and concomitant mitochondrial dysfunction have been reported to manifest clinical symptoms similar to those of mitochondrial disorders, and it therefore shows that the clinical manifestations of ASD with a concomitant diagnosis of mitochondrial dysfunction are likely due to these mitochondrial disorders. Secondly, the adenosine triphosphate (ATP) production/oxygen consumption pathway may be a potential candidate for preventing mitochondrial dysfunction due to oxidative stress, and disruption of ATP synthesis alone may be related to impaired glutathione synthesis. Finally, a decrease in total antioxidant capacity may account for ASD children who show core social and behavioral impairments without neurological and somatic symptoms.

Overexpression of PGC-1α increases peroxisomal activity and mitochondrial fatty acid oxidation in human primary myotubes.

PubMed

Huang, Tai-Yu; Zheng, Donghai; Houmard, Joseph A; Brault, Jeffrey J; Hickner, Robert C; Cortright, Ronald N

2017-04-01

Peroxisomes are indispensable organelles for lipid metabolism in humans, and their biogenesis has been assumed to be under regulation by peroxisome proliferator-activated receptors (PPARs). However, recent studies in hepatocytes suggest that the mitochondrial proliferator PGC-1α (peroxisome proliferator-activated receptor gamma coactivator-1α) also acts as an upstream transcriptional regulator for enhancing peroxisomal abundance and associated activity. It is unknown whether the regulatory mechanism(s) for enhancing peroxisomal function is through the same node as mitochondrial biogenesis in human skeletal muscle (HSkM) and whether fatty acid oxidation (FAO) is affected. Primary myotubes from vastus lateralis biopsies from lean donors (BMI = 24.0 ± 0.6 kg/m 2 ; n = 6) were exposed to adenovirus encoding human PGC-1α or GFP control. Peroxisomal biogenesis proteins (peroxins) and genes ( PEXs ) responsible for proliferation and functions were assessed by Western blotting and real-time qRT-PCR, respectively. [1- 14 C]palmitic acid and [1- 14 C]lignoceric acid (exclusive peroxisomal-specific substrate) were used to assess mitochondrial oxidation of peroxisomal-derived metabolites. After overexpression of PGC-1α, 1 ) peroxisomal membrane protein 70 kDa (PMP70), PEX19, and mitochondrial citrate synthetase protein content were significantly elevated ( P < 0.05), 2 ) PGC-1α , PMP70 , key PEXs , and peroxisomal β-oxidation mRNA expression levels were significantly upregulated ( P < 0.05), and 3 ) a concomitant increase in lignoceric acid oxidation by both peroxisomal and mitochondrial activity was observed ( P < 0.05). These novel findings demonstrate that, in addition to the proliferative effect on mitochondria, PGC-1α can induce peroxisomal activity and accompanying elevations in long-chain and very-long-chain fatty acid oxidation by a peroxisomal-mitochondrial functional cooperation, as observed in HSkM cells. Copyright © 2017 the American Physiological Society.

Cyclophilin D Promotes Brain Mitochondrial F1FO ATP Synthase Dysfunction in Aging Mice

PubMed Central

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

Brain aging is the known strongest risk factor for Alzheimer’s disease (AD). In recent years, mitochondrial deficits have been proposed to be a common mechanism linking brain aging to AD. Therefore, to elucidate the causative mechanisms of mitochondrial dysfunction in aging brains is of paramount importance for our understanding of the pathogenesis of AD, in particular its sporadic form. Cyclophilin D (CypD) is a specific mitochondrial protein. Recent studies have shown that F1FO ATP synthase oligomycin sensitivity conferring protein (OSCP) is a binding partner of CypD. The interaction of CypD with OSCP modulates F1FO ATP synthase function and mediates mitochondrial permeability transition pore (mPTP) opening. Here, we have found that increased CypD expression, enhanced CypD/OSCP interaction, and selective loss of OSCP are prominent brain mitochondrial changes in aging mice. Along with these changes, brain mitochondria from the aging mice demonstrated decreased F1FO ATP synthase activity and defective F1FO complex coupling. In contrast, CypD deficient mice exhibited substantially mitigated brain mitochondrial F1FO ATP synthase dysfunction with relatively preserved mitochondrial function during aging. Interestingly, the aging-related OSCP loss was also dramatically attenuated by CypD depletion. Therefore, the simplest interpretation of this study is that CypD promotes F1FO ATP synthase dysfunction and the resultant mitochondrial deficits in aging brains. In addition, in view of CypD and F1FO ATP synthase alterations seen in AD brains, the results further suggest that CypD-mediated F1FO ATP synthase deregulation is a shared mechanism linking mitochondrial deficits in brain aging and AD. PMID:27834780

Cyclophilin D Promotes Brain Mitochondrial F1FO ATP Synthase Dysfunction in Aging Mice.

PubMed

Gauba, Esha; Guo, Lan; Du, Heng

2017-01-01

Brain aging is the known strongest risk factor for Alzheimer's disease (AD). In recent years, mitochondrial deficits have been proposed to be a common mechanism linking brain aging to AD. Therefore, to elucidate the causative mechanisms of mitochondrial dysfunction in aging brains is of paramount importance for our understanding of the pathogenesis of AD, in particular its sporadic form. Cyclophilin D (CypD) is a specific mitochondrial protein. Recent studies have shown that F1FO ATP synthase oligomycin sensitivity conferring protein (OSCP) is a binding partner of CypD. The interaction of CypD with OSCP modulates F1FO ATP synthase function and mediates mitochondrial permeability transition pore (mPTP) opening. Here, we have found that increased CypD expression, enhanced CypD/OSCP interaction, and selective loss of OSCP are prominent brain mitochondrial changes in aging mice. Along with these changes, brain mitochondria from the aging mice demonstrated decreased F1FO ATP synthase activity and defective F1FO complex coupling. In contrast, CypD deficient mice exhibited substantially mitigated brain mitochondrial F1FO ATP synthase dysfunction with relatively preserved mitochondrial function during aging. Interestingly, the aging-related OSCP loss was also dramatically attenuated by CypD depletion. Therefore, the simplest interpretation of this study is that CypD promotes F1FO ATP synthase dysfunction and the resultant mitochondrial deficits in aging brains. In addition, in view of CypD and F1FO ATP synthase alterations seen in AD brains, the results further suggest that CypD-mediated F1FO ATP synthase deregulation is a shared mechanism linking mitochondrial deficits in brain aging and AD.

The peopling of Europe and the cautionary tale of Y chromosome lineage R-M269

PubMed Central

Busby, George B. J.; Brisighelli, Francesca; Sánchez-Diz, Paula; Ramos-Luis, Eva; Martinez-Cadenas, Conrado; Thomas, Mark G.; Bradley, Daniel G.; Gusmão, Leonor; Winney, Bruce; Bodmer, Walter; Vennemann, Marielle; Coia, Valentina; Scarnicci, Francesca; Tofanelli, Sergio; Vona, Giuseppe; Ploski, Rafal; Vecchiotti, Carla; Zemunik, Tatijana; Rudan, Igor; Karachanak, Sena; Toncheva, Draga; Anagnostou, Paolo; Ferri, Gianmarco; Rapone, Cesare; Hervig, Tor; Moen, Torolf; Wilson, James F.; Capelli, Cristian

2012-01-01

Recently, the debate on the origins of the major European Y chromosome haplogroup R1b1b2-M269 has reignited, and opinion has moved away from Palaeolithic origins to the notion of a younger Neolithic spread of these chromosomes from the Near East. Here, we address this debate by investigating frequency patterns and diversity in the largest collection of R1b1b2-M269 chromosomes yet assembled. Our analysis reveals no geographical trends in diversity, in contradiction to expectation under the Neolithic hypothesis, and suggests an alternative explanation for the apparent cline in diversity recently described. We further investigate the young, STR-based time to the most recent common ancestor estimates proposed so far for R-M269-related lineages and find evidence for an appreciable effect of microsatellite choice on age estimates. As a consequence, the existing data and tools are insufficient to make credible estimates for the age of this haplogroup, and conclusions about the timing of its origin and dispersal should be viewed with a large degree of caution. PMID:21865258

Cyclin D1 Determines Mitochondrial Function In Vivo†

PubMed Central

Sakamaki, Toshiyuki; Casimiro, Mathew C.; Ju, Xiaoming; Quong, Andrew A.; Katiyar, Sanjay; Liu, Manran; Jiao, Xuanmao; Li, Anping; Zhang, Xueping; Lu, Yinan; Wang, Chenguang; Byers, Stephen; Nicholson, Robert; Link, Todd; Shemluck, Melvin; Yang, Jianguo; Fricke, Stanley T.; Novikoff, Phyllis M.; Papanikolaou, Alexandros; Arnold, Andrew; Albanese, Christopher; Pestell, Richard

2006-01-01

The cyclin D1 gene encodes a regulatory subunit of the holoenzyme that phosphorylates and inactivates the pRb tumor suppressor to promote nuclear DNA synthesis. cyclin D1 is overexpressed in human breast cancers and is sufficient for the development of murine mammary tumors. Herein, cyclin D1 is shown to perform a novel function, inhibiting mitochondrial function and size. Mitochondrial activity was enhanced by genetic deletion or antisense or small interfering RNA to cyclin D1. Global gene expression profiling and functional analysis of mammary epithelial cell-targeted cyclin D1 antisense transgenics demonstrated that cyclin D1 inhibits mitochondrial activity and aerobic glycolysis in vivo. Reciprocal regulation of these genes was observed in cyclin D1-induced mammary tumors. Cyclin D1 thus integrates nuclear DNA synthesis and mitochondrial function. PMID:16809779

Mitochondrial DNA transmission and confounding mitochondrial influences in cloned cattle and pigs.

PubMed

Takeda, Kumiko

2013-04-01

Although somatic cell nuclear transfer (SCNT) is a powerful tool for production of cloned animals, SCNT embryos generally have low developmental competency and many abnormalities. The interaction between the donor nucleus and the enucleated ooplasm plays an important role in early embryonic development, but the underlying mechanisms that negatively impact developmental competency remain unclear. Mitochondria have a broad range of critical functions in cellular energy supply, cell signaling, and programmed cell death; thus, affect embryonic and fetal development. This review focuses on mitochondrial considerations influencing SCNT techniques in farm animals. Donor somatic cell mitochondrial DNA (mtDNA) can be transmitted through what has been considered a "bottleneck" in mitochondrial genetics via the SCNT maternal lineage. This indicates that donor somatic cell mitochondria have a role in the reconstructed cytoplasm. However, foreign somatic cell mitochondria may affect the early development of SCNT embryos. Nuclear-mitochondrial interactions in interspecies/intergeneric SCNT (iSCNT) result in severe problems. A major biological selective pressure exists against survival of exogenous mtDNA in iSCNT. Yet, mtDNA differences in SCNT animals did not reflect transfer of proteomic components following proteomic analysis. Further study of nuclear-cytoplasmic interactions is needed to illuminate key developmental characteristics of SCNT animals associated with mitochondrial biology.

Global phylogeography of Oithona similis s.l. (Crustacea, Copepoda, Oithonidae) - A cosmopolitan plankton species or a complex of cryptic lineages?

PubMed

Cornils, Astrid; Wend-Heckmann, Britta; Held, Christoph

2017-02-01

Traditionally, many small-sized copepod species are considered to be widespread, bipolar or cosmopolitan. However, these large-scale distribution patterns need to be re-examined in view of increasing evidence of cryptic and pseudo-cryptic speciation in pelagic copepods. Here, we present a phylogeographic study of Oithona similis s.l. populations from the Arctic Ocean, the Southern Ocean and its northern boundaries, the North Atlantic and the Mediterrranean Sea. O. similis s.l. is considered as one of the most abundant species in temperate to polar oceans and acts as an important link in the trophic network between the microbial loop and higher trophic levels such as fish larvae. Two gene fragments were analysed: the mitochondrial cytochrome oxidase c subunit I (COI), and the nuclear ribosomal 28 S genetic marker. Seven distinct, geographically delimitated, mitochondrial lineages could be identified, with divergences among the lineages ranging from 8 to 24%, thus representing most likely cryptic or pseudocryptic species within O. similis s.l. Four lineages were identified within or close to the borders of the Southern Ocean, one lineage in the Arctic Ocean and two lineages in the temperate Northern hemisphere. Surprisingly the Arctic lineage was more closely related to lineages from the Southern hemisphere than to the other lineages from the Northern hemisphere, suggesting that geographic proximity is a rather poor predictor of how closely related the clades are on a genetic level. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondria-Division Inhibitor 1 Protects Against Amyloid-β induced Mitochondrial Fragmentation and Synaptic Damage in Alzheimer's Disease.

PubMed

Reddy, P Hemachandra; Manczak, Maria; Yin, XiangLing

2017-01-01

The purpose our study was to determine the protective effects of mitochondria division inhibitor 1 (Mdivi1) in Alzheimer's disease (AD). Mdivi1 is hypothesized to reduce excessive fragmentation of mitochondria and mitochondrial dysfunction in AD neurons. Very little is known about whether Mdivi1 can confer protective effects in AD. In the present study, we sought to determine the protective effects of Mdivi1 against amyloid-β (Aβ)- and mitochondrial fission protein, dynamin-related protein 1 (Drp1)-induced excessive fragmentation of mitochondria in AD progression. We also studied preventive (Mdivi1+Aβ42) and intervention (Aβ42+Mdivi1) effects against Aβ42 in N2a cells. Using real-time RT-PCR and immunoblotting analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis, and synaptic genes. We also assessed mitochondrial function by measuring H2O2, lipid peroxidation, cytochrome oxidase activity, and mitochondrial ATP. MTT assays were used to assess the cell viability. Aβ42 was found to impair mitochondrial dynamics, lower mitochondrial biogenesis, lower synaptic activity, and lower mitochondrial function. On the contrary, Mdivi1 enhanced mitochondrial fusion activity, lowered fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in Mdivi1-treated cells. Interestingly, Mdivi1 pre- and post-treated cells treated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability, mitochondrial dynamics, mitochondrial biogenesis, and synaptic activity. The protective effects of Mdivi1 were stronger in N2a+Aβ42 pre-treated with Mdivi1, than in N2a+Aβ42 cells than Mdivi1 post-treated cells, indicating that Mdivi1 works better in prevention than treatment in AD like neurons.

Response to comment on "Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage".

PubMed

Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

2013-03-29

Nakagome et al. reanalyzed some of our data and assert that we cannot refute the mitochondrial DNA-based scenario for polar bear evolution. Their single-locus test statistic is strongly affected by introgression and incomplete lineage sorting, whereas our multilocus approaches are better suited to recover the true species relationships. Indeed, our sister-lineage model receives high support in a Bayesian model comparison.

Recent Reticulate Evolution in the Ecologically Dominant Lineage of Coccolithophores

PubMed Central

Bendif, El Mahdi; Probert, Ian; Díaz-Rosas, Francisco; Thomas, Daniela; van den Engh, Ger; Young, Jeremy R.; von Dassow, Peter

2016-01-01

The coccolithophore family Noëlaerhabdaceae contains a number of taxa that are very abundant in modern oceans, including the cosmopolitan bloom-forming Emiliania huxleyi. Introgressive hybridization has been suggested to account for incongruences between nuclear, mitochondrial and plastidial phylogenies of morphospecies within this lineage, but the number of species cultured to date remains rather limited. Here, we present the characterization of 5 new Noëlaerhabdaceae culture strains isolated from samples collected in the south-east Pacific Ocean. These were analyzed morphologically using scanning electron microscopy and phylogenetically by sequencing 5 marker genes (nuclear 18S and 28S rDNA, plastidial tufA, and mitochondrial cox1 and cox3 genes). Morphologically, one of these strains corresponded to Gephyrocapsa ericsonii and the four others to Reticulofenestra parvula. Ribosomal gene sequences were near identical between these new strains, but divergent from G. oceanica, G. muellerae, and E. huxleyi. In contrast to the clear distinction in ribosomal phylogenies, sequences from other genomic compartments clustered with those of E. huxleyi strains with which they share an ecological range (i.e., warm temperate to tropical waters). These data provide strong support for the hypothesis of past (and potentially ongoing) introgressive hybridization within this ecologically important lineage and for the transfer of R. parvula to Gephyrocapsa. These results have important implications for understanding the role of hybridization in speciation in vast ocean meta-populations of phytoplankton. PMID:27252694

Recent Reticulate Evolution in the Ecologically Dominant Lineage of Coccolithophores.

PubMed

Bendif, El Mahdi; Probert, Ian; Díaz-Rosas, Francisco; Thomas, Daniela; van den Engh, Ger; Young, Jeremy R; von Dassow, Peter

2016-01-01

The coccolithophore family Noëlaerhabdaceae contains a number of taxa that are very abundant in modern oceans, including the cosmopolitan bloom-forming Emiliania huxleyi. Introgressive hybridization has been suggested to account for incongruences between nuclear, mitochondrial and plastidial phylogenies of morphospecies within this lineage, but the number of species cultured to date remains rather limited. Here, we present the characterization of 5 new Noëlaerhabdaceae culture strains isolated from samples collected in the south-east Pacific Ocean. These were analyzed morphologically using scanning electron microscopy and phylogenetically by sequencing 5 marker genes (nuclear 18S and 28S rDNA, plastidial tufA, and mitochondrial cox1 and cox3 genes). Morphologically, one of these strains corresponded to Gephyrocapsa ericsonii and the four others to Reticulofenestra parvula. Ribosomal gene sequences were near identical between these new strains, but divergent from G. oceanica, G. muellerae, and E. huxleyi. In contrast to the clear distinction in ribosomal phylogenies, sequences from other genomic compartments clustered with those of E. huxleyi strains with which they share an ecological range (i.e., warm temperate to tropical waters). These data provide strong support for the hypothesis of past (and potentially ongoing) introgressive hybridization within this ecologically important lineage and for the transfer of R. parvula to Gephyrocapsa. These results have important implications for understanding the role of hybridization in speciation in vast ocean meta-populations of phytoplankton.

Discovery of 1-(3-(benzyloxy)pyridin-2-yl)-3-(2-(piperazin-1-yl)ethyl)urea: A new modulator for amyloid beta-induced mitochondrial dysfunction.

PubMed

Elkamhawy, Ahmed; Park, Jung-Eun; Hassan, Ahmed H E; Ra, Hyunhwa; Pae, Ae Nim; Lee, Jiyoun; Park, Beoung-Geon; Moon, Bongjin; Park, Hyun-Mee; Roh, Eun Joo

2017-03-10

Herein, we report a new series of aliphatic substituted pyridyl-urea small molecules synthesized as potential modulators for amyloid beta (Aβ) induced mitochondrial dysfunction. Their blocking activities against Aβ-induced mitochondrial permeability transition pore (mPTP) opening were evaluated by JC-1 assay which measures the change of mitochondrial membrane potential (ΔΨm). The inhibitory activity of sixteen compounds against Aβ-induced mPTP opening was superior or almost similar to that of the standard Cyclosporin A (CsA). Among them, 1-(3-(benzyloxy)pyridin-2-yl)-3-(2-(piperazin-1-yl)ethyl)urea (5x) effectively maintained mitochondrial function and cell viabilities on ATP assay, MTT assay, and ROS assay. Using CDocker algorithm, a molecular docking model presented a plausible binding mode for 5x with cyclophilin D (CypD) receptor as a major component of mPTP. Moreover, hERG and BBB-PAMPA assays presented safe cardiotoxicity and high CNS bioavailability profiles for 5x. Taken as a whole, this report presents compound 5x as a new nonpeptidyl mPTP blocker may hold a promise for further development of Alzheimer's disease (AD) therapeutics. Copyright © 2016. Published by Elsevier Masson SAS.

Metabolic pathways in T cell activation and lineage differentiation.

PubMed

Almeida, Luís; Lochner, Matthias; Berod, Luciana; Sparwasser, Tim

2016-10-01

Recent advances in the field of immunometabolism support the concept that fundamental processes in T cell biology, such as TCR-mediated activation and T helper lineage differentiation, are closely linked to changes in the cellular metabolic programs. Although the major task of the intermediate metabolism is to provide the cell with a constant supply of energy and molecular precursors for the production of biomolecules, the dynamic regulation of metabolic pathways also plays an active role in shaping T cell responses. Key metabolic processes such as glycolysis, fatty acid and mitochondrial metabolism are now recognized as crucial players in T cell activation and differentiation, and their modulation can differentially affect the development of T helper cell lineages. In this review, we describe the diverse metabolic processes that T cells engage during their life cycle from naïve towards effector and memory T cells. We consider in particular how the cellular metabolism may actively support the function of T cells in their different states. Moreover, we discuss how molecular regulators such as mTOR or AMPK link environmental changes to adaptations in the cellular metabolism and elucidate the consequences on T cell differentiation and function. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake.

PubMed

Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

2017-05-01

Mitochondrial calcium ([Ca 2+ ] m ) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca 2+ ] m uptake upon SK channel activation as detected by time lapse mitochondrial Ca 2+ measurements with the Ca 2+ -binding mitochondria-targeted aequorin and FRET-based [Ca 2+ ] m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca 2+ ] m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death.

SK2 channels regulate mitochondrial respiration and mitochondrial Ca2+ uptake

PubMed Central

Honrath, Birgit; Matschke, Lina; Meyer, Tammo; Magerhans, Lena; Perocchi, Fabiana; Ganjam, Goutham K; Zischka, Hans; Krasel, Cornelius; Gerding, Albert; Bakker, Barbara M; Bünemann, Moritz; Strack, Stefan; Decher, Niels; Culmsee, Carsten; Dolga, Amalia M

2017-01-01

Mitochondrial calcium ([Ca2+]m) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca2+]m uptake upon SK channel activation as detected by time lapse mitochondrial Ca2+ measurements with the Ca2+-binding mitochondria-targeted aequorin and FRET-based [Ca2+]m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca2+]m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death. PMID:28282037

Molecular phylogeny of mitochondrial cytochrome b and 12S rRNA sequences in the Felidae: ocelot and domestic cat lineages.

PubMed

Masuda, R; Lopez, J V; Slattery, J P; Yuhki, N; O'Brien, S J

1996-12-01

Molecular phylogeny of the cat family Felidae is derived using two mitochondrial genes, cytochrome b and 12S rRNA. Phylogenetic methods of weighted maximum parsimony and minimum evolution estimated by neighbor-joining are employed to reconstruct topologies among 20 extant felid species. Sequence analyses of 363 bp of cytochrome b and 376 bp of the 12S rRNA genes yielded average pair-wise similarity values between felids ranging from 94 to 99% and from 85 to 99%, respectively. Phylogenetic reconstruction supports more recent, intralineage associations but fails to completely resolve interlineage relationships. Both genes produce a monophyletic group of Felis species but vary in the placement of the pallas cat. The ocelot lineage represents an early divergence within the Felidae, with strong associations between ocelot and margay, Geoffroy's cat and kodkod, and pampas cat and tigrina. Implications of the relative recency of felid evolution, presence of ancestral polymorphisms, and influence of outgroups in placement of the topological root are discussed.

A novel lineage of myoviruses infecting cyanobacteria is widespread in the oceans.

PubMed

Sabehi, Gazalah; Shaulov, Lihi; Silver, David H; Yanai, Itai; Harel, Amnon; Lindell, Debbie

2012-02-07

Viruses infecting bacteria (phages) are thought to greatly impact microbial population dynamics as well as the genome diversity and evolution of their hosts. Here we report on the discovery of a novel lineage of tailed dsDNA phages belonging to the family Myoviridae and describe its first representative, S-TIM5, that infects the ubiquitous marine cyanobacterium, Synechococcus. The genome of this phage encodes an entirely unique set of structural proteins not found in any currently known phage, indicating that it uses lineage-specific genes for virion morphogenesis and represents a previously unknown lineage of myoviruses. Furthermore, among its distinctive collection of replication and DNA metabolism genes, it carries a mitochondrial-like DNA polymerase gene, providing strong evidence for the bacteriophage origin of the mitochondrial DNA polymerase. S-TIM5 also encodes an array of bacterial-like metabolism genes commonly found in phages infecting cyanobacteria including photosynthesis, carbon metabolism and phosphorus acquisition genes. This suggests a common gene pool and gene swapping of cyanophage-specific genes among different phage lineages despite distinct sets of structural and replication genes. All cytosines following purine nucleotides are methylated in the S-TIM5 genome, constituting a unique methylation pattern that likely protects the genome from nuclease degradation. This phage is abundant in the Red Sea and S-TIM5 gene homologs are widespread in the oceans. This unusual phage type is thus likely to be an important player in the oceans, impacting the population dynamics and evolution of their primary producing cyanobacterial hosts.

Staphylococcus aureus Sepsis Induces Early Renal Mitochondrial DNA Repair and Mitochondrial Biogenesis in Mice

PubMed Central

Bartz, Raquel R.; Fu, Ping; Suliman, Hagir B.; Crowley, Stephen D.; MacGarvey, Nancy Chou; Welty-Wolf, Karen; Piantadosi, Claude A.

2014-01-01

Acute kidney injury (AKI) contributes to the high morbidity and mortality of multi-system organ failure in sepsis. However, recovery of renal function after sepsis-induced AKI suggests active repair of energy-producing pathways. Here, we tested the hypothesis in mice that Staphyloccocus aureus sepsis damages mitochondrial DNA (mtDNA) in the kidney and activates mtDNA repair and mitochondrial biogenesis. Sepsis was induced in wild-type C57Bl/6J and Cox-8 Gfp-tagged mitochondrial-reporter mice via intraperitoneal fibrin clots embedded with S. aureus. Kidneys from surviving mice were harvested at time zero (control), 24, or 48 hours after infection and evaluated for renal inflammation, oxidative stress markers, mtDNA content, and mitochondrial biogenesis markers, and OGG1 and UDG mitochondrial DNA repair enzymes. We examined the kidneys of the mitochondrial reporter mice for changes in staining density and distribution. S. aureus sepsis induced sharp amplification of renal Tnf, Il-10, and Ngal mRNAs with decreased renal mtDNA content and increased tubular and glomerular cell death and accumulation of protein carbonyls and 8-OHdG. Subsequently, mtDNA repair and mitochondrial biogenesis was evidenced by elevated OGG1 levels and significant increases in NRF-1, NRF-2, and mtTFA expression. Overall, renal mitochondrial mass, tracked by citrate synthase mRNA and protein, increased in parallel with changes in mitochondrial GFP-fluorescence especially in proximal tubules in the renal cortex and medulla. Sub-lethal S. aureus sepsis thus induces widespread renal mitochondrial damage that triggers the induction of the renal mtDNA repair protein, OGG1, and mitochondrial biogenesis as a conspicuous resolution mechanism after systemic bacterial infection. PMID:24988481

The Effect of Glucose Concentration and Sodium Phenylbutyrate Treatment on Mitochondrial Bioenergetics and ER Stress in 3T3-L1 Adipocytes

PubMed Central

Tanis, Ross M.; Piroli, Gerardo G.; Day, Stani D.; Frizzell, Norma

2016-01-01

While the 3T3-L1 adipocyte model is routinely used for the study of obesity and diabetes, the mitochondrial respiratory profile in normal versus high glucose has not been examined in detail. We matured adipocytes in normal (5 mM) or high (30 mM) glucose and insulin and examined the mitochondrial bioenergetics. We also assessed the requirement for the Unfolded Protein Response (UPR) and ER stress under these conditions. Basal respiration was ∼1.7-fold greater in adipocytes that had matured in 30 mM glucose; however, their ability to increase oxygen consumption in response to stress was impaired. Adipogenesis proceeded in both normal and high glucose with concomitant activation of the UPR, but only high glucose was associated with increased levels of ER stress and mitochondrial stress as observed by parallel increases in CHOP and protein succination. Treatment of adipocytes with sodium phenylbutyrate relieved mitochondrial stress through a reduction in mitochondrial respiration. Our data suggests that mitochondrial stress, protein succination and ER stress are uniquely linked in adipocytes matured in high glucose. PMID:25448036

The mitochondrial elongation factors MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics

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

Liu, Tong; Yu, Rong; Jin, Shao-Bo

2013-11-01

Mitochondria are dynamic organelles whose morphology is regulated by a complex balance of fission and fusion processes, and we still know relatively little about how mitochondrial dynamics is regulated. MIEF1 (also called MiD51) has recently been characterized as a key regulator of mitochondrial dynamics and in this report we explore the functions of its paralog MIEF2 (also called MiD49), to learn to what extent MIEF2 is functionally distinct from MIEF1. We show that MIEF1 and MIEF2 have many functions in common. Both are anchored in the mitochondrial outer membrane, recruit Drp1 from the cytoplasm to the mitochondrial surface and causemore » mitochondrial fusion, and MIEF2, like MIEF1, can interact with Drp1 and hFis1. MIEF1 and MIEF2, however, also differ in certain aspects. MIEF1 and MIEF2 are differentially expressed in human tissues during development. When overexpressed, MIEF2 exerts a stronger fusion-promoting effect than MIEF1, and in line with this, hFis1 and Mff can only partially revert the MIEF2-induced fusion phenotype, whereas MIEF1-induced fusion is reverted to a larger extent by hFis1 and Mff. MIEF2 forms high molecular weight oligomers, while MIEF1 is largely present as a dimer. Furthermore, MIEF1 and MIEF2 use distinct domains for oligomerization: in MIEF1, the region from amino acid residues 109–154 is required, whereas oligomerization of MIEF2 depends on amino acid residues 1 to 49, i.e. the N-terminal end. We also show that oligomerization of MIEF1 is not required for its mitochondrial localization and interaction with Drp1. In conclusion, our data suggest that the mitochondrial regulators MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics. - Highlights: • MIEF1 and MIEF2 recruit Drp1 to mitochondria and cause mitochondrial fusion. • MIEF2, like MIEF1, can interact with Drp1 and hFis1. • MIEF1 and MIEF2 are differentially expressed in human tissues during development. • MIEF2 exerts a stronger fusion

Over-expression of heme oxygenase-1 promotes oxidative mitochondrial damage in rat astroglia.

PubMed

Song, Wei; Su, Haixiang; Song, Sisi; Paudel, Hemant K; Schipper, Hyman M

2006-03-01

Glial heme oxygenase-1 is over-expressed in the CNS of subjects with Alzheimer disease (AD), Parkinson disease (PD) and multiple sclerosis (MS). Up-regulation of HO-1 in rat astroglia has been shown to facilitate iron sequestration by the mitochondrial compartment. To determine whether HO-1 induction promotes mitochondrial oxidative stress, assays for 8-epiPGF(2alpha) (ELISA), protein carbonyls (ELISA) and 8-OHdG (HPLC-EC) were used to quantify oxidative damage to lipids, proteins, and nucleic acids, respectively, in mitochondrial fractions and whole-cell compartments derived from cultured rat astroglia engineered to over-express human (h) HO-1 by transient transfection. Cell viability was assessed by trypan blue exclusion and the MTT assay, and cell proliferation was determined by [3H] thymidine incorporation and total cell counts. In rat astrocytes, hHO-1 over-expression (x 3 days) resulted in significant oxidative damage to mitochondrial lipids, proteins, and nucleic acids, partial growth arrest, and increased cell death. These effects were attenuated by incubation with 1 microM tin mesoporphyrin, a competitive HO inhibitor, or the iron chelator, deferoxamine. Up-regulation of HO-1 engenders oxidative mitochondrial injury in cultured rat astroglia. Heme-derived ferrous iron and carbon monoxide (CO) may mediate the oxidative modification of mitochondrial lipids, proteins and nucleic acids in these cells. Glial HO-1 hyperactivity may contribute to cellular oxidative stress, pathological iron deposition, and bioenergetic failure characteristic of degenerating and inflamed neural tissues and may constitute a rational target for therapeutic intervention in these conditions. Copyright 2005 Wiley-Liss, Inc.

Cdk1, PKCδ and calcineurin-mediated Drp1 pathway contributes to mitochondrial fission-induced cardiomyocyte death

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

Zaja, Ivan; Bai, Xiaowen, E-mail: xibai@mcw.edu; Liu, Yanan

Highlights: • Drp1-mediated increased mitochondrial fission but not fusion is involved the cardiomyocyte death during anoxia-reoxygenation injury. • Reactive oxygen species are upstream initiators of mitochondrial fission. • Increased mitochondrial fission is resulted from Cdk1-, PKCδ-, and calcineurin-mediated Drp1 pathways. - Abstract: Myocardial ischemia–reperfusion (I/R) injury is one of the leading causes of death and disability worldwide. Mitochondrial fission has been shown to be involved in cardiomyocyte death. However, molecular machinery involved in mitochondrial fission during I/R injury has not yet been completely understood. In this study we aimed to investigate molecular mechanisms of controlling activation of dynamin-related protein 1more » (Drp1, a key protein in mitochondrial fission) during anoxia-reoxygenation (A/R) injury of HL1 cardiomyocytes. A/R injury induced cardiomyocyte death accompanied by the increases of mitochondrial fission, reactive oxygen species (ROS) production and activated Drp1 (pSer616 Drp1), and decrease of inactivated Drp1 (pSer637 Drp1) while mitochondrial fusion protein levels were not significantly changed. Blocking Drp1 activity with mitochondrial division inhibitor mdivi1 attenuated cell death, mitochondrial fission, and Drp1 activation after A/R. Trolox, a ROS scavenger, decreased pSer616 Drp1 level and mitochondrial fission after A/R. Immunoprecipitation assay further indicates that cyclin dependent kinase 1 (Cdk1) and protein kinase C isoform delta (PKCδ) bind Drp1, thus increasing mitochondrial fission. Inhibiting Cdk1 and PKCδ attenuated the increases in pSer616 Drp1, mitochondrial fission, and cardiomyocyte death. FK506, a calcineurin inhibitor, blocked the decrease in expression of inactivated pSer637 Drp1 and mitochondrial fission. Our findings reveal the following novel molecular mechanisms controlling mitochondrial fission during A/R injury of cardiomyocytes: (1) ROS are upstream initiators of

Gallic acid targets acute myeloid leukemia via Akt/mTOR-dependent mitochondrial respiration inhibition.

PubMed

Gu, Ruixin; Zhang, Minqin; Meng, Hu; Xu, Dandan; Xie, Yonghua

2018-06-05

Gallic acid is one of the many phenolic acids that can be found in dietary substances and traditional medicine herbs. The anti-cancer activities of gallic acid have been shown in various cancers but its underlying molecular mechanisms are not well understood. In this study, we show Akt/mammalian target of rapamycin (mTOR)-dependent inhibition of mitochondrial respiration as a mechanism of gallic acid's action in acute myeloid leukemia (AML). Gallic acid significantly induces apoptosis of AML cell lines, primary mononuclear cells (MNC) and CD34 stem/progenitors isolated form AML patients via caspase-dependent pathway. It also significantly enhances two standard AML chemotherapeutic agents' efficacy in vitro cell culture system and in vivo xenograft model. Gallic acid inhibits dose- and time-dependent mitochondrial respiration, leading to decreased ATP production and oxidative stress. Overexpression of constitutively active Akt restores gallic acid-mediated inhibition of mTOR signaling, mitochondrial dysfunction, energy crisis and apoptosis. Our results demonstrate that mitochondrial respiration inhibition by gallic acid is a consequence of Akt/mTOR signaling suppression. Our findings suggest that combination therapy with gallic acid may enhance antileukemic efficacy of standard chemotherapeutic agents in AML. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Y-chromosome lineages in Cabo Verde Islands witness the diverse geographic origin of its first male settlers.

PubMed

Gonçalves, Rita; Rosa, Alexandra; Freitas, Ana; Fernandes, Ana; Kivisild, Toomas; Villems, Richard; Brehm, António

2003-11-01

The Y-chromosome haplogroup composition of the population of the Cabo Verde Archipelago was profiled by using 32 single-nucleotide polymorphism markers and compared with potential source populations from Iberia, west Africa, and the Middle East. According to the traditional view, the major proportion of the founding population of Cabo Verde was of west African ancestry with the addition of a minor fraction of male colonizers from Europe. Unexpectedly, more than half of the paternal lineages (53.5%) of Cabo Verdeans clustered in haplogroups I, J, K, and R1, which are characteristic of populations of Europe and the Middle East, while being absent in the probable west African source population of Guiné-Bissau. Moreover, a high frequency of J* lineages in Cabo Verdeans relates them more closely to populations of the Middle East and probably provides the first genetic evidence of the legacy of the Jews. In addition, the considerable proportion (20.5%) of E3b(xM81) lineages indicates a possible gene flow from the Middle East or northeast Africa, which, at least partly, could be ascribed to the Sephardic Jews. In contrast to the predominance of west African mitochondrial DNA haplotypes in their maternal gene pool, the major west African Y-chromosome lineage E3a was observed only at a frequency of 15.9%. Overall, these results indicate that gene flow from multiple sources and various sex-specific patterns have been important in the formation of the genomic diversity in the Cabo Verde islands.

The History of Slavs Inferred from Complete Mitochondrial Genome Sequences

PubMed Central

Mielnik-Sikorska, Marta; Daca, Patrycja; Malyarchuk, Boris; Derenko, Miroslava; Skonieczna, Katarzyna; Perkova, Maria; Dobosz, Tadeusz; Grzybowski, Tomasz

2013-01-01

To shed more light on the processes leading to crystallization of a Slavic identity, we investigated variability of complete mitochondrial genomes belonging to haplogroups H5 and H6 (63 mtDNA genomes) from the populations of Eastern and Western Slavs, including new samples of Poles, Ukrainians and Czechs presented here. Molecular dating implies formation of H5 approximately 11.5–16 thousand years ago (kya) in the areas of southern Europe. Within ancient haplogroup H6, dated at around 15–28 kya, there is a subhaplogroup H6c, which probably survived the last glaciation in Europe and has undergone expansion only 3–4 kya, together with the ancestors of some European groups, including the Slavs, because H6c has been detected in Czechs, Poles and Slovaks. Detailed analysis of complete mtDNAs allowed us to identify a number of lineages that seem specific for Central and Eastern Europe (H5a1f, H5a2, H5a1r, H5a1s, H5b4, H5e1a, H5u1, some subbranches of H5a1a and H6a1a9). Some of them could possibly be traced back to at least ∼4 kya, which indicates that some of the ancestors of today's Slavs (Poles, Czechs, Slovaks, Ukrainians and Russians) inhabited areas of Central and Eastern Europe much earlier than it was estimated on the basis of archaeological and historical data. We also sequenced entire mitochondrial genomes of several non-European lineages (A, C, D, G, L) found in contemporary populations of Poland and Ukraine. The analysis of these haplogroups confirms the presence of Siberian (C5c1, A8a1) and Ashkenazi-specific (L2a1l2a) mtDNA lineages in Slavic populations. Moreover, we were able to pinpoint some lineages which could possibly reflect the relatively recent contacts of Slavs with nomadic Altaic peoples (C4a1a, G2a, D5a2a1a1). PMID:23342138

Next-Generation Sequencing of Two Mitochondrial Genomes from Family Pompilidae (Hymenoptera: Vespoidea) Reveal Novel Patterns of Gene Arrangement

PubMed Central

Chen, Peng-Yan; Zheng, Bo-Ying; Liu, Jing-Xian; Wei, Shu-Jun

2016-01-01

Animal mitochondrial genomes have provided large and diverse datasets for evolutionary studies. Here, the first two representative mitochondrial genomes from the family Pompilidae (Hymenoptera: Vespoidea) were determined using next-generation sequencing. The sequenced region of these two mitochondrial genomes from the species Auplopus sp. and Agenioideus sp. was 16,746 bp long with an A + T content of 83.12% and 16,596 bp long with an A + T content of 78.64%, respectively. In both species, all of the 37 typical mitochondrial genes were determined. The secondary structure of tRNA genes and rRNA genes were predicted and compared with those of other insects. Atypical trnS1 using abnormal anticodons TCT and lacking D-stem pairings was identified. There were 49 helices belonging to six domains in rrnL and 30 helices belonging to three domains in rrns present. Compared with the ancestral organization, four and two tRNA genes were rearranged in mitochondrial genomes of Auplopus and Agenioideus, respectively. In both species, trnM was shuffled upstream of the trnI-trnQ-trnM cluster, and trnA was translocated from the cluster trnA-trnR-trnN-trnS1-trnE-trnF to the region between nad1 and trnL1, which is novel to the Vespoidea. In Auplopus, the tRNA cluster trnW-trnC-trnY was shuffled to trnW-trnY-trnC. Phylogenetic analysis within Vespoidea revealed that Pompilidae and Mutillidae formed a sister lineage, and then sistered Formicidae. The genomes presented in this study have enriched the knowledge base of molecular markers, which is valuable in respect to studies about the gene rearrangement mechanism, genomic evolutionary processes and phylogeny of Hymenoptera. PMID:27727175

Evolutionary Convergence of Cell-Specific Gene Expression in Independent Lineages of C4 Grasses1[W][OPEN

PubMed Central

John, Christopher R.; Smith-Unna, Richard D.; Woodfield, Helen; Covshoff, Sarah; Hibberd, Julian M.

2014-01-01

Leaves of almost all C4 lineages separate the reactions of photosynthesis into the mesophyll (M) and bundle sheath (BS). The extent to which messenger RNA profiles of M and BS cells from independent C4 lineages resemble each other is not known. To address this, we conducted deep sequencing of RNA isolated from the M and BS of Setaria viridis and compared these data with publicly available information from maize (Zea mays). This revealed a high correlation (r = 0.89) between the relative abundance of transcripts encoding proteins of the core C4 pathway in M and BS cells in these species, indicating significant convergence in transcript accumulation in these evolutionarily independent C4 lineages. We also found that the vast majority of genes encoding proteins of the C4 cycle in S. viridis are syntenic to homologs used by maize. In both lineages, 122 and 212 homologous transcription factors were preferentially expressed in the M and BS, respectively. Sixteen shared regulators of chloroplast biogenesis were identified, 14 of which were syntenic homologs in maize and S. viridis. In sorghum (Sorghum bicolor), a third C4 grass, we found that 82% of these trans-factors were also differentially expressed in either M or BS cells. Taken together, these data provide, to our knowledge, the first quantification of convergence in transcript abundance in the M and BS cells from independent lineages of C4 grasses. Furthermore, the repeated recruitment of syntenic homologs from large gene families strongly implies that parallel evolution of both structural genes and trans-factors underpins the polyphyletic evolution of this highly complex trait in the monocotyledons. PMID:24676859

Melatonin prevents abnormal mitochondrial dynamics resulting from the neurotoxicity of cadmium by blocking calcium-dependent translocation of Drp1 to the mitochondria.

PubMed

Xu, Shangcheng; Pi, Huifeng; Zhang, Lei; Zhang, Nixian; Li, YuMing; Zhang, Huiliang; Tang, Ju; Li, Huijuan; Feng, Min; Deng, Ping; Guo, Pan; Tian, Li; Xie, Jia; He, Mindi; Lu, Yonghui; Zhong, Min; Zhang, Yanwen; Wang, Wang; Reiter, Russel J; Yu, Zhengping; Zhou, Zhou

2016-04-01

Cadmium (Cd) is a persistent environmental toxin and occupational pollutant that is considered to be a potential risk factor in the development of neurodegenerative diseases. Abnormal mitochondrial dynamics are increasingly implicated in mitochondrial damage in various neurological pathologies. The aim of this study was to investigate whether the disturbance of mitochondrial dynamics contributed to Cd-induced neurotoxicity and whether melatonin has any neuroprotective properties. After cortical neurons were exposed to 10 μM cadmium chloride (CdCl2 ) for various periods (0, 3, 6, 12, and 24 hr), the morphology of their mitochondria significantly changed from the normal tubular networks into punctuated structures within 3 hr. Following this pronounced mitochondrial fragmentation, Cd treatment led to signs of mitochondrial dysfunction, including excess reactive oxygen species (ROS) production, decreased ATP content, and mitochondrial membrane potential (▵Ψm) loss. However, 1 mM melatonin pretreatment efficiently attenuated the Cd-induced mitochondrial fragmentation, which improved the turnover of mitochondrial function. In the brain tissues of rats that were intraperitoneally given 1 mg/kg CdCl2 for 7 days, melatonin also ameliorated excessive mitochondrial fragmentation and mitochondrial damage in vivo. Melatonin's protective effects were attributed to its roles in preventing cytosolic calcium ([Ca(2+) ]i ) overload, which blocked the recruitment of Drp1 from the cytoplasm to the mitochondria. Taken together, our results are the first to demonstrate that abnormal mitochondrial dynamics is involved in cadmium-induced neurotoxicity. Melatonin has significant pharmacological potential in protecting against the neurotoxicity of Cd by blocking the disbalance of mitochondrial fusion and fission. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Extensive Variation and Sub-Structuring in Lineage A mtDNA in Indian Sheep: Genetic Evidence for Domestication of Sheep in India

PubMed Central

Singh, Sachin; Kumar Jr, Satish; Kolte, Atul P.; Kumar, Satish

2013-01-01

Previous studies on mitochondrial DNA analysis of sheep from different regions of the world have revealed the presence of two major- A and B, and three minor- C, D and E maternal lineages. Lineage A is more frequent in Asia and lineage B is more abundant in regions other than Asia. We have analyzed mitochondrial DNA sequences of 330 sheep from 12 different breeds of India. Neighbor-joining analysis revealed lineage A, B and C in Indian sheep. Surprisingly, multidimensional scaling plot based on FST values of control region of mtDNA sequences showed significant breed differentiation in contrast to poor geographical structuring reported earlier in this species. The breed differentiation in Indian sheep was essentially due to variable contribution of two major lineages to different breeds, and sub- structuring of lineage A, possibly the latter resulting from genetic drift. Nucleotide diversity of this lineage was higher in Indian sheep (0.014 ± 0.007) as compared to that of sheep from other regions of the world (0.009 ± 0.005 to 0.01 ± 0.005). Reduced median network analysis of control region and cytochrome b gene sequences of Indian sheep when analyzed along with available published sequences of sheep from other regions of the world showed that several haplotypes of lineage A were exclusive to Indian sheep. Given the high nucleotide diversity in Indian sheep and the poor sharing of lineage A haplotypes between Indian and non-Indian sheep, we propose that lineage A sheep has also been domesticated in the east of Near East, possibly in Indian sub-continent. Finally, our data provide support that lineage B and additional lineage A haplotypes of sheep might have been introduced to Indian sub-continent from Near East, probably by ancient sea trade route. PMID:24244282

Phosphatidic acid (PA)-preferring phospholipase A1 regulates mitochondrial dynamics.

PubMed

Baba, Takashi; Kashiwagi, Yuriko; Arimitsu, Nagisa; Kogure, Takeshi; Edo, Ayumi; Maruyama, Tomohiro; Nakao, Kazuki; Nakanishi, Hiroki; Kinoshita, Makoto; Frohman, Michael A; Yamamoto, Akitsugu; Tani, Katsuko

2014-04-18

Recent studies have suggested that phosphatidic acid (PA), a cone-shaped phospholipid that can generate negative curvature of lipid membranes, participates in mitochondrial fusion. However, precise mechanisms underling the production and consumption of PA on the mitochondrial surface are not fully understood. Phosphatidic acid-preferring phospholipase A1 (PA-PLA1)/DDHD1 is the first identified intracellular phospholipase A1 and preferentially hydrolyzes PA in vitro. Its cellular and physiological functions have not been elucidated. In this study, we show that PA-PLA1 regulates mitochondrial dynamics. PA-PLA1, when ectopically expressed in HeLa cells, induced mitochondrial fragmentation, whereas its depletion caused mitochondrial elongation. The effects of PA-PLA1 on mitochondrial morphology appear to counteract those of MitoPLD, a mitochondrion-localized phospholipase D that produces PA from cardiolipin. Consistent with high levels of expression of PA-PLA1 in testis, PA-PLA1 knock-out mice have a defect in sperm formation. In PA-PLA1-deficient sperm, the mitochondrial structure is disorganized, and an abnormal gap structure exists between the middle and principal pieces. A flagellum is bent at that position, leading to a loss of motility. Our results suggest a possible mechanism of PA regulation of the mitochondrial membrane and demonstrate an in vivo function of PA-PLA1 in the organization of mitochondria during spermiogenesis.

Crimean-Congo hemorrhagic fever virus lineages Europe 1 and Europe 2 in Bulgarian ticks.

PubMed

Panayotova, Elitsa; Papa, Anna; Trifonova, Iva; Christova, Iva

2016-07-01

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne human viral disease with fatality rate up to 30%. Two genetic lineages of CCHF virus (CCHFV) are present in Europe - lineage Europe 1 which contains pathogenic CCHFV strains, and lineage Europe 2 consisting of AP92 and AP92-like strains. In order to investigate CCHFV distribution and potential risk for humans, ticks were collected from livestock in the five districts where CCHF cases have been reported in the last five years in Bulgaria. CCHFV lineage Europe 1 was detected in 39 of 623 Hyalomma marginatum ticks (6.3%; range per village 2.7-15.2%), while CCHFV lineage Europe 2 was detected for the first time in Bulgaria in 49 of 415 Rhipicephalus sanguineus sensu lato ticks (11.8%; range 0-58.3%). The present study shows that both Europe 1 and Europe 2 CCHFV lineages are present in Bulgaria. The pathogenic role of the AP92-like strains remains to be elucidated. Copyright © 2016 Elsevier GmbH. All rights reserved.

Evolutionary history of freshwater sculpins, genus Cottus (Teleostei; Cottidae) and related taxa, as inferred from mitochondrial DNA phylogeny.

PubMed

Yokoyama, Ryota; Goto, Akira

2005-09-01

The freshwater sculpins, genus Cottus (Teleostei; Cottidae), comprise bottom-dwelling fishes that exhibit various life-history styles, having radiated throughout Northern Hemisphere freshwater habitats. The phylogenetic relationships among Cottus and related taxa were estimated from mitochondrial DNA 12S rRNA and control region (CR) sequences, the freshwater sculpins examined falling into five lineages (A-E). Lineage A consisted of Trachidermus fasciatus and C. kazika, both having a catadromous life-history. The remaining species (lineages B-E) spawn in freshwater habitats regardless of life-history (amphidromous, lacustrine or fluvial), suggesting that the various life-history types post-dated a common ancestor of lineages B-E. Molecular clock estimates suggested a Pliocene-Pleistocene radiation (or Miocene-Pliocene from the alternative clock) of lineages B-E. In eastern Eurasia, speciation with life-history changes to amphidromous or fluvial styles has apparently occurred independently in some lineages, as a general pattern. Mitochondrial DNA CR phylogeny showed the monophyletic Baikalian cottoids (Cottoidei) to be nested within Cottus and Trachidermus, suggesting that the former ecologically and morphologically divergent cottoids may have originated from a single lineage which invaded the ancient lake.

The effect of glucose concentration and sodium phenylbutyrate treatment on mitochondrial bioenergetics and ER stress in 3T3-L1 adipocytes.

PubMed

Tanis, Ross M; Piroli, Gerardo G; Day, Stani D; Frizzell, Norma

2015-01-01

While the 3T3-L1 adipocyte model is routinely used for the study of obesity and diabetes, the mitochondrial respiratory profile in normal versus high glucose has not been examined in detail. We matured adipocytes in normal (5mM) or high (30 mM) glucose and insulin and examined the mitochondrial bioenergetics. We also assessed the requirement for the Unfolded Protein Response (UPR) and ER stress under these conditions. Basal respiration was ~1.7-fold greater in adipocytes that had matured in 30 mM glucose; however, their ability to increase oxygen consumption in response to stress was impaired. Adipogenesis proceeded in both normal and high glucose with concomitant activation of the UPR, but only high glucose was associated with increased levels of ER stress and mitochondrial stress as observed by parallel increases in CHOP and protein succination. Treatment of adipocytes with sodium phenylbutyrate relieved mitochondrial stress through a reduction in mitochondrial respiration. Our data suggests that mitochondrial stress, protein succination and ER stress are uniquely linked in adipocytes matured in high glucose. Copyright © 2014 Elsevier B.V. All rights reserved.

Heme oxygenase-1 regulates mitochondrial quality control in the heart

PubMed Central

Hull, Travis D.; Boddu, Ravindra; Guo, Lingling; Tisher, Cornelia C.; Traylor, Amie M.; Patel, Bindiya; Joseph, Reny; Prabhu, Sumanth D.; Suliman, Hagir B.; Piantadosi, Claude A.; George, James F.

2016-01-01

The cardioprotective inducible enzyme heme oxygenase-1 (HO-1) degrades prooxidant heme into equimolar quantities of carbon monoxide, biliverdin, and iron. We hypothesized that HO-1 mediates cardiac protection, at least in part, by regulating mitochondrial quality control. We treated WT and HO-1 transgenic mice with the known mitochondrial toxin, doxorubicin (DOX). Relative to WT mice, mice globally overexpressing human HO-1 were protected from DOX-induced dilated cardiomyopathy, cardiac cytoarchitectural derangement, and infiltration of CD11b+ mononuclear phagocytes. Cardiac-specific overexpression of HO-1 ameliorated DOX-mediated dilation of the sarcoplasmic reticulum as well as mitochondrial disorganization in the form of mitochondrial fragmentation and increased numbers of damaged mitochondria in autophagic vacuoles. HO-1 overexpression promotes mitochondrial biogenesis by upregulating protein expression of NRF1, PGC1α, and TFAM, which was inhibited in WT animals treated with DOX. Concomitantly, HO-1 overexpression inhibited the upregulation of the mitochondrial fission mediator Fis1 and resulted in increased expression of the fusion mediators, Mfn1 and Mfn2. It also prevented dynamic changes in the levels of key mediators of the mitophagy pathway, PINK1 and parkin. Therefore, these findings suggest that HO-1 has a novel role in protecting the heart from oxidative injury by regulating mitochondrial quality control. PMID:27110594

Positioning the red deer (Cervus elaphus) hunted by the Tyrolean Iceman into a mitochondrial DNA phylogeny.

PubMed

Olivieri, Cristina; Marota, Isolina; Rizzi, Ermanno; Ermini, Luca; Fusco, Letizia; Pietrelli, Alessandro; De Bellis, Gianluca; Rollo, Franco; Luciani, Stefania

2014-01-01

In the last years several phylogeographic studies of both extant and extinct red deer populations have been conducted. Three distinct mitochondrial lineages (western, eastern and North-African/Sardinian) have been identified reflecting different glacial refugia and postglacial recolonisation processes. However, little is known about the genetics of the Alpine populations and no mitochondrial DNA sequences from Alpine archaeological specimens are available. Here we provide the first mitochondrial sequences of an Alpine Copper Age Cervus elaphus. DNA was extracted from hair shafts which were part of the remains of the clothes of the glacier mummy known as the Tyrolean Iceman or Ötzi (5,350-5,100 years before present). A 2,297 base pairs long fragment was sequenced using a mixed sequencing procedure based on PCR amplifications and 454 sequencing of pooled amplification products. We analyzed the phylogenetic relationships of the Alpine Copper Age red deer's haplotype with haplotypes of modern and ancient European red deer. The phylogenetic analyses showed that the haplotype of the Alpine Copper Age red deer falls within the western European mitochondrial lineage in contrast with the current populations from the Italian Alps belonging to the eastern lineage. We also discussed the phylogenetic relationships of the Alpine Copper Age red deer with the populations from Mesola Wood (northern Italy) and Sardinia.

Multifunctional Mitochondrial Epac1 Controls Myocardial Cell Death.

PubMed

Fazal, Loubina; Laudette, Marion; Paula-Gomes, Sílvia; Pons, Sandrine; Conte, Caroline; Tortosa, Florence; Sicard, Pierre; Sainte-Marie, Yannis; Bisserier, Malik; Lairez, Olivier; Lucas, Alexandre; Roy, Jérôme; Ghaleh, Bijan; Fauconnier, Jérémy; Mialet-Perez, Jeanne; Lezoualc'h, Frank

2017-02-17

Although the second messenger cyclic AMP (cAMP) is physiologically beneficial in the heart, it largely contributes to cardiac disease progression when dysregulated. Current evidence suggests that cAMP is produced within mitochondria. However, mitochondrial cAMP signaling and its involvement in cardiac pathophysiology are far from being understood. To investigate the role of MitEpac1 (mitochondrial exchange protein directly activated by cAMP 1) in ischemia/reperfusion injury. We show that Epac1 (exchange protein directly activated by cAMP 1) genetic ablation ( Epac1 -/- ) protects against experimental myocardial ischemia/reperfusion injury with reduced infarct size and cardiomyocyte apoptosis. As observed in vivo, Epac1 inhibition prevents hypoxia/reoxygenation-induced adult cardiomyocyte apoptosis. Interestingly, a deleted form of Epac1 in its mitochondrial-targeting sequence protects against hypoxia/reoxygenation-induced cell death. Mechanistically, Epac1 favors Ca 2+ exchange between the endoplasmic reticulum and the mitochondrion, by increasing interaction with a macromolecular complex composed of the VDAC1 (voltage-dependent anion channel 1), the GRP75 (chaperone glucose-regulated protein 75), and the IP3R1 (inositol-1,4,5-triphosphate receptor 1), leading to mitochondrial Ca 2+ overload and opening of the mitochondrial permeability transition pore. In addition, our findings demonstrate that MitEpac1 inhibits isocitrate dehydrogenase 2 via the mitochondrial recruitment of CaMKII (Ca 2+ /calmodulin-dependent protein kinase II), which decreases nicotinamide adenine dinucleotide phosphate hydrogen synthesis, thereby, reducing the antioxidant capabilities of the cardiomyocyte. Our results reveal the existence, within mitochondria, of different cAMP-Epac1 microdomains that control myocardial cell death. In addition, our findings suggest Epac1 as a promising target for the treatment of ischemia-induced myocardial damage. © 2017 American Heart Association, Inc.

mTOR inhibition alleviates mitochondrial disease in a mouse model of Leigh syndrome.

PubMed

Johnson, Simon C; Yanos, Melana E; Kayser, Ernst-Bernhard; Quintana, Albert; Sangesland, Maya; Castanza, Anthony; Uhde, Lauren; Hui, Jessica; Wall, Valerie Z; Gagnidze, Arni; Oh, Kelly; Wasko, Brian M; Ramos, Fresnida J; Palmiter, Richard D; Rabinovitch, Peter S; Morgan, Philip G; Sedensky, Margaret M; Kaeberlein, Matt

2013-12-20

Mitochondrial dysfunction contributes to numerous health problems, including neurological and muscular degeneration, cardiomyopathies, cancer, diabetes, and pathologies of aging. Severe mitochondrial defects can result in childhood disorders such as Leigh syndrome, for which there are no effective therapies. We found that rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, robustly enhances survival and attenuates disease progression in a mouse model of Leigh syndrome. Administration of rapamycin to these mice, which are deficient in the mitochondrial respiratory chain subunit Ndufs4 [NADH dehydrogenase (ubiquinone) Fe-S protein 4], delays onset of neurological symptoms, reduces neuroinflammation, and prevents brain lesions. Although the precise mechanism of rescue remains to be determined, rapamycin induces a metabolic shift toward amino acid catabolism and away from glycolysis, alleviating the buildup of glycolytic intermediates. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.

Complete Mitochondrial Genomes of New Zealand’s First Dogs

PubMed Central

Greig, Karen; Boocock, James; Prost, Stefan; Horsburgh, K. Ann; Jacomb, Chris; Walter, Richard; Matisoo-Smith, Elizabeth

2015-01-01

Dogs accompanied people in their migrations across the Pacific Ocean and ultimately reached New Zealand, which is the southern-most point of their oceanic distribution, around the beginning of the fourteenth century AD. Previous ancient DNA analyses of mitochondrial control region sequences indicated the New Zealand dog population included two lineages. We sequenced complete mitochondrial genomes of fourteen dogs from the colonisation era archaeological site of Wairau Bar and found five closely-related haplotypes. The limited number of mitochondrial lineages present at Wairau Bar suggests that the founding population may have comprised only a few dogs; or that the arriving dogs were closely related. For populations such as that at Wairau Bar, which stemmed from relatively recent migration events, control region sequences have insufficient power to address questions about population structure and founding events. Sequencing mitogenomes provided the opportunity to observe sufficient diversity to discriminate between individuals that would otherwise be assigned the same haplotype and to clarify their relationships with each other. Our results also support the proposition that at least one dispersal of dogs into the Pacific was via a south-western route through Indonesia. PMID:26444283

Aluminium induced oxidative stress results in decreased mitochondrial biogenesis via modulation of PGC-1α expression.

PubMed

Sharma, Deep Raj; Sunkaria, Aditya; Wani, Willayat Yousuf; Sharma, Reeta Kumari; Kandimalla, Ramesh J L; Bal, Amanjit; Gill, Kiran Dip

2013-12-01

The present investigation was carried out to elucidate a possible molecular mechanism related to the effects of aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of Peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α) and its downstream targets i.e. Nuclear respiratory factor-1(NRF-1), Nuclear respiratory factor-2(NRF-2) and Mitochondrial transcription factor A (Tfam) in mitochondrial biogenesis. Aluminium lactate (10mg/kgb.wt./day) was administered intragastrically to rats for 12 weeks. After 12 weeks of exposure, we found an increase in ROS levels, mitochondrial DNA oxidation and decrease in citrate synthase activity in the Hippocampus (HC) and Corpus striatum (CS) regions of rat brain. On the other hand, there was a decrease in the mRNA levels of the mitochondrial encoded subunits-NADH dehydrogenase (ND) subunits i.e. ND1, ND2, ND3, Cytochrome b (Cytb), Cytochrome oxidase (COX) subunits i.e. COX1, COX3, ATP synthase (ATPase) subunit 6 along with reduced expression of nuclear encoded subunits COX4, COX5A, COX5B of Electron transport chain (ETC). Besides, a decrease in mitochondrial DNA copy number and mitochondrial content in both regions of rat brain was observed. The PGC-1α was down-regulated in aluminium treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α in aluminium treated rats. Electron microscopy results revealed a significant increase in the mitochondrial swelling, loss of cristae, chromatin condensation and decreases in mitochondrial number in case of aluminium treated rats as compared to control. So, PGC-1α seems to be a potent target for aluminium neurotoxicity, which makes it an almost ideal target to control or limit the damage that has been associated with the defective mitochondrial function seen in neurodegenerative diseases. © 2013.

CDK1 enhances mitochondrial bioenergetics for radiation-induced DNA repair

DOE PAGES

Qin, Lili; Fan, Ming; Candas, Demet; ...

2015-12-06

Nuclear DNA repair capacity is a critical determinant of cell fate under genotoxic stress conditions. DNA repair is a well-defined energy-consuming process. However, it is unclear how DNA repair is fueled and whether mitochondrial energy production contributes to nuclear DNA repair. Here, we report a dynamic enhancement of oxygen consumption and mitochondrial ATP generation in irradiated normal cells, paralleled with increased mitochondrial relocation of the cell-cycle kinase CDK1 and nuclear DNA repair. The basal and radiation-induced mitochondrial ATP generation is reduced significantly in cells harboring CDK1 phosphorylation-deficient mutant complex I subunits. Similarly, mitochondrial ATP generation and nuclear DNA repair aremore » also compromised severely in cells harboring mitochondrially targeted, kinase-deficient CDK1. These findings demonstrate a mechanism governing the communication between mitochondria and the nucleus by which CDK1 boosts mitochondrial bioenergetics to meet the increased cellular fuel demand for DNA repair and cell survival under genotoxic stress conditions.« less

Homozygous YME1L1 mutation causes mitochondriopathy with optic atrophy and mitochondrial network fragmentation.

PubMed

Hartmann, Bianca; Wai, Timothy; Hu, Hao; MacVicar, Thomas; Musante, Luciana; Fischer-Zirnsak, Björn; Stenzel, Werner; Gräf, Ralph; van den Heuvel, Lambert; Ropers, Hans-Hilger; Wienker, Thomas F; Hübner, Christoph; Langer, Thomas; Kaindl, Angela M

2016-08-06

Mitochondriopathies often present clinically as multisystemic disorders of primarily high-energy consuming organs. Assembly, turnover, and surveillance of mitochondrial proteins are essential for mitochondrial function and a key task of AAA family members of metalloproteases. We identified a homozygous mutation in the nuclear encoded mitochondrial escape 1-like 1 gene YME1L1, member of the AAA protease family, as a cause of a novel mitochondriopathy in a consanguineous pedigree of Saudi Arabian descent. The homozygous missense mutation, located in a highly conserved region in the mitochondrial pre-sequence, inhibits cleavage of YME1L1 by the mitochondrial processing peptidase, which culminates in the rapid degradation of YME1L1 precursor protein. Impaired YME1L1 function causes a proliferation defect and mitochondrial network fragmentation due to abnormal processing of OPA1. Our results identify mutations in YME1L1 as a cause of a mitochondriopathy with optic nerve atrophy highlighting the importance of YME1L1 for mitochondrial functionality in humans.

Homozygous YME1L1 mutation causes mitochondriopathy with optic atrophy and mitochondrial network fragmentation

PubMed Central

Hartmann, Bianca; Wai, Timothy; Hu, Hao; MacVicar, Thomas; Musante, Luciana; Fischer-Zirnsak, Björn; Stenzel, Werner; Gräf, Ralph; van den Heuvel, Lambert; Ropers, Hans-Hilger; Wienker, Thomas F; Hübner, Christoph; Langer, Thomas; Kaindl, Angela M

2016-01-01

Mitochondriopathies often present clinically as multisystemic disorders of primarily high-energy consuming organs. Assembly, turnover, and surveillance of mitochondrial proteins are essential for mitochondrial function and a key task of AAA family members of metalloproteases. We identified a homozygous mutation in the nuclear encoded mitochondrial escape 1-like 1 gene YME1L1, member of the AAA protease family, as a cause of a novel mitochondriopathy in a consanguineous pedigree of Saudi Arabian descent. The homozygous missense mutation, located in a highly conserved region in the mitochondrial pre-sequence, inhibits cleavage of YME1L1 by the mitochondrial processing peptidase, which culminates in the rapid degradation of YME1L1 precursor protein. Impaired YME1L1 function causes a proliferation defect and mitochondrial network fragmentation due to abnormal processing of OPA1. Our results identify mutations in YME1L1 as a cause of a mitochondriopathy with optic nerve atrophy highlighting the importance of YME1L1 for mitochondrial functionality in humans. DOI: http://dx.doi.org/10.7554/eLife.16078.001 PMID:27495975

The mitochondrial genome of Polistes jokahamae and a phylogenetic analysis of the Vespoidea (Insecta: Hymenoptera).

PubMed

Song, Sheng-Nan; Chen, Peng-Yan; Wei, Shu-Jun; Chen, Xue-Xin

2016-07-01

The mitochondrial genome sequence of Polistes jokahamae (Radoszkowski, 1887) (Hymenoptera: Vespidae) (GenBank accession no. KR052468) was sequenced. The current length with partial A + T-rich region of this mitochondrial genome is 16,616 bp. All the typical mitochondrial genes were sequenced except for three tRNAs (trnI, trnQ, and trnY) located between the A + T-rich region and nad2. At least three rearrangement events occurred in the sequenced region compared with the pupative ancestral arrangement of insects, corresponding to the shuffling of trnK and trnD, translocation or remote inversion of tnnY and translocation of trnL1. All protein-coding genes start with ATN codons. Eleven, one, and another one protein-coding genes stop with termination codon TAA, TA, and T, respectively. Phylogenetic analysis using the Bayesian method based on all codon positions of the 13 protein-coding genes supports the monophyly of Vespidae and Formicidae. Within the Formicidae, the Myrmicinae and Formicinae form a sister lineage and then sister to the Dolichoderinae, while within the Vespidae, the Eumeninae is sister to the lineage of Vespinae + Polistinae.

Complete mitochondrial genome of the endophytic fungus Pestalotiopsis fici: features and evolution.

PubMed

Zhang, Shu; Wang, Xiu-Na; Zhang, Xiao-Ling; Liu, Xing-Zhong; Zhang, Yong-Jie

2017-02-01

Endophytic fungi (EF) live within plants and have profound impacts on plant communities. They are astonishingly diverse but poorly studied at the genome level. Herein, we assembled the mitochondrial genome (mitogenome) of the EF Pestalotiopsis fici, annotated and compared it with those of other relatives to better understand the evolution of the EF lineage. Except for standard fungal mitochondrial genes, the 69,529-bp circular mitogenome of P. fici harbors 18 introns acquired possibly through lateral transfer from other fungi and nine free-standing open reading frames with some scarcely seen in fungal mitogenomes. BLAST analysis detected no obvious duplication events of large fragments between mitochondrial and nuclear genomes of the fungus. Transcription analyses validated the expression of all mitochondrial genes, while most genes showed higher expression on rice than in two other media. The mitogenome of P. fici is highly syntenic with the Xylariales species Annulohypoxylon stygium and the endophyte Epichloe festucae var. lolii, but lacks synteny with another endophyte Penicillium polonicum. This study reports the first mitogenome of Pestalotiopsis and the third published mitogenome from an EF and provides insights into the evolution of the EF lineage.

Critical contribution of RIPK1 mediated mitochondrial dysfunction and oxidative stress to compression-induced rat nucleus pulposus cells necroptosis and apoptosis.

PubMed

Chen, Songfeng; Lv, Xiao; Hu, Binwu; Zhao, Lei; Li, Shuai; Li, Zhiliang; Qing, Xiangcheng; Liu, Hongjian; Xu, Jianzhong; Shao, Zengwu

2018-04-28

The aim of this study was to investigate whether RIPK1 mediated mitochondrial dysfunction and oxidative stress contributed to compression-induced nucleus pulposus (NP) cells necroptosis and apoptosis, together with the interplay relationship between necroptosis and apoptosis in vitro. Rat NP cells underwent various periods of 1.0 MPa compression. To determine whether compression affected mitochondrial function, we evaluated the mitochondrial membrane potential, mitochondrial permeability transition pore (mPTP), mitochondrial ultrastructure and ATP content. Oxidative stress-related indicators reactive oxygen species, superoxide dismutase and malondialdehyde were also assessed. To verify the relevance between oxidative stress and necroptosis together with apoptosis, RIPK1 inhibitor necrostatin-1(Nec-1), mPTP inhibitor cyclosporine A (CsA), antioxidants and small interfering RNA technology were utilized. The results established that compression elicited a time-dependent mitochondrial dysfunction and elevated oxidative stress. Nec-1 and CsA restored mitochondrial function and reduced oxidative stress, which corresponded to decreased necroptosis and apoptosis. CsA down-regulated mitochondrial cyclophilin D expression, but had little effects on RIPK1 expression and pRIPK1 activation. Additionally, we found that Nec-1 largely blocked apoptosis; whereas, the apoptosis inhibitor Z-VAD-FMK increased RIPK1 expression and pRIPK1 activation, and coordinated regulation of necroptosis and apoptosis enabled NP cells survival more efficiently. In contrast to Nec-1, SiRIPK1 exacerbated mitochondrial dysfunction and oxidative stress. In summary, RIPK1-mediated mitochondrial dysfunction and oxidative stress play a crucial role in NP cells necroptosis and apoptosis during compression injury. The synergistic regulation of necroptosis and apoptosis may exert more beneficial effects on NP cells survival, and ultimately delaying or even retarding intervertebral disc degeneration.

A complete mitochondrial genome of wheat (Triticum aestivum cv. Chinese Yumai), and fast evolving mitochondrial genes in higher plants.

PubMed

Cui, Peng; Liu, Huitao; Lin, Qiang; Ding, Feng; Zhuo, Guoyin; Hu, Songnian; Liu, Dongcheng; Yang, Wenlong; Zhan, Kehui; Zhang, Aimin; Yu, Jun

2009-12-01

Plant mitochondrial genomes, encoding necessary proteins involved in the system of energy production, play an important role in the development and reproduction of the plant. They occupy a specific evolutionary pattern relative to their nuclear counterparts. Here, we determined the winter wheat (Triticum aestivum cv. Chinese Yumai) mitochondrial genome in a length of 452 and 526 bp by shotgun sequencing its BAC library. It contains 202 genes, including 35 known protein-coding genes, three rRNA and 17 tRNA genes, as well as 149 open reading frames (ORFs; greater than 300 bp in length). The sequence is almost identical to the previously reported sequence of the spring wheat (T. aestivum cv. Chinese Spring); we only identified seven SNPs (three transitions and four transversions) and 10 indels (insertions and deletions) between the two independently acquired sequences, and all variations were found in non-coding regions. This result confirmed the accuracy of the previously reported mitochondrial sequence of the Chinese Spring wheat. The nucleotide frequency and codon usage of wheat are common among the lineage of higher plant with a high AT-content of 58%. Molecular evolutionary analysis demonstrated that plant mitochondrial genomes evolved at different rates, which may correlate with substantial variations in metabolic rate and generation time among plant lineages. In addition, through the estimation of the ratio of non-synonymous to synonymous substitution rates between orthologous mitochondrion-encoded genes of higher plants, we found an accelerated evolutionary rate that seems to be the result of relaxed selection.

Activation of sirtuin 1/3 improves vascular hyporeactivity in severe hemorrhagic shock by alleviation of mitochondrial damage

PubMed Central

Li, Pengyun; Meng, Xianzhong; Bian, Huining; Burns, Nana; Zhao, Ke-seng; Song, Rui

2015-01-01

Vascular hyporeactivity is one of the major causes responsible for refractory hypotension and associated mortality in severe hemorrhagic shock. Mitochondrial permeability transition (mPT) pore opening in arteriolar smooth muscle cells (ASMCs) is involved in the pathogenesis of vascular hyporeactivity. However, the molecular mechanism underlying mitochondrial injury in ASMCs during hemorrhagic shock is not well understood. Here we produced an in vivo model of severe hemorrhagic shock in adult Wistar rats. We found that sirtuin (SIRT)1/3 protein levels and deacetylase activities were decreased in ASMCs following severe shock. Immunofluorescence staining confirmed reduced levels of SIRT1 in the nucleus and SIRT3 in the mitochondria, respectively. Acetylation of cyclophilin D (CyPD), a component of mPT pore, was increased. SIRT1 activators suppressed mPT pore opening and ameliorated mitochondrial injury in ASMCs after severe shock. Furthermore, administration of SIRT1 activators improved vasoreactivity in rats under severe shock. Our data suggest that epigenetic mechanisms, namely histone post-translational modifications, are involved in regulation of mPT by SIRT1/SIRT3- mediated deacetylation of CyPD. SIRT1/3 is a promising therapeutic target for the treatment of severe hemorrhagic shock. PMID:26473372

Bmi1 overexpression in the cerebellar granule cell lineage of mice affects cell proliferation and survival without initiating medulloblastoma formation

PubMed Central

Behesti, Hourinaz; Bhagat, Heeta; Dubuc, Adrian M.; Taylor, Michael D.; Marino, Silvia

2013-01-01

SUMMARY BMI1 is a potent inducer of neural stem cell self-renewal and neural progenitor cell proliferation during development and in adult tissue homeostasis. It is overexpressed in numerous human cancers – including medulloblastomas, in which its functional role is unclear. We generated transgenic mouse lines with targeted overexpression of Bmi1 in the cerebellar granule cell lineage, a cell type that has been shown to act as a cell of origin for medulloblastomas. Overexpression of Bmi1 in granule cell progenitors (GCPs) led to a decrease in cerebellar size due to decreased GCP proliferation and repression of the expression of cyclin genes, whereas Bmi1 overexpression in postmitotic granule cells improved cell survival in response to stress by altering the expression of genes in the mitochondrial cell death pathway and of Myc and Lef-1. Although no medulloblastomas developed in ageing cohorts of transgenic mice, crosses with Trp53−/− mice resulted in a low incidence of medulloblastoma formation. Furthermore, analysis of a large collection of primary human medulloblastomas revealed that tumours with a BMI1high TP53low molecular profile are significantly enriched in Group 4 human medulloblastomas. Our data suggest that different levels and timing of Bmi1 overexpression yield distinct cellular outcomes within the same cellular lineage. Importantly, Bmi1 overexpression at the GCP stage does not induce tumour formation, suggesting that BMI1 overexpression in GCP-derived human medulloblastomas probably occurs during later stages of oncogenesis and might serve to enhance tumour cell survival. PMID:23065639

Mitochondrial gene rearrangements confirm the parallel evolution of the crab-like form.

PubMed Central

Morrison, C L; Harvey, A W; Lavery, S; Tieu, K; Huang, Y; Cunningham, C W

2002-01-01

The repeated appearance of strikingly similar crab-like forms in independent decapod crustacean lineages represents a remarkable case of parallel evolution. Uncertainty surrounding the phylogenetic relationships among crab-like lineages has hampered evolutionary studies. As is often the case, aligned DNA sequences by themselves were unable to fully resolve these relationships. Four nested mitochondrial gene rearrangements--including one of the few reported movements of an arthropod protein-coding gene--are congruent with the DNA phylogeny and help to resolve a crucial node. A phylogenetic analysis of DNA sequences, and gene rearrangements, supported five independent origins of the crab-like form, and suggests that the evolution of the crab-like form may be irreversible. This result supports the utility of mitochondrial gene rearrangements in phylogenetic reconstruction. PMID:11886621

Snf1-related kinase improves cardiac mitochondrial efficiency and decreases mitochondrial uncoupling

PubMed Central

Rines, Amy K.; Chang, Hsiang-Chun; Wu, Rongxue; Sato, Tatsuya; Khechaduri, Arineh; Kouzu, Hidemichi; Shapiro, Jason; Shang, Meng; Burke, Michael A.; Abdelwahid, Eltyeb; Jiang, Xinghang; Chen, Chunlei; Rawlings, Tenley A.; Lopaschuk, Gary D.; Schumacker, Paul T.; Abel, E. Dale; Ardehali, Hossein

2017-01-01

Ischaemic heart disease limits oxygen and metabolic substrate availability to the heart, resulting in tissue death. Here, we demonstrate that the AMP-activated protein kinase (AMPK)-related protein Snf1-related kinase (SNRK) decreases cardiac metabolic substrate usage and mitochondrial uncoupling, and protects against ischaemia/reperfusion. Hearts from transgenic mice overexpressing SNRK have decreased glucose and palmitate metabolism and oxygen consumption, but maintained power and function. They also exhibit decreased uncoupling protein 3 (UCP3) and mitochondrial uncoupling. Conversely, Snrk knockout mouse hearts have increased glucose and palmitate oxidation and UCP3. SNRK knockdown in cardiac cells decreases mitochondrial efficiency, which is abolished with UCP3 knockdown. We show that Tribbles homologue 3 (Trib3) binds to SNRK, and downregulates UCP3 through PPARα. Finally, SNRK is increased in cardiomyopathy patients, and SNRK reduces infarct size after ischaemia/reperfusion. SNRK also decreases cardiac cell death in a UCP3-dependent manner. Our results suggest that SNRK improves cardiac mitochondrial efficiency and ischaemic protection. PMID:28117339

The mitochondrial DNA makeup of Romanians: A forensic mtDNA control region database and phylogenetic characterization.

PubMed

Turchi, Chiara; Stanciu, Florin; Paselli, Giorgia; Buscemi, Loredana; Parson, Walther; Tagliabracci, Adriano

2016-09-01

To evaluate the pattern of Romanian population from a mitochondrial perspective and to establish an appropriate mtDNA forensic database, we generated a high-quality mtDNA control region dataset from 407 Romanian subjects belonging to four major historical regions: Moldavia, Transylvania, Wallachia and Dobruja. The entire control region (CR) was analyzed by Sanger-type sequencing assays and the resulting 306 different haplotypes were classified into haplogroups according to the most updated mtDNA phylogeny. The Romanian gene pool is mainly composed of West Eurasian lineages H (31.7%), U (12.8%), J (10.8%), R (10.1%), T (9.1%), N (8.1%), HV (5.4%),K (3.7%), HV0 (4.2%), with exceptions of East Asian haplogroup M (3.4%) and African haplogroup L (0.7%). The pattern of mtDNA variation observed in this study indicates that the mitochondrial DNA pool is geographically homogeneous across Romania and that the haplogroup composition reveals signals of admixture of populations of different origin. The PCA scatterplot supported this scenario, with Romania located in southeastern Europe area, close to Bulgaria and Hungary, and as a borderland with respect to east Mediterranean and other eastern European countries. High haplotype diversity (0.993) and nucleotide diversity indices (0.00838±0.00426), together with low random match probability (0.0087) suggest the usefulness of this control region dataset as a forensic database in routine forensic mtDNA analysis and in the investigation of maternal genetic lineages in the Romanian population. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle.

PubMed

Pecorella, Shelly R H; Potter, Jennifer V F; Cherry, Anne D; Peacher, Dionne F; Welty-Wolf, Karen E; Moon, Richard E; Piantadosi, Claude A; Suliman, Hagir B

2015-10-15

The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity. Copyright © 2015 the American Physiological Society.

Ionizing radiation induces mitochondrial reactive oxygen species production accompanied by upregulation of mitochondrial electron transport chain function and mitochondrial content under control of the cell cycle checkpoint.

PubMed

Yamamori, Tohru; Yasui, Hironobu; Yamazumi, Masayuki; Wada, Yusuke; Nakamura, Yoshinari; Nakamura, Hideo; Inanami, Osamu

2012-07-15

Whereas ionizing radiation (Ir) instantaneously causes the formation of water radiolysis products that contain some reactive oxygen species (ROS), ROS are also suggested to be released from biological sources in irradiated cells. It is now becoming clear that these ROS generated secondarily after Ir have a variety of biological roles. Although mitochondria are assumed to be responsible for this Ir-induced ROS production, it remains to be elucidated how Ir triggers it. Therefore, we conducted this study to decipher the mechanism of Ir-induced mitochondrial ROS production. In human lung carcinoma A549 cells, Ir (10 Gy of X-rays) induced a time-dependent increase in the mitochondrial ROS level. Ir also increased mitochondrial membrane potential, mitochondrial respiration, and mitochondrial ATP production, suggesting upregulation of the mitochondrial electron transport chain (ETC) function after Ir. Although we found that Ir slightly enhanced mitochondrial ETC complex II activity, the complex II inhibitor 3-nitropropionic acid failed to reduce Ir-induced mitochondrial ROS production. Meanwhile, we observed that the mitochondrial mass and mitochondrial DNA level were upregulated after Ir, indicating that Ir increased the mitochondrial content of the cell. Because irradiated cells are known to undergo cell cycle arrest under control of the checkpoint mechanisms, we examined the relationships between cell cycle and mitochondrial content and cellular oxidative stress level. We found that the cells in the G2/M phase had a higher mitochondrial content and cellular oxidative stress level than cells in the G1 or S phase, regardless of whether the cells were irradiated. We also found that Ir-induced accumulation of the cells in the G2/M phase led to an increase in cells with a high mitochondrial content and cellular oxidative stress level. This suggested that Ir upregulated mitochondrial ETC function and mitochondrial content, resulting in mitochondrial ROS production, and that

Mitochondrial Control by DRP1 in Brain Tumor Initiating Cells

PubMed Central

Xie, Qi; Wu, Qiulian; Horbinski, Craig M.; Flavahan, William A.; Yang, Kailin; Zhou, Wenchao; Dombrowski, Stephen M.; Huang, Zhi; Fang, Xiaoguang; Shi, Yu; Ferguson, Ashley N.; Kashatus, David F.; Bao, Shideng; Rich, Jeremy N.

2015-01-01

Brain tumor initiating cells (BTICs) coopt the neuronal high affinity GLUT3 glucose transporter to withstand metabolic stress. Here, we investigated another mechanism critical to brain metabolism, mitochondrial morphology. BTICs displayed mitochondrial fragmentation relative to non-BTICs, suggesting that BTICs have increased mitochondrial fission. The essential mediator of mitochondrial fission, dynamin-related protein 1 (DRP1), was activated in BTICs and inhibited in non-BTICs. Targeting DRP1 using RNA interference or pharmacologic inhibition induced BTIC apoptosis and inhibited tumor growth. Downstream, DRP1 activity regulated the essential metabolic stress sensor, AMP-activated protein kinase (AMPK), and AMPK targeting rescued the effects of DRP1 disruption. Cyclin-dependent kinase 5 (CDK5) phosphorylated DRP1 to increase its activity in BTICs, whereas Ca2+–calmodulin-dependent protein kinase 2 (CAMK2) inhibited DRP1 in non-BTICs, suggesting tumor cell differentiation induces a regulatory switch in mitochondrial morphology. DRP1 activation correlates with poor prognosis in glioblastoma, suggesting mitochondrial dynamics may represent a therapeutic target for BTICs. PMID:25730670

Drosophila mitochondrial transcription factor B1 modulates mitochondrial translation but not transcription or DNA copy number in Schneider cells.

PubMed

Matsushima, Yuichi; Adán, Cristina; Garesse, Rafael; Kaguni, Laurie S

2005-04-29

We report the cloning and molecular analysis of Drosophila mitochondrial transcription factor (d-mtTF) B1. An RNA interference (RNAi) construct was designed that reduces expression of d-mtTFB1 to 5% of its normal level in Schneider cells. In striking contrast with our previous study on d-mtTFB2, we found that RNAi knock-down of d-mtTFB1 does not change the abundance of specific mitochondrial RNA transcripts, nor does it affect the copy number of mitochondrial DNA. In a corollary manner, overexpression of d-mtTFB1 did not increase either the abundance of mitochondrial RNA transcripts or mitochondrial DNA copy number. Our data suggest that, unlike d-mtTFB2, d-mtTFB1 does not have a critical role in either transcription or regulation of the copy number of mitochondrial DNA. Instead, because we found that RNAi knockdown of d-mtTFB1 reduces mitochondrial protein synthesis, we propose that it serves its primary role in modulating translation. Our work represents the first study to document the role of mtTFB1 in vivo and establishes clearly functional differences between mtTFB1 and mtTFB2.

Rheb and mammalian target of rapamycin in mitochondrial homoeostasis

PubMed Central

Groenewoud, Marlous J.; Zwartkruis, Fried J. T.

2013-01-01

Mitochondrial dysfunction has been associated with various diseases, such as cancer, myopathies, neurodegeneration and obesity. Mitochondrial homoeostasis is achieved by mechanisms that adapt the number of mitochondria to that required for energy production and for the supply of metabolic intermediates necessary to sustain cell growth. Simultaneously, mitochondrial quality control mechanisms are in place to remove malfunctioning mitochondria. In the cytoplasm, the protein complex mTORC1 couples growth-promoting signals with anabolic processes, in which mitochondria play an essential role. Here, we review the involvement of mTORC1 and Rheb in mitochondrial homoeostasis. The regulatory processes downstream of mTORC1 affect the glycolytic flux and the rate of mitophagy, and include regulation of the transcription factors HIF1α and YY1/PGC-1α. We also discuss how mitochondrial function feeds back on mTORC1 via reactive oxygen species signalling to adapt metabolic processes, and highlight how mTORC1 signalling is integrated with the unfolded protein response in mitochondria, which in Caenorhabditis elegans is mediated via transcription factors such as DVE-1/UBL-5 and ATFS-1. PMID:24352740

Hemosporidian parasites in forest birds from Venezuela: genetic lineage analyses.

PubMed

Mijares, Alfredo; Rosales, Romel; Silva-Iturriza, Adriana

2012-09-01

Avian hemosporidian parasites of the genera Haemoproteus, Plasmodium, and Leucocytozoon are transmitted by different dipteran vectors. In the present work, we looked for the presence of these parasites in 47 birds from 12 families, which were sampled in the migratory corridor Paso de Portachuelo, located at the Henri Pittier National Park, Venezuela. The presence of the parasites was evidenced by amplification of a region of 471 bp of their cytochrome b gene. This region of the marker presents enough polymorphism to identify most of the mitochondrial lineages. Therefore, the obtained amplicons were sequenced, not only to identify the genus of the parasites sampled, but also to analyze their genetic diversity in the study area. The overall parasite prevalence was low (11%). We reported, for the first time, Plasmodium in birds of the species Formicarius analis and Chamaeza campanisona (Formicariidae) and Haemoproteus in Geotrygon linearis (Columbidae). A phylogenetic tree was generated using the Haemoproteus, Plasmodium, and Leucocytozoon sequences obtained in this study, together with representative sequences from previous studies. The highest genetic diversities between the two Haemoproteus lineages (11.70%) and among the three Plasmodium lineages (7.86%) found in this study are also similar to those found when lineages reported in the literature were used. These results indicate that in the migratory corridor Paso de Portachuleo, representative parasite lineages are found, making this location an attractive location for future studies.

Increased mitochondrial-encoded gene transcription in immortal DF-1 cells.

PubMed

Kim, H; You, S; Kim, I J; Farris, J; Foster, L K; Foster, D N

2001-05-01

We have established, in continuous cell culture, a spontaneously immortalized chicken embryo fibroblast (CEF) cell line (DF-1) as well as several other immortal CEF cell lines. The immortal DF-1 cells divided more rapidly than primary and other immortal CEF cells. To identify the genes involved in rapidly dividing DF-1 cells, we have used differential display RT-PCR. Of the numerous genes analyzed, three mitochondrial-encoded genes (ATPase 8/6, 16S rRNA, and cytochrome b) were shown to express at higher levels in DF-1 cells compared to primary and other immortal CEF cells. The inhibition of mitochondrial translation by treatment with chloramphenicol markedly decreased ATP production and cell proliferation in DF-1 cells, while not affecting growth in either primary or other immortal CEF cells. This result suggests a correlation between rapid cell proliferation and the increased mitochondrial respiratory functions. We also determined that the increased transcription of mitochondrial-encoded genes in DF-1 cells is due to increased de novo transcript synthesis as shown by mitochondrial run-on assays, and not the result of either increased mitochondrial biogenesis or mitochondrial transcript half-lives. Together, the present studies suggest that the transcriptional activation of mitochondrial-encoded genes and the elevated respiratory function should be one of the characteristics of rapidly dividing immortal cells. Copyright 2001 Academic Press.

mRNA localization to the mitochondrial surface allows the efficient translocation inside the organelle of a nuclear recoded ATP6 protein

PubMed Central

Kaltimbacher, Valérie; Bonnet, Crystel; Lecoeuvre, Gaëlle; Forster, Valérie; Sahel, José-Alain; Corral-Debrinski, Marisol

2006-01-01

As previously established in yeast, two sequences within mRNAs are responsible for their specific localization to the mitochondrial surface—the region coding for the mitochondrial targeting sequence and the 3′UTR. This phenomenon is conserved in human cells. Therefore, we decided to use mRNA localization as a tool to address to mitochondria, a protein that is not normally imported. For this purpose, we associated a nuclear recoded ATP6 gene with the mitochondrial targeting sequence and the 3′UTR of the nuclear SOD2 gene, which mRNA exclusively localizes to the mitochondrial surface in HeLa cells. The ATP6 gene is naturally located into the organelle and encodes a highly hydrophobic protein of the respiratory chain complex V. In this study, we demonstrated that hybrid ATP6 mRNAs, as the endogenous SOD2 mRNA, localize to the mitochondrial surface in human cells. Remarkably, fusion proteins localize to mitochondria in vivo. Indeed, ATP6 precursors synthesized in the cytoplasm were imported into mitochondria in a highly efficient way, especially when both the MTS and the 3′UTR of the SOD2 gene were associated with the re-engineered ATP6 gene. Hence, these data indicate that mRNA targeting to the mitochondrial surface represents an attractive strategy for allowing the mitochondrial import of proteins originally encoded by the mitochondrial genome without any amino acid change in the protein that could interfere with its biologic activity. PMID:16751614

NDE1 and GSK3β Associate with TRAK1 and Regulate Axonal Mitochondrial Motility: Identification of Cyclic AMP as a Novel Modulator of Axonal Mitochondrial Trafficking.

PubMed

Ogawa, Fumiaki; Murphy, Laura C; Malavasi, Elise L V; O'Sullivan, Shane T; Torrance, Helen S; Porteous, David J; Millar, J Kirsty

2016-05-18

Mitochondria are essential for neuronal function, providing the energy required to power neurotransmission, and fulfilling many important additional roles. In neurons, mitochondria must be efficiently transported to sites, including synapses, where their functions are required. Neurons, with their highly elongated morphology, are consequently extremely sensitive to defective mitochondrial trafficking which can lead to neuronal ill-health/death. We recently demonstrated that DISC1 associates with mitochondrial trafficking complexes where it associates with the core kinesin and dynein adaptor molecule TRAK1. We now show that the DISC1 interactors NDE1 and GSK3β also associate robustly with TRAK1 and demonstrate that NDE1 promotes retrograde axonal mitochondrial movement. GSK3β is known to modulate axonal mitochondrial motility, although reports of its actual effect are conflicting. We show that, in our system, GSK3β promotes anterograde mitochondrial transport. Finally, we investigated the influence of cAMP elevation upon mitochondrial motility, and found a striking increase in mitochondrial motility and retrograde movement. DISC1, NDE1, and GSK3β are implicated as risk factors for major mental illness. Our demonstration that they function together within mitochondrial trafficking complexes suggests that defective mitochondrial transport may be a contributory disease mechanism in some cases of psychiatric disorder.

Synthetic Ubiquinones Specifically Bind to Mitochondrial Voltage-Dependent Anion Channel 1 (VDAC1) in Saccharomyces cerevisiae Mitochondria.

PubMed

Murai, Masatoshi; Okuda, Ayaka; Yamamoto, Takenori; Shinohara, Yasuo; Miyoshi, Hideto

2017-01-31

The role of the voltage-dependent anion channel (VDAC) as a metabolic gate of the mitochondrial outer membrane has been firmly established; however, its involvement in the regulation of mitochondrial permeability transition (PT) remains extremely controversial. Although some low-molecular-weight chemicals have been proposed to modulate the regulatory role of VDAC in the induction of PT, direct binding between these chemicals and VDAC has not yet been demonstrated. In the present study, we investigated whether the ubiquinone molecule directly binds to VDAC in Saccharomyces cerevisiae mitochondria through a photoaffinity labeling technique using two photoreactive ubiquinones (PUQ-1 and PUQ-2). The results of the labeling experiments demonstrated that PUQ-1 and PUQ-2 specifically bind to VDAC1 and that the labeled position is located in the C-terminal region Phe221-Lys234, connecting the 15th and 16th β-strand sheets. Mutations introduced in this region (R224A, Y225A, D228A, and Y225A/D228A) hardly affected the binding affinity of PUQ-1. PUQ-1 and PUQ-2 both significantly suppressed the Ca 2+ -induced mitochondrial PT (monitored by mitochondrial swelling) at the one digit μM level. Thus, the results of the present study provided, for the first time to our knowledge, direct evidence indicating that the ubiquinone molecule specifically binds to VDAC1 through its quinone-head ring.

Mitochondrial dysfunction-associated OPA1 cleavage contributes to muscle degeneration: preventative effect of hydroxytyrosol acetate.

PubMed

Wang, X; Li, H; Zheng, A; Yang, L; Liu, J; Chen, C; Tang, Y; Zou, X; Li, Y; Long, J; Liu, J; Zhang, Y; Feng, Z

2014-11-13

Mitochondrial dysfunction contributes to the development of muscle disorders, including muscle wasting, muscle atrophy and degeneration. Despite the knowledge that oxidative stress closely interacts with mitochondrial dysfunction, the detailed mechanisms remain obscure. In this study, tert-butylhydroperoxide (t-BHP) was used to induce oxidative stress on differentiated C2C12 myotubes. t-BHP induced significant mitochondrial dysfunction in a time-dependent manner, accompanied by decreased myosin heavy chain (MyHC) expression at both the mRNA and protein levels. Consistently, endogenous reactive oxygen species (ROS) overproduction triggered by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), a mitochondrial oxidative phosphorylation inhibitor, was accompanied by decreased membrane potential and decreased MyHC protein content. However, the free radical scavenger N-acetyl-L-cysteine (NAC) efficiently reduced the ROS level and restored MyHC content, suggesting a close association between ROS and MyHC expression. Meanwhile, we found that both t-BHP and FCCP promoted the cleavage of optic atrophy 1 (OPA1) from the long form into short form during the early stages. In addition, the ATPase family gene 3-like 2, a mitochondrial inner membrane protease, was also markedly increased. Moreover, OPA1 knockdown in myotubes was accompanied by decreased MyHC content, whereas NAC failed to prevent FCCP-induced MyHC decrease with OPA1 knockdown, suggesting that ROS might affect MyHC content by modulating OPA1 cleavage. In addition, hydroxytyrosol acetate (HT-AC), an important compound in virgin olive oil, could significantly prevent t-BHP-induced mitochondrial membrane potential and cell viability loss in myotubes. Specifically, HT-AC inhibited t-BHP-induced OPA1 cleavage and mitochondrial morphology changes, accompanied by improvement on mitochondrial oxygen consumption capacity, ATP productive potential and activities of mitochondrial complex I, II and V. Moreover, both

Integrated genomic analysis of mitochondrial RNA processing in human cancers.

PubMed

Idaghdour, Youssef; Hodgkinson, Alan

2017-04-18

The mitochondrial genome is transcribed as continuous polycistrons of RNA containing multiple genes. As a consequence, post-transcriptional events are critical for the regulation of gene expression and therefore all aspects of mitochondrial function. One particularly important process is the m 1 A/m 1 G RNA methylation of the ninth position of different mitochondrial tRNAs, which allows efficient processing of mitochondrial mRNAs and protein translation, and de-regulation of genes involved in these processes has been associated with altered mitochondrial function. Although mitochondria play a key role in cancer, the status of mitochondrial RNA processing in tumorigenesis is unknown. We measure and assess mitochondrial RNA processing using integrated genomic analysis of RNA sequencing and genotyping data from 1226 samples across 12 different cancer types. We focus on the levels of m 1 A and m 1 G RNA methylation in mitochondrial tRNAs in normal and tumor samples and use supervised and unsupervised statistical analysis to compare the levels of these modifications to patient whole genome genotypes, nuclear gene expression, and survival outcomes. We find significant changes to m 1 A and m 1 G RNA methylation levels in mitochondrial tRNAs in tumor tissues across all cancers. Pathways of RNA processing are strongly associated with methylation levels in normal tissues (P = 3.27 × 10 -31 ), yet these associations are lost in tumors. Furthermore, we report 18 gene-by-disease-state interactions where altered RNA methylation levels occur under cancer status conditional on genotype, implicating genes associated with mitochondrial function or cancer (e.g., CACNA2D2, LMO2, and FLT3) and suggesting that nuclear genetic variation can potentially modulate an individual's ability to maintain unaltered rates of mitochondrial RNA processing under cancer status. Finally, we report a significant association between the magnitude of methylation level changes in tumors and

Ionizing radiation accelerates Drp1-dependent mitochondrial fission, which involves delayed mitochondrial reactive oxygen species production in normal human fibroblast-like cells

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

Kobashigawa, Shinko, E-mail: kobashin@nagasaki-u.ac.jp; Suzuki, Keiji; Yamashita, Shunichi

2011-11-04

Highlights: Black-Right-Pointing-Pointer We report first time that ionizing radiation induces mitochondrial dynamic changes. Black-Right-Pointing-Pointer Radiation-induced mitochondrial fission was caused by Drp1 localization. Black-Right-Pointing-Pointer We found that radiation causes delayed ROS from mitochondria. Black-Right-Pointing-Pointer Down regulation of Drp1 rescued mitochondrial dysfunction after radiation exposure. -- Abstract: Ionizing radiation is known to increase intracellular level of reactive oxygen species (ROS) through mitochondrial dysfunction. Although it has been as a basis of radiation-induced genetic instability, the mechanism involving mitochondrial dysfunction remains unclear. Here we studied the dynamics of mitochondrial structure in normal human fibroblast like cells exposed to ionizing radiation. Delayed mitochondrial O{submore » 2}{sup {center_dot}-} production was peaked 3 days after irradiation, which was coupled with accelerated mitochondrial fission. We found that radiation exposure accumulated dynamin-related protein 1 (Drp1) to mitochondria. Knocking down of Drp1 expression prevented radiation induced acceleration of mitochondrial fission. Furthermore, knockdown of Drp1 significantly suppressed delayed production of mitochondrial O{sub 2}{sup {center_dot}-}. Since the loss of mitochondrial membrane potential, which was induced by radiation was prevented in cells knocking down of Drp1 expression, indicating that the excessive mitochondrial fission was involved in delayed mitochondrial dysfunction after irradiation.« less

Mitochondrial phylogeny of grey mullets (Acanthopterygii: Mugilidae) suggests high proportion of cryptic species.

PubMed

Durand, Jean-Dominique; Borsa, Philippe

2015-04-01

The low level of morphometric variability and the poor phylogenetic information borne by the morpho-anatomical characters used thus far in the systematics of grey mullets (Mugilidae) emphasize the utility of molecular systematics in this family. A recent mitochondrial phylogeny of grey mullets has uncovered multiple deep lineages within several species, flagging putative cryptic species. Here, we considered that several of the deeply divergent lineages represent separate species based on either the tree topology, independent data from nuclear markers, geographic distributions, or a combination of the foregoing. By analogy with these well-documented cases, we considered other deep lineages in seven genera we focused on to represent putative cryptic species. Up to two cryptic species were thus potentially detected in the genus Chelon, three in Crenimugil (including two within the single Crenimugil seheli), two in Dajaus, one in Ellochelon, 16 in Mugil (including 13 within the single M. cephalus), two in Osteomugil, and 10 in Planiliza. Wherever possible, we kept the current species epithets to designate those lineages that unambiguously correspond to the type material, based on type locality, and we assigned arbitrary letters (sp. A, B, etc.) to the other lineages. We present a molecular diagnosis for 24 of the species analysed in this work, as well as for 25 putative cryptic species. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Mitochondrial remodeling following fission inhibition by 15d-PGJ2 involves molecular changes in mitochondrial fusion protein OPA1

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

Kar, Rekha; Department of Biochemistry, UT Health Science Center at San Antonio, San Antonio, TX 78229; Mishra, Nandita

2010-09-03

Research highlights: {yields} Chemical inhibition of fission protein Drp1 leads to mitochondrial fusion. {yields} Increased fusion stimulates molecular changes in mitochondrial fusion protein OPA1. {yields} Proteolysis of larger isoforms, new synthesis and ubiquitination of OPA1 occur. {yields} Loss of mitochondrial tubular rigidity and disorganization of cristae. {yields} Generation of large swollen dysfunctional mitochondria. -- Abstract: We showed earlier that 15 deoxy {Delta}{sup 12,14} prostaglandin J2 (15d-PGJ2) inactivates Drp1 and induces mitochondrial fusion . However, prolonged incubation of cells with 15d-PGJ2 resulted in remodeling of fused mitochondria into large swollen mitochondria with irregular cristae structure. While initial fusion of mitochondria bymore » 15d-PGJ2 required the presence of both outer (Mfn1 and Mfn2) and inner (OPA1) mitochondrial membrane fusion proteins, later mitochondrial changes involved increased degradation of the fusion protein OPA1 and ubiquitination of newly synthesized OPA1 along with decreased expression of Mfn1 and Mfn2, which likely contributed to the loss of tubular rigidity, disorganization of cristae, and formation of large swollen degenerated dysfunctional mitochondria. Similar to inhibition of Drp1 by 15d-PGJ2, decreased expression of fission protein Drp1 by siRNA also resulted in the loss of fusion proteins. Prevention of 15d-PGJ2 induced mitochondrial elongation by thiol antioxidants prevented not only loss of OPA1 isoforms but also its ubiquitination. These findings provide novel insights into unforeseen complexity of molecular events that modulate mitochondrial plasticity.« less

Mosaic Origins of a Complex Chimeric Mitochondrial Gene in Silene vulgaris

PubMed Central

Storchova, Helena; Müller, Karel; Lau, Steffen; Olson, Matthew S.

2012-01-01

Chimeric genes are significant sources of evolutionary innovation that are normally created when portions of two or more protein coding regions fuse to form a new open reading frame. In plant mitochondria astonishingly high numbers of different novel chimeric genes have been reported, where they are generated through processes of rearrangement and recombination. Nonetheless, because most studies do not find or report nucleotide variation within the same chimeric gene, evolution after the origination of these chimeric genes remains unstudied. Here we identify two alleles of a complex chimera in Silene vulgaris that are divergent in nucleotide sequence, genomic position relative to other mitochondrial genes, and expression patterns. Structural patterns suggest a history partially influenced by gene conversion between the chimeric gene and functional copies of subunit 1 of the mitochondrial ATP synthase gene (atp1). We identified small repeat structures within the chimeras that are likely recombination sites allowing generation of the chimera. These results establish the potential for chimeric gene divergence in different plant mitochondrial lineages within the same species. This result contrasts with the absence of diversity within mitochondrial chimeras found in crop species. PMID:22383961

A novel mutation MT-COIII m.9267G>C and MT-COI m.5913G>A mutation in mitochondrial genes in a Tunisian family with maternally inherited diabetes and deafness (MIDD) associated with sever nephropathy

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

Tabebi, Mouna, E-mail: mouna.biologiste@yahoo.com; Mkaouar-Rebai, Emna; Mnif, Mouna

Mitochondrial diabetes (MD) is a heterogeneous disorder characterized by a chronic hyperglycemia, maternal transmission and its association with a bilateral hearing impairment. Several studies reported mutations in mitochondrial genes as potentially pathogenic for diabetes, since mitochondrial oxidative phosphorylation plays an important role in glucose-stimulated insulin secretion from beta cells. In the present report, we studied a Tunisian family with mitochondrial diabetes (MD) and deafness associated with nephropathy. The mutational analysis screening revealed the presence of a novel heteroplasmic mutation m.9276G>C in the mitochondrial COIII gene, detected in mtDNA extracted from leukocytes of a mother and her two daughters indicating thatmore » this mutation is maternally transmitted and suggest its implication in the observed phenotype. Bioinformatic tools showed that m.9267G>C mutation (p.A21P) is « deleterious » and it can modify the function and the stability of the MT-COIII protein by affecting the assembly of mitochondrial COX subunits and the translocation of protons then reducing the activity of the respective OXPHOS complexes of ATP synthesis. The nonsynonymous mutation (p.A21P) has not been reported before, it is the first mutation described in the COXIII gene which is related to insulin dependent mitochondrial diabetes and deafness and could be specific to the Tunisian population. The m.9267G>C mutation was present with a nonsynonymous inherited mitochondrial homoplasmic variation MT-COI m.5913 G>A (D4N) responsible of high blood pressure, a clinical feature detected in all explored patients. - Highlights: • MT-COX3 m.9267G>C (p.A21P), heteroplasmic substitution, is not reported in any database. • m.9267G>C can be responsible of the MIDD associated with nephropaty. • This substitution can modify the function and the stability of the MT-CO3 protein. • This substitution can modify MT-CO3 structure (2D and 3D). • MT-COX3 m.9267G>C is

Ecomorph or Endangered Coral? DNA and Microstructure Reveal Hawaiian Species Complexes: Montipora dilatata/flabellata/turgescens & M. patula/verrilli

PubMed Central

Forsman, Zac H.; Concepcion, Gregory T.; Haverkort, Roxanne D.; Shaw, Ross W.; Maragos, James E.; Toonen, Robert J.

2010-01-01

M. dilatata, M. flabellata, and M. patula and 80 other scleractinian corals were petitioned to be listed under the US Endangered Species Act (ESA), which would have major conservation implications. One of the difficulties with this evaluation is that reproductive boundaries between morphologically defined coral species are often permeable, and morphology can be wildly variable. We examined genetic and morphological variation in Hawaiian Montipora with a suite of molecular markers (mitochondrial: COI, CR, Cyt-B, 16S, ATP6; nuclear: ATPsβ, ITS) and microscopic skeletal measurements. Mitochondrial markers and the ITS region revealed four distinct clades: I) M. patula/M. verrilli, II) M. cf. incrassata, III) M. capitata, IV) M. dilatata/M. flabellata/M. cf. turgescens. These clades are likely to occur outside of Hawai'i according to mitochondrial control region haplotypes from previous studies. The ATPsβ intron data showed a pattern often interpreted as resulting from hybridization and introgression; however, incomplete lineage sorting may be more likely since the multicopy nuclear ITS region was consistent with the mitochondrial data. Furthermore, principal components analysis (PCA) of skeletal microstructure was concordant with the mitochondrial clades, while nominal taxa overlapped. The size and shape of verrucae or papillae contributed most to identifying groups, while colony-level morphology was highly variable. It is not yet clear if these species complexes represent population-level variation or incipient speciation (CA<1MYA), two alternatives that have very different conservation implications. This study highlights the difficulty in understanding the scale of genetic and morphological variation that corresponds to species as opposed to population-level variation, information that is essential for conservation and for understanding coral biodiversity. PMID:21151995

Ecomorph or endangered coral? DNA and microstructure reveal hawaiian species complexes: Montipora dilatata/flabellata/turgescens & M. patula/verrilli.

PubMed

Forsman, Zac H; Concepcion, Gregory T; Haverkort, Roxanne D; Shaw, Ross W; Maragos, James E; Toonen, Robert J

2010-12-02

M. dilatata, M. flabellata, and M. patula and 80 other scleractinian corals were petitioned to be listed under the US Endangered Species Act (ESA), which would have major conservation implications. One of the difficulties with this evaluation is that reproductive boundaries between morphologically defined coral species are often permeable, and morphology can be wildly variable. We examined genetic and morphological variation in Hawaiian Montipora with a suite of molecular markers (mitochondrial: COI, CR, Cyt-B, 16S, ATP6; nuclear: ATPsβ, ITS) and microscopic skeletal measurements. Mitochondrial markers and the ITS region revealed four distinct clades: I) M. patula/M. verrilli, II) M. cf. incrassata, III) M. capitata, IV) M. dilatata/M. flabellata/M. cf. turgescens. These clades are likely to occur outside of Hawai'i according to mitochondrial control region haplotypes from previous studies. The ATPsβ intron data showed a pattern often interpreted as resulting from hybridization and introgression; however, incomplete lineage sorting may be more likely since the multicopy nuclear ITS region was consistent with the mitochondrial data. Furthermore, principal components analysis (PCA) of skeletal microstructure was concordant with the mitochondrial clades, while nominal taxa overlapped. The size and shape of verrucae or papillae contributed most to identifying groups, while colony-level morphology was highly variable. It is not yet clear if these species complexes represent population-level variation or incipient speciation (CA<1MYA), two alternatives that have very different conservation implications. This study highlights the difficulty in understanding the scale of genetic and morphological variation that corresponds to species as opposed to population-level variation, information that is essential for conservation and for understanding coral biodiversity.

mCSF1, a nucleus-encoded CRM protein required for the processing of many mitochondrial introns, is involved in the biogenesis of respiratory complexes I and IV in Arabidopsis.

PubMed

Zmudjak, Michal; Colas des Francs-Small, Catherine; Keren, Ido; Shaya, Felix; Belausov, Eduard; Small, Ian; Ostersetzer-Biran, Oren

2013-07-01

The coding regions of many mitochondrial genes in plants are interrupted by intervening sequences that are classified as group II introns. Their splicing is essential for the expression of the genes they interrupt and hence for respiratory function, and is facilitated by various protein cofactors. Despite the importance of these cofactors, only a few of them have been characterized. CRS1-YhbY domain (CRM) is a recently recognized RNA-binding domain that is present in several characterized splicing factors in plant chloroplasts. The Arabidopsis genome encodes 16 CRM proteins, but these are largely uncharacterized. Here, we analyzed the intracellular location of one of these hypothetical proteins in Arabidopsis, mitochondrial CAF-like splicing factor 1 (mCSF1; At4 g31010), and analyzed the growth phenotypes and organellar activities associated with mcsf1 mutants in plants. Our data indicated that mCSF1 resides within mitochondria and its functions are essential during embryogenesis. Mutant plants with reduced mCSF1 displayed inhibited germination and retarded growth phenotypes that were tightly associated with reduced complex I and IV activities. Analogously to the functions of plastid-localized CRM proteins, analysis of the RNA profiles in wildtype and mcsf1 plants showed that mCSF1 acts in the splicing of many of the group II intron RNAs in Arabidopsis mitochondria. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Inland post-glacial dispersal in East Asia revealed by mitochondrial haplogroup M9a'b.

PubMed

Peng, Min-Sheng; Palanichamy, Malliya Gounder; Yao, Yong-Gang; Mitra, Bikash; Cheng, Yao-Ting; Zhao, Mian; Liu, Jia; Wang, Hua-Wei; Pan, Hui; Wang, Wen-Zhi; Zhang, A-Mei; Zhang, Wen; Wang, Dong; Zou, Yang; Yang, Yang; Chaudhuri, Tapas Kumar; Kong, Qing-Peng; Zhang, Ya-Ping

2011-01-10

Archaeological studies have revealed a series of cultural changes around the Last Glacial Maximum in East Asia; whether these changes left any signatures in the gene pool of East Asians remains poorly indicated. To achieve deeper insights into the demographic history of modern humans in East Asia around the Last Glacial Maximum, we extensively analyzed mitochondrial DNA haplogroup M9a'b, a specific haplogroup that was suggested to have some potential for tracing the migration around the Last Glacial Maximum in East Eurasia. A total of 837 M9a'b mitochondrial DNAs (583 from the literature, while the remaining 254 were newly collected in this study) pinpointed from over 28,000 subjects residing across East Eurasia were studied here. Fifty-nine representative samples were further selected for total mitochondrial DNA sequencing so we could better understand the phylogeny within M9a'b. Based on the updated phylogeny, an extensive phylogeographic analysis was carried out to reveal the differentiation of haplogroup M9a'b and to reconstruct the dispersal histories. Our results indicated that southern China and/or Southeast Asia likely served as the source of some post-Last Glacial Maximum dispersal(s). The detailed dissection of haplogroup M9a'b revealed the existence of an inland dispersal in mainland East Asia during the post-glacial period. It was this dispersal that expanded not only to western China but also to northeast India and the south Himalaya region. A similar phylogeographic distribution pattern was also observed for haplogroup F1c, thus substantiating our proposition. This inland post-glacial dispersal was in agreement with the spread of the Mesolithic culture originating in South China and northern Vietnam.

Positioning the Red Deer (Cervus elaphus) Hunted by the Tyrolean Iceman into a Mitochondrial DNA Phylogeny

PubMed Central

Olivieri, Cristina; Marota, Isolina; Rizzi, Ermanno; Ermini, Luca; Fusco, Letizia; Pietrelli, Alessandro; De Bellis, Gianluca; Rollo, Franco; Luciani, Stefania

2014-01-01

In the last years several phylogeographic studies of both extant and extinct red deer populations have been conducted. Three distinct mitochondrial lineages (western, eastern and North-African/Sardinian) have been identified reflecting different glacial refugia and postglacial recolonisation processes. However, little is known about the genetics of the Alpine populations and no mitochondrial DNA sequences from Alpine archaeological specimens are available. Here we provide the first mitochondrial sequences of an Alpine Copper Age Cervus elaphus. DNA was extracted from hair shafts which were part of the remains of the clothes of the glacier mummy known as the Tyrolean Iceman or Ötzi (5,350–5,100 years before present). A 2,297 base pairs long fragment was sequenced using a mixed sequencing procedure based on PCR amplifications and 454 sequencing of pooled amplification products. We analyzed the phylogenetic relationships of the Alpine Copper Age red deer's haplotype with haplotypes of modern and ancient European red deer. The phylogenetic analyses showed that the haplotype of the Alpine Copper Age red deer falls within the western European mitochondrial lineage in contrast with the current populations from the Italian Alps belonging to the eastern lineage. We also discussed the phylogenetic relationships of the Alpine Copper Age red deer with the populations from Mesola Wood (northern Italy) and Sardinia. PMID:24988290

CaMKII determines mitochondrial stress responses in heart

PubMed Central

Joiner, Mei-ling A.; Koval, Olha M.; Jingdong, Li; He, B. Julie; Allamargot, Chantal; Gao, Zhan; Luczak, Elizabeth D.; Hall, Duane D.; Fink, Brian D.; Chen, Biyi; Yang, Jinying; Moore, Steven A.; Scholz, Thomas D.; Strack, Stefan; Mohler, Peter J.; Sivitz, William I.; Song, Long-Sheng; Anderson, Mark E.

2012-01-01

Myocardial cell death is initiated by excessive mitochondrial Ca2+ entry, causing Ca2+ overload, mitochondrial permeability transition pore (mPTP) opening and dissipation of the mitochondrial inner membrane potential (ΔΨm)1,2. However, the signaling pathways that control mitochondrial Ca2+ entry through the inner membrane mitochondrial Ca2+ uniporter (MCU)3–5 are not known. The multifunctional Ca2+ and calmodulin-dependent protein kinase II (CaMKII) is activated in ischemia reperfusion (I/R), myocardial infarction (MI) and neurohumoral injury, common causes of myocardial death and heart failure, suggesting CaMKII could couple disease stress to mitochondrial injury. Here we show that CaMKII promotes mPTP opening and myocardial death by increasing MCU current (IMCU). Mitochondrial-targeted CaMKII inhibitory protein or cyclosporin A (CsA), an mPTP antagonist with clinical efficacy in I/R injury6, equivalently prevent mPTP opening, ΔΨm deterioration and diminish mitochondrial disruption and programmed cell death in response to I/R injury. Mice with myocardial and mitochondrial-targeted CaMKII inhibition are resistant to I/R injury, MI and neurohumoral injury, suggesting pathological actions of CaMKII are substantially mediated by increasing IMCU. Our findings identify CaMKII activity as a central mechanism for mitochondrial Ca2+ entry and suggest mitochondrial-targeted CaMKII inhibition could prevent or reduce myocardial death and heart failure dysfunction in response to common experimental forms of pathophysiological stress. PMID:23051746

A whole mitochondrial genome screening in a MELAS patient: A novel mitochondrial tRNA{sup Val} mutation

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

Mezghani, Najla; Mnif, Mouna; Kacem, Maha

2011-04-22

Highlights: {yields} We report a young Tunisian patient with clinical features of MELAS syndrome. {yields} Reported mitochondrial mutations were absent after a mutational screening of the whole mtDNA. {yields} We described a novel m.1640A>G mutation in the tRNA{sup Val} gene which was absent in 150 controls. {yields} Mitochondrial deletions and POLG1 gene mutations were absent. {yields} The m.1640A>G mutation could be associated to MELAS syndrome. -- Abstract: Mitochondrial encephalopathy, lactic acidosis and strokelike episodes (MELAS) syndrome is a mitochondrial disorder characterized by a wide variety of clinical presentations and a multisystemic organ involvement. In this study, we report a Tunisianmore » girl with clinical features of MELAS syndrome who was negative for the common m.3243A>G mutation, but also for the reported mitochondrial DNA (mtDNA) mutations and deletions. Screening of the entire mtDNA genome showed several known mitochondrial variants besides to a novel transition m.1640A>G affecting a wobble adenine in the anticodon stem region of the tRNA{sup Val}. This nucleotide was conserved and it was absent in 150 controls suggesting its pathogenicity. In addition, no mutations were found in the nuclear polymerase gamma-1 gene (POLG1). These results suggest further investigation nuclear genes encoding proteins responsible for stability and structural components of the mtDNA or to the oxidative phosphorylation machinery to explain the phenotypic variability in the studied family.« less

Complete mitochondrial genome of the aluminum-tolerant fungus Rhodotorula taiwanensis RS1 and comparative analysis of Basidiomycota mitochondrial genomes

PubMed Central

Zhao, Xue Qiang; Aizawa, Tomoko; Schneider, Jessica; Wang, Chao; Shen, Ren Fang; Sunairi, Michio

2013-01-01

The complete mitochondrial genome of Rhodotorula taiwanensis RS1, an aluminum-tolerant Basidiomycota fungus, was determined and compared with the known mitochondrial genomes of 12 Basidiomycota species. The mitochondrial genome of R. taiwanensis RS1 is a circular DNA molecule of 40,392 bp and encodes the typical 15 mitochondrial proteins, 23 tRNAs, and small and large rRNAs as well as 10 intronic open reading frames. These genes are apparently transcribed in two directions and do not show syntenies in gene order with other investigated Basidiomycota species. The average G+C content (41%) of the mitochondrial genome of R. taiwanensis RS1 is the highest among the Basidiomycota species. Two introns were detected in the sequence of the atp9 gene of R. taiwanensis RS1, but not in that of other Basidiomycota species. Rhodotorula taiwanensis is the first species of the genus Rhodotorula whose full mitochondrial genome has been sequenced; and the data presented here supply valuable information for understanding the evolution of fungal mitochondrial genomes and researching the mechanism of aluminum tolerance in microorganisms. PMID:23427135

Application of a random walk model to geographic distributions of animal mitochondrial DNA variation.

PubMed

Neigel, J E; Avise, J C

1993-12-01

In rapidly evolving molecules, such as animal mitochondrial DNA, mutations that delineate specific lineages may not be dispersed at sufficient rates to attain an equilibrium between genetic drift and gene flow. Here we predict conditions that lead to nonequilibrium geographic distributions of mtDNA lineages, test the robustness of these predictions and examine mtDNA data sets for consistency with our model. Under a simple isolation by distance model, the variance of an mtDNA lineage's geographic distribution is expected be proportional to its age. Simulation results indicated that this relationship is fairly robust. Analysis of mtDNA data from natural populations revealed three qualitative distributional patterns: (1) significant departure of lineage structure from equilibrium geographic distributions, a pattern exhibited in three rodent species with limited dispersal; (2) nonsignificant departure from equilibrium expectations, exhibited by two avian and two marine fish species with potentials for relatively long-distance dispersal; and (3) a progression from nonequilibrium distributions for younger lineages to equilibrium distributions for older lineages, a condition displayed by one surveyed avian species. These results demonstrate the advantages of considering mutation and genealogy in the interpretation of mtDNA geographic variation.

Loss of Drp1 function alters OPA1 processing and changes mitochondrial membrane organization

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

Moepert, Kristin; Hajek, Petr; Frank, Stephan

2009-08-01

RNAi mediated loss of Drp1 function changes mitochondrial morphology in cultured HeLa and HUVEC cells by shifting the balance of mitochondrial fission and fusion towards unopposed fusion. Over time, inhibition of Drp1 expression results in the formation of a highly branched mitochondrial network along with 'bulge'-like structures. These changes in mitochondrial morphology are accompanied by a reduction in levels of Mitofusin 1 (Mfn1) and 2 (Mfn2) and a modified proteolytic processing of OPA1 isoforms, resulting in the inhibition of cell proliferation. In addition, our data imply that bulge formation is driven by Mfn1 action along with particular proteolytic short-OPA1 (s-OPA1)more » variants: Loss of Mfn2 in the absence of Drp1 results in an increase of Mfn1 levels along with processed s-OPA1-isoforms, thereby enhancing continuous 'fusion' and bulge formation. Moreover, bulge formation might reflect s-OPA1 mitochondrial membrane remodeling activity, resulting in the compartmentalization of cytochrome c deposits. The proteins Yme1L and PHB2 appeared not associated with the observed enhanced OPA1 proteolysis upon RNAi of Drp1, suggesting the existence of other OPA1 processing controlling proteins. Taken together, Drp1 appears to affect the activity of the mitochondrial fusion machinery by unbalancing the protein levels of mitofusins and OPA1.« less

Distribution of gene segments of the pandemic A(H1N1) 2009 virus lineage in pig populations.

PubMed

Okuya, K; Matsuu, A; Kawabata, T; Koike, F; Ito, M; Furuya, T; Taneno, A; Akimoto, S; Deguchi, E; Ozawa, M

2018-05-06

Swine influenza viruses (SIVs) are important not only for pig farming, but also for public health. In fact, pandemic A(H1N1) 2009 viruses [A(H1N1)pdm09] were derived from SIVs. Therefore, timely characterization of locally circulating SIVs is necessary for understanding the global status of SIVs. To genetically characterize SIVs circulating in Japanese pig populations, we isolated 24 SIVs of three subtypes (17 H1N1, four H1N2 and three H3N2 strains) from 14 pig farms in Japan from 2013 to 2016. Genetic analyses revealed that the haemagglutinin (HA) and neuraminidase (NA) genes of the 17 H1N1 and the HA gene of one H1N2, A/swine/Aichi/02/2016 (H1N2), SIVs belonged to the A(H1N1)pdm09 lineage. More importantly, all of the remaining six gene segments (i.e., PB1, PB1, PA, NP, M and NS) of the 24 SIVs, regardless of the HA and NA subtype, were also classified as belonging to the A(H1N1)pdm09 lineage. These results indicate that gene segments of A(H1N1)pdm09 lineage are widely distributed in SIVs circulating in Japanese pig populations In addition, the NA gene of A/swine/Aichi/02/2016 (H1N2) shared less than 88.5% nucleotide identity with that of the closest relative A/swine/Miyagi/5/2003 (H1N2), which was isolated in Japan in 2003. These results indicate the sustained circulation of classical H1N2-derived SIVs with remarkable diversity in the NA genes in Japanese pig populations. These findings highlight the necessity of both intensive biosecurity systems and active SIV surveillance in pig populations worldwide for both animal and public health. © 2018 Blackwell Verlag GmbH.

The complete mitochondrial genome of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) in Indo-West Pacific.

PubMed

Hsiao, Chung-Der; Shen, Kang-Ning; Ching, Tzu-Yun; Wang, Ya-Hsien; Ye, Jeng-Jia; Tsai, Shiou-Yi; Wu, Shan-Chun; Chen, Ching-Hung; Wang, Chia-Hui

2016-07-01

In this study, the complete mitogenome sequence of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consists of 16,605 bp, which includes 13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of "lineage A" S. lessoniana is 37.5% for A, 17.4% for C, 9.1% for G, and 35.9% for T and shows 87% identities to "lineage C" S. lessoniana. It is also noticed by its high T + A content (73.4%), two non-coding regions with TA tandem repeats. The complete mitogenome of the cryptic "lineage A" S. lessoniana provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for big-fin reef squid species complex.

Mosaic nature of the mitochondrial proteome: Implications for the origin and evolution of mitochondria.

PubMed

Gray, Michael W

2015-08-18

Comparative studies of the mitochondrial proteome have identified a conserved core of proteins descended from the α-proteobacterial endosymbiont that gave rise to the mitochondrion and was the source of the mitochondrial genome in contemporary eukaryotes. A surprising result of phylogenetic analyses is the relatively small proportion (10-20%) of the mitochondrial proteome displaying a clear α-proteobacterial ancestry. A large fraction of mitochondrial proteins typically has detectable homologs only in other eukaryotes and is presumed to represent proteins that emerged specifically within eukaryotes. A further significant fraction of the mitochondrial proteome consists of proteins with homologs in prokaryotes, but without a robust phylogenetic signal affiliating them with specific prokaryotic lineages. The presumptive evolutionary source of these proteins is quite different in contending models of mitochondrial origin.

Mitochondrial targeting of HIF-1α inhibits hypoxia-induced apoptosis independently of its transcriptional activity.

PubMed

Li, Hong-Sheng; Zhou, Yan-Ni; Li, Lu; Li, Sheng-Fu; Long, Dan; Chen, Xue-Lu; Zhang, Jia-Bi; Li, You-Ping; Feng, Li

2018-04-25

The transcription factor hypoxia inducible factor-1α (HIF-1α) mediates adaptive responses to hypoxia by nuclear translocation and regulation of gene expression. Mitochondrial changes are critical for the adaptive response to hypoxia. However, the transcriptional and non-transcriptional mechanisms by which HIF-1α regulates mitochondria under hypoxia are poorly understood. Here, we examined the subcellular localization of HIF-1α in human cells and identified a small fraction of HIF-1α that translocated to the mitochondria after exposure to hypoxia or hypoxia-mimicking pharmacological agents. To probe the function of this HIF-1α population, we ectopically expressed a mitochondrial-targeted form of HIF-1α (mito-HIF-1α). Expression of mito-HIF-1α was sufficient to attenuate apoptosis induced by exposure to hypoxia or H 2 O 2 -induced oxidative stress. Moreover, mito-HIF-1α expression reduced the production of reactive oxygen species, the collapse of mitochondrial membrane potential, and the expression of mitochondrial DNA-encoded mRNA in response to hypoxia. However, these functions of mito-HIF-1α were independent of its conventional transcriptional activity. Finally, the livers of mice with CCl 4 -induced fibrosis showed a progressive increase in HIF-1α association with the mitochondria, indicating the clinical relevance of this finding. These data suggested that mitochondrial HIF-1α protects against apoptosis independently of its well-known role as a transcription factor. Copyright © 2018. Published by Elsevier Inc.

Complete mitochondrial genome of the aluminum-tolerant fungus Rhodotorula taiwanensis RS1 and comparative analysis of Basidiomycota mitochondrial genomes.

PubMed

Zhao, Xue Qiang; Aizawa, Tomoko; Schneider, Jessica; Wang, Chao; Shen, Ren Fang; Sunairi, Michio

2013-04-01

The complete mitochondrial genome of Rhodotorula taiwanensis RS1, an aluminum-tolerant Basidiomycota fungus, was determined and compared with the known mitochondrial genomes of 12 Basidiomycota species. The mitochondrial genome of R. taiwanensis RS1 is a circular DNA molecule of 40,392 bp and encodes the typical 15 mitochondrial proteins, 23 tRNAs, and small and large rRNAs as well as 10 intronic open reading frames. These genes are apparently transcribed in two directions and do not show syntenies in gene order with other investigated Basidiomycota species. The average G+C content (41%) of the mitochondrial genome of R. taiwanensis RS1 is the highest among the Basidiomycota species. Two introns were detected in the sequence of the atp9 gene of R. taiwanensis RS1, but not in that of other Basidiomycota species. Rhodotorula taiwanensis is the first species of the genus Rhodotorula whose full mitochondrial genome has been sequenced; and the data presented here supply valuable information for understanding the evolution of fungal mitochondrial genomes and researching the mechanism of aluminum tolerance in microorganisms. © 2013 The Authors. Published by Blackwell Publishing Ltd.

Molecular analyses reveal two geographic and genetic lineages for tapeworms, Taenia solium and Taenia saginata, from Ecuador using mitochondrial DNA.

PubMed

Solano, Danilo; Navarro, Juan Carlos; León-Reyes, Antonio; Benítez-Ortiz, Washington; Rodríguez-Hidalgo, Richar

2016-12-01

Tapeworms Taenia solium and Taenia saginata are the causative agents of taeniasis/cysticercosis. These are diseases with high medical and veterinary importance due to their impact on public health and rural economy in tropical countries. The re-emergence of T. solium as a result of human migration, the economic burden affecting livestock industry, and the large variability of symptoms in several human cysticercosis, encourage studies on genetic diversity, and the identification of these parasites with molecular phylogenetic tools. Samples collected from the Ecuadorian provinces: Loja, Guayas, Manabí, Tungurahua (South), and Imbabura, Pichincha (North) from 2000 to 2012 were performed under Maximum Parsimony analyses and haplotype networks using partial sequences of mitochondrial DNA, cytochrome oxidase subunit I (COI) and NADH subunit I (NDI), from Genbank and own sequences of Taenia solium and Taenia saginata from Ecuador. Both species have shown reciprocal monophyly, which confirms its molecular taxonomic identity. The COI and NDI genes results suggest phylogenetic structure for both parasite species from south and north of Ecuador. In T. solium, both genes gene revealed greater geographic structure, whereas in T. saginata, the variability for both genes was low. In conclusion, COI haplotype networks of T. solium suggest two geographical events in the introduction of this species in Ecuador (African and Asian lineages) and occurring sympatric, probably through the most common routes of maritime trade between the XV-XIX centuries. Moreover, the evidence of two NDI geographical lineages in T. solium from the north (province of Imbabura) and the south (province of Loja) of Ecuador derivate from a common Indian ancestor open new approaches for studies on genetic populations and eco-epidemiology. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitochondrial control by DRP1 in brain tumor initiating cells.

PubMed

Xie, Qi; Wu, Qiulian; Horbinski, Craig M; Flavahan, William A; Yang, Kailin; Zhou, Wenchao; Dombrowski, Stephen M; Huang, Zhi; Fang, Xiaoguang; Shi, Yu; Ferguson, Ashley N; Kashatus, David F; Bao, Shideng; Rich, Jeremy N

2015-04-01

Brain tumor initiating cells (BTICs) co-opt the neuronal high affinity glucose transporter, GLUT3, to withstand metabolic stress. We investigated another mechanism critical to brain metabolism, mitochondrial morphology, in BTICs. BTIC mitochondria were fragmented relative to non-BTIC tumor cell mitochondria, suggesting that BTICs increase mitochondrial fission. The essential mediator of mitochondrial fission, dynamin-related protein 1 (DRP1), showed activating phosphorylation in BTICs and inhibitory phosphorylation in non-BTIC tumor cells. Targeting DRP1 using RNA interference or pharmacologic inhibition induced BTIC apoptosis and inhibited tumor growth. Downstream, DRP1 activity regulated the essential metabolic stress sensor, AMP-activated protein kinase (AMPK), and targeting AMPK rescued the effects of DRP1 disruption. Cyclin-dependent kinase 5 (CDK5) phosphorylated DRP1 to increase its activity in BTICs, whereas Ca(2+)-calmodulin-dependent protein kinase 2 (CAMK2) inhibited DRP1 in non-BTIC tumor cells, suggesting that tumor cell differentiation induces a regulatory switch in mitochondrial morphology. DRP1 activation correlated with poor prognosis in glioblastoma, suggesting that mitochondrial dynamics may represent a therapeutic target for BTICs.

Mitochondrial dysfunction precedes neurodegeneration in mahogunin (Mgrn1) mutant mice

PubMed Central

Sun, Kaihua; Johnson, Brian S.; Gunn, Teresa M.

2007-01-01

Oxidative stress, ubiquitination defects and mitochondrial dysfunction are commonly associated with neurodegeneration. Mice lacking mahogunin ring finger-1 (MGRN1) or attractin (ATRN) develop age-dependent spongiform neurodegeneration through an unknown mechanism. It has been suggested that they act in a common pathway. As MGRN1 is an E3 ubiquitin ligase, proteomic analysis of Mgrn1 mutant and control brains was performed to explore the hypothesis that loss of MGRN1 causes neurodegeneration via accumulation of its substrates. Many mitochondrial proteins were reduced in Mgrn1 mutants. Subsequent assays confirmed significantly reduced mitochondrial complex IV expression and activity as well as increased oxidative stress in mutant brains. Mitochondrial dysfunction was obvious many months before onset of vacuolation, implicating this as a causative factor. Compatible with the hypothesis that ATRN and MGRN1 act in the same pathway, mitochondrial dysfunction and increased oxidative stress were also observed in the brains of Atrn mutants. Our results suggest that the study of Mgrn1 and Atrn mutant mice will provide insight into a causative molecular mechanism common to many neurodegenerative disorders. PMID:17720281

Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions

PubMed Central

Chaintoutis, Serafeim C.; Diakakis, Nikolaos; Papanastassopoulou, Maria; Banos, Georgios

2015-01-01

Although experimental data regarding cross-protection of horse West Nile virus (WNV) vaccines against lineage 2 infections exist, the cross-protective efficacy of these vaccines under field conditions has not been demonstrated. This study was conducted to evaluate the capability of an inactivated lineage 1 vaccine (Equip WNV) to protect against natural infections from the Nea Santa-Greece-2010 lineage 2 strain. In total, 185 WNV-seronegative horses in Thessaloniki, Greece, were selected during 2 consecutive years (2011 and 2012); 140 were immunized, and 45 were used as controls. Horses were examined for signs compatible with WNV infection. Neutralizing antibody titers against the Greek strain and the PaAn001/France lineage 1 strain were determined in immunized horses. WNV circulation was detected during both years in the study area. It was estimated that 37% and 27% of the horses were infected during 2011 and 2012, respectively. Three control animals developed clinical signs, and the WNV diagnosis was confirmed. Signs related to WNV infection were not observed in the vaccinated animals. The nonvaccinated animals had a 7.58% ± 1.82% higher chance of exhibiting signs than immunized animals (P < 0.05). Neutralizing antibodies raised against both strains in all immunized horses were detectable 1 month after the initial vaccination course. The cross-protective capacity of the lowest titer (1:40) was evident in 19 animals which were subsequently infected and did not exhibit signs. Neutralizing antibodies were detectable until the annual booster, when strong anamnestic responses were observed (geometrical mean titer ratio [GMTR] for lineage 1 of 30.2; GMTR for lineage 2 of 27.5). The results indicate that Equip WNV is capable of inducing cross-protection against natural infections from a virulent lineage 2 WNV strain in horses. PMID:26178384

The UK MRC Mitochondrial Disease Patient Cohort Study: clinical phenotypes associated with the m.3243A>G mutation--implications for diagnosis and management.

PubMed

Nesbitt, Victoria; Pitceathly, Robert D S; Turnbull, Doug M; Taylor, Robert W; Sweeney, Mary G; Mudanohwo, Ese E; Rahman, Shamima; Hanna, Michael G; McFarland, Robert

2013-08-01

Population-based studies suggest the m.3243A>G mutation in MTTL1 is the most common disease-causing mtDNA mutation, with a carrier rate of 1 in 400 people. The m.3243A>G mutation is associated with several clinical syndromes including mitochondrial encephalopathy lactic acidosis and stroke-like episodes (MELAS), maternally inherited deafness and diabetes (MIDD) and progressive external ophthalmoplegia (PEO). Many patients affected by this mutation exhibit a clinical phenotype that does not fall within accepted criteria for the currently recognised classical mitochondrial syndromes. We have defined the phenotypic spectrum associated with the m.3243A>G mtDNA mutation in 129 patients, from 83 unrelated families, recruited to the Mitochondrial Disease Patient Cohort Study UK. 10% of patients exhibited a classical MELAS phenotype, 30% had MIDD, 6% MELAS/MIDD, 2% MELAS/chronic PEO (CPEO) and 5% MIDD/CPEO overlap syndromes. 6% had PEO and other features of mitochondrial disease not consistent with another recognised syndrome. Isolated sensorineural hearing loss occurred in 3%. 28% of patients demonstrated a panoply of clinical features, which were not consistent with any of the classical syndromes associated with the m.3243A>G mutation. 9% of individuals harbouring the mutation were clinically asymptomatic. Following this study we propose guidelines for screening and for the management of confirmed cases.

Use of polyclonal anti-myeloperoxidase antibody in myeloid lineage determination.

PubMed

Karnik, M P; Nair, C N; Zingde, S M; Gothoskar, B P; Zachariah, L; Barbhaya, S; Advani, S H

1994-12-01

This study reports the production of a rabbit polyclonal antibody to myeloperoxidase (MPO) and its use in ascertaining the myeloid lineage of blasts in leukaemia. Comparison of the immunocytochemical stain using the anti-MPO antibody with the routine cytochemical methodology showed that the former was more sensitive. In all subtypes of acute myeloid leukaemia (AML; 72 patients, M1-M6) greater number of MPO positive blast cells were observed by immunocytochemistry, the highest being in the promyelocytic leukaemia. It was also extremely specific for cells of the myeloid lineage as it did not react with blasts from acute lymphoblastic (50 patients) and megakaryoblastic leukaemias (1 patient). In addition, it proved most useful for the lineage determination of blasts from patients with undifferentiated acute leukaemias (AUL) and those with chronic myeloid leukaemia in blast crisis (CML-BC). Out of 8 patients of AULs, 6 were classified as acute myeloblastic leukaemia due to their reactivity to the anti-MPO antibody. Similarly, out of 12 patients of chronic myeloid leukaemia in blast crisis, blasts from 8 showed reactivity to this antibody and thus could be identified as belonging to the myeloid lineage and/or of the mixed blast crisis type.

Folliculin (Flcn) inactivation leads to murine cardiac hypertrophy through mTORC1 deregulation

PubMed Central

Hasumi, Yukiko; Baba, Masaya; Hasumi, Hisashi; Huang, Ying; Lang, Martin; Reindorf, Rachel; Oh, Hyoung-bin; Sciarretta, Sebastiano; Nagashima, Kunio; Haines, Diana C.; Schneider, Michael D.; Adelstein, Robert S.; Schmidt, Laura S.; Sadoshima, Junichi; Marston Linehan, W.

2014-01-01

Cardiac hypertrophy, an adaptive process that responds to increased wall stress, is characterized by the enlargement of cardiomyocytes and structural remodeling. It is stimulated by various growth signals, of which the mTORC1 pathway is a well-recognized source. Here, we show that loss of Flcn, a novel AMPK–mTOR interacting molecule, causes severe cardiac hypertrophy with deregulated energy homeostasis leading to dilated cardiomyopathy in mice. We found that mTORC1 activity was upregulated in Flcn-deficient hearts, and that rapamycin treatment significantly reduced heart mass and ameliorated cardiac dysfunction. Phospho-AMP-activated protein kinase (AMPK)-alpha (T172) was reduced in Flcn-deficient hearts and nonresponsive to various stimulations including metformin and AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide). ATP levels were elevated and mitochondrial function was increased in Flcn-deficient hearts, suggesting that excess energy resulting from up-regulated mitochondrial metabolism under Flcn deficiency might attenuate AMPK activation. Expression of Ppargc1a, a central molecule for mitochondrial metabolism, was increased in Flcn-deficient hearts and indeed, inactivation of Ppargc1a in Flcn-deficient hearts significantly reduced heart mass and prolonged survival. Ppargc1a inactivation restored phospho-AMPK-alpha levels and suppressed mTORC1 activity in Flcn-deficient hearts, suggesting that up-regulated Ppargc1a confers increased mitochondrial metabolism and excess energy, leading to inactivation of AMPK and activation of mTORC1. Rapamycin treatment did not affect the heart size of Flcn/Ppargc1a doubly inactivated hearts, further supporting the idea that Ppargc1a is the critical element leading to deregulation of the AMPK–mTOR-axis and resulting in cardiac hypertrophy under Flcn deficiency. These data support an important role for Flcn in cardiac homeostasis in the murine model. PMID:24908670

Palindromic Genes in the Linear Mitochondrial Genome of the Nonphotosynthetic Green Alga Polytomella magna

PubMed Central

Smith, David Roy; Hua, Jimeng; Archibald, John M.; Lee, Robert W.

2013-01-01

Organelle DNA is no stranger to palindromic repeats. But never has a mitochondrial or plastid genome been described in which every coding region is part of a distinct palindromic unit. While sequencing the mitochondrial DNA of the nonphotosynthetic green alga Polytomella magna, we uncovered precisely this type of genic arrangement. The P. magna mitochondrial genome is linear and made up entirely of palindromes, each containing 1–7 unique coding regions. Consequently, every gene in the genome is duplicated and in an inverted orientation relative to its partner. And when these palindromic genes are folded into putative stem-loops, their predicted translational start sites are often positioned in the apex of the loop. Gel electrophoresis results support the linear, 28-kb monomeric conformation of the P. magna mitochondrial genome. Analyses of other Polytomella taxa suggest that palindromic mitochondrial genes were present in the ancestor of the Polytomella lineage and lost or retained to various degrees in extant species. The possible origins and consequences of this bizarre genomic architecture are discussed. PMID:23940100

Newly resolved relationships in an early land plant lineage: Bryophyta class Sphagnopsida (peat mosses).

PubMed

Shaw, A Jonathan; Cox, Cymon J; Buck, William R; Devos, Nicolas; Buchanan, Alex M; Cave, Lynette; Seppelt, Rodney; Shaw, Blanka; Larraín, Juan; Andrus, Richard; Greilhuber, Johann; Temsch, Eva M

2010-09-01

The Sphagnopsida, an early-diverging lineage of mosses (phylum Bryophyta), are morphologically and ecologically unique and have profound impacts on global climate. The Sphagnopsida are currently classified in two genera, Sphagnum (peat mosses) with some 350-500 species and Ambuchanania with one species. An analysis of phylogenetic relationships among species and genera in the Sphagnopsida were conducted to resolve major lineages and relationships among species within the Sphagnopsida. • Phylogenetic analyses of nucleotide sequences from the nuclear, plastid, and mitochondrial genomes (11 704 nucleotides total) were conducted and analyzed using maximum likelihood and Bayesian inference employing seven different substitution models of varying complexity. • Phylogenetic analyses resolved three lineages within the Sphagnopsida: (1) Sphagnum sericeum, (2) S. inretortum plus Ambuchanania leucobryoides, and (3) all remaining species of Sphagnum. Sister group relationships among these three clades could not be resolved, but the phylogenetic results indicate that the highly divergent morphology of A. leucobryoides is derived within the Sphagnopsida rather than plesiomorphic. A new classification is proposed for class Sphagnopsida, with one order (Sphagnales), three families, and four genera. • The Sphagnopsida are an old lineage within the phylum Bryophyta, but the extant species of Sphagnum represent a relatively recent radiation. It is likely that additional species critical to understanding the evolution of peat mosses await discovery, especially in the southern hemisphere.

Monoamine oxidase-A physically interacts with presenilin-1(M146V) in the mouse cortex.

PubMed

Wei, Zelan; Gabriel, Geraldine G; Rui, Lewei; Cao, Xia; Pennington, Paul R; Chlan-Fourney, Jennifer; Nazarali, Adil J; Baker, Glen B; Mousseau, Darrell D

2012-01-01

The concentration of presenilin-1 (PS-1) protein at the mitochondrial-associated aspect of the endoplasmic reticulum supports the potential for a mitochondrial influence of PS-1. Given that carriers of certain Alzheimer's disease (AD)-related PS-1 variants are predisposed to clinical depression and that depression has been historically associated with the mitochondrial enzyme, monoamine oxidase-A (MAO-A), we investigated cortical MAO-A function in the AD-related PS-1(M146V) knock-in mouse. The MAO-A system was clearly altered in the PS-1(M146V) mouse as revealed by (a) a mismatch between MAO-A protein expression and MAO-A activity; (b) changes in MAO-A-mediated monoaminergic neurotransmitter metabolism; (c) changes in non-cognitive behavior following treatment with the irreversible MAO-A inhibitor clorgyline; and (d) an increase in the potency of clorgyline in these same mice. We next investigated whether PS-1(M146V) could be influencing MAO-A directly. We observed (a) an enhanced MAO-A activity in necropsied PS-1(M146V) mouse cortical extracts incubated with DAPT (a PS-1 substrate-competitor); (b) the proximity of PS-1 with MAO-A and mitochondrial markers in cortical sections and in primary cortical neurons; (c) the co-segregation and co-immunoprecipitation of PS-1 and MAO-A within the mitochondrial fraction; and (d) the co-immunoprecipitation of overexpressed PS-1(M146V) and MAO-A proteins from N2a lysates. The PS-1(ΔEx9) and PS-1(D257A) variants, known to have low substrate-binding capacity, co-immunoprecipitated weakly with MAO-A. These combined data support a physical interaction between PS-1 and MAO-A that could influence MAO-A activity and contribute to the monoaminergic disruptions common to disorders as seemingly diverse as depression and AD.

Reduced evolutionary rates in HIV-1 reveal extensive latency periods among replicating lineages.

PubMed

Immonen, Taina T; Leitner, Thomas

2014-10-16

HIV-1 can persist for the duration of a patient's life due in part to its ability to hide from the immune system, and from antiretroviral drugs, in long-lived latent reservoirs. Latent forms of HIV-1 may also be disproportionally involved in transmission. Thus, it is important to detect and quantify latency in the HIV-1 life cycle. We developed a novel molecular clock-based phylogenetic tool to investigate the prevalence of HIV-1 lineages that have experienced latency. The method removes alternative sources that may affect evolutionary rates, such as hypermutation, recombination, and selection, to reveal the contribution of generation-time effects caused by latency. Our method was able to recover latent lineages with high specificity and sensitivity, and low false discovery rates, even on relatively short branches on simulated phylogenies. Applying the tool to HIV-1 sequences from 26 patients, we show that the majority of phylogenetic lineages have been affected by generation-time effects in every patient type, whether untreated, elite controller, or under effective or failing treatment. Furthermore, we discovered extensive effects of latency in sequence data (gag, pol, and env) from reservoirs as well as in the replicating plasma population. To better understand our phylogenetic findings, we developed a dynamic model of virus-host interactions to investigate the proportion of lineages in the actively replicating population that have ever been latent. Assuming neutral evolution, our dynamic modeling showed that under most parameter conditions, it is possible for a few activated latent viruses to propagate so that in time, most HIV-1 lineages will have been latent at some time in their past. These results suggest that cycling in and out of latency plays a major role in the evolution of HIV-1. Thus, no aspect of HIV-1 evolution can be fully understood without considering latency - including treatment, drug resistance, immune evasion, transmission, and pathogenesis.

Mitochondrial DNA haplogroup phylogeny of the dog: Proposal for a cladistic nomenclature.

PubMed

Fregel, Rosa; Suárez, Nicolás M; Betancor, Eva; González, Ana M; Cabrera, Vicente M; Pestano, José

2015-05-01

Canis lupus familiaris mitochondrial DNA analysis has increased in recent years, not only for the purpose of deciphering dog domestication but also for forensic genetic studies or breed characterization. The resultant accumulation of data has increased the need for a normalized and phylogenetic-based nomenclature like those provided for human maternal lineages. Although a standardized classification has been proposed, haplotype names within clades have been assigned gradually without considering the evolutionary history of dog mtDNA. Moreover, this classification is based only on the D-loop region, proven to be insufficient for phylogenetic purposes due to its high number of recurrent mutations and the lack of relevant information present in the coding region. In this study, we design 1) a refined mtDNA cladistic nomenclature from a phylogenetic tree based on complete sequences, classifying dog maternal lineages into haplogroups defined by specific diagnostic mutations, and 2) a coding region SNP analysis that allows a more accurate classification into haplogroups when combined with D-loop sequencing, thus improving the phylogenetic information obtained in dog mitochondrial DNA studies. Copyright © 2015 Elsevier B.V. All rights reserved.

An analysis of correspondence between unique rabies virus variants and divergent big brown bat (Eptesicus fuscus) mitochondrial DNA lineages

USGS Publications Warehouse

Neubaum, M.A.; Shankar, V.; Douglas, M.R.; Douglas, M.E.; O'Shea, T.J.; Rupprecht, C.E.

2008-01-01

The literature supports that unique rabies virus (RABV) variants are often compartmentalized in different species of bats. In Colorado, two divergent mtDNA lineages of big brown bats (Eptesicus fuscus) co-occur. RABV associated with this species also segregates into two clades. We hypothesized that unique RABV variants might be associated with mtDNA lineages of Colorado big brown bats. DNA was extracted from brain tissue of rabid big brown bats, the ND2 gene was amplified to determine mtDNA lineage, and the lineage was compared to a previously derived phylogenetic analysis of the RABV N gene. No correspondence was found between host bat lineage and RABV variant. ?? 2008 Springer-Verlag.

Mitochondrial DNA perspective of Serbian genetic diversity.

PubMed

Davidovic, Slobodan; Malyarchuk, Boris; Aleksic, Jelena M; Derenko, Miroslava; Topalovic, Vladanka; Litvinov, Andrey; Stevanovic, Milena; Kovacevic-Grujicic, Natasa

2015-03-01

Although south-Slavic populations have been studied to date from various aspects, the population of Serbia, occupying the central part of the Balkan Peninsula, is still genetically understudied at least at the level of mitochondrial DNA (mtDNA) variation. We analyzed polymorphisms of the first and the second mtDNA hypervariable segments (HVS-I and HVS-II) and informative coding-region markers in 139 Serbians to shed more light on their mtDNA variability, and used available data on other Slavic and neighboring non-Slavic populations to assess their interrelations in a broader European context. The contemporary Serbian mtDNA profile is consistent with the general European maternal landscape having a substantial proportion of shared haplotypes with eastern, central, and southern European populations. Serbian population was characterized as an important link between easternmost and westernmost south-Slavic populations due to the observed lack of genetic differentiation with all other south-Slavic populations and its geographical positioning within the Balkan Peninsula. An increased heterogeneity of south Slavs, most likely mirroring turbulent demographic events within the Balkan Peninsula over time (i.e., frequent admixture and differential introgression of various gene pools), and a marked geographical stratification of Slavs to south-, east-, and west-Slavic groups, were also found. A phylogeographic analyses of 20 completely sequenced Serbian mitochondrial genomes revealed not only the presence of mtDNA lineages predominantly found within the Slavic gene pool (U4a2a*, U4a2a1, U4a2c, U4a2g, HV10), supporting a common Slavic origin, but also lineages that may have originated within the southern Europe (H5*, H5e1, H5a1v) and the Balkan Peninsula in particular (H6a2b and L2a1k). © 2014 Wiley Periodicals, Inc.

The postglacial recolonization of Northern Europe by Rana arvalis as revealed by microsatellite and mitochondrial DNA analyses.

PubMed

Knopp, T; Merilä, J

2009-02-01

The postglacial history of the moor frog (Rana arvalis) in Northern Europe was investigated with the aid of eight variable microsatellite loci and a 661 bp sequence of the mitochondrial cytochrome b gene. A division between eastern and western mitochondrial lineages was discovered, supporting two recolonization routes to Fennoscandia since the last glacial maximum. This result was corroborated by the microsatellite data, which revealed a contact zone between the two lineages in Northern Sweden. These findings add to the increasing evidence that an intraspecific genetic biodiversity founded on the existence of eastern and western clades is a common element in Fennoscandian fauna and flora.

Liver-enriched transcription factors are critical for the expression of hepatocyte marker genes in mES-derived hepatocyte-lineage cells.

PubMed

Kheolamai, Pakpoom; Dickson, Alan J

2009-04-23

Induction of stem cell differentiation toward functional hepatocytes is hampered by lack of knowledge of the hepatocyte differentiation processes. The overall objective of this project is to characterize key stages in the hepatocyte differentiation process. We established a mouse embryonic stem (mES) cell culture system which exhibited changes in gene expression profiles similar to those observed in the development of endodermal and hepatocyte-lineage cells previously described in the normal mouse embryo. Transgenic mES cells were established that permitted isolation of enriched hepatocyte-lineage populations. This approach has isolated mES-derived hepatocyte-lineage cells that express several markers of mature hepatocytes including albumin, glucose-6-phosphatase, tyrosine aminotransferase, cytochrome P450-3a, phosphoenolpyruvate carboxykinase and tryptophan 2,3-dioxygenase. In addition, our results show that the up-regulation of the expression levels of hepatocyte nuclear factor-3alpha, -4alpha, -6, and CCAAT-enhancer binding protein-beta might be critical for passage into late-stage differentiation towards functional hepatocytes. These data present important steps for definition of regulatory phenomena that direct specific cell fate determination. The mES cell culture system generated in this study provides a model for studying transition between stages of the hepatocyte development and has significant potential value for studying the molecular basis of hepatocyte differentiation in vitro.

Activation of IGF-1 and insulin signaling pathways ameliorate mitochondrial function and energy metabolism in Huntington's Disease human lymphoblasts.

PubMed

Naia, Luana; Ferreira, I Luísa; Cunha-Oliveira, Teresa; Duarte, Ana I; Ribeiro, Márcio; Rosenstock, Tatiana R; Laço, Mário N; Ribeiro, Maria J; Oliveira, Catarina R; Saudou, Frédéric; Humbert, Sandrine; Rego, A Cristina

2015-02-01

Huntington's disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine repeat expansion in the huntingtin protein. Mitochondrial dysfunction associated with energy failure plays an important role in this untreated pathology. In the present work, we used lymphoblasts obtained from HD patients or unaffected parentally related individuals to study the protective role of insulin-like growth factor 1 (IGF-1) versus insulin (at low nM) on signaling and metabolic and mitochondrial functions. Deregulation of intracellular signaling pathways linked to activation of insulin and IGF-1 receptors (IR,IGF-1R), Akt, and ERK was largely restored by IGF-1 and, at a less extent, by insulin in HD human lymphoblasts. Importantly, both neurotrophic factors stimulated huntingtin phosphorylation at Ser421 in HD cells. IGF-1 and insulin also rescued energy levels in HD peripheral cells, as evaluated by increased ATP and phosphocreatine, and decreased lactate levels. Moreover, IGF-1 effectively ameliorated O2 consumption and mitochondrial membrane potential (Δψm) in HD lymphoblasts, which occurred concomitantly with increased levels of cytochrome c. Indeed, constitutive phosphorylation of huntingtin was able to restore the Δψm in lymphoblasts expressing an abnormal expansion of polyglutamines. HD lymphoblasts further exhibited increased intracellular Ca(2+) levels before and after exposure to hydrogen peroxide (H2O2), and decreased mitochondrial Ca(2+) accumulation, being the later recovered by IGF-1 and insulin in HD lymphoblasts pre-exposed to H2O2. In summary, the data support an important role for IR/IGF-1R mediated activation of signaling pathways and improved mitochondrial and metabolic function in HD human lymphoblasts.

A complete Neandertal mitochondrial genome sequence determined by high-throughput sequencing

PubMed Central

Green, Richard E.; Malaspinas, Anna-Sapfo; Krause, Johannes; Briggs, Adrian W.; Johnson, Philip L. F.; Uhler, Caroline; Meyer, Matthias; Good, Jeffrey M.; Maricic, Tomislav; Stenzel, Udo; Prüfer, Kay; Siebauer, Michael; Burbano, Hernán A.; Ronan, Michael; Rothberg, Jonathan M.; Egholm, Michael; Rudan, Pavao; Brajković, Dejana; Kućan, Željko; Gušić, Ivan; Wikström, Mårten; Laakkonen, Liisa; Kelso, Janet; Slatkin, Montgomery; Pääbo, Svante

2008-01-01

Summary A complete mitochondrial (mt) genome sequence was reconstructed from a 38,000-year-old Neandertal individual using 8,341 mtDNA sequences identified among 4.8 Gb of DNA generated from ~0.3 grams of bone. Analysis of the assembled sequence unequivocally establishes that the Neandertal mtDNA falls outside the variation of extant human mtDNAs and allows an estimate of the divergence date between the two mtDNA lineages of 660,000±140,000 years. Of the 13 proteins encoded in the mtDNA, subunit 2 of cytochrome c oxidase of the mitochondrial electron transport chain has experienced the largest number of amino acid substitutions in human ancestors since the separation from Neandertals. There is evidence that purifying selection in the Neandertal mtDNA was reduced compared to other primate lineages suggesting that the effective population size of Neandertals was small. PMID:18692465

β-Cell deletion of Nr4a1 and Nr4a3 nuclear receptors impedes mitochondrial respiration and insulin secretion.

PubMed

Reynolds, Merrick S; Hancock, Chad R; Ray, Jason D; Kener, Kyle B; Draney, Carrie; Garland, Kevin; Hardman, Jeremy; Bikman, Benjamin T; Tessem, Jeffery S

2016-07-01

β-Cell insulin secretion is dependent on proper mitochondrial function. Various studies have clearly shown that the Nr4a family of orphan nuclear receptors is essential for fuel utilization and mitochondrial function in liver, muscle, and adipose. Previously, we have demonstrated that overexpression of Nr4a1 or Nr4a3 is sufficient to induce proliferation of pancreatic β-cells. In this study, we examined whether Nr4a expression impacts pancreatic β-cell mitochondrial function. Here, we show that β-cell mitochondrial respiration is dependent on the nuclear receptors Nr4a1 and Nr4a3. Mitochondrial respiration in permeabilized cells was significantly decreased in β-cells lacking Nr4a1 or Nr4a3. Furthermore, respiration rates of intact cells deficient for Nr4a1 or Nr4a3 in the presence of 16 mM glucose resulted in decreased glucose mediated oxygen consumption. Consistent with this reduction in respiration, a significant decrease in glucose-stimulated insulin secretion rates is observed with deletion of Nr4a1 or Nr4a3. Interestingly, the changes in respiration and insulin secretion occur without a reduction in mitochondrial content, suggesting decreased mitochondrial function. We establish that knockdown of Nr4a1 and Nr4a3 results in decreased expression of the mitochondrial dehydrogenase subunits Idh3g and Sdhb. We demonstrate that loss of Nr4a1 and Nr4a3 impedes production of ATP and ultimately inhibits glucose-stimulated insulin secretion. These data demonstrate for the first time that the orphan nuclear receptors Nr4a1 and Nr4a3 are critical for β-cell mitochondrial function and insulin secretion. Copyright © 2016 the American Physiological Society.

TGF-β1-Mediated Differentiation of Fibroblasts Is Associated with Increased Mitochondrial Content and Cellular Respiration

PubMed Central

Negmadjanov, Ulugbek; Godic, Zarko; Rizvi, Farhan; Emelyanova, Larisa; Ross, Gracious; Richards, John; Holmuhamedov, Ekhson L.; Jahangir, Arshad

2015-01-01

Objectivs Cytokine-dependent activation of fibroblasts to myofibroblasts, a key event in fibrosis, is accompanied by phenotypic changes with increased secretory and contractile properties dependent on increased energy utilization, yet changes in the energetic profile of these cells are not fully described. We hypothesize that the TGF-β1-mediated transformation of myofibroblasts is associated with an increase in mitochondrial content and function when compared to naive fibroblasts. Methods Cultured NIH/3T3 mouse fibroblasts treated with TGF-β1, a profibrotic cytokine, or vehicle were assessed for transformation to myofibroblasts (appearance of α-smooth muscle actin [α-SMA] stress fibers) and associated changes in mitochondrial content and functions using laser confocal microscopy, Seahorse respirometry, multi-well plate reader and biochemical protocols. Expression of mitochondrial-specific proteins was determined using western blotting, and the mitochondrial DNA quantified using Mitochondrial DNA isolation kit. Results Treatment with TGF-β1 (5 ng/mL) induced transformation of naive fibroblasts into myofibroblasts with a threefold increase in the expression of α-SMA (6.85 ± 0.27 RU) compared to cells not treated with TGF-β1 (2.52 ± 0.11 RU). TGF-β1 exposure increased the number of mitochondria in the cells, as monitored by membrane potential sensitive dye tetramethylrhodamine, and expression of mitochondria-specific proteins; voltage-dependent anion channels (0.54 ± 0.05 vs. 0.23 ± 0.05 RU) and adenine nucleotide transporter (0.61 ± 0.11 vs. 0.22 ± 0.05 RU), as well as mitochondrial DNA content (530 ± 12 μg DNA/106 cells vs. 307 ± 9 μg DNA/106 cells in control). TGF-β1 treatment was associated with an increase in mitochondrial function with a twofold increase in baseline oxygen consumption rate (2.25 ± 0.03 vs. 1.13 ± 0.1 nmol O2/min/106 cells) and FCCP-induced mitochondrial respiration (2.87 ± 0.03 vs. 1.46 ± 0.15 nmol O2/min/106 cells

The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum retain functionally overlapping mitochondria from two evolutionarily distinct lineages

PubMed Central

Imanian, Behzad; Keeling, Patrick J

2007-01-01

Background The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum are distinguished by the presence of a tertiary plastid derived from a diatom endosymbiont. The diatom is fully integrated with the host cell cycle and is so altered in structure as to be difficult to recognize it as a diatom, and yet it retains a number of features normally lost in tertiary and secondary endosymbionts, most notably mitochondria. The dinoflagellate host is also reported to retain mitochondrion-like structures, making these cells unique in retaining two evolutionarily distinct mitochondria. This redundancy raises the question of whether the organelles share any functions in common or have distributed functions between them. Results We show that both host and endosymbiont mitochondrial genomes encode genes for electron transport proteins. We have characterized cytochrome c oxidase 1 (cox1), cytochrome oxidase 2 (cox2), cytochrome oxidase 3 (cox3), cytochrome b (cob), and large subunit of ribosomal RNA (LSUrRNA) of endosymbiont mitochondrial ancestry, and cox1 and cob of host mitochondrial ancestry. We show that all genes are transcribed and that those ascribed to the host mitochondrial genome are extensively edited at the RNA level, as expected for a dinoflagellate mitochondrion-encoded gene. We also found evidence for extensive recombination in the host mitochondrial genes and that recombination products are also transcribed, as expected for a dinoflagellate. Conclusion Durinskia baltica and K. foliaceum retain two mitochondria from evolutionarily distinct lineages, and the functions of these organelles are at least partially overlapping, since both express genes for proteins in electron transport. PMID:17892581

MFN1 deacetylation activates adaptive mitochondrial fusion and protects metabolically challenged mitochondria.

PubMed

Lee, Joo-Yong; Kapur, Meghan; Li, Ming; Choi, Moon-Chang; Choi, Sujin; Kim, Hak-June; Kim, Inhye; Lee, Eunji; Taylor, J Paul; Yao, Tso-Pang

2014-11-15

Fasting and glucose shortage activate a metabolic switch that shifts more energy production to mitochondria. This metabolic adaptation ensures energy supply, but also elevates the risk of mitochondrial oxidative damage. Here, we present evidence that metabolically challenged mitochondria undergo active fusion to suppress oxidative stress. In response to glucose starvation, mitofusin 1 (MFN1) becomes associated with the protein deacetylase HDAC6. This interaction leads to MFN1 deacetylation and activation, promoting mitochondrial fusion. Deficiency in HDAC6 or MFN1 prevents mitochondrial fusion induced by glucose deprivation. Unexpectedly, failure to undergo fusion does not acutely affect mitochondrial adaptive energy production; instead, it causes excessive production of mitochondrial reactive oxygen species and oxidative damage, a defect suppressed by an acetylation-resistant MFN1 mutant. In mice subjected to fasting, skeletal muscle mitochondria undergo dramatic fusion. Remarkably, fasting-induced mitochondrial fusion is abrogated in HDAC6-knockout mice, resulting in extensive mitochondrial degeneration. These findings show that adaptive mitochondrial fusion protects metabolically challenged mitochondria. © 2014. Published by The Company of Biologists Ltd.

Mitochondrial DNA Variation and the Evolution of Robertsonian Chromosomal Races of House Mice, Mus Domesticus

PubMed Central

Nachman, M. W.; Boyer, S. N.; Searle, J. B.; Aquadro, C. F.

1994-01-01

The house mouse, Mus domesticus, includes many distinct Robertsonian (Rb) chromosomal races with diploid numbers from 2n = 22 to 2n = 38. Although these races are highly differentiated karyotypically, they are otherwise indistinguishable from standard karyotype (i.e., 2n = 40) mice, and consequently their evolutionary histories are not well understood. We have examined mitochondrial DNA (mtDNA) sequence variation from the control region and the ND3 gene region among 56 M. domesticus from Western Europe, including 15 Rb populations and 13 standard karyotype populations, and two individuals of the sister species, Mus musculus. mtDNA exhibited an average sequence divergence of 0.84% within M. domesticus and 3.4% between M. domesticus and M. musculus. The transition/transversion bias for the regions sequenced is 5.7:1, and the overall rate of sequence evolution is approximately 10% divergence per million years. The amount of mtDNA variation was as great among different Rb races as among different populations of standard karyotype mice, suggesting that different Rb races do not derive from a single recent maternal lineage. Phylogenetic analysis of the mtDNA sequences resulted in a parsimony tree which contained six major clades. Each of these clades contained both Rb and standard karyotype mice, consistent with the hypothesis that Rb races have arisen independently multiple times. Discordance between phylogeny and geography was attributable to ancestral polymorphism as a consequence of the recent colonization of Western Europe by mice. Two major mtDNA lineages were geographically localized and contained both Rb and standard karyotype mice. The age of these lineages suggests that mice have moved into Europe only within the last 10,000 years and that Rb populations in different geographic regions arose during this time. PMID:8005418

Decrypting the Mitochondrial Gene Pool of Modern Panamanians

PubMed Central

Angerhofer, Norman; Ekins, Jayne E.; Olivieri, Anna; Woodward, Scott R.; Pascale, Juan Miguel; Cooke, Richard; Motta, Jorge; Achilli, Alessandro

2012-01-01

The Isthmus of Panama–the narrow neck of land connecting the northern and southern American landmasses–was an obligatory corridor for the Paleo-Indians as they moved into South America. Archaeological evidence suggests an unbroken link between modern natives and their Paleo-Indian ancestors in some areas of Panama, even if the surviving indigenous groups account for only 12.3% of the total population. To evaluate if modern Panamanians have retained a larger fraction of the native pre-Columbian gene pool in their maternally-inherited mitochondrial genome, DNA samples and historical records were collected from more than 1500 volunteer participants living in the nine provinces and four indigenous territories of the Republic. Due to recent gene-flow, we detected ∼14% African mitochondrial lineages, confirming the demographic impact of the Atlantic slave trade and subsequent African immigration into Panama from Caribbean islands, and a small European (∼2%) component, indicating only a minor influence of colonialism on the maternal side. The majority (∼83%) of Panamanian mtDNAs clustered into native pan-American lineages, mostly represented by haplogroup A2 (51%). These findings reveal an overwhelming native maternal legacy in today's Panama, which is in contrast with the overall concept of personal identity shared by many Panamanians. Moreover, the A2 sub-clades A2ad and A2af (with the previously named 6 bp Huetar deletion), when analyzed at the maximum level of resolution (26 entire mitochondrial genomes), confirm the major role of the Pacific coastal path in the peopling of North, Central and South America, and testify to the antiquity of native mitochondrial genomes in Panama. PMID:22675545

Negative regulation of miRNA-9 on oligodendrocyte lineage gene 1 during hypoxic-ischemic brain damage.

PubMed

Yang, Lijun; Cui, Hong; Cao, Ting

2014-03-01

Oligodendrocyte lineage gene 1 plays a key role in hypoxic-ischemic brain damage and myelin repair. miRNA-9 is involved in the occurrence of many related neurological disorders. Bioinformatics analysis demonstrated that miRNA-9 complementarily, but incompletely, bound oligodendrocyte lineage gene 1, but whether miRNA-9 regulates oligodendrocyte lineage gene 1 remains poorly understood. Whole brain slices of 3-day-old Sprague-Dawley rats were cultured and divided into four groups: control group; oxygen-glucose deprivation group (treatment with 8% O2 + 92% N2 and sugar-free medium for 60 minutes); transfection control group (after oxygen and glucose deprivation for 60 minutes, transfected with control plasmid) and miRNA-9 transfection group (after oxygen and glucose deprivation for 60 minutes, transfected with miRNA-9 plasmid). From the third day of transfection, and with increasing culture days, oligodendrocyte lineage gene 1 expression increased in each group, peaked at 14 days, and then decreased at 21 days. Real-time quantitative PCR results, however, demonstrated that oligodendrocyte lineage gene 1 expression was lower in the miRNA-9 transfection group than that in the transfection control group at 1, 3, 7, 14, 21 and 28 days after transfection. Results suggested that miRNA-9 possibly negatively regulated oligodendrocyte lineage gene 1 in brain tissues during hypoxic-ischemic brain damage.

The viability and protein expression of Beijing/W lineage Mycobacterium tuberculosis circulating in Xinjiang, China.

PubMed

Li, Feng; Li, Hua; Zuo, Wei-Ze; Mi, Ligu; Wang, Xian; Wang, Yuanzhi; Wang, Hong; Shen, Aiping; Cao, Shuaili; Yuan, Li

2015-05-01

Beijing/W lineage strains of Mycobacterium tuberculosis spread faster than other strains, tend to be more virulent and frequently associated with drug resistance. In this study, to distinguish the characteristics of Beijing/W lineage and non-Beijing/W lineage M. tuberculosis, we assessed the growth between the two groups under conditions of hypoxia, nutrient starvation, and intracellular growth in murine macrophages. We also examined the DNA, RNA, and protein levels of 5 major M. tuberculosis proteins, including HspX, Hsp65, 38 kDa, Ag85B, and MPT64 of the different types of strains by sequencing, quantitative RT-PCR, and Western blotting. The results showed that Beijing/W and non-Beijing/W lineage strains of M. tuberculosis have similar viability in ex vivo culture but differ in their ability to survive within macrophages, and the intracellular viability of the Beijing/W lineage strains was significantly more than the viability of the non-Beijing/W lineage strains at 2, 3, and 5 days after infection (P < 0.05). Psts1 and fbpB were expressed at statistically lower levels in Beijing/W lineage strains in their mRNA expression levels (P < 0.05). The expression of their corresponding 38 kDa and Ag85B was lower in the Beijing/W lineage strains than the non-Beijing/W lineage strains (P < 0.05). The expression of HspX and Hsp65 was higher in the Beijing/W lineage strains in their protein expression levels at 24 h after infection of RAW264.7 macrophages (P < 0.05). In conclusion, the increased viability of the Beijing/W lineage strains might be related to the expression levels of these proteins.

Evidence for horizontal transfer of mitochondrial DNA to the plastid genome in a bamboo genus.

PubMed

Ma, Peng-Fei; Zhang, Yu-Xiao; Guo, Zhen-Hua; Li, De-Zhu

2015-06-23

In flowering plants, three genomes (nuclear, mitochondrial, and plastid) coexist and intracellular horizontal transfer of DNA is prevalent, especially from the plastid to the mitochondrion genome. However, the plastid genomes are generally conserved in evolution and have long been considered immune to foreign DNA. Recently, the opposite direction of DNA transfer from the mitochondrial to the plastid genome has been reported in two eudicot lineages. Here we sequenced 6 plastid genomes of bamboos, three of which are neotropical woody species and three are herbaceous ones. Several unusual features were found, including the duplication of trnT-GGU and loss of one copy of rps19 due to contraction of inverted repeats (IRs). The most intriguing was the ~2.7 kb insertion in the plastid IR regions in the three herbaceous bamboos. Furthermore, the insertion was documented to be horizontally transferred from the mitochondrial to the plastid genome. Our study provided evidence of the mitochondrial-to-plastid DNA transfer in the monocots, demonstrating again that this rare event does occur in other angiosperm lineages. However, the mechanism underlying the transfer remains obscure, and more studies in other plants may elucidate it in the future.

Msh1p counteracts oxidative lesion-induced instability of mtDNA and stimulates mitochondrial recombination in Saccharomyces cerevisiae.

PubMed

Kaniak, Aneta; Dzierzbicki, Piotr; Rogowska, Agata T; Malc, Ewa; Fikus, Marta; Ciesla, Zygmunt

2009-03-01

The proximity of the mitochondrial genome to the respiratory chain, a major source of ROS (radical oxygen species), makes mtDNA more vulnerable to oxidative damage than nuclear DNA. Mitochondrial BER (base excision repair) is generally considered to be the main pathway involved in the prevention of oxidative lesion-induced mutations in mtDNA. However, we previously demonstrated that the increased frequency of mitochondrial Oli(r) mutants in an ogg1Delta strain, lacking the activity of a crucial mtBER glycosylase, is reduced in the presence of plasmids encoding Msh1p, the mitochondrial homologue of the bacterial mismatch protein MutS. This finding suggested that Msh1p might be involved in the prevention of mitochondrial mutagenesis induced by oxidative stress. Here we show that a double mutant carrying the msh1-R813W allele, encoding a variant of the protein defective in the ATP hydrolysis activity, combined with deletion of SOD2, encoding the mitochondrial superoxide dismutase, displays a synergistic effect on the frequency of Oli(r) mutants, indicating that Msh1p prevents generation of oxidative lesion-induced mitochondrial mutations. We also show that double mutants carrying the msh1-R813W allele, combined with deletion of either OGG1 or APN1, the latter resulting in deficiency of the Apn1 endonuclease, exhibit a synergistic effect on the frequency of respiration-defective mutants having gross rearrangements of the mitochondrial genome. This suggests that Msh1p, Ogg1p and Apn1p play overlapping functions in maintaining the stability of mtDNA. In addition, we demonstrate, using a novel ARG8(m) recombination assay, that a surplus of Msh1p results in enhanced mitochondrial recombination. Interestingly, the mutant forms of the protein, msh1p-R813W and msh1p-G776D, fail to stimulate recombination. We postulate that the Msh1p-enhanced homologous recombination may play an important role in the prevention of oxidative lesion-induced rearrangements of the mitochondrial

Inter- and intraspecific mitochondrial DNA variation in North American bears (Ursus)

USGS Publications Warehouse

Cronin, Matthew A.; Amstrup, Steven C.; Garner, Gerald W.; Vyse, Ernest R.

1991-01-01

We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.

Yeast mitochondrial glutathione is an essential antioxidant with mitochondrial thioredoxin providing a back-up system

PubMed Central

Gostimskaya, Irina; Grant, Chris M.

2016-01-01

Glutathione is an abundant, low-molecular-weight tripeptide whose biological importance is dependent upon its redox-active free sulphydryl moiety. Its role as the main determinant of thiol-redox control has been challenged such that it has been proposed to play a crucial role in iron–sulphur clusters maturation, and only a minor role in thiol redox regulation, predominantly as a back-up system for the cytoplasmic thioredoxin system. Here, we have tested the importance of mitochondrial glutathione in thiol-redox regulation. Glutathione reductase (Glr1) is an oxidoreductase which converts oxidized glutathione to its reduced form. Yeast Glr1 localizes to both the cytosol and mitochondria and we have used a Glr1M1L mutant that is constitutively localized to the cytosol to test the requirement for mitochondrial Glr1. We show that the loss of mitochondrial Glr1 specifically accounts for oxidant sensitivity of a glr1 mutant. Loss of mitochondrial Glr1 does not influence iron–sulphur cluster maturation and we have used targeted roGFP2 fluorescent probes to show that oxidant sensitivity is linked to an altered redox environment. Our data indicate mitochondrial glutathione is crucial for mitochondrial thiol-redox regulation, and the mitochondrial thioredoxin system provides a back-up system, but cannot bear the redox load of the mitochondria on its own. PMID:26898146

Overexpression of mitochondrial sirtuins alters glycolysis and mitochondrial function in HEK293 cells.

PubMed

de Moura, Michelle Barbi; Uppala, Radha; Zhang, Yuxun; Van Houten, Bennett; Goetzman, Eric S

2014-01-01

SIRT3, SIRT4, and SIRT5 are mitochondrial deacylases that impact multiple facets of energy metabolism and mitochondrial function. SIRT3 activates several mitochondrial enzymes, SIRT4 represses its targets, and SIRT5 has been shown to both activate and repress mitochondrial enzymes. To gain insight into the relative effects of the mitochondrial sirtuins in governing mitochondrial energy metabolism, SIRT3, SIRT4, and SIRT5 overexpressing HEK293 cells were directly compared. When grown under standard cell culture conditions (25 mM glucose) all three sirtuins induced increases in mitochondrial respiration, glycolysis, and glucose oxidation, but with no change in growth rate or in steady-state ATP concentration. Increased proton leak, as evidenced by oxygen consumption in the presence of oligomycin, appeared to explain much of the increase in basal oxygen utilization. Growth in 5 mM glucose normalized the elevations in basal oxygen consumption, proton leak, and glycolysis in all sirtuin over-expressing cells. While the above effects were common to all three mitochondrial sirtuins, some differences between the SIRT3, SIRT4, and SIRT5 expressing cells were noted. Only SIRT3 overexpression affected fatty acid metabolism, and only SIRT4 overexpression altered superoxide levels and mitochondrial membrane potential. We conclude that all three mitochondrial sirtuins can promote increased mitochondrial respiration and cellular metabolism. SIRT3, SIRT4, and SIRT5 appear to respond to excess glucose by inducing a coordinated increase of glycolysis and respiration, with the excess energy dissipated via proton leak.

Complex IV Deficient Surf1−/− Mice Initiate Mitochondrial Stress Responses

PubMed Central

Pulliam, Daniel A.; Deepa, Sathyaseelan S.; Liu, Yuhong; Hill, Shauna; Lin, Ai-Ling; Bhattacharya, Arunabh; Shi, Yun; Sloane, Lauren; Viscomi, Carlo; Zeviani, Massimo; Van Remmen, Holly

2014-01-01

Summary Mutations in SURF1 cytochrome c oxidase (COX) assembly protein are associated with Leigh’s syndrome, a human mitochondrial disorder that manifests as severe mitochondrial phenotypes and early lethality. In contrast, mice lacking the Surf1 protein (Surf1−/−) are viable and were previously shown to have enhanced longevity and a greater than 50% reduction in COX activity. We measured mitochondrial function in heart and skeletal muscle, and despite the significant reduction in COX activity, we found little or no difference in reactive oxygen species (ROS) generation, membrane potential, ATP production or respiration in isolated mitochondria from Surf1−/− mice compared to wild-type. However, blood lactate levels are elevated and Surf1−/− mice have reduced running endurance, suggesting compromised mitochondrial energy metabolism in vivo. Decreased COX activity in Surf1−/− mice is associated with increased markers of mitochondrial biogenesis (PGC-1α and VDAC) in both heart and skeletal muscle. While mitochondrial biogenesis is a common response in the two tissues, skeletal muscle have an up-regulation of the mitochondrial unfolded protein response (UPRMT) and heart exhibits induction of the Nrf2 antioxidant response pathway. These data are the first to report induction of the UPRMT in a mammalian model of diminished COX activity. In addition our results suggest that impaired mitochondrial function can lead to induction of mitochondrial stress pathways to confer protective effects on cellular homeostasis. Loss of complex IV assembly factor Surf1 in mice results in compensatory responses including mitochondrial biogenesis, the nrf2 pathway and the mitochondrial unfolded protein response. This compensatory response may contribute to the lack of deleterious phenotypes under basal conditions. PMID:24911525

First report of multiple lineages of dengue viruses type 1 in Rio de Janeiro, Brazil.

PubMed

dos Santos, Flavia B; Nogueira, Fernanda B; Castro, Márcia G; Nunes, Priscila Cg; de Filippis, Ana Maria B; Faria, Nieli Rc; Simões, Jaqueline Bs; Sampaio, Simone A; Santos, Clarice R; Nogueira, Rita Maria R

2011-08-03

In Brazil dengue has been a major public health problem since DENV-1 introduction and spread in 1986. After a low or silent co-circulation, DENV-1 re-emerged in 2009 causing a major epidemic in the country in 2010 and 2011. In this study, the phylogeny of DENV-1 strains isolated in RJ after its first introduction in 1986 and after its emergence in 2009 and 2010 was performed in order to document possible evolutionary patterns or introductions in a re-emergent virus. The analysis of the E gene sequences demonstrated that DENV-1 isolated during 2009/2010 still belong to genotype V (Americas/Africa) but grouping in a distinct clade (lineage II) of that represented by earlier DENV-1 (lineage I). However, strains isolated in 2011 grouped together forming another distinct clade (lineage III). The monitoring of DENV is important to observe the spread of potentially virulent strains as well to evaluate its impact over the population during an outbreak. Whether explosive epidemics reported in Brazil caused mainly by DENV-1 was due to lineage replacement, or due the population susceptibility to this serotype which has not circulated for almost a decade or even due to the occurrence of secondary infections in a hyperendemic country, is not clear. This is the first report of multiple lineages of DENV-1 detected in Brazil.

The origin of widespread species in a poor dispersing lineage (diving beetle genus Deronectes).

PubMed

García-Vázquez, David; Ribera, Ignacio

2016-01-01

In most lineages, most species have restricted geographic ranges, with only few reaching widespread distributions. How these widespread species reached their current ranges is an intriguing biogeographic and evolutionary question, especially in groups known to be poor dispersers. We reconstructed the biogeographic and temporal origin of the widespread species in a lineage with particularly poor dispersal capabilities, the diving beetle genus Deronectes (Dytiscidae). Most of the ca. 60 described species of Deronectes have narrow ranges in the Mediterranean area, with only four species with widespread European distributions. We sequenced four mitochondrial and two nuclear genes of 297 specimens of 109 different populations covering the entire distribution of the four lineages of Deronectes , including widespread species. Using Bayesian probabilities with an a priori evolutionary rate, we performed (1) a global phylogeny/phylogeography to estimate the relationships of the main lineages within each group and root them, and (2) demographic analyses of the best population coalescent model for each species group, including a reconstruction of the geographical history estimated from the distribution of the sampled localities. We also selected 56 specimens to test for the presence of Wolbachia , a maternally transmitted parasite that can alter the patterns of mtDNA variability. All species of the four studied groups originated in the southern Mediterranean peninsulas and were estimated to be of Pleistocene origin. In three of the four widespread species, the central and northern European populations were nested within those in the northern areas of the Anatolian, Balkan and Iberian peninsulas respectively, suggesting a range expansion at the edge of the southern refugia. In the Mediterranean peninsulas the widespread European species were replaced by vicariant taxa of recent origin. The fourth species ( D. moestus ) was proven to be a composite of unrecognised lineages with

The origin of widespread species in a poor dispersing lineage (diving beetle genus Deronectes)

PubMed Central

García-Vázquez, David

2016-01-01

In most lineages, most species have restricted geographic ranges, with only few reaching widespread distributions. How these widespread species reached their current ranges is an intriguing biogeographic and evolutionary question, especially in groups known to be poor dispersers. We reconstructed the biogeographic and temporal origin of the widespread species in a lineage with particularly poor dispersal capabilities, the diving beetle genus Deronectes (Dytiscidae). Most of the ca. 60 described species of Deronectes have narrow ranges in the Mediterranean area, with only four species with widespread European distributions. We sequenced four mitochondrial and two nuclear genes of 297 specimens of 109 different populations covering the entire distribution of the four lineages of Deronectes, including widespread species. Using Bayesian probabilities with an a priori evolutionary rate, we performed (1) a global phylogeny/phylogeography to estimate the relationships of the main lineages within each group and root them, and (2) demographic analyses of the best population coalescent model for each species group, including a reconstruction of the geographical history estimated from the distribution of the sampled localities. We also selected 56 specimens to test for the presence of Wolbachia, a maternally transmitted parasite that can alter the patterns of mtDNA variability. All species of the four studied groups originated in the southern Mediterranean peninsulas and were estimated to be of Pleistocene origin. In three of the four widespread species, the central and northern European populations were nested within those in the northern areas of the Anatolian, Balkan and Iberian peninsulas respectively, suggesting a range expansion at the edge of the southern refugia. In the Mediterranean peninsulas the widespread European species were replaced by vicariant taxa of recent origin. The fourth species (D. moestus) was proven to be a composite of unrecognised lineages with

Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics

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

Miyamoto, Yuki; Eguchi, Takahiro; Kawahara, Kazuko

Myelin-forming glial cells undergo dynamic morphological changes in order to produce mature myelin sheaths with multiple layers. In the central nervous system (CNS), oligodendrocytes differentiate to insulate neuronal axons with myelin sheaths. Myelin sheaths play a key role in homeostasis of the nervous system, but their related disorders lead not only to dismyelination and repeated demyelination but also to severe neuropathies. Hereditary hypomyelinating leukodystrophies (HLDs) are a group of such diseases affecting oligodendrocytes and are often caused by missense mutations of the respective responsible genes. Despite increasing identification of gene mutations through advanced nucleotide sequencing technology, studies on the relationshipsmore » between gene mutations and their effects on cellular and subcellular aberrance have not followed at the same rapid pace. In this study, we report that an HLD4-associated (Asp-29-to-Gly) mutant of mitochondrial heat shock 60-kDa protein 1 (HSPD1) causes short-length morphologies and increases the numbers of mitochondria due to their aberrant fission and fusion cycles. In experiments using a fluorescent dye probe, this mutation decreases the mitochondrial membrane potential. Also, mitochondria accumulate in perinuclear regions. HLD4-associated HSPD1 mutant blunts mitochondrial dynamics, probably resulting in oligodendrocyte malfunction. This study constitutes a first finding concerning the relationship between disease-associated HSPD1 mutation and mitochondrial dynamics, which may be similar to the relationship between another disease-associated HSPD1 mutation (MitCHAP-60 disease) and aberrant mitochondrial dynamics. - Highlights: • The HLD4 mutant of HSPD1 decreases mitochondrial fission frequency. • The HLD4 mutant decreases mitochondrial fusion frequency. • Mitochondria harboring the HLD4 mutant exhibit slow motility. • The HLD4 mutant of HSPD1 decreases mitochondrial membrane potential. • HLD4-related

Mitochondrial modulators in experimental Huntington's disease: reversal of mitochondrial dysfunctions and cognitive deficits.

PubMed

Mehrotra, Arpit; Kanwal, Abhinav; Banerjee, Sanjay Kumar; Sandhir, Rajat

2015-06-01

Huntington's disease (HD) is a chronic neurodegenerative condition involving impaired mitochondrial functions. The present study evaluates the therapeutic potential of combined administration of mitochondrial modulators: alpha-lipoic acid and acetyl-l-carnitine on mitochondrial dysfunctions in 3-NP-induced HD. Our results reveal 3-NP administration resulted in compromise of mitochondrial functions in terms of: (1) impaired activity of mitochondrial respiratory chain enzymes, altered cytochrome levels, reduced histochemical staining of complex-II and IV, reduced in-gel activity of complex-I to V, and reduced mRNA expression of respiratory chain complexes; (2) enhanced mitochondrial oxidative stress indicated by increased malondialdehyde, protein carbonyls, reactive oxygen species and nitrite levels, along with decreased Mn-superoxide dismutase and catalase activity; (3) mitochondrial structural changes measured by mitochondrial swelling, reduced mitochondrial membrane potential and ultra-structure changes; (4) increased cytosolic cytochrome c levels, caspase-3 and -9 activity along with altered expression of apoptotic proteins (AIF, Bim, Bad, and Bax); and (5) impaired cognitive functions assessed using Morris water maze and Y-maze. Combination of mitochondrial modulators (alpha-lipoic acid + acetyl-l-carnitine) on the other hand ameliorated 3-NP-induced mitochondrial dysfunctions, oxidative stress, histologic alterations, and behavioral deficits, suggesting their therapeutic efficacy in the management of HD. Copyright © 2015 Elsevier Inc. All rights reserved.

PGC-1α Regulation of Mitochondrial Degeneration in Experimental Diabetic Neuropathy

PubMed Central

Choi, Joungil; Chandrasekaran, Krish; Inoue, Tatsuya; Muragundla, Anjaneyulu; Russell, James W.

2014-01-01

Mitochondrial degeneration is considered to play an important role in the development of diabetic peripheral neuropathy in humans. Mitochondrial degeneration and the corresponding protein regulation associated with the degeneration were studied in an animal model of diabetic neuropathy. PGC-1α and its-regulated transcription factors including TFAM and NRF1, which are master regulators of mitochondrial biogenesis, are significantly downregulated in streptozotocin diabetic dorsal root ganglion (DRG) neurons. Diabetic mice develop peripheral neuropathy, loss of mitochondria, decreased mitochondrial DNA content and increased protein oxidation. Importantly, this phenotype is exacerbated in PGC-1α (−/−) diabetic mice, which develop a more severe neuropathy with reduced mitochondrial DNA and a further increase in protein oxidation. PGC-1α (−/−) diabetic mice develop an increase in total cholesterol and triglycerides, and a decrease in TFAM and NRF1 protein levels. Loss of PGC-1α causes severe mitochondrial degeneration with vacuolization in DRG neurons, coupled with reduced state 3 and 4 respiration, reduced expression of oxidative stress response genes and an increase in protein oxidation. In contrast, overexpression of PGC-1α in cultured adult mouse neurons prevents oxidative stress associated with increased glucose levels. The study provides new insights into the role of PGC-1α in mitochondrial regeneration in peripheral neurons and suggests that therapeutic modulation of PGC-1α function may be an attractive approach for treatment of diabetic neuropathy. PMID:24423644

Mitochondrial and performance adaptations to exercise training in mice lacking skeletal muscle LKB1

PubMed Central

Tanner, Colby B.; Madsen, Steven R.; Hallowell, David M.; Goring, Darren M. J.; Moore, Timothy M.; Hardman, Shalene E.; Heninger, Megan R.; Atwood, Daniel R.

2013-01-01

LKB1 and its downstream targets of the AMP-activated protein kinase family are important regulators of many aspects of skeletal muscle cell function, including control of mitochondrial content and capillarity. LKB1 deficiency in skeletal and cardiac muscle (mLKB1-KO) greatly impairs exercise capacity. However, cardiac dysfunction in that genetic model prevents a clear assessment of the role of skeletal muscle LKB1 in the observed effects. Our purposes here were to determine whether skeletal muscle-specific knockout of LKB1 (skmLKB1-KO) decreases exercise capacity and mitochondrial protein content, impairs accretion of mitochondrial proteins after exercise training, and attenuates improvement in running performance after exercise training. We found that treadmill and voluntary wheel running capacity was reduced in skmLKB1-KO vs. control (CON) mice. Citrate synthase activity, succinate dehydrogenase activity, and pyruvate dehydrogenase kinase content were lower in KO vs. CON muscles. Three weeks of treadmill training resulted in significantly increased treadmill running performance in both CON and skmLKB1-KO mice. Citrate synthase activity increased significantly with training in both genotypes, but protein content and activity for components of the mitochondrial electron transport chain increased only in CON mice. Capillarity and VEGF protein was lower in skmLKB1-KO vs. CON muscles, but VEGF increased with training only in skmLKB1-KO. Three hours after an acute bout of muscle contractions, PGC-1α, cytochrome c, and VEGF gene expression all increased in CON but not skmLKB1-KO muscles. Our findings indicate that skeletal muscle LKB1 is required for accretion of some mitochondrial proteins but not for early exercise capacity improvements with exercise training. PMID:23982155

Biome specificity of distinct genetic lineages within the four-striped mouse Rhabdomys pumilio (Rodentia: Muridae) from southern Africa with implications for taxonomy.

PubMed

du Toit, Nina; van Vuuren, Bettine Jansen; Matthee, Sonja; Matthee, Conrad A

2012-10-01

Within southern Africa, a link between past climatic changes and faunal diversification has been hypothesized for a diversity of taxa. To test the hypothesis that evolutionary divergences may be correlated to vegetation changes (induced by changes in climate), we selected the widely distributed four-striped mouse, Rhabdomys, as a model. Two species are currently recognized, the mesic-adapted R. dilectus and arid-adapted R. pumilio. However, the morphology-based taxonomy and the distribution boundaries of previously described subspecies remain poorly defined. The current study, which spans seven biomes, focuses on the spatial genetic structure of the arid-adapted R. pumilio (521 specimens from 31 localities), but also includes limited sampling of the mesic-adapted R. dilectus (33 specimens from 10 localities) to act as a reference for interspecific variation within the genus. The mitochondrial COI gene and four nuclear introns (Eef1a1, MGF, SPTBN1, Bfib7) were used for the construction of gene trees. Mitochondrial DNA analyses indicate that Rhabdomys consists of four reciprocally monophyletic, geographically structured clades, with three distinct lineages present within the arid-adapted R. pumilio. These monophyletic lineages differ by at least 7.9% (±0.3) and these results are partly confirmed by a multilocus network of the combined nuclear intron dataset. Ecological niche modeling in MaxEnt supports a strong correlation between regional biomes and the distribution of distinct evolutionary lineages of Rhabdomys. A Bayesian relaxed molecular clock suggests that the geographic clades diverged between 3.09 and 4.30Ma, supporting the hypothesis that the radiation within the genus coincides with paleoclimatic changes (and the establishment of the biomes) characterizing the Miocene-Pliocene boundary. Marked genetic divergence at the mitochondrial DNA level, coupled with strong nuclear and mtDNA signals of non-monophyly of R. pumilio, support the notion that a taxonomic

Enhanced nasopharyngeal infection and shedding associated with an epidemic lineage of emm3 group A Streptococcus.

PubMed

Afshar, Baharak; Turner, Claire E; Lamagni, Theresa L; Smith, Ken C; Al-Shahib, Ali; Underwood, Anthony; Holden, Matthew T G; Efstratiou, Androulla; Sriskandan, Shiranee

2017-10-03

A group A Streptococcus (GAS) lineage of genotype emm3, sequence type 15 (ST15) was associated with a 6 month upsurge in invasive GAS disease in the UK. The epidemic lineage (Lineage C) had lost 2 typical emm3 prophages, Φ315.1 and Φ315.2 associated with the superantigen ssa, but gained a different prophage (ΦUK-M3.1) associated with a different superantigen, speC and a DNAse spd1. The presence of speC and spd1 in Lineage C ST15 strains enhanced both in vitro mitogenic and DNase activities over non-Lineage C ST15 strains. Invasive disease models in Galleria mellonella and SPEC-sensitive transgenic mice, revealed no difference in overall invasiveness of Lineage C ST15 strains compared with non-Lineage C ST15 strains, consistent with clinical and epidemiological analysis. Lineage C strains did however markedly prolong murine nasal infection with enhanced nasal and airborne shedding compared with non-Lineage C strains. Deletion of speC or spd1 in 2 Lineage C strains identified a possible role for spd1 in airborne shedding from the murine nasopharynx. Nasopharyngeal infection and shedding of Lineage C strains was enhanced compared with non-Lineage C strains and this was, in part, mediated by the gain of the DNase spd1 through prophage acquisition.

Sudden adult death syndrome in m.3243A>G-related mitochondrial disease: an unrecognized clinical entity in young, asymptomatic adults.

PubMed

Ng, Yi Shiau; Grady, John P; Lax, Nichola Z; Bourke, John P; Alston, Charlotte L; Hardy, Steven A; Falkous, Gavin; Schaefer, Andrew G; Radunovic, Aleksandar; Mohiddin, Saidi A; Ralph, Matilda; Alhakim, Ali; Taylor, Robert W; McFarland, Robert; Turnbull, Douglass M; Gorman, Gráinne S

2016-08-21

To provide insight into the mechanism of sudden adult death syndrome (SADS) and to give new clinical guidelines for the cardiac management of patients with the most common mitochondrial DNA mutation, m.3243A>G. These studies were initiated after two young, asymptomatic adults harbouring the m.3243A>G mutation died suddenly and unexpectedly. The m.3243A>G mutation is present in ∼1 in 400 of the population, although the recognized incidence of mitochondrial DNA (mtDNA) disease is ∼1 in 5000. Pathological studies including histochemistry and molecular genetic analyses performed on various post-mortem samples including cardiac tissues (atrium and ventricles) showed marked respiratory chain deficiency and high levels of the m.3243A>G mutation. Systematic review of cause of death in our m.3243A>G patient cohort showed the person-time incidence rate of sudden adult death is 2.4 per 1000 person-years. A further six cases of sudden death among extended family members have been identified from interrogation of family pedigrees. Our findings suggest that SADS is an important cause of death in patients with m.3243A>G and likely to be due to widespread respiratory chain deficiency in cardiac muscle. The involvement of asymptomatic relatives highlights the importance of family tracing in patients with m.3243A>G and the need for specific cardiac arrhythmia surveillance in the management of this common genetic disease. In addition, these findings have prompted the derivation of cardiac guidelines specific to patients with m.3243A>G-related mitochondrial disease. Finally, due to the prevalence of this mtDNA point mutation, we recommend inclusion of testing for m.3243A>G mutations in the genetic autopsy of all unexplained cases of SADS. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

Alcohol alters hepatic FoxO1, p53, and mitochondrial SIRT5 deacetylation function

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

Lieber, Charles S.; Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029; Leo, Maria Anna

2008-08-22

Chronic alcohol consumption affects the gene expression of a NAD-dependent deacetylase Sirtuis 1 (SIRT1) and the peroxisome proliferator-activated receptor-{gamma} coactivator1{alpha} (PGC-1{alpha}). Our aim was to verify that it also alters the forkhead (FoxO1) and p53 transcription factor proteins, critical in the hepatic response to oxidative stress and regulated by SIRT1 through its deacetylating capacity. Accordingly, rats were pair-fed the Lieber-DeCarli alcohol-containing liquid diets for 28 days. Alcohol increased hepatic mRNA expression of FoxO1 (p = 0.003) and p53 (p = 0.001) while corresponding protein levels remained unchanged. However phospho-FoxO1 and phospho-Akt (protein kinase) were both decreased by alcohol consumption (pmore » = 0.04 and p = 0.02, respectively) while hepatic p53 was found hyperacetylated (p = 0.017). Furthermore, mitochondrial SIRT5 was reduced (p = 0.0025), and PGC-1{alpha} hyperacetylated (p = 0.027), establishing their role in protein modification. Thus, alcohol consumption disrupts nuclear-mitochondrial interactions by post-translation protein modifications, which contribute to alteration of mitochondrial biogenesis through the newly discovered reduction of SIRT5.« less

Relationship between PPARα mRNA expression and mitochondrial respiratory function and ultrastructure of the skeletal muscle of patients with COPD.

PubMed

Zhang, Jian-Qing; Long, Xiang-Yu; Xie, Yu; Zhao, Zhi-Huan; Fang, Li-Zhou; Liu, Ling; Fu, Wei-Ping; Shu, Jing-Kui; Wu, Jiang-Hai; Dai, Lu-Ming

2017-11-02

Peripheral muscle dysfunction is an important complication in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to explore the relationship between the levels of peroxisome proliferator-activated receptor α (PPARα) mRNA expression and the respiratory function and ultrastructure of mitochondria in the vastus lateralis of patients with COPD. Vastus lateralis biopsies were performed on 14 patients with COPD and 6 control subjects with normal lung function. PPARα mRNA levels in the muscle tissue were detected by real-time PCR. A Clark oxygen electrode was used to assess mitochondrial respiratory function. Mitochondrial number, fractional area in skeletal muscle cross-sections, and Z-line width were observed via transmission electron microscopy. The PPARα mRNA expression was significantly lower in COPD patients with low body mass index (BMIL) than in both COPD patients with normal body mass index (BMIN) and controls. Mitochondrial respiratory function (assessed by respiratory control ratio) was impaired in COPD patients, particularly in BMIL. Compared with that in the control group, mitochondrial number and fractional area were lower in the BMIL group, but were maintained in the BMIN group. Further, the Z-line became narrow in the BMIL group. PPARα mRNA expression was positively related to mitochondrial respiratory function and volume density. In COPD patients with BMIN, mitochondria volume density was maintained, while respiratory function decreased, whereas both volume density and respiratory function decreased in COPD patients with BMIL. PPARα mRNA expression levels are associated with decreased mitochondrial respiratory function and volume density, which may contribute to muscle dysfunction in COPD patients.

Survival in the Rockies of an endangered hybrid swarm from diverged caribou (Rangifer tarandus) lineages.

PubMed

McDevitt, Allan D; Mariani, Stefano; Hebblewhite, Mark; Decesare, Nicholas J; Morgantini, Luigi; Seip, Dale; Weckworth, Byron V; Musiani, Marco

2009-02-01

In North America, caribou (Rangifer tarandus) experienced diversification in separate refugia before the last glacial maximum. Geographical isolation produced the barren-ground caribou (Rangifer tarandus groenlandicus) with its distinctive migratory habits, and the woodland caribou (Rangifer tarandus caribou), which has sedentary behaviour and is now in danger of extinction. Herein we report on the phylogenetics, population structure, and migratory habits of caribou in the Canadian Rockies, utilizing molecular and spatial data for 223 individuals. Mitochondrial DNA analyses show the occurrence of two highly diverged lineages; the Beringian-Eurasian and North American lineages, while microsatellite data reveal that present-day Rockies' caribou populations have resulted from interbreeding between these diverged lineages. An ice-free corridor at the end of the last glaciation likely allowed, for the first time, for barren-ground caribou to migrate from the North and overlap with woodland caribou expanding from the South. The lack of correlation between nuclear and mitochondrial data may indicate that different environmental forces, which might also include human-caused habitat loss and fragmentation, are currently reshaping the population structure of this postglacial hybrid swarm. Furthermore, spatial ecological data show evidence of pronounced migratory behaviour within the study area, and suggest that the probability of being migratory may be higher in individual caribou carrying a Beringian-Eurasian haplotype which is mainly associated with the barren-ground subspecies. Overall, our analyses reveal an intriguing example of postglacial mixing of diverged lineages. In a landscape that is changing due to climatic and human-mediated factors, an understanding of these dynamics, both past and present, is essential for management and conservation of these populations.

MELAS syndrome associated with a new mitochondrial tRNA-Val gene mutation (m.1616A>G).

PubMed

Toyoshima, Yuka; Tanaka, Yuji; Satomi, Kazuo

2017-09-11

We describe the case of a 40-year-old-man with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, with cardiomyopathy and severe heart failure. He had a mitochondrial transfer RNA (tRNA) mutation (m.1616A>G) of the (tRNA-Val) gene, and it was not found in MELAS syndrome ever before. The presence of this newly observed tRNA-Val mutation (m.1616A>G) may induce multiple respiratory chain enzyme deficiencies and contribute to MELAS syndrome symptoms that are associated with mitochondrial DNA (mtDNA) mutations. We report that the pathognomonic symptom in MELAS syndrome caused by this newly observed mtDNA mutation may be rapid progression of cardiomyopathy and severe heart failure. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Expression of a truncated form of the endoplasmic reticulum chaperone protein, σ1 receptor, promotes mitochondrial energy depletion and apoptosis.

PubMed

Shioda, Norifumi; Ishikawa, Kiyoshi; Tagashira, Hideaki; Ishizuka, Toru; Yawo, Hiromu; Fukunaga, Kohji

2012-07-06

The σ1 receptor (σ(1)R) regulates endoplasmic reticulum (ER)/mitochondrial interorganellar Ca(2+) mobilization through the inositol 1,4,5-trisphosphate receptor (IP(3)R). Here, we observed that expression of a novel splice variant of σ(1)R, termed short form σ(1)R (σ(1)SR), has a detrimental effect on mitochondrial energy production and cell survival. σ(1)SR mRNA lacks 47 ribonucleotides encoding exon 2, resulting in a frameshift and formation of a truncated receptor. σ(1)SR localizes primarily in the ER at perinuclear regions and forms a complex with σ(1)R but not with IP(3)R in the mitochondrion-associated ER membrane. Overexpression of both σ(1)R and the truncated isoform promotes mitochondrial elongation with increased ER mitochondrial contact surface. σ(1)R overexpression increases the efficiency of mitochondrial Ca(2+) uptake in response to IP(3)R-driven stimuli, whereas σ(1)SR overexpression reduces it. Most importantly, σ(1)R promotes ATP production via increased mitochondrial Ca(2+) uptake, promoting cell survival in the presence of ER stress. By contrast, σ(1)SR suppresses ATP production following ER stress, enhancing cell death. Taken together, the newly identified σ(1)SR isoform interferes with σ(1)R function relevant to mitochondrial energy production under ER stress conditions, promoting cellular apoptosis.

Effect of Cocoa Polyphenolic Extract on Macrophage Polarization from Proinflammatory M1 to Anti-Inflammatory M2 State

PubMed Central

Dugo, Laura; Belluomo, Maria Giovanna; Fanali, Chiara; Russo, Marina; Cacciola, Francesco

2017-01-01

Polyphenols-rich cocoa has many beneficial effects on human health, such as anti-inflammatory effects. Macrophages function as control switches of the immune system, maintaining the balance between pro- and anti-inflammatory activities. We investigated the hypothesis that cocoa polyphenol extract may affect macrophage proinflammatory phenotype M1 by favoring an alternative M2 anti-inflammatory state on macrophages deriving from THP-1 cells. Chemical composition, total phenolic content, and antioxidant capacity of cocoa polyphenols extracted from roasted cocoa beans were determined. THP-1 cells were activated with both lipopolysaccharides and interferon-γ for M1 or with IL-4 for M2 switch, and specific cytokines were quantified. Cellular metabolism, through mitochondrial oxygen consumption, and ATP levels were evaluated. Here, we will show that cocoa polyphenolic extract attenuated in vitro inflammation decreasing M1 macrophage response as demonstrated by a significantly lowered secretion of proinflammatory cytokines. Moreover, treatment of M1 macrophages with cocoa polyphenols influences macrophage metabolism by promoting oxidative pathways, thus leading to a significant increase in O2 consumption by mitochondrial complexes as well as a higher production of ATP through oxidative phosphorylation. In conclusion, cocoa polyphenolic extract suppresses inflammation mediated by M1 phenotype and influences macrophage metabolism by promoting oxidative pathways and M2 polarization of active macrophages. PMID:28744339

The "fossilized" mitochondrial genome of Liriodendron tulipifera: ancestral gene content and order, ancestral editing sites, and extraordinarily low mutation rate.

PubMed

Richardson, Aaron O; Rice, Danny W; Young, Gregory J; Alverson, Andrew J; Palmer, Jeffrey D

2013-04-15

The mitochondrial genomes of flowering plants vary greatly in size, gene content, gene order, mutation rate and level of RNA editing. However, the narrow phylogenetic breadth of available genomic data has limited our ability to reconstruct these traits in the ancestral flowering plant and, therefore, to infer subsequent patterns of evolution across angiosperms. We sequenced the mitochondrial genome of Liriodendron tulipifera, the first from outside the monocots or eudicots. This 553,721 bp mitochondrial genome has evolved remarkably slowly in virtually all respects, with an extraordinarily low genome-wide silent substitution rate, retention of genes frequently lost in other angiosperm lineages, and conservation of ancestral gene clusters. The mitochondrial protein genes in Liriodendron are the most heavily edited of any angiosperm characterized to date. Most of these sites are also edited in various other lineages, which allowed us to polarize losses of editing sites in other parts of the angiosperm phylogeny. Finally, we added comprehensive gene sequence data for two other magnoliids, Magnolia stellata and the more distantly related Calycanthus floridus, to measure rates of sequence evolution in Liriodendron with greater accuracy. The Magnolia genome has evolved at an even lower rate, revealing a roughly 5,000-fold range of synonymous-site divergence among angiosperms whose mitochondrial gene space has been comprehensively sequenced. Using Liriodendron as a guide, we estimate that the ancestral flowering plant mitochondrial genome contained 41 protein genes, 14 tRNA genes of mitochondrial origin, as many as 7 tRNA genes of chloroplast origin, >700 sites of RNA editing, and some 14 colinear gene clusters. Many of these gene clusters, genes and RNA editing sites have been variously lost in different lineages over the course of the ensuing ∽200 million years of angiosperm evolution.

Evolutionary history of the endangered fish Zoogoneticus quitzeoensis (Bean, 1898) (Cyprinodontiformes: Goodeidae) using a sequential approach to phylogeography based on mitochondrial and nuclear DNA data

PubMed Central

2008-01-01

Background Tectonic, volcanic and climatic events that produce changes in hydrographic systems are the main causes of diversification and speciation of freshwater fishes. Elucidate the evolutionary history of freshwater fishes permits to infer theories on the biotic and geological evolution of a region, which can further be applied to understand processes of population divergence, speciation and for conservation purposes. The freshwater ecosystems in Central Mexico are characterized by their genesis dynamism, destruction, and compartmentalization induced by intense geologic activity and climatic changes since the early Miocene. The endangered goodeid Zoogoneticus quitzeoensis is widely distributed across Central México, thus making it a good model for phylogeographic analyses in this area. Results We addressed the phylogeography, evolutionary history and genetic structure of populations of Z. quitzeoensis through a sequential approach, based on both microsatellite and mitochondrial cytochrome b sequences. Most haplotypes were private to particular locations. All the populations analysed showed a remarkable number of haplotypes. The level of gene diversity within populations was H¯d = 0.987 (0.714 – 1.00). However, in general the nucleotide diversity was low, π = 0.0173 (0.0015 – 0.0049). Significant genetic structure was found among populations at the mitochondrial and nuclear level (ΦST = 0.836 and FST = 0.262, respectively). We distinguished two well-defined mitochondrial lineages that were separated ca. 3.3 million years ago (Mya). The time since expansion was ca. 1.5 × 106 years ago for Lineage I and ca. 860,000 years ago for Lineage II. Also, genetic patterns of differentiation, between and within lineages, are described at different historical timescales. Conclusion Our mtDNA data indicates that the evolution of the different genetic groups is more related to ancient geological and climatic events (Middle Pliocene, ca. 3.3 Mya) than to the current

Retrospective assessment of the most common mitochondrial DNA mutations in a large Hungarian cohort of suspect mitochondrial cases.

PubMed

Remenyi, Viktoria; Inczedy-Farkas, Gabriella; Komlosi, Katalin; Horvath, Rita; Maasz, Anita; Janicsek, Ingrid; Pentelenyi, Klara; Gal, Aniko; Karcagi, Veronika; Melegh, Bela; Molnar, Maria Judit

2015-08-01

Prevalence estimations for mitochondrial disorders still vary widely and only few epidemiologic studies have been carried out so far. With the present work we aim to give a comprehensive overview about frequencies of the most common mitochondrial mutations in Hungarian patients. A total of 1328 patients were tested between 1999 and 2012. Among them, 882 were screened for the m.3243A > G, m.8344A > G, m.8993T > C/G mutations and deletions, 446 for LHON primary mutations. The mutation frequency in our cohort was 2.61% for the m.3243A > G, 1.47% for the m.8344A > G, 17.94% for Leber's Hereditary Optic Neuropathy (m.3460G > A, m.11778G > A, m.14484T > C) and 0.45% for the m.8993T > C/G substitutions. Single mtDNA deletions were detected in 14.97%, while multiple deletions in 6.01% of the cases. The mutation frequency in Hungarian patients suggestive of mitochondrial disease was similar to other Caucasian populations. Further retrospective studies of different populations are needed in order to accurately assess the importance of mitochondrial diseases and manage these patients.

Role of the putative structural protein Sed1p in mitochondrial genome maintenance.

PubMed

Phadnis, Naina; Ayres Sia, Elaine

2004-09-24

The nuclear gene MIP1 encodes the mitochondrial DNA polymerase responsible for replicating the mitochondrial genome in Saccharomyces cerevisiae. A number of other factors involved in replicating and segregating the mitochondrial genome are yet to be identified. Here, we report that a bacterial two-hybrid screen using the mitochondrial polymerase, Mip1p, as bait identified the yeast protein Sed1p. Sed1p is a cell surface protein highly expressed in the stationary phase. We find that several modified forms of Sed1p are expressed and the largest of these forms interacts with the mitochondrial polymerase in vitro. Deletion of SED1 causes a 3.5-fold increase in the rate of mitochondrial DNA point mutations as well as a 4.3-fold increase in the rate of loss of respiration. In contrast, we see no change in the rate of nuclear point mutations indicating the specific role of Sed1p function in mitochondrial genome stability. Indirect immunofluorescence analysis of Sed1p localization shows that Sed1p is targeted to the mitochondria. Moreover, Sed1p is detected in purified mitochondrial fractions and the localization to the mitochondria of the largest modified form is insensitive to the action of proteinase K. Deletion of the sed1 gene results in a reduction in the quantity of Mip1p and also affects the levels of a mitochondrially-expressed protein, Cox3p. Our results point towards a role for Sed1p in mitochondrial genome maintenance.

Mitochondrial ryanodine-sensitive Ca2+ channels of rat liver.

PubMed

Kupynyak, N I; Ikkert, O V; Shlykov, S G; Babich, L G; Manko, V V

2017-01-01

To examine ryanodine-sensitive Ca 2+ channels in mitochondria of rat hepatocytes and their role in energy state of the cells via investigation of the ryanodine effect on mitochondrial membrane potential. Oxygen consumption was measured by polarography using the Clark electrode. The substrates of oxidation such as pyruvate (5mM), α-ketoglutarate (5mM), or succinate (5mM) were used. Oxidative phosphorylation was stimulated by the addition of adenosine diphosphate (200nM). Mitochondrial membrane potential was measured using a voltage-sensitive fluorescent probe tetramethylrhodamine-methyl-ester (0.1μM) and was analyzed by a flow cytometer. To evaluate the intact mitochondria, we used carbonil cyanide m-chlorophenyl hydrazone (CCCP, 10μM). Changes in the ionized calcium concentration in rat liver mitochondria were measured using a fluorescent probe Fluo-4 AM. Effect of ryanodine on oxygen consumption of rat liver mitochondria depends on the oxidation substrate and the incubation time. Oxidation of pyruvate in the presence of ryanodine (0.05μM) decreased the membrane potential of rat liver mitochondria by 38.4%. At higher concentrations, ryanodine (0.1μM or 1μM) led to decrease of membrane potential by 51.7% and 42.8%, respectively. In contrast, oxidation of α-ketoglutarate in the presence of ryanodine (0.05μM) increased mitochondrial membrane potential by 16.8%. However, at higher concentrations, ryanodine (0.1μM or 1μM) triggered a decreasing of membrane potential by 42.5% and 31.0%, respectively. Therefore, ryanodine at various concentrations (0.05μM, 0.1μM, or 1μM) causes differential effects on Ca 2+ concentration in the mitochondria matrix under oxidation of pyruvate or α-ketoglutarate. The data suggest the presence of ryanodine receptors in mitochondrial membrane of rat hepatocytes. Their inhibition with higher concentrations of ryanodine leads to decreasing of intra-mitochondrial Ca 2+ concentration and affecting the energy state of mictochondria

Dnmt1 regulates the myogenic lineage specification of muscle stem cells.

PubMed

Liu, Renjing; Kim, Kun-Yong; Jung, Yong-Wook; Park, In-Hyun

2016-10-18

DNA methylation is an important epigenetic mark that regulates gene expression. Dnmt1 plays an important role in maintaining DNA methylation patterns on daughter DNA strands. Studies have shed light into the functional role of Dnmt1 regulation in the hematopoietic and epidermal systems. Here we show that Dnmt1 is required for myogenesis. Loss of Dnmt1 results in reduced expression of myogenic genes and defects in myogenic differentiation. We have utilized a conditional knockout mouse approach to examine the functional consequences of Dnmt1 depletion specifically in the developing muscle. These mice were born runted, with smaller body weights, and reduced ability to form myotubes in vitro. We show that expression of Id-1, a negative regulator of myogenesis, is enhanced in Dnmt1-deficient cultures, leading to enhanced transdifferentiation of myoblasts toward the osteogenic lineage. Thus, these studies demonstrate that Dnmt1 influences cellular identity and determines lineage fidelity.

Dnmt1 regulates the myogenic lineage specification of muscle stem cells

PubMed Central

Liu, Renjing; Kim, Kun-Yong; Jung, Yong-Wook; Park, In-Hyun

2016-01-01

DNA methylation is an important epigenetic mark that regulates gene expression. Dnmt1 plays an important role in maintaining DNA methylation patterns on daughter DNA strands. Studies have shed light into the functional role of Dnmt1 regulation in the hematopoietic and epidermal systems. Here we show that Dnmt1 is required for myogenesis. Loss of Dnmt1 results in reduced expression of myogenic genes and defects in myogenic differentiation. We have utilized a conditional knockout mouse approach to examine the functional consequences of Dnmt1 depletion specifically in the developing muscle. These mice were born runted, with smaller body weights, and reduced ability to form myotubes in vitro. We show that expression of Id-1, a negative regulator of myogenesis, is enhanced in Dnmt1-deficient cultures, leading to enhanced transdifferentiation of myoblasts toward the osteogenic lineage. Thus, these studies demonstrate that Dnmt1 influences cellular identity and determines lineage fidelity. PMID:27752090

Ethiopian mitochondrial DNA heritage: tracking gene flow across and around the gate of tears.

PubMed

Kivisild, Toomas; Reidla, Maere; Metspalu, Ene; Rosa, Alexandra; Brehm, Antonio; Pennarun, Erwan; Parik, Juri; Geberhiwot, Tarekegn; Usanga, Esien; Villems, Richard

2004-11-01

Approximately 10 miles separate the Horn of Africa from the Arabian Peninsula at Bab-el-Mandeb (the Gate of Tears). Both historic and archaeological evidence indicate tight cultural connections, over millennia, between these two regions. High-resolution phylogenetic analysis of 270 Ethiopian and 115 Yemeni mitochondrial DNAs was performed in a worldwide context, to explore gene flow across the Red and Arabian Seas. Nine distinct subclades, including three newly defined ones, were found to characterize entirely the variation of Ethiopian and Yemeni L3 lineages. Both Ethiopians and Yemenis contain an almost-equal proportion of Eurasian-specific M and N and African-specific lineages and therefore cluster together in a multidimensional scaling plot between Near Eastern and sub-Saharan African populations. Phylogeographic identification of potential founder haplotypes revealed that approximately one-half of haplogroup L0-L5 lineages in Yemenis have close or matching counterparts in southeastern Africans, compared with a minor share in Ethiopians. Newly defined clade L6, the most frequent haplogroup in Yemenis, showed no close matches among 3,000 African samples. These results highlight the complexity of Ethiopian and Yemeni genetic heritage and are consistent with the introduction of maternal lineages into the South Arabian gene pool from different source populations of East Africa. A high proportion of Ethiopian lineages, significantly more abundant in the northeast of that country, trace their western Eurasian origin in haplogroup N through assorted gene flow at different times and involving different source populations.

Phylogenetic relationships and biogeographical patterns in Circum-Mediterranean subfamily Leuciscinae (Teleostei, Cyprinidae) inferred from both mitochondrial and nuclear data

PubMed Central

2010-01-01

Background Leuciscinae is a subfamily belonging to the Cyprinidae fish family that is widely distributed in Circum-Mediterranean region. Many efforts have been carried out to deciphering the evolutionary history of this group. Thus, different biogeographical scenarios have tried to explain the colonization of Europe and Mediterranean area by cyprinids, such as the "north dispersal" or the "Lago Mare dispersal" models. Most recently, Pleistocene glaciations influenced the distribution of leuciscins, especially in North and Central Europe. Weighing up these biogeographical scenarios, this paper constitutes not only the first attempt at deciphering the mitochondrial and nuclear relationships of Mediterranean leuciscins but also a test of biogeographical hypotheses that could have determined the current distribution of Circum-Mediterranean leuciscins. Results A total of 4439 characters (mitochondrial + nuclear) from 321 individuals of 176 leuciscine species rendered a well-supported phylogeny, showing fourteen main lineages. Analyses of independent mitochondrial and nuclear markers supported the same main lineages, but basal relationships were not concordant. Moreover, some incongruence was found among independent mitochondrial and nuclear phylogenies. The monophyly of some poorly known genera such as Pseudophoxinus and Petroleuciscus was rejected. Representatives of both genera belong to different evolutionary lineages. Timing of cladogenetic events among the main leuciscine lineages was gained using mitochondrial and all genes data set. Conclusions Adaptations to a predatory lifestyle or miniaturization have superimposed the morphology of some species. These species have been separated into different genera, which are not supported by a phylogenetic framework. Such is the case of the genera Pseudophoxinus and Petroleuciscus, which real taxonomy is not well known. The diversification of leuciscine lineages has been determined by intense vicariant events following the

MacroH2A1.1 regulates mitochondrial respiration by limiting nuclear NAD+ consumption.

PubMed

Posavec Marjanović, Melanija; Hurtado-Bagès, Sarah; Lassi, Maximilian; Valero, Vanesa; Malinverni, Roberto; Delage, Hélène; Navarro, Miriam; Corujo, David; Guberovic, Iva; Douet, Julien; Gama-Perez, Pau; Garcia-Roves, Pablo M; Ahel, Ivan; Ladurner, Andreas G; Yanes, Oscar; Bouvet, Philippe; Suelves, Mònica; Teperino, Raffaele; Pospisilik, J Andrew; Buschbeck, Marcus

2017-11-01

Histone variants are structural components of eukaryotic chromatin that can replace replication-coupled histones in the nucleosome. The histone variant macroH2A1.1 contains a macrodomain capable of binding NAD + -derived metabolites. Here we report that macroH2A1.1 is rapidly induced during myogenic differentiation through a switch in alternative splicing, and that myotubes that lack macroH2A1.1 have a defect in mitochondrial respiratory capacity. We found that the metabolite-binding macrodomain was essential for sustained optimal mitochondrial function but dispensable for gene regulation. Through direct binding, macroH2A1.1 inhibits basal poly-ADP ribose polymerase 1 (PARP-1) activity and thus reduces nuclear NAD + consumption. The resultant accumulation of the NAD + precursor NMN allows for maintenance of mitochondrial NAD + pools that are critical for respiration. Our data indicate that macroH2A1.1-containing chromatin regulates mitochondrial respiration by limiting nuclear NAD + consumption and establishing a buffer of NAD + precursors in differentiated cells.

A hybrid zone between Bathymodiolus mussel lineages from eastern Pacific hydrothermal vents.

PubMed

Johnson, Shannon B; Won, Yong-Jin; Harvey, Julio Bj; Vrijenhoek, Robert C

2013-01-24

The inhabitants of deep-sea hydrothermal vents occupy ephemeral island-like habitats distributed sporadically along tectonic spreading-centers, back-arc basins, and volcanically active seamounts. The majority of vent taxa undergo a pelagic larval phase, and thus varying degrees of geographical subdivision, ranging from no impedance of dispersal to complete isolation, often exist among taxa that span common geomorphological boundaries. Two lineages of Bathymodiolus mussels segregate on either side of the Easter Microplate, a boundary that separates the East Pacific Rise from spreading centers connected to the Pacific-Antarctic Ridge. A recent sample from the northwest flank of the Easter Microplate contained an admixture of northern and southern mitochondrial haplotypes and corresponding alleles at five nuclear gene loci. Genotypic frequencies in this sample did not fit random mating expectation. Significant heterozygote deficiencies at nuclear loci and gametic disequilibria between loci suggested that this transitional region might be a 'Tension Zone' maintained by immigration of parental types and possibly hybrid unfitness. An analysis of recombination history in the nuclear genes suggests a prolonged history of parapatric contact between the two mussel lineages. We hereby elevate the southern lineage to species status as Bathymodiolus antarcticus n. sp. and restrict the use of Bathymodiolus thermophilus to the northern lineage. Because B. thermophilus s.s. exhibits no evidence for subdivision or isolation-by-distance across its 4000 km range along the EPR axis and Galápagos Rift, partial isolation of B. antarcticus n. sp. requires explanation. The time needed to produce the observed degree of mitochondrial differentiation is consistent with the age of the Easter Microplate (2.5 to 5.3 million years). The complex geomorphology of the Easter Microplate region forces strong cross-axis currents that might disrupt self-recruitment of mussels by removing

In vitro development of Haemoproteus parasites: the efficiency of reproductive cells increase during simultaneous sexual process of different lineages.

PubMed

Valkiūnas, Gediminas; Palinauskas, Vaidas; Ilgūnas, Mikas; Bernotienė, Rasa; Iezhova, Tatjana A

2014-04-01

Recent in vitro experimental studies reported the complex patterns of haemosporidian (Haemosporida) between-lineage interactions, which prevent mixing of lineages during simultaneous sexual process. Numerous anomalous ookinetes have been observed; these are not involved in sporogony. Massive development of such ookinetes might influence parasite transmission but is insufficiently investigated. The simultaneous sexual process of several lineages is a common phenomenon in vectors due to high prevalence of haemosporidian co-infections in wildlife. It remains unclear if the number of anomalous ookinetes changes during dual-infection sporogony in comparison with the single-infection process. We calculated proportions of the anomalous and normal ookinetes, which developed during single-infection (control) and dual-infection experiments in vitro conditions. Three mitochondrial cytochrome b lineages belonging to three Haemoproteus spp. (Haemosporida, Haemoproteidae) were isolated from naturally infected passerine birds. Sexual process and ookinete development were initiated in vitro by mixing blood containing mature gametocytes of two different parasites; the following experiments were performed: (1) Haemoproteus tartakovskyi (lineage hSISKIN1) × Haemoproteus lanii (lineage hRBS4) and (2) Haemoproteus belopolskyi (hHIICT3) × H. lanii (hRBS4). Genetic difference between lineages was 5.0-5.9%. Normal and anomalous ookinetes developed in all control and dual-infection experiments. The number of anomalous ookinetes markedly decreased, and normal ookinetes increased in all dual-infection experiments in comparison with those in controls, except for H. belopolskyi, in which proportion of the anomalous and normal ookinetes did not change. This study shows that simultaneous sexual process of two genetically distant lineages of haemosporidian parasites might increase the efficiency of reproductive cells, resulting in the development of a greater number of normal ookinetes. The

Recombination and positive selection contributed to the evolution of Listeria monocytogenes lineages III and IV, two distinct and well supported uncommon L. monocytogenes lineages.