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1.
Enzymes ; 45: 257-287, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31627879

RESUMO

The mitochondrial genome encodes proteins essential for the oxidative phosphorylation and, consequently, for proper mitochondrial function. Its localization and, possibly, structural organization contribute to higher DNA damage accumulation, when compared to the nuclear genome. In addition, the mitochondrial genome mutates at rates several times higher than the nuclear, although the causal relationship between these events are not clearly established. Maintaining mitochondrial DNA stability is critical for cellular function and organismal fitness, and several pathways contribute to that, including damage tolerance and bypass, degradation of damaged genomes and DNA repair. Despite initial evidence suggesting that mitochondria lack DNA repair activities, most DNA repair pathways have been at least partially characterized in mitochondria from several model organisms, including humans. In this chapter, we review what is currently known about how the main DNA repair pathways operate in mitochondria and contribute to mitochondrial DNA stability, with focus on the enzymology of mitochondrial DNA repair.


Assuntos
Dano ao DNA , Reparo do DNA , DNA Mitocondrial/metabolismo , Mitocôndrias/genética , Humanos
2.
Hum Genet ; 138(10): 1183-1200, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31471722

RESUMO

The glutamate pyruvate transaminase 2 (GPT2) gene produces a nuclear-encoded mitochondrial enzyme that catalyzes the reversible transfer of an amino group from glutamate to pyruvate, generating alanine and alpha-ketoglutarate. Recessive mutations in GPT2 have been recently identified in a new syndrome involving intellectual and developmental disability (IDD), postnatal microcephaly, and spastic paraplegia. We have identified additional families with recessive GPT2 mutations and expanded the phenotype to include small stature. GPT2 loss-of-function mutations were identified in four families, nine patients total, including: a homozygous mutation in one child [c.775T>C (p.C259R)]; compound heterozygous mutations in two siblings [c.812A>C (p.N271T)/c.1432_1433delGT (p.V478Rfs*73)]; a novel homozygous, putative splicing mutation [c.1035C>T (p.G345=)]; and finally, a recurrent mutation, previously identified in a distinct family [c.1210C>T (p.R404*)]. All patients were diagnosed with IDD. A majority of patients had remarkably small stature throughout development, many < 1st percentile for height and weight. Given the potential biological function of GPT2 in cellular growth, this phenotype is strongly suggestive of a newly identified clinical susceptibility. Further, homozygous GPT2 mutations manifested in at least 2 of 176 families with IDD (approximately 1.1%) in a Pakistani cohort, thereby representing a relatively common cause of recessive IDD in this population, with recurrence of the p.R404* mutation in this population. Based on variants in the ExAC database, we estimated that approximately 1 in 248 individuals are carriers of moderately or severely deleterious variants in GPT2.


Assuntos
Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/genética , Genes Recessivos , Predisposição Genética para Doença , Mutação , Fenótipo , Transaminases/genética , Adolescente , Alelos , Substituição de Aminoácidos , Deficiências do Desenvolvimento/metabolismo , Ativação Enzimática , Éxons , Feminino , Frequência do Gene , Estudos de Associação Genética , Genética Populacional , Genótipo , Humanos , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Imagem por Ressonância Magnética , Masculino , Mitocôndrias/genética , Mitocôndrias/metabolismo , Modelos Moleculares , Linhagem , Conformação Proteica , Sítios de Splice de RNA , Análise de Sequência de DNA , Relação Estrutura-Atividade , Transaminases/química , Transaminases/metabolismo
3.
Anticancer Res ; 39(9): 4865-4876, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31519589

RESUMO

BACKGROUND/AIM: Hypoxia promotes tumor proliferation and metastasis in colorectal cancer (CRC). Since the tumor microenvironment is generally characterized by hypoxia, its understanding is important for cancer therapy. We hypothesized that hypoxia promotes the mitochondrial function, mobility, and proliferation of CRC by up-regulating peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). MATERIALS AND METHODS: To assess the effects of PGC-1α under hypoxia, we investigated the mitochondrial function, cell motility, and sphere formation as well as proliferation and apoptosis of CRC. RESULTS: Under hypoxia, we confirmed the increased expression of PGC-1α and reduced production of reactive oxygen species (ROS) by activating anti-oxidant enzymes. Also, up-regulation of PGC-1α enhanced the motility, sphere formation, and proliferation of CRC. Under the presence of the anti-cancer drug 5-fluorouracil (5FU), up-regulation of PGC-1α under hypoxia promoted resistance of CRC against 5FU-induced apoptosis. CONCLUSION: Targeting PGC-1α could to be a powerful strategy for CRC therapy.


Assuntos
Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Hipóxia/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Apoptose , Catalase/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Neoplasias Colorretais/patologia , Resistencia a Medicamentos Antineoplásicos , Complexo I de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Modelos Biológicos , Fosforilação Oxidativa , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo
4.
BMC Evol Biol ; 19(1): 177, 2019 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-31484504

RESUMO

BACKGROUND: Triplophysa stoliczkae is the most widespread species in the genus Triplophysa and may have originated from morphological convergence. To understand the evolutionary history of T. stoliczkae, we employed a multilocus approach to investigate the phylogenetics and the morphological evolution of T. stoliczkae on the Qinghai-Tibetan Plateau. RESULTS: All phylogenetic analyses (two mitochondrial and five nuclear loci), a genealogical sorting index and species tree inferences suggested that T. stoliczkae consists of distinct lineages that were not closest relatives. The time estimation indicated that the divergence events between "T. stoliczkae" and other Triplophysa species occurred from approximately 0.10 to 4.51 Ma. The ancestral state analyses supported the independent evolution of T. stoliczkae morphology in distinct lineages. The morphometric analysis and convergence estimates demonstrated significant phenotypic convergence among "T. stoliczkae" lineages. CONCLUSIONS: Triplophysa stoliczkae includes 4 different lineages with similar morphologies. The increasingly harsh environments that have occurred since the Pliocene have driven the occurrences of scrape-feeding fish in the genus Triplophysa. Morphological adaptations associated with scrape-feeding behavior resulted in convergences and the artificial lumping of four different species in the nominal taxon T. stoliczkae. A taxonomic revision for T. stoliczkae is needed.


Assuntos
Cipriniformes/classificação , Cipriniformes/genética , Animais , Evolução Biológica , China , Especiação Genética , Mitocôndrias/genética , Filogenia , Análise de Sequência de DNA , Tibet
5.
Adv Exp Med Biol ; 1158: 101-117, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31452138

RESUMO

Targeted mass spectrometry in the selected or parallel reaction monitoring (SRM or PRM) mode is a widely used methodology to quantify proteins based on so-called signature or proteotypic peptides. SRM has the advantage of being able to quantify a range of proteins in a single analysis, for example, to measure the level of enzymes comprising a biochemical pathway. In this chapter, we will detail how to set up an SRM assay on the example of the mitochondrial protein succinate dehydrogenase [ubiquinone] flavoprotein subunit (mouse UniProt-code Q8K2B3). First, we will outline the in silico assay design including the choice of peptides based on a range of properties. We will further delineate different quantification strategies and introduce the reader to LC-MS assay development including the selection of the optimal peptide charge state and fragment ions as well as a discussion of the dynamic range of detection. The chapter will close with an application from the area of mitochondrial biology related to the quantification of a set of proteins isolated from mouse liver mitochondria in a study on mitochondrial respiratory flux decline in aging mouse muscle.


Assuntos
Mitocôndrias , Proteômica , Animais , Cromatografia Líquida , Camundongos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Peptídeos/química , Proteômica/instrumentação , Proteômica/métodos , Espectrometria de Massas em Tandem
6.
Adv Exp Med Biol ; 1158: 217-246, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31452143

RESUMO

Mitochondria maintain and express their own genome, referred to as mtDNA, which is required for proper mitochondrial function. While mutations in mtDNA can cause a heterogeneous array of disease phenotypes, there is currently no cure for this collection of diseases. Here, we will cover characteristics of the mitochondrial genome important for understanding the pathology associated with mtDNA mutations, and review recent approaches that are being developed to treat and prevent mtDNA disease. First, we will discuss mitochondrial replacement therapy (MRT), where mitochondria from a healthy donor replace maternal mitochondria harbouring mutant mtDNA. In addition to ethical concerns surrounding this procedure, MRT is only applicable in cases where the mother is known or suspected to carry mtDNA mutations. Thus, there remains a need for other strategies to treat patients with mtDNA disease. To this end, we will also discuss several alternative means to reduce the amount of mutant mtDNA present in cells. Such methods, referred to as heteroplasmy shifting, have proven successful in animal models. In particular, we will focus on the approach of targeting engineered endonucleases to specifically cleave mutant mtDNA. Together, these approaches offer hope to prevent the transmission of mtDNA disease and potentially reduce the impact of mtDNA mutations.


Assuntos
Terapia Genética , Doenças Mitocondriais , Animais , DNA Mitocondrial , Modelos Animais de Doenças , Terapia Genética/tendências , Genoma Mitocondrial , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Doenças Mitocondriais/terapia , Mutação
7.
Adv Exp Med Biol ; 1158: 247-255, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31452144

RESUMO

The maternally inherited mitochondrial DNA (mtDNA) is located inside every mitochondrion, in variable number of copies, and it contains 37 crucial genes for cellular bioenergetics. This chapter will discuss the unique features of this circular genome including heteroplasmy, haplogroups, among others, along with the corresponding clinical relevance for each. The discussion also covers the nuclear-encoded mitochondrial genes (N > 1000) and the epistatic interactions between mtDNA and the nuclear genome. Examples of mitochondrial diseases related to specific mtDNA mutation sites of relevance for humans are provided. This chapter aims to provide an overview of mitochondrial genetics as an emerging hot topic for the future of medicine.


Assuntos
Metabolismo Energético , Mitocôndrias , DNA Mitocondrial/genética , Metabolismo Energético/genética , Epistasia Genética , Genes Mitocondriais/genética , Genoma/genética , Humanos , Mitocôndrias/genética , Doenças Mitocondriais/genética , Mutação
8.
Adv Exp Med Biol ; 1158: 257-267, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31452145

RESUMO

Mitochondrial disease can arise due to pathogenic sequence variants in the mitochondrial DNA (mtDNA) that prevent cells from meeting their energy demands. Mitochondrial diseases are often fatal and currently there are no treatments directed towards the underlying cause of disease. Pathogenic variants in mtDNA often exist in a state of heteroplasmy, with coexistence of pathogenic and wild type mtDNA. The load of heteroplasmy, defined as the relative amount of pathogenic mtDNA to wild type mtDNA, corresponds to timing and symptom severity. Thus, changing the heteroplasmy load may lead to a shift in disease onset and symptom severity. Here we review techniques aimed at preventing inheritance of pathogenic mtDNA via mitochondrial replacement therapy (MRT) and strategies geared toward shifting of heteroplasmy in individuals with active mitochondrial disease. MRT strategies seek to create embryos with the nuclear genetic makeup of the intended parents and wild type mtDNA from a donor in order to avoid known maternal pathogenic variants. Heteroplasmy shift approaches in patients are of two categories: nuclease dependent and nuclease independent strategies. Despite initial success in mouse models and patient cells, these techniques have not reached clinical use. Translational attempts in this area are urgently needed to improve therapies for a currently untreatable set of disorders.


Assuntos
Terapia Genética , Doenças Mitocondriais , Animais , Núcleo Celular , DNA Mitocondrial/genética , Terapia Genética/tendências , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Doenças Mitocondriais/terapia
9.
Adv Exp Med Biol ; 1158: 269-277, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31452146

RESUMO

Mitochondria play a central role in maintaining normal cellular homeostasis as well as contributing to the pathogenesis of numerous disease states. The advent of CRISPR-Cas9 screening technologies has greatly accelerated the study of mitochondrial biology. In this chapter, we review the various CRISPR-Cas9 screening platforms that are currently available and prior studies that leveraged this technology to identify genes involved in mitochondrial biology in both healthy and disease states. In addition, we discuss the challenges associated with current CRISPR-Cas9 platforms and potential solutions to further enhance this promising technology.


Assuntos
Sistemas CRISPR-Cas , Mitocôndrias , Doenças Mitocondriais , Fenômenos Fisiológicos Celulares/genética , Mitocôndrias/genética , Mitocôndrias/patologia , Doenças Mitocondriais/genética , Pesquisa/tendências
10.
J Agric Food Chem ; 67(36): 10097-10106, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31418272

RESUMO

Ginkgolic acids (GAs) are found in the leaves, nuts, and testa of Ginkgo biloba and have been reported to exhibit antitumor, antibacterial, and pro-apoptotic activities. However, their role in mitochondrial function is still unclear. Our previous study showed that genes related to the mitochondria present significant changes in GA-treated mouse bone marrow stromal cells. We hypothesize that GAs may regulate mitochondrial function. Here, we found that GA treatment induced mitochondrial fragmentation, reduced mtDNA copy numbers and mitochondrial protein levels, and impaired mitochondrial adenosine 5'-triphosphate production and oxygen consumption. The GA-induced mitochondrial mass loss may be due to decreased mitochondrial biogenesis. In addition, abolishing autophagy by Atg7 knockout or the administration of an autophagy inhibitor can restore the GA-induced decrease in mitochondrial mass. Furthermore, FUNDC1 knockdown restored the GA-induced changes in mitochondrial mass reduction and mitochondrial membrane potential loss. Together, our studies demonstrated that GAs impaired mitochondrial function by decreasing mitochondrial biogenesis and promoting FUNDC1-dependent mitophagy.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Proteínas de Membrana/metabolismo , Mitocôndrias/efeitos dos fármacos , Degradação Mitocondrial/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Salicilatos/farmacologia , Autofagia/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , Ginkgo biloba/química , Células HeLa , Humanos , Proteínas de Membrana/genética , Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Biogênese de Organelas
11.
Cancer Sci ; 110(9): 2856-2866, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31314163

RESUMO

4-Hydroxynonenal (HNE) is an important product of plasma membrane lipid peroxidation, which is a cause of cell and tissue injury. Mitochondrial DNA (mtDNA)-depleted ρ0 cells were established using human cervical cancer and oral squamous cell carcinoma cell lines. We investigated the effect of reactive oxygen species in ρ0 cells, especially the mechanism of hydrogen peroxide (H2 O2 )-mediated cell death. These cell were subjected to high oxidative stress and, compared with their parental cells, showed greater sensitivity to H2 O2 and high lipid peroxidation. Upregulation of HNE in the plasma membrane was observed prior to the increase in intracellular H2 O2 . The amount of oxidized lipid present changed H2 O2 permeability and administration of oxidized lipid led to further cell death after treatment with H2 O2 . Expression levels of lipoxygenase ALOX genes (ie ALOX5, ALOX12, and ALOX15) were upregulated in ρ0 cells, as were expression levels of ALOX12 and ALOX15 proteins. ALOX5 protein was mainly distributed in the nucleus, while ALOX12 and ALOX15 proteins were distributed in the nucleus and the cytoplasm. Although expression of COX2 gene was upregulated, its protein expression did not increase. ALOX (especially ALOX15) may be involved in the sensitivity of cancer cells to treatment. These data offer promise for the development of novel anticancer agents by altering the oxidation state of the plasma membrane. Our results showed that lipid peroxidation status is important for H2 O2 sensitivity and that ALOX15 is involved in lipid peroxidation status.


Assuntos
Apoptose/efeitos dos fármacos , Permeabilidade da Membrana Celular/genética , DNA Mitocondrial/genética , Peróxido de Hidrogênio/administração & dosagem , Peroxidação de Lipídeos/genética , Neoplasias/patologia , Aldeídos/metabolismo , Araquidonato 15-Lipoxigenase/metabolismo , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Resistencia a Medicamentos Antineoplásicos , Complexo de Proteínas da Cadeia de Transporte de Elétrons/genética , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacocinética , Mitocôndrias/genética , Mitocôndrias/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/genética , Estresse Oxidativo/efeitos dos fármacos , Éteres Fosfolipídicos/administração & dosagem , Regulação para Cima
12.
BMC Evol Biol ; 19(1): 145, 2019 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-31311504

RESUMO

BACKGROUND: China is an important biogeographical zone in which the genetic legacies of the Tertiary and Quaternary periods are abundant, and the contemporary geography environment plays an important role in species distribution. Therefore, many biogeographical studies have focused on the organisms of the region, especially zooplankton, which is essential in the formation of biogeographical principles. Moreover, the generality of endemism also reinforces the need for detailed regional studies of zooplankton. Bosmina, a group of cosmopolitan zooplankton, is difficult to identify by morphology, and no genetic data are available to date to assess this species complex in China. In this study, 48 waterbodies were sampled covering a large geographical and ecological range in China, the goal of this research is to explore the species distribution of Bosmina across China and to reveal the genetic information of this species complex, based on two genetic markers (a mtDNA 16S and a nuclear ITS). The diversity of taxa in the Bosmina across China was investigated using molecular tools for the first time. RESULTS: Two main species were detected in 35 waterbodies: an endemic east Asia B. fatalis, and the B. longirostris that has a Holarctic distribution. B. fatalis had lower genetic polymorphism and population differentiation than B. longirostris. B. fatalis was preponderant in central and eastern China, whereas B. longirostris was dominated in western China. The third lineage (B. hagmanni) was only detected in a reservoir (CJR) of eastern China (Guangdong province). Bosmina had limited distribution on the Tibetan plateau. CONCLUSIONS: This study revealed that the biogeography of Bosmina appear to be affected by historical events (Pleistocene glaciations) and contemporary environment (such as altitude, eutrophication and isolated habitat).


Assuntos
Cladóceros/genética , DNA Intergênico/genética , DNA Mitocondrial/genética , Variação Genética , Animais , Núcleo Celular/genética , China , Ecossistema , Marcadores Genéticos , Geografia , Haplótipos/genética , Funções Verossimilhança , Mitocôndrias/genética , Filogenia , Polimorfismo Genético , Zooplâncton/genética
13.
J Agric Food Chem ; 67(31): 8510-8519, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31294559

RESUMO

Acrylamide, mainly formed in Maillard browning reaction during food processing, causes defects in liver circadian clock and mitochondrial function by inducing oxidative stress. Resveratrol is a polyphenol that has powerful antioxidant and anti-inflammatory activity. However, the preventive effects of resveratrol on acrylamide-triggered oxidative damage and circadian rhythm disorders are unclear at the current stage. The present research revealed that resveratrol pretreatment prevented acrylamide-induced cell death, mitochondrial dysfunction, and inflammatory responses in HepG2 liver cells. Acrylamide significantly triggered disorders of circadian genes transcription and protein expressions including Bmal1 and Cry 1 in primary hepatocytes, which were prevented by resveratrol pretreatment. Moreover, we found that the beneficial effects of resveratrol on stimulating Nrf2/NQO-1 pathway and mitochondrial respiration complex expressions in acrylamide-treated cells were Bmal1-dependent. Similarly, the inhibitory effects of resveratrol on inflammation signaling NF-κB were Cry1-dependent. In conclusion, these results demonstrated resveratrol could be a promising compound in suppressing acrylamide-induced hepatotoxicity and balancing the circadian clock.


Assuntos
Fatores de Transcrição ARNTL/imunologia , Acrilamida/toxicidade , Transtornos Cronobiológicos/imunologia , Criptocromos/imunologia , Hepatócitos/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Resveratrol/farmacologia , Fatores de Transcrição ARNTL/genética , Animais , Transtornos Cronobiológicos/tratamento farmacológico , Transtornos Cronobiológicos/genética , Transtornos Cronobiológicos/fisiopatologia , Ritmo Circadiano/efeitos dos fármacos , Criptocromos/genética , Células Hep G2 , Hepatócitos/imunologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/genética , Mitocôndrias/imunologia
14.
Gene ; 713: 143967, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31279710

RESUMO

Phylogenetic tree using mitochondrial genes and nuclear genes have long been used for augmenting biological classification and understanding evolutionary processes in different lineage of life. But a basic question still exists for finding the most suitable gene for constructing robust phylogenetic tree. Much of the controversy appears due to monophyletic, paraphyletic and polyphyletic clade making deviations from original taxonomy. In the present study we report the first complete mitochondrial genome (mitogenome) of queen loach, generated through next-generation sequencing methods. The assembled mitogenome is a 16,492 bp circular DNA, comprising of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. Further in this study we also investigated the suitability of different mitochondrial region for phylogenetic analysis in Cyprinidae and loach group. For this genetic tree were constructed on COI, COII, COIII, 16S rRNA, 12S rRNA, Cyt b, ATPase 6, D-loop, ND1, ND2, ND3, ND4, ND5, and ND6 along with complete mitogenome. The complete mitogenome based phylogenetic tree got inclusive support from available classical taxonomy for these groups. On individual gene basis Cyt b, 12S rRNA, ND2 and ND3 also produced perfect clade at family and subfamily level. For rest of the genes polyphyly were observed for the fishes belonging to same family or subfamily which makes their use questionable for phylogenetic tree construction.


Assuntos
Cipriniformes/genética , Genes Mitocondriais , Genoma Mitocondrial , Mitocôndrias/genética , Filogenia , Animais , Análise de Sequência de DNA
15.
Nat Commun ; 10(1): 2901, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31263101

RESUMO

Dysregulation of histone modifications promotes carcinogenesis by altering transcription. Breast cancers frequently overexpress the histone methyltransferase EZH2, the catalytic subunit of Polycomb Repressor Complex 2 (PRC2). However, the role of EZH2 in this setting is unclear due to the context-dependent functions of PRC2 and the heterogeneity of breast cancer. Moreover, the mechanisms underlying PRC2 overexpression in cancer are obscure. Here, using multiple models of breast cancer driven by the oncogene ErbB2, we show that the tyrosine kinase c-Src links energy sufficiency with PRC2 overexpression via control of mRNA translation. By stimulating mitochondrial ATP production, c-Src suppresses energy stress, permitting sustained activation of the mammalian/mechanistic target of rapamycin complex 1 (mTORC1), which increases the translation of mRNAs encoding the PRC2 subunits Ezh2 and Suz12. We show that Ezh2 overexpression and activity are pivotal in ErbB2-mediated mammary tumourigenesis. These results reveal the hitherto unknown c-Src/mTORC1/PRC2 axis, which is essential for ErbB2-driven carcinogenesis.


Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Epigênese Genética , Complexo Repressor Polycomb 2/genética , Receptor ErbB-2/metabolismo , Quinases da Família src/metabolismo , Trifosfato de Adenosina/metabolismo , Adulto , Animais , Neoplasias da Mama/patologia , Carcinogênese , Linhagem Celular Tumoral , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Feminino , Humanos , Glândulas Mamárias Humanas/metabolismo , Glândulas Mamárias Humanas/patologia , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Camundongos Transgênicos , Pessoa de Meia-Idade , Mitocôndrias/genética , Mitocôndrias/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Biossíntese de Proteínas , Receptor ErbB-2/genética , Quinases da Família src/genética
16.
Parasitol Res ; 118(7): 2203-2211, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31154527

RESUMO

Mitochondrial (mt) DNA has been useful in revealing the phylogenetic relationship of eukaryotic organisms including flatworms. Therefore, the use of mitogenomic data for the comparative and phylogenetic purposes is needed for those families of digenetic trematodes for which the mitogenomic data are still missing. Molecular data with sufficiently rich informative characters that can better resolve species identification, discrimination, and membership in different genera is also required for members of some morphologically difficult families of trematodes bearing few autapomorphic characters among its members. Here, the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) and the complete mt genome of the trematode Uvitellina sp. (Cyclocoelidae: Haematotrephinae) was determined and annotated. The mt genome of this avian trematode is 14,217 bp in length, containing 36 genes plus a single non-coding region. The ITS rDNA sequences were used for the pairwise sequence comparison of Uvitellina sp. with European cyclocoelid species, and the mitochondrial 12 protein-coding genes (PCGs) and two ribosomal RNA genes were used to evaluate the position of the family within selected trematodes. The ITS rDNA analysis of Uvitellina sp. showed less nucleotide differences with Hyptiasmus oculeus (16.77%) than with other European cyclocoelids (18.63-23.58%). The Bayesian inference (BI) analysis using the 12 mt PCGs and two rRNA genes supported the placement of the family Cyclocoelidae within the superfamily Echinostomatoidea (Plagiorchiida: Echinostmata). The availability of the mt genome sequences of Uvitellina sp. provides a novel resource of molecular markers for phylogenetic studies of Cyclocoelidae and other trematodes.


Assuntos
DNA Mitocondrial/genética , Echinostomatidae/genética , Genoma Mitocondrial/genética , Mitocôndrias/genética , Animais , Sequência de Bases , Teorema de Bayes , Aves/parasitologia , DNA Ribossômico/genética , DNA Espaçador Ribossômico/genética , Echinostomatidae/classificação , Filogenia , Análise de Sequência de DNA
17.
DNA Cell Biol ; 38(8): 786-795, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31157984

RESUMO

The ambush hypothesis speculates that off-frame stop codons increase translational efficiency after ribosomal frameshifts by stopping early frameshifted translation. Some evidences fit this hypothesis: (1) synonymous codon usages increase with their potential contribution to off-frame stops; (2) the genetic code assigns frequent amino acids to codon families contributing to off-frame stops; (3) positive biases for off-frame stops (AT rich) occur despite adverse nucleotide (GC) biases; and (4) mitochondrial off-frame stop codon densities increase with ribosomal structural instability, potential proxy of frameshift frequencies. In this study, analyses of vertebrate mitogenes and tRNA synthetase genes from all superkingdoms and viruses test a new prediction of the ambush hypothesis: sequences immediately downstream of frameshift-inducing homopolymer codons (AAA, CCC, GGG, and TTT) are off-frame stop rich. Codons immediately downstream of homopolymer codons form more than average off-frame stops, biases are stronger than for corresponding upstream distances and for any other group of synonymous codons. Sequences downstream of that high-density region are off-frame stop depleted. This decrease suggests that off-frame stops, combined with suppressor tRNAs regulate translation of overlapping coding sequences. Results show the predictive power of the ambush hypothesis, from macroevolutionary (genetic code structure) to detailed gene sequence anatomy.


Assuntos
Códon de Terminação , Código Genético , Mitocôndrias/genética , RNA de Transferência/genética , Animais , Archaea/genética , Bactérias/genética , Códon , Humanos , Camundongos , Fases de Leitura Aberta , Vírus/genética
18.
Nat Cell Biol ; 21(6): 710-720, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31160709

RESUMO

The capacity of stem cells to self-renew or differentiate has been attributed to distinct metabolic states. A genetic screen targeting regulators of mitochondrial dynamics revealed that mitochondrial fusion is required for the maintenance of male germline stem cells (GSCs) in Drosophila melanogaster. Depletion of Mitofusin (dMfn) or Opa1 led to dysfunctional mitochondria, activation of Target of rapamycin (TOR) and a marked accumulation of lipid droplets. Enhancement of lipid utilization by the mitochondria attenuated TOR activation and rescued the loss of GSCs that was caused by inhibition of mitochondrial fusion. Moreover, constitutive activation of the TOR-pathway target and lipogenesis factor Sterol regulatory element binding protein (SREBP) also resulted in GSC loss, whereas inhibition of SREBP rescued GSC loss triggered by depletion of dMfn. Our findings highlight a critical role for mitochondrial fusion and lipid homeostasis in GSC maintenance, providing insight into the potential impact of mitochondrial and metabolic diseases on the function of stem and/or germ cells.


Assuntos
Proteínas de Drosophila/genética , Proteínas de Membrana/genética , Dinâmica Mitocondrial/genética , Células-Tronco/metabolismo , Proteínas de Ligação a Elemento Regulador de Esterol/genética , Animais , Diferenciação Celular/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Homeostase , Metabolismo dos Lipídeos/genética , Masculino , Mitocôndrias/genética , Receptores Proteína Tirosina Quinases/genética , Transdução de Sinais/genética , Nicho de Células-Tronco/genética , Células-Tronco/citologia , Testículo/crescimento & desenvolvimento , Testículo/metabolismo
19.
Environ Pollut ; 252(Pt A): 330-335, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31158661

RESUMO

Aluminum is a widely distributed metal that has been reported to have embryotoxicity and fetotoxicity in animal studies. However, there has been no study of the association between prenatal aluminum exposure and newborn mitochondrial DNA copy number (mtDNAcn). We aimed to investigate the effect of prenatal aluminum exposure on newborn mtDNAcn. A total of 762 mother-newborn pairs were recruited between November 2013 and March 2015 in Wuhan city, China. We measured maternal urinary aluminum concentrations at three trimesters of pregnancy. Relative mtDNAcn was measured in DNA extracted from umbilical cord blood samples. We used generalized estimating equations to assess the relationship between prenatal aluminum exposure and newborn mtDNAcn. The geometric means of creatinine corrected aluminum concentrations were 31.0 µg/g Cr (95% CI: 27.6, 34.7), 40.9 µg/g Cr (95% CI: 35.7, 46.8) and 58.4 µg/g Cr (95% CI: 51.2, 67.4) for the first, second and third trimesters, respectively. After adjustment for potential confounding factors, a doubling of maternal urinary aluminum concentrations during the second and third trimesters was related to 3.16% (95% CI: 0.88, 5.49) and 4.20% (95% CI: 1.64, 6.81) increases in newborn mtDNAcn, respectively, while the association between maternal urinary aluminum concentration during the first trimester and newborn mtDNAcn was not significant (percent difference: 0.70%, 95% CI: -2.25, 3.73). Prenatal aluminum exposure during the second and third trimesters was positively associated with newborn mtDNAcn. Further studies are essential to elucidate on the potential health consequences of newborn mtDNAcn.


Assuntos
Alumínio/toxicidade , Variações do Número de Cópias de DNA/efeitos dos fármacos , DNA Mitocondrial/genética , Exposição Materna/efeitos adversos , Efeitos Tardios da Exposição Pré-Natal/genética , Adulto , Alumínio/urina , China , Cidades , Variações do Número de Cópias de DNA/genética , Feminino , Humanos , Recém-Nascido , Masculino , Mitocôndrias/genética , Gravidez , Primeiro Trimestre da Gravidez
20.
J Dairy Sci ; 102(8): 7576-7582, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202663

RESUMO

During the peripartum period, dairy cows experience both an increase in circulating fatty acid (FA) profile and a change in circulating FA profile, which have been shown to alter regulation of gluconeogenic genes. The objective was to quantify gene expression of key enzymes involved in gluconeogenesis and FA transport into the mitochondria in primary hepatocytes in response to exposure to an FA mixture mimicking what is circulating in a transition dairy cow with or without enrichment of C16:0, C18:0, and C18:1. Primary hepatocytes were isolated from 4 Holstein bull calves 3 d of age (± standard deviation 2 d) and cultured. Twenty-four hours after plating, treatments were applied to the cells for 24-h incubation. Treatments consisted of (1) control (1% BSA), (2) 0.75 mM FA cocktail (3% C14:0, 27% C16:0, 23% C18:0, 31% C18:1, 8% C18:2, and 8% C18:3 to mimic the FA profile of dairy cattle at calving), (3) 0.90 mM FA cocktail, (4) 0.75 mM FA cocktail + 0.15 mM C16:0, (5) 0.75 mM FA cocktail + 0.15 mM C18:0, and (6) 0.75 mM FA cocktail + 0.15 mM C18:1. After harvest in Trizol (Life Technologies, Carlsbad, CA), samples were stored at -80°C until RNA extraction, purification, and reverse transcription. Abundance of mRNA was measured using quantitative real-time PCR. Expression of genes of interest [carnitine palmitoyltransferase 1A, pyruvate carboxylase, cytosolic phosphoenolpyruvate carboxykinase (PCK1), mitochondrial phosphoenolpyruvate carboxykinase, and glucose-6-phosphatase] was calculated relative to the average abundance of 2 reference genes (ribosomal protein L32 and glyceraldehyde 3-phosphate dehydrogenase), which were the most stable out of 3 tested. Data were analyzed using PROC MIXED (SAS version 9.4; SAS Institute, Cary, NC) with the fixed effect of treatment and calf in the random statement. The addition of FA compared with the 1% BSA treatment increased the expression of carnitine palmitoyltransferase 1A and cytosolic PCK1. Enrichment with individual FA did not further regulate pyruvate carboxylase or PCK1 beyond that achieved by the basal profile. These results suggest that shifts in circulating FA profile within a biological range, without a difference in the total FA concentration, have minimal effects on transcriptional regulation of hepatic gluconeogenic genes in primary bovine hepatocytes.


Assuntos
Bovinos/metabolismo , Ácidos Graxos/metabolismo , Gluconeogênese , Hepatócitos/metabolismo , Animais , Bovinos/genética , Células Cultivadas , Feminino , Expressão Gênica , Regulação da Expressão Gênica , Glucose-6-Fosfatase/genética , Glucose-6-Fosfatase/metabolismo , Lactação , Fígado/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Fosfoenolpiruvato Carboxiquinase (ATP)/genética , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Piruvato Carboxilase/genética , Piruvato Carboxilase/metabolismo
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