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Sillamaa S, Piljukov VJ, Vaask I, Sedman T, Jõers P, Sedman J. UvrD-like helicase Hmi1 Has an ATP independent role in yeast mitochondrial DNA maintenance. DNA Repair (Amst) 2023; 132:103582. [PMID: 37839213 DOI: 10.1016/j.dnarep.2023.103582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/17/2023]
Abstract
Hmi1 is a UvrD-like DNA helicase required for the maintenance of the yeast Saccharomyces cerevisiae mitochondrial DNA (mtDNA). Deletion of the HMI1 ORF leads to the formation of respiration-deficient petite mutants, which either contain a short fragment of mtDNA arranged in tandem repeats or lack mtDNA completely. Here we characterize point mutants of the helicase designed to target the ATPase or ssDNA binding activity and show that these mutations do not separately lead to complete loss of the Hmi1 function. The mutant strains support ATP production via oxidative phosphorylation and enable us to directly analyze the impact of both activities on the stability of wild-type mtDNA in this petite-positive yeast. Our data reveal that Hmi1 mutants affecting ssDNA binding display a stronger defect in the maintenance of mtDNA compared to the mutants of ATP binding/hydrolysis. Hmi1 mutants impaired in ssDNA binding demonstrate sensitivity to UV irradiation and lower levels of Cox2 encoded by the mitochondrial genome. This suggests a complex and multifarious role for Hmi1 in mtDNA maintenance-linked transactions, some of which do not require the ATP-dependent helicase activity.
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Affiliation(s)
- Sirelin Sillamaa
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Vlad-Julian Piljukov
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Iris Vaask
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Tiina Sedman
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Priit Jõers
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| | - Juhan Sedman
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
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Wang Y, Wang X, Long Q, Liu Y, Yin T, Sirota I, Ren F, Gu Z, Luo J. Reducing embryonic mtDNA copy number alters epigenetic profile of key hepatic lipolytic genes and causes abnormal lipid accumulation in adult mice. FEBS J 2021; 288:6828-6843. [PMID: 34258867 DOI: 10.1111/febs.16121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/30/2021] [Accepted: 07/13/2021] [Indexed: 12/17/2022]
Abstract
Adverse fetal environment, in particular a shortage or excess of nutrients, is associated with increased risks of metabolic diseases later in life. However, the molecular mechanisms underlying this developmental origin of adult diseases remain unclear. Here, we directly tested the role of mitochondrial stress in mediating fetal programming in mice by enzymatically depleting mtDNA in zygotes. mtDNA-targeted plasmid microinjection is used to reduce embryonic mtDNA copy number directly, followed by embryo transfer. Mice with reduced zygote mtDNA copy number were born morphologically normal and showed no accelerated body weight gain. However, at 5 months of age these mice showed markedly increased hepatic lipidosis and became glucose-intolerant. Hepatic mRNA and protein expressions of peroxisome proliferator-activated receptor α (Pparα), a key transcriptional regulator of lipid metabolism, were significantly decreased as a result of increased DNA methylation in its proximal regulatory region. These results indicate that perturbation of mitochondrial function around the periconceptional period causes hypermethylation and thus suppressed expression of PPARα in fetal liver, leading to impaired hepatic lipid metabolism. Our findings provide the first direct evidence that mitochondrial stress mediates epigenetic changes associated with fetal programming of adult diseases in a mammalian system.
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Affiliation(s)
- Yakun Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Xuan Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Qiaoming Long
- Cam-Su Mouse Genomic Resource Center, Soochow University, China
| | - Yuanwu Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Tao Yin
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Inna Sirota
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA
| | - Fazheng Ren
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
| | - Zhenglong Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA
| | - Junjie Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, China
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Yalgin C, Rovenko B, Andjelković A, Neefjes M, Oymak B, Dufour E, Hietakangas V, Jacobs HT. Effects on Dopaminergic Neurons Are Secondary in COX-Deficient Locomotor Dysfunction in Drosophila. iScience 2020; 23:101362. [PMID: 32738610 PMCID: PMC7394922 DOI: 10.1016/j.isci.2020.101362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/15/2020] [Accepted: 07/08/2020] [Indexed: 12/31/2022] Open
Abstract
Dopaminergic (DA) neurons have been implicated as key targets in neurological disorders, notably those involving locomotor impairment, and are considered to be highly vulnerable to mitochondrial dysfunction, a common feature of such diseases. Here we investigated a Drosophila model of locomotor disorders in which functional impairment is brought about by pan-neuronal RNAi knockdown of subunit COX7A of cytochrome oxidase (COX). Despite minimal neuronal loss by apoptosis, the expression and activity of tyrosine hydroxylase was decreased by half. Surprisingly, COX7A knockdown specifically targeted to DA neurons did not produce locomotor defect. Instead, using various drivers, we found that COX7A knockdown in specific groups of cholinergic and glutamatergic neurons underlay the phenotype. Based on our main finding, the vulnerability of DA neurons to mitochondrial dysfunction as a cause of impaired locomotion in other organisms, including mammals, warrants detailed investigation.
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Affiliation(s)
- Cagri Yalgin
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland; Institute of Biotechnology, FI-00014 University of Helsinki, Finland
| | - Bohdana Rovenko
- Institute of Biotechnology, FI-00014 University of Helsinki, Finland; Faculty of Biological and Environmental Sciences, FI-00014 University of Helsinki, Finland
| | - Ana Andjelković
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| | - Margot Neefjes
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland; Institute of Biotechnology, FI-00014 University of Helsinki, Finland
| | - Burak Oymak
- Institute of Biotechnology, FI-00014 University of Helsinki, Finland
| | - Eric Dufour
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| | - Ville Hietakangas
- Institute of Biotechnology, FI-00014 University of Helsinki, Finland; Faculty of Biological and Environmental Sciences, FI-00014 University of Helsinki, Finland
| | - Howard T Jacobs
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland.
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