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Hussain M, Mohammed A, Saifi S, Priya S, Sengupta S. Hyperubiquitylation of DNA helicase RECQL4 by E3 ligase MITOL prevents mitochondrial entry and potentiates mitophagy. J Biol Chem 2023; 299:105087. [PMID: 37495109 PMCID: PMC10470078 DOI: 10.1016/j.jbc.2023.105087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/10/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023] Open
Abstract
Mutations in the DNA helicase RECQL4 lead to Rothmund-Thomson syndrome (RTS), a disorder characterized by mitochondrial dysfunctions, premature aging, and genomic instability. However, the mechanisms by which these mutations lead to pathology are unclear. Here we report that RECQL4 is ubiquitylated by a mitochondrial E3 ligase, MITOL, at two lysine residues (K1101, K1154) via K6 linkage. This ubiquitylation hampers the interaction of RECQL4 with mitochondrial importer Tom20, thereby restricting its own entry into mitochondria. We show the RECQL4 2K mutant (where both K1101 and K1154 are mutated) has increased entry into mitochondria and demonstrates enhanced mitochondrial DNA (mtDNA) replication. We observed that the three tested RTS patient mutants were unable to enter the mitochondria and showed decreased mtDNA replication. Furthermore, we found that RECQL4 in RTS patient mutants are hyperubiquitylated by MITOL and form insoluble aggregate-like structures on the outer mitochondrial surface. However, depletion of MITOL allows RECQL4 expressed in these RTS mutants to enter mitochondria and rescue mtDNA replication. Finally, we show increased accumulation of hyperubiquitylated RECQL4 outside the mitochondria leads to the cells being potentiated to increased mitophagy. Hence, we conclude regulating the turnover of RECQL4 by MITOL may have a therapeutic effect in patients with RTS.
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Affiliation(s)
- Mansoor Hussain
- Signal Transduction Laboratory, National Institute of Immunology, New Delhi, India
| | - Aftab Mohammed
- Signal Transduction Laboratory, National Institute of Immunology, New Delhi, India
| | - Shabnam Saifi
- Signal Transduction Laboratory, National Institute of Immunology, New Delhi, India
| | - Swati Priya
- Signal Transduction Laboratory, National Institute of Immunology, New Delhi, India
| | - Sagar Sengupta
- Signal Transduction Laboratory, National Institute of Immunology, New Delhi, India; National Institute of Biomedical Genomics, Kalyani, India.
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Sarfallah A, Zamudio-Ochoa A, Anikin M, Temiakov D. Mechanism of transcription initiation and primer generation at the mitochondrial replication origin OriL. EMBO J 2021; 40:e107988. [PMID: 34423452 DOI: 10.15252/embj.2021107988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 07/19/2021] [Accepted: 07/27/2021] [Indexed: 11/09/2022] Open
Abstract
The intricate process of human mtDNA replication requires the coordinated action of both transcription and replication machineries. Transcription and replication events at the lagging strand of mtDNA prompt the formation of a stem-loop structure (OriL) and the synthesis of a ∼25 nt RNA primer by mitochondrial RNA polymerase (mtRNAP). The mechanisms by which mtRNAP recognizes OriL, initiates transcription, and transfers the primer to the replisome are poorly understood. We found that transcription initiation at OriL involves slippage of the nascent transcript. The transcript slippage is essential for initiation complex stability and its ability to translocate the mitochondrial DNA polymerase gamma, PolG, which pre-binds to OriL, downstream of the replication origin thus allowing for the primer synthesis. Our data suggest the primosome assembly at OriL-a complex of mtRNAP and PolG-can efficiently generate the primer, transfer it to the replisome, and protect it from degradation by mitochondrial endonucleases.
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Affiliation(s)
- Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Angelica Zamudio-Ochoa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael Anikin
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Hao Z, Wu T, Cui X, Zhu P, Tan C, Dou X, Hsu KW, Lin YT, Peng PH, Zhang LS, Gao Y, Hu L, Sun HL, Zhu A, Liu J, Wu KJ, He C. N 6-Deoxyadenosine Methylation in Mammalian Mitochondrial DNA. Mol Cell 2020; 78:382-395.e8. [PMID: 32183942 DOI: 10.1016/j.molcel.2020.02.018] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 02/03/2020] [Accepted: 02/20/2020] [Indexed: 12/12/2022]
Abstract
N6-Methyldeoxyadenosine (6mA) has recently been shown to exist and play regulatory roles in eukaryotic genomic DNA (gDNA). However, the biological functions of 6mA in mammals have yet to be adequately explored, largely due to its low abundance in most mammalian genomes. Here, we report that mammalian mitochondrial DNA (mtDNA) is enriched for 6mA. The level of 6mA in HepG2 mtDNA is at least 1,300-fold higher than that in gDNA under normal growth conditions, corresponding to approximately four 6mA modifications on each mtDNA molecule. METTL4, a putative mammalian methyltransferase, can mediate mtDNA 6mA methylation, which contributes to attenuated mtDNA transcription and a reduced mtDNA copy number. Mechanistically, the presence of 6mA could repress DNA binding and bending by mitochondrial transcription factor (TFAM). Under hypoxia, the 6mA level in mtDNA could be further elevated, suggesting regulatory roles for 6mA in mitochondrial stress response. Our study reveals DNA 6mA as a regulatory mark in mammalian mtDNA.
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Affiliation(s)
- Ziyang Hao
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Tong Wu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Xiaolong Cui
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Pingping Zhu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; School of Life Science, Zhengzhou University, Zhengzhou 450001, China
| | - Caiping Tan
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Xiaoyang Dou
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Kai-Wen Hsu
- Cancer Genome Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan 333, Taiwan
| | - Yueh-Te Lin
- Cancer Genome Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan 333, Taiwan
| | - Pei-Hua Peng
- Cancer Genome Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan 333, Taiwan
| | - Li-Sheng Zhang
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Yawei Gao
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA; Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Lulu Hu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Hui-Lung Sun
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Allen Zhu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Jianzhao Liu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA
| | - Kou-Juey Wu
- Cancer Genome Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan 333, Taiwan
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Howard Hughes Medical Institute, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA.
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Fujisawa Y, Napoli E, Wong S, Song G, Yamaguchi R, Matsui T, Nagasaki K, Ogata T, Giulivi C. Impact of a novel homozygous mutation in nicotinamide nucleotide transhydrogenase on mitochondrial DNA integrity in a case of familial glucocorticoid deficiency. BBA Clin 2015; 3:70-78. [PMID: 26309815 PMCID: PMC4545511 DOI: 10.1016/j.bbacli.2014.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Familial Glucocorticoid Deficiency (FGD) is a rare autosomal recessive disorder that is characterized by isolated glucocorticoid deficiency. Recently, mutations in the gene encoding for the mitochondrial nicotinamide nucleotide transhydrogenase (NNT) have been identified as a causative gene for FGD; however, no NNT activities have been reported in FGD patients carrying NNT mutations. METHODS Clinical, biochemical and molecular analyses of lymphocytes from FDG homozygous and heterozygous carriers for the F215S NNT mutation. RESULTS In this study, we described an FGD-affected Japanese patient carrying a novel NNT homozygous mutation (c.644T>C; F215S) with a significant loss-of-function (NNT activity = 31% of healthy controls) in peripheral blood cells' mitochondria. The NNT activities of the parents, heterozygous for the mutation, were 61% of controls. CONCLUSIONS Our results indicated that (i) mitochondrial biogenesis (citrate synthase activity) and/or mtDNA replication (mtDNA copy number) were affected at ≤60% NNT activity because these parameters were affected in individuals carrying either one or both mutated alleles; and (ii) other outcomes (mtDNA deletions, protein tyrosine nitration, OXPHOS capacity) were affected at ≤30% NNT activity as also observed in murine cerebellar mitochondria from C57BL/6J (NNT-/-) vs. C57BL/6JN (NNT+/+) substrains. GENERAL SIGNIFICANCE By studying a family affected with a novel point mutation in the NNT gene, a gene-dose response was found for various mitochondrial outcomes providing for novel insights into the role of NNT in the maintenance of mtDNA integrity beyond that described for preventing oxidative stress.
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Affiliation(s)
- Yasuko Fujisawa
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Eleonora Napoli
- Department of Molecular Biosciences, University of California Davis, Davis, CA 95616, USA
| | - Sarah Wong
- Department of Molecular Biosciences, University of California Davis, Davis, CA 95616, USA
| | - Gyu Song
- Department of Molecular Biosciences, University of California Davis, Davis, CA 95616, USA
| | - Rie Yamaguchi
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Toshiharu Matsui
- Department of Pediatrics, Nagaoka Chuo General Hospital, Nagaoka 940-8653, Japan
| | - Keisuke Nagasaki
- Division of Pediatrics, Niigata University Graduate School of Medicine and Dental Sciences, Niigata 951-8122, Japan
| | - Tsutomu Ogata
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Cecilia Giulivi
- Department of Molecular Biosciences, University of California Davis, Davis, CA 95616, USA ; Medical Investigations of Neurodevelopmental Disorders (M. I. N. D.) Institute, University of California Davis, Sacramento, CA 95616
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