bims-mitran 2023-08-06 papers

Issue of 2023–08–06
six papers selected by
Andreas Kohler, University of Graz

Cardiovasc Res. 2023 Jul 31. pii: cvad124. [Epub ahead of print]

FAM210A regulates mitochondrial translation and maintains cardiac mitochondrial homeostasis.

Jiangbin Wu, Kadiam C Venkata Subbaiah, Omar Hedaya, Si Chen, Joshua Munger, Wai Hong Wilson Tang, Chen Yan, Peng Yao.

AIMS: Mitochondria play a vital role in cellular metabolism and energetics and support normal cardiac function. Disrupted mitochondrial function and homeostasis cause a variety of heart diseases. Fam210a (family with sequence similarity 210 member A), a novel mitochondrial gene, is identified as a hub gene in mouse cardiac remodeling by multi-omics studies. Human FAM210A mutations are associated with sarcopenia. However, the physiological role and molecular function of FAM210A remain elusive in the heart. We aim to determine the biological role and molecular mechanism of FAM210A in regulating mitochondrial function and cardiac health in vivo.
METHODS AND RESULTS: Tamoxifen-induced αMHCMCM-driven conditional knockout of Fam210a in the mouse cardiomyocytes induced progressive dilated cardiomyopathy and heart failure, ultimately causing mortality. Fam210a deficient cardiomyocytes exhibit severe mitochondrial morphological disruption and functional decline accompanied by myofilament disarray at the late stage of cardiomyopathy. Furthermore, we observed increased mitochondrial reactive oxygen species production, disturbed mitochondrial membrane potential, and reduced respiratory activity in cardiomyocytes at the early stage before contractile dysfunction and heart failure. Multi-omics analyses indicate that FAM210A deficiency persistently activates integrated stress response (ISR), resulting in transcriptomic, translatomic, proteomic, and metabolomic reprogramming, ultimately leading to pathogenic progression of heart failure. Mechanistically, mitochondrial polysome profiling analysis shows that FAM210A loss of function compromises mitochondrial mRNA translation and leads to reduced mitochondrial encoded proteins, followed by disrupted proteostasis. We observed decreased FAM210A protein expression in human ischemic heart failure and mouse myocardial infarction tissue samples. To further corroborate FAM210A function in the heart, AAV9-mediated overexpression of FAM210A promotes mitochondrial-encoded protein expression, improves cardiac mitochondrial function, and partially rescues murine hearts from cardiac remodeling and damage in ischemia-induced heart failure.
CONCLUSION: These results suggest that FAM210A is a mitochondrial translation regulator to maintain mitochondrial homeostasis and normal cardiomyocyte contractile function. This study also offers a new therapeutic target for treating ischemic heart disease.

Keywords: FAM210A; cardiomyopathy; heart failure; integrated stress response; mRNA translation; metabolism; mitochondria; myocardial infarction

DOI: https://doi.org/10.1093/cvr/cvad124

iScience. 2023 Jul 21. 26(7): 107180

Contact sites between endoplasmic reticulum sheets and mitochondria regulate mitochondrial DNA replication and segregation.

Hema Saranya Ilamathi, Sara Benhammouda, Amel Lounas, Khalid Al-Naemi, Justine Desrochers-Goyette, Matthew A Lines, François J Richard, Jackie Vogel, Marc Germain.

Mitochondria are multifaceted organelles crucial for cellular homeostasis that contain their own genome. Mitochondrial DNA (mtDNA) replication is a spatially regulated process essential for the maintenance of mitochondrial function, its defect causing mitochondrial diseases. mtDNA replication occurs at endoplasmic reticulum (ER)-mitochondria contact sites and is affected by mitochondrial dynamics: The absence of mitochondrial fusion is associated with mtDNA depletion whereas loss of mitochondrial fission causes the aggregation of mtDNA within abnormal structures termed mitobulbs. Here, we show that contact sites between mitochondria and ER sheets, the ER structure associated with protein synthesis, regulate mtDNA replication and distribution within mitochondrial networks. DRP1 loss or mutation leads to modified ER sheets and alters the interaction between ER sheets and mitochondria, disrupting RRBP1-SYNJ2BP interaction. Importantly, mtDNA distribution and replication were rescued by promoting ER sheets-mitochondria contact sites. Our work identifies the role of ER sheet-mitochondria contact sites in regulating mtDNA replication and distribution.

Keywords: Biochemistry; Biological sciences; Cell biology

DOI: https://doi.org/10.1016/j.isci.2023.107180

Mol Neurobiol. 2023 Jul 31.

Plausible Role of Mitochondrial DNA Copy Number in Neurodegeneration-a Need for Therapeutic Approach in Parkinson's Disease (PD).

Dhivya Venkatesan, Mahalaxmi Iyer, Arul Narayanasamy, Abilash Valsala Gopalakrishnan, Balachandar Vellingiri.

Parkinson's disease (PD) is an advancing age-associated progressive brain disorder which has various diverse factors, among them mitochondrial dysfunction involves in dopaminergic (DA) degeneration. Aging causes a rise in mitochondrial abnormalities which leads to structural and functional modifications in neuronal activity and cell death in PD. This ends in deterioration of mitochondrial function, mitochondrial alterations, mitochondrial DNA copy number (mtDNA CN) and oxidative phosphorylation (OXPHOS) capacity. mtDNA levels or mtDNA CN in PD have reported that mtDNA depletion would be a predisposing factor in PD pathogenesis. To maintain the mtDNA levels, therapeutic approaches have been focused on mitochondrial biogenesis in PD. The depletion of mtDNA levels in PD can be influenced by autophagic dysregulation, apoptosis, neuroinflammation, oxidative stress, sirtuins, and calcium homeostasis. The current review describes the regulation of mtDNA levels and discusses the plausible molecular pathways in mtDNA CN depletion in PD pathogenesis. We conclude by suggesting further research on mtDNA depletion which might show a promising effect in predicting and diagnosing PD.

Keywords: Copy number; Mitochondrial DNA; Molecular pathways; Parkinson’s disease; TFAM; Therapeutic strategies

DOI: https://doi.org/10.1007/s12035-023-03500-x

Front Cardiovasc Med. 2023 ;10 1204483

Mitochondrial epigenetics in aging and cardiovascular diseases.

Alessia Mongelli, Alessandro Mengozzi, Martin Geiger, Era Gorica, Shafeeq Ahmed Mohammed, Francesco Paneni, Frank Ruschitzka, Sarah Costantino.

Mitochondria are cellular organelles which generate adenosine triphosphate (ATP) molecules for the maintenance of cellular energy through the oxidative phosphorylation. They also regulate a variety of cellular processes including apoptosis and metabolism. Of interest, the inner part of mitochondria-the mitochondrial matrix-contains a circular molecule of DNA (mtDNA) characterised by its own transcriptional machinery. As with genomic DNA, mtDNA may also undergo nucleotide mutations that have been shown to be responsible for mitochondrial dysfunction. During physiological aging, the mitochondrial membrane potential declines and associates with enhanced mitophagy to avoid the accumulation of damaged organelles. Moreover, if the dysfunctional mitochondria are not properly cleared, this could lead to cellular dysfunction and subsequent development of several comorbidities such as cardiovascular diseases (CVDs), diabetes, respiratory and cardiovascular diseases as well as inflammatory disorders and psychiatric diseases. As reported for genomic DNA, mtDNA is also amenable to chemical modifications, namely DNA methylation. Changes in mtDNA methylation have shown to be associated with altered transcriptional programs and mitochondrial dysfunction during aging. In addition, other epigenetic signals have been observed in mitochondria, in particular the interaction between mtDNA methylation and non-coding RNAs. Mitoepigenetic modifications are also involved in the pathogenesis of CVDs where oxygen chain disruption, mitochondrial fission, and ROS formation alter cardiac energy metabolism leading to hypertrophy, hypertension, heart failure and ischemia/reperfusion injury. In the present review, we summarize current evidence on the growing importance of epigenetic changes as modulator of mitochondrial function in aging. A better understanding of the mitochondrial epigenetic landscape may pave the way for personalized therapies to prevent age-related diseases.

Keywords: aging; cardiovascular diseases; methylation; mitochondria; mitoepigenetics; mtDNA; ncRNAs

DOI: https://doi.org/10.3389/fcvm.2023.1204483

Chem Commun (Camb). 2023 Aug 04.

A water-soluble fluorescent organic nano-photosensitizer for the ratiometric detection of mitochondrial G-quadruplexes with photodynamic therapy potential.

Qing-Yu Ma, Xiang Li, Wei Zhou, Xia-Fen Li, Yi-Chen Liu, Gai-Li Feng, Hongwei Tan, Yuan Zhang, Guo-Wen Xing.

We report a water-soluble AIEgen (TPAL) that can self-assemble into fluorescent organic nanoparticles for the ratiometric detection of mitochondrial DNA (mtDNA) parallel G-quadruplexes (G4s) with high selectivity, a low detection limit and photodynamic therapy (PDT) potential.

DOI: https://doi.org/10.1039/d3cc02788k

FEBS J. 2023 Aug 01.

CUL3 induces mitochondrial dysfunction via MRPL12 ubiquitination in renal tubular epithelial cells.

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease worldwide and the strongest predictor of mortality in patients with diabetes. Despite its significance, the pathological mechanism underlying the onset and progression of DKD remains incompletely understood. In this study, we have shown that mitochondrial ribosomal protein L12 (MRPL12) plays a significant role in DKD by modulating mitochondrial function. We demonstrated that MRPL12 was mainly ubiquitinated at K150 in renal tubular epithelial cells. We have found that Cullin3 (CUL3), an E3 ubiquitin ligase, directly interacts with MRPL12 and induces the K63-linked ubiquitination of MRPL12, resulting in mitochondrial biosynthesis dysfunction. Moreover, under high glucose conditions in renal tubular epithelial cells, we observed up-regulation of CUL3 expression, significant increase in CUL3-mediated ubiquitination of MRPL12, and dysregulation of mitochondrial biosynthesis. Notably, CUL3 knockdown stabilized the MRPL12 protein and protected mitochondrial biosynthesis under high glucose conditions. Our findings provide novel insight into how CUL3 affects mitochondrial biosynthesis in renal tubular epithelial cells through MRPL12 ubiquitination and suggest a potential therapeutic strategy for DKD in the future.

Keywords: Cullin3; Diabetic kidney disease; MRPL12; Mitochondrial dysfunction

DOI: https://doi.org/10.1111/febs.16919