DNA Polymerase Gamma Acetylation Governs Mitochondrial Homeostasis and Vascular Cell Senescence

TL;DR

This study reveals how acetylation of DNA polymerase gamma affects mitochondrial function and aging in vascular cells.

Contribution

The discovery of K1039 as a novel acetylation site in Polγ that regulates mitochondrial homeostasis and vascular cell senescence.

Findings

Hyperacetylation of Polγ at K1039 disrupts mtDNA binding and causes mitochondrial dysfunction.

D257A mutation reduces Sirt3-Polγ complex formation, leading to accelerated senescence.

Polγ acetylation at K1039 acts as a molecular switch coordinating mtDNA homeostasis and aging.

Abstract

DNA polymerase gamma (Polγ), the sole polymerase for mitochondrial DNA (mtDNA), emerges as a critical regulator of metabolism-associated senescence. While lysine acetylation represents a key post-translational modification (PTM) influencing mitochondrial function, its mechanistic role in Polγ-mediated vascular aging remains undefined. Through combinatorial approaches employing in vitro acetylation models and POLGD257A/D257A mice, a validated model of mitochondrial dysfunction and senescence, we identify Lys 1039 (K1039) as a novel acetylation site which was dynamically regulated during aging process. Both D257A mutation-driven hyper-acetylation of Polγ K1039 reduced human aortic smooth muscle cell (HASMC) contractility, triggering pathological hyperproliferation and mitochondrial dysfunction, collectively culminating in premature cellular senescence. Pathological stimulation or genetic manipulation inducing hyperacetylation at K1039 disrupts Polγ's binding capacity with mtDNA. This molecular deficiency manifested functionally as compromised contractile performance in HASMCs and accelerated senescence phenotypes. Based on the above foundation and POLGD257A/D257A mice model, we demonstrated that D257A mutation reduced Sirt3-Polγ complex formation constituted the pathologically relevant molecular pathway driving aberrant acetylation homeostasis and leading to the senescence. Our findings establish a previously unrecognized regulatory axis wherein Polγ acetylation status at K1039 serves as a molecular switch coordinating mtDNA homeostasis, HASMCs functionality, and senescence progression. This mechanism might explain the remarkably consistent phenotypic manifestations of Polγ-induced dysfunction across diverse tissues and aging models. This work provides fundamental insights into the epigenetic-metabolic crosstalk governing vascular aging processes, providing a unifying framework for age-related vascular pathologies.

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