DNA Polymerase Gamma Acetylation Governs Mitochondrial Homeostasis and Vascular Cell Senescence

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 POLG ^D257A/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 POLG ^D257A/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.

Acetylation; DNA polymerase gamma; human aortic smooth muscle cells; mitochondrial homeostasis; senescence.