Mechanistic Study of Hypoxia-Mediated Regulation of Osteoblast Senescence via ATP6V1A-Dependent Modulation of...

Osteoblast senescence constitutes one of the major mechanisms in bone degeneration and is under tight regulation by metabolism and oxidative stress. While hypoxia has recently emerged as an important microenvironmental factor influencing the function of bone cells, its role in osteoblast senescence and metabolic regulation has yet to be defined.

The present work entails hypoxia-modulated osteoblast senescence at one level, transcriptomic and metabolomic sequencing, and two levels, in vitro MC3T3-E1 and in vivo AAV-shAtp6v1a mouse models. In transcriptome profiling, hypoxia-responsive genes were identified, whereas non-targeted metabolomics was used to uncover metabolic alterations induced by ATP6V1A knockdown. Oxidative stress and mitochondrial function were assessed by qRT-PCR, Western blotting, SA-β-Gal staining, ROS detection, JC-1 mitochondrial potential, and immunofluorescence. Micro-CT, H&E, Masson, and immunohistochemistry studies were performed to investigate bone structure and protein expression in vivo.

Hypoxia markedly mitigated osteoblast senescence, decreasing p53 and p21 expressions and the number of SA-β-Gal-positive cells. It reduced intracellular ROS levels and increased HK2 and LDH expression, decreased ATP, and increased lactate, hinting at a shift toward glycolysis. Transcriptome analysis identified ATP6V1A as one of the major hypoxia-downregulated genes. Knockdown of ATP6V1A reduced ROS levels, inhibited p21 expression, improved mitochondrial function. Metabolomics disclosed remapping pathways in glycolysis, lipid, and amino acid metabolism.

This study identifies a "Hypoxia-ATP6V1A-Oxidative Stress-Metabolic Remodeling-Anti-Senescence" axis, demonstrating that hypoxia delays osteoblast senescence by downregulating ATP6V1A, suppressing oxidative stress, and reprogramming metabolism, providing new insights and potential therapeutic targets for bone degenerative diseases.