Hypoxia Preserves Chromatin Integrity and Delays Cellular Senescence through Epigenetic Regulation

Physiological and pathological contexts of hypoxiaOxygen concentration in peripheral tissues varies widely, ranging from approximately 0.1% to 8%, depending on the balance between vascular oxygen supply and cellular oxygen consumption.Profoundly hypoxic regions (0.1-1% O₂) are commonly observed in solid tumors as well as in specialized stem cell niches, indicating that hypoxia is not merely a pathological condition but also a physiologically relevant microenvironment (Mohyeldin et al., 2010;Sullivan et al., 2008).Within these contexts, hypoxia profoundly influences cellular fate decisions.In tumors hypoxic cancer cells frequently acquire resistance to chemotherapy and radiotherapy, while stem cells exposed to low oxygen resist differentiation and preferentially maintain stemness.Hypoxia supports a microenvironmental niche that favors quiescent survival under metabolic stress rather than directly inducing therapy-related dormancy.In this context, hypoxia-associated factors such as TGFβ2 and p27Hypoxia is a physiologically relevant microenvironment in both normal and diseased tissues and has emerged as a potent modulator of cellular senescence and organismal longevity.This review synthesizes evidence that hypoxia delays senescence across diverse experimental systems and species, and highlights mechanisms by which hypoxia rewires chromatin states during senescence-associated transitions.We focus on oxygen-and α-ketoglutarate-dependent epigenetic regulators, particularly histone lysine demethylases, whose catalytic activities are limited under hypoxia.Consequently, histone methylation increases and higher-order chromatin organization is stabilized.Using oncogene-induced senescence as an experimentally tractable framework, we discuss recent findings showing that hypoxia suppresses senescence-associated histone clipping, preserves nuclear lamina integrity, and restrains large-scale heterochromatin reorganization while leaving canonical cell-cycle arrest largely intact.We further consider emerging links among DNA damage, epigenetic instability, and aging phenotypes, and propose that senescence can be viewed as a breakdown of coordinated epigenetic homeostasis.By integrating these concepts, we position hypoxia and hypoxia-mimetic interventions as promising strategies to modulate aging-associated cellular states and to explore therapeutic opportunities in age-related pathologies.