p16INK4a Aging

p16INK4a aging refers to increased expression of the cell cycle inhibitor p16INK4a as organisms age. p16INK4a plays a critical role in enforcing cell cycle arrest by inhibiting cyclin-dependent kinases, thereby preventing proliferation of damaged cells. With aging, p16INK4a expression rises in multiple tissues, reflecting accumulated cellular stress, DNA damage, and telomere dysfunction. Elevated p16INK4a is widely used as a biomarker of cellular senescence and biological aging. While p16INK4a activation protects against uncontrolled cell division and cancer, its persistent expression reduces tissue regenerative capacity by limiting stem cell proliferation. Increased p16INK4a contributes to stem cell exhaustion, impaired tissue repair, and functional decline. Understanding p16INK4a aging highlights the balance between tumor suppression and regenerative aging and provides insight into how senescence pathways influence organismal aging.