Senescence-associated HSP60 expression in normal human skin fibroblasts

Normal mammalian fibroblasts cultured in vitro undergo a limited number of divisions before entering a senescent phase in which they can be maintained for long periods but cannot be induced to divide. Senescent cells become unresponsive to growth-promoting signals and exhibit senescent cell morphology with flattened and enlarged cell shape. Several chaperones have a direct effect on cellular senescence. HSP60 has been largely studied in our laboratories and it has been associated with uncontrolled cell proliferation in tumor cells. Since senescence is firmly regulated during cell cycle progression, we wanted to investigate HSP60 protein level during cellular senescence. Our data show that HSP60 increases during the initial stage of senescence and that it is localized in cellular compartments, resembling mitochondria. An increase in HSP60 protein amount is associated with a cell cycle slow-down and it may have a role in cell cycle progression.