Calmodulin-like skin protein suppresses the increase in senescence-associated β-galactosidase induced by hydrogen peroxide or ultraviolet irradiation in keratinocytes.

Calmodulin-like skin protein (CLSP) is a secreted peptide that is produced by skin keratinocytes and some related epithelial cells. It has previously been shown that CLSP is recruited via the bloodstream into the central nervous system where it likely exerts a neuroprotective effect against toxicity related to Alzheimer's disease (AD) by binding to the heterotrimeric humanin receptor and activating intracellular survival signaling. However, it remains to be elucidated whether secreted CLSP shows a protective effect in the skin tissues. In the current study, using primary keratinocytes treated with hydrogen peroxide (H O ) or exposed to ultraviolet (UV) irradiation as senescence models of keratinocytes, we addressed whether CLSP affects senescence in skin keratinocytes. We found that CLSP expression was upregulated by H O or UV in keratinocytes. Furthermore, co-incubation with recombinant CLSP reduced the increase in senescence-associated β-galactosidase-positivity in keratinocytes that were induced by H O or UV. These results suggest that CLSP may function as a senescence-suppressing factor in keratinocytes.