Wip1 regulates wound healing by affecting activities of keratinocytes and endothelial cells through ATM-p53 and mTOR signaling

As a p53-regulated gene, Wip1 regulates proliferation, migration, apoptosis, and senescence of several type cells, but its biological functions in keratinocytes and endothelial cells which are involved wound healing are not fully understood. This study aims to reveal the function and underlying mechanism of Wip1 in wound healing using models of transgenic animal, keratinocytes, and endothelial cells. Using Wip1 knockout C57 BL/6 mice, we investigated effect of Wip1 deficiency on wound healing and angiogenesis; And using HaCaT and HUVEC as keratinocytes and endothelial cells, combined using primary keratinocytes from Wip1 knockout mice, we studied the effects of Wip1 knockdown/knockout or overexpression on proliferation, migration, and protein expressions of signaling components in ATM-p53 and mTOR pathway. Wip1 deficiency in mice impaired the wound repair and endothelial angiogenesis, reduced the thickness of granulation tissue, and decreased the number of Ki67-positive cells and CD31 positive vessels in granulation tissue. Knockdown of Wip1 by shRNAs suppressed the proliferation and migration of HaCaT and HUVEC cells and induced notably apoptosis in the two cells. In western blot, Wip1 knockdown enriched p53 and ATM proteins, while decreased activated AKT, mTOR and activated S6 ribosomal protein (pS6) levels in HaCaT and HUVEC cells. Ectopic expression of Wip1 decreased the p53 and ATM proteins, while increased activated AKT, mTOR and pS6 levels in HaCaT and HUVEC cells. And in primary keratinocytes from mice tail skin, Wip1 knockout increased p53 and ATM, while decreased activated AKT, mTOR and pS6 protein levels. Our study directly supports that Wip1 regulated skin wound healing possibly by affecting bioactivities including proliferation, migration and apoptosis of keratinocytes and endothelial cells at least through by modulating ATM-p53 and mTOR signaling.