GSE108081
A role for Pak2 kinase in cellular senescence and organismal aging
Cellular senescence is an irreversible cell growth arrest state linked to loss of tissue function and aging in mammals. The cellular transition from proliferation to senescence is marked by increased expression of the cell-cycle inhibitor p16INK4A and formation of senescence-associated heterochromatin foci (SAHF). It is known that SAHF formation depends primarily on HIRA-mediated nucleosome assembly of H3.3, and that the serine/threonine protein kinase Pak2 regulates HIRA-mediated nucleosome assembly of histone H3.3. Here, we tested the role of Pak2 in the regulation of cellular senescence. Depletion of Pak2 delays premature cellular senescence in both oncogene-induced senescence in human fibroblasts IMR90 cells and in oxidative stress induced senescence of mouse embryonic fibroblasts. Furthermore, overexpression of Pak2 promotes senescence of IMR90 cells. Importantly, depletion of Pak2 in mice delays the onset of some of the aging-associated phenotypes and extend life span of a progeroid mouse model. Lastly, we showed that Pak2 is required for expression of a group of genes involved in cellular senescence and regulates the deposition of newly synthesized H3.3 onto chromatin in senescent cells. Together, our results demonstrate that Pak2 is an important regulator of cellular senescence and organismal aging, in part through the regulation of gene expression and H3.3 nucleosome assembly. Overall design: To understand the impact of Pak2 on senescence, we performed RNA-seq analysis on wild type Pak2 MEFs and Pak2H/H MEFs at two different time points, P3 and P7, representing the proliferating and senescent states of WT MEF cells, respectively .