Abstract 893: The cofilin-TEAD1-p27Kip1 pathway ablates cell senescence

Abstract

Abstract Morphological change is an explicit characteristic of cell senescence, but the underlying mechanisms remain to be addressed. Here we demonstrated, after a survey of various actin-binding proteins, that up-regulation of cofilin-1 was essential for the reduced rate of actin depolymerization in senescent cells, as well as their morphological enlargement . Additionally, the up-regulated cofilin-1 mainly existed in the serine-3 phosphorylated form according to the 2D gel immunoblotting assay. Accumulation of cofilin-1 in senescent cells depended on the post-translational mechanism, as the ubiquitin-proteasomal degradation of cofilin-1 was reduced without any change in mRNA level. Up-regulation of cofilin-1 was not only found in replicative senescence but also in oxidative stress- and K-Ras oncogene-induced senescence. Over-expression of wild-type cofilin-1 and constitutively phosphorylated cofilin-1 promoted cell senescence with increased cell size. Additionally, senescent phenotypes were reduced by knockdown of total cofilin-1. The senescence induced by over-expression of cofilin-1 was dependent on p27Kip1 but not p53 and p16INK4 expression. Knockdown of p27Kip1 alleviated cell senescence induced by oxidative stress or replicative stress. We also found that over-expression of cofilin-1 induced expression of p27Kip1 through transcriptional suppression of the TEAD1 transcription factor. The TEAD1 transcription factor played a transrepressive role on the p27Kip1 gene promoter as determined by the promoter deletion reporter gene assay. Interestingly, TEAD1 down-regulation was accompanied by up-regulation of cofilin-1 in senescence. Knockdown and restoration of TEAD1 in young cells and old cells could induce and inhibit p27Kip1 and cell senescence, respectively. Furthermore, senescence induced by the over-expression of cofilin-1 could be alleviated by ectopic expression of TEAD1. Taken together, current data suggest that cofilin-1/TEAD1/p27Kip1 signaling is involved in senescence-related morphological change and growth arrest. Keywords: Cofilin-1, TEAD1, p27Kip1, morphology, growth arrest, senescence Citation Format: Yi-Jang Lee, Cheng-Han Tsai, Chun-Yuan Chang. The cofilin-TEAD1-p27Kip1 pathway ablates cell senescence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 893.