Downregulation of autophagy‐regulatory proteins contributes to induction of replicative senescence in Hs68 cells

Abstract

Autophagy is reported to be involved in preventing cellular senescence. However, the extent to which autophagy contributes to senescence is presently unclear. Here, we investigated the role of autophagy in replicative senescence using Hs68 human foreskin fibroblasts. Human foreskin fibroblasts, Hs68 cells, at an initial passage of 15 were serially cultured for several months until they reached cellular senescence. Induction of replicative senescence in aged cells (at passage 40) was confirmed by senescence‐associated β‐galactosidase (SA‐β‐gal) activity that represents a sensitive and reliable marker for quantifying senescent cells. The expression level of p53, which is required for induction of senescence, p53 expression continued to increase up to passage 34. Notably, the gradual decrease in basal autophagy coincided with replicative senescence induction as determined by LC3 conversion assay. However, despite decreased basal autophagic activity in senescent cells, autophagy inducers could induce autophagy in senescent cells. RT‐PCR analysis of 11 autophagy‐related genes revealed that the decreased basal autophagy in senescent cells might be due to the downregulation of autophagy‐regulatory proteins, but not autophagy machinery components. Moreover, the senescence phenotype was not induced in the cells in which rapamycin was added to the culture to continuously induce autophagy from passage 29 until passage 40. Together, our findings suggest that reduced basal autophagy levels due to downregulation of autophagy‐regulatory proteins may be the mechanism underlying replicative senescence in Hs68 cells. In addition, alterations in autophagic activity offer an additional target for therapeutics that limit the process of senescence.Support or Funding InformationSupported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2016R1D1A1B03930193)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.