A progressive reduction in autophagic capacity contributes to induction of replicative senescence in Hs68 cells |
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| Affiliation: | 1. Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, 57 Shevchenka str., Ivano-Frankivsk 76018, Ukraine;2. Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada;3. DKFZ/ZMBH Alliance, University of Heidelberg, Im Neuenheimer Feld 282, Heidelberg, 69120, Germany;1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, PR China;2. University of Chinese Academy of Sciences, Beijing 100039, PR China;3. Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, PR China;1. Department of Biology, 1 UNF Drive, Univ. of North Florida, Jacksonville, FL 32224, USA;2. Department of Biological Sciences, St. Mary’s University, San Antonio, TX 78228, USA;3. Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA;4. Department of Entomology, University of Arizona, Tucson, AZ 85721, USA;5. Department of Entomology & Nematology, University of Florida, Gainesville, FL 32611, USA |
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| Abstract: | Autophagy has been implicated in delayed aging and extended longevity. Here, we aimed to study the possible effects of autophagy during the progression of replicative senescence, which is one of the major features of aging. Human foreskin fibroblasts, Hs68 cells, at an initial passage of 15 were serially cultured for several months until they reached cellular senescence. A decrease in cell proliferation was observed during the progression of 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. We detected a significantly increased percentage (%) of SA-β-gal-positive cells at passage 40 (63%) when compared with the younger SA-β-gal-positive cells at passage 15 (0.5%). Notably, the gradual decrease in basal autophagy coincided with replicative senescence induction. 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. |
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| Keywords: | Autophagy Replicative senescence Aging Hs68 Rapamycin |
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