title: Sirt1 attenuates camptothecin-induced apoptosis through caspase-3 pathway in porcine preadipocytes.
abstract: Adipose tissue is an important energy reservoir, and its over-development results in obesity in humans or body fat over-deposition in livestock. Loss of preadipocytes through apoptosis has been proposed as an alternative way to reduce adipose tissue mass. At present, the effect and regulatory mechanism of Sirt1 and camptothecin on porcine preadipocyte apoptosis are still largely unknown. Here, we evaluated whether Sirt1 had any role in the basal cellular and camptothecin-induced conditions in porcine preadipocytes. Flow cytometric analysis shows that viable cells decrease as well as early apoptotic and late apoptotic cells increase after knockdown of Sirt1 in porcine preadipocytes. Camptothecin induces porcine preadipocyte apoptosis in a dose-dependent manner, assessed with the Hoechst staining and western blot analysis. Interestingly, silencing of Sirt1 significantly enhances sensitivity of porcine preadipocytes to camptothecin, which may be due to upregulation of p53, acetylated p53, Bax, cleaved caspase-3 and downregulation of Bcl-2. On the contrary, under the Sirt1 overexpression condition viable cells' number significantly increases when challenging with camptothecin, and the protein levels of cleaved caspase-3, p53, acetylated p53 and Bax are downregulated. We also find that hyperacetylated p53 is the major effect of Sirt1 knockdown by overexpression of a mutated p53, whereas Sirt1 overexpression prevents camptothecin-induced apoptosis through p53 deacetylation in preadipocytes. Furthermore, repressing preadipocyte apoptosis of Sirt1 is mediated by direct interaction with cleaved caspase-3 using immunoprecipitation and inhibition of caspase-3 transcriptional activity using luciferase reporter assays.
authors: Laboratory of Animal Fat Deposition and Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China. pwj1209@gmail.com
authors: Wei-jun
authors: WJ
authors: Pang
authors: Yan
authors: Y
authors: Xiong
authors: Yu
authors: Y
authors: Wang
authors: Qiang
authors: Q
authors: Tong
authors: Gong-she
authors: GS
authors: Yang
mesh_terms: D000107:Acetylation; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002166:Camptothecin / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism*; D004357:Drug Synergism; D005434:Flow Cytometry; D016086:Lentivirus / Q000235:genetics; D008156:Luciferases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D008156:Luciferases; D053148:Caspase 3; D056564:Sirtuin 1; D002166:Camptothecin