title: SIRT1-mediated FoxOs pathways protect against apoptosis by promoting autophagy in osteoblast-like MC3T3-E1 cells exposed to sodium fluoride.
abstract: Fluorine may result in damage to teeth, bones and other body tissues, and is a serious public health problem. SIRT1 deacetylates FOXOs, which brings about apoptosis and autophagy promotion or suppression. Fluorine may induce cell apoptosis, however, the role of autophagy in apoptosis induced by fluorine is still poorly understood, and the interaction between SIRT1 and FOXOs should be further illustrated. Therefore, this study investigated the mechanisms underlying the NaF- induced apoptosis and autophagy in osteoblast-like MC3T3-E1 cells in vitro through activating or inhibiting SIRT1. Via RT-PCR, western blot, flow cytometry assays, fluorescence and laser confocal microscopy, it was found that NaF induced both cell apoptosis and autophagy. Results also showed that NaF up-regulated SIRT1 expression in a dose-dependent manner. The autophagy of MC3T3-E1 was also up- regulated indirectly whilst apoptosis was significantly attenuated when incubated with the SIRT1 activator SRT1720. When SIRT1 inhibitor Ex-527 was used, the latter effects were reversed. Furthermore, SIRT1 increased deacetylation of FoxO1 and promoted the up-regulation of its target substrate Rab7, as well as increase of Bnip3 which was substrate of FoxO3, and we hypothesize that these pathways may cause an increase in autophagic flux and a reduction in apoptosis. In conclusion, SIRT1-induced autophagy enhancement protects against fluoride-induced apoptosis through autophagy induction in MC3T3-E1 cells, which may be associated with a SIRT1-FoxO1-Rab7 axis and a SIRT1-FoxO3-Binp3 axis. The role of SIRT1 in selecting between cell survival and death provides a potential therapeutic strategy in fluorosis.
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Xiaolong
authors: X
authors: Gu
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Dandan
authors: D
authors: Han
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Wei
authors: W
authors: Chen
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Limei
authors: L
authors: Zhang
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Qianyun
authors: Q
authors: Lin
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Jian
authors: J
authors: Gao
authors: UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors: Séamus
authors: S
authors: Fanning
authors: College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, P R China.
authors: Bo
authors: B
authors: Han
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D002460:Cell Line; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D056564:Sirtuin 1 / Q000378:metabolism*; D012969:Sodium Fluoride / Q000633:toxicity*
chemical_list: D051858:Forkhead Transcription Factors; D012969:Sodium Fluoride; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1
keywords: MC3T3-E1 cells; SIRT1; apoptosis; autophagy; sodium fluoride