title: Heat stress inhibits proliferation, promotes growth, and induces apoptosis in cultured Lantang swine skeletal muscle satellite cells.
abstract: Proliferation suppression and apoptosis are the prominent characteristics induced by heat stress (HS) in cells, whereas the effects of HS on cell growth (mass accumulation) are unknown. In this study, Lantang swine (an indigenous breed of China) skeletal muscle satellite cells (SCs) were pre-cultured at 37 °C for 24 h. The HS group was subjected to HS at 41 °C, while the control group was maintained at 37 °C. Heat shock protein 70 (HSP70) expression and SC size are significantly increased (P<0.05) by HS, but cell proliferation is suppressed (P<0.05) and apoptosis is induced (P<0.05). HS led to a lower percentage of SCs in the G0/G1 phase (P<0.05) together with a higher percentage of SCs in the S phase (P<0.05). However, the percentage of SCs in the G2/M phase was decreased (P<0.05) at 48 h but then increased (P<0.05) at 72 h with HS. In addition, the phosphorylation ratios of protein kinase b (Akt), ribosomal protein S6 kinase (S6K), and ribosomal protein S6 were increased (P<0.05) by HS. Nevertheless, the phosphorylation ratios of the 4E binding protein 1 and the eukaryotic initiation factor-4E were indistinguishable (P>0.05) from those of the control group. The phosphorylation ratio of the mammalian target of rapamycin (mTOR) (Ser(2448)) increased (P<0.05) within 48 h, and apparent differences were abrogated at 72 h (P>0.05). Moreover, cleaved caspase-3 expression was increased at 72 h (P<0.05). These findings indicate that HS induces apoptosis and disrupts cell cycle distribution to decrease the number of cells. Additionally, HS can promote SC growth via an activated Akt/mTOR/S6K signaling pathway.
authors.affiliation: College of Animal Science, South China Agricultural University / National Engineering Research Center for Breeding Swine Industry / Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, Guangzhou 510642, China; Davis Heart & Lung Research Institute, Wexner Medical Center at the Ohio State University, Columbus, OH 43210, USA.
authors.forename: Chun-qi
authors.initials: CQ
authors.lastname: Gao
authors.forename: Yin-ling
authors.initials: YL
authors.lastname: Zhao
authors.forename: Hai-chang
authors.initials: HC
authors.lastname: Li
authors.forename: Wei-guo
authors.initials: WG
authors.lastname: Sui
authors.forename: Hui-chao
authors.initials: HC
authors.lastname: Yan
authors.forename: Xiu-qi
authors.initials: XQ
authors.lastname: Wang
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D059447:Cell Cycle Checkpoints / Q000502:physiology*; D049108:Cell Enlargement; D049109:Cell Proliferation / Q000502:physiology*; D002478:Cells, Cultured; D018869:Heat-Shock Response / Q000502:physiology*; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology* / Q000502:physiology*; D013552:Swine
keywords: Akt/mTOR/S6K pathway; Apoptosis; Cell growth; Cell proliferation; Heat stress; Swine