Organosulfur compounds induce cytoprotective autop...

Organosulfur compounds induce cytoprotective autophagy against apoptosis by inhibiting mTOR phosphorylation activity in macrophages

Yanyang Wu1 　Yongquan Hu2，3，4 　Haiyan Zhou2，3，4 　Jiayu Zhu2，3，4 　Zhongyi Tong5 　Si Qin1，* 　and Dongbo Liu2，3，4，*

1.College of Food Science and Technology，Hunan Agricultural University，Changsha 410128，China；

2.Horticulture and Landscape College，Hunan Agricultural University，Changsha 410128，China；

3.Hunan Co-Innovation Center for Utilization of Botanical Functional Ingredients，Changsha 410128，China；(https://www.daowen.com)

4.State Key Laboratory of Subhealth Intervention Technology，Changsha 410128，China，and 5 Department of Pathology，the Second Xiangya Hospital of Central South University，Changsha，410011，China

Abstract：Organosulfur compounds(OSCs)are the bioactive components of garlic.Some OSCs have apoptotic or autophagy-inducing effects.Autophagy plays roles in both cytoprotection and apoptosis-related cell death，and the interaction between autophagy and apoptosis is important in the modulation of immune responses.The mechanism of an OSC-mediated effect via the interaction of autophagy and apoptosis is unknown.In this study，the effects of five OSC compounds on autophagy in the macrophage cell line RAW264.7 and primary macrophages were investigated.We found that S-allylcysteine(SAC)，diallyl disulde(DADS)and diallyl tetrasulfide(DTS)treatment increased the number of autophagosomes of RAW264.7 cells，inhibited the phosphorylation of ribosomal protein S6 kinase beta-1(p70S6K/S6K1)which is a substrate of mammalian target of rapamycin(mTOR)，and significantly enhanced autophagy flux.The induction of autophagy by SAC，DADS and DTS was inhibited by stably knocking down the expression of autophagy-related gene 5(ATG5)with short hairpin RNA(shRNA).Further experiments confirmed that SAC，DADS and DTS also induced apoptosis in RAW264.7 cells.The induction of apoptosis and Caspase 3 activity by SAC，DADS and DTS were increased by stably knocking down of ATG5 expression with shRNA in RAW264.7 cells or treating with 5 mM 3-MA in primary macrophages.Our results suggest that SAC，DADS and DTS induce both autophagy and apoptosis.The autophagy induction protects macrophages from apoptosis by inhibiting mTOR phosphorylation activity to maintain the mass of immune cells.

Keywords：autophagy，macrophage，organosulfur compounds，apoptosis，mTOR