ATF6 aggravates apoptosis in early porcine embryonic development by regulating organelle homeostasis under high-temperature conditions

摘要

Activating transcription factor 6(ATF6),one of the three sensor proteins in the endoplasmic reticulum(ER),is an important regulator of ER stress-induced apoptosis.ATF6 resides in the ER and,upon activation,is translocated to the Golgi apparatus,where it is cleaved by site-1 protease(S1P)to generate an amino-terminal cytoplasmic fragment.Although recent studies have made progress in elucidating the regulatory mechanisms of ATF6,its function during early porcine embryonic development under high-temperature(HT)stress remains unclear.In this study,zygotes were divided into four groups:control,HT,HT+ATF6 knockdown,and HT+PF(S1P inhibitor).Results showed that HT exposure induced ER stress,which increased ATF6 protein expression and led to a decrease in the blastocyst rate.Next,ATF6 expression was knocked down in HT embryos under microinjection of ATF6 double-stranded RNA(dsRNA).Results revealed that ATF6 knockdown(ATF6-KD)attenuated the increased expression of CHOP,an ER stress marker,and Ca2+release induced by HT.In addition,ATF6-KD alleviated homeostasis dysregulation among organelles caused by HT-induced ER stress,and further reduced Golgi apparatus and mitochondrial dysfunction in HT embryos.AIFM2 is an important downstream effector of ATF6.Results showed that ATF6-KD reduced the occurrence of AIFM2-mediated embryonic apoptosis at HT.Taken together,our findings suggest that ATF6 is a crucial mediator of apoptosis during early porcine embryonic development,resulting from HT-induced ER stress and disruption of organelle homeostasis.