Abstract:
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 Ca 2+ 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.
激活转录因子 6 (activating transcription factor 6,ATF6) 是内质网中的三种传感器蛋白之一,是内质网应激诱导细胞凋亡的重要调节因子。 ATF6位于内质网中并在激活后转移到高尔基体,在那里它被 site-1-蛋白酶 (S1P) 切割以生成氨基末端胞质片段。 尽管最近的研究已在ATF6的调控机制方面取得了进展,但ATF6在高温(high temperature,HT) 情况下,对猪早期胚胎发育过程的影响还不清楚。在该研究中,胚胎被分为四组:对照组、HT组、HT+ATF6-KD组和 HT+PF(S1P抑制剂)组。结果表明,HT暴露诱导胚胎内质网应激,从而增加 ATF6 蛋白表达并导致囊胚率降低。由于显微注射ATF6 dsRNA,ATF6的表达水平在HT胚胎中被敲低,结果显示,ATF6-KD可以减弱由HT所导致的CHOP(内质网应激标记物)的表达增加以及Ca 2+的释放。 此外,ATF6-KD还减轻了HT诱导的ER应激所引起的细胞器稳态失衡,数据还显示ATF6-KD减少了HT胚胎中的高尔基体和线粒体功能障碍。AIFM2作为ATF6的重要下游蛋白,ATF6-KD减少了AIFM2介导的HT胚胎凋亡的发生。总之,这些结果表明 ATF6 是早期猪胚胎发育过程中,由 HT诱导的内质网应激和细胞器稳态失衡所引起细胞凋亡的重要介质。.