Poly(ADP-ribosyl)ation is involved in pro-survival autophagy in porcine blastocysts

SUMMARY Poly(ADP‐ribosyl)ation (PARylation) prevents apoptosis through its involvement in pro‐survival autophagy in cultured cells; whether or not the same is true for pre‐implantation embryos has not yet been documented. In this study, we investigated the participation of PARylation and autophagy in in vitro porcine pre‐implantation embryo development. The transcript levels of autophagy‐related genes and poly(ADP‐ribose) polymerase 1 (PARP1), an enzyme required for PARylation, were transiently up‐regulated by fertilization, decreased at the late 1‐cell stage, and maintained until the blastocyst stage. LC3, a marker of autophagosomes, and poly(ADP‐ribose) (PAR) polymer were present in all stages of pre‐implantation development. Exposure of embryos to 3‐methyladenine, an autophagy inhibitor, or 3‐aminobenzamide, a PARP inhibitor, suppressed the development of blastocysts. Pharmacological inhibition of PARylation further suppressed pro‐survival autophagy by decreasing the expression of autophagy‐related genes (ATG5, BECLIN1, and LC3) and decreasing LC3 protein abundance while increasing the rate of apoptosis in blastocysts. Deficiency in autophagy also induced abnormal accumulation of SQSTM1/p62 aggregates in porcine blastocysts. Collectively, these data suggest that PARylation is involved in selective autophagic degradation of ubiquitinated proteins, functioning in a pro‐survival role, in porcine in vitro‐produced embryos. These pro‐survival regulatory mechanisms may be important for the control of embryo quality. Mol. Reprod. Dev. 83: 37–49, 2016. © 2015 Wiley Periodicals, Inc.