RACK1 may participate in placental development via regulating proliferation and migration of trophoblast cell in pigs following intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a severe complication in swine production. Placental insufficiency is responsible for inadequate fetal growth, but the specific etiology of placental dysfunction-induced IUGR in pigs remains poorly understood. In this work, placenta samples supplying the lightest-weight (LW) and mean-weight (MW) pig fetuses in the litter at day 65 (D65) of gestation were collected, and the relationship between fetal growth and placental morphologies and functions was investigated using histomorphological analysis, RNA sequencing, quantitative polymerase chain reaction, and in-vitro experiment in LW and MW placentas. Results showed that the folded structure of the epithelial bilayer of LW placentas followed a poor and incomplete development compared with that of MW placentas. A total of 632 differentially expressed genes (DEGs) were screened out between the LW and MW placentas, and RACK1 was found to be downregulated in LW placentas. The DEGs were mainly enriched in translation, ribosome, protein synthesis, and mTOR signaling pathway according to GO and KEGG enrichment analyses. In-vitro experiments indicated that the decreased RACK1 in LW placentas may be involved in abnormal development of placental folds (PFs) by inhibiting the proliferation and migration of porcine trophoblast cells. Taken together, these results revealed that RACK1 may be a vital regulator in the development of PFs via regulating trophoblast ribosome function, proliferation, and migration in pigs.