Dexamethasone-induced Intra-Uterine Growth Restriction impacts NOSTRIN and its downstream effector genes in the rat mesometrial uterus

Intra-Uterine Growth Restriction (IUGR) is a major cause of fetal and neonatal mortality. Understanding the impact of IUGR on utero-placental gene expression is key to developing effective therapy. In this report we elucidated the impact of IUGR on NOSTRIN and its downstream effector gene expression in the utero-placental compartments. We showed here that induction of IUGR by maternal dexamethasone administration in rats led to up-regulation of NOSTRIN transcript and protein in the mesometrial triangle of the uterus (MG) and not in other utero-placental compartments as compared to control. This was associated with down-regulation of twelve genes and four cytokines that were known to be regulated by NOSTRIN and also required for maintenance of pregnancy. Interestingly, there was remarkable decrease in phosphorylation of RelA transcription factor in the MG during IUGR in line with the fact that the down regulated genes harbour RelA transcription activation domain in their promoters. Furthermore, HIF-1α level was reciprocal to NOSTRIN expression pattern in the mesometrial compartment during IUGR and also in CoCl(2) treated endothelial cells. Over-expression of HIF-1α led to a decrease in NOSTRIN levels suggesting inhibition of Nostrin transcription by HIF-1α. Our findings highlight the importance of NOSTRIN in uterine pathophysiology during IUGR.