Augmentation of and Suppression of Expression in the Pituitary Gland of Female Annexin A5 Null Mouse.

GnRH enhances the expression of annexin A5 (ANXA5) in pituitary gonadotropes, and ANXA5 enhances gonadotropin secretion. However, the impact of ANXA5 regulation on the expression of pituitary hormone genes remains unclear. Here, using quantitative PCR, we demonstrated that ANXA5 deficiency in female mice reduced the expression of and in their pituitary glands. Transcriptome analysis confirmed a specific increase in mRNA expression in addition to lower levels of expression in ANXA5-deficient female pituitary glands. This gene was then found to be a GnRH-inducible immediate early gene, and its increased expression caused protein to accumulate in the nucleus after administration of a GnRH agonist in LβT2 cells, which are an in vitro pituitary gonadotrope model. The increase in ANXA5 protein levels in LβT2 cells clearly suppressed expression. siRNA-mediated inhibition of expression increased expression. The results revealed that GnRH stimulates and sequentially. NR4A3 suppression of may be necessary for later massive secretion of FSH by GnRH in gonadotropes, and would be negatively regulated by ANXA5 to increase FSH secretion.