Annexin A1 is a novel target gene of gonadotropin-releasing hormone in LβT2 gonadotrope cells

Abstract

Gonadotropin-releasing hormone (GnRH) regulates gonadotropin secretion. We previously demonstrated that the expression of annexin A5 (ANXA5) is stimulated by GnRH in gonadotropes and has a significant role in gonadotropin secretion. It is therefore of interest to know whether other members of the ANXA family, which consists of twelve structurally related members, are also regulated by GnRH. Therefore, the expression of all annexins was examined in LβT2 gonadotrope cells. ANXA4, A5, A6, A7 and A11 were detected in LβT2 cells. The expression of ANXA5 and A1 mRNA was stimulated by a GnRH agonist. An increase in ANXA1 protein by this agonist was demonstrated by western blotting. Immunohistochemistry showed that ANXA1 was present in the nucleus and to a lesser extent in the cytoplasm of some rat pituitary cells. The GnRH agonist induced translocation of ANXA1 to the periphery of LβT2 cells. The presence of ANXA1 in gonadotropes and its increase upon GnRH agonist treatment were confirmed in a primary pituitary cell culture. ANXA1 expression was also demonstrated in the ovary, the testis, the thyroid gland and the pancreas in a different manner to that of ANXA5. These data suggest that ANXA1 is a novel GnRH target gene in gonadotropes. ANXA1 also may be a target of local GnRH in peripheral tissues and may have a different role than that of ANXA5.

The expression of Annexin A1 and A5 mRNA by gonadotropin-releasing hormone in LβT2 gonadotrope cells

“…The distribution of ANXA1 in LβT2 cells was similar to that observed in a previous report [16], even though the GnRHa concentration and incubation times were different. ANXA1 and A5 are both GnRH-inducible genes, but the response to GnRH is extremely high for ANXA1.…”

“…We have demonstrated that ANXA5 at least partly regulate GnRH-stimulated gonadotropin secretion in pituitary gonadotropes [12][13][14][15]. Recently, we found that GnRH significantly increased the expression of ANXA1 in LβT2 cells [16]. In addition, a preliminary experiment showed that ANXA1 promotes LH secretion in LβT2 cells [17].…”

“…Recently, we detected ANXA4, A5, A6, A7, and A11 mRNAs in LβT2 cells and showed that a GnRH agonist (GnRHa) increased mRNA levels of only ANXA1 and A5 among all annexins in LβT2 cells [16]. GnRHa dramatically increased ANXA1 mRNA levels at trace amounts, without GnRH [16]. ANXA1 promotes LH secretion in LβT2 cells [17].…”

“…Real-time PCR was performed using SYBR Green Master Mix (Applied Biosystems, Foster City, CA, USA) and QuantStudio (Applied Biosystems). Previously described primers (ANXA1, 5'-ATGTTGCTGCCTTGC ACAAA-3' and 5'-CCAAGGGCTTTCCATTCTCCT-3'; ANXA5, 5'-CTCTGTTTGGCAGGGACCTT-3' and 5'-G GCATCGTAGAGTCGTGAGG-3'; and RPL19, 5'-CTG ATCAAGGATGGGCTGAT-3' and 5'-TTCAGCTTGTG GATGTGCTC-3') were used for each PCR assay [16]. ANXA1 and A5 mRNA levels were standardized by dividing by the RPL19 mRNA level in the same sample.…”

Augmentation of Nr4a3 and Suppression of Fshb Expression in the Pituitary Gland of Female Annexin A5 Null Mouse

“…This is probably because of the presence of a redundant mechanism of the other annexin family members, ANXA1 through 13, 12 does not exist. Recently, we demonstrated that the expression of ANXA1 is also facilitated by GnRH [ 40 ]. Further analysis of ANXA5 function as it relates to gonadotropin secretion is needed.…”