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

Abstract

Gonadotropin-releasing hormone (GnRH) stimulation of annexin A1 (ANXA1) and A5 (ANXA5) mRNA expression was analyzed in LβT2 gonadotrope cells. Quantitative polymerase chain reaction results showed that a GnRH analog (GnRHa) stimulated the expression of both ANXA1 and A5 mRNA with a peak at 12 h of incubation; however, ANXA1 mRNA was extremely stimulated (60 folds). Immunocytochemical analysis confirmed these findings. A GnRH antagonist inhibited the effect of GnRHa. ANXA1 and A5 mRNA levels were significantly increased by protein kinase C (PKC) activator (12-O-Tetradecanoylphorbol-13-acetate; TPA), but not by dibutyryl cAMP. GnRHa-stimulated induction of ANXA1 and A5 mRNA was inhibited by PKC (GF109203) and MEK inhibitors (PD98059). TPA increased ANXA1 and A5 mRNA expression in a dose-dependent manner (1 nM to 10 μM), while the extent of the increase was much greater in ANXA1. After stimulation with 10 nM or 1 μM TPA, ANXA1 and A5 mRNA levels were increased at 6 h. ANXA1 mRNA levels were higher in the 1 μM TPA than in the 10 nM TPA treatment, whereas 1 μM TPA did not show further stimulation of ANXA5 mRNA compared to 10 nM TPA. These results clearly show that ANXA1 mRNA expression is stimulated by GnRH through PKC like ANXA5, and the response of ANXA1 is much larger than that of ANXA5. A close relationship between these annexins and a significant role for ANXA1 in GnRH action at gonadotropes is suggested.

Changes in the expressions of annexin A1, annexin A5, inhibin/activin subunits, and vitamin D receptor mRNAs in pituitary glands of female rats during the estrous cycle: correlation analyses among these factors

“…Furthermore, ANXA1 is present in abundance in the folliculo-stellate cells of the rat pituitary [ 50 ], and the action of 17β-estradiol in the regulation of ANXA1 might be mediated by corticosterone [ 10 ]. Additionally, Anxa1 expression was strongly stimulated by a GnRH analog in LβT2 cells [ 15 , 36 ] and was stimulated by 17β-estradiol in the folliculo-stellate-like cell line, TtT/GF [ 10 ]. Hence, further studies need to investigate the regulation of ANXA1 and the involvement of estrogen with respect to its direct action on gonadotropes in vivo .…”

“…Their estrous cycles were monitored using daily vaginal smears. As genes examined herein included GnRH-inducible genes, such as Anxa1 and Anxa5 [ 36 ], samples were collected in the morning (1000–1200 hr) to minimize the effect of GnRH surge. The rats were euthanized by decapitation between 1000 and 1200 hr on metestrus (D1), diestrus (D2, the day following metestrus), proestrus (P), and estrus (E).…”

“…Real-time PCR analyses of the cDNA samples were performed using SYBR Green Master Mix (Applied Biosystems, Foster City, CA, USA) on QuantStudio software (Applied Biosystems). The primers for the genes encoding ANXA1, ANXA5, VDR, inhibin/activin βB-subunit (ACTβB), inhibin α-subunit (INHα), FST, luteinizing hormone (LH) β subunit (LHβ), FSHβ subunit (FSHβ), GnRH receptor (GnRH-R), and ribosomal protein L19 (RPL19) [ 15 , 36 ] were used for each PCR assay. The primer sequences are listed in Table 1…”

“…Reportedly, ANXA1 and ANXA5 are produced in the pituitary gland [ 15 , 24 , 25 , 27 , 50 ]. In fact, we have previously demonstrated that a GnRH agonist (GnRHa) can stimulate Anxa1 and Anxa5 expressions via the GnRH receptor (GnRH-R)-mitogen-activated protein kinase (MAPK) cascade in the mouse gonadotrope-derived cell line, LβT2 [ 36 ].…”

Gonadotropin-releasing hormone stimulation of annexin A5 expression in the thymus of male rats

“…We previously found that the annexin family proteins annexin A5 and A1 (ANXA5 and ANXA1) are expressed in pituitary gonadotropes, and their expression could be augmented by GnRH in rats [ 8 , 10 , 13 ]. Furthermore, ANXA5 augments gonadotropin secretion by enhancing the stimulatory action of GnRH on gonadotropin secretion [ 10 ].…”