Anti-Fshb polyclonal antibody

The high mobility group factor NUPR1, also known as p8 and com1, plays a role in temporal expression of the beta subunit of luteinizing hormone, LHB, during gonadotroph development. At Embryonic Day (e) 16.5, LHB is detectable in wild-type (Nupr1(+/+)) but not Nupr1 knockout (Nupr1(-/-)) mice. LHB is initiated by e17.5 in Nupr1(-/-) mice, and expression is fully recovered by Postnatal Day (p) 2. Factors indicative of pituitary maturation, GATA2, CGA, and TSH, are not differentially expressed in Nupr1(-/-) and Nupr1(-/-) embryos at e17.5. Therefore, the delay in LHB expression does not appear to result from delayed pituitary development. in addition, the role of NUPR1 in gonadotropin expression appears specific for LHB, as no difference in FSHB is observed in Nupr1(-/-) and Nupr1(+/+) embryos. The gonads are also impacted by the absence of NUPR1. Ovaries of female Nupr1(-/-) mice lack corpora lutea (CL) at 8 wk, an age at which CL are present in all Nupr1(+/+) littermates. Sexual maturity is recovered by 11 wk in Nupr1(-/-) mice. Conversely, the testes of Nupr1(-/-) males appear normal through 8 mo of age. By 10 mo, however, these mice develop a condition in which a significant number of seminiferous tubules lack germ cells, an abnormality reminiscent of human Sertoli-cell-only syndrome. NUPR1 is undetectable in Nupr1(+/+) gonadotrophs by p2 and remains absent in adulthood, but quantitative PCR analysis indicates Nupr1(+/+) adult ovaries and testes express Nupr1 mRNA. Therefore, the ovarian and testicular phenotypes may be due to the loss of NUPR1 directly at the gonads.

Pulsatile GnRH (GNRH) differentially regulates LH and FSH subunit genes, with faster frequencies favoring Lhb transcription and slower favoring Fshb. Various intracellular pathways mediate the effects of GNRH, including CaMK II (CAMK2), ERK, and INK. We examined whether activation of these pathways is regulated by GNRH pulse frequency in vivo. GNRH-deficient rats received GNRH pulses (25 ng i.v. every 30 or 240 min for 8 h, vehicle to controls). Pituitaries were collected 5 min after the last pulse, bisected, and one half processed for RNA (to measure beta subunit primary transcripts [PTs]) and the other for protein. Phosphorylated CAMK2 (phospho-CAMK2), ERK (mitogen-activated protein kinase 1/3 [MAPK1/3], also known as p42 ERK2 and p44 ERK1, respectively), and JNK (MAPK8/9, also known as p46 JNK1 and p54 JNK2, respectively) were determined by Western blotting. The 30-min pulses maximally stimulated Lhb PT (8-fold), whereas 240 min was optimal for Fshb PT (3-fold increase). Both GNRH pulse frequencies increased phospho-CAMK2 4-fold. Activation of MAPK1/3 was stimulated by both 30- and 240-min pulses, but phosphorylation of MAPK3 was significantly greater following slower GNRH pulses (240 min: 4-fold, 30 min: 2-fold). MAPK8/9 activation was unchanged by pulsatile GNRH in this paradigm, but as previous results showed that GNRH-induced activation of MAPK8/9 is delayed, 5 min after GNRH may not be optimal to observe MAPK8/9 activation. These data show that CAMK2 is activated by GNRH, but not in a frequency-dependant manner, whereas MAPK3 is maximally stimulated by slow-frequency GNRH pulses. Thus, the ERK response to slow pulse frequency is part of the mechanisms mediating Fhb transcriptional responses to GNRH.