Positive association between expression of follicle-stimulating hormone beta and activin betaB-subunit genes in boars

Chronic ethanol perturbs testicular folate metabolism and dietary folate deficiency reduces sex hormone levels in the Yucatan micropig

Although alcoholism causes changes in hepatic folate metabolism that are aggravated by folate deficiency, male reproductive effects have never been studied. We evaluated changes in folate metabolism in the male reproductive system following chronic ethanol consumption and folate deficiency. Twenty-four juvenile micropigs received folate-sufficient (FS) or folate-depleted (FD) diets or the same diets containing 40% of energy as ethanol (FSE or FDE) for 14 wk, and the differences between the groups were determined by ANOVA. Chronic ethanol consumption (FSE and FDE compared with FS and FD groups) reduced testis and epididymis weights, testis sperm concentrations, and total sperm counts and circulating FSH levels. Folate deficiency (FD and FDE compared with FS and FSE groups) reduced circulating testosterone, estradiol and LH levels, and also testicular 17,20-lyase and aromatase activities. There was histological evidence of testicular lesions and incomplete progression of spermatogenesis in all treated groups relative to the FS control, with the FDE group being the most affected. Chronic ethanol consumption increased testis folate concentrations and decreased testis methionine synthase activity, whereas folate deficiency reduced total testis folate levels and increased methionine synthase activity. In all pigs combined, testicular methionine synthase activity was negatively associated with circulating estradiol, LH and FSH, and 17,20-lyase activity after controlling for ethanol, folate deficiency, and their interaction. Thus, while chronic ethanol consumption primarily impairs spermatogenesis, folate deficiency reduces sex hormones, and the two treatments have opposite effects on testicular folate metabolism. Furthermore, methionine synthase may influence the hormonal regulation of spermatogenesis.

Candidate gene markers for sperm quality and fertility of boar

Candidate genes gonadotropin releasing hormone receptor (GNRHR), prolactin (PRL), prolactin receptor (PRLR), follicle-stimulating hormone beta (FSHB), luteinizing hormone beta (LHB), follistatin (FST), inhibin alpha (INHA), inhibin beta A (INHBA) and inhibin beta B (INHBB) were investigated for their association with sperm quality traits of sperm concentration (SCON), motility (MOT), semen volume per ejaculate (VOL), plasma droplets rate (PDR), abnormal sperm rate (ASR) and fertility traits of non return rate (NRR) and number of piglets born alive (NBA). The experimental material included 356 boars of Pietrain (PI) and Pietrain x Hampshire (PI x HA). Analysis of variance revealed significant association of GNRHR with MOT (P = 0.0161), PDR (P = 0.0048) and ASR (P = 0.0201), INHBA was found to have significant effects on PDR (P = 0.0318) and ASR (P = 0.0067), INHBB was significant (P = 0.0360) for SCON trait. FSHB, FST, INHA, PRL, PRLR and LHB had no significant effects on any trait in this experiment.

Differential regulation of follicle stimulating hormone by activin A and TGFB1 in murine gonadotropes

BACKGROUND

Activins stimulate the synthesis of follicle stimulating hormone (FSH) in pituitary gonadotropes, at least in part, by inducing transcription of its beta subunit (Fshb). Evidence from several laboratories studying transformed murine LbetaT2 gonadotropes indicates that activins signal through Smad-dependent and/or Smad-independent pathways, similar to those used by transforming growth factor beta-1 (TGFB1) in other cell types. Therefore, given common intracellular signaling mechanisms of these two ligands, we examined whether TGFBs can also induce transcription of Fshb in LbetaT2 cells as well as in purified primary murine gonadotropes.

METHODS

Murine Fshb promoter-reporter (-1990/+1 mFshb-luc) activity was measured in LbetaT2 cells treated with activin A or TGFB1, and in cells transfected with either activin or TGFB receptors. The ability of the ligands to stimulate phosphorylation of Smads 2 and 3 in LbetaT2 cells was measured by western blot analysis, and expression of TGFB type I and II receptors was assessed by reverse transcriptase polymerase chain reaction in both LbetaT2 cells and primary gonadotropes purified from male mice of different ages. Finally, regulation of endogenous murine Fshb mRNA levels by activin A and TGFB1 in purified gonadotropes and whole pituitary cultures was measured using quantitative RT-PCR.

RESULTS

Activin A dose-dependently stimulated -1990/+1 mFshb-luc activity in LbetaT2 cells, but TGFB1 had no effect at doses up to 5 nM. Similarly, activin A, but not TGFB1, stimulated Smad 2 and 3 phosphorylation in these cells. Constitutively active forms of the activin (Acvr1b-T206D) and TGFB (TGFBR1-T204D) type I receptors strongly stimulated -1990/+1 mFshb-luc activity, showing that mechanisms down stream of Tgfbr1 seem to be intact in LbetaT2 cells. RT-PCR analysis of LbetaT2 cells and whole adult murine pituitaries indicated that both expressed Tgfbr1 mRNA, but that Tgfbr2 was not detected in LbetaT2 cells. When cells were transfected with a human TGFBR2 expression construct, TGFB1 acquired the ability to significantly stimulate -1990/+1 mFshb-luc activity. In contrast to LbetaT2 cells, primary murine gonadotropes from young mice (8-10 weeks) contained low, but detectable levels of Tgfbr2 mRNA and these levels increased in older mice (1 yr). A second surprise was the finding that treatment of purified primary gonadotropes with TGFB1 decreased murine Fshb mRNA expression by 95% whereas activin A stimulated expression by 31-fold.

CONCLUSION

These data indicate that TGFB1-insensitivity in LbetaT2 cells results from a deficiency in Tgfbr2 expression. In primary gonadotropes, however, expression of Tgfbr2 does occur, and its presence permits TGFB1 to inhibit Fshb transcription, whereas activin A stimulates it. These divergent actions of activin A and TGFB1 were unexpected and show that the two ligands may act through distinct pathways to cause opposing biological effects in primary murine gonadotropes.

Evaluation of gene expression in pigs selected for enhanced reproduction using differential display PCR: II. Anterior pituitary

The objective of this study was to identify differentially expressed genes in the anterior pituitary (AP) of sows selected for enhanced reproductive phenotypes. Selection in the Index (I) line was based on an index of ovulation rate and embryo survival, whereas random selection was used in the Control (C) line. Average numbers of fully formed piglets at birth were 12.5 +/- 1.5 and 9.9 +/- 2.0 for Line I and C sows used in this study, respectively. In order to induce luteolysis and synchronize follicle development, sows were injected (i.m.) with 2 mL of prostaglandin F2alpha analog between d 12 and 14 of the estrous cycle. Tissue was harvested 2 d (d2) or 4 d (d4) after injection, resulting in four experimental groups: Cd2 (n = 6), Cd4 (n = 4), Id2 (n = 6), and Id4 (n = 7). Differential display PCR (ddPCR) was used to search for transcriptional changes between selection lines in the AP, using samples within line but pooled across days. Northern hybridization was used to confirm ddPCR results. For ddPCR, two pools were used from each line (C and I). Three genes were confirmed to be differentially expressed between Lines I and C: G-beta like protein, ferritin heavy-chain, and follicle stimulating hormone beta subunit, whereas many other expressed sequence tags were observed to be differentially expressed but still require confirmation. Our findings indicate that long-term selection to increase ovulation rate and decrease embryo mortality has altered transcriptional patterns in the anterior pituitary, most likely as correlated responses.

Follistatin suppresses FSHbeta but increases LHbeta expression in the goldfish - evidence for an activin-mediated autocrine/paracrine system in fish pituitary

Our previous study demonstrated that recombinant goldfish activin B stimulated goldfish FSHbeta but inhibited LHbeta expression. Similar to activin B, activin A also exhibited the inverse effects on the expression of the two gonadotropins. The novel dual effects of activins on FSH and LH in the goldfish raise an interesting question as to where the activin comes from in vivo. In the present study, we first demonstrated the expression of activin, its receptors and binding protein follistatin in the goldfish pituitary, leading to a suggestion that an autocrine/paracrine regulatory system involving activin is operative in fish pituitary. To investigate the functionality of the pituitary-derived activin system in the regulation of gonadotropin biosynthesis, we further examined the effects of follistatin, an activin-binding protein, on goldfish FSHbeta and LHbeta expression. Follistatin not only reversed the effects of exogenous activin on FSHbeta and LHbeta expression but also had inverse effects on the basal expression of the genes; and its effects were opposite to those of activin. This suggests that the endogenous activin plays roles in controlling the expression of both FSHbeta and LHbeta genes. It is conceivable that any factors that influence the intrapituitary activin system in vivo will likely affect the biosynthesis of the two gonadotropins in the goldfish.

Molecular cloning of the porcine inhibin-betaB gene and reassignment to chromosome 15

Inhibins are gonadal glycoproteins belonging to the transforming growth factor-beta superfamily that act to suppress pituitary follicle stimulating hormone and are composed of a common alpha-subunit linked by disulphide bonds to either a betaA- or betaB-subunit. The porcine inhibin-alpha, -betaA (INHBA) and -betaB (INHBB) subunit genes have previously been mapped to chromosomes 15, 18 and 12, respectively. Over 6.7 kb of the INHBB gene was sequenced from a porcine genomic cosmid clone and found to contain two microsatellites, one in intron 1 and the other in the 3'-untranslated region. Both microsatellites mapped to pig chromosome 15 at relative position 48 cm. This sequence was greater than 99% identical to two previously reported partial non-contiguous cDNAs for porcine INHBB. Non-coding regions also had a high degree (79-88%) of identity with the corresponding regions of the human gene. Based on sequence information and mapping of two novel microsatellite markers, we reassigned porcine INHBB to chromosome 15, which is consistent with comparative physical and linkage maps of this chromosome and human chromosome 2.

Identification and characterization of a new allele for the beta subunit of follicle-stimulating hormone in Chinese pig breeds

During evaluation of follicle-stimulating hormone-beta (FSHB) expression in anterior pituitary glands by an RNase protection assay (RPA), the expected fragment of 205 nucleotides at positions 759-963 was not detected in one boar that had moderate plasma and pituitary FSH concentrations. After subcloning and sequencing, mRNA from this boar lacked an 11-bp fragment (5'-CATTTGGAAAC-3') at nucleotide positions 807-817 of the 3'-untranslated region (3'-UTR, D allele). Wild-type FSHB (WT allele) was present in pituitary RNA and genomic DNA in both Meishan (MS) and White Composite (WC) pigs; whereas the D allele was present only in MS pigs (P < 0.01; 5/6 MS vs. 0/6 WC). Also, we found the D allele in five other Chinese breeds but absent in ten American Landrace, 11 Yorkshire and 17 Berkshire pigs. Additionally, the D allele had one silent nucleotide change in the coding region plus six, single nucleotide changes in the 3'-UTR.