Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Follistatin, a glycosylated single chain protein that was originally isolated from ovarian follicular fluid, can specifically inhibit the biosynthesis and secretion of FSH by the pituitary. Follistatin has also been isolated from bovine pituitary and shown to have activin-binding activity. We wished to determine whether the follistatin gene is expressed in the rat pituitary and, if so, to identify the specific cell types. A 337-basepair fragment of the follistatin cDNA was amplified by polymerase chain reaction from a rat ovarian cDNA library and subcloned into pGEM3. Low levels of follistatin mRNA from rat pituitary poly(A)+RNA were detected by ribonuclease protection analysis using a specific follistatin riboprobe generated from the cDNA clone. The presence of follistatin mRNA in the pituitary was confirmed using polymerase chain reaction to amplify the follistatin cDNA generated by reverse transcription from total rat pituitary RNA. Furthermore, in situ hybridization studies combined with immunostaining for pituitary hormones were used to localize follistatin mRNA within the rat pituitary. When a biotinylated oligonucleotide complementary to follistatin mRNA was used with dispersed pituitary cells from rats in diestrus II, labeling was found in 5-7% of the cells. The in situ hybridization protocol was then combined with immunolabeling protocols for LH beta, FSH beta, or S-100 protein (a marker for folliculostellate cells). Follistatin mRNA was detected in 70 +/- 5% of LH beta cells, 44 +/- 11% of FSH beta cells, and 35 +/- 2% of folliculostellate cells. These results suggest that follistatin is expressed in pituitary gonadotropes and folliculostellate cells during diestrus II, where it may have a role in the local autocrine or paracrine regulation of FSH biosynthesis and secretion, possibly by binding to and modulating the effects of activin in the pituitary.
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PMID:Follistatin gene expression in the pituitary: localization in gonadotropes and folliculostellate cells in diestrous rats. 157 12

Follistatin was originally identified as a specific inhibitor of follicle stimulating hormone secretion and later characterized as a binding protein for activin. Since activin regulates hormone secretion and cell differentiation, the importance of understanding the mechanisms regulating the synthesis of its binding protein, follistatin, is evident. To study the regulation of follistatin gene expression, we first determined the transcription start site (cap site) of the rat follistatin gene using primer extension and ribonuclease protection assay. Our results led to the identification of multiple cap sites located at three different positions of the promoter. DNA sequence analysis revealed that each cap site was located at approximately 30 nucleotide (nt) downstream of three distinct TATA-like sequences. In primary cultures of rat granulosa cells, transfection studies using 5'-flanking regions of follistatin gene fused to the chloramphenicol acetyltransferase (CAT) reporter gene revealed the presence of two DNA segments that act to suppress basal transcriptional activity. The promoter activity of the CAT construct containing 2.6 kilo base pairs (kb) of 5'-flanking region was induced 2.5-fold above basal activity by forskolin (10 microM), and 1.6-fold by 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 nM). Co-treatment with forskolin and TPA resulted in a 6.4-fold induction in its promoter activity, suggesting that two distinct signal transduction pathways, the cAMP-dependent protein kinase-A pathway and diacylglycerol-dependent protein kinase-C pathway, act coordinately to modulate follistatin gene transcription. Experiments using a series of 5'-flanking region deletion constructs located the regulatory regions responsive to these two pharmacological agents at nt -312 to -32 and -35 to +139.
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PMID:Structural and functional characterization of the rat follistatin (activin-binding protein) gene promoter. 847 73

In rats, FSHbeta gene expression and FSH secretion are increased and decreased, respectively, by pituitary activin and follistatin. Because little information is available on the paracrine control of FSH secretion in the primate, follistatin and activin/inhibin beta(B) messenger RNA (mRNA) levels were measured in pituitaries of adult male rhesus monkeys 6 weeks after castration or sham surgery (n = 5/group). Follistatin mRNA was determined by quantitative RT-PCR assay using oligonucleotide primers designed to span exons 3-5 of the human follistatin gene. Activin/inhibin beta(B) mRNA levels were measured by ribonuclease protection. Orchidectomy resulted in a 100-fold increase in plasma FSH concentrations and a 60-fold rise in those of LH. In castrated monkeys, levels of mRNA encoding FSHbeta, LHbeta, alpha- subunit, and GnRH receptor (GnRH-R) were increased 21-, 2.1-, 1.7-, and 1.7-fold, respectively (P < 0.01). Levels of pituitary follistatin and activin/inhibin beta(B) mRNAs, however, were similar in castrated and intact animals. These data suggest that the paracrine control of FSH secretion in the male differs substantially in primates and rodents. Specifically, the relatively greater postcastration rise in FSHbeta gene expression and FSH secretion in the adult male monkey may result because in this species pituitary follistatin gene expression does not increase after orchidectomy, as it does in the rat.
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PMID:Pituitary follistatin and activin gene expression, and the testicular regulation of FSH in the adult Rhesus monkey (Macaca mulatta). 1141 6