Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thioredoxin-like activity of human follicle stimulating hormone (hFSH), hFSH-beta-(83-88) peptide amide (hFSH-beta-(83-88) which has a sequence similar to the thioredoxin active center (-His-Cys-Gly-Lys-Cys-Asp-)) and thioredoxin-(31-36)-peptide amide (TD-(31-36) which contains the redox-active dithiol of thioredoxin (-Trp-Cys-Gly-Pro-Cys-Lys-)) was characterized by their ability to reactivate reduced and denatured bovine pancreatic ribonuclease (RNase). This assay reflects the recently recognized ability of thioredoxin to catalyze disulfide bond formation in proteins. Compared to uncatalyzed refolding of reduced, denatured substrate, hFSH was approximately 10-fold more active than thioredoxin on a molar basis. The catalytic activity of hFSH-beta-(83-88) and TD-(31-36) was equivalent to that of an equimolar concentration of thioredoxin. Screening of 11 overlapping peptide amides representing the entire primary structure of hFSH-beta-subunit indicated that hFSH-beta-(81-95), which contains the sequence similar to the thioredoxin active center within a receptor-binding region of the hFSH-beta-subunit, possesses strong thioredoxin-like activity and was more active than an equimolar concentration of thioredoxin. In contrast, hFSH-beta-(33-53), a thiol-containing peptide which corresponds to a second FSH receptor-binding domain but lacks the sequence similar to the thioredoxin active center, was inactive. Synthetic peptide amides corresponding to other regions of hFSH-beta-subunit were less effective than hFSH-beta-(81-95) in reactivating reduced and denatured RNase. Our data provide evidence that the recently reported thioredoxin-like catalytic activity of FSH may be due, at least in part, to the redox-active dithiol present within a receptor-binding domain of its beta-subunit, and thus may have a physiological role in receptor binding or signal transduction.
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PMID:A synthetic peptide corresponding to hFSH-beta-(81-95) has thioredoxin-like activity. 177 2

Androgens are known to exert a variety of effects on an organism while follicle-stimulating hormone (FSH) seems to act specifically on the gonads. To investigate whether these effects are reflected by the expression pattern of the androgen receptor (AR) or the FSH receptor (FSHR) we screened 38 different tissues and organs of one intact and one castrated male non-human primate (Macaca fascicularis). By means of a highly sensitive ribonuclease protection assay (RPA) we demonstrated AR mRNA expression in all tissues of the intact monkey investigated. Immunohistochemistry of selected organs from this monkey revealed a good correlation between AR mRNA and protein expression. In the castrated monkey, the overall AR mRNA expression was markedly lower compared with the intact monkey, although higher expression was present in the pituitary, thyroid and prostate glands. FSHR mRNA was only detected in testicular tissue. This study has revealed, for the first time, ubiquitious expression of the AR mRNA in a non-human primate. The testis-specific expression of the FSHR highlights the importance of FSH for spermatogenesis with the testis being apparently the only target organ.
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PMID:Ubiquitous expression of the androgen receptor and testis-specific expression of the FSH receptor in the cynomolgus monkey (Macaca fascicularis) revealed by a ribonuclease protection assay. 757 19

Sertoli cell lines have been established from H-2K(b)-tsA58 transgenic mice carrying an inducible temperature-sensitive SV40 T antigen in their germline. All cell lines tested for expression of Sertoli cell products by reverse transcription-polymerase chain reaction were shown to express mRNAs for alpha-inhibin, Steel factor, SGP-2, and transferrin as well as for androgen receptor and the orphan nuclear receptor SF-1. Selected cell lines were shown by immunocytochemistry to express the established Sertoli cell-specific pattern of cytoskeletal markers. The FSH receptor gene was also expressed, though downregulated by comparison with in vivo levels of expression. In some lines low expression of the luteinizing hormone receptor gene could also be detected. The gene for the transcription factor GATA-1, which is expressed specifically in Sertoli cells, was expressed only in a subset of the cell lines. Quantitative analysis of SGP-2 transcript levels by ribonuclease protection assays showed an increase at the nonpermissive temperature, whereas using a similar assay, Steel factor mRNA was shown to be expressed in amounts comparable to the in vivo situation only in two cell lines during permanent growth. In summary, cell lines that exhibit distinct Sertoli cell characteristics have been established, which may resemble different stages of phenotypic development.
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PMID:Sertoli cell lines established from H-2Kb-tsA58 transgenic mice differentially regulate the expression of cell-specific genes. 866 Sep 30

The technique of site-directed mutagenesis has proven to be quite powerful in elucidating contact sites involved in the interaction of the heterodimeric glycoprotein hormones and their respective seven transmembrane (TM) G protein-coupled receptors. Our laboratory has focused on identification of the minimum core sequences of the alpha and beta subunits required for bioactivity, the minimum length of a conjoined (yoked) single-chain hCG, the amino acid residues on hCG and the LH/CG-receptor (LH/CG-R) responsible for high-affinity binding, and the regions of the receptor that are involved in TM signaling. A number of amino acid residues have been mapped on the alpha and beta subunits of hCG that appear important in receptor binding. When projected onto the crystal structure of HF-treated hCG, these residues, by and large, cluster on one side of the molecule and cover a sizeable surface area, indicating that the hormone-receptor binding interface is rather extensive. Based on mutagenesis studies of several conserved ionizable amino acid residues in the extracellular domain (ECD) of LH/CG-R and a model that we, in collaboration with Drs Lapthorn and Isaacs, have developed for this region based on the crystal structure of porcine ribonuclease inhibitor, a charged region that appears to play an important role in hormone-receptor recognition has been identified. We have also delineated several regions of LH/CG-R that do not appear to participate in hCG binding but are involved in hCG-mediated signaling. These regions are located in the ECD and extracellular loop III just prior to entry into the membrane via TM helices I and VII, respectively, and in TM helices VI and VII. Similarly, a homologous region in the ECD of the FSH receptor, located with ten residues of TM helix I, is important in signaling but not hormone binding. These results suggest that ligand binding and ligand-mediated receptor activation are quasi-distinct, albeit sequential phenomena. Collectively, our mutagenesis and modeling studies, coupled with results from other laboratories, argue for a ligand-induced conformational change of the receptor that may involve a relative reorientation of the TM helices.
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PMID:hCG-receptor binding and transmembrane signaling. 902 43

Targeted disruption of the mouse estrogen receptor-alpha gene (estrogen receptor-alpha knockout; ERKO) results in a highly novel ovarian phenotype in the adult. The ERKO mouse model was used to characterize ER alpha-dependent processes in the ovary. Visualization of the ovaries of 10-, 20-, and 50-day-old wild-type (WT) and ERKO mice showed that the ERKO phenotype developed between 20 and 50 days of age. Developmental progression through the primordial, primary, and antral follicle stages appeared normal, but functional maturation of preovulatory follicles was arrested resulting in atresia or in anovulatory follicles, which in many cases formed large, hemorrhagic cysts. Corpora lutea were absent, which also indicates that the normal biochemical and mechanical processes that accomplish ovulation were compromised. Northern and ribonuclease protection analyses indicated that ERKO ovary FSH receptor (FSHR) messenger RNA (mRNA) expression was approximately 4-fold greater than in WT controls. Ovarian LH receptor (LHR) mRNA expression was also higher in the ERKO animals. Cellular localization studies by in situ hybridization analysis of ERKO ovaries showed a high level of LHR mRNA expression in the granulosa and thecal layers of virtually all the antral follicles. Ribonuclease protection analyses showed that ovarian progesterone receptor and androgen receptor mRNA expression were similar in the two groups. These results indicated that ER alpha action was not a prerequisite for LHR mRNA expression by thecal or granulosa cells or for ovarian expression of progesterone receptor mRNA. Ovarian estrogen receptor beta (ER beta) was detected immunohistochemically, was sharply compartmentalized to the granulosa cells, and was expressed approximately equally in the ERKO animals and the WT controls. In contrast, ER alpha staining was present in the thecal cells but not the granulosa cells of the WT animals. The summary findings indicate that in the adult the major cause of the ERKO phenotype is high circulating LH interacting with functional LHR of the theca and granulosa cells. These features result in a failure of the normal maturational events leading to successful ovulation and luteinization and presumably involve both hypothalamic-pituitary and intraovarian mechanisms dependent upon ER alpha action. The presence of ER beta in the granulosa cells did not rescue the phenotype of the ovary.
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PMID:Targeted disruption of the estrogen receptor-alpha gene in female mice: characterization of ovarian responses and phenotype in the adult. 1034 64