Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the effects of steroidogenesis inducing protein (SIP) (Endocrinology (1990) 126, 3043-3052) on steroid production in MA-10 mouse Leydig tumor cells. Our results indicate that SIP results in the stimulation of progesterone production in MA-10 cells to the same extent obtained when maximal doses of luteinizing hormone (LH), human chorionic gonadotropin (hCG) and dibutyryl cAMP (dbcAMP) are used. It was also observed that the increased progesterone production in response to SIP was not accompanied by an increase in intracellular cAMP levels as was seen following hCG stimulation. In addition, stimulation of progesterone production using maximal doses of LH, hCG and dbcAMP could be further increased by the addition of SIP to the incubation medium also indicating that this steroidogenic activity was acting through a differential signal transducing system than these hormones. That SIP was not acting through the cAMP second messenger pathway was also demonstrated by its lack of sensitivity to the neutralizing effects of a monoclonal antibody to LH as well as by its insensitivity to the protein kinase A inhibitor HA 1004 while both of these treatments significantly decreased LH and hCG stimulated steroid production. Lastly, SIP was unable to elicit the induction of several mitochondrial proteins which have previously been shown to be synthesized in MA-10 cells in response to LH, hCG and dbcAMP. Our results indicate that SIP stimulates the production of high levels of steroids through a signal transduction pathway which is distinct from that employed by trophic hormone stimulation in Leydig cells.
Mol Cell Endocrinol 1992 Apr
PMID:Effects of steroidogenesis inducing protein (SIP) on steroid production in MA-10 mouse Leydig tumor cells: utilization of a non-cAMP second messenger pathway. 131 53

c-Fos and c-jun are immediate early proto-oncogenes encoding proteins for the heterodimer AP-1, a DNA binding complex which regulates gene transcription. In order to investigate the presence and potential gonadotropin regulation of mRNAs for these proto-oncogenes in rat granulosa cells, we used Northern blotting of total RNA from cultured cells. Granulosa cells obtained from diethylstilbestrol (DES)-treated weanling rats were challenged with follicle-stimulating hormone (FSH), luteinizing hormone (LH), human chorionic gonadotropin (hCG), dibutyryl cAMP ((Bu)2cAMP) or tetradecanoyl-13-phorbol acetate (TPA) either 2.5 h after cell isolation (day 0) or following a 2-day pretreatment with FSH (day 2). Freshly isolated cells treated with FSH exhibited 4-fold and 3-fold increases in c-fos and c-jun mRNAs, respectively, within 30 min. Two hours after FSH treatment, both c-fos and c-jun message levels diminished to near control levels. Granulosa cells pretreated for 2 days with FSH, then re-challenged with FSH, showed similar increases in both c-fos and c-jun messages. These effects were dose- and time-dependent on both day 0 and day 2. Likewise, (Bu)2cAMP also increased c-fos and c-jun mRNAs in a time- and dose-dependent manner on both day 0 and day 2. In contrast, LH or hCG minimally increased c-fos and c-jun mRNAs on day 0, but on day 2, both hormones markedly increased message levels in a manner similar to that seen with FSH. Analogous effects were observed with TPA which minimally stimulated c-fos and c-jun mRNAs on day 0, but markedly increased these messages on day 2. These studies demonstrate that c-fos and c-jun mRNAs can be induced in cultured rat granulosa cells by acute gonadotropin, (Bu)2cAMP or phorbol ester treatment and suggest that these immediate early proto-oncogenes may play a role in granulosa cell function.
Mol Cell Endocrinol 1992 Dec
PMID:Gonadotropin regulation of c-fos and c-jun messenger ribonucleic acids in cultured rat granulosa cells. 133 29

Luteinizing hormone/chorionic gonadotropin (LH/CG) receptor complementary DNA (cDNA) isoforms were amplified using pseudopregnant rat ovarian total RNA as a template and the primers reaching over the coding regions at both ends in a reverse transcriptase-polymerase chain reaction (RT-PCR). Agarose gel electrophoresis of the PCR products revealed three bands corresponding to about 2.1, 2.0 and 1.8 kilobases (kb). Subcloning of pooled PCR products into EcoRI site of pUCBM20 resulted in 167 clones, from which five different restriction patterns were obtained by digestion with EcoRI and HaeIII. One clone of each was further characterized. It could be predicted from the nucleotide sequences that the clone rLHR2100 encoded a full-length receptor (a 674 amino acid mature protein), the clone rLHR2075 lacked part of exon IX (nucleotides 693-717) and encoded a truncated 225 amino acid mature protein, the clone rLHR1950 lacked exons III and IV (nucleotides 246-395) and encoded a nearly full-length protein (a 624 amino acid mature protein), and the clones rLHR1834 and rLHR1759 lacked the same part of exon XI (nucleotides 960-1225), with exon V (nucleotides 396-470) also absent in the latter, the deletion in exon XI leading both these clones to premature termination. The clone rLHR1834 encoded a 316 amino acid mature protein and rLHR1759 a 291 amino acid mature protein, respectively. The sequence data suggest that all of these isoforms contain the putative signal sequence and are derived from a single copy gene via alternative splicing. These results point further to the fact that the expression of the 90 kDa LH/CG receptor is regulated via an extensive alternative splicing of the receptor gene primary transcript.
Mol Cell Endocrinol 1992 Mar
PMID:Expression of the LH/CG receptor gene in rat ovarian tissue is regulated by an extensive alternative splicing of the primary transcript. 135 63

The glycoprotein hormones are a family of alpha beta heterodimeric proteins which are responsible for gonadal and thyroid function. In previous studies we employed chimeric glycoprotein hormone beta-subunits to identify amino acid residues critical for binding to receptors and antibodies. To facilitate similar studies of the alpha-subunit of these hormones, we assembled a 406 bp synthetic gene which encodes the human alpha-subunit leader sequence and the secreted portion of the bovine alpha-subunit. It contains unique restriction sites that can be used for cassette mutagenesis or for making human/bovine alpha-subunit chimeras. The gene was assembled from eight long oligodeoxynucleotides in a single ligation and its structure verified by DNA sequencing. Co-transfection of COS-7 cells with the synthetic gene and the cDNA for human chorionic gonadotropin (hCG) beta-subunit resulted in the secretion of a functional alpha beta heterodimer which bound to luteinizing hormone receptors. The protein was recognized by several monoclonal antibodies including B109, an antibody to a conformational epitope which binds hCG but not the free bovine alpha-, human alpha-, or hCG beta-subunits. This suggests that the binding site for B109 may be formed by residues located primarily within the hCG beta-subunit and that formation of this epitope requires a change in conformation of the beta-subunit when it combines with the alpha-subunit.
Mol Cell Endocrinol 1992 Feb
PMID:Assembly and expression of a synthetic gene encoding the bovine glycoprotein hormone alpha-subunit. 137 75

In the present investigation we sought to define the specific sites in the pathway of placental progesterone biosynthesis that underlie the action of human chorionic gonadotropin (hCG). When the cells were challenged with dibutryl cAMP (dbcAMP), forskolin or isobutylmethylxanthine, they produced significantly higher amounts of progesterone which in the presence of the hCG antibody was reduced to the level of the control set of cells. Trophoblast cells cultured in serum free medium with 25-hydroxycholesterol (25-OHC) produced increased amounts of progesterone. In the presence of hCG antibody at a concentration which neutralized the secreted hCG, the steroid production was completely blocked, even when the 25-OHC was added to the medium. Also, direct quantitation of the cytochrome P450 SCC enzyme in the absence of hCG indicated a significant decrease. The exogenous addition of low density lipoproteins (LDL) increased the progesterone secretion by the trophoblast cells in culture. Neutralization of hCG by the antibodies, however, drastically reduced the LDL induced progesterone secretion, which was restored by the addition of dbcAMP to the medium. Based on these findings, we suggest a stimulatory effect of hCG on normal trophoblast cells at the level of LDL utilization and cytochrome P450 SCC enzyme. Since dbcAMP could mimic these actions of hCG, the data suggest a possible autocrine/paracrine role of hCG on the trophoblast cells. An additive effect of hCG and cAMP on progesterone secretion observed in our studies, indicate that apart from hCG, adenylate cyclase activity may also be regulated by other factors.
J Steroid Biochem Mol Biol 1992 May
PMID:Regulation of progesterone secretion in human syncytiotrophoblast in culture by human chorionic gonadotropin. 137 14

The immune recognition of a molecule naturally presented as a monomeric or an oligomeric structure is analyzed using the human chorionic gonadotropin alpha subunit (hCG-alpha) as a model. Indeed, hCG-alpha circulates as either a free subunit or combined to the beta subunit (hCG-beta) to form the dimeric hCG hormone. A T cell study was performed in BALB/c (H-2d) mice which were found to be high responders to hCG-alpha. Mice were immunized with the free hCG-alpha or the dimeric hCG alpha/beta, and their lymph node cells were challenged in vitro with either alpha subunits from different species, hCG or peptides spanning the entire primary structure of hCG-alpha. Proliferation and IL-2 assays demonstrated that hCG-alpha-primed lymph node cells responded equally well to hCG-alpha and hCG alpha/beta, suggesting that both the free and combined hCG-alpha subunits are processed in a similar way. Among the various synthetic peptides used, only those mimicking the hCG-alpha(59-92) C-terminus portion were able to stimulate hCG-alpha-primed lymph node cells, demonstrating that this region contains immunodominant T cell recognition site(s). The hCG-alpha(23-43) and (32-59) peptides, although incapable of stimulating T cells primed with hCG-alpha, elicited a T cell response when used as immunogens. These regions encompassed cryptic epitopes which were not generated during hCG-alpha processing in H-2d mice. The T cell epitopes of hCG-alpha above described as immunodominant or cryptic on the free alpha subunit, had similar characteristics when the alpha/beta dimer was used as the immunogen. In contrast, T cells primed with peptides mimicking immunodominant sites recognized differently the hCG-alpha and the hCG alpha/beta antigens. Moreover, the analysis of the B cell response to all the immunogenic hCG-alpha peptides indicated that they bear B and T cell epitopes as well. Antibodies elicited against the hCG-alpha(59-92) or (32-59) peptide were capable of recognizing the alpha subunit in its free form but not in the alpha/beta hCG dimer. Such study deserves attention for the comprehensive mechanisms of the immune response to hCG as well as for the design of anti-hCG vaccines.
Mol Immunol
PMID:Immune recognition of a molecule naturally presented as a monomeric or an oligomeric structure: the model of the human chorionic gonadotropin alpha subunit. 137 32

A luteinising hormone receptor binding inhibitor (LHRBI) has been purified from bovine corpus luteum (CL). Steroid-free extract of the CL was subjected to successive chromatographies on Sephadex G-50, Q-Sepharose, Orange A dye and metal chelate affinity columns followed by high performance-reverse phase and gel filtration columns. Purification was monitored by the ability of the fractions to inhibit the binding of 125I-human chorionic gonadotropin (hCG) to porcine granulosa cells in vitro. The final isolate showed an 8000-fold enrichment of activity. It was also capable of inhibiting porcine granulosa cell secretion of estradiol and progesterone (P) in vitro. Administration of LHRBI into follicle-stimulating hormone (FSH)-stimulated, immature rats strongly inhibited the ovarian ovulatory response to hCG as revealed by decreased P levels and the number of ova released. The M(r) of LHRBI as assessed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis was ca. 15 kDa and the pI was between 5.0 and 5.5.
Mol Cell Endocrinol 1992 Sep
PMID:Isolation of luteinising hormone receptor binding inhibitor from bovine corpus luteum. 144 83

Previous studies have shown that basic fibroblast growth factor (bFGF) can modulate basal and luteinizing hormone/human chorionic gonadotropin (LH/hCG)-stimulated Leydig cell functions. It has not been ascertained whether these actions are due to direct or indirect effects on Leydig cells. To resolve this question, a multi-step procedure was used to isolate highly-purified Leydig cells from immature rats. 125I-bFGF binding studies were performed on cultured cells. Scatchard analysis of the data indicated a single binding site with an apparent Kd of 82 pM and a binding capacity of approximately 2800 sites per cell. Both bFGF and acidic FGF similarly were effective in displacing 125I-bFGF, suggesting that the receptor binds both bFGF and aFGF. However, neither hCG, follicle-stimulating hormone (FSH), insulin, insulin-like growth factor-1 (IGF-1), prolactin, platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) were effective competitors. When binding studies were conducted on cultured testicular interstitial cellular fractions that are normally discarded during Leydig cell purification, bFGF receptors were identified in these fractions. These results demonstrate that bFGF can have direct effects on Leydig cells through specific receptors; however, because other interstitial cell type(s) also have bFGF receptors, they stress the importance of using highly purified cells when evaluating bFGF actions on Leydig cells.
Mol Cell Endocrinol 1992 Oct
PMID:Evidence for basic fibroblast growth factor receptors in cultured immature Leydig cells. 145 39

The glycoprotein hormone human chorionic gonadotropin (hCG) is synthesized in large quantities by the developing placenta, reaching peak concentrations in maternal blood during the late first trimester and early midtrimester of pregnancy. In general it is believed that the alpha-subunit of this dimeric hormone is expressed in pituitary gonadotropes, thyrotropes, and trophoblasts, while the beta-subunit is expressed exclusively by trophoblasts. Studies from our laboratory and other laboratories have shown that some midtrimester human fetal tissues, in addition to the placenta, can synthesize proteins that appear to be very similar to the beta-subunit of hCG. To define precisely the nature of this putative hCG-beta-subunit in extraplacental fetal tissues, we have examined the mRNA from a variety of human fetal and adult tissues using nucleic acid hybridization and reverse transcription-polymerase chain reaction (PCR) methods. Our results demonstrate that midtrimester fetal kidney and adrenal tissues contain hCG-beta mRNA transcripts at concentrations comparable to that of placenta, while fetal lung, brain, muscle, and adult adrenal contain only trace to undetectable levels of hCG-beta mRNA. By restriction endonuclease mapping of PCR fragments from fetal tissue cDNAs, we show that the hCG-beta transcript expressed in midtrimester human fetal organs is a bone fide copy of hCG-beta gene No. 5 of the beta-subunit gene family located on chromosome 19.
Mol Reprod Dev 1992 Sep
PMID:Extraplacental human fetal tissues express mRNA transcripts encoding the human chorionic gonadotropin-beta subunit protein. 151 Aug 39

Electrical stimulation is known to cause activation in mammalian oocytes, possibly by eliciting an elevation in intracellular calcium (Ca2+). This study reports intracellular Ca2+ concentrations in mature rabbit oocytes using the Ca2+ indicator fura-2. Calcium levels were determined prior to, during, and after the administration of an electrical pulse (3.6 kV/cm for 60 microseconds). Baseline Ca2+ levels ranged from 30 to 90 nM. The intracellular Ca2+ transient evoked by a pulse, peaked at 11 sec, was highly variable in amplitude (40-300 nM) and returned to prepulse levels within 300 sec. Electrically stimulated oocytes did not exhibit repetitive Ca2+ transients. The size of the cytoplasmic Ca2+ rise was influenced by the duration of the pulse, the field strength and the concentrations of external Ca2+ rise was influenced by the duration of the pulse, the field strength and the concentrations of external Ca2+ (P less than 0.05). Oocytes electrically stimulated in the presence of 100 microM CaCl2, which evoked Ca2+ transients with a mean magnitude of 120 nM, activated at a higher rate (P less than 0.05) than oocytes stimulated in the presence of either higher or lower levels of external Ca2+. Although oocytes electrically shocked at 16-18 hr after administration of human chorionic gonadotropin (hphCG) activated at a lower rate than oocytes stimulated at 22-24 hphCG (P less than 0.05), their intracellular Ca2+ response to the pulse was similar (P less than 0.05). These results indicate that electrical pulse parameters and extracellular Ca2+ concentrations can be used to modulate intracellular Ca2+ levels and optimize oocyte activation rates.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1992 May
PMID:Intracellular Ca2+ response of rabbit oocytes to electrical stimulation. 151 52


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