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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The initial events in prostaglandin F2 alpha-(PGF2 alpha)-induced luteolysis were studied in pregnant mare serum gonadotropin/human chorionic gonadotropin-(PMSG/hCG)-treated rats with luteinized ovaries. Injection with a potent PGF2 alpha analog (cloprostenol, 5 micrograms/ml) induced functional luteolysis, as assessed by plasma levels of progesterone and 20 alpha-dihydroprogesterone. At 0.5 and 3 h after cloprostenol administration the luteolytic effect was also evident as a reduced response of luteal adenylate cyclase to all stimulatory agents tested, LH, isoproterenol, fluoride, guanylylimidodiphosphate and forskolin. 24 h after cloprostenol the response to all agents, except to LH, had returned to normal. This general and transient block of the luteal adenylate cyclase system indicates that a common factor, possibly the stimulatory guanine nucleotide binding protein (Ns), is involved in the mechanism of action of PGF2 alpha. To test this hypothesis, we measured the functional coupling of the Ns protein to the beta-adrenergic receptor in luteal membranes. Binding competition curves showed a marked shift to the right in membranes prepared from rats injected with cloprostenol 0.5 and 3 h before membrane preparation, while at 24 h after cloprostenol the shift had disappeared. The total number of beta-adrenergic receptors was, however, not affected by the cloprostenol treatment. Computer analysis of the data indicates that, at 0.5 and 3 h after cloprostenol treatment, there was a reduced number of high affinity binding sites, 38 and 41%, respectively, compared to 53% for control membranes. The cellular mechanism for this action of PGF2 alpha on the Ns protein remains to be elucidated.
Mol Cell Endocrinol 1986 Dec
PMID:Mechanism of action of prostaglandin F2 alpha-induced luteolysis: evidence for a rapid effect on the guanine nucleotide binding regulatory component of adenylate cyclase in rat luteal tissue. 302 73

A major problem in ovarian physiology is the lack of conveniently quantifiable markers of atresia. Towards this end, we identified a monoclonal antibody (anti-OA-2) that selectively recognizes granulosa cells in atretic follicles. When cryostat sections of rat ovaries were incubated with anti-OA-2, granulosa cells in atretic follicles showed intense immunofluorescent labeling. In contrast, no anti-OA-2 immunoreactivity was observed in the granulosa of the healthy follicles. The amount of anti-OA-2 binding was significantly enhanced when atresia was stimulated by treatment with human chorionic gonadotropin, testosterone, or estrogen withdrawal. The results of immunoprecipitation and Western blot analyses indicated that the OA-2 antigen is a 39 kDa protein which is actively synthesized by the granulosa during atresia. The 39 kDa protein is localized at or near the inner surface of the plasma membrane. We conclude that the anti-OA-2 monoclonal will prove useful as a convenient analytical tool to study the regulation of granulosa atresia.
Mol Cell Endocrinol 1988 Dec
PMID:A monoclonal antibody recognizes a 39 kDa protein expressed in atretic granulosa cells. 306 68

Luteinizing hormone, follicle-stimulating hormone, and thyroid-stimulating hormone from pituitary and chorionic gonadotropin from placenta are a family of glycoproteins, each consisting of an alpha and beta subunit. Within an animal species, the alpha subunit of all four hormones contains the identical amino acid sequence, while each beta subunit is distinct and confers biologic specificity to the hormone dimer. Despite sharing common alpha subunits, these hormones bear Asn-linked oligosaccharides which differ in structure. Whereas chorionic gonadotropin contains exclusively neutral and sialylated oligosaccharides, the pituitary hormones bear neutral, sialylated, sulfated, and sialylated/sulfated structures. The sulfated oligosaccharides are unique in structure and are more prevalent on certain pituitary hormones, indicating that the synthesis of these unusual oligosaccharides is tightly regulated. The differences in oligosaccharide structures in conjunction with the highly specific endocrine responses elicited by these hormones, suggest an important functional role for the oligosaccharides, such as metabolic clearance, control of hormone response, modulation of hormone potency, and/or intracellular sorting of hormones into separate secretory granules.
Mol Cell Biochem
PMID:Differential processing of Asn-linked oligosaccharides on pituitary glycoprotein hormones: implications for biologic function. 310 43

We studied the role of luteinising hormone (LH) and human chorionic gonadotropin (hCG) in regulation of rat granulosa cell inhibin production. Whereas pregnant mare serum gonadotropin (PMSG) or purified rat follicle-stimulating hormone (FSH) stimulated inhibin accumulation in culture media up to 6-fold in a dose-dependent manner, hCG or LH alone were without significant effect. Concomitant addition of hCG or LH to cultures containing half maximal or maximal stimulating concentrations of PMSG did, however, result in a dose-dependent inhibition of PMSG/FSH-induced inhibin production. However, in the 2-step culture system a biphasic effect of hCG treatment on FSH-primed granulosa cell inhibin and progesterone production was evident. hCG was only inhibitory when the cells in the 2-step system were primed with PMSG. These data indicate that granulosa cell inhibin production is under direct control of both FSH and LH, and provide a possible explanation for alterations in inhibin activity around the time of ovulation in vivo.
Mol Cell Endocrinol 1988 Mar
PMID:Selective control of rat granulosa cell inhibin production by FSH and LH in vitro. 313 Nov 68

Male sexual differentiation is dependent upon the induction of testosterone synthesis by the fetal testis at a critical phase of development. In the rabbit, testosterone synthesis by the fetal testis is initiated after 17.5-18 days of gestation, reaches peak values by day 21 and subsequently declines. In the present study, we analyzed the specific activity and concentration of immunoreactive cholesterol side chain cleavage cytochrome P-450 (cytochrome P-450scc) in the fetal rabbit testis during development to assess its possible role as a key regulatory enzyme in fetal testicular steroidogenesis. The effects of human chorionic gonadotropin (hCG) and dibutyryl cyclic AMP on the specific activity and synthesis of cytochrome P-450scc in fetal rabbit testes in vitro also were evaluated. We observed that changes in cholesterol side chain cleavage activity paralleled the induction of testosterone synthesis; the specific activity of this enzyme which was approximately equal to 0.25 pmol min-1 mg-1 protein in testes from 19-day fetal rabbits was increased approximately equal to 10-fold in testes of 21-day fetuses and thereafter declined dramatically. Immunoreactive cytochrome P-450scc, which was first detectable in gonads of 19-day fetal rabbits, was induced markedly in 21-day fetal testes, reached maximum levels on day 24 and declined slightly thereafter. Incubation of testes from 19- and 21-day gestational age fetal rabbits with hCG or dibutyryl cyclic AMP for 24 h resulted in an induction of testosterone synthesis, cholesterol side chain cleavage activity and synthesis of cytochrome P-450scc. These findings are suggestive that androgen synthesis by the fetal Leydig cell is mediated by an induction of the synthesis and specific activity of cytochrome P-450scc. In addition, these data support the hypothesis that the developmental changes in the synthesis of cytochrome P-450scc are regulated by fetal gonadotropin and are mediated by cyclic AMP.
Mol Cell Endocrinol 1988 Feb
PMID:Developmental and hormonal regulation of cholesterol side chain cleavage cytochrome P-450 in the fetal rabbit testis. 335 1

The present study was performed to evaluate the relationship between the antagonist effect and the conformation of deglycosylated human chorionic gonadotropin (DGhCG) on the Leydig cell lutropin receptors. The maximum binding of [125I]DGhCG to anti-hCG beta antibody was decreased by 50%, while its binding profile to anti-hCG, anti-DGhCG and anti-hCG alpha antibodies remained unchanged, suggesting conformational changes in the beta subunit of DGhCG. However, the association of [125I]DGhCG to the binding sites of the receptors was much faster than that of [125I]hCG, and the ligand reached the binding equilibrium at 4 and 37 degrees C for 3 h and 15-30 min, respectively. Thus, the conformational changes in the beta subunit were not accompanied by loss of its receptor binding ability. The agonist properties of DGhCG which was bound to the receptors was fully restored by the addition of anti-hCG beta subunit antibody, while anti-hCG or anti-DGhCG restored only about 30% of the full agonist activity. This was probably due to a change of the conformation of the beta subunit to make it similar to that of the intact hormone. This restoration caused by anti-hCG beta was partially prevented by anti-hCG alpha. These facts indicate that some conformational change only in the beta subunit, not in the alpha subunit, of the deglycosylated hormone bound to the receptors is essential for the restoration of agonist properties.
Mol Cell Endocrinol 1988 May
PMID:Conformation of the beta subunit of deglycosylated human chorionic gonadotropin in the interaction at receptor sites. 339 56

This study was designed to examine the ability of in vivo administration of human chorionic gonadotropin (hCG, 4000 IU) to alter the effects of Lutalyse (PGF2 alpha, 10 mg) in the cow. hCG significantly increased plasma progesterone concentration in midcycle cows (P less than 0.01), but these elevated levels were not maintained in the presence of Lutalyse (P less than 0.05). Responsiveness of luteal cells in vitro to luteinizing hormone (LH) (100 ng/ml), prostaglandin F2 alpha (PGF2 alpha) (1 microgram/ml), dibutyryl cyclic AMP (dbcAMP) (10 mM) and PGF2 alpha (1 microgram/ml) + dbcAMP (10 mM) during a 2 h incubation was significantly reduced following in vivo treatment with Lutalyse when compared to in vivo untreated animals. In conclusion, the luteotropic effects of hCG were incapable of preventing Lutalyse-induced regression of the corpus luteum, and treatment of animals with hCG prior to Lutalyse administration could not prevent the significant decrease in responsiveness of luteal cells in vitro.
Mol Cell Endocrinol 1988 May
PMID:Interaction of hCG and Lutalyse on steroidogenesis of bovine luteal cells. 339 59

Thyrotropin (TSH) is composed of two subunits: alpha and beta. Previously, we have mapped the TSH alpha gene to human chromosome 6 and mouse chromosome 4. In this study we have located the human TSH beta gene on chromosome 1 and the mouse TSH beta gene to chromosome 3. These data suggest that the TSH beta gene lies in a conserved linkage group with the genes for amylase 1 and 2, nerve growth factor, and the protooncogene Nras.
Somat Cell Mol Genet 1986 May
PMID:Mapping thyrotropin beta subunit gene in man and mouse. 345 58

To determine if human luteinizing hormone (hLH) follows the same subcellular route in the pseudo-pregnant rat ovary as human chorionic gonadotropin (hCG), the distribution of immunoreactive and bioactive hLH within cytosol, lysosomes, and a combined plasma membrane/prelysosomal vesicle fraction was examined. Immunoreactive levels were determined using a specific radioimmunoassay and bioactive levels were determined in an in vitro Leydig cell bioassay. Low cytosolic hLH levels were apparent the first few hours after hLH administration and may reflect at least some contamination by serum and interstitial fluid. Plasma membrane/prelysosomal vesicles attained the highest hLH concentration 1 h after hLH injection, after which hLH levels declined rapidly until barely detectable levels were observed at 18 h. The hormone in this fraction was receptor bound and exhibited the highest bioactivity of the three fractions examined. Lysosomal hLH concentrations were highest at 12 after hLH injection and were maintained at high levels through 18 h. Substantial amounts of lysosomal hLH appeared to be receptor bound but this hormone was not bioactive. In situ degradation of the oligosaccharides may have occurred while lysosomal hLH was receptor bound. Lysosomal degradation is the major pathway for hLH inactivation as has been described for hCG. However, hLH may be degraded within lysosomes more quickly than hCG. The differential subcellular distribution of immunoreactive and bioactive hLH provides strong support for hLH internalization and degradation within ovarian luteal cells.
Mol Cell Endocrinol 1986 Jul
PMID:Rat ovarian subcellular compartmentalization of luteinizing hormone. 372 Oct 59

Small (15-18 microns) and large (18-45 microns) luteal cells were obtained from bovine corpora lutea of pregnancy by centrifugal elutriation of enzymatically dispersed luteal cells. Small luteal cells accounted for about 85% and large luteal cells for 8-12% of total luteal cell population. Small luteal cells were characterized by a low cytoplasmic/nuclear ratio with cytoplasm containing mitochondria, lysosomes, lipid droplets, dense granules and endoplasmic reticulum. Large luteal cells possessed a higher cytoplasmic/nuclear ratio with cytoplasm containing more abundant mitochondria, lipid droplets, dense granules and lysosomes compared to small luteal cells. Some of the mitochondria were very long. Both small and large luteal cells contained scarce amounts of Golgi elements. Dense granules were found close to the nucleus in both cell types. The nucleus of both cell types was acentric, irregular in shape and contained a well-defined nucleolus. The highly condensed chromatin in small luteal cells was found at the nuclear periphery and in the central region. Dispersed chromatin was found throughout the nucleus with condensed chromatin at the nuclear periphery of large luteal cells. Macrophages and fibroblasts were occasionally found in small luteal cell preparations, but their morphology was quite distinct from both small and large luteal cells. Scanning electron microscopy revealed that the majority of the small and large luteal cells were spherical or slightly elongated in shape. Small luteal cells displayed the presence of blebs, ruffles and short microvilli. Large luteal cell surface contained ruffles and randomly distributed clusters of blebs of different sizes, predominantly spherical in shape with a smooth surface. Finger-like projections were also occasionally seen. Small luteal cells contained significantly lower amounts of protein, but the ratios between protein and DNA were similar in both cell types. The basal, human chorionic gonadotropin (hCG)- or cyclic AMP-stimulated progesterone production, the apparent dissociation constants for [125I]hCG binding and the apparent total number of available sites per cell were similar in small and large luteal cells. The activities of enzymes that are involved directly or indirectly in progesterone biosynthesis and those involved in general cellular metabolism and biosynthesis were also similar in small and large luteal cells with one exception. That is, the activities of 5'-nucleotidase and NADH cytochrome c reductase were significantly higher in small compared to large luteal cells.
Mol Cell Endocrinol 1984 Aug
PMID:Morphological and biochemical characterization of small and large bovine luteal cells during pregnancy. 608 29


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