Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Granulosa cell lines, transformed by SV40 T-antigen and Ha-ras oncogene, have recently been established that can produce progesterone at levels comparable to those of highly differentiated cultures of primary granulosa cells (1-4). Here, the hypothesis that these cells contain a mitochondrial benzodiazepine receptor, and that stimulation of the receptor can trigger progesterone production in these cells, was tested. The agonist of the peripheral benzodiazepine receptor, Ro5-4864, produced a 3- to 5-fold stimulation (P less than 0.005) of progesterone production both in differentiated granulosa primary cultures and in the oncogene-transformed cell lines. Ro5-2807 (diazepam, Valium) exerts a similar effect on granulosa cell steroidogenesis while the specific agonist of central benzodiazepine receptor Ro15-4513 was without effect. The effects of Ro5-4864 or Ro5-2807 were not additive to those of gonadotropins and cAMP. Intact isolated mitochondria possessed high-affinity binding sites to [3H]-Ro5-4864 (Kd = 3.03 +/- 0.70 nM), which were enriched by 1 order of magnitude in these organelles compared to total cell homogenate. Bound Ro5-4864 could be competitively displaced with 1 microM unlabeled Ro5-4864 and Ro5-2807, but not with specific ligands of central benzodiazepine receptors Ro15-4513 and Ro15-1788. Prolonged elevation of cAMP in these cells caused a 30% (P less than 0.01) rise in the number of receptors. Mitochondria of NIH 3T3 cells contained only 30-40% (P less than 0.001) of the Ro5-4864 binding sites of mitochondria from steroidogenic cells, whereas yeast mitochondria lacked them completely. The existence of functional peripheral benzodiazepine receptors in mitochondria suggests that they may have a physiological role in the mobilization of cholesterol into mitochondria, and in elevating progesterone production in ovarian cells. The modulation of the interaction between benzodiazepine compounds and the gamma-aminobutyric acid receptor by progesterone metabolites suggests new interrelationships between peripheral and central nervous system receptors sensitive to benzodiazepines.
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PMID:An inducible functional peripheral benzodiazepine receptor in mitochondria of steroidogenic granulosa cells. 164 7

Diazepam binding inhibitor (DBI) is a 9-kDa polypeptide that was initially isolated from rat brain and subsequently found to be present in several peripheral tissues. DBI is particularly abundant in steroidogenic tissues, such as the adrenal glands and testes, which also contain a high concentration of peripheral/mitochondrial benzodiazepine receptors (MBRs). Because occupancy of adrenal MBRs with DBI results in increased steroidogenesis, we have investigated the relation between ACTH, DBI, and the MBR in the rat adrenal glands. Evidence presented here indicates that both the amount of DBI and its rate of synthesis in the adrenal cortex are under the control of ACTH. Seven and 9 days after hypophysectomy, the amount of DBI-like immunoreactivity (DBI-LI) in rat adrenal glands decreased dramatically from approximately 80 to 15 ng/mg tissue. The administration of single dose of ACTH (ACTH residues 1-39; 200 mU/kg, iv) or repeated doses of ACTH-R (ACTH in saline containing 16% gelatin; 15 U/kg, sc, twice daily) reduced the decrease in adrenal DBI-LI caused by hypophysectomy. In hypophysectomized rats (7 days after hypophysectomy) the increases in both adrenal DBI-LI and plasma corticosterone induced by ACTH 1 h after a single injection (200 mU/kg, iv) were inhibited by injection of cycloheximide (40 mg/kg, ip) 10 min after ACTH. However, cycloheximide at this dose had no effect on the ACTH-induced increase in adrenal cAMP concentration or the number of affinity of MBRs for 4'-[3H]chlorodiazepam.
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PMID:Regulation of diazepam binding inhibitor in rat adrenal gland by adrenocorticotropin. 164 41

It has been reported that the addition of antibody (Ab) against human immunoglobulin G (IgG) converts TSH receptor-bound blocking-type IgG to stimulating-type IgG. However, the detail of converting mechanism remains unclear. In this study we examined the mechanism involved in this conversion using FRTL-5 cells. Blocking-type IgG was obtained from a patient with hypothyroidism. FRTL-5 cells were first incubated with IgG solution, then washed with PBS and exposed to antihuman IgG Ab. The effect of antihuman IgG Ab on converting activity was dose dependent. Maximal stimulation of cAMP was achieved with an antiserum dilution of 1:75. It seems likely that antimicrosomal Ab does not interfere with cAMP production, since IgG with a high anti-hemagglutination antibody titer did not show converting activity. Of the several kinds of antibodies tested, Ab against human IgG-Fab fragment was the most effective in converting ability, while the least effective were those against human IgG-Fc fragment. Although the divalent F(ab')2 fragment of antihuman IgG was significantly more effective in its converting ability than the monovalent Fab fragment, the Fab fragment itself also converted blocking IgG to the stimulating type in a dose-dependent manner. Accordingly, receptor cross-linking or aggregation does not play a major role in promoting this converting phenomenon. When cells were first exposed to blocking-type IgG and then to both antihuman IgG Ab and bovine TSH, cAMP production was much greater than the sum of each alone. However, anti-IgG Ab alone did not affect the binding of blocking-type IgG to receptor. These results suggest that the addition of antihuman IgG Ab not only converts blocking-type IgG to the stimulating type but also recovers TSH activity via a postreceptor step. Forskolin, like TSH, showed an additive effect on cAMP stimulatory action with antihuman IgG. In contrast, cholera toxin and antihuman IgG Ab were not additive. The reason for this discrepancy remains unknown. In summary, our observation indicates that 1) the converting phenomenon is induced via IgG-TSH receptor complexes; 2) the mechanism aside from receptor aggregation, i.e. the recognition of a critical domain in TSH receptor molecule, seems necessary for promoting converting phenomenon; and 3) the addition of antihuman IgG Ab affects a postreceptor step via TSH receptor structures that differ from the TSH-binding site.
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PMID:The mechanism involved in the conversion of thyrotropin receptor-bound blocking-type immunoglobulin G (IgG) to the stimulating-type by anti-human IgG antibodies. 215 26

Monolayer cultures of human thyroid cells derived from thyroid adenoma were utilized for the assay of thyroid stimulating substances such as thyrotropin (TSH), cholera toxin and thyroid stimulating immunoglobulin (TSI) in patients with Graves' disease. Adenoma cells were treated with 0.1% collagenase or 2000 unit/ml dispase to thyrocytes. The cells were cultured in MEM containing 10% fetal calf serum under an atmosphere of 5% CO2 in air. Within 24 hours, the cells attached themselves to the plastic surface and formed a monolayer. Cyclic AMP responses to TSH, cholera toxin or Graves' IgG were tested in a medium (PBS) containing 0.5 mM IBMX. The cyclic AMP responses to TSH were generally maximal on the 3rd day of culture and declined thereafter. The response was dose-dependent, and 10 microU/ml of TSH produced a significant increase of cellular cyclic AMP. The response by 1 microU/ml of TSH was 28 approximately 57 fold above the basal. The response was also a function of the incubation period. The maximal response was attained after 1 h incubation. When the cultures were washed after exposure to TSH, the cellular cyclic AMP levels rapidly declined, suggesting that removal of receptor-bound TSH results in a prompt cessation of cyclic AMP production. The thyroid cells in monolayer also responded to cholera toxin. The response was dose-dependent, and cholera toxin as low as 1 ng/ml was able to increase cyclic AMP production. In contrast to the observations in TSH, the cyclic AMP responses induced by cholera were hardly affected by washing the cultures after exposure to cholera toxin. Treatment of the cells with cholera toxin for only 3 min resulted in a continuous stimulation of cyclic AMP production for more than 4 hours. Confirming recent observations by others, most of Graves' IgG stimulated cyclic AMP production in a dose-dependent manner, but some of them inhibited the response at high concentrations. IgG derived from normal subjects did not increase cellular cyclic AMP. The time course in the cyclic AMP responses induced by Graves' IgG was variable among the IgG preparations from different patients. In some patients, the maximal responses were attained after 4 hours of incubation. A significant difference was noted between TSH and Graves' IgG in the stimulation of cyclic AMP production after washing the cultures. When the cultures were treated with Graves' IgG for 30 min, washed and then incubated without Graves' IgG, cellular cyclic AMP levels remained at the levels which were almost equivalent to those observed in the continuous presence of the IgGs.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[The effects of TSH, cholera toxin and Graves' IgG on cAMP production in cultured human thyroid adenoma cells in monolayer]. 286 66

The protein B of group B streptococci can bind in a nonimmune reaction to Ig of the IgG and IgM classes of various mammalian species (i.e., human, mouse, rabbit, and bovine). Protein B binding involves the Fc parts of both IgG and IgM molecules. Monoclonal or polyclonal IgG or IgM and the IgM-FC5 mu fragment of human myeloma protein combined with the protein B thereby inhibiting protein B-induced hemolysis in the CAMP reaction. The protein B/Ig complex can be dissociated with 1% Triton or guanidine-HCl (6 M). Mice infected intraperitoneally with sublethal doses of group B streptococci (GBS) and that received seven repeated intravenous injections of highly purified protein B during the first 9 h of infection developed fatal septicemia within 24 h with colony counts of up to 10(8) CFU/ml in the blood. Animals treated in the same way with either PBS or trypsinized protein B recovered. The protein B itself was not pathogenic when injected into healthy mice. Tissue sections of liver or spleen from mice infected with a lethal dose of GBS revealed the presence of protein B together with large numbers of cocci when stained by the peroxidase method using specific antibodies raised against purified protein B in the rabbit.
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PMID:Unspecific binding of group B streptococcal cocytolysin (CAMP factor) to immunoglobulins and its possible role in pathogenicity. 354 80

The possibility that prostaglandin E2 (PGE2) increases endometrial vascular permeability and initiates decidualization in sensitized rat uteri by stimulation of adenosine 3':5'-cyclic monophosphate (cAMP) synthesis was investigated. Immature rats, pretreated so that they were sensitized for the decidual cell reaction, were used. Following the unilateral intrauterine injection of 50 microliters phosphate-buffered saline containing gelatin (PBS-G), a deciduogenic stimulus, uterine concentrations of both PGE and cAMP were elevated as early as 1 min after the intrauterine treatment. To determine if uterine stimuli which increase endometrial vascular permeability also increase uterine cAMP concentrations, rats, treated with or without indomethacin, an inhibitor of PG synthesis, received unilateral intrauterine injections of 50 microliters PBS-G with and without 10 micrograms PGE2 and were killed 15 min later. Uterine cAMP concentrations were elevated in all injected horns except in those of indomethacin-treated rats receiving PBS-G intraluminally, thus paralleling the expected changes in endometrial vascular permeability. As indicated by radioactivity levels in the stimulated horn 15 min after the i.v. injection of 125I-labeled bovine serum albumin, the intrauterine injection of dibutyryl cAMP, with or without theophylline, did not increase endometrial vascular permeability in indomethacin-treated animals. In contrast, cholera toxin, an activator of adenylate cyclase activity, markedly elevated permeability and induced decidualization. Except for the lack of a permeability response to the cAMP analogue, these data are consistent with the hypothesis that the effect of PGE2 on endometrial vascular permeability is mediated by cAMP.
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PMID:Prostaglandin E2, adenosine 3':5'-cyclic monophosphate and changes in endometrial vascular permeability in rat uteri sensitized for the decidual cell reaction. 631 67

The effect of prostaglandin E2 (PGE2), on the intracellular pH (pHi) in BCECF-loaded Madin Darby Canine Kidney (MDCK) cells was investigated. PGE2 elevated the pHi. Under resting conditions, pHi of MDCK cells suspended in PBS at pH 7.4 was 7.11 +/- 0.08; PGE2 increased pHi with an EC50 of 0.16 microM. PGF2 alpha elicited a similar response to PGE2, with an EC50 of 0.24 microM. Amiloride (0.4 mM) reversed the response to PGE2 (control 7.18 +/- 0.05; PGE2 7.26 +/- 0.05; after amiloride 7.18 +/- 0.05). In MDCK cells exposed to a Na(+)-free solution, alkalinization induced by this eicosanoid was blocked (Ringer-choline 7.16 +/- 0.03; PGE2 7.16 +/- 0.02). PGE2 increased by 100% the rate of recovery after an acidification pulse with ammonium chloride. In the presence of Ringer-HCO3- (pH 7.4), there was a delay in the maximal response to this prostaglandin (PBS 2.2 +/- 0.27, Ringer-bicarbonate 3.4 +/- 0.55 min) and the pHi increment was less marked than in PBS (0.09 pH units in HCO3- versus 0.16 pH units in PBS; P < 0.001). This effect of PGE2 was not blocked by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (1.0 mM). PMA (100 nM), activator of protein kinase C, mimicked the response to PGE2, suggesting the participation of this kinase on the effect of the prostanoid. As expected, two inhibitors of protein kinase C, staurosporine and sphingosine, abolished the response to PGE2. Staurosporine (0.10 microM), an inhibitor of protein kinase C, blocked the response to PGE2 (control 7.02 +/- 0.04; PGE2 and staurosporine 7.03 +/- 0.04, n = 9, not significant). Sphingosine, another inhibitor of protein kinase C, also blocked the response to PGE2. Two analogues of cAMP did not modify the pHi. In summary, PGE2 induced an intracellular alkalinization via stimulation of a Na+/H+ exchanger, with the participation of protein kinase C, in MDCK cells.
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PMID:Induction of alkalinization in cultured renal cells (MDCK line) by prostaglandin E2. 748 Jul 99

Steroid biosynthesis activated by pituitary tropic hormones is known to be acutely regulated by cAMP acting via Protein kinase A. Because the mitochondrial benzodiazepine receptor (MBR) has been suggested to play a role in the activation of steroidogenesis, the present study investigates whether various protein kinases phosphorylate MBR. In rat and bovine adrenal mitochondrial preparations Protein kinase A, but not other purified protein kinases, was found to phosphorylate the 18 kDa MBR protein. In digitonin-permeabilized MA-10 Leydig tumor cells incubated with [gamma-32P]ATP, phosphorylation of MBR was detectable during treatment of the cells with dibutyryl cAMP. In conclusion, these data show that the MBR protein is an in vitro and in situ substrate of Protein kinase A, but the role of this phosphorylation in the regulation of steroidogenesis remains to be established.
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PMID:Studies on the phosphorylation of the 18 kDa mitochondrial benzodiazepine receptor protein. 808 66

The motility, acrosome integrity and fertility of ram spermatozoa were examined after treatment with five compounds (caffeine, pentoxifylline, cAMP, 2-deoxyadenosine and kallikrein). Semen was extended with a Tris-based medium and frozen in pellet form. The compounds were added at various concentrations to the semen before freezing or after thawing. Motility and acrosome characteristics were assessed over a 6-h post-thaw period of incubation at 37 degrees C. Of the five compounds examined, only pentoxifylline, when added after thawing, stimulated motility but had not effect on the acrosome integrity of spermatozoa. Pregnancy rates for ewes inseminated in the uterus with semen treated after thawing with Dulbecco's phosphate-buffered saline (PBS, control) or PBS containing pentoxifylline (15 mM in the thawed semen), were 16/39 (41%) and 22/42 (52%) respectively. Motility characteristics of spermatozoa assessed by image analysis (Hamilton-Thorne analyser) were initially better after treatment of thawed semen with pentoxifylline than with PBS ("percent motility', "percent progressive motility', "percent rapid', "percent moderate' and "percent static', P < 0.01 or P < 0.001), but there was a greater deterioration in these characteristics during post-thaw incubation in semen treated with pentoxifylline than in the controls. The deterioration in motility characteristics occurred within 4 h of thawing and this may have been responsible for the modest improvement in fertility of spermatozoa treated with pentoxifylline.
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PMID:Motility, acrosome integrity and fertility of frozen ram spermatozoa treated with caffeine, pentoxifylline, cAMP, 2-deoxyadenosine and kallikrein. 884 74

Effects of FSH on ovarian follicular development can be modulated by factors present in serum or by locally produced factors in follicular fluid. Some of these factors may act directly on the FSH receptor. A Chinese hamster ovary cell line (CHO-F3B4) stably transfected with the human FSH receptor has been used to measure the effects of these modulators on FSH-stimulated adenylate cyclase activity. After incubation of CHO-F3B4 cells with human recombinant FSH (recFSH) for 4 h, cAMP levels were elevated 100-230 times above basal levels (ED50 24.9 mU/ml recFSH). cAMP production was inhibited after the addition of increasing amounts (up to 90% of the incubation volume) of hypogonadotrophic human serum (HS) at a fixed stimulatory dose of 30 mU/ml recFSH. At 10% HS the cAMP response was diminished to approximately 40-60% of the original value, whereas at a concentration of 90% HS the cAMP values were diminished to 30%. Effects of serum components on cell viability could be excluded, since forskolin- and cholera-toxin-stimulated cAMP production were not affected by preincubation of the cells in the presence of HS. The FSH-stimulated oestradiol production in rat Sertoli cells, which has been used frequently for in vitro bioassays of FSH, was almost completely inhibited by the addition of human serum, suggesting that serum has more pronounced effects on events downstream of receptor activation. Various specific FSH binding inhibitors have been demonstrated by radioreceptor assays to be present in serum. In order to assess whether such FSH receptor binding inhibitors would also inhibit receptor activation, the specific conditions used in the radioreceptor assays (buffers of low ionic strength) were also used to measure the effects of serum on FSH receptor activation. Under these conditions (a low-salt buffer, corrected for low osmolarity with 200 mM sucrose), CHO-F3B4 cells responded to FSH stimulation in a similar way to that observed in normal buffers. When CHO-F3B4 cells were incubated in this low-salt buffer with a fixed low dose of FSH (3 mU/ml), the addition of 3-90% (v/v) dialysed HS inhibited the FSH-stimulated cAMP accumulation to a similar extent to that in standard conditions. The observed inhibition of adenylate cyclase activation by the low-molecular-mass fraction (< 10 kDa) of HS could be attributed to the presence of salts in this fraction, since the addition of PBS in similar concentrations displayed an equal degree of inhibition. It is concluded that the inhibitory effects of serum on FSH-stimulated cAMP production in CHO-F3B4 cells are small, compared with the inhibition of aromatase induction in rat Sertoli cells. The strong inhibition of aromatase in rat Sertoli cells may result from the effects of serum acting on the FSH receptors as well as on other pathways not related to the FSH receptor. Therefore, measurement of aromatase in Sertoli cells is not suitable for the detection of inhibitors of FSH receptor activation. The CHO-F3B4 cells are useful for the measurement of whether inhibition of FSH receptor activation occurs in serum or follicular fluid from patients with disturbed follicle development.
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PMID:Application of a CHO cell line transfected with the human FSH receptor for the measurement of specific FSH receptor activation inhibitors in human serum. 888 70


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