Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

COS-7 cells were transiently transfected with human thyrotropin receptor (TSHR) and dog A1 adenosine receptor (A1R) cDNA. TSH stimulated both inositol phosphate production and cyclic AMP (cAMP) accumulation in the cells. An A1 agonist, N6-(L-2-phenylisopropyl)adenosine (PIA), which is ineffective alone, significantly enhanced TSH-induced inositol phosphate production, but insignificantly inhibited TSH-induced cAMP accumulation was revealed by short-term treatment with the protein kinase C inhibitors, staurosporine and K252a, or long-term treatment with 12-myristate 13-acetate, suggesting that endogenous protein kinase C inhibits the A1R-mediated inhibition of the TSHR-adenylate cyclase system. In staurosporine-treated cells, the stimulatory and inhibitory permissive actions of PIA on TSH-induced phospholipase C and adenylate cyclase activation respectively were completely reversed by pretreatment with pertussis toxin whereas intrinsic TSH-induced effects were hardly affected by the toxin. The cross-talk between the signalling pathway for TSHR and that for A1R was not detected in a mixture of cells expressing either TSHR or A1R. We conclude that a single species of A1R, via pertussis-toxin-sensitive GTP-binding proteins, not only inhibits adenylate cyclase but also stimulates phospholipase C in collaboration with an activated TSHR within a single cell expressing both types of receptor.
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PMID:Intracellular cross-talk between thyrotropin receptor and A1 adenosine receptor in regulation of phospholipase C and adenylate cyclase in COS-7 cells transfected with their receptor genes. 770 64

Thyrotropin is the primary hormone that, via one heptahelical receptor, regulates thyroid cell functions such as secretion, specific gene expression, and growth. In human thyroid, thyrotropin receptor activation leads to stimulation of the adenylyl cyclase and phospholipase C cascades. However, the G proteins involved in thyrotropin receptor action have been only partially defined. In membranes of human thyroid gland, we immunologically identified alpha subunits of the G proteins Gs short, Gs long, Gi1, Gi2, Gi3, G(o) (Go2 and another form of Go, presumably Go1), Gq, G11, G12, and G13. Activation of the thyrotropin (TSH) receptor by bovine TSH led to increased incorporation of the photoreactive GTP analogue [alpha-32P]GTP azidoanilide into immunoprecipitated alpha subunits of all G proteins detected in thyroid membranes. This effect was receptor-dependent and not due to direct G protein stimulation because it was mimicked by TSH receptor-stimulating antibodies of patients suffering from Grave disease and was abolished by a receptor-blocking antiserum from a patient with autoimmune hypothyroidism. The TSH-induced activation of individual G proteins occurred with EC50 values of 5-50 milliunits/ml, indicating that the activated TSH receptor coupled with similar potency to different G proteins. When human thyroid slices were pretreated with pertussis toxin, the TSH receptor-mediated accumulation of cAMP increased by approximately 35% with TSH at 1 milliunits/ml, indicating that the TSH receptor coupled to Gs and G(i). Taken together, these findings show that, at least in human thyroid membranes, in which the protein is expressed at its physiological levels, the TSH receptor resembles a naturally occurring example of a general G protein-activating receptor.
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PMID:The human thyrotropin receptor: a heptahelical receptor capable of stimulating members of all four G protein families. 855 86

COS-7 cells were transiently transfected with human thyrotropin receptor and dog A1 adenosine receptor cDNAs. An A1 agonist, N6-(L-2-phenylisopropyl) adenosine (PIA), which is ineffective alone, enhanced the thyrotropin (TSH)-induced inositol phosphate production, reflecting phospholipase C (PLC) activation, but inhibited the TSH-induced cAMP accumulation, reflecting adenylyl cyclase inhibition. These PIA-induced actions were completely inhibited by pertussis toxin (PTX) treatment. Moreover, in the cells expressing a PTX-insensitive mutant of Gi2alpha or Gi3alpha, in which a glycine residue was substituted for a cysteine residue to be ADP-ribosylated by PTX, at the fourth position of the C terminus, PIA effectively exerted both stimulatory and inhibitory effects on the TSH-induced actions although the cells were treated with the toxin. Overexpression of the betagamma subunits of the G proteins enhanced the TSH-induced inositol phosphate production without any significant effect on the cAMP response; under these conditions, PIA did not further increase the elevated inositol phosphate response to TSH. On the contrary, overexpression of a constitutively active mutant of Gi2alpha, in which the guanosine triphosphatase activity is lost, inhibited the TSH-induced cAMP accumulation but hardly affected the inositol phosphate response; under these conditions, PIA never exerted further inhibitory effects on the cAMP response to TSH. In contrast to the case of the TSH-induced inositol phosphate response, the response to a constitutively active G11alpha mutant was not appreciably affected, and that to NaF was rather inhibited by PIA and overexpression of the betagamma subunits. Taken together, these results suggest that a single type of PTX-sensitive G protein mediates the A1 adenosine receptor-linked modulation of two signaling pathways in collaboration with an activated thyrotropin receptor; alpha subunits of the PTX-sensitive G proteins mediate the inhibitory action on adenylyl cyclase, and the betagamma subunits mediate the stimulatory action on PLC. In the case of the latter stimulatory action on PLC, the betagamma subunits may not directly activate PLC. The possible mechanism by which betagamma subunits enhance the TSH-induced PLC activation is discussed.
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PMID:Betagamma subunits of pertussis toxin-sensitive G proteins mediate A1 adenosine receptor agonist-induced activation of phospholipase C in collaboration with thyrotropin. A novel stimulatory mechanism through the cross-talk of two types of receptors. 928 15

The thyrotropin receptor (TSHR) is the major autoantigen of human Graves' disease. In order to define the antigenicity of the TSHR in a defined model, we examined the immune response of BALB/c mice to immunization with a new bioactive, recombinant preparation of the ectodomain of the murine TSHR (mTSHR-ecd). Mice (n = 10) were immunized with 25-50 microg of insect cell expressed, purified and refolded, mTSHR-ecd in alum adjuvant containing pertussis toxin, on days 0, 21, 36, 50 and 70. Control mice received wild-type baculovirus-infected insect cell protein lysate, in a similar way. After 28 days, murine serum contained high titres of antibodies specific to mTSH-ecd and their titres continued to increase over 90 days. Antibody epitope mapping, using 26 peptides spanning the human TSHR-ecd, showed that a variety of regions of the ectodomain were antigenic. The earliest epitope included aa 22-41, but later two regions of reactivity were noted clustered towards the mid portion and carboxyl terminus of the ectodomain. The murine TSHR autoantibodies (TSHR-Abs) inhibited up to 78% of the binding of labelled TSH to native TSHR, demonstrating the presence of antibodies capable of blocking the native TSHR. We showed that these TSHR antibodies acted, in vitro, as TSH blocking antibodies, inhibiting TSH-induced generation of cyclic AMP in chinese hamster ovary (CHO) cells transfected with the hTSHR. Hence, the antibody response to mTSHR-ecd was potentially antagonistic in its influence on the TSHR. Assessment of thyroid function in the immunized mice showed a fall in serum total T3 by 90 days and markedly elevated murine TSH levels (from 64.0 to 239.6 ng/ml), confirming the onset of thyroid failure. However, thyroid histology remained grossly normal. These data demonstrate that mTSHR-ecd is a potent antigen with three major immunogenic regions. The induced mTSHR-Abs blocked TSH action in vivo and reduced murine thyroid function.
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PMID:Characterization of the murine immune response to the murine TSH receptor ectodomain: induction of hypothyroidism and TSH receptor antibodies. 969 93

We studied whether bovine pituitary thyrotropin (bTSH) or human recombinant thyrotropin (rhTSH) stimulated p42/p44 mitogen-activated protein kinases (MAPKs) in Chinese hamster ovary cells expressing human thyrotropin receptor (CHO-hTSHR cells). We show that p42/p44 MAPK phosphorylation was induced by both TSH preparations at similar levels in CHO-hTSHR cells and in wild-type CHO cells. In contrast, cyclic adenosine monophosphate (cAMP) production was stimulated by TSH only in CHO-hTSHR cells, demonstrating that p42/p44 MAPK stimulation was independent of the TSH receptor. Moreover, similar results were obtained with two other cell lines: the FRTL-5 thyroid cell line and the CCL39 fibroblast cell line. Maximal stimulation of p42/p44 MAPK phosphorylation was observed after a 5- to 10-minute incubation with bTSH and rhTSH preparations. At this time, the phosphorylation of GST-Elk1 was also increased in a time- and concentration-dependent manner by bTSH preparations. The phosphorylation of p42/p44 MAPKs was abolished by PD 98059 and GF 109203X, indicating the involvement of MAPK kinases (MEK 1/2) and protein kinase C. In contrast, the activation of p42/p44 MAPKs was insensitive to H89, to cholera toxin and to pertussis toxin. These data suggest that the protein kinase A pathway was not implicated in p42/p44 MAPK activation by TSH preparations. Moreover, Gs or Gi/Go proteins do not appear to participate in p42/p44 MAPK activation. We also showed that these TSH preparations failed to induce activation of c-Jun NH2 terminal kinase. We therefore conclude that the commercial TSH preparations used in this study contained factor(s) responsible for the specific activation of p42/p44 MAPKs by a TSH receptor-independent mechanism.
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PMID:The thyrotropin receptor is not involved in the activation of p42/p44 mitogen-activated protein kinases by thyrotropin preparations in Chinese hamster ovary cells expressing the human thyrotropin receptor. 1104 51