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Matei Bolborea, Gisela Helfer, Francis J P Ebling and Perry Barrett

cyclase is a signal transduction pathway commonly associated with TSH receptor activation, but TSH receptors are known to couple with a diverse range of G proteins to activate several different pathways that potentially have multiple downstream

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M Hołysz, N Derebecka-Hołysz and W H Trzeciak

( Trzeciak & Boyd 1974 , Boyd et al . 1975 ). ACTH binds to a specific receptor coupled with membrane-bound adenylyl cyclase; thus, cAMP is generated and activates the protein kinase A (PKA) signal transduction pathway, which leads to phosphorylation and

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Baowei Jiao, Xigui Huang, Chi Bun Chan, Li Zhang, Deshou Wang and Christopher H K Cheng

substituted by an YXXFS motif. In addition, there are two conserved regions within the intracellular domain termed Box 1 and Box 2 that are important for signal transduction of the receptor. The proline-rich Box 1 region is the site of Janus kinase 2 (JAK2

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Gábor Turu and László Hunyady

this review is to discuss the intracellular mechanisms of the action of CB 1 R. After summarizing the available data about the G-protein activation and signal transduction of CB 1 R, this review also analyses recent data about dimerization or

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Gerald Thiel, Isabelle Müller and Oliver G Rössler

Islam MS 2011 TRP channels of islets. In: Transient receptor potential channels. Advances in Experimental Medicine and Biology 704 811–830 (Fig. 42.1) with kind permission from Springer Science+Business Media B.V.). Figure 3 Signal transduction of

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C Gutacker, R Flach, P Diel, G Klock and C Koch-Brandt

ABSTRACT

Clusterin (gp 80, apolipoprotein J, TRPM-2) is a widely expressed multifunctional glycoprotein. Its demonstrated and proposed functions include the transport of lipids and membrane fragments, the inhibition of the cytolytic action of the terminal complement complex and the modulation of cell—cell interactions. The expression of the gene is enhanced during tissue injury and remodelling and by hormone-withdrawal-induced apoptosis of prostate and mammary cells. We show here that, in the kidney-derived epithelial cell line MDCK, clusterin mRNA is repressed by glucocorticoids and by progesterone. Treatment with epidermal growth factor also represses clusterin gene expression in MDCK cells. Incubation with 12-O-tetradecanoyl-phorbol-13-acetate, which activates protein kinase C (PKC), induces clusterin mRNA, while chelerythrine, an inhibitor of PKC, represses clusterin gene expression, suggesting that the clusterin gene responds to signalling pathways involving PKC. These results open up the possibility of studying the complex regulation of the clusterin gene by multiple signal transduction pathways within a single cell type, and most importantly, of characterizing interactions between the individual signal transduction cascades.

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S Singh and PD Gupta

In the present study, the induction of the phosphoinositide signal transduction pathway by 17 beta-oestradiol has been demonstrated in rat vaginal epithelial cells (VEC). We have shown an increase in the metabolism of phosphoinositol lipids by 3H-myoinositol incorporation as well as production of inositol phosphate in VEC in vivo and in vitro following oestradiol administration. Concomitant changes in intracellular calcium levels have also been observed under the influence of oestradiol. To rule out the effects of cytokines, parallel studies were performed using primary cultures of VEC. Oestradiol-induced calcium uptake was seen even in the presence of actinomycin D and cycloheximide which inhibit transcription and translation respectively. Calcium uptake was blocked by neomycin, an inhibitor of phosphoinositol lipid metabolism, and by the oestrogen receptor antagonist tamoxifen. Results suggest that oestradiol induces second messenger pathways in the VEC through specific receptors. Implications of these observations in cellular differentiation processes are discussed.

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N Martínez-Micaelo, N González-Abuín, A Ardévol, M Pinent, E Petretto, J Behmoaras and M Blay

consequence of a differential regulation of the leptin signalling pathway genes, the expression of key genes involved in the regulation of leptin signal transduction in relevant organs, including the mesenteric fat pad, the hypothalamus and the liver was

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Marta Labeur, Barbara Wölfel, Johanna Stalla and Günter K Stalla

and as RA, a CRH signaling pathway inhibitor, may modulate TMEFF2, we decided to investigate in detail the effects of TMEFF2 on the signal transduction pathway of CRH. Materials and methods Cell culture and chemicals AtT20 pituitary corticotrope tumor

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M. C. Slootweg, R. P. de Groot, M. P. M. Herrmann-Erlee, I. Koornneef, W. Kruijer and Y. M. Kramer

ABSTRACT

Although the structure of several members of the GH receptor family has been defined, signal transduction following GH binding to its receptor has not been elucidated. Mouse osteoblasts were used to study the effect of GH on immediate early gene expression and, subsequently, the cellular signal(s) mediating this expression were analysed. GH rapidly and transiently induced the expression of c-jun and jun B in concert with the already reported expression of c-fos. The GH-induced expression of c-fos was completely blocked by the protein kinase inhibitors staurosporine and H7, indicating that the action of GH is mediated by one or several protein kinases. We next analysed the identity of the putative protein kinases in more detail by using a more specific protein kinase inhibitor, namely the ether-lipid 1-O-alkyl-2-O-methylglycerol, understood to be an inhibitor of protein kinase C (PKC). Data obtained from these studies revealed that GH-induced expression of c-fos is mediated by PKC. In addition, we observed a profound increase in formation of the PKC activator diacyglycerol upon addition of GH, a natural activator of PKC.

In conclusion, upon binding of GH to mouse osteoblasts, the receptor-mediated cellular signal involves diacyglycerol formation and activation of PKC, leading to the induction of oncogene expression. Finally, the expression of c-fos, c-jun and jun B results in an increased binding of protein complexes to AP-1 binding sites.