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- Fuxe, K, et al.
(author)
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The changing world of G protein-coupled receptors
- 2010
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In: Journal of receptor and signal transduction research. - : Informa UK Limited. - 1532-4281 .- 1079-9893. ; 30:5, s. 271-271
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Journal article (other academic/artistic)
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- Granas, Charlotta, et al.
(author)
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Mutagenesis of the human 5-HT1B receptor : Differences from the closely related 5-HT1A receptor and the role of residue F331 in signal transduction
- 1998
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In: Journal of Receptor and Signal Transduction Research. - : MARCEL DEKKER INC. - 1079-9893 .- 1532-4281. ; 18:4-6, s. 225-241
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Journal article (peer-reviewed)abstract
- We have used a combination of sequence comparisons, computer-based modeling and site-directed mutagenesis to investigate the molecular interactions involved in ligand binding and signal transduction of the human 5-HT1B receptor. Two amino acid residues, S212 in transmembrane region (TM) V and F331 in TM VI, were replaced by alanines. These amino acids are conserved in many G protein-coupled receptors and therefore likely to be important for receptor function. The mutant receptors were expressed in Chinese hamster ovary cells. The 5-HT-like agonist 5-carboxamidotryptamine (5-CT) bound with 15-fold lower affinity to the S212A mutant as compared to wild-type receptor and the antagonist methiothepin bound with 17-fold lower affinity to the F331A mutant. No reduction in the affinity of 5-HT was seen for the S212A mutant, although an equivalent mutation in the 5-HT1A receptor resulted in a 100-fold reduction of 5-HT binding. The inhibition of forskolin-stimulated cyclic AMP production by 5-HT was significantly reduced in cells expressing the F331A mutant, even though the endogenous ligand 5-HT bound with somewhat increased affinity. Methiothepin acted as an inverse agonist and increased the forskolin-stimulated cyclic AMP production at both the wild-type receptor and the mutants, and the effect was stronger on the F331A mutant. These results suggest that F331 is involved in the conformational changes necessary for signal transduction.
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- Hussain, Showket, et al.
(author)
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Methylation-mediated gene silencing of suppressor of cytokine signaling-1 (SOCS-1) gene in esophageal squamous cell carcinoma patients of Kashmir valley
- 2011
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In: Journal of Receptor and Signal Transduction Research. - : Informa Healthcare. - 1079-9893 .- 1532-4281. ; 31:2, s. 147-56
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Journal article (peer-reviewed)abstract
- CONTEXT: Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related deaths in Jammu and Kashmir. The negative regulation of tumor suppressor gene leading to change in signaling pathway is one of the major mechanisms responsible for tumorigenic transformation.OBJECTIVE: In the present study, the role of silencing of suppressor of cytokine signaling-1 (SOCS-1) gene, a negative regulator of JAK/STAT pathway, was analyzed in ESCC.METHODS: The expression pattern of SOCS-1 gene was analyzed in esophageal tumor biopsies although normal adjacent tissues that served as controls. Reverse transcriptase polymerase chain reaction (RT-PCR), immunohistochemistry, methylation-specific PCR (MSP), and human papillomavirus (HPV) detection were performed to assess the expression pattern and promoter methylation of SOCS-1 gene including HPV status in a total of 75 surgically resected tissue specimens.RESULTS: Compared with the level of SOCS-1 expression in normal tissues, 53% (40/75) of the tumor tissues expressed either undetectable or reduced SOCS-1 expression (>50% loss of expression), which was significantly associated with advanced clinical stage or severe histopathological grade of the disease (P < 0.01). Aberrant promoter methylation of the SOCS-1 gene was found in 45% (34/75) of the esophageal tumor tissues, which was also found to be significantly associated with advanced stage of esophageal carcinoma (P < 0.01). The prevalence of HPV infection was found in 19% of tumor cases, whereas no HPV could be detected in any of the normal adjacent tissues.CONCLUSION: Transcriptional inactivation of SOCS-1 gene, primarily due to its promoter hypermethylation although HPV infection, may play an important role in esophageal carcinogenesis in Kashmir.
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