Project description:(original Title) Phenothiazine Neuroleptics Signal To The Human Insulin Promoter As Revealed By A Novel Human b-Cell Line Based High-Throughput Screen. To address the current deficiency in human beta-cell models, we have developed a cell line from human islets in which the expression of insulin and other beta-cell restricted genes are modulated by an inducible form of the bHLH transcription factor E47. In an effort to probe the global pattern of gene expression in T6PNE in an unbiased fashion, oligonucleotide microarray analysis was performed on T6PNE in the presence and absence of E47 induction and compared against human islets. Our analysis reveals that T6PNE express a substantial percentage of the b-cell specific geneset, and that this is further enhanced by the induction of E47. This cell line, T6PNE, was then screened against a library of known drugs for those that increase insulin promoter activity. Interestingly, members of the phenothiazine class of neuroleptics increased insulin gene expression upon short term exposure. Chronic treatment, however, resulted in suppression of insulin promoter activity, consistent with the effect of phenothiazines observed clinically to induce diabetes in chronically treated patients. In addition to providing insights into previously unrecognized targets and mechanisms of action of phenothiazines, the novel cell line described here provides a broadly applicable platform for mining new molecular drug targets and central regulators of beta-cell differentiated function. Gene expression studies in: Three human islet samples; Five T6PNE samples; Seven T6PNE induced with E47.
Project description:(original Title) Phenothiazine Neuroleptics Signal To The Human Insulin Promoter As Revealed By A Novel Human b-Cell Line Based High-Throughput Screen. To address the current deficiency in human beta-cell models, we have developed a cell line from human islets in which the expression of insulin and other beta-cell restricted genes are modulated by an inducible form of the bHLH transcription factor E47. In an effort to probe the global pattern of gene expression in T6PNE in an unbiased fashion, oligonucleotide microarray analysis was performed on T6PNE in the presence and absence of E47 induction and compared against human islets. Our analysis reveals that T6PNE express a substantial percentage of the b-cell specific geneset, and that this is further enhanced by the induction of E47. This cell line, T6PNE, was then screened against a library of known drugs for those that increase insulin promoter activity. Interestingly, members of the phenothiazine class of neuroleptics increased insulin gene expression upon short term exposure. Chronic treatment, however, resulted in suppression of insulin promoter activity, consistent with the effect of phenothiazines observed clinically to induce diabetes in chronically treated patients. In addition to providing insights into previously unrecognized targets and mechanisms of action of phenothiazines, the novel cell line described here provides a broadly applicable platform for mining new molecular drug targets and central regulators of beta-cell differentiated function.
Project description:This model is from the article:
Mass and information feedbacks through receptor endocytosis govern insulin signaling as revealed using a parameter-free modeling framework.
Brannmark C, Palmer R, Glad ST, Cedersund G, Stralfors P.
J Biol Chem.2010 Jun 25;285(26):20171-9.
20421297,
Abstract:
Insulin and other hormones control target cells through a network of signal-mediating molecules. Such networks are extremely complex due to multiple feedback loops in combination with redundancy, shared signal mediators, and cross-talk between signal pathways. We present a novel framework that integrates experimental work and mathematical modeling to quantitatively characterize the role and relation between co-existing submechanisms in complex signaling networks. The approach is independent of knowing or uniquely estimating model parameters because it only relies on (i) rejections and (ii) core predictions (uniquely identified properties in unidentifiable models). The power of our approach is demonstrated through numerous iterations between experiments, model-based data analyses, and theoretical predictions to characterize the relative role of co-existing feedbacks governing insulin signaling. We examined phosphorylation of the insulin receptor and insulin receptor substrate-1 and endocytosis of the receptor in response to various different experimental perturbations in primary human adipocytes. The analysis revealed that receptor endocytosis is necessary for two identified feedback mechanisms involving mass and information transfer, respectively. Experimental findings indicate that interfering with the feedback may substantially increase overall signaling strength, suggesting novel therapeutic targets for insulin resistance and type 2 diabetes. Because the central observations are present in other signaling networks, our results may indicate a general mechanism in hormonal control.