Characterization of the rat homologue of the human neuroendocrine marker secretagogin new functional implications by in vitro studies
Wolfgang Gartner1, Greisa Vila4, Teodora Daneva2, Felic Koc-Saral1, Otto Majdic3, Anastasia Nabokih1, Anton Luger4 & Ludwig Wagner1
Objective: Establishment of rodent in vitro cell systems for the extension of the functional data about the recently cloned neuroendocrine marker secretagogin.
Methods: 1. DNA-cloning; 2. Antibody generation; 3. Immunoblotting and Immunohistochemistry; 4. Cell-transfection; 5. Luciferase Reporter Assays; 6. ELISA.
Results: 1. We characterized the rat homologue of human secretagogin (rat secretagogin) and demonstrated the homologous tissue expression pattern of both proteins. 2. Highest rat secretagogin expression levels were found in rat pancreatic islets and in the rat insulinoma cell lines Rin-5F and INS-1. 3. There exists a considerable degree of sequence homology between human and rat secretagogin, indicating comparable functional properties. 4. Overexpression of rat secretagogin in Rin-5F and in INS-1 cells induced an increase in insulin secretion and expression, which is mediated mainly via the promoter elements AP-1 and CRE. 5. Insulin and rat secretagogin are secreted in an inverse ratio by Rin-5F and INS-1 cells upon incubation with dexamethasone and other agents known for influencing the insulin secretion.
Conclusion: We characterized the rat homologue of human secretagogin and present an in vitro system for its functional analysis, which emphasize its regulative involvement in insulin secretion and expression.