Human Secretagogin ELISA Kit

Elucidating the regulation of glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells is important for understanding and treating diabetes. The pancreatic beta cell line, MIN6, retains GSIS but gradually loses it in long-term culture. The MIN6 subclone, MIN6c4, exhibits well-regulated GSIS even after prolonged culture. We previously used DNA microarray analysis to compare gene expression in the parental MIN6 cells and MIN6c4 cells and identified several differentially regulated genes that may be involved in maintaining GSIS. Here we investigated the potential roles of six of these genes in GSIS: Tmem59l (Transmembrane protein 59 like), Scgn (Secretagogin), Gucy2c (Guanylate cyclase 2c), Slc29a4 (Solute carrier family 29, member 4), Cdhr1 (Cadherin-related family member 1), and Celsr2 (Cadherin EGF LAG seven-pass G-type receptor 2). These genes were knocked down in MIN6c4 cells using lentivirus vectors expressing gene-specific short hairpin RNAs (shRNAs), and the effects of the knockdown on insulin expression and secretion were analyzed. Suppression of Tmem59l, Scgn, and Gucy2c expression resulted in significantly decreased glucose- and/ or KCl-stimulated insulin secretion from MIN6c4 cells, while the suppression of Slc29a4 expression resulted in increased insulin secretion. Tmem59l overexpression rescued the phenotype of the Tmem59l knockdown MIN6c4 cells, and immunostaining analysis indicated that the TMEM59L protein colocalized with insulin and GM130, a Golgi complex marker, in MIN6 cells. Collectively, our findings suggested that the proteins encoded by Tmem59l, Scgn, Gucy2c, and Slc29a4 play important roles in regulating GSIS. Detailed studies of these proteins and their functions are expected to provide new insights into the molecular mechanisms involved in insulin secretion.

Secretagogin (SCGN), a hexa EF-hand calcium-binding protein, is highly expressed in the endocrine cells (especially in pancreatic islets) and in restricted neuronal sub-populations, albeit at comparatively low level. Since SCGN is predicted to be a potential neuroendocrine marker in carcinoid tumors of lung and gastrointestinal tract, it is of paramount importance to understand the features of this protein in different environment for assigning its crucial functions in different tissues and under pathophysiological conditions. To score out the limitation of protein for in vitro studies, we report a one-step, high purity and high level bacterial purification of secretagogin by refolding from the inclusion bodies yielding about 40 mg protein per litre of bacterial culture. We also report previously undocumented Ca2+/Mg2+ binding and hydrodynamic properties of secretagogin. (c) 2015 Elsevier Inc. All rights reserved.