| Autor: |
Becker A; Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Building 46, D-66424 Homburg, Germany., Götz C; Medical Biochemistry and Molecular Biology, Saarland University, Building 44, D-66424 Homburg, Germany., Montenarh M; Medical Biochemistry and Molecular Biology, Saarland University, Building 44, D-66424 Homburg, Germany., Philipp SE; Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Building 46, D-66424 Homburg, Germany. |
| Abstrakt: |
In pancreatic β-cells of the line INS-1, glucose uptake and metabolism induce the openings of Ca 2+ -permeable TRPM3 channels that contribute to the elevation of the intracellular Ca 2+ concentration and the fusion of insulin granules with the plasma membrane. Conversely, glucose-induced Ca 2+ signals and insulin release are reduced by the activity of the serine/threonine kinase CK2. Therefore, we hypothesized that TRPM3 channels might be regulated by CK2 phosphorylation. We used recombinant TRPM3α2 proteins, native TRPM3 proteins from INS-1 β-cells, and TRPM3-derived oligopeptides to analyze and localize CK2-dependent phosphorylation of TRPM3 channels. The functional consequences of CK2 phosphorylation upon TRPM3-mediated Ca 2+ entry were investigated in Fura-2 Ca 2+ -imaging experiments. Recombinant TRPM3α2 channels expressed in HEK293 cells displayed enhanced Ca 2+ entry in the presence of the CK2 inhibitor CX-4945 and their activity was strongly reduced after CK2 overexpression. TRPM3α2 channels were phosphorylated by CK2 in vitro at serine residue 1172. Accordingly, a TRPM3α2 S 1172 A mutant displayed enhanced Ca 2+ entry. The TRPM3-mediated Ca 2+ entry in INS-1 β-cells was also strongly increased in the presence of CX-4945 and reduced after overexpression of CK2. Our study shows that CK2-mediated phosphorylation controls TRPM3 channel activity in INS-1 β-cells. |
