The protein tyrosine phosphatase alpha modifies insulin secretion in INS-1E cells |
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Authors: | Kapp Katja Metzinger Elisabeth Kellerer Monika Häring Hans-Ulrich Lammers Reiner |
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Institution: | Medical Clinic IV, Otfried-Müller-Str. 10, 72076 Tuebingen, Germany. |
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Abstract: | Increasing evidence indicates a role of insulin signalling for insulin secretion from the pancreatic beta-cells. Therefore, regulators of insulin signalling, like protein tyrosine phosphatases, could also have an impact on insulin secretion. Here, we investigated a possible role of the negative regulator protein tyrosine phosphatase alpha (PTP alpha) for insulin secretion. RT-PCR analysis confirmed that both splice variants of the extracellular domain of PTP alpha that vary by an insert of 9 amino acids are expressed in human islets and insulinoma cells (INS-1E, RIN1046-38). Overexpression of the wild type PTP alpha splice variant containing the 9 amino acids reduced insulin secretion, as did a mutant form unable to bind Grb2 (Tyr798Phe). By contrast, overexpression of a phosphatase inactive mutant improved insulin secretion. These data reveal a functional relevance of PTP alpha for insulin secretion. |
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Keywords: | Insulin secretion Protein tyrosine phosphatase PTPα Splice variant |
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