Stimulation by insulin of a serine kinase in human platelets that phosphorylates and activates the cGMP-inhibited cAMP phosphodiesterase

Summary, in English

We previously reported that insulin stimulation of human platelets induces serine phosphorylation and activation of the cGMP-inhibited cAMP phosphodiesterase (cGI-PDE). Here, we describe methods to detect and partially purify an insulin-stimulated cGI-PDE kinase (cGI-PDE ISK) from lysates of platelets incubated with insulin. Incubation of human platelets with 10(-8) M insulin increased cGI-PDE ISK activity two-fold. The DEAE-Sephacel-purified cGI-PDE ISK phosphorylated the cGI-PDE on serine in a time- and concentration-dependent manner resulting in an increased incorporation of about 0.2 mol of [32P]/mol of cGI-PDE and 15-20% increase in cGI-PDE activity. The phosphorylation of cGI-PDE was not affected by 10 microM PKI, 1 microgram/ml of heparin, 3 mM CaCl2 or 1 mM MnCl2. cGI-PDE ISK did not adsorb to antiphosphotyrosine antibodies. To maintain its activation it was necessary to add protein phosphatase inhibitors to the lysate-buffers. All of these findings are consistent with the conclusion that a serine/threonine phosphorylation of the cGI-PDE ISK is involved in its activation by insulin.

• Author: Pilar Lopez-Aparicio; Per Belfrage; Vincent C Manganiello; Tetsuro Kono; Eva Degerman
• Department/s: Insulin Signal Transduction
• Publishing year: 1993
• Language: English
• Pages: 1137-1144
• Publication/Series: Biochemical and Biophysical Research Communications
• Volume: 193
• Issue: 3
• Links: http://dx.doi.org/10.1006/bbrc.1993.1744
• Document type: Journal article
• Publisher: Elsevier
• Topic: Biological Sciences
• Status: Published
• Research group: Insulin Signal Transduction
• ISBN/ISSN/Other: ISSN: 1090-2104