The role of phosphoinositides, protein kinase C and protein kinase A in the K+ regulatory
signal transduction in human adrenocortical cells
The messenger mechanisms mediating K+ regulatory signals in human adrenocorticocytes were studied. It was shown that potassium ions initiated decay of polyphosphoinositides to inositolphosphates and obviously diacylglycerol. The latter compounds activate protein kinase C as affected by different agonists. Using western blotting method we showed translocation of PKC? from cytosol to membranes after adrenal tissue preincubation in the medium with increased K+ content (8.5 mM). Translocation means activation of the enzyme. Activity of PKC increased in the microsomal fraction and did not change in cytosol. Increased concentration of K+ in the incubation medium also activates protein kinase A, although to a lesser extent compared to PKC. Unlike PKC activity of PKA was changed in cytosol as well.
The possibility of involvement of several messenger systems in К+ signal transduction in human adrenocortical cells as well as the hypothesis on crosstalk between messenger mechanisms for main physiological agonists controlling aldosterone biosynthesis in the adrenals are discussed.
Published at the site: 2005-02-02
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