| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Amylase release from parotid acinar cells is a typical model of cAMPmediated exocytosis. The role of Protein kinase A (PKA), however, has yet to phosphorylation wityout decreasing amylase release. Firstiy, we evaluated the effect of H89, a new PKA inhibitor, which is more lipophilic and 25 times more potent than H8, H89 strongly inhibited both amylase release and protein phosphorylation in a dose-dependent manner. Next, we have undertaken the direct introduction of PKA catalytic subunit into the parotid acini that were permeabilized by streptolysin-O (SLO). In the presence of 100 hemolytic units/ml SLO, cAMP increased amylase release in a time- and dose-dependent manner, PKI(5-24)peptide, a specific PKA inhibitor, makedly inhibited amylase release, but the extent of inhibition was approximately 50%. On the other hand, the PKA catalytic subnit obtained from Sigma induced amylase release. The release, however was mostly insensitive to the PKIand even to the heat-inactivation of the PKA catalytic subunit. Since the subunit preparation did not disturb amylase assay inself, substances added for stabilization of the subnit might have some effects on the secretory granule membrane or other cellular components of parotid acini.
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