Evidence for the involvement of cAMP-GEF (Epac) pathway in amylase release from the rat parotid gland.
Amylase release from the rat parotid gland is mainly mediated in a cAMP-dependent protein kinase (PKA)-dependent manner. In the present study, amylase release mediated in cAMP-dependent and PKA-independent manners was investigated with a cAMP-regulated guanine nucleotide exchange factor (cAMP-GEF: Epac)-selective cAMP analogue, 8CPT-2Me-cAMP. The Epac was localized in the intracellular and the plasma membrane fractions. PKA activation by 8CPT-2Me-cAMP was 100-fold lower than that by cAMP. The amylase release (% of the total) from the intact parotid acinar cells was 16 and 3.6% by isoproterenol (1microM) and 8CPT-2Me-cAMP (200microM), respectively, and that from the saponin-permeabilized cells was 15 and 3% by cAMP (100microM) and 8CTP-2Me-cAMP (10microM), respectively. H-89 inhibited cAMP-induced amylase release, but did not inhibit 8CPT-2Me-cAMP-induced amylase release. These results indicated that amylase release by beta-adrenergic stimulation is mediated through both the cAMP/PKA and cAMP/Epac signal pathways.
Department of Biochemistry, School of Dentistry at Niigata, The Nippon Dental University, 1-8 Hamaura-cho, Niigata 951-8580, Japan. hshimo@ngt.ndu.ac.jp <hshimo@ngt.ndu.ac.jp>
Hiromi
H
Shimomura
Akane
A
Imai
Tomoko
T
Nashida
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D010306:Parotid Gland / Q000201:enzymology* / Q000378:metabolism; D051381:Rats
C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000681:Amylases