PKA inhibitor, H-89, affects the intracellular transit of regulated secretory proteins in rat lacrimal glands

• Published in: American Journal of Physiology: Cell Physiology Vol. 274; no. 1; pp. C262 - C271
• Main Authors: Robin, P, Rossignol, B, Raymond, M. N
• Format: Journal Article
• Language: English
• Published: United States 01.01.1998
• Subjects: Animals; Calcimycin - pharmacology; Calcium - metabolism; Carbachol - pharmacology; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Enzyme Inhibitors - pharmacology; Exocytosis; Galactose - metabolism; Glycoproteins - biosynthesis; Glycoproteins - metabolism; Golgi Apparatus - physiology; In Vitro Techniques; Isoquinolines - pharmacology; Kinetics; Lacrimal Apparatus - drug effects; Lacrimal Apparatus - physiology; Leucine - metabolism; Male; Rats; Rats, Sprague-Dawley; Sulfonamides; Temperature
• ISSN: 0363-6143; 0002-9513; 1522-1563
• DOI: 10.1152/ajpcell.1998.274.1.c262

Laboratoire de Biochimie des Transports Cellulaires, Centre National de la Recherche Scientifique, ERS 0571, Université Paris XI, 91 405 Orsay Cedex, France We tested the effect of H-89, a protein kinase A (PKA) inhibitor, on the intracellular transit of the regulated secretory proteins in rat lacrimal glands. We show that H-89, by itself, induces the secretion of newly synthesized proteins trafficking in its presence but not of proteins already stored in the mature secretory granules. This secretion does not depend on the presence of extracellular Ca 2+ . The proteins released are identical to those secreted after cholinergic stimulation or under the action of the ionophore A-23187, but the secretion level is ~40% lower. The effect of H-89 seems to be due to PKA inhibition because other protein kinase inhibitors (calphostin C, chelerythrine, H-85) do not induce secretion. We further show that H-89 does not modify the rate of glycoprotein galactosylation but induces the secretion of newly galactosylated glycoproteins. Finally, we used a "20°C block" procedure to show that H-89 affects a trans -Golgi network (TGN) or post-TGN step of the secretory pathway. Our results demonstrate that, in lacrimal cells, H-89 affects the intracellular trafficking of secretory proteins, suggesting a role for PKA in this process. protein kinase A; regulation of intracellular transit; protein sorting; protein secretion