cAMP-dependent protein kinase modulates expression and subcellular localization of Dolichos biflorus agglutinin binding sites in renal epithelial cells.
Previous studies demonstrated that, upon attaining confluence, a clone of the renal epithelial cell, LLC-PK1, expressed progressively binding sites for the lectin Dolichos biflorus agglutinin (DBA) at the apical cell surface. Activation of cAMP-dependent protein kinase enhanced surface expression dramatically. The goal of this study was to define the process leading to surface expression of DBA binding sites and to investigate further the role of cAMP-dependent protein kinase in modulating surface expression. Both subconfluent and confluent cells exhibited intracellular DBA binding sites (50-70% of total cellular binding sites) in a perinuclear vesicular compartment which was disrupted by Brefeldin A treatment. Both total cellular content and the proportion of DBA binding sites at the cell surface increased modestly after confluence was attained. A 48 h treatment of cells with 1-methyl-3-isobutyl xanthine, a phosphodiesterase inhibitor, dramatically increased the level of cellular DBA binding sites as well as the proportion of DBA binding sites at the cell surface. Analysis of two mutants of this cell line suggests that the effect of 1-methyl-3-isobutyl xanthine requires cAMP-dependent protein kinase activity but is not due to cAMP-dependent protein kinase-mediated activation of gene transcription.
Amsler
K
K
Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000116:Acetylgalactosamine / Q000378:metabolism; D000818:Animals; D020126:Brefeldin A; D002451:Cell Compartmentation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003260:Contact Inhibition; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D003517:Cyclopentanes / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D037102:Lectins / Q000378:metabolism*; D037121:Plant Lectins; D011975:Receptors, Mitogen / Q000378:metabolism*; D013552:Swine; D015854:Up-Regulation / Q000187:drug effects
D003517:Cyclopentanes; C027654:Dolichos biflorus lectin receptor; D006023:Glycoproteins; D037102:Lectins; D037121:Plant Lectins; D011975:Receptors, Mitogen; C036554:dolichos biflorus agglutinin; D020126:Brefeldin A; D017868:Cyclic AMP-Dependent Protein Kinases; D000116:Acetylgalactosamine; D015056:1-Methyl-3-isobutylxanthine