A cyclic AMP protein kinase A‐dependent mechanism by which rotavirus impairs the expression and enzyme activity of brush border‐associated sucrase‐isomaltase in differentiated intestinal Caco‐2 cells

• Published in: Cellular microbiology Vol. 6; no. 8; pp. 719 - 731
• Main Authors: Martin‐Latil, Sandra, Cotte‐Laffitte, Jacqueline, Beau, Isabelle, Quéro, Anne‐Marie, Géniteau‐Legendre, Monique, Servin, Alain L.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.08.2004
• Subjects: Caco-2 Cells - drug effects; Caco-2 Cells - metabolism; Caco-2 Cells - virology; Calcium Channel Blockers - pharmacology; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Cyclic AMP-Dependent Protein Kinases - metabolism; Depsipeptides; Human rotavirus; Humans; Keratins - metabolism; Peptides, Cyclic - pharmacology; Phosphorylation; Rotavirus - physiology; Signal Transduction; Sucrase-Isomaltase Complex - antagonists & inhibitors; Sucrase-Isomaltase Complex - biosynthesis; Sucrase-Isomaltase Complex - metabolism
• ISSN: 1462-5814; 1462-5822
• DOI: 10.1111/j.1462-5822.2004.00396.x

Summary We undertook a study of the mechanism by which rhesus monkey rotavirus (RRV) impairs the expression and enzyme activity of brush border‐associated sucrase isomaltase (SI) in cultured, human, fully differentiated, intestinal Caco‐2 cells. We provide evidence that the RRV‐induced defects in the expression and enzyme activity of SI are not related to the previously observed, RRV‐induced, Ca2+‐dependent, disassembly of the F‐actin cytoskeleton. This conclusion is based on the facts that: (i) the intracellular Ca2+ blocker, BAPTA/AM, which antagonizes the RRV‐induced increase in [Ca2+]i, fails to inhibit the RRV‐induced decrease in SI expression and enzyme activity; and (ii) Jasplakinolide (JAS) treatment, known to stabilize actin filaments, had no effect on the RRV‐induced decrease in SI expression. Results reported here demonstrate that the RRV‐induced impairment in the expression and enzyme activity of brush border‐associated SI results from a hitherto unknown mechanism involving PKA signalling. This conclusion is based on the observations that (i) intracellular cAMP was increased in RRV‐infected cells and (ii) treatment of RRV‐infected cells with PKA blockers resulted in the reappearance of apical SI expression, accompanied by the restoration of the enzyme activity at the brush border. In addition, in RRV‐infected cells a twofold increase of phosphorylated form of cytokeratin 18 was observed after immunopurification and Western Blot analysis, which was antagonized by exposing the RRV‐infected cells to the PKA blockers.