TY - JOUR T1 - The β1 Isoform of Protein Kinase C Mediates the Protective Effects of Epidermal Growth Factor on the Dynamic Assembly of F-Actin Cytoskeleton and Normalization of Calcium Homeostasis in Human Colonic Cells JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 852 LP - 866 DO - 10.1124/jpet.301.3.852 VL - 301 IS - 3 AU - A. Banan AU - J. Z. Fields AU - A. Farhadi AU - D. A. Talmage AU - L. Zhang AU - A. Keshavarzian Y1 - 2002/06/01 UR - http://jpet.aspetjournals.org/content/301/3/852.abstract N2 - Using intestinal monolayers, we showed that F-actin cytoskeletal stabilization and Ca2+ normalization contribute to epidermal growth factor (EGF)-mediated protection against oxidant injury. However, the intracellular mediator responsible for these protective effects remains unknown. Since the protein kinase C-β1 (PKC-β1) isoform is abundant in our naive (N) cells, we hypothesized that PKC-β1 is essential to EGF protection. Monolayers of N Caco-2 cells were exposed to H2O2 ± EGF, PKC, or Ca2+ modulators. Other cells were transfected to over-express PKC-β1 or to inhibit its expression and then pretreated with low or high doses of EGF or a PKC activator, OAG (1-oleoyl-2-acetyl-sn-glycerol), before H2O2. In N monolayers exposed to oxidant, pretreatment with EGF or PKC activators activated PKC-β1, enhanced 45Ca2+efflux, normalized Ca2+, decreased monomeric G-actin, increased stable F-actin, and protected the cytoarchitecture of the actin. PKC inhibitors prevented these protective effects. Transfected cells stably over-expressing PKC-β1 (+3.1-fold) but not N cell monolayers were protected from injury by even lower doses of EGF or OAG. EGF or OAG rapidly activated the over-expressed PKC-β1. Antisense inhibition of PKC-β1 expression (−90%) prevented all measures of EGF protection. Inhibitors of Ca2+-ATPase prevented EGF protection in N cells as well as protective synergism in transfected cells. EGF protects the assembly of the F-actin cytoskeleton in intestinal monolayers against oxidants in large part through the activation of PKC-β1. EGF normalizes Ca2+ by enhancing Ca2+ efflux through PKC-β1. We have identified novel biologic functions, protection of actin and Ca2+homeostasis, among the classical isoforms of PKC. The American Society for Pharmacology and Experimental Therapeutics ER -