Key role of PKC and Ca2+ in EGF protection of microtubules and intestinal barrier against oxidants

被引:47
作者
Banan, A
Fields, JZ
Zhang, Y
Keshavarzian, A
机构
[1] Rush Univ, Med Ctr, Dept Internal Med, Div Digest Dis, Chicago, IL 60612 USA
[2] Rush Univ, Med Ctr, Dept Pharmacol, Chicago, IL 60612 USA
[3] Rush Univ, Med Ctr, Dept Mol Biophys & Physiol, Chicago, IL 60612 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY | 2001年 / 280卷 / 05期
关键词
tubulin; growth factor; monolayer barrier permeability; Caco-2; cells;
D O I
10.1152/ajpgi.2001.280.5.G828
中图分类号
R57 [消化系及腹部疾病];
学科分类号
摘要
Using monolayers of human intestinal (Caco-2) cells, we showed that growth factors (GFs) protect microtubules and barrier integrity against oxidative injury. Studies in nongastrointestinal cell models suggest that protein kinase C (PKC) signaling is key in GF-induced effects and that cytosolic calcium concentration ([ Ca2+](i)) is essential in cell integrity. We hypothesized that GF protection involves activating PKC and maintaining normal [Ca2+](i). Monolayers were pretreated with epidermal growth factor (EGF) or PKC or Ca2+ modulators before exposure to oxidants (H2O2 or HOCl). Oxidants disrupted microtubules and barrier integrity, and EGF protected from this damage. EGF caused rapid distribution of PKC-alpha, PKC- betaI, and PKC-zeta isoforms to cell membranes, enhancing PKC activity of membrane fractions while reducing PKC activity of cytosolic fractions. EGF enhanced Ca-45(2+) efflux and prevented oxidant-induced (sustained) rises in [Ca2+](i). PKC inhibitors abolished and PKC activators mimicked EGF protection. Oxidant damage was mimicked by and potentiated by a Ca2+ ionophore (A-23187), exacerbated by high-Ca2+ media, and prevented by calcium removal or chelation or by Ca2+ channel antagonists. PKC activators mimicked EGF on both Ca-45(2+) efflux and [Ca2+](i). Membrane Ca2+-ATPase pump inhibitors prevented protection by EGF or PKC activators. In conclusion, EGF protection of microtubules and the intestinal epithelial barrier requires activation of PKC signal transduction and normalization of [Ca2+](i).
引用
收藏
页码:G828 / G843
页数:16
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