The effect of ROCK on TNF-α-induced CXCL8 secretion by intestinal epithelial cell lines is mediated through MKK4 and JNK signaling

Cell Immunol. 2015 Feb;293(2):80-6. doi: 10.1016/j.cellimm.2014.12.011. Epub 2015 Jan 7.

Abstract

Intestinal epithelial cells (IEC) play a role in mucosal inflammatory responses by producing important chemokines like CXCL8 when stimulated by TNF-α. Previously, we found that IEC cell lines required the Rho-associated kinase, ROCK, for CXCL8 responses after IL-1 stimulation. This study extends these findings by showing that inhibiting ROCK suppressed TNF-α-induced CXCL8 secretion by Caco-2 and DLD1 colonic epithelial cell lines and CXCL8 mRNA levels in Caco-2 cells. RNAi knockdown experiments indicated that the inhibitory effect was mediated by ROCK2, and not ROCK1. Inhibiting ROCK had no effect on TNF-stimulated IκBα phosphorylation and degradation or p38 MAPK phosphorylation indicating that ROCK plays no role in these signaling pathways. However, inhibiting ROCK suppressed TNF-induced phosphorylation of the p54 JNK isoform and phosphorylation of the upstream MKK4 kinase. These results suggest that ROCK is required for CXCL8 responses by TNF-stimulated IEC by affecting intracellular signaling through MKK4 and JNK.

Keywords: CXCL8; Intestinal epithelial; JNK; MKK4; ROCK; TNF.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / pharmacology
  • Blotting, Western
  • Caco-2 Cells
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells / immunology
  • Humans
  • Inflammation / immunology*
  • Interleukin-8 / genetics
  • Interleukin-8 / immunology*
  • Interleukin-8 / metabolism
  • Intestines / cytology
  • Intestines / immunology*
  • JNK Mitogen-Activated Protein Kinases / immunology*
  • MAP Kinase Kinase 4 / immunology
  • Phosphorylation / immunology
  • Pyridines / pharmacology
  • RNA Interference / immunology
  • RNA, Messenger / chemistry
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Signal Transduction / immunology*
  • Tumor Necrosis Factor-alpha / immunology*
  • rho-Associated Kinases / antagonists & inhibitors
  • rho-Associated Kinases / immunology*

Substances

  • Amides
  • Enzyme Inhibitors
  • Interleukin-8
  • Pyridines
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha
  • Y 27632
  • rho-Associated Kinases
  • JNK Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4