Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: Role of protein kinase C

Ya Qin Zhu, Yu Lu, Xiaodi Tan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Intestinal epithelial cells are constantly stimulated by reactive oxidant metabolites (ROMs) in inflamed mucosa. Monochloramine (NH 2 Cl), a cell-permeant ROM, is particularly relevant to the pathogenesis of inflammation in the gastrointestinal tract. Nuclear speckles, a unique nuclear subcompartment, accumulate a family of proteins, namely, serine- and arginine-rich (SR) proteins. They play important roles in regulation of pre-mRNA splicing. Currently, little is known about the link between inflammatory stimulation and the pre-mRNA splicing process, although gene expression is changed in inflamed tissues. The present study was designed to investigate whether stimulation of human colonic epithelial cells (HT-29 and Caco-2 cell lines) with NH 2 Cl affects nuclear speckles and their components. By indirect immunofluorescence, nuclear speckles have been shown to undergo rapid aggregation after NH 2 Cl stimulation. By utilizing Western blotting, SRp30 (a subset of SR proteins) in intestinal epithelial cells was found to be phosphorylated after NH 2 Cl treatment, whereas other SR proteins were not responsive to NH 2 Cl stimulation. The cytotoxic effect of NH 2 Cl was excluded by both negative lactate dehydrogenase assay and propidium iodide staining. Therefore, NH 2 Cl-induced morphological changes on nuclear speckles and phosphorylated SRp30 do not result from intestinal epithelial injury. Furthermore, the effect of NH 2 Cl on nuclear speckles and SRp30 was blocked by bisindolylmaleimide I, a selective PKC inhibitor. Together, the available data suggest that stimulation of intestinal epithelial cells with NH 2 Cl results in a consequent change on pre-mRNA splicing machinery via a distinctive signal pathway involving activation of PKC. This effect may contribute to oxidant-induced pathophysiological changes in the gastrointestinal tract.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume285
Issue number5 54-5
StatePublished - Nov 1 2003

Keywords

  • Intestinal epithelial cell
  • Pre-mRNA splicing machinery
  • Reactive oxygen metabolites
  • SR proteins
  • Signal transduction

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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