mkp-1 encoding mitogen-activated protein kinase phosphatase 1, a verotoxin 1 responsive gene, detected by differential display reverse transcription-PCR in Caco-2 cells

Shihoko Kojima, Itaru Yanagihara, Gengo Kono, Tomomi Sugahara, Hatsumi Nasu, Mika Kijima, Akiko Hattori, Toshio Kodama, Ken Ichi Nagayama, Takeshi Honda

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The major cytotoxic effect of the verotoxins (VTs) produced by strains of VT-producing Escherichia coli is the inhibition of host-cell protein synthesis, but VTs are also suspected to play a role in apoptotic cell signaling and cytokine release. Four differentially expressed genes, including mkp-1 (encoding mitogen-activated protein kinase phospatase 1), were detected by differential display reverse transcription-PCR (DD RT-PCR) stimulated by VT1 in Caco-2 cells. Northern blot analysis showed the induction of mkp-I mRNA 6 h after VT1 stimulation. Neither mutant VT1 (mutVT1), harboring two mutations in the A subunit (E167Q-R170L), nor cycloheximide induced mkp-1 mRNA, but mkp-1 mRNA was detected with both wild- type VT1 (wtVT1) and anisomycin, a 28S rRNA inhibitor. Therefore, we concluded that the A subunit of VT1 was essential for mkp-1 induction. Increased amounts of phosphorylated c-Jun protein were also found with wtVT1 and anisomycin. Although the precise mechanism of induction of MKP-1 is unknown, we hypothesized that 28S rRNA not only was a sensor for ribotoxic stress, but also was involved in the signal cascade of MKP-1. This is the first report of detection by DD RT-PCR of cellular genes induced by bacterial toxins.

Original languageEnglish (US)
Pages (from-to)2791-2796
Number of pages6
JournalInfection and immunity
Volume68
Issue number5
DOIs
StatePublished - May 2000

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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