Phosphoinositide 3-kinase is activated by MUC1 but not responsible for MUC1-induced suppression of Toll-like receptor 5 signaling

Kosuke Kato, Wenju Lu, Hirofumi Kai, K. Chul Kim

Research output: Contribution to journalArticle

Abstract

MUC1 is a membrane-tethered mucin-like glycoprotein expressed on the surface of various mucosal epithelial cells as well as hematopoietic cells. Recently, we showed that MUC1 suppresses flagellin-induced Toll-like receptor (TLR) 5 signaling both in vivo and in vitro through cross talk with TLR5. In this study, we determined whether phosphoinositide 3-kinase (PI3K), a negative regulator of TLR5 signaling, is involved in the cross talk between MUC1 and TLR5 using various genetically modified epithelial cell lines. Our results showed 1) activation of MUC1 induced recruitment of the PI3K regulatory subunit p85 to the MUC1 cytoplasmic tail (CT) as well as Akt phosphorylation, 2) MUC1-induced Akt phosphorylation required the presence of Tyr20 within the PI3K binding motif of the MUC1 CT, and 3) mutation of Tyr20 or pharmacological inhibition of PI3K activation failed to block MUC1-induced suppression of TLR5 signaling. We conclude that whereas PI3K is downstream of MUC1 activation and negatively regulates TLR5 signaling, it is not responsible for MUC1-induced suppression of TLR5 signaling.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume293
Issue number3
DOIs
StatePublished - Sep 2007

Fingerprint

Toll-Like Receptor 5
1-Phosphatidylinositol 4-Kinase
Epithelial Cells
Phosphorylation
Flagellin
Mucins
Glycoproteins
Pharmacology
Cell Line
Mutation
Membranes

Keywords

  • Flagellin
  • Innate immunity
  • Mucin

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Cell Biology
  • Physiology

Cite this

Phosphoinositide 3-kinase is activated by MUC1 but not responsible for MUC1-induced suppression of Toll-like receptor 5 signaling. / Kato, Kosuke; Lu, Wenju; Kai, Hirofumi; Kim, K. Chul.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 293, No. 3, 09.2007.

Research output: Contribution to journalArticle

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