Tyrosine phosphorylated Par3 regulates epithelial tight junction assembly promoted by EGFR signaling

Yiguo Wang, Dan Du, Longhou Fang, Guang Yang, Chenyi Zhang, Rong Zeng, Axel Ullrich, Friedrich Lottspeich, Zhengjun Chen

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


The conserved polarity complex, comprising the partitioning-defective (Par) proteins Par3 and Par6, and the atypical protein kinase C, functions in various cell-polarization events and asymmetric cell divisions. However, little is known about whether and how external stimuli-induced signals may regulate Par3 function in epithelial cell polarity. Here, we found that Par3 was tyrosine phosphorylated through phosphoproteomic profiling of pervanadate-induced phosphotyrosine proteins. We also demonstrated that the tyrosine phosphorylation event induced by multiple growth factors including epidermal growth factor (EGF) was dependent on activation of Src family kinase (SFK) members c-Src and c-Yes. The tyrosine residue 1127 (Y1127) of Par3 was identified as the major EGF-induced phosphorylation site. Moreover, we found that Y1127 phosphorylation reduced the association of Par3 with LIM kinase 2 (LIMK2), thus enabling LIMK2 to regulate cofilin phosphorylation dynamics. Substitution of Y1127 for phenylalanine impaired the EGF-induced Par3 and LIMK2 dissociation and delayed epithelial tight junction (TJ) assembly considerably. Collectively, these data suggest a novel, phosphotyrosine-dependent fine-tuning mechanism of Par3 in epithelial TJ assembly controlled by the EGF receptor-SFK signaling pathway.

Original languageEnglish (US)
Pages (from-to)5058-5070
Number of pages13
JournalEMBO Journal
Issue number21
StatePublished - Nov 1 2006


  • EGFR signaling
  • LIMK2
  • Par3
  • Phosphotyrosine
  • Tight junction

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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