title: Tyrosine phosphorylated Par3 regulates epithelial tight junction assembly promoted by EGFR signaling.
abstract: 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.
authors.affiliation: Key Laboratory of Proteomics and Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yiguo
authors.initials: Y
authors.lastname: Wang
authors.forename: Dan
authors.initials: D
authors.lastname: Du
authors.forename: Longhou
authors.initials: L
authors.lastname: Fang
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.forename: Chenyi
authors.initials: C
authors.lastname: Zhang
authors.forename: Rong
authors.initials: R
authors.lastname: Zeng
authors.forename: Axel
authors.initials: A
authors.lastname: Ullrich
authors.forename: Friedrich
authors.initials: F
authors.lastname: Lottspeich
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Chen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity / Q000502:physiology; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D040901:Proteomics / Q000379:methods; D015398:Signal Transduction / Q000502:physiology*; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D008565:Membrane Proteins; C509689:PARD3 protein, human; C499657:PARD6A protein, human; D014443:Tyrosine; D011494:Protein Kinases; D066246:ErbB Receptors