Tight-junction protein ZO-1 isoforms (α+ and α−) show differential extractability and epidermal-growth-factor-induced tyrosine phosphorylation in A431 cells

PROTOPLASMA ◽  
1999 ◽  
Vol 206 (4) ◽  
pp. 211-218 ◽  
Author(s):  
C. M. Van Itallie ◽  
J. M. Anderson
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tight Junction ◽  
Tyrosine Phosphorylation ◽  
Tight Junction Protein ◽  
A431 Cells ◽  
Junction Protein ◽  
Epidermal Growth

Epidermal growth factor induces tyrosine phosphorylation and reorganization of the tight junction protein ZO-1 in A431 cells

1995 ◽  
Vol 108 (4) ◽  
pp. 1735-1742 ◽  
Author(s):  
C.M. Van Itallie ◽  
M.S. Balda ◽  
J.M. Anderson
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tight Junction ◽  
Tyrosine Phosphorylation ◽  
Intercellular Junctions ◽  
Cytochalasin D ◽  
Tight Junction Protein ◽  
A431 Cells ◽  
Junction Protein ◽  
Epidermal Growth

Addition of epidermal growth factor (EGF) to A431 human epidermal carcinoma cells results in actin reorganization and phosphorylation of several cytoskeletal proteins. In the present study, we found that EGF treatment of this cell line also results in the redistribution and tyrosine phosphorylation of ZO-1. In normal polarized epithelial cells, ZO-1 is restricted to the cytoplasmic surface of the most apical of the intercellular junctions, the tight junction. In contrast, ZO-1 in the majority of unstimulated A431 cells in small subconfluent islands colocalizes with actin along the lateral cell membranes and in rare microspikes and membrane ruffles. Exposure to EGF results in a transient redistribution of actin into an apically positioned ring. ZO-1 becomes highly focused at apical sites of cell contact and co-localizes with the newly formed band of perijunctional actin. Coincidently, ZO-1 and another tight junction protein, ZO-2, become transiently phosphorylated on tyrosine residues, as determined by anti-phosphotyrosine immunoblotting. Pre-treatment of A431 cells with cytochalasin D, which disrupts normal microfilament organization, does not affect EGF-dependent phosphorylation of the EGF receptor. However, cytochalasin D pretreatment blocks both the EGF-induced ZO-1 rearrangement and tyrosine phosphorylation, suggesting that these responses are dependent on an intact actin microfilament system. We speculate that the transient tyrosine phosphorylation of ZO-1 in response to EGF treatment may be involved in remodeling of intercellular junctions in A431 cells.

scholarly journals Abnormal Epithelial Cell Polarity and Ectopic Epidermal Growth Factor Receptor (EGFR) Expression Induced in Emx2 KO Embryonic Gonads

Endocrinology ◽  
2010 ◽  
Vol 151 (12) ◽  
pp. 5893-5904 ◽  
Author(s):  
Masatomo Kusaka ◽  
Yuko Katoh-Fukui ◽  
Hidesato Ogawa ◽  
Kanako Miyabayashi ◽  
Takashi Baba ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Epithelial Cells ◽  
Tight Junction ◽  
Tyrosine Phosphorylation ◽  
Growth Factor Receptor ◽  
Egfr Expression ◽  
Epidermal Growth ◽  
Viral Oncogene Homolog

The gonadal primordium first emerges as a thickening of the embryonic coelomic epithelium, which has been thought to migrate mediodorsally to form the primitive gonad. However, the early gonadal development remains poorly understood. Mice lacking the paired-like homeobox gene Emx2 display gonadal dysgenesis. Interestingly, the knockout (KO) embryonic gonads develop an unusual surface accompanied by aberrant tight junction assembly. Morphological and in vitro cell fate mapping studies showed an apparent decrease in the number of the gonadal epithelial cells migrated to mesenchymal compartment in the KO, suggesting that polarized cell division and subsequent cell migration are affected. Microarray analyses of the epithelial cells revealed significant up-regulation of Egfr in the KO, indicating that Emx2 suppresses Egfr gene expression. This genetic correlation between the two genes was reproduced with cultured M15 cells derived from mesonephric epithelial cells. Epidermal growth factor receptor signaling was recently shown to regulate tight junction assembly through sarcoma viral oncogene homolog tyrosine phosphorylation. We show through Emx2 KO analyses that sarcoma viral oncogene homolog tyrosine phosphorylation, epidermal growth factor receptor tyrosine phosphorylation, and Egfr expression are up-regulated in the embryonic gonad. Our results strongly suggest that Emx2 is required for regulation of tight junction assembly and allowing migration of the gonadal epithelia to the mesenchyme, which are possibly mediated by suppression of Egfr expression.

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