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Lavinia Taliana, Miriam Benezra, Roseanne S. Greenberg, Sandra K. Masur, Audrey M. Bernstein; ZO-1: Lamellipodial Localization in a Corneal Fibroblast Wound Model. Invest. Ophthalmol. Vis. Sci. 2005;46(1):96-103. doi: https://doi.org/10.1167/iovs.04-0145.
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purpose. To explore the roles of ZO-1 in corneal fibroblasts and myofibroblasts in a model of wounding.
methods. Antibodies were used to identify ZO-1 in cultured rabbit corneal fibroblasts by immunocytochemistry, Western blot analysis, and immunoprecipitation. For colocalization studies, antibodies to β-catenin, cadherins, connexins, integrins, α-actinin, and cortactin were used. G- and F-actin were identified by DNase and rhodamine phalloidin, respectively. To study ZO-1 localization during cell migration, confluent corneal fibroblasts were subjected to scrape-wounding and evaluated by immunocytochemistry.
results. As predicted from previous studies, ZO-1 colocalized with cadherins and connexin 43 in intercellular junctions. The study revealed a new finding: ZO-1 was also detected at the leading edge of lamellipodia, especially in motile wounded fibroblasts and in freshly plated fibroblasts, before the formation of cell–cell contacts. In fibroblast lysates, ZO-1 largely partitioned to the detergent-soluble fraction compared with myofibroblast lysates, indicating that much of the fibroblast ZO-1 is not associated with insoluble structural components. Lamellipodial ZO-1 colocalized with G-actin, α-actinin, and cortactin, which are proteins involved with actin remodeling and cell migration. Integrins α5β1 and αvβ3 also localized to the leading edge of migrating fibroblasts, and the association of ZO-1 with integrin was confirmed by immunoprecipitation. Finally, alkaline phosphatase treatment of fibroblast lysate decreased the molecular mass of ZO-1 in lysates of cells grown in serum, demonstrating that, in activated fibroblasts, ZO-1 is phosphorylated.
conclusions. ZO-1’s appearance at the leading edge of migrating fibroblasts makes it a candidate for a role in the initiation and organization of integrin-dependent fibroblast adhesion complexes formed during migration and adhesion. Further, phosphorylation of ZO-1 may regulate its cellular localization.
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