Xenbase Image ID: 144398

Figure 5. Integrin Ligation Regulates Cadherin Adhesion and Is Independent of Receptor Levels at Cell Surface or FAK Phosphorylation. (A) Animal cap blastomeres expressing HA adhere strongly to the FC-cadherin fusion protein (HA, 86 ± 12%), while activin decreases blastomere adhesion (HA + ACTIVIN, 57 ± 3.7%). Coincubation of activin-induced animal cap cells with 15 μg/ml of the GST-9.11 fusion protein encompassing the CCBD of FN restores adhesion to cadherin (HA + ACTIVIN + 9.11, 84 ± 4.5%). Cells expressing HAβ1 show reduced adhesion to the cadherin substrate (HAβ1, 65 ± 2.5%). This reduced adhesion is independent of activin induction (HAβ1 + ACTIVIN, 66 ± 7.5) and cannot be rescued with the FN fusion protein (HAβ1 + ACTIVIN + 9.11, 62 ± 4.9%). (B and C) (B) Immunoprecipitation of cadherin and integrin receptors from surface-biotinylated DMZ cells reveals that surface expression of cadherins is unchanged between uninjected (CONT), HA-injected (HA), and HAβ1-injected (HAβ1) embryos. Similarly, surface levels of β1 integrins remain unchanged under the same conditions. Cadherins and integrins were immunoprecipitated with a polyclonal Ab (Xcad) and mAb 8C8, respectively, and were detected with avidin HRP. Integrin profiles reveal the presence of β1 and associated α subunits. (C) Immunoprecipitation of FAK from HA- or HAβ1-expressing embryos does not reveal differences in either the total amount of FAK or the level of phosphorylated FAK. Image published in: Marsden M and DeSimone DW (2003) Copyright © 2003. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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