| First Author | Carbo C | Year | 2010 |
| Journal | J Leukoc Biol | Volume | 88 |
| Issue | 2 | Pages | 313-9 |
| PubMed ID | 20413728 | Mgi Jnum | J:163946 |
| Mgi Id | MGI:4830218 | Doi | 10.1189/jlb.0110049 |
| Citation | Carbo C, et al. (2010) Integrin-independent role of CalDAG-GEFI in neutrophil chemotaxis. J Leukoc Biol 88(2):313-9 |
| abstractText | Chemotaxis and integrin activation are essential processes for neutrophil transmigration in response to injury. CalDAG-GEFI plays a key role in the activation of beta1, beta2, and beta3 integrins in platelets and neutrophils by exchanging a GDP for a GTP on Rap1. Here, we explored the role of CalDAG-GEFI and Rap1b in integrin-independent neutrophil chemotaxis. In a transwell assay, CalDAG-GEFI-/- neutrophils had a 46% reduction in transmigration compared with WT in response to a low concentration of LTB4. Visualization of migrating neutrophils in the presence of 10 mM EDTA revealed that CalDAG-GEFI-/- neutrophils had abnormal chemotactic behavior compared with WT neutrophils, including reduced speed and directionality. Interestingly, Rap1b-/- neutrophils had a similar phenotype in this assay, suggesting that CalDAG-GEFI may be acting through Rap1b. We investigated whether the deficit in integrin-independent chemotaxis in CalDAG-GEFI-/- neutrophils could be explained by defective cytoskeleton rearrangement. Indeed, we found that CalDAG-GEFI-/- neutrophils had reduced formation of F-actin pseudopodia after LTB4 stimulation, suggesting that they have a defect in polarization. Overall, our studies show that CalDAG-GEFI helps regulate neutrophil chemotaxis, independent of its established role in integrin activation, through a mechanism that involves actin cytoskeleton and cellular polarization. |
