In:
Journal of Leukocyte Biology, Oxford University Press (OUP), Vol. 88, No. 2 ( 2010-04-22), p. 313-319
Abstract:
CalDAG-GEFI regulates neutrophil chemotaxis independent of integrin function by a mechanism that involves F-actin distribution and cell polarization. Chemotaxis and integrin activation are essential processes for neutrophil transmigration in response to injury. CalDAG-GEFI plays a key role in the activation of β1, β2, and β3 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.
Type of Medium:
Online Resource
ISSN:
1938-3673
,
0741-5400
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2010
detail.hit.zdb_id:
2026833-6
SSG:
12
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