Lfc is a Rho specific guanine nucleotide exchange factor (GEF) that is bound and inhibited by the microtubule (MT) cytoskeleton. In epithelial cells, Lfc promotes actomyosin contractility in response to MT depolymerization; however, its role in leukocytes has not been assessed. Through genetic ablation, we generated an Lfc knockout mouse (Lfc-/-) and tested biochemical and cell biological responses to MT depolymerization in bone marrow derived cells. Lfc was necessary for characteristic actomyosin based contractile behaviours of neutrophils and macrophages, in response to MT depolymerization.
Gout is a painful arthritic inflammatory disease, caused by buildup of monosodium urate (MSU) crystals in the joints. Colchicine, a MT-depolymerizing agent that is used in prophylaxis and treatment of acute gout flare, blocks neutrophil infiltration to sites of MSU crystal-induced inflammation. We found that Lfc was necessary for the ability of colchicine to inhibit MSU-induced neutrophil infiltration in two in vivo models of gout-like inflammation.
Efficient recruitment of leukocytes from the vasculature is a critical step in the immune response to infection. Leukocyte extravasation, which includes rolling, crawling, and diapedesis across the endothelial barrier, is enhanced by fluid shear stress. Through comparison of Lfc+/+ and Lfc-/- mice, we found that Lfc was necessary for in vivo leukocyte crawling and emigration out of the vasculature. Lfc-/- mice also showed defective neutrophil infiltration in response to acute inflammatory insults, and increased mortality in response to polymicrobial infection. In vitro, we found that Lfc was necessary for neutrophil responses to shear stress.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/33893 |
| Date | 06 December 2012 |
| Creators | Fine, Noah A. |
| Contributors | Rottapel, Robert |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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