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Signaling via Src family kinases is required for normal internalization of the receptor c-Kit
V C Broudy1, N L Lin, W C Liles
1Divisions of Hematology, Department of Medicine, University of Washington, Seattle, WA, USA. vcbroudy@u.washington.edu
Abstract:
Stem cell factor (SCF) exerts its biological effects by binding to a specific receptor, the tyrosine kinase c-Kit, which is expressed on the cell surface. Although normal cellular trafficking of growth factor receptors may play a critical role in the modulation of receptor function, the mechanisms that regulate the distribution of c-Kit on the cell surface and the internalization of c-Kit have not been fully defined. We investigated whether signal transduction via Src family kinases is required for normal c-Kit trafficking. Treatment of the SCF-responsive human hematopoietic cell line MO7e with the inhibitor of Src family kinases PP1 blocked SCF-induced capping of c-Kit and internalization of c-Kit. c-Kit was able to associate with clathrin in the presence of PP1, suggesting that entry of c-Kit into clathrin-coated pits occurs independently of Src family kinases. SCF-induced internalization of c-Kit was also diminished in the D33-3 lymphoid cell line in which expression of Lyn kinase was disrupted by homologous recombination. These results indicate that Src family kinases play a role in ligand-induced trafficking of c-Kit.
Insights
Src family kinases are essential for the trafficking and internalization of the c-Kit receptor upon stem cell factor (SCF) binding. Inhibiting these kinases blocks key c-Kit cell surface distribution processes.
Area of Science:
- Cell Biology
- Molecular Biology
- Hematopoiesis
Background:
- Stem cell factor (SCF) binding to its receptor, tyrosine kinase c-Kit, regulates cellular functions.
- Understanding c-Kit cell surface trafficking and internalization is crucial for modulating its function.
- The role of Src family kinases in c-Kit trafficking remains incompletely understood.
Purpose of the Study:
- To investigate the requirement of Src family kinases in stem cell factor-induced c-Kit trafficking.
- To elucidate the mechanisms regulating c-Kit cell surface distribution and internalization.
Main Methods:
- Utilized the SCF-responsive human hematopoietic cell line MO7e.
- Employed the Src family kinase inhibitor PP1.
- Investigated c-Kit association with clathrin.
- Examined c-Kit trafficking in Lyn kinase-deficient lymphoid cell line D33-3.
Main Results:
- PP1 treatment inhibited SCF-induced capping and internalization of c-Kit.
- c-Kit association with clathrin occurred independently of Src family kinases.
- SCF-induced c-Kit internalization was reduced in Lyn kinase-disrupted cells.
Conclusions:
- Src family kinases are critical mediators of ligand-induced c-Kit trafficking.
- These kinases play a significant role in regulating c-Kit cell surface dynamics and internalization pathways.