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Sck interacts with KDR and Flt-1 via its SH2 domain
K Igarashi1, K Shigeta, T Isohara
1Advanced Technology Research Laboratories, Nippon Steel Corporation, 3-35-1 Ida, Kawasaki, Nakahara-Ku, 211-0035, Japan. igarashi@lab1.nsc.co.jp
Abstract:
Vascular endothelial growth factor (VEGF) is one of the major angiogenesis regulators. It binds to its tyrosine kinase receptors, KDR and Flt-1. However, little is known about their downstream signal transduction properties. We screened human brain cDNA library using the yeast two-hybrid system with the KDR cytoplasmic region as bait to find KDR binding proteins. After 6.2 x 10(6) clones were screened, we identified Sck, one of the Shc homologues, as a KDR binding protein. Sck also binds to Flt-1 and their binding is dependent on the kinase activities of KDR and Flt-1. Extensive site-directed mutagenesis of KDR revealed that Y1175 of KDR is a major binding site for Sck. As Sck contains the SH2 domain and PTB domain, we tested whether they bind to KDR and Flt-1. The SH2 domain of Sck binds to both of them. Deletion of the SH2 domain from Sck resulted in the complete loss of binding. On the other hand, the PTB domain of Sck does not bind to KDR and Flt-1. These results indicate that Sck binds to KDR and Flt-1 via its SH2 domain and might play an important role in VEGF signal transduction.
Insights
This study identifies Sck as a protein that binds to vascular endothelial growth factor (VEGF) receptors KDR and Flt-1. This interaction, mediated by Sck's SH2 domain, is crucial for VEGF signal transduction.
Area of Science:
- Molecular Biology
- Cell Signaling
- Cancer Research
Background:
- Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis.
- VEGF signals through tyrosine kinase receptors KDR and Flt-1.
- Downstream signaling pathways of VEGF receptors are not fully understood.
Purpose of the Study:
- To identify proteins that bind to the KDR receptor.
- To investigate the role of these binding proteins in VEGF signal transduction.
Main Methods:
- Yeast two-hybrid screening of a human brain cDNA library using the KDR cytoplasmic region.
- Site-directed mutagenesis of KDR.
- Analysis of Sck protein domains (SH2 and PTB) for binding to KDR and Flt-1.
Main Results:
- Sck, a Shc homologue, was identified as a KDR binding protein.
- Sck also binds to Flt-1, dependent on receptor kinase activity.
- Tyrosine 1175 (Y1175) of KDR is a primary binding site for Sck.
- Sck binds to KDR and Flt-1 exclusively through its SH2 domain.
Conclusions:
- Sck interacts with VEGF receptors KDR and Flt-1 via its SH2 domain.
- Sck likely plays a significant role in mediating VEGF signal transduction pathways.
- Further research into Sck's function in angiogenesis and related diseases is warranted.