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Analysis of tyrosine phosphorylation-dependent protein-protein interactions in TrkB-mediated intracellular signaling
M Yamada1, K Suzuki, M Mizutani
1Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan. yamada@protein.osaka-u.ac.jp
Abstract:
Activated receptor tyrosine kinases induce a large number of tyrosine phosphorylation-dependent protein-protein interactions through which they mediate their various ligand-exerted functions including regulation of proliferation, differentiation and survival. TrkB receptor tyrosine kinase activated by binding of brain-derived neurotrophic factor (BDNF) also stimulates various protein interactions in a tyrosine phosphorylation-dependent manner in neuronal cells. To examine tyrosine phosphorylation-dependent interactions stimulated by active TrkB, we developed a modified yeast two-hybrid system, which we call the yeast two-and-a-half-hybrid system. In this system, yeast was engineered to express a tyrosine kinase domain of TrkB as an effector, in addition to two fusion proteins with GAL4 DNA-binding and GAL4 activation domains as bait and prey proteins, respectively. Using this system with Shp2 as the bait, we demonstrated that Shp2 interacts directly with BIT/SHPS-1 (also called SIRP) and Grb2 depending on tyrosine phosphorylation mediated by TrkB. Furthermore, we screened an adult human brain cDNA library with the yeast two-and-a-half-hybrid system in order to identify other Shp2-binding proteins in TrkB-stimulated tyrosine phosphorylation signaling. We found that fibroblast growth factor receptor substrate 2beta (FRS2beta), also called SNT2, interacts with Shp2 dependently on TrkB-mediated tyrosine phosphorylation of FRS2beta/SNT2. Therefore, we show that the two-and-a-half-hybrid system is a powerful tool for studying tyrosine phosphorylation-dependent protein-protein interactions in intracellular signaling pathways stimulated by TrkB receptor tyrosine kinase.
Insights
Researchers developed a novel yeast two-and-a-half-hybrid system to study protein interactions. This system identified new binding partners for Shp2 in brain-derived neurotrophic factor (BDNF) signaling pathways.
Area of Science:
- Molecular Biology
- Cell Signaling
- Neuroscience
Background:
- Receptor tyrosine kinases (RTKs) regulate cell functions via tyrosine phosphorylation-dependent protein interactions.
- The TrkB receptor tyrosine kinase, activated by BDNF, mediates crucial neuronal functions through similar signaling mechanisms.
Purpose of the Study:
- To develop a novel method for identifying tyrosine phosphorylation-dependent protein interactions.
- To investigate Shp2-binding proteins involved in TrkB-mediated signaling.
Main Methods:
- Development of a modified yeast two-hybrid system termed the yeast two-and-a-half-hybrid system.
- Engineering yeast to express TrkB tyrosine kinase domain and GAL4-fused bait/prey proteins.
- Screening an adult human brain cDNA library using the developed system.
Main Results:
- The yeast two-and-a-half-hybrid system successfully identified Shp2 interactions with BIT/SHPS-1 and Grb2, dependent on TrkB-mediated tyrosine phosphorylation.
- Fibroblast growth factor receptor substrate 2beta (FRS2beta/SNT2) was identified as a novel Shp2-interacting protein in TrkB signaling.
Conclusions:
- The yeast two-and-a-half-hybrid system is effective for studying tyrosine phosphorylation-dependent protein interactions.
- New insights into TrkB-mediated intracellular signaling pathways were gained through the identification of novel Shp2-binding proteins.