Identification of disulfide-linked dimers of the receptor tyrosine kinase DDR1
Rahim Abdulhussein1, Diana H H Koo, Wolfgang F Vogel
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada. rahim.abdulhussein@utoronto.ca
Abstract:
Discoidin domain receptor 1 (DDR1) is a transmembrane receptor tyrosine kinase activated by triple-helical collagen. So far six different isoforms of DDR1 have been described. Aberrant expression and signaling of DDR1 have been implicated in several human diseases linked to accelerated matrix degradation and remodeling, including tumor invasion, atherosclerosis, and lung fibrosis. Here we show that DDR1 exists as a disulfide-linked dimer in transfected as well as endogenously expressing cells. This dimer formation occurred irrespective of its kinase domain, as dimers were also found for the truncated DDR1d isoform. A deletion analysis of the extracellular domain showed that DDR1 mutants lacking the stalk region failed to form dimers, whereas deletion of the discoidin domain did not prevent dimerization. Point mutagenesis within the stalk region suggested that cysteines 303 and 348 are necessary for dimerization, collagen binding, and activation of kinase function. The identification of DDR1 dimers provides new insights into the molecular structure of receptor tyrosine kinases and suggests distinct signaling mechanisms of each receptor subfamily.
Insights
Discoidin domain receptor 1 (DDR1), a key kinase in diseases, forms disulfide-linked dimers. Specific cysteines in its stalk region are crucial for this dimerization, collagen binding, and kinase activation.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Medicine
Background:
- Discoidin domain receptor 1 (DDR1) is a transmembrane receptor tyrosine kinase.
- Six DDR1 isoforms are known, and aberrant DDR1 signaling is linked to diseases like cancer and fibrosis.
- DDR1 activation by collagen is critical in matrix remodeling and degradation.
Purpose of the Study:
- To investigate the structural basis of DDR1 function.
- To determine if DDR1 forms dimers and identify the regions involved.
- To elucidate the role of specific amino acids in DDR1 dimerization and activation.
Main Methods:
- Transfection and endogenous expression of DDR1 and its mutants.
- Disulfide bond analysis to detect dimer formation.
- Deletion and point mutagenesis of the extracellular domain.
- Collagen binding assays and kinase activity measurements.
Main Results:
- DDR1 forms disulfide-linked dimers in cells, independent of its kinase domain.
- Dimerization requires the stalk region but not the discoidin domain.
- Cysteines 303 and 348 in the stalk region are essential for dimerization, collagen binding, and kinase activation.
Conclusions:
- DDR1 exists as a disulfide-linked dimer, providing new insights into receptor tyrosine kinase structure.
- The stalk region, particularly cysteines 303 and 348, is critical for DDR1 dimerization and function.
- Understanding DDR1 dimerization may reveal novel signaling mechanisms and therapeutic targets for DDR1-associated diseases.
Related Concept Videos
01:26Receptor Tyrosine Kinases
01:00Enzyme-linked Receptors
Neurotrophin (NT) receptors are a family of RTKs, including trkA, trkB, and trkC (tropomyosin-related kinase) receptors. TrkA is specific for nerve growth factor (NGF), neurotrophin-6, and neurotrophin-7. TrkB binds...