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Tyrosine phosphorylation of transmembrane ligands for Eph receptors
K Brückner1, E B Pasquale, R Klein
1European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany. USA.
Abstract:
Axonal pathfinding in the nervous system is mediated in part by cell-to-cell signaling events involving members of the Eph receptor tyrosine kinase (RTK) family and their membrane-bound ligands. Genetic evidence suggests that transmembrane ligands may transduce signals in the developing embryo. The cytoplasmic domain of the transmembrane ligand Lerk2 became phosphorylated on tyrosine residues after contact with the Nuk/Cek5 receptor ectodomain, which suggests that Lerk2 has receptorlike intrinsic signaling potential. Moreover, Lerk2 is an in vivo substrate for the platelet-derived growth factor receptor, which suggests crosstalk between Lerk2 signaling and signaling cascades activated by tyrosine kinases. It is proposed that transmembrane ligands of Eph receptors act not only as conventional RTK ligands but also as receptorlike signaling molecules.
Insights
Transmembrane ligands of Eph receptors, like Lerk2, may act as signaling molecules. Lerk2 phosphorylation suggests crosstalk between receptor tyrosine kinase (RTK) pathways and intrinsic signaling potential.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Axonal pathfinding is crucial for nervous system development.
- Eph receptor tyrosine kinases (RTKs) and their ligands mediate cell-to-cell signaling.
- Transmembrane ligands are implicated in embryonic signaling.
Purpose of the Study:
- To investigate the signaling potential of transmembrane ligands, specifically Lerk2.
- To explore the interaction between Lerk2 and Eph receptors.
- To understand the crosstalk between Lerk2 and other tyrosine kinase signaling pathways.
Main Methods:
- Investigated tyrosine phosphorylation of the Lerk2 cytoplasmic domain upon interaction with the Nuk/Cek5 receptor ectodomain.
- Assessed Lerk2 as an in vivo substrate for the platelet-derived growth factor receptor.
Main Results:
- The cytoplasmic domain of Lerk2 was phosphorylated on tyrosine residues after contact with the Nuk/Cek5 receptor ectodomain.
- Lerk2 functions as an in vivo substrate for the platelet-derived growth factor receptor.
- These findings suggest Lerk2 possesses receptor-like intrinsic signaling capabilities.
Conclusions:
- Transmembrane ligands of Eph receptors, exemplified by Lerk2, exhibit receptor-like signaling properties.
- Lerk2 signaling pathways may crosstalk with those activated by other tyrosine kinases.
- This dual role expands the understanding of Eph receptor-ligand interactions in developmental signaling.