High impact information on Ryk

• The Ryk receptor belongs to the atypical receptor tyrosine kinase family [1].
• Ryk-deficient mice exhibit craniofacial defects associated with perturbed Eph receptor crosstalk [2].
• Here we demonstrate that the mouse orphan receptor 'related to tyrosine kinases' (Ryk) is essential for normal development and morphogenesis of craniofacial structures including the secondary palate [2].
• Thus, Ror2 encodes a receptor-like tyrosine kinase that is selectively expressed in, and particularly important for, the chondrocyte lineage [3].
• TIE2 is a receptor-like tyrosine kinase expressed almost exclusively in endothelial cells and early hemopoietic cells and required for the normal development of vascular structures during embryogenesis [4].

Biological context of Ryk

• Quantitative reduction of Southern blotting stringency for the detection of Ryk-related sequences provided evidence for a retroprocessed mouse pseudogene and a more distantly related gene paralogue [5].
• Flow cytometric analysis with a monospecific anti-Ryk Ab demonstrates that Ryk+ cells constitute 36.7% and Lin+/Ryk+ cells constitute 33.7% of low density bone marrow cells whereas Ryk+ cells represent only 0.3% of the Lin- population [6].
• This hypothesis is supported by the multiple developmental phenotypes apparent in Ryk loss-of-function mice [7].

Anatomical context of Ryk

• Ryk RNA is present at greatly increased levels in cells at particular stages of epithelial differentiation: the basal layer of skin and tongue epithelia, the intervillous layer and some crypt bases of the intestine and the lower matrix region of the hair follicle [8].
• Ryk-mediated Wnt repulsion regulates posterior-directed growth of corticospinal tract [9].
• In summary, this study expands the emerging role for Wnts in axon guidance and identifies Ryk as a key guidance receptor in the establishment of the corpus callosum [10].
• Recently, Ryk-Wnt interactions were shown to guide corticospinal axons down the embryonic mouse spinal cord [10].
• Ror2, encoding a receptor-like tyrosine kinase, is required for cartilage and growth plate development [3].

Regulatory relationships of Ryk

• Recent genetic analyses of mouse Ryk and its Drosophila orthologue derailed have defined a role for this novel subfamily of receptors in the control of craniofacial development and neuronal pathway selection, respectively [11].
• Ryk is expressed in a differentiation-specific manner in epithelial tissues and is strongly induced in decidualizing uterine stroma [8].

Other interactions of Ryk

• Two distinct Ryk loci (Ryk-1 and Ryk-2) were identified [12].
• The Wnt receptor Ryk is required for Wnt5a-mediated axon guidance on the contralateral side of the corpus callosum [10].
• We also show that Wnt5a acts as a chemorepulsive ligand for Ryk, driving callosal axons toward the contralateral hemisphere after crossing the midline [10].
• Isolation and characterization of Bsk, a growth factor receptor-like tyrosine kinase associated with the limbic system [13].

References