The receptor tyrosine kinase Ror2 is involved in non-canonical Wnt5a/JNK signalling pathway. Oishi I et al. Ror2 is an orphan receptor, belonging to the Ror family of receptor tyrosine kinases. Although Ror2 has been shown to play crucial roles in developmental morphogenesis, the precise signalling events that Ror2 mediates remain elusive. Since Ror2 possesses an extracellular cysteine-rich domain (CRD) that resembles the Wnt-binding sites of the Frizzled (Fz) proteins, it is conceivable that Ror2 interacts with members of the Wnt family.
The orphan receptor tyrosine kinase Ror2 modulates canonical Wnt signaling in osteoblastic cells. Billiard J et al. Ror2 is an orphan receptor tyrosine kinase that plays crucial roles in developmental morphogenesis, particularly of the skeleton. We have identified human Ror2 as a novel regulator of canonical Wnt signaling in osteoblastic (bone-forming) cells with selective activities, enhancing Wnt1 but antagonizing Wnt3. Immunoprecipitation studies demonstrated physical interactions between human Ror2 and mammalian Wnt1 and Wnt3. Functionally, Ror2 antagonized Wnt1- and Wnt3-mediated stabilization of cytosolic beta-catenin in osteoblastic cells. However, Ror2 had opposing effects on a more distal step of canonical Wnt signaling: it potentiated Wnt1 activity but inhibited Wnt3 function as assessed by changes in Wnt-responsive reporter gene activity. Despite binding to Ror2, neither Wnt1 nor Wnt3 altered receptor activity as assessed by levels of Ror2 autophosphorylation. The ability of Ror2 to regulate canonical Wnt signaling in osteoblastic cells should have physiological consequences in bone, because Wnt signaling is known to modulate osteoblast survival and differentiation. Expression of Ror2 mRNA was highly regulated in a biphasic manner during human osteoblast differentiation, being virtually undetectable in pluripotent stem cells, increasing 300-fold in committed preosteoblasts, and disappearing again in osteocytes. Furthermore, Ror2 expression in osteoblasts was suppressed by the Wnt antagonist, secreted frizzled-related protein 1. The regulated expression of Ror2 during osteoblast differentiation, its inverse expression pattern with secreted frizzled-related protein 1, and its ability to modulate Wnt signaling in osteoblastic cells suggest that Ror2 may regulate bone formation.
NCBI Summary:
The protein encoded by this gene is a receptor protein tyrosine kinase and type I transmembrane protein that belongs to the ROR subfamily of cell surface receptors. The protein may be involved in the early formation of the chondrocytes and may be required for cartilage and growth plate development. Mutations in this gene can cause brachydactyly type B, a skeletal disorder characterized by hypoplasia/aplasia of distal phalanges and nails. In addition, mutations in this gene can cause the autosomal recessive form of Robinow syndrome, which is characterized by skeletal dysplasia with generalized limb bone shortening, segmental defects of the spine, brachydactyly, and a dysmorphic facial appearance. [provided by RefSeq, Jul 2008]
General function
Receptor, Enzyme
Comment
Cellular localization
Plasma membrane
Comment
Ovarian function
Germ cell development, Germ cell migration
Comment
Meiotic onset is reliant on spatial distribution but independent of germ cell number in the mouse ovary. Arora R et al. (2016) Mouse ovarian germ cells enter meiosis in a wave that propagates from anterior to posterior, but little is known about contribution of germ cells to initiation or propagation of meiosis. In a Ror2 mutant with diminished germ cell number and migration, we find that overall timing of meiotic initiation is delayed at the population level. We use chemotherapeutic depletion to exclude profoundly reduced number of germ cells as a cause for meiotic delay. We rule out sex reversal or failure to specify somatic support cells as contributors to the meiotic phenotype. Instead, we find that anomalies in the distribution of germ cells as well as gonad shape in mutants contribute to aberrant initiation of meiosis. Our analysis supports a model of meiotic initiation via diffusible signal(s), excludes a role for germ cells in commencing the meiotic wave and furnishes the first phenotypic demonstration of the wave of meiotic entry. Finally, our studies underscore the importance of considering germ cell migration defects while studying meiosis to discern secondary effects due to positioning versus primary meiotic entry phenotypes.//////////////////
Expression regulated by
FSH, LH
Comment
This gene was found through a series of mouse ovary microarray analyese.
Ovarian localization
Primordial Germ Cell, Oocyte
Comment
Novel domains of expression for orphan receptor tyrosine kinase Ror2 in the human and mouse reproductive system. Arora R 2014 et al.
Background: The non-canonical Wnt receptor and tyrosine kinase Ror2 has been associated with Recessive Robinow syndrome (RRS) and dominant Brachydactyly type B1. The phenotypes of mouse mutants implicate Ror2 in the development of the heart, lungs, bone and craniofacial structures, which are affected in RRS. Following a recently identified role of Ror2 in the migration of mouse primordial germ cells, we extensively characterized its expression throughout the fetal internal reproductive system and the postnatal ductal system. Results: We show that Ror2 gene products are present in the germ cells and somatic cells of the testis and the ovary of both the mouse and human fetus. In reproductive tract structures, we find that Ror2 is expressed in the mesonephros, developing Wolffian and M?an ducts and later in their derivatives, the epididymal epithelium and uterine epithelium. Conclusion: This study sets the stage to explore function for this tyrosine kinase receptor in novel regions of expression in the developing reproductive system in both mouse and human. Developmental Dynamics, 2014. ? 2014 Wiley Periodicals, Inc.
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Follicle stages
Comment
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: infertile - ovarian defect Comment: Ror2 enhances polarity and directional migration of primordial germ cells. Laird DJ 2012 et al.
The trafficking of primordial germ cells (PGCs) across multiple embryonic structures to the nascent gonads ensures the transmission of genetic information to the next generation through the gametes, yet our understanding of the mechanisms underlying PGC migration remains incomplete. Here we identify a role for the receptor tyrosine kinase-like protein Ror2 in PGC development. In a Ror2 mouse mutant we isolated in a genetic screen, PGC migration and survival are dysregulated, resulting in a diminished number of PGCs in the embryonic gonad. A similar phenotype in Wnt5a mutants suggests that Wnt5a acts as a ligand to Ror2 in PGCs, although we do not find evidence that WNT5A functions as a PGC chemoattractant. We show that cultured PGCs undergo polarization, elongation, and reorientation in response to the chemotactic factor SCF (secreted KitL), whereas Ror2 PGCs are deficient in these SCF-induced responses. In the embryo, migratory PGCs exhibit a similar elongated geometry, whereas their counterparts in Ror2 mutants are round. The protein distribution of ROR2 within PGCs is asymmetric, both in vitro and in vivo; however, this asymmetry is lost in Ror2 mutants. Together these results indicate that Ror2 acts autonomously to permit the polarized response of PGCs to KitL. We propose a model by which Wnt5a potentiates PGC chemotaxis toward secreted KitL by redistribution of Ror2 within the cell.//////////////