Overexpression of receptor-type protein tyrosine phosphatase beta causes abnormal development of the cranial nerve in Xenopus embryos.

Roles of receptor-type protein tyrosine phosphatase beta (RPTPbeta, also called PTPzeta) were investigated in the nervous system development of Xenopus embryos. We previously showed that Xenopus embryos express mRNAs for 11 receptor-type (XRPTPbeta.1-XRPTPbeta.11) and two secretory (sXRPTPbeta.1 and sXRPTPbeta.2) variants generated by alternative RNA splicing. Whole-mount in situ hybridization analyzes demonstrated central nervous system-specific gene transcription in tailbud embryos. Distributions of mRNAs for receptor-type and secretory variants partially differ in the hindbrain. Overexpression of XRPTPbeta.4 or sXRPTPbeta.2, which was brought about by microinjection of the recombinant plasmid vectors, caused abnormal development of the cranial nerve X. Deletion of the cytoplasmic segment from XRPTPbeta.4 did not affect the ability to cause the abnormality, but deletion of the extracellular segment abolished it. These results suggest that normal development of the cranial nerve X requires regulated expression of the XRPTPbeta gene products.