EXPRESSION OF PTPH1, A RAT PROTEIN-TYROSINE-PHOSPHATASE, IS RESTRICTED TO THE DERIVATIVES OF A SPECIFIC DIENCEPHALIC SEGMENT

Studies to date have identified only a few proteins that are expressed in a segment-specific manner within the mammalian brain. Here we repo rt that a nonreceptor protein tyrosine phosphatase, PTPH1, is selectiv ely expressed in the adult thalamus. Expression of PTPH1 mRNA is detec ted in most, but not all, thalamic nuclei, Nuclei that are derived emb ryonically from the dorsal thalamus and project to the neocortex expre ss this gene, whereas those derived from the ventral thalamus do not. PTPH1 mRNA expression is also restricted to the dorsal thalamus during development and, thus, can serve as a specific marker for the dorsal thalamic nuclei. Since the subcellular localization of PTPH1 protein i s not known, its functional role is not clear. However, the restrictio n of its expression to the thalamic nuclei that have thalamocortical c onnections suggests that PTPH1 may play a role in the maintenance of t hese connections or in determining the physiological properties of tha lamic relay nuclei.