BINARY EXPRESSION OF OLFACTORY BULB-PROTEIN TYROSINE PHOSPHATASE IN RAT CENTRAL-NERVOUS-SYSTEM - DEVELOPMENTAL GENE-REGULATION IN NEONATE CEREBRAL-CORTEX AND CONSTITUTIVE EXPRESSION IN OLFACTORY-RHINENCEPHALON

Olfactory bulb-protein tyrosine phosphatase (OB-PTP) is a receptor typ e PTPase dominantly expressed in olfactory bulb. Previously, we isolat ed and molecularly cloned a rat OB-PTP cDNA from an embryonal brain cD NA library. In the present study, we investigated its temporal and spa tial gene expression by Northern blot and in situ hybridization analys is. The expression of OB-PTP gene was firstly detected in day 16 post coitum embryo and significantly increased during the late-gestational stage, attaining the highest level in the first week of neonate. The O B-PTP transcript was then down-regulated postnatally and was detected barely in an adult blain. In situ hybridization analysis showed that t he transcript was characteristically localized in the postmitotic neur ons of cerebral cortex and subcortical structures, and was down-regula ted by day 28 when the cortical and subcortical structures have been o rganized. In the olfactory-rhinencephalon system including olfactory b ulb and piriform cortex, the OB-PTP was preferentially expressed in th e postmitotic neurons, and in contrast continuously expressed in the m atured brain. Based on the evidence that DPTP10D, the Drosophila homol og of OB-PTP, is localized in the axons of specific pioneer neurons in Drosophila embryo, the OB-PTP is presumably involved in the axonogene sis of cortical and subcortical neurons as well as olfactory neurons i n mammalian central nervous system. The biological significance of tra nscriptional regulation in olfactory system is discussed in terms of c ontinuous axonal connections by regenerating olfactory neurons.