ORPHAN NUCLEAR RECEPTOR ROR-ALPHA GENE - ISOFORM-SPECIFIC SPATIOTEMPORAL EXPRESSION DURING POSTNATAL-DEVELOPMENT OF BRAIN

We analyzed expression of mouse orphan nuclear receptor ROR alpha duri ng postnatal development of rodent brain. Using a riboprobe correspond ing to the 3'-end of mROR alpha cDNA, a peak of ROR alpha expression w as observed at postnatal 16 day (P16) in the Purkinje cells of cerebel lum, neurons of the thalamus and the olfactory bulb. The hippocampus w as also shown to express ROR alpha with an earlier peak at P7. Express ion in cell types other than the Purkinje cells appeared transient, On the other hand, when a probe to the 5'-end of mROR alpha cDNA was use d, we observed patterns of ROR alpha expression that are different fro m those observed with the 3'-probe, No specific transcripts of ROR alp ha were detected with the 5'-probe in the Purkinje cells until P16. Ad ditionally, the relative level of the hybridization signals with the 5 '-probe and the 3'-probe were different among the various brain region s. Together with the previous findings that ROR alpha comprises at lea st four isoforms which differ from one another in their N-terminal reg ions, these observations suggest that the spatiotemporal expression of ROR alpha is under isoform-specific regulation. The timing of its exp ression suggests that ROR alpha may be involved in regulation of postn atal maturation of specific classes of neurons.