Orphan nuclear receptor RORα gene: Isoform-specific spatiotemporal expression during postnatal development of brain

We analyzed expression of mouse orphan nuclear receptor RORα during postnatal development of rodent brain. Using a riboprobe corresponding to the 3'-end of mRORα cDNA, a peak of RORα: expression was observed at postnatal 16 day (P16) in the Purkinje cells of cerebellum, neurons of the thalamus and the olfactory bulb. The hippocampus was also shown to express RORα with an earlier peak at P7. Expression in cell types other than the Purkinje cells appeared transient. On the other hand, when a probe to the 5'-end of mRORα cDNA was used, we observed patterns of RORα expression that are different from those observed with the 3'-probe. No specific transcripts of RORα were detected with the 5'-probe in the Purkinje cells until P16. Additionally, the relative level of the hybridization signals with the 5'-probe and the 3'-probe were different among the various brain regions. Together with the previous findings that RORα comprises at least four isoforms which differ from one another in their N-terminal regions, these observations suggest that the spatiotemporal expression of RORα is under isoform-specific regulation. The timing of its expression suggests that RORα may be involved in regulation of postnatal maturation of specific classes of neurons.