LOCALIZATION OF TRANSCRIPTS OF THE RELATED NUCLEAR ORPHAN RECEPTORS COUP-TF-I AND ARP-1 IN THE ADULT-MOUSE BRAIN

The chicken ovalbumin upstream promoter transcription factor, COUP-TF I, and the protein ARP-1 (COUP-TF II) are two highly homologous orphan receptors of the nuclear hormone receptor family. In this study we in vestigated their expression patterns in the adult nervous system of th e mouse. In situ hybridizations were performed on brain sections with S-35-labeled cRNA probes derived from the 3'-non-coding regions of the mARP-1 and mCOUP-TF I mRNAs. Both COUP-TF I and ARP-1 were shown to b e expressed in the adult brain and they displayed restricted and disti nct expression patterns. COUP-TF I transcripts were predominantly foun d in the rostral and caudal parts of the adult mouse brain, whereas AR P-I transcripts prevaled in the middle part of the brain. High express ion of COUP-TF I was detected in the olfactory nucleus, in neocortex l ayers I/II and V/VI, in the dentate gyrus and in areas CA1/CA3/CA4 of the hippocampus, and in the granular layer of the cerebellum. Only low amounts of COUP-TF I mRNA were detected in the ventral, the laterodor sal and in the interanteromedial thalamic nuclei. Small amounts of COU P-TF I transcripts were also found in the epithelial layer of the vent ricle and in arachnoid membranes. High expression of ARP-I was detecte d in the reticular, the ventral lateral and the gelatinosus thalamic n uclei. Other hot spots of ARP-1 mRNA expression were the amygdaloid nu cleus and the arachnoid membranes. Lower amounts of ARP-1 transcripts were found in the anterior and lateral hypothalamic areas, in the supr achiasmatic nucleus, and in the choroid plexus. Overlapping expression of COUP-TF I and ARP-1 mRNA was only found in the ventral lateral tha lamic nucleus. These expression patterns do not coincide with a partic ular neuronal phenotype. The distinct distributions suggest different functional roles for each of the corresponding gene products in the ma ture nervous system.