Expression and regulation of a gene encoding neural recognition molecule NB-3 of the contactin/F3 subgroup in mouse brain

NB-3 is a neural recognition molecule which is a member of contactin/F3 sub group in the immunoglobulin superfamily. We report here the developmental e xpression pattern and localization of NB-3 mRNA in mouse brain, determinati on of the NB-3 gene organization and identification of the promoter region. We also describe a splicing isoform of mouse NB-3, Mouse NB-3 exhibited 96 % identity with rat NB-3 at the amino acid sequence level. The splicing iso form lacked the amino acid residues between 62 and 78 of the original NB-3, which constituted a part of the first immunoglobulin-like domain. The expr ession of NB-3 mRNA was evident after birth, reaching a maximum at the post natal seventh day, and declined thereafter in the cerebrum, whereas the mRN A increased in the cerebellum to adulthood. In situ hybridization demonstra ted that NB-3 mRNA was preferentially expressed in the accessory olfactory bulb, layers II/III and V of the cerebral cortex, piriform cortex, anterior thalamic nuclei, locus coeruleus of the pens and mesencephalic trigeminal nucleus, and in Purkinje cells of the cerebellum The mouse NB-3 gene consis ted of 23 exons spanning more than 130 kb, The overall organization of the gene was similar to those of the F11, axonin-1 and TAX-1 genes of the subgr oup. By reporter gene analysis with the 5'-flanking region of the gene, we found a basal promoter activity in the 1.2 kb fragment upstream of the puta tive transcription initiation site. This study provides a basis for elucida ting the biological significance of the contactin/F3 subgroup molecules. (C ) 2000 Elsevier Science B.V. All rights reserved.