Brain specific proteins binding to the 3' UTR of the 5-HT2C receptor mRNA

Comparative genomic analysis of slc39a12/ZIP12: insight into a zinc transporter required for vertebrate nervous system development

The zinc transporter ZIP12, which is encoded by the gene slc39a12, has previously been shown to be important for neuronal differentiation in mouse Neuro-2a neuroblastoma cells and primary mouse neurons and necessary for neurulation during Xenopus tropicalis embryogenesis. However, relatively little is known about the biochemical properties, cellular regulation, or the physiological role of this gene. The hypothesis that ZIP12 is a zinc transporter important for nervous system function and development guided a comparative genetics approach to uncover the presence of ZIP12 in various genomes and identify conserved sequences and expression patterns associated with ZIP12. Ortholog detection of slc39a12 was conducted with reciprocal BLAST hits with the amino acid sequence of human ZIP12 in comparison to the human paralog ZIP4 and conserved local synteny between genomes. ZIP12 is present in the genomes of almost all vertebrates examined, from humans and other mammals to most teleost fish. However, ZIP12 appears to be absent from the zebrafish genome. The discrimination of ZIP12 compared to ZIP4 was unsuccessful or inconclusive in other invertebrate chordates and deuterostomes. Splice variation, due to the inclusion or exclusion of a conserved exon, is present in humans, rats, and cows and likely has biological significance. ZIP12 also possesses many putative di-leucine and tyrosine motifs often associated with intracellular trafficking, which may control cellular zinc uptake activity through the localization of ZIP12 within the cell. These findings highlight multiple aspects of ZIP12 at the biochemical, cellular, and physiological levels with likely biological significance. ZIP12 appears to have conserved function as a zinc uptake transporter in vertebrate nervous system development. Consequently, the role of ZIP12 may be an important link to reported congenital malformations in numerous animal models and humans that are caused by zinc deficiency.

Control of mu opioid receptor expression by modification of cDNA 5'- and 3'-noncoding regions

Removal of a 712 base pair (bp) sequence following the coding region of a human micro opioid receptor (hmuOR) cDNA unexpectedly increased expression of the receptor protein. A series of 3'-noncoding region deletion mutants revealed that at least three discrete regions following the stop codon influenced receptor expression levels. Deletion of the 205-bp 5'-noncoding region immediately preceding the Kozak sequence doubled receptor expression relative to wild type, and simultaneous deletion of 5'- and 3'-noncoding regions increased expression several fold. The hmuOR noncoding regions may participate in a regulatory mechanism that controls the number of cell surface receptors.

Structure of the human VIPR2 gene for vasoactive intestinal peptide receptor type 2

The VPAC(2) (vasoactive intestinal peptide (VIP)(2)) receptor is a seven-transmembrane spanning G protein-coupled receptor which responds similarly to VIP and pituitary adenylate cyclase activating polypeptide (PACAP) in stimulating cAMP production. Recently, we reported the localisation of the human VPAC(2) receptor gene (VIPR2) to chromosome 7q36.3 (Mackay, M. et al. (1996) Genomics 37, 345-353). Here, we describe the characterisation of the VIPR2 gene structure and promoter region. The VIPR2 gene is encoded by 13 exons, the initiator codon of the 438 amino acid open reading frame is located in exon 1 and the termination signal and a poly-adenylation signal sequence are located in exon 13. The 5' untranslated region extends 187 bp upstream of the initiator codon and is extremely GC-rich (80%). The poly-adenylation signal is located 2416 bp downstream of the stop codon. Intron sizes range from 68 bp (intron 11) to 45 kb (intron 4) and the human gene spans 117 kb.