Isolation, characterisation, and chromosomal localisation of the mouse and human vasoactive intestinal peptide receptor type 2 genes

• Main Author: Mackay, Melanie E. H.
• Published: University of Edinburgh 1997
• Subjects: 572.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654273

As a result of hybridisation screening of a mouse genomic λ2001 library and a human genomic P1 library, 6 bacteriophage clones that together span the entire coding region of the mouse VIP<SUB>2</SUB> receptor (Vipr<SUB>2</SUB>) gene, and a single P1 clone that was shown to contain at least part of human VIP<SUB>2</SUB> receptor (VIPR2) gene, were isolated. Characterisation of the intron/exon structure of the mouse Vipr<SUB>2 </SUB> gene, achieved mainly by direct sequencing of λ DNA and PCR amplification of introns, revealed that the gene contained at least 12 introns, with sizes that range from 66 bp to at least 12 kb, and spans a minimum of 50 kb in total. Following the isolation of a 6 kb subclone which included the first exon and 5' sequence from the Vipr<SUB>2</SUB> gene, 3 kb of the putative promoter region of the gene was sequenced. The proximal 5' region of the Vipr<SUB>2</SUB> gene was found to be GC rich and CpG rich. No TATA box sequences were apparent within the region immediately upstream of the proposed transcription start site, but a computer-based search for possible transcription factor binding sites identified potential Sp1 and AP2 sites. Other potential regulatory sites that were found within the 3 kb sequence included possible binding sites for islet-1-like factors, the pituitary factor Pit-1, cAMP responsive factors, serum response factor, interferon stimulated gene factor-2, STAT factors, and factors that bind to the conserved lymphokine element 0. The chromosomal localisation of the VIP<SUB>2</SUB> receptor gene in human and mouse was determined through collaborative work, in which the VIPR2 P1 clone and a 4kb subclone from the mouse gene were used as probes in fluorescence <I>in situ</I> hybridisation experiments. The mouse gene was mapped to the telomeric region of mouse chromosome 12 (12F2), and the human gene was mapped to 7q36.3, within the previously defined minimal critical region for the brain developmental disorder holoprosencephaly type 3 (HPE3). More detailed mapping demonstrated that although one copy of the VIPR2 gene is deleted in some patients who have HPE3 and may contribute to the phenotype observed in these cases, it is not the gene responsible for HPE3.