Genomic characterization of the human and mouse protein tyrosine phosphatase-1B genes.
PTP-1B is a ubiquitously expressed intracellular protein tyrosine phosphatase (PTP) that has been implicated in the negative regulation of insulin signaling. Mice deficient in PTP-1B were found to have an enhanced insulin sensitivity and a resistance to diet-induced obesity. Interestingly, the human PTP-1B gene maps to chromosome 20q13.1 in a region that has been associated with diabetes and obesity. Although there has been a partial characterization of the 3' end of the human PTP-1B gene, the complete gene organization has not been described. In order to further characterize the PTP-1B gene, we have cloned and determined the genomic organization for both the human and mouse PTP-1B genes including the promoter. The human gene spans >74 kb and features a large first intron of >54 kb; the mouse gene likewise contains a large first intron, although the exact size has not been determined. The organization of the human and mouse PTP-1B genes is identical except for an additional exon at the 3' end of the human that is absent in the mouse. The mouse PTP-1B gene maps to the distal arm of mouse chromosome 2 in the region H2-H3. This region is associated with a mouse obesity quantitative trait locus (QTL) and is syntenic with human chromosome 20. The promoter region of both the human and mouse genes contain no TATA box but multiple GC-rich sequences that contain a number of consensus SP-1 binding sites. The basal activity of the human PTP-1B promoter was characterized in Hep G2 cells using up to 8 kb of 5' flanking sequence. A 432 bp promoter construct immediately upstream of the ATG was able to confer maximal promoter activity. Within this sequence, there are at least three GC-rich sequences and one CCAAT box, and deletion of any of these elements results in decreased promoter activity. In addition, the promoter in a number of mouse strains contains, 3.5 kb upstream of the start codon, an insertion of an intracisternal a particle (IAP) element that possibly could alter the expression of PTP-1B mRNA in these strains.
Forsell
P A
PA
Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, Kirkland, Quebec H9H 3L1, Canada.
Boie
Y
Y
Montalibet
J
J
Collins
S
S
Kennedy
B P
BP
D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005091:Exons; D015870:Gene Expression; D005786:Gene Expression Regulation; D005796:Genes / Q000235:genetics*; D007426:Genes, Intracisternal A-Particle / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007438:Introns; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011401:Promoter Regions, Genetic / Q000235:genetics; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D004247:DNA; D000469:Alkaline Phosphatase; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; C516609:Ptpn1 protein, mouse