Characterization of the human Glvr-1 phosphate transporter/retrovirus receptor gene and promoter region.
The cell surface receptor for gibbon ape leukemia virus (Glvr-1) belongs to the type III sodium-dependent phosphate transporter/retrovirus receptor gene family. Several observations have suggested an important role for Glvr-1 in regulated Pi handling in bone forming cells and prompted us to investigate further the molecular mechanisms regulating Glvr-1 gene expression. In addition, the regulation of Glvr-1 gene expression also has potential applications to gene therapy, since retroviral vectors carrying gibbon ape leukemia virus envelope proteins are used for gene delivery into different cell types. The aim of this study was thus to clone the human Glvr-1 gene in order to describe its structure and its promoter region. Our results indicate that the Glvr-1 gene consists of 11 exons and 10 introns spread over 18kb of genomic DNA. The translation initiation site is located within exon II and the translation stop codon within exon XI. Rapid amplification of cDNA ends (5'-RACE) suggests that, in human SaOS-2 osteoblast-like cells, transcription of Glvr-1 is initiated at multiple sites, mostly located between bp 32 and 50 of the published cDNA sequence, which was initially obtained from HL-60 cells. The 5'-flanking region of the gene is characterized by a very high GC content. Reporter gene assays demonstrate the presence of a functional promoter upstream of exon I and indicate that a GC-rich region, containing two potential SP1 binding sites, is required for high promoter activity in transiently transfected SaOS-2 cells. The description of the human Glvr-1 gene structure, as well as the analysis of some structural and functional characteristics of its promoter region, provide a basis for more detailed investigation of the molecular mechanisms controlling expression of the Glvr-1 gene in bone forming cells and in other cell types.
Palmer
G
G
Division of Bone Diseases, WHO Collaborating Center for Osteoporosis and Bone Diseases, Department of Internal Medicine, University Hospital, Geneva, Switzerland.
Manen
D
D
Bonjour
J P
JP
Caverzasio
J
J
D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000502:physiology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D011991:Receptors, Virus / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D012333:RNA, Messenger; D011991:Receptors, Virus; D011994:Recombinant Proteins; C067981:leukemia virus receptor, gibbon ape