Alternative titles; symbols
HGNC Approved Gene Symbol: GPBP1
Cytogenetic location: 5q11.2 Genomic coordinates (GRCh38) : 5:57,174,059-57,264,679 (from NCBI)
By subtractive hybridization for cDNAs expressed in atherosclerotic plaques with a thrombus, followed by screening an artery smooth muscle cell (SMC) cDNA library, Bijnens et al. (2003) cloned vasculin. Bioinformatic analysis detected vasculin variants resulting from alternative splicing of exon 3. The variant containing a start codon in exon 3 encodes a deduced 473-amino acid protein with a calculated molecular mass of 53 kD. Screening of a multiple-tissue mRNA dot blot with an exon 3-specific probe showed expression only in vascular SMCs. A probe that recognized other variants detected expression in nearly all tissues examined. Western blot analysis of atherosclerotic plaque lysates detected proteins with apparent molecular masses of 45 and 35 kD. The 45-kD protein was also detected in umbilical vein endothelial cells and plasma, and at lower levels in ovary and aorta. The 35-kD protein was detected in all tissues and cells examined. Immunohistochemical analysis of vascular samples revealed vasculin in the cytoplasm of SMCs, macrophages, and vascular endothelial cells, and immunohistochemical analysis of a wide range of tissues detected vasculin in other types of SMCs and endothelial cells, as well as in secretory cells.
Using the minimal self-sufficient promoter element (MSPE) of the GC-rich promoter of the mouse Ada gene (608958) as probe, Hsu et al. (2003) cloned Gpbp from a mouse brain cDNA library. The deduced 493-amino acid protein has a calculated molecular mass of 66 kD. Northern blot analysis detected ubiquitous expression of 3.0- and 3.5-kb Gpbp transcripts. These variants differ in the 3-prime polyadenylation site utilized.
Hsu et al. (2003) found that purified recombinant mouse Gpbp bound specifically to the MSPE of the mouse Ada gene promoter and to the GC-rich promoter of the nonhomologous human TOP2A gene (126430). In situ binding assays, immunoprecipitation, and Western blot analysis demonstrated that Gpbp is a nuclear factor that can form complexes with TATA-binding proteins, TFIIB (189963), TFIIF (see 189968), RNA polymerase II (see 180660), and p300 (602700)/CBP (600140) both in vitro and in intact cells. In cotransfection assays, increased Gpbp expression transactivated the promoter of the mouse Ada gene. Immunodepletion of GPBP in HeLa cell extracts reversibly suppressed extract-dependent in vitro transcription from the promoter of the mouse Ada gene. Transcription from the TATA box-containing GC-rich promoter of the human TOP2A gene was only partially suppressed.
Bijnens et al. (2003) determined that the vasculin gene contains 12 exons and spans 90 kb.
By genomic sequence analysis, Bijnens et al. (2003) mapped the vasculin gene to chromosome 5q11.2.
Bijnens, A. P. J. J., Gils, A., Jutten, B., Faber, B. C. G., Heeneman, S., Kitslaar, P. J. E. H. M., Tordoir, J. H. M., de Vries, C. J. M., Kroon, A. A., Daemen, M. J. A. P., Cleutjens, K. B. J. M. Vasculin, a novel vascular protein differentially expressed in human atherogenesis. Blood 102: 2803-2810, 2003. [PubMed: 12842993] [Full Text: https://doi.org/10.1182/blood-2003-01-0306]
Hsu, L.-C., Liu, S., Abedinpour, F., Beech, R. D., Lahti, J. M., Kidd, V. J., Greenspan, J. A., Yeung, C.-Y. The murine G+C-rich promoter binding protein mGPBP is required for promoter-specific transcription. Molec. Cell. Biol. 23: 8773-8785, 2003. [PubMed: 14612417] [Full Text: https://doi.org/10.1128/MCB.23.23.8773-8785.2003]