Characterization of the chromosomal gene and promoter for human insulin-like growth factor binding protein-5.
To better understand the regulation of insulin-like growth factor binding protein-5 (IGFBP-5) expression, we cloned the IGFBP-5 gene from human genomic libraries and identified a region in the 5' flanking sequence which functions as a promoter. The human IGFBP-5 gene is divided into four exons which, primarily due to a first intron of approximately 25 kilobases, span approximately 33 kilobases of DNA. Southern analysis identified a single copy of the IGFBP-5 gene in the haploid human genome, and several independent mapping strategies found this gene tightly linked with, and in opposite transcriptional orientation to, the IGFBP-2 gene at chromosomal region 2q33-34. Primer extension studies identified the IGFBP-5 mRNA cap site 772 base pairs (bp) 5' to the first nucleotide of the translation start codon. Analysis of the 5'-flanking sequence identified a potential TATA element beginning 33 bp 5' to the mRNA cap site. When a DNA fragment containing this cap site and 461 bp of upstream sequence was placed 5' to the chloramphenicol acetyltransferase reporter gene and transfected into MDA-MB-468 human breast cancer cells, it directed chloramphenicol acetyltransferase expression in an orientation-specific manner, suggesting that this region contains elements essential for IGFBP-5 promoter activity.
Allander
S V
SV
Department of Clinical Genetics, Karolinska Institute, Stockholm, Sweden.
Larsson
C
C
Ehrenborg
E
E
Suwanichkul
A
A
Weber
G
G
Morris
S L
SL
Bajalica
S
S
Kiefer
M C
MC
Luthman
H
H
Powell
D R
DR
D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D002874:Chromosome Mapping; D002877:Chromosomes, Human; D018076:DNA, Complementary; D006801:Humans; D018975:Insulin-Like Growth Factor Binding Protein 5; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D018076:DNA, Complementary; D018975:Insulin-Like Growth Factor Binding Protein 5; D012333:RNA, Messenger; D013002:Somatomedins