Characterization of the 5'-flanking region of the murine polymeric IgA receptor gene.
The regulatory elements that control basal and activated transcriptional expression of the polymeric IgA receptor gene (pIgR) have not been defined. In this study, we performed functional analysis of the murine pIgR 5'-upstream region. Transient transfection studies identified the gene's minimal promoter to reside within 110 nucleotides upstream from the start of transcription. Substitution mutations of this region identified both a putative activator (-78 to -70) and a repressor (-66 to -52) element. DNase I footprint analysis confirmed an area of protection that spans from nucleotides -85 to -62. Mobility shift assays of the putative region confirmed binding of upstream stimulatory factor 1 (USF1) to an E box element at positions -75 and -70, representing the putative enhancer. Overexpression studies using various forms of USF suggest that both USF1 and USF2 enhance activity of the pIgR minimal promoter. We report the identification and characterization of the murine pIgR minimal promoter, as well as the critical role of USF in enhancing its basal level of transcription in Caco-2 cells.
Division of Gastroenterology and Nutrition, Department of Pediatrics, University of California School of Medicine, Los Angeles, California 90095-1752, USA.
M G
MG
Martín
J
J
Wang
T W
TW
Li
J T
JT
Lam
E M
EM
Gutierrez
R S
RS
Solorzano-Vargas
A H
AH
Tsai
D000375:Aging; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005091:Exons; D015698:Genomic Library; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007421:Intestine, Small / Q000254:growth & development / Q000378:metabolism*; D051379:Mice / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D051381:Rats / Q000235:genetics; D011961:Receptors, Fc / Q000096:biosynthesis / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016385:TATA Box; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; C045281:IgA receptor; D007070:Immunoglobulin A; D009838:Oligodeoxyribonucleotides; D011961:Receptors, Fc; D011994:Recombinant Proteins