Vol. 283, Issue 2, G415-G425, August 2002
Multiple transcription factors in 5'-flanking region of human
polymeric Ig receptor control its basal expression
R. Sergio
Solorzano-Vargas1,
Jiafang
Wang2,
Lingling
Jiang2,
Hugh V.
Tsai2,
Luis O.
Ontiveros2,
Mukta A.
Vazir1,
Renato J.
Aguilera3, and
Martín G.
Martín2
2 Department of Pediatrics, Division of
Gastroenterology and Nutrition, and 3 Department of
Molecular, Cell, and Developmental Biology, School of Medicine,
University of California, Los Angeles 90095; and
1 Department of Biology, California State
University, Northridge, California 91330
The polymeric Ig receptor
(pIgR) is a critical component of the mucosal immune system
and is expressed in largest amounts in the small intestine. In
this study, we describe the initial characterization of the core
promoter region of this gene. Expression of chimeric promoter-reporter
constructs was supported in Caco-2 and HT-29 cells, and
DNase I footprint analysis revealed a large protein complex
within the core promoter region. Site-directed mutagenesis experiments
determined that elements within this region serve to either augment or
repress basal activity of the human pIgR promoter. Band
shift assays of overlapping oligonucleotides within the core promoter
identified eight distinct complexes; the abundance of most complexes
was enhanced in post-confluent cells. In summary, we report the
characterization of the human pIgR promoter and the
essential role that eight different nuclear complexes have in
controlling basal expression of this gene in Caco-2 cells.
upstream stimulatory factor; interferon response element; interferon response factor; adaptive immunity
