The role of Sp1 in IL-1beta and H. pylori-mediated regulation of H,K-ATPase gene transcription.
Helicobacter pylori infection of the gastric body induces transient hypochlorhydria and contributes to mucosal progression toward gastric carcinoma. Acid secretion is mediated by parietal cell H,K-ATPase, in which the catalytic alpha-subunit (HKalpha) promoter activity in transfected gastric epithelial [gastric adenocarcinoma (AGS)] cells is repressed by H. pylori through NF-kappaB p50 homodimer binding to the promoter. IL-1beta, an acid secretory inhibitor whose mucosal level is increased by H. pylori, upregulates HKalpha promoter activity in AGS cells. Because IL-1beta also activates NF-kappaB signaling, we investigated disparate HKalpha regulation by H. pylori and IL-1beta, testing the hypothesis that IL-1beta-induced HKalpha promoter activation is mediated by the transcription factor Sp1. DNase I footprinting revealed Sp1 binding to the HKalpha promoter at -56 to -39 bp. IL-1beta stimulated the activity of three HKalpha promoter constructs containing NF-kappaB and Sp1 sites transfected into AGS cells and also stimulated a construct containing only an Sp1 site. This stimulation was abrogated by mutating the HKalpha promoter Sp1 binding site. Gelshift assays showed that IL-1beta increased Sp1 but not p50 binding to cognate HKalpha probes and that Sp1 also interacts with an HKalpha NF-kappaB site when bound to its cognate HKalpha cis-response element. H. pylori did not augment Sp1 binding to an HKalpha Sp1 probe, and small interfering RNA-mediated knockdown of Sp1 expression abrogated IL-1beta-induced HKalpha promoter stimulation. We conclude that IL-1beta upregulates HKalpha gene transcription by inducing Sp1 binding to HKalpha Sp1 and NF-kappaB sites and that the H. pylori perturbation of HKalpha gene expression is independent of Sp1-mediated basal HKalpha transcription.
Saha
Arindam
A
Medical Univ. of South Carolina, Charleston, SC 29425, USA.
Hammond
Charles E
CE
Gooz
Monika
M
Smolka
Adam J
AJ
D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D017506:H(+)-K(+)-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D016480:Helicobacter pylori / Q000502:physiology*; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D011485:Protein Binding; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism*
D053583:Interleukin-1beta; D016328:NF-kappa B; D016329:Sp1 Transcription Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D017506:H(+)-K(+)-Exchanging ATPase
Am J Physiol Gastrointest Liver Physiol. 2007 Feb;292(2):G535-45
17023546
J Biol Chem. 1995 Aug 4;270(31):18637-42
7629193
Gut. 1997 Oct;41(4):442-51
9391240
Gastroenterology. 1997 Jul;113(1):15-24
9207257
FASEB J. 2004 Jan;18(1):218-20
14597566
Oncogene. 2005 Mar 31;24(14):2354-66
15735748
Cancer Res. 1992 Dec 15;52(24):6735-40
1458460
Am J Physiol Gastrointest Liver Physiol. 2008 Mar;294(3):G795-807
18202112
J Biol Chem. 1989 Jul 5;264(19):11381-6
2544591
Nat Immunol. 2004 Nov;5(11):1166-74
15489856
Am J Physiol Renal Physiol. 2005 Oct;289(4):F808-15
15798085
Oncogene. 2007 Nov 15;26(52):7324-32
17533369
Oncogene. 1998 Apr 23;16(16):2095-102
9572490
Am J Physiol. 1996 Dec;271(6 Pt 1):G1104-13
8997255
FEBS J. 2007 Oct;274(20):5250-62
17892496
J Biol Chem. 2003 Aug 29;278(35):32552-60
12807870
Mol Cell Biol. 1998 Mar;18(3):1266-74
9488441
FEBS Lett. 1994 Feb 28;340(1-2):117-20
8119393
J Biol Chem. 2001 Dec 21;276(51):48127-34
11604402
Int J Clin Lab Res. 1996;26(3):207-10
8905454
Cell Signal. 2008 Jan;20(1):60-72
17889508
Am J Physiol Cell Physiol. 2000 Apr;278(4):C697-708
10751319
Nature. 2000 Mar 23;404(6776):398-402
10746728
Am J Physiol Gastrointest Liver Physiol. 2007 Apr;292(4):G1055-61
17204545
Am J Physiol. 1998 Nov;275(5):G1094-105
9815040
Cancer Res. 1983 Apr;43(4):1703-9
6831414
J Gastroenterol. 1999;34 Suppl 11:10-7
10616759
J Biol Chem. 2001 Dec 7;276(49):46436-44
11564730
Proc Natl Acad Sci U S A. 2000 Jul 18;97(15):8542-7
10900013
Lab Invest. 1995 Dec;73(6):760-70
8558837
Biochem Biophys Res Commun. 2001 Jun 8;284(2):443-9
11394899
Exp Cell Res. 2007 Apr 1;313(6):1069-79
17289023
Am J Physiol. 1991 Oct;261(4 Pt 1):G559-64
1681735
Gastroenterology. 1997 Oct;113(4):1099-109
9322504
Infect Immun. 1995 May;63(5):1681-87
7729872
J Clin Pathol. 1994 Oct;47(10):945-50
7962609
Am J Physiol Gastrointest Liver Physiol. 2000 Jun;278(6):G981-91
10859229
J Clin Pathol. 2006 Dec;59(12):1293-9
16644877