The role of STAT, AP-1, E-box and TIEG motifs in the regulation of hepcidin by IL-6 and BMP-9: lessons from human HAMP and murine Hamp1 and Hamp2 gene promoters.
Hepcidin, the principal regulator of the iron metabolism, is up-regulated in response to inflammatory stimuli, bone morphogenic proteins (BMPs) and iron excess. There are two murine hepcidin genes: hepcidin-1 (Hamp1) and hepcidin-2 (Hamp2). Hamp1 gene responds to both IL-6 and BMPs while Hamp2 responds to neither. We replaced the putative functional regulatory motifs of the Hamp1 promoter with the corresponding putative "non-functional" Hamp2 motifs and vice versa in reporter constructs. Conversion of the Hamp1 STAT site into the Hamp2 site reduced the basal level of reporter expression but did not affect IL-6 and BMP responsiveness; replacing Hamp2 site with the Hamp1 site only resulted in partial responsiveness. These data are in contrast to the role of the STAT site in the human hepcidin promoter which is important in both basal level and IL-6 inducible promoter activity. The murine AP1, E-box and TIEG motifs were found to neither influence the basal level of expression of Hamp1 and HAMP promoters nor play a critical role in the IL-6 and BMP-9 induced response. Our data suggest that the STAT site (nt -148 to -130) is important for the regulation of basal level expression of Hamp1 but there are additional regions that are responsible for the IL-6 and BMP-9 responsiveness within the Hamp1 promoter.
Truksa
Jaroslav
J
Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. truksa@scripps.edu
Lee
Pauline
P
Beutler
Ernest
E
D020816:Amino Acid Motifs; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D024721:E-Box Elements / Q000235:genetics; D005786:Gene Expression Regulation; D055427:Growth Differentiation Factor 2; D055412:Growth Differentiation Factors; D064451:Hepcidins; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D050791:STAT Transcription Factors / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; D019485:Bone Morphogenetic Proteins; C525887:GDF2 protein, human; C526108:Gdf2 protein, mouse; D055427:Growth Differentiation Factor 2; D055412:Growth Differentiation Factors; C578702:HAMP protein, human; C579599:Hamp protein, mouse; C474320:Hamp2 protein, mouse; D064451:Hepcidins; D015850:Interleukin-6; D050791:STAT Transcription Factors; D018808:Transcription Factor AP-1
Nucleic Acids Res. 1995 Dec 11;23(23):4907-12
8532536
J Hepatol. 2004 Jun;40(6):891-6
15158327
Proc Natl Acad Sci U S A. 2005 Feb 8;102(6):1906-10
15684062
Cell Metab. 2005 Dec;2(6):399-409
16330325
Nat Genet. 2006 May;38(5):531-9
16604073
Proc Natl Acad Sci U S A. 2006 Jul 5;103(27):10289-93
16801541
Annu Rev Nutr. 2006;26:323-42
16848710
Blood. 2006 Nov 1;108(9):3204-9
16835372
Blood. 2006 Dec 15;108(13):4237-45
16902156
Blood. 2007 Jan 1;109(1):353-8
16946298
Gastroenterology. 2007 Jan;132(1):294-300
17241879
Mol Biol Cell. 2007 Jul;18(7):2569-78
17475779
Br J Haematol. 2007 Oct;139(1):138-47
17854319
J Biol Chem. 2000 Jun 16;275(24):17937-45
10849432
Oncogene. 2002 Aug 22;21(37):5783-90
12173049
J Cell Biochem. 2002;87(2):233-41
12244575
J Clin Invest. 2002 Oct;110(7):1037-44
12370282
J Biol Chem. 2002 Oct 25;277(43):41163-70
12183449
Blood. 2004 Apr 1;103(7):2816-21
14604961
Science. 2004 Dec 17;306(5704):2090-3
15514116