Transforming Growth Factor-β and Interleukin-1β Signaling Pathways Converge on the Chemokine CCL20 Promoter.
CCL20 is the only chemokine ligand for the chemokine receptor CCR6, which is expressed by the critical antigen presenting cells, dendritic cells. Increased expression of CCL20 is likely involved in the increased recruitment of dendritic cells observed in fibroinflammatory diseases such as chronic obstructive pulmonary disease (COPD). CCL20 expression is increased by the proinflammatory cytokine IL-1β. We have determined that IL-1β-dependent CCL20 expression is also dependent on the multifunctional cytokine TGF-β. TGF-β is expressed in a latent form that must be activated to function, and activation is achieved through binding to the integrin αvβ8 (itgb8). Here we confirm correlative increases in αvβ8 and IL-1β with CCL20 protein in lung parenchymal lysates of a large cohort of COPD patients. How IL-1β- and αvβ8-mediated TGF-β activation conspire to increase fibroblast CCL20 expression remains unknown, because these pathways have not been shown to directly interact. We evaluate the 5'-flanking region of CCL20 to determine that IL-1β-driven CCL20 expression is dependent on αvβ8-mediated activation of TGF-β. We identify a TGF-β-responsive element (i.e. SMAD) located on an upstream enhancer of the human CCL20 promoter required for efficient IL-1β-dependent CCL20 expression. By chromatin immunoprecipitation, this upstream enhancer complexes with the p50 subunit of NF-κB on a NF-κB-binding element close to the transcriptional start site of CCL20. These interactions are confirmed by electromobility shift assays in nuclear extracts from human lung fibroblasts. These data define a mechanism by which αvβ8-dependent activation of TGF-β regulates IL-1β-dependent CCL20 expression in COPD.
From the Departments of Pathology.
Oliver J
OJ
Brand
From the Departments of Pathology.
Sangeeta
S
Somanath
From the Departments of Pathology.
Catherine
C
Moermans
From the Departments of Pathology.
Haruhiko
H
Yanagisawa
From the Departments of Pathology.
Mitsuo
M
Hashimoto
From the Departments of Pathology.
Stephanie
S
Cambier
From the Departments of Pathology.
Jennifer
J
Markovics
From the Departments of Pathology.
Andrew J
AJ
Bondesson
Surgery, University of California, San Francisco, California 94110.
Arthur
A
Hill
Surgery, University of California, San Francisco, California 94110.
David
D
Jablons
Medicine, and.
Paul
P
Wolters
Anesthesia and Perioperative Care.
Jianlong
J
Lou
Anesthesia and Perioperative Care.
James D
JD
Marks
Medicine, and.
Jody L
JL
Baron
From the Departments of Pathology, stephen.nishimura@ucsf.edu.
Stephen L
SL
Nishimura
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D054418:Chemokine CCL20 / Q000235:genetics*; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D053583:Interleukin-1beta / Q000276:immunology*; D008168:Lung / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000276:immunology; D020218:Response Elements; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000276:immunology*
C108355:CCL20 protein, human; D054418:Chemokine CCL20; D053583:Interleukin-1beta; D016328:NF-kappa B; D016212:Transforming Growth Factor beta
TGF-β; chemokine; inflammation; integrin; transcription