The heat shock response inhibits RANTES gene expression in cultured human lung epithelium.
The chemokine RANTES is thought to be involved in the pathophysiology of inflammation-associated acute lung injury. Although much is known regarding signals that induce RANTES gene expression, relatively few data exist regarding signals that inhibit RANTES gene expression. The heat shock response, a highly conserved cellular defense mechanism, has been demonstrated to inhibit a variety of lung proinflammatory responses. We tested the hypothesis that induction of the heat shock response inhibits RANTES gene expression. Treatment of A549 cells with TNF-alpha induced RANTES gene expression in a concentration-dependent manner. Induction of the heat shock response inhibited subsequent TNF-alpha-mediated RANTES mRNA expression and secretion of immunoreactive RANTES. Transient transfection assays involving a RANTES promoter-luciferase reporter plasmid demonstrated that the heat shock response inhibited TNF-alpha-mediated activation of the RANTES promoter. Inhibition of NF-kappaB nuclear translocation with isohelenin inhibited TNF-alpha-mediated RANTES mRNA expression, indicating that RANTES gene expression is NF-kappaB dependent in A549 cells. Induction of the heat shock response inhibited degradation of the NF-kappaB inhibitory protein, I-kappaBalpha but did not significantly inhibit phosphorylation of I-kappaBalpha. We conclude that the heat shock response inhibits RANTES gene expression by a mechanism involving inhibition of NF-kappaB nuclear translocation and subsequent inhibition of RANTES promoter activation. The mechanism by which the heat shock response inhibits NF-kappaB nuclear translocation involves stabilization of I-kappaBalpha, without significantly affecting phosphorylation of I-kappaBalpha.
Ayad
O
O
Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Stark
J M
JM
Fiedler
M M
MM
Menendez
I Y
IY
Ryan
M A
MA
Wong
H R
HR
D000230:Adenocarcinoma; D018946:Chemokine CCL5 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D018869:Heat-Shock Response / Q000235:genetics*; D006801:Humans; D020672:I-kappa B Proteins; D008168:Lung / Q000378:metabolism*; D008175:Lung Neoplasms; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D018946:Chemokine CCL5; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha