Loss of CFTR results in reduction of histone deacetylase 2 in airway epithelial cells.
Inflammatory cytokines, particularly the neutrophil chemoattractant IL-8, are elevated in the cystic fibrosis (CF) airway, even in the absence of detectable infection. The transcriptional regulation of many inflammatory genes, including IL8 (CXCL8), involves chromatin remodeling through histone acetylation. NF-kappaB is known to facilitate histone acetylation of IL8 and other proinflammatory gene promoters, but we find that increased NF-kappaB activation cannot explain the elevated IL8 expression and promoter acetylation seen in CFTR-deficient cells. Recognized components of the NF-kappaB-coactivator complex, acetyltransferase CBP, p300, and the histone deacetylase HDAC1, are unchanged by CFTR activity. However, we find that the histone acetyltransferase (HAT)/HDAC balance is sensitive to CFTR function, as cells with reduced or absent CFTR function have decreased HDAC2 protein, resulting in hyperacetylation of the IL8 promoter and increased IL8 transcription. Reduced HDAC2 and HDAC2 activity, but not HDAC2 mRNA, is observed in cells deficient in CFTR. Suppressing HDAC2 expression with HDAC2 short hairpin RNA (shRNA) results in increased IL8 expression and promoter acetylation comparable with CFTR-deficient cells. Treating CFTR-deficient cells with N-acetyl-cysteine (NAC) increases HDAC2 expression to near control levels. Our data suggest that there is an intrinsic alteration in the HAT/HDAC balance in cells lacking CFTR function in vitro and in native CF tissue and that oxidative stress is likely contributing to this alteration. This mechanism, found in other inflammatory airway diseases, provides an explanation for the apparent dysregulation of inflammatory mediators seen in the CF airway, as reduced histone deacetylation would potentially influence many genes.
Bartling
Toni R
TR
Department of Genetics, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio, USA.
Drumm
Mitchell L
ML
D000107:Acetylation / Q000187:drug effects; D000111:Acetylcysteine / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003550:Cystic Fibrosis / Q000201:enzymology / Q000473:pathology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000172:deficiency* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D055785:Gene Knockdown Techniques; D056464:Histone Deacetylase 2; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D012137:Respiratory System / Q000166:cytology*; D050880:p300-CBP Transcription Factors / Q000378:metabolism
D016209:Interleukin-8; D016328:NF-kappa B; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D050880:p300-CBP Transcription Factors; D056464:Histone Deacetylase 2; D006655:Histone Deacetylases; D000111:Acetylcysteine