Loss of CFTR results in reduction of histone deacetylase 2 in airway epithelial cells.
ABSTRACT 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.
Article: Oxidative stress reduces histone deacetylase 2 activity and enhances IL-8 gene expression: role of tyrosine nitration.[show abstract] [hide abstract]
ABSTRACT: Oxidative stress is a characteristic of chronic inflammatory diseases. The reactive oxygen intermediate hydrogen peroxide (H(2)O(2)) is an important signaling molecule that modulates gene expression. We have demonstrated that H(2)O(2) significantly enhanced cytokine production in BEAS-2B cells, with a maximal effect at 4h. This did not result from enhanced NF-kappaB activation, but through decreased activity of histone deacetylase (HDAC)2. This results in increased inflammatory gene expression following acetylation of specific histone residues. Decreased HDAC2 activity was associated with tyrosine nitration status. Peroxynitrite and SIN-1, a peroxynitrite generator, were also able to reduce HDAC2 activity via tyrosine nitration. Our data suggest that oxidative stress contributes to worsening inflammation via reduction of HDAC2 activity through HDAC2 nitration. This novel mechanism of inflammation may be important in increasing the severity and chronicity of inflammatory diseases.Biochemical and Biophysical Research Communications 03/2004; 315(1):240-5. · 2.48 Impact Factor
Article: The histone deacetylase inhibitor valproic acid selectively induces proteasomal degradation of HDAC2.[show abstract] [hide abstract]
ABSTRACT: Histone-modifying enzymes play essential roles in physiological and aberrant gene regulation. Since histone deacetylases (HDACs) are promising targets of cancer therapy, it is important to understand the mechanisms of HDAC regulation. Selective modulators of HDAC isoenzymes could serve as efficient and well-tolerated drugs. We show that HDAC2 undergoes basal turnover by the ubiquitin-proteasome pathway. Valproic acid (VPA), in addition to selectively inhibiting the catalytic activity of class I HDACs, induces proteasomal degradation of HDAC2, in contrast to other inhibitors such as trichostatin A (TSA). Basal and VPA-induced HDAC2 turnover critically depend on the E2 ubiquitin conjugase Ubc8 and the E3 ubiquitin ligase RLIM. Ubc8 gene expression is induced by both VPA and TSA, whereas only TSA simultaneously reduces RLIM protein levels and therefore fails to induce HDAC2 degradation. Thus, poly-ubiquitination and proteasomal degradation provide an isoenzyme-selective mechanism for downregulation of HDAC2.The EMBO Journal 08/2003; 22(13):3411-20. · 9.20 Impact Factor
Article: Distinct pattern of immune cell population in the lung of human fetuses with cystic fibrosis.[show abstract] [hide abstract]
ABSTRACT: Airway inflammation and infection are early events in cystic fibrosis (CF) pathogenesis. The existence of an imbalance in the immune cell population of the CF fetal airway before infection remains completely unknown. The aim of this study was to determine whether early signs of inflammation are observed in CF airways during human fetal development. Tracheas and lungs were collected from 21 CF and 16 non-CF fetuses. In tissue sections, the numbers of neutrophils, mast cells, macrophages, and B and T lymphocytes were quantitatively analyzed by means of image cytometry. The presence of IL-4, IL-6, IL-8, IL-10, RANTES, IFN-gamma, TNF-alpha, and NF kappa B and its inhibitor I kappa B-alpha was qualitatively evaluated by immunofluorescent staining. During fetal airway development, epithelial and glandular differentiation, as well as the distribution of inflammatory markers, was similar in CF and non-CF tissues. Significant differences between CF and non-CF fetal airways were observed only in the numbers of mast cells and macrophages. In the CF trachea, the mast cell number increased slowly but continuously, whereas in the non-CF trachea this number rapidly reached a plateau. In the CF lung, the macrophage number increased with time, whereas in the non-CF lung it decreased. Although no intrinsic inflammation was demonstrated, we observed a distinct appearance of mast cells and macrophages in CF airways in comparison with non-CF airways during fetal development. These 2 cell populations were greater in CF airways at a late stage of fetal development, suggesting their possible involvement in the early onset of inflammation in CF infants.Journal of Allergy and Clinical Immunology 11/2001; 108(4):524-9. · 11.00 Impact Factor