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Multiple Mechanisms Influence Regulation of the Cystic Fibrosis Transmembrane Conductance Regulator Gene Promoter

Published on Sep 1, 2010in American Journal of Respiratory Cell and Molecular Biology4.34
路 DOI :10.1165/rcmb.2009-0149OC
Marzena Anna Lewandowska13
Estimated H-index: 13
(NU: Northwestern University),
Fabricio F. Costa24
Estimated H-index: 24
(NU: Northwestern University)
+ 3 AuthorsAnn Harris24
Estimated H-index: 24
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) gene is driven by a promoter that cannot alone account for the temporal and tissue-specific regulation of the gene. This has led to the search for additional regulatory elements that cooperate with the basal promoter to achieve coordinated expression. We previously identified two alternative upstream exons of the gene that were mutually exclusive of the first exon, and one of which showed temporal regulation in the human and sheep lung. We now demonstrate that this alternative splice product generates a stable protein, which initiates translation at an ATG in exon 4, and thus lacks the N terminus of CFTR. The other splice variant inhibits translation of the protein. In a search for the promoter used by the upstream exons, we identified a novel element that contributes to the activity of the basal CFTR promoter in airway epithelial cells, but does not function independently. Finally, we demonstrate that, in primary airway cells, skin fibroblasts, and both airway and intestinal cell lines, the CFTR promoter is unmethylated, irrespective of CFTR expression status. Thus, methylation is not the main cause of inactivation of CFTR transcription.
  • References (46)
  • Citations (15)
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References46
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#1Christopher J. Ott (NU: Northwestern University)H-Index: 17
#2Magdalena I. Suszko (NU: Northwestern University)H-Index: 5
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#1Jon A. Oyer (OHSU: Oregon Health & Science University)H-Index: 2
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Background Aberrant epigenetic silencing plays a major role in cancer formation by inactivating tumor suppressor genes. While the endpoints of aberrant silencing are known, i.e., promoter region DNA methylation and altered histone modifications, the triggers of silencing are not known. We used the tet-off system to test the hypothesis that a transient reduction in gene expression will sensitize a promoter to undergo epigenetic silencing. Methodology/Principal Findings The tet responsive promoter...
34 CitationsSource
#1Anabela S. Ramalho (Instituto Nacional de Sa煤de Dr. Ricardo Jorge)H-Index: 12
#2Marzena Anna Lewandowska (NU: Northwestern University)H-Index: 13
Last. Margarida D. Amaral (Instituto Nacional de Sa煤de Dr. Ricardo Jorge)H-Index: 35
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Background/Aims: Mutations in the CFTR gene cause Cystic Fibrosis (CF) the most common life-threaten- ing autosomal recessive disease affecting Cauca- sians. We identified a CFTR mutation (c.120del23) abolishing the normal translation initiation codon, which occurs in two Portuguese CF patients. This study aims at functionally characterizing the effect of this novel mutation. Methods: RNA and protein tech- niques were applied to both native tissues from CF patients and recombinant cells expressi...
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#1Rafal BartoszewskiH-Index: 20
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Abstract The unfolded protein response (UPR) aids cellular recovery by increasing the capacity and decreasing the protein load of the endoplasmic reticulum (ER). Although the main pathways of the UPR are known, the mechanisms of UPR-associated transcriptional repression have not been explored in mammalian cells. Previous studies indicate that endogenous cystic fibrosis transmembrane conductance regulator (CFTR) mRNA levels and protein maturation efficiency decrease when the UPR is activated. In ...
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Regulatory elements that lie outside the basal promoter of a gene may be revealed by local changes in chromatin structure and histone modifications. The promoter of the CFTR (cystic fibrosis transmembrane conductance regulator) gene is not responsible for its complex pattern of expression. To identify important regulatory elements for CFTR we have previously mapped DHS (DNase I-hypersensitive sites) across 400聽kb spanning the locus. Of particular interest were two DHS that flank the CFTR gene, u...
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To gain insight into the function of DNA methylation at cis-regulatory regions and its impact on gene expression, we measured methylation, RNA polymerase occupancy and histone modifications at 16,000 promoters in primary human somatic and germline cells. We find CpG-poor promoters hypermethylated in somatic cells, which does not preclude their activity. This methylation is present in male gametes and results in evolutionary loss of CpG dinucleotides, as measured by divergence between humans and ...
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