Faculty Opinions recommendation of Global analysis of the fungal microbiome in cystic fibrosis patients reveals loss of function of the transcriptional repressor nrg1 as a mechanism of pathogen adaptation.

Cystic fibrosis (CF) is a lifelong disorder affecting 1 in 3500 live births worldwide. It is a monogenetic autosomal recessive disease caused by loss-of-function mutations in the gene encoding the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR), the impairment of which leads to ionic disequilibria in exocrine organs. This translates into a chronic multisystemic disease characterized by airway obstruction, respiratory infections, and pancreatic insufficiency as well as hepatobiliary and gastrointestinal dysfunction. Molecular characterization of the mutational heterogeneity of CFTR (affected by more than 2000 variants) improved the understanding and management of CF. However, these CFTR variants are linked to different clinical manifestations and phenotypes, and they affect response to treatments. Expanding evidence suggests that multisystemic disease affects CF pathology via impairing either CFTR or proteins regulated by CFTR. Thus, altering the expression of miRNAs in vivo could constitute an appealing strategy for developing new CF therapies. In this review, we will first describe the pathophysiology and clinical management of CF. Then, we will summarize the current knowledge on altered miRNAs in CF patients, with a focus on the miRNAs involved in the deregulation of CFTR and in the modulation of inflammation. We will highlight recent findings on the potential utility of measuring circulating miRNAs in CF as diagnostic, prognostic, and predictive biomarkers. Finally, we will provide an overview on potential miRNA-based therapeutic approaches.

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Knockdown of long noncoding RNA AC245100.4 inhibits the tumorigenesis of prostate cancer cells via the STAT3/NR4A3 axis

Epigenomics ◽

10.2217/epi-2021-0293 ◽

2021 ◽

Author(s):

Chi Liu ◽

Ping Lin ◽

Jiabin Zhao ◽

Hui Xie ◽

Rou Li ◽

...

Keyword(s):

Prostate Cancer ◽

Cancer Cells ◽

Rna Sequencing ◽

Long Noncoding Rna ◽

Noncoding Rna ◽

Transcriptional Repressor ◽

Sequencing Analysis ◽

Loss Of Function ◽

Prostate Cancer Cells ◽

Rna Immunoprecipitation

Aim: To explore the role and mechanism of long noncoding RNA AC245100.4 and NR4A3 in prostate cancer (PCa). Methods: RNA-sequencing analysis was used to detect the downstream genes of AC245100.4. A series of gain- and loss-of-function approaches were used to investigate the roles of AC245100.4 and NR4A3. RNA immunoprecipitation was performed to examine the interaction between AC245100.4 and STAT3. Results: AC245100.4 was significantly upregulated in PCa cells and tissues. Knockdown of AC21500.4 significantly inhibited the tumorigenesis of PCa cells. Mechanistically, AC245100.4 deregulated the transcription of NR4A3 via increasing p-STAT3, which acted as a transcriptional repressor of NR4A3. Conclusion: Knockdown of lncRNA AC245100.4 inhibits the tumorigenesis of PCa cells via the STAT3/ NR4A3 axis.

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Myeloid CFTR loss‐of‐function causes persistent neutrophilic inflammation in cystic fibrosis

Journal of Leukocyte Biology ◽

10.1002/jlb.3a0520-193rr ◽

2020 ◽

Vol 108 (6) ◽

pp. 1777-1785 ◽

Cited By ~ 1

Author(s):

Hang Pong Ng ◽

Scott Jennings ◽

Dianne Wellems ◽

Fei Sun ◽

Jie Xu ◽

...

Keyword(s):

Cystic Fibrosis ◽

Loss Of Function ◽

Neutrophilic Inflammation

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Characterizing diverse orthologues of the cystic fibrosis transmembrane conductance regulator protein for structural studies

Biochemical Society Transactions ◽

10.1042/bst20150081 ◽

2015 ◽

Vol 43 (5) ◽

pp. 894-900 ◽

Cited By ~ 2

Author(s):

Naomi L. Pollock ◽

Tracy L. Rimington ◽

Robert C. Ford

Keyword(s):

Cystic Fibrosis ◽

Structural Data ◽

Transmembrane Conductance Regulator ◽

Loss Of Function ◽

Transmembrane Conductance ◽

Functional Studies ◽

Regulator Protein ◽

Organ Systems ◽

Cftr Protein ◽

Cystic Fibrosis Transmembrane

As an ion channel, the cystic fibrosis transmembrane conductance regulator (CFTR) protein occupies a unique niche within the ABC family. Orthologues of CFTR are extant throughout the animal kingdom from sharks to platypods to sheep, where the osmoregulatory function of the protein has been applied to differing lifestyles and diverse organ systems. In humans, loss-of-function mutations to CFTR cause the disease cystic fibrosis, which is a significant health burden in populations of white European descent. Orthologue screening has proved fruitful in the pursuit of high-resolution structural data for several membrane proteins, and we have applied some of the princples developed in previous studies to the expression and purification of CFTR. We have overexpressed this protein, along with evolutionarily diverse orthologues, in Saccharomyces cerevisiae and developed a purification to isolate it in quantities sufficient for structural and functional studies.

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Defective organellar acidification as a cause of cystic fibrosis lung disease: reexamination of a recurring hypothesis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00018.2009 ◽

2009 ◽

Vol 296 (6) ◽

pp. L859-L867 ◽

Cited By ~ 35

Author(s):

Peter M. Haggie ◽

A. S. Verkman

Keyword(s):

Cystic Fibrosis ◽

Epithelial Cells ◽

Lung Disease ◽

Alveolar Macrophages ◽

Chloride Channels ◽

Loss Of Function ◽

Cellular Mechanisms ◽

Sodium Efflux ◽

Cystic Fibrosis Lung Disease ◽

Respiratory Epithelial

The cellular mechanisms by which loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel produce cystic fibrosis (CF) lung disease remain uncertain. Defective organellar function has been proposed as an important determinant in the pathogenesis of CF lung disease. According to one hypothesis, reduced CFTR chloride conductance in organelles in CF impairs their acidification by preventing chloride entry into the organelle lumen, which is needed to balance the positive charge produced by proton entry. According to a different hypothesis, CFTR mutation hyperacidifies organelles by an indirect mechanism involving unregulated sodium efflux through epithelial sodium channels. There are reports of defective Golgi, endosomal and lysosomal acidification in CF epithelial cells, defective phagolysosomal acidification in CF alveolar macrophages, and organellar hyperacidification in CF respiratory epithelial cells. The common theme relating too high or low organellar pH to cellular dysfunction and CF pathogenesis is impaired functioning of organellar enzymes, such as those involved in ceramide metabolism and protein processing in epithelial cells and antimicrobial activity in alveolar macrophages. We review here the evidence for defective organellar acidification in CF. Significant technical and conceptual concerns are discussed regarding the validity of data showing too high/low organellar pH in CF cells, and rigorous measurements of organellar pH in CF cells are reviewed that fail to support defective organellar acidification in CF. Indeed, there is an expanding body of evidence supporting the involvement of non-CFTR chloride channels in organellar acidification. We conclude that biologically significant involvement of CFTR in organellar acidification is unlikely.

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Functional Characterization of a Partial Loss-of-Function Mutation of the Epithelial Sodium Channel (ENaC) Associated with Atypical Cystic Fibrosis

Cellular Physiology and Biochemistry ◽

10.1159/000272059 ◽

2010 ◽

Vol 25 (001) ◽

pp. 145-158 ◽

Cited By ~ 16

Author(s):

Regina Huber ◽

Bettina Krueger ◽

Alexei Diakov ◽

Judit Korbmacher ◽

Silke Haerteis ◽

...

Keyword(s):

Cystic Fibrosis ◽

Sodium Channel ◽

Functional Characterization ◽

Epithelial Sodium Channel ◽

Loss Of Function ◽

Partial Loss ◽

Epithelial Sodium Channel Enac

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Inhibition of a transcriptional repressor rescues hearing in a splicing factor–deficient mouse

Life Science Alliance ◽

10.26508/lsa.202000841 ◽

2020 ◽

Vol 3 (12) ◽

pp. e202000841

Author(s):

Yoko Nakano ◽

Susan Wiechert ◽

Bernd Fritzsch ◽

Botond Bánfi

Keyword(s):

Alternative Splicing ◽

Target Genes ◽

Transcriptional Repressor ◽

Dominant Negative ◽

Splicing Factor ◽

Loss Of Function ◽

Transgenic Expression ◽

Mechanosensory Hair Cells

In mechanosensory hair cells (HCs) of the ear, the transcriptional repressor REST is continuously inactivated by alternative splicing of its pre-mRNA. This mechanism of REST inactivation is crucial for hearing in humans and mice. Rest is one of many pre-mRNAs whose alternative splicing is regulated by the splicing factor SRRM4; Srrm4 loss-of-function mutation in mice (Srrm4bv/bv) causes deafness, balance defects, and degeneration of all HC types other than the outer HCs (OHCs). The specific splicing alterations that drive HC degeneration in Srrm4bv/bv mice are unknown, and the mechanism underlying SRRM4-independent survival of OHCs is undefined. Here, we show that transgenic expression of a dominant-negative REST fragment in Srrm4bv/bv mice is sufficient for long-term rescue of hearing, balancing, HCs, alternative splicing of Rest, and expression of REST target genes including the Srrm4 paralog Srrm3. We also show that in HCs, SRRM3 regulates many of the same exons as SRRM4; OHCs are unique among HCs in that they transiently down-regulate Rest transcription as they mature to express Srrm3 independently of SRRM4; and simultaneous SRRM4–SRRM3 deficiency causes complete HC loss by preventing inactivation of REST in all HCs. Thus, our data reveal that REST inactivation is the primary and essential role of SRRM4 in the ear, and that OHCs differ from other HCs in the SRRM4-independent expression of the functionally SRRM4-like splicing factor SRRM3.

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Efflux Unbalance in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01024-08 ◽

2009 ◽

Vol 53 (5) ◽

pp. 1987-1997 ◽

Cited By ~ 65

Author(s):

Lucie Vettoretti ◽

Patrick Plésiat ◽

Cédric Muller ◽

Farid El Garch ◽

Gilles Phan ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Natural Resistance ◽

Loss Of Function ◽

Multidrug Efflux ◽

Efflux System ◽

Lactam Antibiotic ◽

Rnd Transporter ◽

First Time ◽

Selection Of

ABSTRACT Retrospective analysis of 189 nonredundant strains of Pseudomonas aeruginosa sequentially recovered from the sputum samples of 46 cystic fibrosis (CF) patients over a 10-year period (1998 to 2007) revealed that 53 out of 189 (28%) samples were hypersusceptible to the β-lactam antibiotic ticarcillin (MIC ≤ 4 μg/ml) (phenotype dubbed Tichs). As evidenced by trans-complementation and gene inactivation experiments, the mutational upregulation of the efflux system MexXY was responsible for various degrees of resistance to aminoglycosides in a selection of 11 genotypically distinct strains (gentamicin MICs from 2 to 64 μg/ml). By demonstrating for the first time that the MexXY pump may evolve in CF strains, we found that a mutation leading to an F1018L change in the resistance-nodulation-cell division (RND) transporter MexY was able to increase pump-promoted resistance to aminoglycosides, cefepime, and fluoroquinolones twofold. The inactivation of the mexB gene (which codes for the RND transporter MexB) in the 11 selected strains showed that the Tichs phenotype was due to a mutational or functional loss of function of MexAB-OprM, the multidrug efflux system known to contribute to the natural resistance of P. aeruginosa to β-lactams (e.g., ticarcillin and aztreonam), fluoroquinolones, tetracycline, and novobiocin. Two of the selected strains synthesized abnormally low amounts of the MexB protein, and 3 of 11 strains expressed truncated MexB (n = 2) or MexA (n = 1) polypeptide as a result of mutations in the corresponding genes, while 7 of 11 strains produced wild-type though nonfunctional MexAB-OprM pumps at levels similar to or even higher than that of reference strain PAO1. Overall, our data indicate that while MexXY is necessary for P. aeruginosa to adapt to the hostile environment of the CF lung, the MexAB-OprM pump is dispensable and tends to be lost or inactivated in subpopulations of P. aeruginosa.

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