Abstract

The severity of intestinal disease associated with Cystic Fibrosis (CF) is variable in the patient population and this variability is partially conferred by the influence of modifier genes. Genome-wide association studies have identified SLC6A14, an electrogenic amino acid transporter, as a genetic modifier of CF-associated meconium ileus. The purpose of the current work was to determine the biological role of Slc6a14, by disrupting its expression in CF mice bearing the major mutation, F508del. We found that disruption of Slc6a14 worsened the intestinal fluid secretion defect characteristic of these mice. In vitro studies of mouse intestinal organoids revealed that exacerbation of the primary defect was associated with reduced arginine uptake across the apical membrane, with aberrant nitric oxide and cyclic GMP mediated regulation of the major CF-causing mutant protein. Together, these studies highlight the role of this apical transporter in modifying cellular nitric oxide levels, residual function of the major CF mutant and potentially, its promise as a therapeutic target.

Data availability

All of the data is presented in the submitted figures (in the article file) and supplementary file

Article and author information

Author details

  1. Saumel Ahmadi

    Department of Physiology, University of Toronto, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  2. Sunny Xia

    Department of Physiology, University of Toronto, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  3. Yu-Sheng Wu

    Department of Physiology, University of Toronto, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  4. Michelle Di Paola

    Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  5. Randolph Kissoon

    Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  6. Catherine Luk

    Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  7. Fan Lin

    Department of Molecular Genetics, University of Toronto, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  8. Kai Du

    Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  9. Johanna Rommens

    Department of Molecular Genetics, University of Toronto, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
  10. Christine Bear

    Department of Physiology, University of Toronto, Toronto, Canada
    For correspondence
    bear@sickkids.ca
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7063-3418

Funding

Canadian Institutes of Health Research (CIHR MOP-97954,CIHR GPG-102171)

  • Fan Lin

Cystic Fibrosis Canada (CFC-1)

  • Christine Bear

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: SickKids Animal Approval: #1000037433

Copyright

© 2018, Ahmadi et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 3,323
    views
  • 373
    downloads
  • 25
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Saumel Ahmadi
  2. Sunny Xia
  3. Yu-Sheng Wu
  4. Michelle Di Paola
  5. Randolph Kissoon
  6. Catherine Luk
  7. Fan Lin
  8. Kai Du
  9. Johanna Rommens
  10. Christine Bear
(2018)
SLC6A14, an amino acid transporter, modifies the primary CF defect in fluid secretion
eLife 7:e37963.
https://doi.org/10.7554/eLife.37963

Share this article

https://doi.org/10.7554/eLife.37963

Further reading

    1. Chromosomes and Gene Expression
    2. Genetics and Genomics
    Hasiba Asma, Ellen Tieke ... Marc S Halfon
    Tools and Resources

    Annotation of newly sequenced genomes frequently includes genes, but rarely covers important non-coding genomic features such as the cis-regulatory modules—e.g., enhancers and silencers—that regulate gene expression. Here, we begin to remedy this situation by developing a workflow for rapid initial annotation of insect regulatory sequences, and provide a searchable database resource with enhancer predictions for 33 genomes. Using our previously developed SCRMshaw computational enhancer prediction method, we predict over 2.8 million regulatory sequences along with the tissues where they are expected to be active, in a set of insect species ranging over 360 million years of evolution. Extensive analysis and validation of the data provides several lines of evidence suggesting that we achieve a high true-positive rate for enhancer prediction. One, we show that our predictions target specific loci, rather than random genomic locations. Two, we predict enhancers in orthologous loci across a diverged set of species to a significantly higher degree than random expectation would allow. Three, we demonstrate that our predictions are highly enriched for regions of accessible chromatin. Four, we achieve a validation rate in excess of 70% using in vivo reporter gene assays. As we continue to annotate both new tissues and new species, our regulatory annotation resource will provide a rich source of data for the research community and will have utility for both small-scale (single gene, single species) and large-scale (many genes, many species) studies of gene regulation. In particular, the ability to search for functionally related regulatory elements in orthologous loci should greatly facilitate studies of enhancer evolution even among distantly related species.

    1. Epidemiology and Global Health
    2. Genetics and Genomics
    Tianyu Zhao, Hui Li ... Li Chen
    Research Article

    Alzheimer’s disease (AD) is a complex degenerative disease of the central nervous system, and elucidating its pathogenesis remains challenging. In this study, we used the inverse-variance weighted (IVW) model as the major analysis method to perform hypothesis-free Mendelian randomization (MR) analysis on the data from MRC IEU OpenGWAS (18,097 exposure traits and 16 AD outcome traits), and conducted sensitivity analysis with six models, to assess the robustness of the IVW results, to identify various classes of risk or protective factors for AD, early-onset AD, and late-onset AD. We generated 400,274 data entries in total, among which the major analysis method of the IVW model consists of 73,129 records with 4840 exposure traits, which fall into 10 categories: Disease, Medical laboratory science, Imaging, Anthropometric, Treatment, Molecular trait, Gut microbiota, Past history, Family history, and Lifestyle trait. More importantly, a freely accessed online platform called MRAD (https://gwasmrad.com/mrad/) has been developed using the Shiny package with MR analysis results. Additionally, novel potential AD therapeutic targets (CD33, TBCA, VPS29, GNAI3, PSME1) are identified, among which CD33 was positively associated with the main outcome traits of AD, as well as with both EOAD and LOAD. TBCA and VPS29 were negatively associated with the main outcome traits of AD, as well as with both EOAD and LOAD. GNAI3 and PSME1 were negatively associated with the main outcome traits of AD, as well as with LOAD, but had no significant causal association with EOAD. The findings of our research advance our understanding of the etiology of AD.