Biophysical models reveal the relative importance of transporter proteins and impermeant anions in chloride homeostasis

  1. Kira Michaela Düsterwald
  2. Christopher Brian Currin
  3. Richard Joseph Burman
  4. Colin J Akerman
  5. Alan R Kay
  6. Joseph Valentino Raimondo  Is a corresponding author
  1. University of Cape Town, South Africa
  2. University of Oxford, United Kingdom
  3. University of Iowa, United States

Abstract

Fast synaptic inhibition in the nervous system depends on the transmembrane flux of Cl- ions based on the neuronal Cl- driving force. Established theories regarding the determinants of Cl- driving force have recently been questioned. Here we present biophysical models of Cl- homeostasis using the pump-leak model. Using numerical and novel analytic solutions, we demonstrate that the Na+/K+-ATPase, ion conductances, impermeant anions, electrodiffusion, water fluxes and cation-chloride cotransporters (CCCs) play roles in setting the Cl- driving force. Our models, together with experimental validation, show that while impermeant anions can contribute to setting [Cl-]i in neurons, they have a negligible effect on the driving force for Cl- locally and cell-wide. In contrast, we demonstrate that CCCs are well-suited for modulating Cl- driving force and hence inhibitory signalling in neurons. Our findings reconcile recent experimental findings and provide a framework for understanding the interplay of different chloride regulatory processes in neurons.

Data availability

Code data is available on GitHub. Experimental data in the form of data spreadsheets has been included, and full experimental data is available on Dryad.

The following data sets were generated

Article and author information

Author details

  1. Kira Michaela Düsterwald

    Department of Human Biology, University of Cape Town, Cape Town, South Africa
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3217-5326
  2. Christopher Brian Currin

    Department of Human Biology, University of Cape Town, Cape Town, South Africa
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4809-5059
  3. Richard Joseph Burman

    Department of Human Biology, University of Cape Town, Cape Town, South Africa
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3107-7871
  4. Colin J Akerman

    Department of Pharmacology, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6844-4984
  5. Alan R Kay

    Department of Biology, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2820-6188
  6. Joseph Valentino Raimondo

    Department of Human Biology, University of Cape Town, Cape Town, South Africa
    For correspondence
    joseph.raimondo@uct.ac.za
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8266-3128

Funding

Mandela Rhodes Foundation

  • Kira Michaela Düsterwald
  • Richard Joseph Burman

DAAD-NRF

  • Christopher Brian Currin

Newton Fund

  • Joseph Valentino Raimondo

Blue Brain Project

  • Joseph Valentino Raimondo

H2020 European Research Council (ERC Grant Agreement 617670)

  • Colin J Akerman

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

Reviewing Editor

  1. Kenton Jon Swartz, National Institute of Neurological Disorders and Stroke, National Institutes of Health, United States

Ethics

Animal experimentation: No experiments were performed on animals prior to humane killing using cervical dislocation at P7, every effort was made to minimise stress prior to killing. The use of rats in the UK (furosemide experiment) were in accordance with regulations from the United Kingdom Home Office Animals (Scientific Procedures) Act. Use of mice (electroporation experiment) at the University of Cape Town was in accordance with South African national guidelines (South African National Standard: The care and use of animals for scientific purposes, 2008) and was approved by the University of Cape Town Animal Ethics Committee protocol no 014/035.

Version history

  1. Received: June 26, 2018
  2. Accepted: September 24, 2018
  3. Accepted Manuscript published: September 27, 2018 (version 1)
  4. Version of Record published: October 24, 2018 (version 2)
  5. Version of Record updated: October 31, 2018 (version 3)

Copyright

© 2018, Düsterwald 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

  • 2,323
    views
  • 377
    downloads
  • 31
    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. Kira Michaela Düsterwald
  2. Christopher Brian Currin
  3. Richard Joseph Burman
  4. Colin J Akerman
  5. Alan R Kay
  6. Joseph Valentino Raimondo
(2018)
Biophysical models reveal the relative importance of transporter proteins and impermeant anions in chloride homeostasis
eLife 7:e39575.
https://doi.org/10.7554/eLife.39575

Share this article

https://doi.org/10.7554/eLife.39575

Further reading

    1. Computational and Systems Biology
    Skander Kazdaghli, Iordanis Kerenidis ... Philip Teare
    Research Article

    Imputing data is a critical issue for machine learning practitioners, including in the life sciences domain, where missing clinical data is a typical situation and the reliability of the imputation is of great importance. Currently, there is no canonical approach for imputation of clinical data and widely used algorithms introduce variance in the downstream classification. Here we propose novel imputation methods based on determinantal point processes (DPP) that enhance popular techniques such as the multivariate imputation by chained equations and MissForest. Their advantages are twofold: improving the quality of the imputed data demonstrated by increased accuracy of the downstream classification and providing deterministic and reliable imputations that remove the variance from the classification results. We experimentally demonstrate the advantages of our methods by performing extensive imputations on synthetic and real clinical data. We also perform quantum hardware experiments by applying the quantum circuits for DPP sampling since such quantum algorithms provide a computational advantage with respect to classical ones. We demonstrate competitive results with up to 10 qubits for small-scale imputation tasks on a state-of-the-art IBM quantum processor. Our classical and quantum methods improve the effectiveness and robustness of clinical data prediction modeling by providing better and more reliable data imputations. These improvements can add significant value in settings demanding high precision, such as in pharmaceutical drug trials where our approach can provide higher confidence in the predictions made.

    1. Computational and Systems Biology
    Antony M Jose
    Research Article

    Interacting molecules create regulatory architectures that can persist despite turnover of molecules. Although epigenetic changes occur within the context of such architectures, there is limited understanding of how they can influence the heritability of changes. Here, I develop criteria for the heritability of regulatory architectures and use quantitative simulations of interacting regulators parsed as entities, their sensors, and the sensed properties to analyze how architectures influence heritable epigenetic changes. Information contained in regulatory architectures grows rapidly with the number of interacting molecules and its transmission requires positive feedback loops. While these architectures can recover after many epigenetic perturbations, some resulting changes can become permanently heritable. Architectures that are otherwise unstable can become heritable through periodic interactions with external regulators, which suggests that mortal somatic lineages with cells that reproducibly interact with the immortal germ lineage could make a wider variety of architectures heritable. Differential inhibition of the positive feedback loops that transmit regulatory architectures across generations can explain the gene-specific differences in heritable RNA silencing observed in the nematode Caenorhabditis elegans. More broadly, these results provide a foundation for analyzing the inheritance of epigenetic changes within the context of the regulatory architectures implemented using diverse molecules in different living systems.