Abstract

ARL13B is a regulatory GTPase highly enriched in cilia. Complete loss of Arl13b disrupts cilia architecture, protein trafficking and Sonic hedgehog signaling. To determine whether ARL13B is required within cilia, we knocked in a cilia-excluded variant of ARL13B (V358A) and showed it retains all known biochemical function. We found that ARL13BV358A protein was expressed but could not be detected in cilia, even when retrograde ciliary transport was blocked. We showed Arl13bV358A/V358A mice are viable and fertile with normal Shh signal transduction. However, in contrast to wild type cilia, Arl13bV358A/V358A cells displayed short cilia and lacked ciliary ARL3 and INPP5E. These data indicate that ARL13B's role within cilia can be uncoupled from its function outside of cilia. Furthermore, these data imply that the cilia defects upon complete absence of ARL13B do not underlie the alterations in Shh transduction, which is unexpected given the requirement of cilia for Shh transduction.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files.

Article and author information

Author details

  1. Eduardo D Gigante

    Human Genetics, Emory University, Atlanta, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Megan R Taylor

    Human Genetics, Emory University, Atlanta, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Anna A Ivanova

    Biochemistry, Emory University, Atlanta, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Richard A Kahn

    Biochemistry, Emory University, Atlanta, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Tamara Caspary

    Human Genetics, Emory University, Atlanta, United States
    For correspondence
    tcaspar@emory.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6579-7589

Funding

NINDS (R01NS090029)

  • Tamara Caspary

NIGMS (R35GM122549)

  • Tamara Caspary

NIGMS (R35GM122568)

  • Richard A Kahn

NINDS (T32NS096050)

  • Eduardo D Gigante

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

Ethics

Animal experimentation: All mice were cared for in accordance with NIH guidelines and Emory's Institutional Animal Care and Use Committee (IACUC) under protocols DAR-2003545-072919N and PROTO201700587.

Reviewing Editor

  1. Jeremy F Reiter, University of California, San Francisco, United States

Publication history

  1. Received: July 23, 2019
  2. Accepted: February 25, 2020
  3. Accepted Manuscript published: March 4, 2020 (version 1)
  4. Version of Record published: March 16, 2020 (version 2)

Copyright

© 2020, Gigante 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

  • 5,187
    Page views
  • 695
    Downloads
  • 33
    Citations

Article citation count generated by polling the highest count across the following sources: Scopus, Crossref, PubMed Central.

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. Eduardo D Gigante
  2. Megan R Taylor
  3. Anna A Ivanova
  4. Richard A Kahn
  5. Tamara Caspary
(2020)
ARL13B regulates Sonic Hedgehog signaling from outside primary cilia
eLife 9:e50434.
https://doi.org/10.7554/eLife.50434

Further reading

    1. Cell Biology
    Brett C Baggett, Kevin R Murphy ... Gideon Koren
    Research Article Updated

    Progressive tissue remodeling after myocardial infarction (MI) promotes cardiac arrhythmias. This process is well studied in young animals, but little is known about pro-arrhythmic changes in aged animals. Senescent cells accumulate with age and accelerate age-associated diseases. Senescent cells interfere with cardiac function and outcome post-MI with age, but studies have not been performed in larger animals, and the mechanisms are unknown. Specifically, age-associated changes in timecourse of senescence and related changes in inflammation and fibrosis are not well understood. Additionally, the cellular and systemic role of senescence and its inflammatory milieu in influencing arrhythmogenesis with age is not clear, particularly in large animal models with cardiac electrophysiology more similar to humans than previously studied animal models. Here, we investigated the role of senescence in regulating inflammation, fibrosis, and arrhythmogenesis in young and aged infarcted rabbits. Aged rabbits exhibited increased peri-procedural mortality and arrhythmogenic electrophysiological remodeling at the infarct border zone (IBZ) compared to young rabbits. Studies of the aged infarct zone revealed persistent myofibroblast senescence and increased inflammatory signaling over a 12-week timecourse. Senescent IBZ myofibroblasts in aged rabbits appear to be coupled to myocytes, and our computational modeling showed that senescent myofibroblast-cardiomyocyte coupling prolongs action potential duration (APD) and facilitates conduction block permissive of arrhythmias. Aged infarcted human ventricles show levels of senescence consistent with aged rabbits, and senescent myofibroblasts also couple to IBZ myocytes. Our findings suggest that therapeutic interventions targeting senescent cells may mitigate arrhythmias post-MI with age.

    1. Cell Biology
    Florian Geisler, Sanne Remmelzwaal ... Rudolf E Leube
    Research Article

    Intermediate filaments (IFs) are major components of the metazoan cytoskeleton. A long-standing debate concerns the question whether IF network organization only reflects or also determines cell and tissue function. Using C. elegans, we have recently described mutants of the MAPK SMA-5 which perturb the organization of the intestinal IF cytoskeleton resulting in luminal widening and cytoplasmic invaginations. Besides these structural phenotypes, systemic dysfunctions were also observed. We now identify the IF polypeptide IFB-2 as a highly efficient suppressor of both the structural and functional deficiencies of sma-5 animals, by removing the aberrant IF network. Mechanistically, perturbed IF network morphogenesis is linked to hyperphosphorylation of multiple sites throughout the entire IFB-2 molecule. The rescuing capability is IF isotype-specific and not restricted to SMA-5 mutants but extends to mutants that disrupt the function of the cytoskeletal linker IFO-1 and the IF-associated protein BBLN1. The findings provide strong evidence for adverse consequences of the deranged IF networks with implications for diseases that are characterized by altered IF network organization.