1. Cell Biology
  2. Structural Biology and Molecular Biophysics
Download icon

Ca2+ signaling driving pacemaker activity in submucosal interstitial cells of Cajal in the murine colon

  1. Salah A Baker  Is a corresponding author
  2. Wesley A Leigh
  3. Guillermo Del Valle
  4. Inigo F De Yturriaga
  5. Sean M Ward
  6. Caroline A Cobine
  7. Bernard T Drumm
  8. Kenton M Sanders
  1. University of Nevada, Reno, United States
  2. Institute of Technology, Dundalk, Ireland
  3. University of Nevada, United States
Research Article
  • Cited 1
  • Views 789
  • Annotations
Cite this article as: eLife 2021;10:e64099 doi: 10.7554/eLife.64099

Abstract

Interstitial cells of Cajal (ICC) generate pacemaker activity responsible for phasic contractions in colonic segmentation and peristalsis. ICC along the submucosal border (ICC-SM) contribute to mixing and more complex patterns of colonic motility. We show the complex patterns of Ca2+ signaling in ICC-SM and the relationship between ICC-SM Ca2+ transients and activation of SMCs using optogenetic tools. ICC-SM displayed rhythmic firing of Ca2+ transients ~15 cpm and paced adjacent SMCs. The majority of spontaneous activity occurred in regular Ca2+ transients clusters (CTCs) that propagated through the network. CTCs were organized and dependent upon Ca2+ entry through voltage-dependent Ca2+ conductances, L- and T-type Ca2+ channels. Removal of Ca2+ from the external solution abolished CTCs. Ca2+ release mechanisms reduced the duration and amplitude of Ca2+ transients but did not block CTCs. These data reveal how colonic pacemaker ICC-SM exhibit complex Ca2+ firing patterns and drive smooth muscle activity and overall colonic contractions.

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. Salah A Baker

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    For correspondence
    sabubaker@med.unr.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1514-6876
  2. Wesley A Leigh

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Guillermo Del Valle

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Inigo F De Yturriaga

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Sean M Ward

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Caroline A Cobine

    Physiology and Cell Biology, University of Nevada, Reno, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Bernard T Drumm

    Department of Life & Health Science,, Institute of Technology, Dundalk, Dundalk, Ireland
    Competing interests
    The authors declare that no competing interests exist.
  8. Kenton M Sanders

    Physiology and Cell Biology, University of Nevada, Reno, United States
    Competing interests
    The authors declare that no competing interests exist.

Funding

National Institute of Diabetes and Digestive and Kidney Diseases (R01 DK-120759)

  • Salah A Baker

National Institute of Diabetes and Digestive and Kidney Diseases (R01 DK-120759)

  • Kenton M Sanders

National Institute of Diabetes and Digestive and Kidney Diseases (R01 DK-078736)

  • Caroline A Cobine

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

Ethics

Animal experimentation: The animals used, protocols performed and procedures in this study were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and approved by the Institutional Animal Use and Care Committee at the University of Nevada, Reno (IACUC; Protocol# 00053).

Reviewing Editor

  1. Mark T Nelson, University of Vermont, United States

Publication history

  1. Received: October 16, 2020
  2. Accepted: January 4, 2021
  3. Accepted Manuscript published: January 5, 2021 (version 1)
  4. Version of Record published: January 13, 2021 (version 2)

Copyright

© 2021, Baker 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

  • 789
    Page views
  • 108
    Downloads
  • 1
    Citations

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

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)

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

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

Further reading

    1. Biochemistry and Chemical Biology
    2. Cell Biology
    Zdravka Daneva et al.
    Research Article Updated

    Pannexin 1 (Panx1), an ATP-efflux pathway, has been linked with inflammation in pulmonary capillaries. However, the physiological roles of endothelial Panx1 in the pulmonary vasculature are unknown. Endothelial transient receptor potential vanilloid 4 (TRPV4) channels lower pulmonary artery (PA) contractility and exogenous ATP activates endothelial TRPV4 channels. We hypothesized that endothelial Panx1–ATP–TRPV4 channel signaling promotes vasodilation and lowers pulmonary arterial pressure (PAP). Endothelial, but not smooth muscle, knockout of Panx1 increased PA contractility and raised PAP in mice. Flow/shear stress increased ATP efflux through endothelial Panx1 in PAs. Panx1-effluxed extracellular ATP signaled through purinergic P2Y2 receptor (P2Y2R) to activate protein kinase Cα (PKCα), which in turn activated endothelial TRPV4 channels. Finally, caveolin-1 provided a signaling scaffold for endothelial Panx1, P2Y2R, PKCα, and TRPV4 channels in PAs, promoting their spatial proximity and enabling signaling interactions. These results indicate that endothelial Panx1–P2Y2R–TRPV4 channel signaling, facilitated by caveolin-1, reduces PA contractility and lowers PAP in mice.

    1. Cell Biology
    Adria Razzauti, Patrick FM Laurent
    Research Article

    Cilia are sensory organelles protruding from cell surfaces. Release of Extracellular Vesicles (EVs) from cilia was previously observed in mammals, Chlamydomonas, and in male C. elegans. Using the EV marker TSP-6 (an ortholog of mammalian CD9) and other ciliary receptors, we show that EVs are formed from ciliated sensory neurons in C. elegans hermaphrodites. Release of EVs is observed from two ciliary locations: the cilia tip and/or Periciliary Membrane Compartment (PCMC). Outward budding of EVs from the cilia tip leads to their release into the environment. EVs budding from the PCMC are concomitantly phagocytosed by the associated glial cells. To maintain cilia composition, a tight regulation of cargo import and removal is achieved by the action of Intra-Flagellar Transport (IFT). Unbalanced IFT due to cargo overexpression or mutations in the IFT machinery leads to local accumulation of ciliary proteins. Disposal of excess ciliary proteins via EVs reduces their local accumulation and exports them to the environment and/or to the glia associated to these ciliated neurons. We suggest that EV budding from cilia subcompartments acts as a safeguard mechanism to remove deleterious excess of ciliary material.