1. Cell Biology
  2. Developmental Biology
Download icon

Reduced synchroneity of intra-islet Ca2+ oscillations in vivo in Robo-deficient β cells

  1. Melissa T Adams
  2. JaeAnn M Dwulet
  3. Jennifer K Briggs
  4. Christopher A Reissaus
  5. Erli Jin
  6. Joseph M Szulczewski
  7. Melissa R Lyman
  8. Sophia M Sdao
  9. Vira Kravets
  10. Sutichot D Nimkulrat
  11. Suzanne M Ponik
  12. Matthew J Merrins
  13. Raghavendra G Mirmira
  14. Amelia K Linnemann
  15. Richard KP Benninger
  16. Barak Blum  Is a corresponding author
  1. University of Wisconsin-Madison, United States
  2. University of Colorado Denver, Anschutz Medical Campus, United States
  3. Indiana University School of Medicine, United States
  4. University of Colorado-Denver, United States
  5. University of Chicago, United States
Research Article
  • Cited 1
  • Views 1,110
  • Annotations
Cite this article as: eLife 2021;10:e61308 doi: 10.7554/eLife.61308

Abstract

The spatial architecture of the islets of Langerhans is hypothesized to facilitate synchronized insulin secretion among β cells yet testing this in vivo in the intact pancreas is challenging. Robo βKO mice, in which the genes Robo1 and Robo2 are deleted selectively in β cells, provide a unique model of altered islet spatial architecture without loss of β cell differentiation or islet damage from diabetes. Combining Robo βKO mice with intravital microscopy, we show here that Robo βKO islets have reduced synchronized intra-islet Ca2+ oscillations among β cells in vivo. We provide evidence that this loss is not due to a β cell-intrinsic function of Robo, mis-expression or mis-localization of Cx36 gap junctions, or changes in islet vascularization or innervation, suggesting that the islet architecture itself is required for synchronized Ca2+ oscillations. These results have implications for understanding structure-function relationships in the islets during progression to diabetes as well as engineering islets from stem cells.

Data availability

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

Article and author information

Author details

  1. Melissa T Adams

    Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. JaeAnn M Dwulet

    Department of Bioengineering and Barbara Davis Center for Diabetes, University of Colorado Denver, Anschutz Medical Campus, Aurora, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2519-5193
  3. Jennifer K Briggs

    Department of Bioengineering and Barbara Davis Center for Diabetes, University of Colorado Denver, Anschutz Medical Campus, Aurora, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Christopher A Reissaus

    Herman B Wells Center for Pediatric Research and Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Erli Jin

    Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Joseph M Szulczewski

    Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Melissa R Lyman

    Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0091-0413
  8. Sophia M Sdao

    Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  9. Vira Kravets

    Bioengineering, University of Colorado-Denver, Aurora, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5147-309X
  10. Sutichot D Nimkulrat

    Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  11. Suzanne M Ponik

    Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  12. Matthew J Merrins

    Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, United States
    Competing interests
    The authors declare that no competing interests exist.
  13. Raghavendra G Mirmira

    Kovler Diabetes Center and the Department of Medicine, University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  14. Amelia K Linnemann

    Herman B Wells Center for Pediatric Research and Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, United States
    Competing interests
    The authors declare that no competing interests exist.
  15. Richard KP Benninger

    Department of Bioengineering and Barbara Davis Center for Diabetes, University of Colorado Denver, Anschutz Medical Campus, Aurora, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5063-6096
  16. Barak Blum

    Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, United States
    For correspondence
    bblum4@wisc.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5308-4194

Funding

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK121706)

  • Barak Blum

American Diabetes Association (ADA 1-16-IBS-212)

  • Matthew J Merrins

National Institute of General Medical Sciences (5T32GM007133-44)

  • Melissa T Adams

National Institute of Diabetes and Digestive and Kidney Diseases (P30DK020579)

  • Barak Blum

UW-Madison Institute for Clinical and Translational Research (UL1TR000427)

  • Matthew J Merrins
  • Barak Blum

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK060581)

  • Raghavendra G Mirmira

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK102950)

  • Richard KP Benninger

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK106412)

  • Richard KP Benninger

National Cancer Institute (R01CA216248)

  • Suzanne M Ponik

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK113103)

  • Matthew J Merrins

National Institute on Aging (R01AG062328)

  • Matthew J Merrins

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 experimental protocol for animal usage was reviewed and approved by the University of Wisconsin-Madison Institutional Animal Care and Use Committee (IACUC) under Protocol #M005221 and Protocol #M005333, and all animal experiments were conducted in accordance with the University of Wisconsin-Madison IACUC guidelines under the approved protocol.

Reviewing Editor

  1. Guy A Rutter, Imperial College London, United Kingdom

Publication history

  1. Received: July 22, 2020
  2. Accepted: July 6, 2021
  3. Accepted Manuscript published: July 7, 2021 (version 1)
  4. Version of Record published: July 19, 2021 (version 2)

Copyright

© 2021, Adams 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

  • 1,110
    Page views
  • 133
    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
    Aixin Song et al.
    Research Article Updated

    UCH37, also known as UCHL5, is a highly conserved deubiquitinating enzyme (DUB) that associates with the 26S proteasome. Recently, it was reported that UCH37 activity is stimulated by branched ubiquitin (Ub) chain architectures. To understand how UCH37 achieves its unique debranching specificity, we performed biochemical and Nuclear Magnetic Resonance (NMR) structural analyses and found that UCH37 is activated by contacts with the hydrophobic patches of both distal Ubs that emanate from a branched Ub. In addition, RPN13, which recruits UCH37 to the proteasome, further enhances branched-chain specificity by restricting linear Ub chains from having access to the UCH37 active site. In cultured human cells under conditions of proteolytic stress, we show that substrate clearance by the proteasome is promoted by both binding and deubiquitination of branched polyubiquitin by UCH37. Proteasomes containing UCH37(C88A), which is catalytically inactive, aberrantly retain polyubiquitinated species as well as the RAD23B substrate shuttle factor, suggesting a defect in recycling of the proteasome for the next round of substrate processing. These findings provide a foundation to understand how proteasome degradation of substrates modified by a unique Ub chain architecture is aided by a DUB.

    1. Cell Biology
    2. Neuroscience
    Domenica Ippolito et al.
    Research Article Updated

    Sensory and behavioral plasticity are essential for animals to thrive in changing environments. As key effectors of intracellular calcium signaling, Ca2+/calmodulin-dependent protein kinases (CaMKs) can bridge neural activation with the many regulatory processes needed to orchestrate sensory adaptation, including by relaying signals to the nucleus. Here, we elucidate the molecular mechanism controlling the cell activation-dependent nuclear translocation of CMK-1, the Caenorhabditis elegans ortholog of mammalian CaMKI/IV, in thermosensory neurons in vivo. We show that an intracellular Ca2+ concentration elevation is necessary and sufficient to favor CMK-1 nuclear import. The binding of Ca2+/CaM to CMK-1 increases its affinity for IMA-3 importin, causing a redistribution with a relatively slow kinetics, matching the timescale of sensory adaptation. Furthermore, we show that this mechanism enables the encoding of opposite nuclear signals in neuron types with opposite calcium-responses and that it is essential for experience-dependent behavioral plasticity and gene transcription control in vivo. Since CaMKI/IV are conserved regulators of adaptable behaviors, similar mechanisms could exist in other organisms and for other sensory modalities.