Go to The Journal of Clinical Investigation
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Transfers
  • Advertising/recruitment
  • Contact
  • Current Issue
  • Past Issues
  • By specialty
    • Cardiology
    • Immunology
    • Metabolism
    • Nephrology
    • Oncology
    • Pulmonology
    • All...
  • Videos
  • Collections
    • Recently published
    • Technical Advances
    • Clinical Medicine
    • Reviews
    • Editorials
    • Perspectives
    • Top read articles
  • JCI This Month
    • Current issue
    • Past issues

  • About
  • Editors
  • Consulting Editors
  • For authors
  • Transfers
  • Current issue
  • Past issues
  • By specialty
  • Contact
  • Recently published
  • Technical Advances
  • Clinical Medicine
  • Editorials
  • Top read articles
A glucose-dependent spatial patterning of exocytosis in human β cells is disrupted in type 2 diabetes
Jianyang Fu, … , Herbert Y. Gaisano, Patrick E. MacDonald
Jianyang Fu, … , Herbert Y. Gaisano, Patrick E. MacDonald
Published June 20, 2019; First published May 14, 2019
Citation Information: JCI Insight. 2019;4(12):e127896. https://doi.org/10.1172/jci.insight.127896.
View: Text | PDF
Categories: Research Article Cell biology Endocrinology

A glucose-dependent spatial patterning of exocytosis in human β cells is disrupted in type 2 diabetes

  • Text
  • PDF
Abstract

Impaired insulin secretion in type 2 diabetes (T2D) is linked to reduced insulin granule docking, disorganization of the exocytotic site, and impaired glucose-dependent facilitation of insulin exocytosis. We show in β cells from 80 human donors that the glucose-dependent amplification of exocytosis is disrupted in T2D. Spatial analyses of granule fusion events, visualized by total internal reflection fluorescence microscopy in 24 of these donors, demonstrated that these events are nonrandom across the surface of β cells from donors with no diabetes. The compartmentalization of events occurs within regions defined by concurrent or recent membrane-resident secretory granules. This organization, and the number of membrane-associated granules, is glucose dependent and notably impaired in T2D β cells. Mechanistically, multichannel Kv2.1 clusters contribute to maintaining the density of membrane-resident granules and the number of fusion “hotspots,” while SUMOylation sites at the channel N- (K145) and C-terminus (K470) determine the relative proportion of fusion events occurring within these regions. Thus, a glucose-dependent compartmentalization of fusion, regulated in part by a structural role for Kv2.1, is disrupted in β cells from donors with T2D.

Authors

Jianyang Fu, John Maringa Githaka, Xiaoqing Dai, Gregory Plummer, Kunimasa Suzuki, Aliya F. Spigelman, Austin Bautista, Ryekjang Kim, Dafna Greitzer-Antes, Jocelyn E. Manning Fox, Herbert Y. Gaisano, Patrick E. MacDonald

×

Figure 6

Upregulation of Kv2.1 restores the spatial organization of fusion sites in T2D β cells.

Options: View larger image (or click on image) Download as PowerPoint
Upregulation of Kv2.1 restores the spatial organization of fusion sites ...
(A) In ND β cells, compared with the full-length channel (Kv2.1-WT), a clustering-deficient mutant (Kv2.1-ΔC318) reduced the uniformity of fusion events monitored by TIRF imaging of granule-targeted NPY-EGFP (n = 22, 26, and 24 cells from 3 donors). Cells expressing the channel constructs were identified by channel-tagged mCherry and compared to cells expressing mCherry alone. (B) In a subset of cells with equivalent rates of exocytosis (dashed box), (C) expression of Kv2.1-WT had little effect on the proportion of events within hotspots and (D) slightly increased their density, while Kv2.1-ΔC318 reduced the overall contribution of hotspots to exocytosis. (E–H) Same as A–D, but in T2D β cells (n = 12, 16, and 10 cells from 3 donors). Here, Kv2.1-WT rescued the compartmentalization of fusion events. (F) In a subset of cells with similar fusion frequency (dashed box), (G) the overall proportion of events occurring in these spatially restricted regions and (H) the density of these sites are unchanged by WT-Kv2.1. Significance was determined by Kruskal-Wallis 1-way ANOVA followed by (A and H) Mann-Whitney posttest or by (C–E and G) ANOVA and Bonferroni’s posttest. *P < 0.05; **P < 0.01; ***P < 0.001.
Follow JCI Insight:
Copyright © 2019 American Society for Clinical Investigation
ISSN 2379-3708

Sign up for email alerts