Age-dependent human β cell proliferation induced by glucagon-like peptide 1 and calcineurin signaling
Chunhua Dai, … , Seung K. Kim, Alvin C. Powers
Chunhua Dai, … , Seung K. Kim, Alvin C. Powers
Published September 18, 2017
Citation Information: J Clin Invest. 2017;127(10):3835-3844. https://doi.org/10.1172/JCI91761.
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Research Article Endocrinology

Age-dependent human β cell proliferation induced by glucagon-like peptide 1 and calcineurin signaling

Abstract

Inadequate pancreatic β cell function underlies type 1 and type 2 diabetes mellitus. Strategies to expand functional cells have focused on discovering and controlling mechanisms that limit the proliferation of human β cells. Here, we developed an engraftment strategy to examine age-associated human islet cell replication competence and reveal mechanisms underlying age-dependent decline of β cell proliferation in human islets. We found that exendin-4 (Ex-4), an agonist of the glucagon-like peptide 1 receptor (GLP-1R), stimulates human β cell proliferation in juvenile but not adult islets. This age-dependent responsiveness does not reflect loss of GLP-1R signaling in adult islets, since Ex-4 treatment stimulated insulin secretion by both juvenile and adult human β cells. We show that the mitogenic effect of Ex-4 requires calcineurin/nuclear factor of activated T cells (NFAT) signaling. In juvenile islets, Ex-4 induced expression of calcineurin/NFAT signaling components as well as target genes for proliferation-promoting factors, including NFATC1, FOXM1, and CCNA1. By contrast, expression of these factors in adult islet β cells was not affected by Ex-4 exposure. These studies reveal age-dependent signaling mechanisms regulating human β cell proliferation, and identify elements that could be adapted for therapeutic expansion of human β cells.

Authors

Chunhua Dai, Yan Hang, Alena Shostak, Greg Poffenberger, Nathaniel Hart, Nripesh Prasad, Neil Phillips, Shawn E. Levy, Dale L. Greiner, Leonard D. Shultz, Rita Bottino, Seung K. Kim, Alvin C. Powers

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Figure 4

Calcineurin/NFAT signaling mediates the mitogenic effect of Ex-4 in juvenile β cells.

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Calcineurin/NFAT signaling mediates the mitogenic effect of Ex-4 in juve...
(A) Ex-4 stimulated NFAT translocation. Insulin (green), NFATC4 (NFAT3) (red), DAPI (blue). Scale bar: 15 μm (applies to the other images in A). Arrows point to NFATC4+ β cells, and insets show NFATC4+ β cells. (B) Representative images of β cell proliferation in juvenile grafts. Insulin (green), Ki67 (red), DAPI (blue). Arrows point to proliferating Ki67+ cells (also showed in insets). Scale bar: 35 μm. (C) FK506 blocked the β cell proliferation stimulated by Ex-4 in juvenile grafts (n = 4 donors, 0.2, 1.8, 6, and 9 years old). See also Supplemental Figure 6. (D) Representative images of TUNEL assay including positive control. Insulin (green), TUNEL (red), DAPI (blue). Scale bar: 50 μm (applies to all images in D). See Table 1 for the quantification of TUNEL+ β cells in PBS+saline–treated, Ex-4+saline–treated, PBS+FK506–treated, and Ex-4+FK506–treated graft samples from 3 juvenile donors. Error bars represent SEM. **P < 0.01. Unpaired 2-tailed Student’s t test or 1-way ANOVA followed by Newman-Keuls multiple-comparisons test (C) was used for statistical analysis. See also Supplemental Figure 6.