Targeting the cell cycle inhibitor p57Kip2 promotes adult human β cell replication
Dana Avrahami, … , Benjamin Glaser, Klaus H. Kaestner
Dana Avrahami, … , Benjamin Glaser, Klaus H. Kaestner
Published January 16, 2014
Citation Information: J Clin Invest. 2014;124(2):670-674. https://doi.org/10.1172/JCI69519.
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Brief Report Metabolism

Targeting the cell cycle inhibitor p57Kip2 promotes adult human β cell replication

Abstract

Children with focal hyperinsulinism of infancy display a dramatic, non-neoplastic clonal expansion of β cells that have undergone mitotic recombination, resulting in paternal disomy of part of chromosome 11. This disomic region contains imprinted genes, including the gene encoding the cell cycle inhibitor p57Kip2 (CDKN1C), which is silenced as a consequence of the recombination event. We hypothesized that targeting p57Kip2 could stimulate adult human β cell replication. Indeed, when we suppressed CDKN1C expression in human islets obtained from deceased adult organ donors and transplanted them into hyperglycemic, immunodeficient mice, β cell replication increased more than 3-fold. The newly replicated cells retained properties of mature β cells, including the expression of β cell markers such as insulin, PDX1, and NKX6.1. Importantly, these newly replicated cells demonstrated normal glucose-induced calcium influx, further indicating β cell functionality. These findings provide a molecular explanation for the massive β cell replication that occurs in children with focal hyperinsulinism. These data also provided evidence that β cells from older humans, in which baseline replication is negligible, can be coaxed to re-enter and complete the cell cycle while maintaining mature β cell properties. Thus, controlled manipulation of this pathway holds promise for the expansion of β cells in patients with type 2 diabetes.

Authors

Dana Avrahami, Changhong Li, Ming Yu, Yang Jiao, Jia Zhang, Ali Naji, Seyed Ziaie, Benjamin Glaser, Klaus H. Kaestner

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Figure 2

Increased β cell replication in p57Kip2-suppressed human islets.

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Increased β cell replication in p57Kip2-suppressed human islets. (A) B...
(A) Blood glucose levels of STZ-treated immunodeficient mice transplanted with p57Kip2-suppressed (blue line) and control human islets (red line) were not statistically different (n = 9 mice per group). (B) BrdU-positive β cells in shRNA lentiviral–transduced, engrafted human islets. Average percentage of BrdU-positive β cells in p57Kip2-suppressed islets (blue bars, 2.71%) was significantly higher (*P < 0.01) than in NT shRNA–transduced islets (red bars, 0.84%). (C) Human and mouse C-peptide levels of mice transplanted with p57Kip2-suppressed and control human islets (blue and red bars, respectively) just before graft recovery (n = 6 per group). (D) Proliferating β cells in p57Kip2-suppressed human islets show negligible p57Kip2 levels. Costaining for p57Kip2 (white), insulin (green), BrdU (red), and DNA (blue). Arrows point to BrdU-positive/p57Kip2-negative β cells. (E) No activation of the DNA damage response by p57Kip2 suppression was observed. Costaining for γH2AX (white), insulin (green), BrdU (red), and DNA (blue). Arrows point to BrdU-positive/γH2AX-negative β cells. (F) Forced cell cycle entry by overexpression of HNF4α induces the DNA damage response. Costaining for γH2AX (white), BrdU (red), and DNA (blue). Arrows point to BrdU/γH2AX double-positive islet cells. (G) 25% ± 9.5% (SD) of newly replicated β cells are doublets. Costaining for PDX1 (green), BrdU (red), and nuclei (blue). Arrows point to BrdU/PDX1 double-positive β cells in close proximity to one another. (H) Some newly replicated β cells stain for the cell cycle marker Ki67. Costaining for Ki67 (white), insulin (green), BrdU (red), and DNA (blue). Arrow points to a BrdU/insulin/Ki67-positive β cell. Scale bars: 20 μm.