Overexpression of E2F3 promotes proliferation of functional human β cells without induction of apoptosis

Abstract

The mechanisms that control proliferation, or lack thereof, in adult human β cells are poorly understood. Controlled induction of proliferation could dramatically expand the clinical application of islet cell transplantation and represents an important component of regenerative approaches to a functional cure of diabetes. Adult human β cells are particularly resistant to common proliferative targets and often dedifferentiate during proliferation. Here we show that expression of the transcription factor E2F3 has a role in regulating β-cell quiescence and proliferation. We found human islets have virtually no expression of the pro-proliferative G₁/S transcription factors E2F1–3, but an abundance of inhibitory E2Fs 4–6. In proliferative human insulinomas, inhibitory E2Fs were absent, while E2F3 is expressed. Using this pattern as a “roadmap” for proliferation, we demonstrated that ectopic expression of nuclear E2F3 induced significant expansion of insulin-positive cells in both rat and human islets. These cells did not undergo apoptosis and retained their glucose-responsive insulin secretion, showing the ability to reverse diabetes in mice. Our results suggest that E2F4–6 may help maintain quiescence in human β cells and identify E2F3 as a novel target to induce proliferation of functional β cells. Refinement of this approach may increase the islets available for cell-based therapies and research and could provide important cues for understanding in vivo proliferation of β cells.

Keywords: :

• E2F
• E2F3
• cell cycle
• beta-cell proliferation
• islet transplant
• insulin-secreting cells
• beta-cell replication
• insulinoma
• type I diabetes

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Corrigendum

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Aknowledgements

Author contributions: experimental concept, design and execution, analysis and interpretation of data, drafting article, critical revisions of article, and final approval of version to be published by BAR; assistance with western blots YC; assistance with islet transplants, critical revisions of article, and final approval of article to be published PVS and YW, microfluidic assay performed by QW and YW, experimental concept and design, and final approval of article to be published by PS and JO. BAR and JO are the guarantors of this work and, as such, had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. We report no potential conflicts of interest related to this article.

We would like to acknowledge the Chicago Diabetes Project, Washington Square Health Foundation, the Christopher Family Foundation, and NIH R01 grant DK091526 for financial support, Andrew Stewart (Mount Sinai Hospital) for assistance with viral infections and proliferation assays and Julie Kerr-Conte (Université de Lille 2) for assistance with proliferation assays.