Maintenance of glucose homeostasis is central to our health, and its failure results in severe debilitating diseases including diabetes and familial hyperinsulinism. Diabetes mellitus is a metabolic disorder that affects over 285 million people worldwide and is a leading cause of death in many countries. The disease is characterized by either absolute insulin deficiency due to the autoimmune destruction of pancreatic insulin-producing ?-cells [Type 1 diabetes mellitus (T1DM)], or relative insulin deficiency due to defective insulin secretion or insulin sensitivity [Type 2 diabetes mellitus (T2DM)]. The resulting elevated blood glucose levels eventually lead to an impairment of the microvasculature followed by kidney failure, blindness, neuropathy and heart disease. Consequently, diabetes is currently the sixth leading cause of death in the United States (CDC). During the past grant cycle, we have made the exciting discovery that the imprinted MEG3 locus is strongly down-regulated in islets from type 2 diabetics. The MEG3 locus is of particular interest in that it encodes a cluster of 54 microRNAs, which we have found to target anti-apoptotic genes, suggesting that dysregulation of this locus contributes to ?-cell failure in type 2 diabetes. Here, we propose to investigate both epigenetic regulation and biological function of this locus in mouse and human ?-cells.
In Aim 1, we will investigate the molecular mechanism that causes dysregulation of the MEG3 locus in diabetes. Specifically, we will test the hypothesis that hyper-methylation of a differentially methylated region (DMR) near the promoter of the MEG3 gene causes loss of binding of ?-cell specific transcription factors in an enhancer in the MEG3 gene.
In Aim 2, we will determine the specific function of the MEG3 locus in ?-cell physiology and survival using both mouse genetic and innovative human epigenetic inactivation. Multiple biochemical and molecular assays will be performed on MEG3 deficient ?-cells. Together, these experiments will provide important new insights into the molecular etiology of ?-cell failure in type 2 diabetes.

Public Health Relevance

Regulation and function of the MEG3 locus in human beta-cells Renewal application for 5R01DK088383 Narrative Maintenance of glucose homeostasis is central to our health, and its failure results in severe debilitating diseases including diabetes ad familial hyperinsulinism. Diabetes mellitus is a metabolic disorder that affects over 285 million people worldwide and is a leading cause of death in many countries. We have discovered that an entire cluster of regulatory genes is de-activated in insulin-secreting cells from type 2 diabetc patients. In the current proposal, we aim to determine how this dysregulation occurs, and how these genes in this cluster control the function of insulin-secreting cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK088383-05
Application #
8759299
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Blondel, Olivier
Project Start
2010-05-20
Project End
2019-05-31
Budget Start
2014-08-01
Budget End
2015-05-31
Support Year
5
Fiscal Year
2014
Total Cost
$489,291
Indirect Cost
$177,882
Name
University of Pennsylvania
Department
Genetics
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Kameswaran, Vasumathi; Bramswig, Nuria C; McKenna, Lindsay B et al. (2014) Epigenetic regulation of the DLK1-MEG3 microRNA cluster in human type 2 diabetic islets. Cell Metab 19:135-45
Jiao, Yang; Le Lay, John; Yu, Ming et al. (2014) Elevated mouse hepatic betatrophin expression does not increase human *-cell replication in the transplant setting. Diabetes 63:1283-8
Santos, Gustavo Jorge Dos; Ferreira, Sandra Mara; Ortis, Fernanda et al. (2014) Metabolic memory of ß-cells controls insulin secretion and is mediated by CaMKII. Mol Metab 3:484-9
Bramswig, Nuria C; Kaestner, Klaus H (2014) Transcriptional and epigenetic regulation in human islets. Diabetologia 57:451-4
Avrahami, Dana; Li, Changhong; Yu, Ming et al. (2014) Targeting the cell cycle inhibitor p57Kip2 promotes adult human ? cell replication. J Clin Invest 124:670-4
Bramswig, Nuria C; Everett, Logan J; Schug, Jonathan et al. (2013) Epigenomic plasticity enables human pancreatic * to * cell reprogramming. J Clin Invest 123:1275-84
Xie, Ruiyu; Everett, Logan J; Lim, Hee-Woong et al. (2013) Dynamic chromatin remodeling mediated by polycomb proteins orchestrates pancreatic differentiation of human embryonic stem cells. Cell Stem Cell 12:224-37
Bramswig, Nuria C; Kaestner, Klaus H (2012) Organogenesis and functional genomics of the endocrine pancreas. Cell Mol Life Sci 69:2109-23