While islet transplantation shows promise as a long-term treatment for Type 1 diabetes, the supply of available donor tissue is limiting. It is thus critical to identify factors that regulate islet differentiation and function, with the goal of generating a replenishable supply of islets from pancreatic or embryonic stem cells. The HNF6 transcription factor is critical for endocrine differentiation and islet function. HNF6 is expressed throughout the pancreas during development, but becomes permanently down-regulated in endocrine cells just before birth, as islets are forming. HNF6 -/- mice have delayed endocrine differentiation, fewer endocrine cells, abnormal islet architecture, and diabetes. HNF6 activated expression of the critical proendocrine transcription factor, ngn3 (ngn3 mutant mice lack all pancreatic endocrine cells). The results of the global HNF6 knockout demonstrate that HNF6 function is essential for normal endocrine development, but can not distinguish whether HNF6 is required only at the earliest stages of endocrine development to activate ngn3, or whether HNF6 functions continuously throughout endocrine development to promote terminal differentiation of endocrine cells. The goal of this proposal is to elucidate the role of HNF6 during islet endocrine development. Using mice in which HNF6 can be either up-regulated or inactivated conditionally, we will analyze the role of HNF6 in specification, proliferation, and differentiation of pancreatic cells to the endocrine lineage. To dissect the role of HNF6 in endocrine precursor proliferation and differentiation, HNF6 expression will be activated at different developmental time points, using a reversibly inducible endocrine-specific transgene. We will determine whether HNF6 over-expression during early embryonic stages stimulates increased specification and/or differentiation of endocrine precursors and the developmental window during which HNF6 can affect endocrine specification. Using cell type-specific and inducible Cre-lox strategies, the HNF6 gene will be selectively inactivated at different stages along the pathway of endocrine development including: progenitor specification, proliferation, diversification of endocrine cell types, and terminal differentiation. These studies will determine the embryonic stage(s) during which HNF6 plays a critical role in the development of the endocrine lineage, i.e. is HNF6 needed only at early stages of endocrine specification, or is it required continuously during embryogenesis for terminal differentiation and acquisition of mature function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
3R01DK065131-05S1
Application #
8010997
Study Section
Metabolism Study Section (MET)
Program Officer
Sato, Sheryl M
Project Start
2010-02-01
Project End
2010-04-30
Budget Start
2010-02-01
Budget End
2010-04-30
Support Year
5
Fiscal Year
2010
Total Cost
$18,000
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Vanderpool, Charles; Sparks, Erin E; Huppert, Kari A et al. (2012) Genetic interactions between hepatocyte nuclear factor-6 and Notch signaling regulate mouse intrahepatic bile duct development in vivo. Hepatology 55:233-43
Wicksteed, Barton; Brissova, Marcela; Yan, Wenbo et al. (2010) Conditional gene targeting in mouse pancreatic ß-Cells: analysis of ectopic Cre transgene expression in the brain. Diabetes 59:3090-8
Zhang, Hongjie; Ables, Elizabeth Tweedie; Pope, Christine F et al. (2009) Multiple, temporal-specific roles for HNF6 in pancreatic endocrine and ductal differentiation. Mech Dev 126:958-73
Guney, Michelle A; Gannon, Maureen (2009) Pancreas cell fate. Birth Defects Res C Embryo Today 87:232-48
Crawford, Laura A; Guney, Michelle A; Oh, Young Ah et al. (2009) Connective tissue growth factor (CTGF) inactivation leads to defects in islet cell lineage allocation and beta-cell proliferation during embryogenesis. Mol Endocrinol 23:324-36
Wilding Crawford, Laura; Tweedie Ables, Elizabeth; Oh, Young Ah et al. (2008) Gene expression profiling of a mouse model of pancreatic islet dysmorphogenesis. PLoS One 3:e1611
Wiebe, Peter O; Kormish, Jay D; Roper, Venus T et al. (2007) Ptf1a binds to and activates area III, a highly conserved region of the Pdx1 promoter that mediates early pancreas-wide Pdx1 expression. Mol Cell Biol 27:4093-104
Kanetsuna, Yukiko; Hirano, Keita; Nagata, Michio et al. (2006) Characterization of diabetic nephropathy in a transgenic model of hypoinsulinemic diabetes. Am J Physiol Renal Physiol 291:F1315-22
Tweedie, Elizabeth; Artner, Isabella; Crawford, Laura et al. (2006) Maintenance of hepatic nuclear factor 6 in postnatal islets impairs terminal differentiation and function of beta-cells. Diabetes 55:3264-70
Zhang, Hongjie; Fujitani, Yoshio; Wright, Christopher V E et al. (2005) Efficient recombination in pancreatic islets by a tamoxifen-inducible Cre-recombinase. Genesis 42:210-7

Showing the most recent 10 out of 11 publications