Despite the rigorous studies on pancreatic development over the past two decades, key questions remains regarding how functional beta cells can be derived. It is clear that a group of pancreatic progenitors activate proendocrine gene Ngn3 and its targets to regulate beta-cell development. It is not clear when are the progenitors committed to beta-cell fate and how the number of beta cells is determined during embryogenesis. These questions are particularly relevant to human diabetes. Several studies have demonstrated that endocrine differentiation from human ES/iPS cells in vitro can only produce insulin-expressing cells that lack necessary glucose response, underscoring our inability to derive proper endocrine progenitor cells with the right competence for beta-cell production. Furthermore, intrautarine factors that can lower the number of endocrine progenitors during embryogenesis predispose human and model organisms to late onset diabetes, highlighting the significance of obtaining sufficient numbers of pancreatic beta-cell progenitors i development. We have been studying a feed-forward gene expression loop, between Myt1 and Ngn3, to examine the basic mechanisms governing beta-cell development and function. We found that GAP junctions and microRNAs can both positively regulate Ngn3 expression, both the number of Ngn3+ cells and the relatively level of Ngn3 within each cell. These findings suggest that GAP junction-mediated communications are essential to coordinate the behaviors of progenitors for en masse beta-cell production. By developing an innovative bipartite Cre-based cell fate mapping, we also found that beta-cell fates are determined when or before Ngn3 is turned on. This beta-cell fate choice is mediated, at least partly, through the interaction between Myt1 and Ngn3. As a result, Myt1+Ngn3+ progenitor cells preferably give rise to beta cells, whereas Myt1-Ngn3+ cells give rise to alpha cells. Furthermore, we found that epigenetic modifiers can modulate the expression of Myt1 and the fate of the Myt1+Ngn3+ progenitors, and that Myt1 interacts with known chromatin modifiers including histone deacetylase Sin3A. Here in this grant renewal, we propose to investigate how GAP junction-mediated signals in conjunction with microRNAs and other epigenetic modifiers to regulate beta-cell production. We will first test a novel hypothesis that microRNAs can pass through GAP junctions to coordinate cellular differentiation to endocrine fate. We will then examine how epigenetic modifiers modulate Myt1 expression and how Myt1 interacts with other chromatin modifiers, such as Sin3A, to direct beta-cell fate choice over other endocrine cell types. Routine cell purification and genetic manipulations will be utilized to accomplish these goals. We envision these mechanistic studies to provide instrumental details regarding earlier developmental events that could affect beta-cell function in later physiology. Translating these knowledge to human tissues can directly help with derivation of functional islets from human ES/iPS cells for usage in curing Type I diabetes and help with designing ways to enhance beta-cell function for Type II diabetes.

Public Health Relevance

The goal of this competitive renewal is to examine how cell-cell communications with gap junction and microRNAs allow proper pancreatic progenitors to develop into functional beta cells. We expect to uncover novel positive regulators to enhance beta cell production and function. We envision the basic mechanism revealed by these studies will help with functional derivation from human ES/iPS cells for diabetes therapy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK065949-11
Application #
8760888
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Sato, Sheryl M
Project Start
2003-12-15
Project End
2018-08-31
Budget Start
2014-09-01
Budget End
2015-08-31
Support Year
11
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
City
Nashville
State
TN
Country
United States
Zip Code
37212
Zhu, Xiaodong; Hu, Ruiying; Brissova, Marcela et al. (2015) Microtubules Negatively Regulate Insulin Secretion in Pancreatic β Cells. Dev Cell 34:656-68
Kao, Der-I; Lacko, Lauretta A; Ding, Bi-Sen et al. (2015) Endothelial cells control pancreatic cell fate at defined stages through EGFL7 signaling. Stem Cell Reports 4:181-9
Arcidiacono, Biagio; Iiritano, Stefania; Chiefari, Eusebio et al. (2014) Cooperation between HMGA1, PDX-1, and MafA is Essential for Glucose-Induced Insulin Transcription in Pancreatic Beta Cells. Front Endocrinol (Lausanne) 5:237
Baeyens, Luc; Lemper, Marie; Leuckx, Gunter et al. (2014) Transient cytokine treatment induces acinar cell reprogramming and regenerates functional beta cell mass in diabetic mice. Nat Biotechnol 32:76-83
Chera, Simona; Baronnier, Delphine; Ghila, Luiza et al. (2014) Diabetes recovery by age-dependent conversion of pancreatic δ-cells into insulin producers. Nature 514:503-7
Yanger, Kilangsungla; Knigin, David; Zong, Yiwei et al. (2014) Adult hepatocytes are generated by self-duplication rather than stem cell differentiation. Cell Stem Cell 15:340-9
Sancho, Rocio; Gruber, Ralph; Gu, Guoqiang et al. (2014) Loss of Fbw7 reprograms adult pancreatic ductal cells into α, δ, and β cells. Cell Stem Cell 15:139-53
Sugiyama, Takuya; Benitez, Cecil M; Ghodasara, Amar et al. (2013) Reconstituting pancreas development from purified progenitor cells reveals genes essential for islet differentiation. Proc Natl Acad Sci U S A 110:12691-6
Hickey, Raymond D; Galivo, Feorillo; Schug, Jonathan et al. (2013) Generation of islet-like cells from mouse gall bladder by direct ex vivo reprogramming. Stem Cell Res 11:503-15
Liu, Jing; Willet, Spencer G; Bankaitis, Eric D et al. (2013) Non-parallel recombination limits Cre-LoxP-based reporters as precise indicators of conditional genetic manipulation. Genesis 51:436-42

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