Hedgehog (Hh) signaling regulates cell proliferation and differentiation in various organs during embryogenesis. In the pancreas, the role of this pathway is complex. At early stages, Hh signaling is excluded from the pancreas and ectopic activation of the pathway impairs pancreas formation by disturbing mesenchymal-epithelial interactions. In contrast to this inhibitory role, our preliminary data suggest a positive, cell autonomous role for Hh signaling during endocrine cell formation and function. The exact nature of this novel, cell autonomous activity remains to be elucidated. Little information is also available about the upstream mechanisms that regulate Hh signaling in pancreatic epithelium. Recent results have revealed that primary cilia, cellular appendages found on many cell types, control the level of Hh signaling activity. Primary cilia are present on adult duct and endocrine cells within the pancreas, the same cell types that are marked by expression of Ptc, a transcriptional target gene of Hh signaling. Our preliminary results indicate that cilia control activation of Hh signaling in pancreatic cells. In the first specific aim, we will address the cell autonomous requirement for Hh signaling in pancreatic epithelium. This will be accomplished by analyzing transgenic mice in which Smoothened, the gene coding for an essential component of the Hh pathway, has been eliminated specifically in pancreatic epithelial cells. In the second specific aim, we propose to elucidate the role of cilia in regulating the level of Hh signaling in pancreatic epithelium and in endocrine ?-cells. Transgenic mice ectopically expressing GLI2, a transcriptional activator of Hh signaling, in pancreatic epithelial and ?-cells that lack primary cilia have been generated for this purpose. In the third specific aim, we will perform cell culture experiments to analyze the mechanisms by which primary cilia control Hh activity in pancreatic cells. In summary, experiments proposed in this application will address the cell autonomous requirement for Hh signaling in pancreatic epithelial cells and the role primary cilia play in regulating the level of Hh activity in these cells. Given the distinct roles Hh signaling plays at different time points during pancreas and endocrine cell development and function, understanding of these effects will help to optimize strategies designed to generate functional ?-cells from embryonic stem cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK060533-09
Application #
8018122
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Sato, Sheryl M
Project Start
2001-12-01
Project End
2013-02-28
Budget Start
2011-03-01
Budget End
2012-02-29
Support Year
9
Fiscal Year
2011
Total Cost
$317,914
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Folias, Alexandra E; Hebrok, Matthias (2014) Diabetes. Solving human ?-cell development--what does the mouse say? Nat Rev Endocrinol 10:253-5
Puri, Sapna; Akiyama, Haruhiko; Hebrok, Matthias (2013) VHL-mediated disruption of Sox9 activity compromises ?-cell identity and results in diabetes mellitus. Genes Dev 27:2563-75
Puri, Sapna; García-Núñez, Alejandro; Hebrok, Matthias et al. (2013) Elimination of von Hippel-Lindau function perturbs pancreas endocrine homeostasis in mice. PLoS One 8:e72213
Puri, Sapna; Hebrok, Matthias (2012) Diabetic ýý Cells: To Be or Not To Be? Cell 150:1103-4
Landsman, Limor; Parent, Audrey; Hebrok, Matthias (2011) Elevated Hedgehog/Gli signaling causes beta-cell dedifferentiation in mice. Proc Natl Acad Sci U S A 108:17010-5
Landsman, Limor; Nijagal, Amar; Whitchurch, Theresa J et al. (2011) Pancreatic mesenchyme regulates epithelial organogenesis throughout development. PLoS Biol 9:e1001143
Cervantes, Sara; Lau, Janet; Cano, David A et al. (2010) Primary cilia regulate Gli/Hedgehog activation in pancreas. Proc Natl Acad Sci U S A 107:10109-14
Lau, Janet; Hebrok, Matthias (2010) Hedgehog signaling in pancreas epithelium regulates embryonic organ formation and adult beta-cell function. Diabetes 59:1211-21
Puri, Sapna; Hebrok, Matthias (2010) Cellular plasticity within the pancreas--lessons learned from development. Dev Cell 18:342-56
Kockel, Lutz; Kerr, Kimberly S; Melnick, Michael et al. (2010) Dynamic switch of negative feedback regulation in Drosophila Akt-TOR signaling. PLoS Genet 6:e1000990

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