The small intestinal epithelium is organized into flask-like glands (crypts) that contain intestinal stem cells and finger-like projections (villi) covered by differentiated cells. A constant process of cell division, differentiation and migration is established along a polarized crypt to villus axis. Establishment and maintenance of this vertical axis requires cell:cell crosstalk between the epithelium and the underlying mesenchyme and is critical to proper homeostasis of the intestine. Analysis of a newly established mouse model in which hedgehog (Hh) signals are blocked (Hhip transgenic mice) reveals that establishment of the crypt/villus axis requires this signaling pathway. Hh signals emanate from the epithelium and are received by the mesenchyme. Shh and Ihh participate in this signal;these two signaling proteins have both overlapping and separate roles. Loss of the combined Hh signal permits the formation of ectopic pre-crypt structures on villus tips, thus disrupting the normal organization of the crypt/villus axis. The epithelial phenotype of Hhip mice reflects alterations in cell:cell crosstalk between the epithelial cells and an expanded population of subepithelial myofibroblasts. The proposal tests the following Hypothesis: A combined Ihh and Shh signal from the epithelium is received by subepithelial myofibroblasts and acts indirectly to limit and organize the Wnt responsive epithelial pre-crypt compartment.
In Aim 1, the sequence of molecular and morphological events that accompany crypt/villus axis polarization during late intestinal development will be compared in wild type, Shh -/-, Ihh -/- and Hhip mice.
In Aim 2, the targets of Hh signaling in the mesenchymal compartment will be identified. Separate and common targets of Shh and Ihh will be sought;the possibility that Hh induces different genes at different concentrations will be tested. Finally, Aim 3 explores how Hh proteins function to organize the crypt/villus axis (i.e., by polarization via a morphogen gradient or by anchoring of the pre-crypt region) and tests specific candidate genes for their role in patterning this axis. The work will provide new insights into cell:cell signaling pathways crucial for intestinal development.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK065850-05
Application #
7579761
Study Section
Clinical and Integrative Gastrointestinal Pathobiology Study Section (CIGP)
Program Officer
Carrington, Jill L
Project Start
2005-04-01
Project End
2010-08-31
Budget Start
2009-04-01
Budget End
2010-08-31
Support Year
5
Fiscal Year
2009
Total Cost
$320,842
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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Gurdziel, Katherine; Lorberbaum, David S; Udager, Aaron M et al. (2015) Identification and Validation of Novel Hedgehog-Responsive Enhancers Predicted by Computational Analysis of Ci/Gli Binding Site Density. PLoS One 10:e0145225
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Whiteman, Eileen L; Fan, Shuling; Harder, Jennifer L et al. (2014) Crumbs3 is essential for proper epithelial development and viability. Mol Cell Biol 34:43-56
Walton, Katherine D; Kolterud, Asa (2014) Mouse fetal whole intestine culture system for ex vivo manipulation of signaling pathways and three-dimensional live imaging of villus development. J Vis Exp :e51817
Prakash, Ajay; Udager, Aaron M; Saenz, David A et al. (2014) Roles for Nkx2-5 and Gata3 in the ontogeny of the murine smooth muscle gastric ligaments. Am J Physiol Gastrointest Liver Physiol 307:G430-6
Liu, Hong Xiang; Ermilov, Alexandre; Grachtchouk, Marina et al. (2013) Multiple Shh signaling centers participate in fungiform papilla and taste bud formation and maintenance. Dev Biol 382:82-97
VanDussen, Kelli L; Carulli, Alexis J; Keeley, Theresa M et al. (2012) Notch signaling modulates proliferation and differentiation of intestinal crypt base columnar stem cells. Development 139:488-97
Walton, Katherine D; Kolterud, Asa; Czerwinski, Michael J et al. (2012) Hedgehog-responsive mesenchymal clusters direct patterning and emergence of intestinal villi. Proc Natl Acad Sci U S A 109:15817-22
Zacharias, William J; Madison, Blair B; Kretovich, Katherine E et al. (2011) Hedgehog signaling controls homeostasis of adult intestinal smooth muscle. Dev Biol 355:152-62

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