The general goal of this project is to understand patterning and morphogenesis during vertebrate embryogenesis,using Sonic hedgehog (Shh) signaling in the limb bud as a model. Building on the results of the previous five yearsof funding, we have three Specific Aims. The First makes use of an extremely powerful in vitro system we havedeveloped where we can maintain limb bud cells in an undifferentiated state for several weeks and still reconsitutethem as a limb bud and assess their morphological potential. We will use this to study the integration of time anddose in establishing threshold responses to Shh activity in patterning the limb and also study how various signalswork together to define proximodistal limb pattern.
A second Aim focuses on the role of Shh in controlling thesize ofthe limb bud and its synergistic activity with the Hippo/YAP pathway. This part ofthe project will becarried out in mice, using activatable and conditionally deficient alleles of YAP. Mice harboring these alleles willbe bred to lines of mice expressing cre recombinase exclusively in the Shh-expressing cells, throughout the limbbud, and in the limb myoblasts, thereby activating or inactivating the YAP/HIPPO pathway specifically in thesetissues. Finally, a third Aim will address the important, but poorly understood phenomonom of scaling, whereinthe same signaling systems pattern very small or large embryos in an equivelant manner. We will focus on themechanisms interpreting Shh signaling in the relatively large limb bud of the chick in comparison to the relativelysmall limb bud of the direct developing frog coqui.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37HD032443-16
Application #
8034091
Study Section
Special Emphasis Panel (NSS)
Program Officer
Javois, Lorette Claire
Project Start
1995-04-01
Project End
2015-05-31
Budget Start
2010-06-01
Budget End
2011-05-31
Support Year
16
Fiscal Year
2010
Total Cost
$610,351
Indirect Cost
Name
Harvard University
Department
Genetics
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115
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Wong, Siew Fen Lisa; Agarwal, Vikram; Mansfield, Jennifer H et al. (2015) Independent regulation of vertebral number and vertebral identity by microRNA-196 paralogs. Proc Natl Acad Sci U S A 112:E4884-93
Tschopp, Patrick; Sherratt, Emma; Sanger, Thomas J et al. (2014) A relative shift in cloacal location repositions external genitalia in amniote evolution. Nature 516:391-4
Cooper, Kimberly L; Sears, Karen E; Uygur, Aysu et al. (2014) Patterning and post-patterning modes of evolutionary digit loss in mammals. Nature 511:41-5
Rodrigues, Alan R; Tabin, Clifford J (2013) Developmental biology. Deserts and waves in gene expression. Science 340:1181-2

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