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 years of funding, we have three Specific Aims. The First makes use of an extremely powerful in vitro system we have developed where we can maintain limb bud cells in an undifferentiated state for several weeks and still reconsitute them as a limb bud and assess their morphological potential. We will use this to study the integration of time and dose in establishing threshold responses to Shh activity in patterning the limb and also study how various signals work together to define proximodistal limb pattern.
A second Aim focuses on the role of Shh in controlling the size ofthe limb bud and its synergistic activity with the Hippo/YAP pathway. This part ofthe project will be carried out in mice, using activatable and conditionally deficient alleles of YAP. Mice harboring these alleles will be bred to lines of mice expressing cre recombinase exclusively in the Shh-expressing cells, throughout the limb bud, and in the limb myoblasts, thereby activating or inactivating the YAP/HIPPO pathway specifically in these tissues. Finally, a third Aim will address the important, but poorly understood phenomonom of scaling, wherein the same signaling systems pattern very small or large embryos in an equivelant manner. We will focus on the mechanisms interpreting Shh signaling in the relatively large limb bud of the chick in comparison to the relatively small 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 #
5R37HD032443-20
Application #
8680265
Study Section
Special Emphasis Panel (NSS)
Program Officer
Javois, Lorette Claire
Project Start
1995-04-01
Project End
2015-05-31
Budget Start
2014-06-01
Budget End
2015-05-31
Support Year
20
Fiscal Year
2014
Total Cost
$553,611
Indirect Cost
$220,214
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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Rodrigues, Alan R; Yakushiji-Kaminatsui, Nayuta; Atsuta, Yuji et al. (2017) Integration of Shh and Fgf signaling in controlling Hox gene expression in cultured limb cells. Proc Natl Acad Sci U S A 114:3139-3144
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Rodrigues, Alan R; Tabin, Clifford J (2013) Developmental biology. Deserts and waves in gene expression. Science 340:1181-2

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