Skeletal muscles are comprised of two major cell types, slow and fast, that have distinct physiological, biochemical, morphological and developmental properties. The long-term goals of this work are to understand the mechanisms that regulate the formation and patterning of these different muscle types and how these mechanisms are altered in muscular diseases. Previous studies of zebrafish embryos have suggested that Hedgehog (Hh) produced by notochord and floor plate acts locally to specify slow muscle. Even though muscle precursor cells throughout the somite are apparently competent to respond to Hh, only a single monolayer precisely adjacent to the source of Hh, forms slow muscle. The proposed studies will use embryological and genetic methods to test a new hypothesis that accounts for this remarkably precise patterning: Two mechanisms limit the inductive action of Hh to immediately adjacent cells. First, notochord induces a subset of muscle precursors, in an Hh independent manner, to form adaxial cells, an epithelial monolayer that blankets the notochord. Then, in response to Hh signaling, cells in this monolayer express high levels of Patched and Hedgehog interacting protein that bind Hh at high affinity and limit its action. Thus, adaxial cells adjacent to the notochord receive high levels of Hh that induces them to become slow muscle, while at the same time, they reduce Hh signaling to more lateral cells that consequently form fast muscle.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
2R01AR045575-06A1
Application #
6819633
Study Section
Special Emphasis Panel (ZRG1-DEV-1 (01))
Program Officer
Nuckolls, Glen H
Project Start
1999-02-05
Project End
2009-04-30
Budget Start
2004-07-01
Budget End
2005-04-30
Support Year
6
Fiscal Year
2004
Total Cost
$338,975
Indirect Cost
Name
University of Oregon
Department
Neurosciences
Type
Schools of Arts and Sciences
DUNS #
948117312
City
Eugene
State
OR
Country
United States
Zip Code
97403
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