Saethre-Chotzen syndrome (SCS) is a commonly inherited disorder predisposing humans to premature fusion of the skull calvarial bones (craniosynostosis) and a variety of limb defects. Greater than 45 percent of SCS patients have loss-of-function mutations in one copy of the Twist gene, making Twist haploinsufficiency a causative factor for SCS. Mice also show haploinsufficiency for Twist, as Twist heterozygotes exhibit craniofacial defects and toe duplications. Twist is a well-conserved basic helix-loop-helix (bHLH) protein essential for embryonic development in Drosophila and mouse. Its loss-of-function phenotypes in the limbs suggest that Twist normally has important patterning functions during limb development, interestingly, published and preliminary data show that overexpression of another bHLH protein essential for limb development, HAND2, causes phenotypes resembling those seen in SCS patients and in mice haploinsufficient for Twist. Because HAND2 gain-of-function phenocopies Twist loss-of-function, we hypothesize that HAND2 and Twist interact antagonistically during limb development. We will test for a genetic interaction between the two genes using simultaneous loss-of-function and simultaneous gain-of-function assays in both mouse and chick. In addition, we will use biochemical assays to determine the molecular mechanism behind the interaction between HAND2 and Twist.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31DE014516-03
Application #
6649180
Study Section
Special Emphasis Panel (ZRG1-CDF-6 (20))
Program Officer
Jackson, Lorrayne
Project Start
2002-09-01
Project End
2005-08-31
Budget Start
2003-09-01
Budget End
2004-08-31
Support Year
3
Fiscal Year
2003
Total Cost
$34,584
Indirect Cost
Name
Columbia University (N.Y.)
Department
Genetics
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032