Intragenic deletion of Tgif causes defectsin brain development
Chenzhong Kuang1, Yan Xiao, Ling Yang
1Department of Medical and Molecular Genetics, Indiana University School of Medicine and the Walther Cancer Institute, Indianapolis, IN 46202, USA.
Human Molecular Genetics
|November 4, 2006
Summary
Targeted deletion of the Tgif gene in mice caused brain developmental defects, including holoprosencephaly (HPE). This Tgif deletion mouse model reveals genetic complexity in HPE pathogenesis.
Area of Science:
- Developmental biology
- Genetics
- Neuroscience
Background:
- TG-interacting factor (TGIF) is a transcriptional repressor involved in TGF-beta and retinoic acid signaling.
- Mutations in TGIF are linked to holoprosencephaly (HPE), a common congenital brain malformation.
- Previous studies with whole Tgif gene deletions in mice showed no brain defects.
Purpose of the Study:
- To investigate the role of Tgif in embryonic brain development.
- To establish a mouse model for studying HPE pathogenesis.
Main Methods:
- Generated mice with a targeted deletion of the third exon of the Tgif gene.
- Analyzed brain development in heterozygous and homozygous mutant mice.
- Examined expression of dorsal-ventral patterning genes (Shh, Pax6, Nkx2.2).
- Assessed cell proliferation in the ventricular neuroepithelium.
Main Results:
- Tgif exon 3 deletion caused a spectrum of brain defects, including exencephaly, microcephaly, and HPE, in both heterozygous and homozygous mice.
- Expression of key patterning genes was altered.
- Increased cell proliferation and tissue expansion were observed in the ventricular neuroepithelium.
- The incidence of brain abnormalities was dependent on the genetic background.
Conclusions:
- Targeted Tgif deletion, but not whole gene deletion, results in embryonic brain developmental defects.
- The Tgif deletion mouse model is valuable for studying HPE.
- Genetic modifiers likely interact with Tgif to influence HPE pathogenesis.
