TGIF, a gene associated with human brain defects, regulates neuronal development.
5'-TG-3'-interacting factor (TGIF) is an atypical homeo-domain protein. In vitro studies have shown that TGIF can repress transcription mediated by either of two signaling pathways: TGF-beta and retinoic acid signaling. Mutations in TGIF have been detected in patients with holoprosencephaly (HPE), a severe brain malformation associated with mental retardation. Thus, TGIF must play an essential role in nervous system development. However, the precise function of TGIF during vertebrate neural development is unknown. To investigate the in vivo role of TGIF, we overexpressed TGIF in the developing chick neural tube. Overexpressed TGIF decreased expression of specific genes expressed in dorsally restricted domains of the neural tube, including Cath1, Ms x 2, Pa x 6, and Wnt1. In contrast, the expression of other transcription factors, including those necessary for ventral fate such as Nk x 2.2, was not affected. Furthermore, a missense mutation in TGIF identified in an HPE patient disrupted the activity of TGIF. In addition, the related protein TGIF2 did not demonstrate the same activity as TGIF. Our data suggest that TGIF plays an important role in regulating the expression of genes expressed in specific dorsal-ventral domains during neural development.
Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Jessica L
JL
Knepper
Alison C
AC
James
Jeffrey E
JE
Ming
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001921:Brain / Q000002:abnormalities* / Q000196:embryology*; D019556:COS Cells; D002642:Chick Embryo; D002522:Chlorocebus aethiops; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D016142:Holoprosencephaly / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013116:Spinal Cord / Q000196:embryology
D018398:Homeodomain Proteins; D012097:Repressor Proteins; C097504:TGIF1 protein, human