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Targeted disruption of Tgif, the mouse ortholog of a human holoprosencephaly gene, does not result in holoprosencephaly in mice.

ABSTRACT: 5'-TG-3'-interacting factor or transforming growth factor beta (TGF-beta)-induced factor (TGIF) belongs to a family of evolutionarily conserved proteins that are characterized by an atypical three-amino-acid loop extension homeodomain. In vitro studies have implicated TGIF as a transcriptional repressor and corepressor in retinoid and TGF-beta signaling pathways that regulate several important biological processes. Heterozygous nonsense and missense mutations of the human TGIF gene have been associated with holoprosencephaly, the most common congenital malformation of the forebrain. In mice, Tgif mRNA is expressed ubiquitously in the ventricular neuroepithelium at embryonic day 10.5 (E10.5) but displays a medial to lateral gradient in the developing cerebral cortex at E12.5. The expression quickly declines by E14.5. The spatiotemporal expression profile of Tgif is consistent with its involvement in midline forebrain development. To better understand the function of Tgif in forebrain patterning and proliferation in vivo, we generated mice lacking Tgif by targeted deletion of exons 2 and 3, which encode 98% of the amino acids. Tgif(-)(/)(-) mice had no detectable Tgif protein by Western blotting. Surprisingly, however, these mice were viable and fertile. In addition, there were no discernible derangements in any of the major organ systems, including the forebrain. Overall our results point to a possible functional redundancy of Tgif, potentially provided by the closely related Tgif2.

SUBMITTER: Shen J

PROVIDER: S-EPMC1084278 | biostudies-literature | 2005 May

REPOSITORIES: biostudies-literature

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Targeted disruption of Tgif, the mouse ortholog of a human holoprosencephaly gene, does not result in holoprosencephaly in mice.

Shen Jun J Walsh Christopher A CA

Molecular and cellular biology 20050501 9

5'-TG-3'-interacting factor or transforming growth factor beta (TGF-beta)-induced factor (TGIF) belongs to a family of evolutionarily conserved proteins that are characterized by an atypical three-amino-acid loop extension homeodomain. In vitro studies have implicated TGIF as a transcriptional repressor and corepressor in retinoid and TGF-beta signaling pathways that regulate several important biological processes. Heterozygous nonsense and missense mutations of the human TGIF gene have been ass ...[more]

PMID: 15831469

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Project description:Holoprosencephaly (HPE), which results from failed or incomplete midline forebrain division early in gestation, is the most common forebrain malformation. The etiology of HPE is complex and multifactorial. To date, at least 12 HPE-associated genes have been identified, including TGIF (transforming growth factor beta-induced factor), located on chromosome 18p11.3. TGIF encodes a transcriptional repressor of retinoid responses involved in TGF-? signaling regulation, including Nodal signaling. TGIF mutations are reported in approximately 1-2% of patients with non-syndromic, non-chromosomal HPE. We combined data from our comprehensive studies of HPE with a literature search for all individuals with HPE and evidence of mutations affecting TGIF in order to establish the genotypic and phenotypic range. We describe 2 groups of patients: 34 with intragenic mutations and 21 with deletions of TGIF. These individuals, which were ascertained from our research group, in collaboration with other centers, and through a literature search, include 38 probands and 17 mutation-positive relatives. The majority of intragenic mutations occur in the TGIF homeodomain. Patients with mutations affecting TGIFrecapitulate the entire phenotypic spectrum observed in non-chromosomal, non-syndromic HPE. We identified a statistically significant difference between the 2 groups with respect to inheritance, as TGIF deletions were more likely to be de novo in comparison to TGIF mutations (?(2) ((2)) = 6.97, p(permutated) = 0.0356). In addition, patients with TGIF deletions were also found to more commonly present with manifestations beyond the craniofacial and neuroanatomical features associated with HPE (p = 0.0030). These findings highlight differences in patients with intragenic mutations versus deletions affecting TGIF, and draw attention to the homeodomain region, which appears to be particularly relevant to HPE. These results may be useful for genetic counseling of affected patients.

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Dataset Information

Targeted disruption of Tgif, the mouse ortholog of a human holoprosencephaly gene, does not result in holoprosencephaly in mice.

Publications

Targeted disruption of Tgif, the mouse ortholog of a human holoprosencephaly gene, does not result in holoprosencephaly in mice.

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