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Functions of TGIF homeodomain proteins and their roles in normal brain development and holoprosencephaly
Author(s) -
Wotton David,
Taniguchi Kenichiro
Publication year - 2018
Publication title -
american journal of medical genetics part c: seminars in medical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 101
eISSN - 1552-4876
pISSN - 1552-4868
DOI - 10.1002/ajmg.c.31612
Subject(s) - holoprosencephaly , forebrain , biology , homeobox , sonic hedgehog , genetics , gene , haploinsufficiency , microbiology and biotechnology , transcription factor , neuroscience , phenotype , fetus , pregnancy , central nervous system
Holoprosencephaly (HPE) is a frequent human forebrain developmental disorder with both genetic and environmental causes. Multiple loci have been associated with HPE in humans, and potential causative genes at 14 of these loci have been identified. Although TGIF1 (originally TGIF, for Thymine Guanine‐Interacting Factor) is among the most frequently screened genes in HPE patients, an understanding of how mutations in this gene contribute to the pathogenesis of HPE has remained elusive. However, mouse models based on loss of function of Tgif1 , and the related Tgif2 gene, have shed some light on how human TGIF1 variants might cause HPE. Functional analyses of TGIF proteins and of TGIF1 single nucleotide variants from HPE patients, combined with analysis of forebrain development in mouse embryos lacking both Tgif1 and Tgif2 , suggest that TGIFs regulate the transforming growth factor ß/Nodal signaling pathway and sonic hedgehog (SHH) signaling independently. Although, some developmental processes that are regulated by TGIFs may be Nodal‐dependent, it appears that the forebrain patterning defects and HPE in Tgif mutant mouse embryos is primarily due to altered signaling via the Shh pathway.