PROJECT SUMMARY
Each year in the United States, more than 2,500 babies are born with a cleft palate (CP). CP is caused by
disruption of palatogenesis during embryonic development. This proposal aims to delineate critical molecular
pathways of palatogenesis, which will lead to development of better methods for diagnosis, treatment and
prevention of issues associated with CP.
MLL4 (aka KMT2D) is a histone H3-lysine 4 methyltransferase that creates transcriptionally active open
chromatin marks. Together with other subunits, such as UTX (aka KDM6A), MLL4 forms a complex (MLL4-C),
which functions as an important “epigenetic” transcriptional coactivator that triggers cell type-specific target
gene expression. Mutations in the MLL4 gene, as well as the UTX gene, cause the human developmental
disorder Kabuki syndrome (KS), which is characterized by craniofacial abnormalities, including CP.
We discovered that conditional knockout (cKO) mice with neural crest cell (NCC)-specific deletion of Mll4
develop various KS-like craniofacial phenotypes, including 100% penetrance for CP. These results suggest
that the loss of cell autonomous actions of MLL4 in the developing palatal mesenchyme results in CP and
other craniofacial structural defects of KS. Thus, we hypothesize that dysregulation of the MLL4-C-dependent
gene regulatory program leads to developmental and cellular deficits during palate development, resulting in
CP observed in Mll4-cKO mice and human KS. To test our hypothesis, we will pursue two specific aims: Aim 1,
to characterize the phenotype of cleft palate defect in Mll4-deficient mice; Aim 2, to define the mechanisms by
which Mll4-C regulates palatogenesis. Building on our strong preliminary data from a unique mouse model that
develops CP with 100% penetrance, this proposal will greatly advance our understanding of palatogenesis and
CP pathogenesis..