Disrupted IRF6-NME1/2 Complexes as a Cause of Cleft Lip/Palate

Area of Science:

• Genetics and Developmental Biology
• Molecular Cell Biology

Background:

• Mutations in interferon regulatory factor 6 (IRF6) are linked to cleft lip/palate (CLP).
• IRF6 function is influenced by its cytoplasmic localization and regulated nuclear import.
• Understanding IRF6's protein interactions is key to elucidating its role in CLP pathogenesis.

Purpose of the Study:

• To identify direct protein interactors of IRF6.
• To investigate the functional consequences of IRF6 interactions with identified partners in the context of CLP.

Main Methods:

• Yeast 2-hybrid screens and co-immunoprecipitation assays to identify IRF6 interactors.
• Co-localization studies in primary palatal epithelial cells.
• Analysis of protein interactions and GTPase activation in response to IRF6 mutations.

Main Results:

• NME1 and NME2 were identified as direct IRF6 binding partners.
• IRF6 and NME proteins co-localize in the cytoplasm; interaction is enhanced by IRF6 phosphorylation.
• CLP-associated IRF6 mutations impair NME binding and increase Rac1/RhoA activation.
• Novel NME1/2 mutations were found in CLP patients, disrupting IRF6 interaction.

Conclusions:

• Cytoplasmic IRF6 regulates NME1/2 complex localization and function.
• Disruption of the IRF6-NME1/2 interaction contributes to CLP by affecting epithelial dynamics.
• NME proteins are potential novel genetic factors in CLP development.