PROJECT SUMMARY
Over 70 million surgeries are performed in the United States annually. Although many wounds heal without
problem, half require postsurgical wound care. Wounds that do not heal affect about 7 million people annually
and generate treatment costs of about $100 billion, which creates a significant financial burden on the US
economy. Increasing our understanding of the molecular pathways regulating wound healing would enhance
tissue repair and reduce healthcare costs.
Our long-term goal is to identify molecular pathways regulating tissue repair. We previously demonstrated
that the transcription factor Interferon Regulatory Factor 6 (IRF6) is required for proper wound healing by acting
as a master regulator of keratinocyte differentiation, proliferation, and collective cell migration. Our recent
preliminary data show that Irf6-deficient keratinocytes have weaker cell-cell adhesion, and reduced membrane
localization of adherens junction components, including E-cadherin, providing a potential rationale for the IRF6-
dependent keratinocyte migration defect. Interestingly, our preliminary data also revealed that total adherens
junction protein levels were not changed, suggesting a non-transcriptional function of IRF6 in these processes.
IRF6, as a member of the Interferon regulatory transcription factor family, contains a highly conserved N-
terminal, DNA-binding domain, and a less conserved protein interaction domain. Most of IRF6 described
functions have been associated with its transcriptional activity, and very little is known about the functions of its
protein interaction domain. Particularly, which domain of IRF6 contributes to cell-cell adhesions required for
wound healing, is unknown. Our central hypothesis is that IRF6 promotes collective cell migration via a non-
transcriptional regulation of cell-cell adhesion molecules at the cytoplasmic membrane. We will test our central
hypothesis with the execution of two aims. In Aim 1 we will determine how IRF6 regulates E-cadherin trafficking.
In Aim 2 we will determine how IRF6 promotes collective cell migration. To test our hypothesis, using a wide
range of biochemical and cellular assays, we will take advantage of multiple IRF6 mutant lines to determine
which domains of this transcription factor are required for regulating cell adhesions. The same mutant cell lines
will be used to perform scratch wounds in 2D and excisional wounds in 3D models which will shed light on the
importance of each domain of IRF6 in collective cellular migration.
At the completion of this study, we will have identified a novel mechanism by which this transcription factor
regulates vesicular trafficking necessary for cell adhesion organization, which could provide a molecular
mechanism for the increased risk of surgical complications observed in patients with IRF6 mutations.