Role of Interferon Regulatory Factor 6 (IRF6) in cell polarization
Interferon Regulatory Factor 6 (IRF6) is a gene that is expressed in epithelia, including keratinocytes of the epidermis. IRF6 has been shown to be required for keratinocyte cell migration as IRF6-deficient keratinocytes failed to close a scratch wound in vitro. Many cellular processes contribute to cell migration, including the polarization of the keratinocytes into a leading edge and a lagging tail. The movement of the cell is facilitated by disassembling the cytoskeleton in the lagging tail and its reassembling at the leading edge. The Golgi apparatus and microtubule organizing center (MTOC) play important roles in the movement of the cytoskeleton and hence in cell migration. Although typically found around the nucleus in a non-migrating cell, the golgi and MTOC move in front of the nucleus upon cellular directed migration, causing cell polarization.
We hypothesize that the lack of directed migration in IRF6 deficient keratinocytes is due to deficient cellular polarity. Immunofluorescence for markers of the Golgi apparatus and the MTOC using GM130 and gamma tubulin antibodies indicate strong staining around the nucleus (GM 130, specific to the Golgi) and in the MTOC (gamma tubulin) in non-migrating wild type human and mouse keratinocytes. The goal of the project was to extend these studies to IRF6 deficient keratinocytes, both of human and mouse origin. Different time points following scratch assay were evaluated to determine the spatiotemporal IRF6-dependent keratinocyte polarity. If IRF6 impacts movement of Golgi and the MTOC, we expect them to orient in front of the nucleus in the leading edge of the wild type cells and fail to orient properly in IRF6 deficient cells. However, the results were inconclusive as we did not see the expected polarization phenotype in wildtype leading to inconclusive results.