About Research
Epithelial cells are constitutively polarized to play fundamental functions such as vectorial transport. There are two membrane domains of epithelial cells, the apical membrane and basolateral membrane. These membrane domains are separated by cell adhesion apparatus. Most of our previous studies concerning epithelial polarity and cell adhesion have been focused on identification of new genes or elucidation of protein-protein interactions（for example, tricellulin of FRMD4A)
Although lipids are the main component of cells together with proteins, the functions of lipids or the physiological meaning of diversity of lipid species are not well elucidated. To analyze membrane lipids, we recently developed a new method to determine the lipid composition of plasma membrane (Ikenouchi et al. 2012).Taking advantage of this method, we succeeded in clarifying the difference of lipid composition between the apical membrane and the basolateral membrane and found that sphingomyelin plays essential roles in the formation of microvilli (Ikenouchi et al. 2013).
Furthermore, we identified several epithelial-cell specific lipids by comparing the lipid profile between epithelial cells and mesenchymal cells, taking advantage of previously established cell lines (Ikenouchi et al.2003).Currently we try to elucidate functional roles of these lipids by examining whether knock-down of biosynthetic enzymes in cultured epithelial cells affect epithelial polarity and cell-cell adhesion.
The aim of our study from the viewpoint of basic science is to clarify the importance of individual lipid species by using epithelial cells as an experimental model. The research purpose for clinical science is to find novel therapeutic targets in diseases correlated with epithelial-polarity disorders and epithelial-mesenchymal transition, such as cancer, polycystic kidney disease and pulmonary fibrosis.