미세먼지에 의한 상피세포 내 ERM 단백질의 탈인산화

Abstract

Abstract Particulate matter treatment on epithelial cell induces rapid dephosphorylation of ERM proteins

Ha, Young Eun Dept. of bioengineering The Graduate School Hanyang University

The ERM protein family consists of three closely related proteins, Ezrin, Radixin and Moesin. They are thought to have a role as general cross-linkers between plasma membranes and cytoskeletons. It had long been known that the ERM proteins phosphorylated on their C-terminal threonine residue are active in their cross-linking activity. More recently, the degree of ERM protein phosphorylation were found to relate to remodeling of microvilli in many cell types. Inhalation of particulate matter (PM) aggravates respiratory symptoms in patients with chronic airway diseases. PM induces alveolar epithelial cell DNA damage and apoptosis are known to be cellular and molecular mechanisms underlying the toxic pulmonary effects of PM. But the underlying mechanisms of this response remain poorly understood. Therefore, we adopted a proteomic technology to analyze the exact mechanism. Phosphoproteins in titanium dioxide (TiO2) treated epithelial cell were enriched by using the phospho-protein enrichment kit. Affinity-enriched proteins were separated on SDS-PAGE gels and Tryptic digested peptides from gels were analyzed by LC-ESI-MS/MS and results searched against public databases of human proteins. Proteome data were validated using the western blot. We established the animal model that was exposed for 1 hr after injection of titanium dioxide (TiO2) and silica dioxide (SiO2) particle through the trachea of Balb/c mice. The state of changed phosphoprotein by TiO2 particles in lung was estimated by western blot, immunohistochemical staining. In this study, the results indicated that treatment of epithelial cells with TiO2 and SiO2 particles altered about 200 phosphoproteins. Among them, we have chosen phosphorylated ERM proteins indicating dose-dependent decrease on proteome data. These data were validated by western blot analysis and the degree of ERM phosphorylation was decreased in PM treated epithelial cells compared with that of the non-treated. Dephosphorylation of ERM proteins was also observed in animal model. The expression of phosphorylated ERM proteins was definitely lower in lungs of PM treated mice than those in control mice. These results suggest that dephosphorylation of the ERM proteins is induced by the PM treatment. This process may be directly associated with phosphatase of regenerating liver-3 (PRL-3) working as a specific and direct cellular substrate of Ezrin from among a variety of phosphatases.