Redistribution of EGF Receptor and α5, β1 Integrins in Response to Infection of Epithelial Cells by Serratia proteamaculans

Abstract

Eukaryotic cells use surface receptors to interact with the environment. Interacting with the cell receptors, pathogenic and opportunistic bacteria can invade cells that normally do not phagocytize. Bacteria Serratia proteamaculans can invade eukaryotic cells, and this ability correlates with the proteolytic activity of the actin-specific protease protealysin (Tsaplina et al., 2009). However, cellular receptors involved in the mechanism by which these bacteria penetrate the cells are not known. Bacterial outer membrane protein OmpX which is one of the substrates of protealysin is known to interact with EGF receptor and fibronectin. Therefore, in this work, changes in the localization of EGF receptors and fibronectin receptors α5, β1 integrins were monitored in the epithelial M-HeLa and A549 cells infected by bacteria S. proteamaculans. It turned out that in response to the infection α5 and β1 integrin subunits accumulate on the surface of M-HeLa cells, and bacteria attach intensively at the sites of the α5 integrin localization. The α5 integrin was not detected in A549 cells. The β1 integrin, localized evenly along the cell perimeter, accumulated in the cytoplasm in response to contact with bacterial cells, while the EGF receptor formed granules in the cytoplasm in response to invasion. A similar redistribution of EGF receptors occurs in response to EGF binding. These results indicate that invasion of S. proteamaculans into the epithelial cells of different origin occurs as a result of their interaction with different surface receptors.