[ODP-157] Campylobacter jejuni recruit LC3 to bacterial invasion site on host cells through Rac1 signaling
Background: Campylobacter jejuni (Cj) causes gastroenteritis with entering into host intestinal epithelial cells. However, invasion-associated host cell signaling is poorly understood. Previously, we found association between autophagy signaling and Cj invasion. As a result, Cj accelerated bacterial entry by using autophagy signaling. Here we estimated the mechanism how autophagy is involved in Cj invasion, and found the association of autophagy in the classical Cj invasion signaling, especially actin polymerization factor, Rac1.
Method: To investigate the association between autophagy signaling and actin dynamics signaling in Cj invasion, constitutive active (CA) form and dominant negative (DN) form of Rho family small GTPase was expressed in HeLa cell. Intracellular bacterial cell number was estimated by gentamycin protection assay.
Results & Discussion: Cj invasion was increased in CA-Rac expressing cells, but it was canceled by autophagy inhibitor treatment. Additionally, autophagy-associated protein, LC3, was recruited to Cj in bacterial entry site, and this colocalization was frequently observed in CA-Rac expressed cell and attenuated in DN-Rac. It indicates that recruitment of LC3 to entering Cj was regulated by Rac activity. Our results suggest that autophagy, especially LC3 is involved in early stage of Cj invasion step through Rac1 signaling pathway.
Method: To investigate the association between autophagy signaling and actin dynamics signaling in Cj invasion, constitutive active (CA) form and dominant negative (DN) form of Rho family small GTPase was expressed in HeLa cell. Intracellular bacterial cell number was estimated by gentamycin protection assay.
Results & Discussion: Cj invasion was increased in CA-Rac expressing cells, but it was canceled by autophagy inhibitor treatment. Additionally, autophagy-associated protein, LC3, was recruited to Cj in bacterial entry site, and this colocalization was frequently observed in CA-Rac expressed cell and attenuated in DN-Rac. It indicates that recruitment of LC3 to entering Cj was regulated by Rac activity. Our results suggest that autophagy, especially LC3 is involved in early stage of Cj invasion step through Rac1 signaling pathway.