Thereby, suggesting that activation of EGFR through 1-integrin as a possible mechanism for bacteria mediated induction of EGR1. originating from the natural site of the infection, suggesting that the EGR1 induction is cell type specific. Finally, we show that EGFRCERK1/2 and 1-integrin signaling are the main pathways used for bacteria-mediated EGR1 upregulation. In conclusion, the increase of EGR1 expression in epithelial cells is a common stress induced, cell type specific response upon host-bacteria Oleuropein interaction that is mediated by EGFRCERK1/2 and 1-integrin signaling. (Abdel-Latif et al., 2004; Howie et al., 2005; Rupp et al., 2005; Schubert-Unkmeir et al., 2007; Maekawa et al., 2010; Susilowati et al., 2011). Some of these studies have identified ERK as an important signaling molecule, but additional information on the mechanisms underlying bacterial EGR1 induction and its role in virulence is very scarce. However, for it has been shown that epidermal growth factor receptor (EGFR) transactivation is partially involved and an intact Cag secretion system is necessary (Keates et al., 2005). For the enterobacteriaceae family members serovar Typhimurium, EGR1 induction is type III secretion system dependent (de Grado et al., Oleuropein 2001; Hannemann et al., 2013; Kwuan et al., 2013). The first step in bacterial pathogenesis is the colonization of the Oleuropein infection site through active adherence of pathogens to specific tissues. Bacterial adherence to the host epithelia generally depicts a receptor-ligand model. The bacterial adhesins act as a ligand that binds to specific receptors on the host epithelia. Colonization may not necessarily result in invasion or an inflammatory response. Host-pathogen interaction is a dynamic phenomenon; additional information about the early events that occur during host-pathogen interaction can provide new insights on bacterial virulence and pathogenicity. Although the role of EGR1 as an immediate early response factor is well established in the regulation of inflammatory and immune responses, there is limited information on whether EGR1 induction is a general response by host cells upon infection by all bacteria or a response specific for a particular bacterial strain. Also, the exact molecular pathway followed by each bacterium to induce EGR1 is not known. Therefore, the current study sought to determine whether bacterial adherence induces EGR1, whether the induction is common or specific to a selected group of bacteria, the molecular mechanisms involved and the role of EGR1 in bacterial adherence. We show that most bacteria can upregulate EGR1 in host epithelial cells, independent of the level of adherence, Gram-staining type and pathogenicity. Moreover, EGR1 upregulation is a cell type specific phenomenon, and is dependent on bacterial viability and host cell contact. Furthermore, the main pathways utilized by bacteria to trigger EGR1 expression are EGFRCERK1/2 and 1-integrin signaling. Materials and methods Bacterial strains and culture conditions All bacterial strains used in this study are listed in Table ?Table1.1. All strains and strains were grown on GC agar (Acumedia) containing Kellogg’s supplement (Kellogg et al., 1963). strains and the strains were grown on Luria agar (Acumedia). The strains were grown on Rogosa agar (Oxoid). All aforementioned bacteria were cultured at 37C and 5% CO2 for 16C18 h before experimentation. The strains were grown on Colombia blood agar (Acumedia) supplemented with 5% defibrinated horse blood and 5% inactivated horse serum (H?tunalab) for 3 days at 37C under microaerophilic conditions (5% O2, 10% CO2). Before each experiment, the bacteria were washed once and resuspended in cell culture medium without serum that was specific to the cell line that was used. Table 1 Bacterial strains used in this study. serogroup A Z2491NsGN01 (Jonsson et al., 1991)Nm-Bserogroup B MC58NlNCTC 10618 (Jonsson et al., 1991)Nm-Cserogroup C FAM20 (Rahman et al., 1997)Nm-Wserogroup W-135 JB515 (Rahman et al., 1997)PaPAO1Sp-M1serogroup M1 S340LrATCC PTA5289Sp-M3serogroup M3 S208LsLMG9477Sp-M5serogroup M5 Manfredo (Johnsson et al., 1998)Sp-M6serogroup M6 S165 (Sj?linder et al., 2008)SaNewmanStomach (AGS)Hp-J99J99 (ATCC 700824)LrhKx151A1 (Roos et al., 2005)Hp-672167:21 (Bj?rkholm et al., 2001)Intestine (Caco-2)Ec-B09B09-11822 (Skorup et al., 2014)Lrh-GGGG (ATCC 53103)Ec-O11O111:B4Ec-DH5DH5SE-3934serovar Enteritidis 3934STM-42serovar Typhimurium FIA42Urogenital tract (ME180)NgMS11 (ATCC BAA1833)LcMV24-1a Open in a separate window Cell lines Rabbit polyclonal to SGSM3 and culture conditions The human pharyngeal epithelial cell line FaDu (ATCC HTB-43),.