Oral Presentations - Pathology and Laboratory Medicine - University ...

OtherAbstract # 71Mary Zhang, Xin Ye, Gomaa MH Hemida, Stefanie Mak and Decheng YangDepartment of Pathology and Laboratory Medicine, University of British Columbia,Heart + Lung Institute + St. Paul’s Hospital, Vancouver, CanadaMary Zhangcoxsackievirus b3-induced downregulation of p58ipk isinvolved in shifting endoplasmic reticulum stress tocell apoptosisBackround/ObjectivesUnfolded (or misfolded) protein responses (UPR) are linked to occurrences of many pathological disorders, such asneuron degeneration, cystic fibrosis, diet-induced obesity, type 2 diabetes and virus-induced diseases. CoxsackievirusB3 (CVB3) is a common pathogen of viral myocarditis in children and young adolescents and its infection can triggerendoplasmic reticulum (ER) stress-mediated UPR. p58IPK is one of the signaling molecules that are involved inthe UPR pathway. It is a negative regulator of eIF2a signaling in cellular mRNA translation process. Although theinteractions between p58IPK and other signaling proteins have been determined in previous studies, the functionalrole of p58IPK during CVB3 infection has not been examined. Our previous investigations have demonstrated thatCVB3 infection induced cell apoptosis and also decreased production of p58IPK. However, the connection of thesetwo events has not been elucidated.Methods and ResultsIn this study, HeLa cells are either stably transfected with a p58IPK plasmid to over-express p58IPK or treated withspecific siRNAs to silence the p58IPK expression. These cells are then infected with CVB3 at a MOI of 10 and usedto perform a set of analyses after incubation for different periods of time. Based on the MTS cell viability assay anddetection of activation of caspse-3, p58IPK-transfected HeLa cells showed a higher survival rate and lower productionof activated caspase-3 than the empty vector-transfected control cells after CVB3 infection, which suggest that p58IPKplays a role in pro-survival and anti-apoptosis process. Moreover, Western Blot analysis of these cell lysates showed ahigher expression level of viral protein VP1 and more production of CVB3 particles in p58IPK expressing cells than inthe control cells. In contrast, silencing of p58IPK by specific siRNA transfection decreased cell survival rate, sensitizedthese cells to CVB3-induced apoptosis, and eventually led to a lower expression level of VP1 as compared to thescrambled siRNA-transfected control cells as well as the non-transfected HeLa cells. Since CVB3 infection of nontransfetcedHeLa cells also downregulated p58IPK expression and up-regulated ER stress marker, the glucose regulatedprotein 78 (GRP78), our data indicates that persistent CVB3 infection will eventually induce cell death.Conclusionp58IPK, as an ER co-chaperone, plays an important role in pro-survival and anti-apoptosis. During CVB3 infection,the virus-induced ER stress responses lead to the downregulation of p58IPK expression and thus result in the transitionfrom pathway of pro-survival to pro-apoptosis.82 2 0 1 0 * P o s t e r P r e s e n t a t i o n s