Proteomic Profiling of the TRAF3 Interactome Network Reveals a New Role for the ER-to-Golgi Transport Compartments in Innate Immunity

van Zuylen, Wendy J.; Doyon, Priscilla; Clément, Jean-François; Khan, Kashif Aziz; D'Ambrosio, Lisa M.; Dô, Florence; St-Amant-Verret, Myriam; Wissanji, Tasheen; Emery, Gregory; Gingras, Anne-Claude; Meloche, Sylvain; Servant, Marc J.

Next we examined the effect of reducing the expression level of Sec16A or p115 on the ability of TRAF3 to colocalize with MAVS upon SeV infection. As expected, TRAF3 localization reorganized into punctate structures following SeV infection, allowing a significant proportion of TRAF3 to colocalize with MAVS ( Figure 6A , panel 2). This effect was severely compromised by reducing the expression of Sec16A or p115 ( Figure 6A , compare panels 4 and 6 with panel 2). Additionally, co-immunoprecipitation experiments revealed that TRAF3 formed an immunocomplex with MAVS upon SeV infection. Interestingly, silencing the expression level of p115 or Sec16A clearly blunted the ability of TRAF3 to bind to MAVS upon SeV infection ( Figures 6B and 6C ). Thus loss-of-function experiments targeting p115 and Sec16A led to a mislocalization of TRAF3 and its subsequent incapacity to associate with MAVS upon RLH pathway activation.