RNF26 protects MITA from K48-linked polyubiquitination and degradation.

Abstract

<p>(A) Effects of RNF26 knockdown on virus-induced polyubiquitination of endogenous MITA. The THP-1-RNF26-RNAi or control cells (2×10⁷) were infected with SeV or HSV-1 for the indicated time points or left uninfected. Cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-Ub(K48) (upper panel), anti-Ub(K63) (middle panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins. (B) Effects of RNF5 knockdown on virus-induced K11-linked polyubiquitination of endogenous MITA. The 293-HA-Ub-K11O cells (2×10⁷) were transfected with the indicated RNAi plasmid (10 µg each). Twelve hours after transfection, the cells were selected with puromycin (1 µg/mL) for twenty-four hours and infected with SeV for the indicated time points or left uninfected. Cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated antibodies. (C) RNF26 and RNF5 competed with each other on MITA polyubiquitination. The 293 cells (5×10⁶) were transfected with MITA (5 µg), Flag-Ub-K48O and HA-Ub-K11O (1 µg each) together with indicated amount of RNF26 and RNF5. Twenty-four hours after transfection, cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-Flag (upper panel), anti-HA (middle panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins. (D) Effects of RNF26 knockdown on virus-triggered MITA degradation. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with SeV or HSV-1 for the indicated time points or left uninfected. Cells were lysed and whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins (upper immunoblots). The relative protein levels of MITA in reference to β-actin were analyzed by Quantity One program and data shown are mean ± S.D. of three independent experiments (lower histographs).</p