Fig. 6

TTP regulates a pro-apoptotic JNK pathway via targeting DUSP1. a Phosphorylation of TTP allows expression of the ARE-bearing mRNA of DUSP1 that inhibits JNK and hence blocks JNK-mediated apoptosis. JNK pathway is blocked by the inhibitor JNK-IN-8. b–d Effect of TTP-AA mutant on DUSP1 and phosphorylation of JNK. BMDM TTP-deficient cells were treated with doxycycline to express TTP-AA and TTP wild-type prior to AraC treatment. b DUSP1 mRNA level was measured by qPCR and is shown relative to GAPDH mRNA. c Western analyses of TTP, DUSP1, and phospho-JNK are shown. d TTP-AA (GFP tagged) was immunoprecipitated with GFP antibody, followed by qPCR analysis for DUSP1 mRNA. e Western analyses in THP1 and MOLM13 cells treated with indicated drug combinations for 1 day (150 μg/ml PFD and 2.5 μM LY2228820, which are half the amounts used in Figs. 4g and 5f). Phospho-TTP is indicated with an arrow and quantitation of TNFα protein is shown below. f JNK pathway mediates apoptosis. MOLM13 cells treated with indicated drug combinations. JNK pathway was inhibited with 1 μM JNK-IN-8. Western analyses of phospho-JNK, phospho-c-Jun, and c-Jun shown on the left; associated cell viability and death graphed on the right. Data are represented as average ± SEM