Figure 6.

Blockade of the ubiquitin-proteasome pathway attenuates protein degradation and necroptotic signaling triggered by TAK1 inhibition. (a) Western blots for the indicated proteins from extracts of wild-type MEF treated with vehicle control or 5z-7 plus TNFα for 4 h, in the presence of Nec-1, MG-132 (MG), lactacystin (Lac), or PYR-41 (PYR). * Indicates protein degradation. (b) Western blots for the indicated proteins after IP with an anti-RIP3 antibody from extracts of cells treated as in a for 1 h. (c) Caspase 8 activity in cells treated as in a for 2 h. ^†P<0.01 versus Con; ^#P<0.05 versus 5z-7 plus TNF. (d) Cell death assessed by PI staining in cells treated as in a for 4 h. ^†P<0.01 versus Con; ^#P<0.05 versus 5z-7 plus TNF. (e) Proposed model: TAK1 functions as nodal regulator of apoptosis and necroptosis by regulating multiple cell death checkpoints