JNK is associated with Bcl-2 and PP1 in mitochondria: paclitaxel induces its activation and its association with the phosphorylated form of Bcl-2.

It has been shown that the activation of JNK after paclitaxel-induced microtubule damage is parallel to Bcl-2 phosphorylation, cell cycle arrest in mitosis and apoptosis. Using subcellular fractionation and immunocytochemistry, we found here that a pool of activated JNK is located in mitochondria of HeLa cells treated with paclitaxel. Furthermore, whereas the JNK protein is present in a tripartite complex with the anti-apoptotic Bcl-2 protein and the PP1 phosphatase in mitochondria isolated from control cells, the activated form of JNK was associated with the phosphorylated form of Bcl-2, but devoid of PP1, in mitochondria isolated from paclitaxel-treated cells.