Figure 8: Working model of the pathways mediating apoptosis versus axon pruning.
From: Distinct pathways mediate axon degeneration during apoptosis and axon-specific pruning
Proteins highlighted in yellow have been shown to be required for both apoptosis and axon pruning pathways. Our results indicate that Apaf-1 and Caspase-6 (highlighted in blue) are two points of divergence. Future experiments will be required to determine what role, if any, is played by the mitochondria and cyt c release in axon-selective degeneration. In addition, how Caspase-9 is able to activate Caspase-6 and Caspase-3 without Apaf-1 remains to be determined. While Caspase-6 and Caspase-3 are both required for axon pruning, their exact order of activation during axon pruning in neurons is still unclear.
