Polycomb protein family member CBX7 regulates intrinsic axon growth and regeneration

Neurons in the central nervous system (CNS) lose their intrinsic ability and fail to regenerate, but the underlying mechanisms are largely unknown. Polycomb group (PcG) proteins, which include PRC1 and PRC2 complexes function as gene repressors and are involved in many biological processes. Here we report that PRC1 components (polycomb chromobox (CBX) 2, 7, and 8) are novel regulators of axon growth and regeneration. Especially, knockdown of CBX7 in either embryonic cortical neurons or adult dorsal root ganglion (DRG) neurons enhances their axon growth ability. Two important transcription factors GATA4 and SOX11 are functional downstream targets of CBX7 in controlling axon regeneration. Moreover, knockdown of GATA4 or SOX11 in cultured DRG neurons inhibits axon regeneration response from CBX7 downregulation in DRG neurons. These findings suggest that targeting CBX signaling pathway may be a novel approach for promoting the intrinsic regenerative capacity of damaged CNS neurons.