Polycomb group (PcG) proteins comprise the Polycomb complexes PRC1 and PRC2 that regulate gene expression levels through histone modification. Although PRC1 and PRC2 are emerging to play important roles in cancer stem cells, their roles in neural stem/progenitor cells (NSPCs) are largely unknown. A new research led by Drs. LIU Chang-Mei and TENG Zhao-Qian from the State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, discovered that:

• MiR-203 is repressed by EZH2, a key PRC2 component, in both embryonic and adult NSPCs..
• MiR-203 negatively regulates self-renewal and proliferation of NSPCs, but promotes neuronal differentiation capacity.
• One of PRC1 components, Bmi1, is a direct downstream target of miR-203 in NSPCs.
• Conditional knockout Ezh2 results in decreased self-renewal and proliferation ability of both embryonic and adult NSPCs. Meanwhile ectopic overexpression of BMI1 rescues the self-renewal and proliferation deficiency exhibited by miR-203 overexpression in NSPCs.

As PcG proteins and microRNAs are usually co-expressed, these findings might have significant implications for other cell types or cancer tissues. This research entitled “MiR-203 Interplays with Polycomb Repressive Complexes to Regulate the Proliferation of Neural Stem/Progenitor Cells” has been published online in Stem Cell Reports.