EZH2 plays an important normal role in a variety of biological processes. "EZH2 is crucial to embryonic development because it turns genes off and on to guide the differentiation of embryonic stem cells into tissues and organs," Hung said. Embryonic stem cells can turn into any type of cell.

In a separate set of experiments, the researchers demonstrated that phosphorylation of EZH2 is necessary to the production of bone cells (osteoblasts).

Mesenchymal stem cells can differentiate into bone, cartilage or fat cells. The team showed only those cells with EZH2 phosphorylated by CDK1 differentiated into bone cells. Genes crucial to bone formation were silenced by methlyation but awakened when CDK1 altered EZH2.

A genomewide screen to identify genes targeted by EZH2 in mesenchymal stem cells was conducted before and after the cells differentiated into bone cells. Before, more than 4,000 genes were found to bind to EZH2. After differentiation to bone cells, 30 or fewer genes bound to the protein.

"This and other recently reported studies open up drug development possibilities by either inhibiting the methyltransferase activity of EZH2 or regulating phosphorylation to indirectly regulate EZH2's activity," Hung said.

"This study also suggests a possible way to induce mesenchymal stem cell differentiation into bone cells, which may have long-term implications for regenerative medicine for bone disease," Hung said.

Source: University of Texas