Hong Kong researchers discover molecule that stimulates growth of stem cells

Hong Kong scientists are one step closer to understanding how the regenerative power of stem cells is activated, after discovering a molecule that facilitates the proliferation of muscle stem cells, known to build new muscle tissues when damaged.

The research was carried out by Professor Wu Zhenguo and his colleagues at the division of life science at the University of Science and Technology. They've been trying to unravel the mystery of the working mechanisms of Pax7, a protein that is present in the nucleus of skeletal muscle stem cells.

Their findings were published in the latest issue of , a leading bioscience journal. "We know if we can successfully unravel the function of Pax7, it will be very useful in understanding how muscle stem cells work," Wu said.

Pax7 was first discovered in 1993 but its importance in muscle stem cells was not revealed until 2000, when a group of Canadian scientists found that newborn mice which had Pax7 removed would be largely devoid of muscle stem cells and die within two weeks, showing that the protein is essential for muscle stem cells in young mice. But it had been unclear how exactly Pax7 worked.

Professor Wu's team identified a new molecule that helps explain the mechanism by which Pax7 functions. The protein, which they named Pax3/7BP, works like a bridge, connecting Pax7 with a particular complex of histone-modifying enzymes.

After the molecules are connected thanks to the protein, multiple Pax7 target genes are activated, resulting in the proliferation of muscle stem cells and the growth of muscle tissues in young mice.