Researcher Lynn Megeney suggests DNA damage isn't necessarily bad: 'It's actually required for normal biological processes.' (CBC)

Stem cells that can repair and regenerate tissues may need to get their DNA chopped up as a normal part of growing up and turning into specialized cells like muscle cells, Ottawa researchers have found.

The finding is "going to completely change mindset in the way we look at DNA damage," said Lynn Megeny, co-author of a study published Monday in the Proceedings of the National Academy of Sciences. "DNA damage isn't necessary a bad thing. It's actually required for normal biological processes."

Until now, damage to DNA — the long strands of genetic material containing instructions that cells need to make proteins — has been thought of as something that kills cells or can turn them into cancer cells, said Megeny, a senior research scientist at the Ottawa Hospital Research Institute and associate professor at the University of Ottawa.

But Megeny's research team found that DNA strands must be broken in specific places in order for stem cells, which have the ability to divide themselves into a variety of specialized cell types, to mature into muscle cells.

"It looks like we need to have a regulated form of DNA damage — you actually have to go in and bust up all the DNA inside the cell."

Aims to control stem cells

In the process, some genes are turned off and others are turned on. Afterward, the DNA is repaired. Megeny's team is now trying to map the locations where the DNA is cut.

"Once you understand the sites of DNA damage, then you could probably take a stem cell, induce breaks in particular areas, and turn it into a cell type that you want it to become," he said.

He added that the finding is also important because the proteins that cut the DNA are involved in a controlled form of cell death. Because of that, some researchers have proposed blocking their activity.

Megeny said that if the same proteins are needed to make stem cells mature, blocking them could be counterproductive.

"While trying to cure one problem, you may actually instigate another problem."

The researchers made their findings while looking at a protein called caspase 3 that promotes cell death. In 2002, they found that when they blocked the protein, stem cells stopped producing new muscle fibres.

The more recent study has helped explain why: it appears caspase 3 activates a protein required to cut the DNA and induce the maturation of a stem cell into a muscle cell.