January 7, 2009

Protein discovered to repair DNA

A protein known for signaling cell injuries and preventing damaged cells from proliferating also repairs DNA, a published U.S. university study found.

Mre11 -- part of a complex of proteins involved in DNA damage repair in mammals -- recognizes the damage and rapidly relocates to where a strand of genetic material is broken and could possibly join to a different DNA molecule, the University of Michigan researchers said in the journal Cell.

Earlier research suggested Mre11 functioned only as a gatekeeper, signaling the cell injury and preventing damaged cells from proliferating.

But Dr. David Ferguson, assistant professor of pathology at the University of Michigan Medical School, and colleagues discovered Mre11 also serves as a caretaker, repairing DNA by acting as a nuclease, an enzyme that modifies and processes the broken DNA ends.

When the protein complex doesn't work properly, a person becomes significantly predisposed to cancer and immunodeficiency, where the immune system's ability to fight infectious disease is compromised or entirely absent, the researchers said.

They said their findings could have important implications for cancer treatment by helping oncologists to predict a tumor's sensitivity to radiation and other therapies, making it more vulnerable to treatment.