Finding May Explain Tumor Development
For the first time, scientists have shown conclusively how the protein that is missing or altered in the fatal childhood disease ataxia telangiectasia* (A-T) acts as a key regulator of cell division after DNA damage. The finding helps researchers understand how cells in A-T patients form tumors and may lead to new understanding of other neurological and immune disorders.
The new research shows that the protein, called ATM for A-T, mutated, is a type of enzyme called a protein kinase that reacts to DNA damage by chemically modifying and triggering accumulation of a molecular "brake," or tumor suppressor, called p53. This tumor suppressor is defective in about half of all human cancers and is the master control switch for a process that normally prevents cells from dividing. In A-T patients, the ATM protein is missing or defective. This delays the accumulation of p53, allowing cells to replicate without repair of their DNA and thereby increasing the risk of cancer. The new finding is separately reported by two groups of researchers in the September 11, 1998, issue of Science.1,2 Both studies were partially funded by the National Institutes of Health (NIH).
The ATM gene was isolated in 1995 in the laboratory of Yosef Shiloh, Ph.D., of Tel Aviv University in Israel, with collaboration from an international team of colleagues. Until now, however, researchers have been uncertain about precisely how the protein produced by this gene works.
"This is an important milestone in our attempts to understand ATM's
functions. It is also a step forward in our move from molecular genetics to the
cellular biology of A-T," says Dr. Shiloh, senior author of one of the new
reports. Similar findings are reported by Michael B. Kastan, M.D., Ph.D., of
St. Jude Children's Research Hospital in Memphis, and his colleagues. Now t
Contact: Natalie Larsen
NIH/National Institute of Neurological Disorders and Stroke