Nobel Winners' Findings Opened New Area of Illness Study

Major discoveries about telomeres—those DNA-protein complexes that cap the end of chromosomes—have garnered three scientists the 2009 Nobel Prize in Physiology or Medicine.

The announcement was made by the Nobel Assembly at the Karolinska Institute in Stockholm on October 5. The scientists are Elizabeth Blackburn, Ph.D., a professor of biology and physiology at the University of California, San Francisco; Carol Greider, Ph.D., a professor of molecular biology and genetics at Johns Hopkins University; and Jack Szostak, Ph.D., a professor of genetics at Massachusetts General Hospital.

As early as the 1930s, telomeres had already been observed by scientists, though nothing was known about their function. In 1982, however, Blackburn and Szostak reported that telomeres taken from one organism—a unicellular organism called Tetrahymena—could protect chromosomes in an entirely different organism—yeast—from degradation. Thus, it looked as if this might be telomeres' raison d'etre—to protect chromosomes from degradation.

Then on Christmas Day 1984, Blackburn and Greider identified an enzyme that makes telomeres. They named it telomerase.

In brief, the scientists had discovered a function for telomeres as well as an enzyme that makes them—discoveries that would ultimately bring them a Nobel Prize.

Moreover, their findings launched a new subfield of study—the exploration of telomeres in aging and cancer. Here, too, there have been some intriguing discoveries.

For example, the older a person is, the fewer times his or her cells divide when cultured in the lab, and the reason is because the telomeres shorten a bit during each cell division. Finally the telomeres become so short that the cell cannot divide any more and dies.

Conversely, if telomerase activity is high, telomere length is maintained, and cellular senescence is delayed. Cancer cells often have increased telomerase activity. Thus some scientists proposed that cancer might be treated by eradicating telomeres. Several studies are now under way in this area, including clinical trials evaluating vaccines directed against cells with elevated telomerase activity.

Telomere research has also segued into the field of mental health and illness.

For instance, in 2004 Elissa Epel, Ph.D., an assistant professor of psychiatry at the University of California, San Francisco, and colleagues reported that chronically psychologically stressed subjects had significantly shorter telomeres than did subjects who were not chronically stressed. This finding suggested that psychological stress might hasten the telomere-shortening process that occurs with normal aging (Psychiatric News, January 7, 2005).

In 2006 Naomi Simon, M.D., associate director of Massachusetts General Hospital's Center for Anxiety and Traumatic Stress Disorders, and colleagues reported telomere shortening in subjects with major depression or bipolar disorder. “Our study is the first to demonstrate accelerated telomere shortening in mood disorders, or in any chronic psychiatric disorder,” they noted, “and suggests that chronic mood disorders contribute to acceleration of aging processes” (Psychiatric News, June 2, 2006).

And recently, Audrey Tyrka, M.D., Ph.D., an assistant professor of psychiatry at Brown University, and colleagues found that subjects who had been emotionally, physically, or sexually abused as children had significantly shorter telomeres than did subjects who had not been so abused. Moreover, these results held even when age, gender, level of education, smoking status, and body mass index were considered. The results were reported online October 15 in Biological Psychiatry.

That Blackburn, Greider, and Szostak have received this year's Nobel Prize in medicine “is extremely well deserved,” Epel told Psychiatric News. “Their scientific discoveries … have sprouted new fields in many disease areas. More significantly, the cell-aging system is important across diseases, and we think especially important to brain aging and psychiatric disease.”