Telomere Meeting Draws Experts from Across Disciplines
Photo: Steve McCaw
Can telomeres serve as valuable markers of exposure to pollutants or stress, or of vulnerability to disease? An interdisciplinary group of experts gathered at NIEHS recently to discuss these and other questions about telomeres, which are caps on the ends of chromosomes that shorten each time a cell divides. Telomeres decrease in length as people age.
The workshop, “Telomeres as Sentinels for Environmental Exposures, Psychosocial Stress and Disease Susceptibility,” was organized by Dr. Michelle Heacock of NIEHS’s Hazardous Substance Research Branch and Dr. Lisbeth Nielsen of NIA’s Division of Behavioral and Social Research.
“We are here to generate a strong vision for the rapidly developing field of telomere research,” said NIEHS and National Toxicology Program director Dr. Linda Birnbaum, in opening remarks. “There are many questions in the field and we need to advance collaboratively—basic scientists together with clinicians and epidemiologists.”
Basic scientists are uncovering the details of telomere biology in the laboratory, while clinicians and epidemiologists explore telomere length as a marker of human health. Studies suggest that excessively shortened telomeres may be associated with an increased risk of cardiovascular disease and some degenerative diseases. Extra-long telomeres may be associated with an increased risk of certain cancers. However, these conclusions are far from settled.
Participants quickly zeroed in on the question of precise and reliable measurements of telomere length. Some scientists are concerned that differences among study results may represent variations in measurement. Common measurement techniques include quantitative polymerase chain reaction (qPCR) and a combination of flow cytometry and fluorescent in situ hybridization (Flow-FISH). Although some scientists criticized the potential for error in measurement of telomere length using qPCR, others said it was not credible that measurement error alone would produce the effects on telomere length observed using the method. Dr. Stacy Drury of Tulane University suggested the need to balance use of qPCR and Flow-FISH and to closely monitor the reproducibility of measurements.
Photo: Steve McCaw
One point of consensus was that telomere length during childhood is one of the most important determinants of telomere length in adults. This means that some data on telomere length in adults will reflect patterns set in early life, unless researchers have the information to control for childhood length, suggested Dr. Elissa Epel of the University of California, San Francisco.
Dr. Pathik Wadhwa of the University of California, Irvine, said a person’s telomere length may initially be set in the womb. “There is preliminary evidence that maternal stress and nutrition-related factors during pregnancy may influence telomere length,” he said. Other scientists suggested that childhood exposure to stress or environmental factors such as ionizing radiation may have a greater effect on telomere length than similar exposures during adulthood, underscoring the need to understand the biology of telomere length at different life stages.
Other evidence suggests telomere length may be partly inherited. Dr. Abraham Aviv of Rutgers University emphasized that unless scientists account for heritability, it can be hard to analyze the influence of environmental factors on telomere length.
The question of whether telomere length can serve as a marker of exposure to environmental pollutants and stress remains unsettled. Some scientists proposed that telomeres may indicate vulnerability to environmentally induced disease. Others, who supported the potential for telomere length to be a marker, acknowledged that challenges with measurement need to be resolved.
Dr. Colter Mitchell of the University of Michigan reflected that developing a new biomarker always involves a lengthy scientific process. He suggested that it starts with initial excitement about the method, which becomes disillusionment as challenges are realized and then solid methods emerge.