María Blasco: Keeping a cap on cancer and aging

T elomeres, found at eukaryotic chromosome ends, are made up of tandem DNA repeats. In most cells, the number of telomeric repeats is reduced with each cell division. If telom-eres are ever completely lost, the exposed chromosome ends are recognized as damaged DNA, activating a DNA damage response that can eventually lead to senescence or apoptosis. The rare cell that escapes these fates risks developing chromosomal aberrations or genomic instability and becoming cancerous (1). The contribution that telomeres and telomerase—the enzyme that maintains telomere length in cells—make to preventing cancer (2) and aging (3–5) is the research passion of Dr. María Blasco at the Spanish National Cancer Research Center (CNIO) in Madrid. She entered the telomerase fi eld just as it was taking off, as a postdoc in Carol Greider's laboratory at the Cold Spring Harbor Laboratory in New York (1). Her career took off as well, and her work has been at the leading edge of the fi eld ever since. We caught up with her at her offi ce to learn more about her work on the cell's internal countdown clock. What attracted you to studying telomere biology? I think I always had a love for science generally, even as a child. I had a chemistry set growing up, and I loved to play with it. When I was in University, the topics that interested me most were cancer and aging. But I didn't get to work on these subjects right away because when I was looking for a laboratory for my PhD I felt the best laboratory at my institution was Margarita Salas' laboratory. She worked on the bac-teriophage DNA polymerase Phi29 and on the end-replication problem, which concerns how you copy DNA at the very end of a linear strand. While I wasn't initially interested in that topic, I knew I would learn a lot of useful techniques in her laboratory, like molecular biology. And I was right—those skills were very helpful when I got to Carol Greider's laboratory for my postdoc. Carol was just starting a junior group at Cold Spring Harbor, and I was happy to have the opportunity to work with her because a link between telomeres, cancer , and aging was hypothesized, but it had not yet been proven. The genes that make up the mammalian telomerase had not yet been identifi ed, so there was a lot of room for discovery …