The 3rd annual NIGMS Director’s Early Career Investigator Lecture, titled “Ancient Bloodsuckers, Disposable Genes, and What It All Means,“ took place on Tuesday, Apr. 17 on the campus of the National Institutes of Health. An archive of the lecture can be found here: https://videocast.nih.gov/summary.asp?live=27347&bhcp=1
The first known descriptions of cancer come from ancient Egypt more than 3,500 years ago. Early physicians attributed the disease to several factors, including an imbalance in the body’s humoral fluids, trauma, and parasites. Only in the past 50 years or so have we figured out that mutations in critical genes are often the trigger. The sea lamprey, a slimy, snake-like blood sucker, is proving to be an ideal tool for understanding these mutations.
The sea lamprey, often called the jawless fish, is an ancient vertebrate whose ancestor diverged from the other vertebrate lineages (fish, reptiles, birds and mammals) more than 500 million years ago. Jeramiah Smith, associate professor of biology at the University of Kentucky, has discovered that lamprey have two separate genomes: a complete genome specific to their reproductive cells, consisting of 99 chromosomes (humans have 23 pairs) and another genome in which about 20 percent of genes have been deleted after development. By comparison, all human cells—even the reproductive cells—maintain a complete genome throughout our lifetimes.
Using the lamprey model, Smith and his colleagues have learned that many of these deleted genes—such as those that initiate growth pathways—are similar to human oncogenes (i.e., cancer-causing genes).
Humans (and most other organisms) have a different way of handling growth-related genes after they are no longer needed. Rather than deleting unwanted genes, we wrap them up in special proteins that essentially hide them away within our cells. Our evolutionary strategy, though, is not as foolproof as that of the lamprey. Sometimes the tucked-away genes accidentally get turned on, resulting in out-of-control cell growth that we know as cancer.
To learn more about Smith’s research on the lamprey, tune into the archive of his recent Early Career Investigator lecture. At the end of the lecture, Smith spoke with NIGMS director Jon Lorsch about careers in basic biomedical research. Smith also fielded questions about his research and career from undergraduate students who attended the lecture.
Dr. Smith’s research is funded in part by NIGMS grant 5R01GM104123.