Tracking families
The genome can be considered an archive of humankind's genetic history. Genes shared with primitive creatures inhabit the same coils of DNA as those that are uniquely human. But as a model of organization, the genome falls short.
Related genes — which have similar structures and, presumably, similar functions within cells — are as likely to reside on different sections of different chromosomes as to sit near one another. Neighboring genes may have entered the genome around the same time period, but their functions may diverge.
Fortunately, making sense of the genome's idiosyncratic order is much easier for scientists now that the entire map — every component of every gene on every chromosome — is on the Internet. Two organizations, the National Center for Biotechnology Information (NCBI) and the University of California at Santa Cruz, maintain websites where researchers can enter a gene's name or sequence and instantly get information on its location, function, structural similarities to other genes, published studies on it, and whether it occurs in other animals.
Gordon Freeman, PhD, is using the genome map to find connections between genes.
Such computing power has transformed the work of investigators like Dana-Farber's Gordon Freeman, PhD, a specialist in genes involved in the immune system's response to disease.
"In the old days [pre-early 1990s], genes were isolated one by one, and it took an enormous amount of work to find their 'cousins,' or related genes," Freeman says. "Now, we can make connections between genes and groups of them much more readily."
A study published last year by Freeman and colleagues at Brigham and Women's Hospital and Stanford University provides an example. The researchers hoped to find a way of distinguishing between two types of immune system cells, called Thelper1 and Thelper2. They discovered a gene responsible for a surface molecule on Thelper1 but not on Thelper2. While researching the gene on the NCBI website, Freeman found it was closely related to another known gene, TIM1, which had been discovered in kidney cells, and to the previously uncharted TIM2. His group named its newfound gene TIM3.
"In the space of two weeks, we had identified a previously unknown gene family and isolated all its members — three genes in humans and eight in mice," Freeman remarks. "We know from our research that TIM3 has a role in Thelper1, the most valuable cell for activating the immune response against cancer. Because related genes tend to have similar functions, we explored whether the other TIM genes are involved in the immune response as well. It turns out that they are."
This kind of discovery-by-association is made light-years faster by the genome map. "It has opened up huge possibilities for making connections," Freeman remarks. "We can look in many different directions at once."
- Next: Key players, bit actors
- Page: 1 | 2 | 3 | 4
