Gene Function Research

Lisa Stubbs and colleagues gain valuable information from ORNL's mouse collection. Photograph by Tom Cerniglio.

You have a unique identity, home address, and body structure. So does every human gene. The current emphasis of the Human Genome Program, co-sponsored by the Department of Energy, has been to determine the identity, location, and sequence of the chemical building blocks of each of the estimated 80,000 genes in the human genome. Now that more is known about where genes are and what they look like, ORNL is positioning itself for the next logical step of the program—finding out what genes do. When information on the entire human genome becomes accessible, experiments on gene function can be approached on a whole genome basis, not just one gene at a time—hence the term "functional genomics."

ORNL is positioning itself for the next logical step of the
program—finding out what genes do.

In a sense, the Human Genome Program is developing a "telephone book" that lists the name, address, and phone number of each of the human genes. For the science of functional genomics, biologists will use the "phone number" for each listed gene to "call up" groups of genes to ask questions about what they do—through gene function experiments. ORNL has the experts and model organisms to use this limited information to link the location and structure of genes to the actual function they control (e.g., breathing).

Functional genomics has become a goal of ORNL's efforts because our researchers both have proven proficiencies in analyzing the functions of genes and have developed technologies that can be used to facilitate these experiments. In the past, we first learned about mouse genes by exposing mice to radiation and observing body changes (e.g., altered fur color) that could be related to altered genes. Similar mutations were produced in mice at ORNL, using chemical agents. Today, we produce mouse mutants through both chemical mutagenesis and a form of genetic engineering called targeted mutagenesis. In this technique, we "make" new mice by inserting an engineered gene into a mouse in the embryonic stage, ultimately causing a disruption of the corresponding gene in the host animal. If the disruption causes an abnormality, impaired function, or a disease in the mouse, then it is possible to determine which gene is partly responsible for the defective trait or function (e.g., a poorly working kidney). At ORNL "mouse models" for polycystic kidney disease, Type II diabetes, sickle cell anemia, cleft palate, genetic-based obesity, immunological defects, neurological disorders, and many other conditions have been developed. The information they provide about altered gene function could lead to a cure for at least one human genetic disease.

A new ORNL initiative in functional genomics, which will be supported by internal funding for the next four years, will enhance the Laboratory's capabilities in support of the DOE mission. With a focus on mouse mutagenesis, the functional genomics initiative will build on our expertise in mouse mutagenesis and our extensive mouse mutant resource being maintained in the Biology Division—our unique colony of more than 120,000 mice. In a broader sense, it will combine ORNL's expertise in mammalian genetics with our competencies in structural biology, computational sciences, robotics, automation, and instrumentation development. Integration of the expertise of molecular biologists with computer scientists and mathematicians is particularly important because analysis of the sequences of whole genomes has been hastened by creation of new algorithms and other mathematical feats. Our biologists' collaborations with computer scientists, analytical chemists, and engineers is providing highly productive experimental capabilities and technological breakthroughs for genetics research.

ORNL also has strong capabilities in analyzing structure and function of proteins, or gene products. Mutations of genes in living organisms give rise to mutated proteins that must be isolated and characterized to understand their consequences in the body. Mutated proteins encoded by relevant genes can also be generated in the laboratory by both chemical and genetic means. Protein engineering through recombinant DNA technology enables rational redesign of protein structure. This powerful approach will enhance our ability to understand protein function and tailor the properties of proteins in animals and plants for use in medicine, industry, agriculture, and biotechnology.

Our research in functional genomics will help us continue our tradition of successes in the biological sciences, thereby serving the needs of DOE and our society, and it will facilitate expanded outreach and partnerships under industry and academia. These multidisciplinary achievements, which bridge basic and applied research, have been honored by two Enrico Fermi Awards from DOE and more than a dozen memberships in the National Academy of Sciences.

Brad Yoder examines mouse embryos that turn blue, indicating the expression of the disrupted gene that causes polycystic kidney disease. Photograph by Tom Cerniglio.

Thanks to our mice and other research tools, we have discovered that health effects of radiation exposure are related to the intensity of the doses and that radiation is especially harmful to embryos in the early stages of development, prompting rules limiting the use of X rays on pregnant women. We found that the presence of a Y chromosome specifies male gender and that only one of two X chromosomes in a cell is active. We performed the world's first experimental bone-marrow transplants in mice. We performed the world's first successful freezing, thawing, and implantation of mouse embryos, which were brought to term in surrogate mother mice, establishing the basis for modern animal breeding and human fertility treatment.

Apart from mouse genetics, we have enjoyed other stunning successes: the first analytical separation of the building blocks of DNA and RNA, codiscovery of the nucleosome (the basic structural component of chromosomes) and low-level resolution of its structure by X-ray crystallography, codiscovery of messenger RNA (which conveys genetic information to the protein-synthesizing apparatus in all cells), discovery of biochemical pathways for repairing damaged DNA (thereby preventing mutations and cancers), rational design of enzyme inhibitors (a cornerstone of drug discovery), and development of the zonal centrifuge (for production-scale preparation of vaccines).

As an extension of these studies, we are attempting to unravel the role of RNA in the regulation of cell growth and differentiation. We are exploring the use of antibodies to deliver chemotherapeutic agents to certain organs or cell types. We are also using sophisticated techniques of genetic engineering to systematically redesign proteins found in nature in the hope of improving biomass yields (for food and energy) and developing effective drugs for treating cancer.

Fortunately, DOE's Office of Health and Environmental Research is an advocate and sponsor of our research. This support should help us not only play an important role in the second stage of the Human Genome Program but also contribute to the multifaceted missions of DOE in the life sciences.

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