University of Kentucky College of Medicine researchers are refining novel technologies to study the genes that are active, or expressed, in the central nervous system (CNS).
This work is being supported by two $800,000 grants from the National Institutes of Health (NIH).
Identifying genes that are at work in the brain will lead to a much greater understanding of neurological and mental diseases and disorders. Many diseases of the nervous system (including mental illnesses, dementias and addictive disorders) are known, or thought, to result from genetic factors. Research findings from these projects will be crucial to understanding, detecting, preventing and treating diseases such as Alzheimer's, depression or schizophrenia.
Currently, it is a painstaking process to determine which genes are active and what the functions of those genes are, particularly in the nervous system. These research projects aim to speed up this process.
The UK College of Medicine research projects are detecting either proteins or messenger RNA, the products of active genes, to determine the identity and function of the active genes in neurons, or map the genes to specific nerve cells. Technical advances made by the research teams will accelerate the mapping process by detecting products of multiple genes at the same time.
Department of Pharmacology
One of the UK College of Medicine research teams is led by Philip Landfield, Ph.D., professor and chair, and includes Kuey-Chu Chen, Ph.D., assistant professor, Olivier Thibault, Ph.D., assistant professor, and Eric Blalock, Ph.D., senior research associate, all of the Department of Pharmacology, UK College of Medicine, and James Herman, Ph.D., associate professor, Department of Anatomy and Neurobiology, UK College of Medicine.
For the past five years, Landfield's team has been working with rodent brain sections prepared using a novel method. The researchers take a very thin section, containing a nerve cell layer, and then induce a crack along the cell layer. Like a zipper, the key characteristic of this preparation is that the section gradually separates, or unzips, along the layer of cells. "To our knowledge, we are the only research group in the country currently using the zipper slice to collect an intact single neuron for analysis of the genes expressed in the cell," Landfield said.
Because of the way the section unzips, the researchers can remove a single intact neuron from the sample and use it to study gene activity. This is important for two reasons. First, the nervous system is composed of hundreds of different kinds of cells, each kind performing a different function. By analyzing an intact neuron, the researchers are able to determine the identity and characterize the functions of the cell from which they are identifying the active genes. Second, with an intact neuron the researchers are able to quantify the activity of the gene by determining the amount of protein or RNA present in the entire cell. This more accurate information about gene activity eventually will help in understanding why human brain cells, which share many properties with rodent brain cells, are resistant or vulnerable to disease.
Department of Physiology
The second UK research team is led by Timothy McClintock, Ph.D., associate professor, and Douglas McMahon, Ph.D., associate professor, both of the Department of Physiology, UK College of Medicine.
The goal of this research project is to identify genes and neurons that are involved in daily, or circadian, rhythms. Increasing our understanding of the biological clock mechanism ultimately may lead to treatments for jet lag, seasonal affective disorder (SAD) and certain sleep disorders.
McMahon's part of the team is introducing a foreign gene into the DNA of mice. The foreign gene produces a fluorescent protein only in neurons that have a circadian rhythm. This allows the researchers actually to see which neurons follow a circadian pattern and then analyze the genes that are at work in those neurons.
"It's like the memory game that children play with cards where you turn all the cards upside down and try to find matching pairs," McClintock said. "We're trying to find the matching neurons that are all involved in circadian rhythms. But we're playing with a marked deck. When our cards are turned upside down now, the matching neurons, or the ones that share the function of being involved in circadian rhythms, are glowing bright green."
McClintock's part of the research team is developing ways to identify large numbers of active genes simultaneously in the glowing neurons.
"Putting together the work of the two parts of our team creates a method that is like a Web browser for genes," McClintock said. "It allows us to sort rapidly the relevant sites, or genes, from the irrelevant ones."
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