By Marla Vacek Broadfoot
Approximately 20,000 genes make up the instruction manual for our bodies. To figure out what each of these genes does, scientists have generally used two tactics: either “knocking down” the gene or the opposite, overexpressing it. The former is a process of elimination – by knocking down a gene, the researchers can see what parts of the cell don’t function normally. Conversely, by overexpressing the gene or ramping up its activity, researchers can determine what happens when the gene overdoes its job.
Though the approach might sound straightforward, it can actually take many rounds of trial and error to perfect, for each gene and each cell type. Over the past decade, researchers have begun to hijack naturally occurring viruses like lentivirus to manipulate genes in hard to reach cells, but even that method can be challenging for labs not already set up to perform the technique. Luckily, researchers at UNC have the Lenti-shRNA Core Facility to turn to for help. The core relies upon the expertise of Tal Kafri, MD, PhD, associate professor of microbiology and immunology with over fifteen years of experience working with lentiviral vectors.
“Lentiviral vectors are a tool that enables you to ask relevant and interesting biological questions,” said Kafri, director of the core facility. “To use this tool, you shouldn’t have to waste time acquiring new technology that is not directly related to your work. You shouldn’t have to become an expert in vectorology or gene delivery, you should just be able to focus on your research. That is the point of our core facility, to help the research move forward and to enhance the ability of the researcher to answer questions without having to worry about the technical aspects of knocking down or overexpressing the genes they are most interested in.”
The core is one of over 60 such facilities at UNC offering a wide range of services to the research community, including cutting edge technologies, high end instrumentation, technical support, and education. Researchers using the Lenti-shRNA Core Facility have access to two lentiviral vector libraries: one containing small hairpin RNAs for silencing genes, and another, more recent addition, containing more than 10,000 cDNAs for overexpressing genes.
“The two libraries complement each other,” said Kafri. “With these libraries, researchers can knock-down and overexpress most of the genes in the human genome. Because both libraries are in the context of the lentivirus, the researchers can do their experiments in almost every human or mouse cell line and in vivo. I believe it has given a huge advantage to the investigator over other universities.”
In addition to these libraries, the core has recently developed a new methodology that enables investigators to turn on the lentiviral shRNAs used in their experiments with the simple addition of the antibiotic tetracycline. Using this new system, researchers can now grow cell populations containing toxic yet silent lenti-shRNAs and activate their expression when they are ready to study a gene of interest.
Averaging about 10 to 20 requests a month, the core facility still has the capacity to take on more projects. One investigator who has taken advantage of this resource is Mark Zylka, PhD, an associate professor in cell biology and physiology who studies molecular mechanisms of pain.
“Tal Kafri’s core facility was essential in allowing us to rapidly obtain lentiviruses for knockdown experiments with neurons,” said Zylka. “Reagents from this core directly contributed to a high visibility research project in our lab.” Kafri jokes that when his core is successful, it means he won’t see a client again for quite some time. Investigators use the core’s resources to jump-start their research on a gene of interest, which they can then delve into more deeply. “When the system works, it is the beginning of the project. They could then spend the next three years with two postdocs characterizing the system in vitro and in vivo further understanding the underlying biochemistry and signaling,” said Kafri. “It is not a bad problem to have, because it means we have more time to help other scientists get their research going.” To learn more about the Lenti-shRNA Core Facility or to obtain its services, please visit http://www.med.unc.edu/lenti-shrna or send an email to email@example.com.