Modified Cells for Enhanced R&D

Biowire Spring 2011 — Cell Lines — Models of Disease

The use of human cell lines in research has been fundamental to our understanding of human biology, drug discovery, and the manufacture of vaccines. However, our ability to manipulate the genome of these cells to create better models of disease or to increase bioproduction efficiencies had been limited. Now, with the advent of zinc finger nuclease (ZFN) technology, we can manipulate the genome of virtually any cell line to create new models of human disease and better tools for understanding basic biological processes. The research community is very excited about these revolutionary models, as evidenced by our silver medal position in The Scientist magazine’s Top Ten Innovations for 2010.

ZFNs are a class of engineered proteins that present us with a unique way of modifying the human genome. These proteins can be designed to create a highly targeted double strand break (DSB) anywhere within the genome. This DSB is then repaired via endogenous mechanisms. Repair via non-homologous endjoining results in a gene knockout, whereas repair via homologous recombination leads to precise gene insertion, deletion, or modification, i.e., a gene knock-in.

Historically, the human genome has been difficult to manipulate. Gene editing in human cells was restricted to the use of tedious methods of homologous recombination that required antibiotic selection and only worked in a few cell types. Functional genomics in human cells was largely limited to the use of overexpression and RNAi. ZFN technology has removed these barriers and allowed us to knockout or knock-in any gene in almost any human cell line. Furthermore, we have been able to precisely modify multiple loci in a single cell line. The flexibility and precision of this technology has allowed us to conduct elegant functional genetic manipulations in human cell systems. We believe these new cell lines, with highly specific genome modifications, will prove to be very useful to the research community.

Ease of genome manipulation in yeast led to the creation of a yeast library expressing GFP-tagged proteins from their endogenous loci. This enabled a high-content study of the yeast proteome, leading to a wealth of data on transcriptional regulation, as well as genetic and protein-protein interaction. The creation of a similar library was not possible in human cells. At Sigma Life Science, we seek to tear down this barrier. We have embarked on an ambitious journey to create a panel of human cell lines where we have tagged relevant genes in important biological networks and pathways to create a method to systemically and comprehensively assay pathway perturbations. By maintaining the integrity of the endogenous promoter, upstream and downstream regulatory elements, and untranslated regions, we believe that these reporter cell lines will be more physiologically relevant than other available cell lines and facilitate the study of transcriptional, epigenetic, and non-coding RNA gene regulation. The first step towards this process is the creation of a panel of cell lines where we have tagged important cytoskeleton genes with fluorescent protein tags at their endogenous locus. These cells will enable us to study transcriptional regulation and protein localization of the tagged proteins in a live cellular system. We also developed a novel Biosensor cell line that can be used in a high-throughput cellbased screening platform for the identification of novel EGFR activators and inhibitors.

Drug discovery efforts currently are focusing on developing new targets and repurposing existing drugs for new diseases. In addition, there are new initiatives taking place in drug discovery towards the development of personalized medicine. Personalized medicine is the tailoring of a drug regimen to each patient based on their genetic profile to maximize its benefits and minimize its harmful effects. With ZFN-modified human cell lines, it is now possible to mimic various “patient-relevant” genetic profiles. Using these cell lines, one can now identify lead compounds that will be selectively active in specific patient populations based on their genetic profiles. This will lead to the design of shorter, more successful clinical trials, resulting in lower costs associated with each drug that makes it to the market. Furthermore, these modified cell lines will provide great models to conduct target validation, lead compound optimization, and identify and treat drug resistance.

With innovative technologies at our disposal, and by collaborating with the research community, we are constantly striving to develop groundbreaking new cell lines and cell-based assays to enable new avenues of research. Human cell lines will continue to be a critical part of our scientific endeavor in all aspects of research and development. With our ability to specifically modify the genome of virtually any cell line, we will be creating new models that will enable you to investigate questions that were, until today, technically impossible.


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