BIONEER's unique Drug Target & Toxicity Identification Services: GPScreen™
An Innovative Technology for Drug Target Identification using Drug-induced Haploinsufficiency (DIH) in the World's First Fission Yeast S. pombe Genome-wide Heterozygous Deletion Mutant Library
The world's only innovative drug target identification technology based on S. pombe Genome-wide Deletion Mutant Library
Almost all types of drug targets possible to be screened at the genome level
Live cell-based screening
Fast and accurate high-throughput screening (HTS)
Applicable to drug repositioning, natural drug target discovery, drug toxicity evaluation
Drug target Identification and drug toxicity evaluation
Drug prioritization
Drug repositioning and drug efficacy improvement
Natural drug target discovery and mechanism of action (MOA) study
Chemogenomic profiling
Accurate drug target identification is the first and the most crucial step for not only increasing the success rate for the new drug development, but also understanding the mode-of-actions, improving efficacy, tracing and avoiding side-effects. Bioneer has developed a new a high-throughput genome-wide drug target screening system called GPScreen™ and made it commercially available for researchers to be used for their drug discovery needs. This technology covers a broad spectrum of drug candidates in whole disease areas from cancers & metabolic diseases to neglected & rare diseases. This will ultimately provide the total solutions for an efficient drug discovery through providing clear-cut answers to problems such as drug-target(s) and toxicity as well as mode-of-actions of drug candidates.
GPScreen™ is based on S. pombe genome-wide deletion mutant library, developed together with Bioneer and the Korea Research Institute of Bioscience & Biotechnology (KRIBB) in collaboration with Dr. Paul Nurse of Cancer Research Center UK (Nat. Biotech, 28, 617–623, 2010). However, Bioneer has all the business' exclusive rights to this library and provides it for genetic and chemical screening such as drug target identification, gene expression profiling and synthetic lethal profiling.
The genomic library consists of a total of 4,845 gene variants and covers about 98.5% of the entire genome of the fission yeast S. pombe. Individual variants are those in which one of the pair of individual genes in normal cells is deficient by homologous recombination (Refer to image).
'Drug-induced Haploinsufficiency (DIH)' refers to the increased sensitivity of a heterozygous deletion mutant (a variant in which a specific protein is expressed to about half of a normal level) to a specific drug. This phenomenon occurs when a drug acts on a mutant in which a particular gene is missing and therefore, is considered to be a valuable tool for drug target identification. Previously, a number of reports have provided identifications of drug targets using DIH in the budding yeast S. cerevisiae (Baetz K et al., 2004; Lum et al., 2004). However, the fission yeast S. pombe is considered be a more ideal cell division model of mammalian cells since its cell cycle pattern is closer to that of mammalian cells (including human cells) than that of S. cerevisiae.
GPScreen™ technology can accurately define the drug targets at the genome level.
Figure 1. Drug Target Identification using GPScreen™
When a actin-binding inhibitor cytochalasin A (Fig. 1A) was treated to the S. pombe heterozygous deletion mutant library, a act1 gene deleted mutant showed more potent growth inhibition by the agent compared to those of other mutants, demonstrating that a human actin homologue gene act1 could play a role as a target of cytochalasin A in the S. pombe genome (Fig. 1B)
▶ Using the drug action point discovered via GPScreen™ , target validation studies are possible on human cells.
IMethods for Validating Drug Targets in Human Cells
Bioneer has about 20,000 siRNA libraries for human genes.
By using the human orthologs of the identified target candidates from GPScreen™, gene knockdown can be analyzed to verify the gene in human cells using the siRNA library.
1) Analysis of human homologous gene expression regulation by drugs in human cells
Figure 1. Photos and the graphs showing the inhibition of POLG expression by Sunitinib in the Hela human cell lines
(A) To measure the cellular responses of Hela cells to sunitinib, the cells were spread onto m-slide 8-well plates and treated with 0 µM or 5 µM of sunitinib for 48 h. Then, the level of POLG proteins was observed with immunocytochemistry using an anti-POLG antibody and goat anti-rabbit IgG-TRITC antibody in fluorescent confocal microscope.
(B) Hela cells were treated with 0 µM or 5 µM of sunitinib for 48 h, and POLG mRNA levels in the treated cells were measured by qRT-PCR.
2) Analysis of inhibitory effect of human homologous gene expression using BIoneer's human siRNA library
Figure 2. Photos and the graphs showing the knockdown of POLG dramatically increased the cytotoxicity by sunitinib in a human cell line (Hela cells).
(Upper panel) After the treatment of siRNAs (5 nM, 48 h), the cells were further treated with sunitinib (5 µM) for 48 h, and the cell mass was measured by SRB assay.
(Bottom panel) The cells that have went through SRB assay were observed under a microscope.
IIApplication of GPScreen™ technology to derive new drug development candidates
In addition, GPScreen™ technology is also available for the screening of safer compounds between drug candidates in the early stages of new drug development for comparison. When this technology was used for analysis of target profiles at the genome level, toxic drugs showed a broader target spectrum than non-toxic drugs. It represents the toxicity profile of the drug in the human body and can be used effectively for drug prioritization for the safest drug among the same kind of candidate substances.
Figure 3. Targeted spectrum comparison after GPScreen™ each toxic and nontoxic drugs