Monitoring Alternative Splicing
Although alternative splicing was discovered in the late 1970s, it has only recently been appreciated that almost 60% of all genes undergo some form of mRNA splicing, which is a potential source of diversity for protein expression.
Characterization of splice-specific alterations can provide potential new therapeutic targets and diagnostics. Exonhit Therapeutics (www.exonhit.com) recently launched its SpliceArray Service to detect and quantify these alternative-splicing events. This is now available using G-protein coupled receptor and ion-channel microarrays; future microarrays will include nuclear receptors and co-regulators, as well as the apoptosis-signaling pathway.
"We've developed a bioinformatic platform and database that utilizes the mRNA and EST (expressed sequence tag) public collection and aligned all those sequences back to the human genome. This is the database for all the source information for SpliceHit, our program that identifies the events," says Richard Einstein, Ph.D., vp, research, USA.
A set of six proprietary oligonucleotides is used to surround and monitor each event that has been identified. "We then take the probes we've designed against this event and submit them to Agilent Technologies (www.agilent.com), which builds an array for us," Dr. Einstein adds.
The service, launched in February 2005, is currently being used mostly for diagnostics and drug discovery, but can also be used for biomarker discovery, drug profiling, quality control, and pharmacogenomics.
"Alternative splicing is a sensitive and dynamic process that can be influenced by drug treatment and disease, and it is a strong mechanism for gene expression, signaling, and protein function. Our splice arrays give researchers the first real opportunity to use a tool that's been designed to identify all these different transcripts and events that are occurring," summarizes Dr. Einstein.
Eugene Brown, Ph.D., senior director, molecular profiling and biomarker discovery, biological technologies department, Wyeth Research (www.wyeth.com), will present how to combine tissue microarray analysis with transcriptional profiling for target identification. The researchers were able to identify a number of candidate targets suitable for the treatment of prostate cancer.