Last January, I inaugurated this column with a look at three technology developments from 2005 that could soon be in kits. None are commercialized yet, but here are three more that should join them soon.
Let's start with a drug-inducible system for protein stabilization.
Key to Wandless' system is a mutant FKBP12 protein that is degraded as soon as it's made, unless it is bound to a small-molecule ligand called Shield-1. "This new technique essentially allows investigators to use small molecules to regulate the expression levels of any protein of interest," Wandless writes in an E-mail. "We target proteins directly (not precursor DNA or RNA), so the method is considerably faster than transcriptional switches or RNAi. It is also dose-dependent, which means that the system is tunable with expression levels varying as a function of ligand concentration."
Wandless says his team has fused 26 different proteins to the so-called destabilization domain, "and we're 26 for 26" in inducing their degradation. Now he's adapting the system for live animal work. "We hope it will work in vivo and are currently testing it," he says. Wandless says Stanford's office of technology licensing is in negotiations with several companies to commercialize his system, though he adds he'll give it to anyone who asks.
Didier Trono and Patrick Aebischer of the Swiss Institute of Technology, Lausanne, also developed a drug-inducible gene-expression system. Whereas Wandless' method relies on protein stability, Trono and Aebischer's is based on chromatin modification.
The system uses a lentiviral vector containing a series of tetracycline repressor-binding sites, a transgene, and a regulatory protein called TRKRAB, for fusion of the tetracycline repressor to a Kruppel-associated box domain. TRKRAB can recruit histone deacetylases and methylases to the DNA, converting it to heterochromatin over some two or three kilobases. The team built two variants, one that functions in the presence of tetracycline, and one that functions in its absence.
The system, Trono explains, can block transcription from polymerase II or III promoters, whether in cell culture, stem cells, or in vivo. It enables drug-controlled RNA interference. And, unlike standard tet-based regulatory systems, this one requires no promoter modification, "so it's far more flexible." Trono hasn't taken any steps to commercialize his technique. He has sent reagents to hundreds of colleagues; however, researchers can obtain them from Addgene (www.addgene.org), a Boston-based distribution firm, for $45 to $65 per plasmid.
Finally, from James Kadonaga, chair of molecular biology at the University of California, San Diego, comes a new promoter.
According to Kadonaga, SCP1 could prove useful anywhere amped-up protein expression is needed. The University of California has filed a patent application for the invention and now is looking to commercialize it. "There has been pretty good interest from some major companies," he says, but Kadonaga won't say which ones.