Traditional gene inactivation technologies completely eliminate the expression of a targeted protein kinase in all or some tissues. Since protein kinases may also have non-kinase functions, the resultant phenotype may be due to the lack of kinase or non-kinase function(s) of a targeted kinase. Furthermore, it is possible that constitutive gene inactivation (utilizing traditional knock-out or knock-in techniques) may result in embryonic lethality. In contrast to gene inactivation and traditional knock-in techniques, KinaseSwitch technology only inhibits the enzymatic activity of a targeted kinase in the presence of our proprietary inhibitors (1Na-PP1, 1NM-PP1 and 3 MB-PP1). Other non-kinase functions are preserved.
Conventional gene-targeting technologies do not enable an investigator to quickly inhibit kinase activity at a precise time similarly to a pharmacological agent. With KinaseSwitch, however, rapid kinase inhibition at a precise time can be achieved simply by administering Taconic's proprietary inhibitor(s). To inhibit a targeted kinase at a specific embryonic or fetal stage of developmental, the inhibitor is administered to a pregnant KinaseSwitch female. The inhibitor readily passes through the placenta to act on embryos or fetuses at any chosen stage of development. Our inhibitors have also been shown to easily pass though the blood-brain barrier.
Current gene targeting techniques either permanently inactivate kinase gene expression or kinase function. These technologies do not mimic the effects of an antagonistic pharmacological agent (inducible and reversible drug inhibition). With KinaseSwitch, kinase inhibition is inducible and completely reversible. This is easily achieved by simply withholding administration of our proprietary kinase inhibitor agent.
A study by Jaeschke et al, (2006) demonstrated that simple gene ablation studies are not always sufficient for understanding protein kinase function. Previous gene ablation studies of the kinases cJun NH2-terminal kinases 1 and 2 (JNK1 and JNK2, respectively) demonstrated that JNK1 was a positive regulator and JNK2 was a negative regulator of cJun gene expression (Ronai, 2004; Sabapathy et al, 2004). However, KinaseSwitch technology demonstrated that kinase inhibition of JNK2 (J2MG/MG), in contrast to JNK2 gene ablation (JNK2-/-), reduced cJun mRNA (A) and cJun protein expression (B) when JNK1 was deleted (J1-/-). The researches concluded that JNK2, like JNK1, was a positive regulator of cJun gene expression. It was hypothesized that deletion of JNK2, in previous studies, induced increased function/ of JNK1.
A significant feature of KinaseSwitch technology is the high specificity of our proprietary ASKA inhibitors for a kinase's mutated ATP binding pocket. The inhibitor 1NM-PP1; 4-amino-1-tert-butyl-3-(1'-naphyl) pyrazolo [3,4.d] pyrimidine, a derivative of PP1, has been demonstrated to be highly specific for the mutated ATP binding pocket of multiple protein kinases. Bishop et al., (2000) demonstrated that 50% inhibitory concentrations (IC50s) of 1NM-PP1 was 6500 times lower for the mutated ATP binding pocket of Src vs. wild-type Src. 1NM-PP1 also demonstrated high-specificity for a variety of other mutated kinase substrates such as c-Fyn, c-Abl, CDK2 and CAMK II. Like 1NM-PP1, the PP1 derivative 1NaPP1 demonstrated high levels of specificity for mutated ATP binding pockets of the above kinases (see below).
Due to the extremely high affinity of Taconic's inhibitors for a kinase's mutated ATP binding pocket in KinaseSwitch mice, these models provide baseline pharmacological inhibition of only a single kinase, allowing direct comparison with candidate kinase inhibitors. Thus, important on- and off-target effects of a drug development candidate can be identified.
Bishop AC, Ubersax JA, Petsch D, Matheos DP, Gray NS, Blethrow J, Shimizu E, Tsien JZ, Schultz P, Rose MD, Wood JL, Morgan DO, Shokat KM. A chemical switch for inhibitor-sensitive alleles of any protein kinase. Nature, 2000;407:395-401.
Jaeschke A, Karasarides M, Ventura, JJ, Ehrhardt A, Zhang C, Flavel RA, Shokat KM, Davis RJ. JNK2 is a positive regulator of the cJun transcription factor. Mol Cell, 2006;23:899-911.
Sapapathy K, Hochedlinger K, Nam SY, Bauer A, Karin M, Wagner EF. Distinct roles for JNK1 and JNK2 in regulating JNK activity and c-jun dependent cell proliferation. Mol Cell, 2004;15:713-725.
Ronai Z. JNKing Revealed. Mol Cell, 2004;15:843-844.
View the next section - V. View the summary of KinaseSwitch features and benefits
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