Dataset Information

No difference in kinetics of tau or histone phosphorylation by CDK5/p25 versus CDK5/p35 in vitro.

ABSTRACT: CDK5/p35 is a cyclin-dependent kinase essential for normal neuron function. Proteolysis of the p35 subunit in vivo results in CDK5/p25 that causes neurotoxicity associated with a number of neurodegenerative diseases. Whereas the mechanism by which conversion of p35 to p25 leads to toxicity is unknown, there is common belief that CDK5/p25 is catalytically hyperactive compared to CDK5/p35. Here, we have compared the steady-state kinetic parameters of CDK5/p35 and CDK5/p25 towards both histone H1, the best known substrate for both enzymes, and the microtubule-associated protein, tau, a physiological substrate whose in vivo phosphorylation is relevant to Alzheimer's disease. We show that the kinetics of both enzymes are the same towards either substrate in vitro. Furthermore, both enzymes display virtually identical kinetics towards individual phosphorylation sites in tau monitored by NMR. We conclude that conversion of p35 to p25 does not alter the catalytic efficiency of the CDK5 catalytic subunit by using histone H1 or tau as substrates, and that neurotoxicity associated with CDK5/p25 is unlikely attributable to CDK5 hyperactivation, as measured in vitro.

SUBMITTER: Peterson DW

PROVIDER: S-EPMC2840295 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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No difference in kinetics of tau or histone phosphorylation by CDK5/p25 versus CDK5/p35 in vitro.

Peterson Dylan W DW Ando D Michael DM Taketa Daryl A DA Zhou Hongjun H Dahlquist Fredrick W FW Lew John J

Proceedings of the National Academy of Sciences of the United States of America 20100201 7

CDK5/p35 is a cyclin-dependent kinase essential for normal neuron function. Proteolysis of the p35 subunit in vivo results in CDK5/p25 that causes neurotoxicity associated with a number of neurodegenerative diseases. Whereas the mechanism by which conversion of p35 to p25 leads to toxicity is unknown, there is common belief that CDK5/p25 is catalytically hyperactive compared to CDK5/p35. Here, we have compared the steady-state kinetic parameters of CDK5/p35 and CDK5/p25 towards both histone H1, ...[more]

PMID: 20133653

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Project description:Abstract The survival advantage of glioma stem cells (GSCs) represents a critical mechanism for growth, therapy resistance and recurrence in glioblastoma. So far, targeting GSCs has not been highly specific, since these cells co-opt the normal developmental signaling pathways. We have demonstrated that the activated CDK5-CREB1 signaling axis regulates GSC self-renewal and also promotes radiation-resistance. Thus targeting CDK5 signaling is highly rational, yet there are challenges. Most of the available CDK5 inhibitors also target other CDKs non-specifically. In collaboration with The Center for Molecular Evolution and Drug Discovery, we are developing novel CDK5 inhibitors that are highly potent and specific. METHODOLOGY: The CKD5-p25 crystal structure (pdb code 1UNL) was used to conduct a virtual high throughput screen (vHTS). A library of 10 million commercially available compounds which had been filtered to ensure they possessed good drug-like properties was screened against the crystal structure. The top 33 compounds based on their predicted target binding, synthetic feasibility and availability were tested in an in vitro kinase assay to measure CDK5 inhibition. RESULTS: Of the 33 potential hit, 11 compounds showed a CDK5 inhibition of < 50 µM. These 11 hits represent 4 distinct chemical scaffolds. Two of them have IC50 < 1 µM, with one compound having an IC50 < 0.4 µM. The vHTS and subsequent in vitro testing have therefore confirmed the identification of several new series of potent CDK5 hit compounds. We are now characterizing the kinase selectivity of our different hit series and evaluating their activity in cell-based assays. This will help focus efforts on the most promising 1–2 scaffolds for further medicinal chemistry optimization to improve the compounds’ potency, selectivity and brain penetration. Ultimately, our optimized compounds will be tested in GBM models to demonstrate their effectiveness in inhibiting CDK5 as a new approach for treating GBM.

Dataset Information

No difference in kinetics of tau or histone phosphorylation by CDK5/p25 versus CDK5/p35 in vitro.

Publications

No difference in kinetics of tau or histone phosphorylation by CDK5/p25 versus CDK5/p35 in vitro.

Similar Datasets

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