ABSTRACT
Polo-like kinase-2 (Plk-2) has been implicated as the dominant kinase involved in the phosphorylation of α-synuclein in Lewy bodies, which are one of the hallmarks of Parkinson's disease neuropathology. Potent, selective, brain-penetrant inhibitors of Plk-2 were obtained from a structure-guided drug discovery approach driven by the first reported Plk-2-inhibitor complexes. The best of these compounds showed excellent isoform and kinome-wide selectivity, with physicochemical properties sufficient to interrogate the role of Plk-2 inhibition inâ vivo. One such compound significantly decreased phosphorylation of α-synuclein in rat brain upon oral administration and represents a useful probe for future studies of this therapeutic avenue toward the potential treatment of Parkinson's disease.
Subject(s)
Brain/metabolism , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/antagonists & inhibitors , alpha-Synuclein/metabolism , Animals , Binding Sites , Blood-Brain Barrier/metabolism , Female , HEK293 Cells , Half-Life , Humans , Male , Mice , Molecular Dynamics Simulation , Phosphorylation/drug effects , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Protein Serine-Threonine Kinases/metabolism , Protein Structure, Tertiary , Rats , Rats, Sprague-DawleyABSTRACT
Polo-like kinase-2 (Plk-2) is a potential therapeutic target for Parkinson's disease and this Letter describes the SAR of a series of dihydropteridinone based Plk-2 inhibitors. By optimizing both the N-8 substituent and the biaryl region of the inhibitors we obtained single digit nanomolar compounds such as 37 with excellent selectivity for Plk-2 over Plk-1. When dosed orally in rats, compound 37 demonstrated a 41-45% reduction of pS129-α-synuclein levels in the cerebral cortex.
Subject(s)
Drug Design , Protein Kinase Inhibitors/chemical synthesis , Protein Serine-Threonine Kinases/antagonists & inhibitors , Administration, Oral , Animals , Brain/metabolism , Cell Cycle Proteins/antagonists & inhibitors , Cell Cycle Proteins/metabolism , HEK293 Cells , Half-Life , Humans , Mice , Microsomes, Liver/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacokinetics , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins/antagonists & inhibitors , Proto-Oncogene Proteins/metabolism , Pteridines/chemical synthesis , Pteridines/chemistry , Pteridines/pharmacokinetics , Rats , Structure-Activity Relationship , Polo-Like Kinase 1ABSTRACT
Tyrosine hydroxylase (TH) catalyses the rate-limiting step in the biosynthesis of catecholamines. TH expression is regulated in a tissue-specific manner during neuronal development and differentiation. Because of its key regulatory role in central and peripheral catecholamine synthesis, TH is associated with the pathogenesis of several neurological and psychiatric diseases, including Parkinson's disease, dystonia, schizophrenia, affective disorders, and cardiovascular diseases. Therefore, developing a quantitative method to monitor the changes in TH expression in disease models could facilitate the identification and characterisation of neuromodulatory and neuroprotective therapeutic agents. The present report describes the generation and characterisation of a new set of monoclonal TH antibodies and the development of a novel sandwich ELISA for the quantitative detection of the TH protein in rodent brain tissue. This ELISA exhibits excellent reproducibility and good linearity in the analysis of complex brain tissue lysates. The cross-validation of the TH ELISA using semi-quantitative TH Western blot methods and HPLC measurement of dopamine levels suggests that the new TH ELISA is sufficiently sensitive to detect small-to-moderate region-specific differences, developmental changes, and Parkinson's disease-related changes in TH expression in rodent brains. This new TH ELISA also offers greater flexibility than conventional HPLC-based dopamine assays because the optimal tissue lysis buffer used for the detection of TH in brain tissue is also compatible with the analysis of other proteins associated with Parkinson's disease, such as α-synuclein, suggesting that this TH ELISA could be used in a multiplexed format.
