ABSTRACT
The SAR of a series of brain penetrant, trisubstituted thiophene based JNK inhibitors with improved pharmacokinetic properties is described. These compounds were designed based on information derived from metabolite identification studies which led to compounds such as 42 with lower clearance, greater brain exposure and longer half life compared to earlier analogs.
Subject(s)
Brain/metabolism , Drug Design , Nerve Degeneration/prevention & control , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Thiophenes/pharmacology , Thiophenes/pharmacokinetics , Animals , Chemistry Techniques, Synthetic , Crystallography, X-Ray , Dose-Response Relationship, Drug , Half-Life , JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors , JNK Mitogen-Activated Protein Kinases/metabolism , Mice , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacokinetics , Stereoisomerism , Structure-Activity Relationship , Thiophenes/chemical synthesis , Thiophenes/chemistryABSTRACT
In this Letter, we describe the evolution of selective JNK3 inhibitors from 1, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs. Strong SAR was found for substitution of the naphthalene ring, as well as for inhibitors adopting different central scaffolds. Significant potency gains were appreciated by inverting the polarity of the thione of the parent triazolothione 1, resulting in potent compounds with attractive pharmacokinetic profiles.
Subject(s)
Enzyme Inhibitors/pharmacology , Mitogen-Activated Protein Kinase 10/antagonists & inhibitors , Naphthalenes/chemical synthesis , Thiones/chemical synthesis , Animals , Cells, Cultured , Enzyme Activation/drug effects , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Humans , Inhibitory Concentration 50 , Mice , Microsomes, Liver/enzymology , Molecular Structure , Naphthalenes/chemistry , Naphthalenes/pharmacology , Solubility , Structure-Activity Relationship , Thiones/chemistry , Thiones/pharmacologyABSTRACT
The SAR of a series of tri-substituted thiophene JNK3 inhibitors is described. By optimizing both the N-aryl acetamide region of the inhibitor and the 4-position of the thiophene we obtained single digit nanomolar compounds, such as 47, which demonstrated an in vivo effect on JNK activity when dosed orally in our kainic acid mouse model as measured by phospho-c-jun reduction.
Subject(s)
Brain/metabolism , MAP Kinase Kinase 4/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacokinetics , Administration, Oral , Drug Design , Hydrogen Bonding , Models, Molecular , Protein Kinase Inhibitors/chemical synthesis , Structure-Activity RelationshipABSTRACT
In this Letter, we describe the discovery of selective JNK2 and JNK3 inhibitors, such as 10, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs, p38α and ERK2. Substitution of the naphthalene ring affords an isoform selective JNK3 inhibitor, 30, with approximately 10-fold selectivity over both JNK1 and JNK2. A naphthalene ring penetrates deep into the selectivity pocket accounting for the differentiation amongst the kinases. Interestingly, the gatekeeper Met146 sulfide interacts with the naphthalene ring in a sulfur-π stacking interaction. Compound 38 ameliorates neurotoxicity induced by amyloid-ß in human cortical neurons. Lastly, we demonstrate how to install propitious in vitro CNS-like properties into these selective inhibitors.
Subject(s)
Aminopyridines/chemistry , Mitogen-Activated Protein Kinase 10/antagonists & inhibitors , Mitogen-Activated Protein Kinase 9/antagonists & inhibitors , Neurodegenerative Diseases/drug therapy , Neuroprotective Agents/chemistry , Protein Kinase Inhibitors/chemistry , Triazines/chemistry , Aminopyridines/pharmacokinetics , Aminopyridines/therapeutic use , Animals , Binding Sites , Central Nervous System/metabolism , Computer Simulation , Humans , Mice , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 10/metabolism , Mitogen-Activated Protein Kinase 9/metabolism , Neuroprotective Agents/pharmacokinetics , Neuroprotective Agents/therapeutic use , Protein Kinase Inhibitors/pharmacokinetics , Protein Kinase Inhibitors/therapeutic use , Structure-Activity Relationship , Triazines/pharmacokinetics , Triazines/therapeutic useABSTRACT
From high throughput screening, we discovered compound 1, the prototype for a series of disubstituted thiophene inhibitors of JNK which is selective towards closely related MAP kinases p38 and Erk2. Herein we describe the evolution of these compounds to a novel class of thiophene and thiazole JNK inhibitors that retain favorable solubility, permeability, and P-gp properties for development as CNS agents for treatment of neurodegeneration. Compound 61 demonstrated JNK3 IC(50)=77 nM and retained the excellent broad kinase selectivity observed for the series.
Subject(s)
JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors , Protein Kinase Inhibitors/chemical synthesis , Quinolines/chemical synthesis , Thiazoles/chemistry , Thiophenes/chemistry , Animals , Drug Design , Humans , JNK Mitogen-Activated Protein Kinases/metabolism , Mice , Microsomes, Liver/metabolism , Mitogen-Activated Protein Kinase 10/antagonists & inhibitors , Mitogen-Activated Protein Kinase 10/metabolism , Mitogen-Activated Protein Kinase 8/antagonists & inhibitors , Mitogen-Activated Protein Kinase 8/metabolism , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Quinolines/chemistry , Quinolines/pharmacology , Structure-Activity Relationship , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Thiophenes/chemical synthesis , Thiophenes/pharmacologyABSTRACT
Several neurological diseases, including Parkinson disease and dementia with Lewy bodies, are characterized by the accumulation of alpha-synuclein phosphorylated at Ser-129 (p-Ser-129). The kinase or kinases responsible for this phosphorylation have been the subject of intense investigation. Here we submit evidence that polo-like kinase 2 (PLK2, also known as serum-inducible kinase or SNK) is a principle contributor to alpha-synuclein phosphorylation at Ser-129 in neurons. PLK2 directly phosphorylates alpha-synuclein at Ser-129 in an in vitro biochemical assay. Inhibitors of PLK kinases inhibited alpha-synuclein phosphorylation both in primary cortical cell cultures and in mouse brain in vivo. Finally, specific knockdown of PLK2 expression by transduction with short hairpin RNA constructs or by knock-out of the plk2 gene reduced p-Ser-129 levels. These results indicate that PLK2 plays a critical role in alpha-synuclein phosphorylation in central nervous system.
Subject(s)
Central Nervous System/metabolism , Protein Kinases/metabolism , Serine/metabolism , alpha-Synuclein/metabolism , Animals , Base Sequence , Cell Line , Central Nervous System/enzymology , DNA Primers , Enzyme-Linked Immunosorbent Assay , Humans , Mice , Mice, Inbred C57BL , Mice, Knockout , Phosphorylation , Protein Serine-Threonine Kinases , RNA Interference , alpha-Synuclein/chemistryABSTRACT
Pathological hallmarks of Alzheimer's disease are the presence of extracellular amyloid plaques, intracellular neurofibrillary tangles, and neurodegeneration. The principal component of amyloid plaques is the amyloid-beta peptide (Abeta). Accumulating evidence indicates that Abeta may play a causal role in Alzheimer's disease. In this report, we demonstrate that Abeta deposition and neurotoxicity in human cortical primary neurons are mediated through alpha2beta1 and alphaVbeta1 integrins using specific integrin-blocking antibodies. An aberrant integrin signaling pathway causing the neurotoxicity is mediated through Pyk2. The role of alpha2beta1 and alphaVbeta1 integrins can be extended to another amyloidosis using an amylin in vitro neurotoxicity model. These results indicate that the alpha2beta1 and alphaVbeta1 integrin signaling pathway may be critical components of neurodegeneration in Alzheimer's disease and that integrins may recognize and be activated by a shared structural motif of polymerizing amyloidogenic proteins.
Subject(s)
Amyloid beta-Peptides/administration & dosage , Cerebral Cortex/metabolism , Cerebral Cortex/pathology , Integrin alpha2beta1/metabolism , Neurons/metabolism , Neurons/pathology , Signal Transduction/drug effects , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Apoptosis/drug effects , Cells, Cultured , Cerebral Cortex/drug effects , Dose-Response Relationship, Drug , Humans , Neurons/drug effects , Neurotoxins/administration & dosageABSTRACT
Accumulating evidence suggests that amyloid protein aggregation is pathogenic in many diseases, including Alzheimer's disease. However, the mechanisms by which protein aggregation mediates cellular dysfunction and overt cell death are unknown. Recent reports have focused on the potential role of amyloid oligomers or protofibrils as a neurotoxic form of amyloid-beta (Abeta) and related amyloid aggregates. Here we describe studies indicating that overt neuronal cell death mediated by Abeta(1-40) is critically dependent on ongoing Abeta(1-40) polymerization and is not mediated by a single stable species of neurotoxic aggregate. The extent and rate of neuronal cell death can be controlled by conditions that alter the rate of Abeta polymerization. The results presented here indicate that protofibrils and oligomeric forms of Abeta most likely generate neuronal cell death through a nucleation-dependent process rather than acting as direct neurotoxic ligands. These findings bring into question the use of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide formazan assay (MTT assay) as a reporter of Abeta-mediated neuronal cell death and suggest that diffusible Abeta protofibrils and oligomers more likely mediate subtle alterations of synaptic function and long-term potentiation rather than overt neuronal cell death. These results have been extended to Abeta(1-42), the non-Abeta component of Alzheimer's disease amyloid plaques, and human amylin, suggesting that nucleation-dependent polymerization is a common mechanism of amyloid-mediated neuronal cell death. Our findings indicate that ongoing amyloid fibrillogenesis may be an essential mechanistic process underlying the pathogenesis associated with protein aggregation in amyloid disorders.
