Discovery of Highly Potent, Selective, and Brain-Penetrant Aminopyrazole Leucine-Rich Repeat Kinase 2 (LRRK2) Small Molecule Inhibitors

The unlikely partnership between LRRK2 and α-synuclein in Parkinson's disease

Our understanding of the mechanisms underlying Parkinson's disease, the once archetypical nongenetic neurogenerative disorder, has dramatically increased with the identification of α-synuclein and LRRK2 pathogenic mutations. While α-synuclein protein composes the aggregates that can spread through much of the brain in disease, LRRK2 encodes a multidomain dual-enzyme distinct from any other protein linked to neurodegeneration. In this review, we discuss emergent datasets from multiple model systems that suggest these unlikely partners do interact in important ways in disease, both within cells that express both LRRK2 and α-synuclein as well as through more indirect pathways that might involve neuroinflammation. Although the link between LRRK2 and disease can be understood in part through LRRK2 kinase activity (phosphotransferase activity), α-synuclein toxicity is multilayered and plausibly interacts with LRRK2 kinase activity in several ways. We discuss common protein interactors like 14-3-3s that may regulate α-synuclein and LRRK2 in disease. Finally, we examine cellular pathways and outcomes common to both mutant α-synuclein expression and LRRK2 activity and points of intersection. Understanding the interplay between these two unlikely partners in disease may provide new therapeutic avenues for PD.

Discovery of potent and selective 5-azaindazole inhibitors of leucine-rich repeat kinase 2 (LRRK2) - Part 1

Parkinson's disease is a relatively common neurological disorder with incidence increasing with age. Present treatments merely alleviate the symptoms and do not alter the course of the disease, thus identification of disease modifying therapies represents a significant unmet medical need. Mutations in the LRRK2 gene are risk-factors for developing PD and it has been hypothesized that the increased kinase activity of certain LRRK2 mutants are responsible for the damage of the dopaminergic neurons, thus LRRK2 inhibitors offer the potential to target an underlying cause of the disease. In this communication, we describe hit-to-lead medicinal chemistry program on a novel series of 5-azaindazoles. Compound 1, obtained from high-throughput screening was optimized to a highly potent, selective series of molecules with promising DMPK properties. Introduction of heterocycles at the 3-position were found to significantly increase the potency and kinase selectivity, whilst changes to the 4-chlorobenzyl group improved the physicochemical properties. Our series was licensed to a major pharmaceutical company for further development.

Brain penetrant kinase inhibitors: Learning from kinase neuroscience discovery

A recent review of kinase inhibitors in clinical trials for brain cancer noted differences in the properties of these compounds relative to the mean property parameters associated with drugs marketed for CNS-associated conditions. However, many of these kinase drugs arose from opportunistic observations of brain activity, rather than design or flow schemes focused on optimizing CNS penetration. Thus, this digest examines kinase inhibitors that have been developed specifically for neurodegenerative indications such as Alzheimer's or Parkinson's disease, and considers design, flow scheme, and the physicochemical properties associated with compounds that have demonstrated brain penetrance.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

GTP binding regulates cellular localization of Parkinson's disease-associated LRRK2

Mutations in leucine-rich repeat kinase 2 (LRRK2) comprise the most common cause of familial Parkinson's disease (PD), and sequence variants modify risk for sporadic PD. Previous studies indicate that LRRK2 interacts with microtubules (MTs) and alters MT-mediated vesicular transport processes. However, the molecular determinants within LRRK2 required for such interactions have remained unknown. Here, we report that most pathogenic LRRK2 mutants cause relocalization of LRRK2 to filamentous structures which colocalize with a subset of MTs, and an identical relocalization is seen upon pharmacological LRRK2 kinase inhibition. The pronounced colocalization with MTs does not correlate with alterations in LRRK2 kinase activity, but rather with increased GTP binding. Synthetic mutations which impair GTP binding, as well as LRRK2 GTP-binding inhibitors profoundly interfere with the abnormal localization of both pathogenic mutant as well as kinase-inhibited LRRK2. Conversely, addition of a non-hydrolyzable GTP analog to permeabilized cells enhances the association of pathogenic or kinase-inhibited LRRK2 with MTs. Our data elucidate the mechanism underlying the increased MT association of select pathogenic LRRK2 mutants or of pharmacologically kinase-inhibited LRRK2, with implications for downstream MT-mediated transport events.

Synthesis and In Vitro and In Vivo Evaluation of [3H]LRRK2-IN-1 as a Novel Radioligand for LRRK2

PURPOSE

LRRK2 (leucine-rich repeat kinase 2) has recently been proven to be a promising drug target for Parkinson's disease (PD) due to an apparent enhanced activity caused by mutations associated with familial PD. To date, there have been no reports in which a LRRK2 inhibitor has been radiolabeled and used for in in vitro or in vivo studies of LRRK2. In the present study, we radiolabeled the LRRK2 ligand, LRRK-IN-1, for the purposes of performing in vitro (IC50, K d , B max, autoradiography) and in vivo (biodistribution, and blocking experiments) evaluations in rodents and human striatum tissues.

PROCEDURES

[3H]LRRK2-IN-1 was prepared with high radiochemical purity (>99 %) and a specific activity of 41 Ci/mmol via tritium/hydrogen (T/H) exchange using Crabtree's catalyst. For IC50, K d , and B max determination, LRRK2-IN-1 was used as a competing drug for nonspecific binding assessment. The specific binding of the tracer was further evaluated via an in vivo blocking study in mice with a potent LRRK2 inhibitor, Pf-06447475.

RESULTS

In vitro binding studies demonstrated a saturable binding site for [3H]LRRK2-IN-1 in rat kidney, rat brain striatum and human brain striatum with K d of 26 ± 3 and 43 ± 8, 48 ± 2 nM, respectively. In rat, the density of LRRK2 binding sites (B max) was higher in kidney (6.4 ± 0.04 pmol/mg) than in brain (2.5 ± 0.03 pmol/mg), however, in human brain striatum, the B max was 0.73 ± 0.01 pmol/mg protein. Autoradiography imaging in striatum of rat and human brain tissues gave results consistent with binding studies. In in vivo biodistribution and blocking studies in mice, co-administration with Pf-06447475 (10 mg/kg) reduced the uptake of [3H]LRRK2-IN-1 (%ID/g) by 50-60% in the kidney or brain.

CONCLUSION

The high LRRK2 brain density observed in our study suggests the feasibility for positron emission tomography imaging of LRRK2 (a potential target) with radioligands of higher affinity and specificity.

Selective LRRK2 kinase inhibition reduces phosphorylation of endogenous Rab10 and Rab12 in human peripheral mononuclear blood cells

Genetic variation in the leucine-rich repeat kinase 2 (LRRK2) gene is associated with risk of familial and sporadic Parkinson’s disease (PD). To support clinical development of LRRK2 inhibitors as disease-modifying treatment in PD biomarkers for kinase activity, target engagement and kinase inhibition are prerequisite tools. In a combined proteomics and phosphoproteomics study on human peripheral mononuclear blood cells (PBMCs) treated with the LRRK2 inhibitor Lu AF58786 a number of putative biomarkers were identified. Among the phospho-site hits were known LRRK2 sites as well as two phospho-sites on human Rab10 and Rab12. LRRK2 dependent phosphorylation of human Rab10 and human Rab12 at positions Thr73 and Ser106, respectively, was confirmed in HEK293 and, more importantly, Rab10-pThr73 inhibition was validated in immune stimulated human PBMCs using two distinct LRRK2 inhibitors. In addition, in non-stimulated human PBMCs acute inhibition of LRRK2 with two distinct LRRK2 inhibitor compounds reduced Rab10-Thr73 phosphorylation in a concentration-dependent manner with apparent IC₅₀’s equivalent to IC₅₀’s on LRRK2-pSer935. The identification of Rab10 phosphorylated at Thr73 as a LRRK2 inhibition marker in human PBMCs strongly support inclusion of assays quantifying Rab10-pThr73 levels in upcoming clinical trials evaluating LRRK2 kinase inhibition as a disease-modifying treatment principle in PD.

Targeting LRRK2 in Parkinson's disease: an update on recent developments

INTRODUCTION

LRRK2 research has progressed significantly in recent years with more reports of LRRK2 interactors and the development of more specific and sophisticated LRRK2 kinase inhibitors. Identification of bone fide LRRK2 substrates will provide new therapeutic targets in LRRK2-linked Parkinson's disease (PD). Areas covered: This review aims to put current LRRK2 research into perspective. Beginning with recent LRRK2 mammalian models employed for in vivo validation of LRRK2 substrates, followed by updates on reported LRRK2 interactors and their inferred mechanisms. Finally an overview of commonly used LRRK2 kinase inhibitors will be depicted. Expert opinion: Identification of LRRK2 non-kinase functions suggests the possibility of alternative LRRK2 drug target sites and these should be further explored. Studies on the effects of LRRK2 kinase inhibition on its non-kinase function and its self-regulatory role will provide further insights on its pathophysiologic mechanisms. Development of robust measurements of LRRK2 inhibitor efficacy will be required. These would include identification of specific imaging ligands or direct biochemical assays that can accurately capture its intrinsic activity. Testing of new therapeutic drug targets in both LRRK2 carriers and non LRRK2-linked patients will be important since their phenotype is similar.

Discovery of N-((3R,4R)-4-Fluoro-1-(6-((3-methoxy-1-methyl-1H-pyrazol-4-yl)amino)-9-methyl-9H-purin-2-yl)pyrrolidine-3-yl)acrylamide (PF-06747775) through Structure-Based Drug Design: A High Affinity Irreversible Inhibitor Targeting Oncogenic EGFR Mutants with Selectivity over Wild-Type EGFR

Mutant epidermal growth factor receptor (EGFR) is a major driver of non-small-cell lung cancer (NSCLC). Marketed first generation inhibitors, such as erlotinib, effect a transient beneficial response in EGFR mutant NSCLC patients before resistance mechanisms render these inhibitors ineffective. Secondary oncogenic EGFR mutations account for approximately 50% of relapses, the most common being the gatekeeper T790M substitution that renders existing therapies ineffective. The discovery of PF-06459988 (1), an irreversible pyrrolopyrimidine inhibitor of EGFR T790M mutants, was recently disclosed.1 Herein, we describe our continued efforts to achieve potency across EGFR oncogenic mutations and improved kinome selectivity, resulting in the discovery of clinical candidate PF-06747775 (21), which provides potent EGFR activity against the four common mutants (exon 19 deletion (Del), L858R, and double mutants T790M/L858R and T790M/Del), selectivity over wild-type EGFR, and desirable ADME properties. Compound 21 is currently being evaluated in phase-I clinical trials of mutant EGFR driven NSCLC.

Discovery of a 3-(4-Pyrimidinyl) Indazole (MLi-2), an Orally Available and Selective Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitor that Reduces Brain Kinase Activity

Leucine-rich repeat kinase 2 (LRRK2) is a large, multidomain protein which contains a kinase domain and GTPase domain among other regions. Individuals possessing gain of function mutations in the kinase domain such as the most prevalent G2019S mutation have been associated with an increased risk for the development of Parkinson's disease (PD). Given this genetic validation for inhibition of LRRK2 kinase activity as a potential means of affecting disease progression, our team set out to develop LRRK2 inhibitors to test this hypothesis. A high throughput screen of our compound collection afforded a number of promising indazole leads which were truncated in order to identify a minimum pharmacophore. Further optimization of these indazoles led to the development of MLi-2 (1): a potent, highly selective, orally available, brain-penetrant inhibitor of LRRK2.

Kinase targets in CNS drug discovery

Originally thought to be nondruggable, kinases represent attractive drug targets for pharmaceutical companies and academia. To date, there are over 40 kinase inhibitors approved by the US FDA, with 32 of these being small molecules, in addition to the three mammalian target of rapamycin inhibitor macrolides (sirolimus, temsirolimus and everolimus). Despite the rapid development of kinase inhibitors for cancer, presently none of these agents are approved for CNS indications. This mini perspective highlights selected kinase targets for CNS disorders, of which brain-permeable small-molecule inhibitors are reported, with demonstrated preclinical proof-of-concept efficacy. This is followed by a brief discussion on the key challenges of blood–brain barrier penetration and selectivity profiles in developing kinase inhibitors for CNS disorders.

Development of LRRK2 Inhibitors for the Treatment of Parkinson's Disease

Linkage and genome-wide association studies have identified a genetic risk locus for late-onset Parkinson's disease in chromosome 12, originally identified as PARK6. The causative gene was identified to code for a large multifunctional protein, LRRK2 (leucine-rich repeat kinase 2). The combined genetic and biochemical evidence supports a hypothesis in which the LRRK2 kinase function is causally involved in the pathogenesis of sporadic and familial forms of PD, and therefore that LRRK2 kinase inhibitors could be useful for treatment. Although LRRK2 has so far not been crystallised, the use of homology modelling and crystallographic surrogates has allowed the optimisation of chemical structures such that compounds of high selectivity with good brain penetration and appropriate pharmacokinetic properties are now available for understanding the biology of LRRK2 in vitro and in vivo. This chapter reviews LRRK2 biology, the structural biology of LRRK2 and gives an overview of inhibitors of LRRK2.

Small-Molecule Inhibitors of LRRK2

Mutations in the leucine-rich repeat kinase 2 (LRRK2) protein have been genetically and functionally linked to Parkinson's disease (PD). The kinase activity of LRRK2 is increased by pathogenic mutations; therefore, modulation of LRRK2 kinase activity by a selective small-molecule inhibitor has been proposed as a potentially viable treatment for Parkinson's disease. This chapter presents a historical overview of the development and bioactivity of several small-molecule LRRK2 inhibitors that have been used to inhibit LRRK2 kinase activity in vitro or in vivo. These compounds are important tools for understanding the cellular biology of LRRK2 and for evaluating the potential of LRRK2 inhibitors as disease-modifying PD therapies.

Screening for chemical modulators for LRRK2

After the discovery of leucine-rich repeat kinase 2 (LRRK2) as a risk factor for sporadic Parkinson's disease (PD) and mutations in LRRK2 as a cause of some forms of familial PD, there has been substantial interest in finding chemical modulators of LRRK2 function. Most of the pathogenic mutations in LRRK2 are within the enzymatic cores of the protein; therefore, many screens have focused on finding chemical modulators of this enzymatic activity. There are alternative screening approaches that could be taken to investigate compounds that modulate LRRK2 cellular functions. These screens are more often phenotypic screens. The preparation for a screen has to be rigorous and enable high-throughput accurate assessment of a compound's activity. The pipeline to beginning a drug screen and some LRRK2 inhibitor and phenotypic screens will be discussed.

LRRK2 inhibitors and their potential in the treatment of Parkinson's disease: current perspectives

Major advances in understanding how genetics underlies Parkinson's disease (PD) have provided new opportunities for understanding disease pathogenesis and potential new targets for therapeutic intervention. One such target is leucine-rich repeat kinase 2 (LRRK2), an enigmatic enzyme implicated in both familial and idiopathic PD risk. Both academia and industry have promoted the development of potent and selective inhibitors of LRRK2, and these are currently being employed to assess the safety and efficacy of such compounds in preclinical models of PD. This review examines the evidence that LRRK2 kinase activity contributes to the pathogenesis of PD and outlines recent progress on inhibitor development and early results from preclinical safety and efficacy testing. This review also looks at some of the challenges remaining for translation of LRRK2 inhibitors to the clinic, if indeed this is ultimately warranted. As a disease with no current cure that is increasing in prevalence in line with an aging population, there is much need for developing new treatments for PD, and targeting LRRK2 is currently a promising option.

Mitochondrial drug targets in neurodegenerative diseases

Growing evidence suggests that mitochondrial dysfunction is the main culprit in neurodegenerative diseases. Given the fact that mitochondria participate in diverse cellular processes, including energetics, metabolism, and death, the consequences of mitochondrial dysfunction in neuronal cells are inevitable. In fact, new strategies targeting mitochondrial dysfunction are emerging as potential alternatives to current treatment options for neurodegenerative diseases. In this review, we focus on mitochondrial proteins that are directly associated with mitochondrial dysfunction. We also examine recently identified small molecule modulators of these mitochondrial targets and assess their potential in research and therapeutic applications.

Recent advances in biomarkers for Parkinson's disease focusing on biochemicals, omics and neuroimaging

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, involving progressive loss of the nigro-striatal dopaminergic neurons. Cardinal symptoms including tremors, muscle rigidity, drooping posture, drooping, walking difficulty, and autonomic symptoms appear when a significant number of nigrostriatal dopaminergic neurons have already been destroyed. Hence, reliable biomarkers are needed for early and accurate diagnosis to measure disease progression and response to therapy. We review the current status of protein and small molecule biomarkers involved in oxidative stress, protein aggregation and inflammation etc. which are present in cerebrospinal fluid, human blood, urine or saliva. In recent years, advances in genomics, proteomics, metabolomics, and functional brain imaging techniques have led to new insights into the pathoetiology of PD. Further studies in the novel discovery of PD biomarkers will provide avenues to treat PD patients more effectively with few or no side effects.

LRRK2 Kinase Inhibition as a Therapeutic Strategy for Parkinson's Disease, Where Do We Stand?

One of the most promising therapeutic targets for potential disease-modifying treatment of Parkinson's disease (PD) is leucine-rich repeat kinase 2 (LRRK2). Specifically, targeting LRRK2's kinase function has generated a lot of interest from both industry and academia. This work has yielded several published studies showing the feasibility of developing potent, selective and brain permeable LRRK2 kinase inhibitors. The availability of these experimental drugs is contributing to filling in the gaps in our knowledge on the safety and efficacy of LRRK2 kinase inhibition. Recent studies of LRRK2 kinase inhibition in preclinical models point to potential undesired effects in peripheral tissues such as lung and kidney. Also, while strategies are now emerging to measure target engagement of LRRK2 inhibitors, there remains an important need to expand efficacy studies in preclinical models of progressive PD. Future work in the LRRK2 inhibition field must therefore be directed towards developing molecules and treatment regimens which demonstrate efficacy in mammalian models of disease in conditions where safety liabilities are reduced to a minimum.

Chemical Biology of Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitors

There is an urgent need for the development of Parkinson's disease (PD) treatments that can slow disease progression. The leucine-rich repeat kinase 2 (LRRK2) protein has been genetically and functionally linked to PD, and modulation of LRRK2 enzymatic activity has been proposed as a novel therapeutic strategy. In this review, we describe the bioactivity of selected small molecules that have been used to inhibit LRRK2 kinase activity in vitro or in vivo. These compounds are important tools for understanding the cellular biology of LRRK2 and for evaluating the potential of LRRK2 inhibitors as disease-modifying PD therapies.

Non-dopamine receptor ligands for the treatment of Parkinson's disease. Insight into the related chemical/property space

Extensive biochemical and clinical studies have increasingly recognized Parkinson's disease as a highly complex and multi-faceted neurological disorder having branched non-motor symptoms including sleep disorders, pain, constipation, psychosis, depression, and fatigue. A wide range of biological targets in the brain deeply implicated in this pathology resulted in a plethora of novel small-molecule compounds with promising activity. This review thoroughly describes the chemical space of non-dopamine receptor ligands in terms of diversity, isosteric/bioisosteric morphing, and molecular descriptors.

Cellular processes associated with LRRK2 function and dysfunction

Mutations in the leucine-rich repeat kinase 2 (LRRK2)-encoding gene are the most common cause of monogenic Parkinson's disease. The identification of LRRK2 polymorphisms associated with increased risk for sporadic Parkinson's disease, as well as the observation that LRRK2-Parkinson's disease has a pathological phenotype that is almost indistinguishable from the sporadic form of disease, suggested LRRK2 as the culprit to provide understanding for both familial and sporadic Parkinson's disease cases. LRRK2 is a large protein with both GTPase and kinase functions. Mutations segregating with Parkinson's disease reside within the enzymatic core of LRRK2, suggesting that modification of its activity impacts greatly on disease onset and progression. Although progress has been made since its discovery in 2004, there is still much to be understood regarding LRRK2's physiological and neurotoxic properties. Unsurprisingly, given the presence of multiple enzymatic domains, LRRK2 has been associated with a diverse set of cellular functions and signalling pathways including mitochondrial function, vesicle trafficking together with endocytosis, retromer complex modulation and autophagy. This review discusses the state of current knowledge on the role of LRRK2 in health and disease with discussion of potential substrates of phosphorylation and functional partners with particular emphasis on signalling mechanisms. In addition, the use of immune cells in LRRK2 research and the role of oxidative stress as a regulator of LRRK2 activity and cellular function are also discussed.

Studies on the synthesis, stability and conformation of 2-sulfonyl-oxetane fragments

A library of 2-sulfonyl oxetane fragments has been synthesised and elaborated into lead-like compounds. The oxetane derivatives were stable to acidic and basic conditions and have 3-preferred conformations.

Synthesis of polysubstituted 4-aminopyrazoles and 4-hydroxypyrazoles from vinyl azides and hydrazines

A simple and direct synthesis of polysubstituted 4-aminopyrazoles and 4-hydroxypyrazoles from vinyl azides and hydrazines.

Ten years and counting: moving leucine-rich repeat kinase 2 inhibitors to the clinic

The burden that Parkinson's disease (PD) exacts on the population continues to increase year after year. Though refinement of symptomatic treatments continues at a reasonable pace, no accepted therapies are available to slow or prevent disease progression. The leucine-rich repeat kinase 2 (LRRK2) gene was identified in PD genetic studies and offers new hope for novel therapeutic approaches. The evidence linking LRRK2 kinase activity to PD susceptibility is presented, as well as seminal discoveries relevant to the prosecution of LRRK2 kinase inhibition. Finally, suggestions are made for predictive preclinical modeling and successful first-in-human trials. © 2014 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Discovery and preclinical profiling of 3-[4-(morpholin-4-yl)-7H-pyrrolo[2,3-d]pyrimidin-5-yl]benzonitrile (PF-06447475), a highly potent, selective, brain penetrant, and in vivo active LRRK2 kinase inhibitor

Leucine rich repeat kinase 2 (LRRK2) has been genetically linked to Parkinson's disease (PD) by genome-wide association studies (GWAS). The most common LRRK2 mutation, G2019S, which is relatively rare in the total population, gives rise to increased kinase activity. As such, LRRK2 kinase inhibitors are potentially useful in the treatment of PD. We herein disclose the discovery and optimization of a novel series of potent LRRK2 inhibitors, focusing on improving kinome selectivity using a surrogate crystallography approach. This resulted in the identification of 14 (PF-06447475), a highly potent, brain penetrant and selective LRRK2 inhibitor which has been further profiled in in vivo safety and pharmacodynamic studies.

Synthesis of di-, tri-, and tetrasubstituted oxetanes by rhodium-catalyzed O-H insertion and C-C bond-forming cyclization

Oxetanes offer exciting potential as structural motifs and intermediates in drug discovery and materials science. Here an efficient strategy for the synthesis of oxetane rings incorporating pendant functional groups is described. A wide variety of oxetane 2,2-dicarboxylates were accessed in high yields, including functionalized 3-/4-aryl- and alkyl-substituted oxetanes and fused oxetane bicycles. Enantioenriched alcohols provided enantioenriched oxetanes with complete retention of configuration. The oxetane products were further derivatized, while the ring was maintained intact, thus highlighting their potential as building blocks for medicinal chemistry.

Genetic and pharmacological evidence that G2019S LRRK2 confers a hyperkinetic phenotype, resistant to motor decline associated with aging

The leucine-rich repeat kinase 2 mutation G2019S in the kinase-domain is the most common genetic cause of Parkinson's disease. To investigate the impact of the G2019S mutation on motor activity in vivo, a longitudinal phenotyping approach was developed in knock-in (KI) mice bearing this kinase-enhancing mutation. Two cohorts of G2019S KI mice and wild-type littermates (WT) were subjected to behavioral tests, specific for akinesia, bradykinesia and overall gait ability, at different ages (3, 6, 10, 15 and 19 months). The motor performance of G2019S KI mice remained stable up to the age of 19 months and did not show the typical age-related decline in immobility time and stepping activity of WT. Several lines of evidence suggest that enhanced LRRK2 kinase activity is the main contributor to the observed hyperkinetic phenotype of G2019S KI mice: i) KI mice carrying a LRRK2 kinase-dead mutation (D1994S KD) showed a similar progressive motor decline as WT; ii) two LRRK2 kinase inhibitors, H-1152 and Nov-LRRK2-11, acutely reversed the hyperkinetic phenotype of G2019S KI mice, while being ineffective in WT or D1994S KD animals. LRRK2 target engagement in vivo was further substantiated by reduction of LRRK2 phosphorylation at Ser935 in the striatum and cortex at efficacious doses of Nov-LRRK2-11, and in the striatum at efficacious doses of H-1152. In summary, expression of the G2019S mutation in the mouse LRRK2 gene confers a hyperkinetic phenotype that is resistant to age-related motor decline, likely via enhancement of LRRK2 kinase activity. This study provides an in vivo model to investigate the effects of LRRK2 inhibitors on motor function.

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The LRRK2 G2019S mutation confers a hyperkinetic phenotype.

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The LRRK2 D1994S kinase-dead mutation does not affect motor phenotype.

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The LRRK2 kinase inhibitors reverse motor phenotype of G2019S mice.

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The LRRK2 kinase inhibitors inhibit LRRK2 phosphorylation at Ser935 ex-vivo.