Impaired virtual space-tilting perception in Parkinson's disease with Pisa syndrome

INTRODUCTION

The mechanism of Pisa syndrome in Parkinson's disease (PD) is unclear. We aimed to analyze the spatial perception of patients with PD with Pisa syndrome using virtual reality.

METHODS

In total, 16 patients with Pisa syndrome, 16 age-matched patients without Pisa syndrome, and 16 age-matched controls were included. They viewed the virtual room gradually tilting to different 8 directions randomized across trials. The 75% discrimination threshold angle and the mean tilting discrimination angle for each direction were evaluated. Participants' lateral trunk deviation was measured using Kinect. Neuropsychological status was evaluated, using the Mini-Mental Status Examination (MMSE), the Japanese version of the Montreal-Cognitive Assessment, Frontal Assessment Battery, and the color-word interference task of the Stroop test. Visuospatial abilities were assessed using Benton Judgement of Line Orientation, and vestibular function was evaluated using Subjective Visual Vertical (SVV).

RESULTS

The 75% discrimination threshold in the tilting discrimination angle was larger in all directions for those in the Pisa syndrome group compared to patients in the without Pisa syndrome group and those in the control group. There were significant differences between the three groups for Front-Right, Right, and Back. Patients with Pisa syndrome showed a significantly worse performance in these tests compared with controls and tended to have worse SVV performance compared with patients without Pisa syndrome.

CONCLUSION

The present findings support the hypothesis of visuo-spatial disability and/or attentional impairment in patients with Pisa syndrome.

Identification of α-Synuclein Proaggregator: Rapid Synthesis and Streamlining RT-QuIC Assays in Parkinson’s Disease

We report the discovery of two compounds, TKD150 and TKD152, that promote the aggregation of α-synuclein (aSN) using a real-time quaking-induced conversion (RT-QuIC) assay to detect abnormal aSN. By utilizing a Pd-catalyzed C–H arylation of benzoxazole with iodoarenes and implementing a planar conformation to the design, we successfully identified TKD150 and TKD152 as proaggregators for aSN. In comparison to a previously reported proaggregator, PA86, the two identified compounds were able to promote aggregation of aSN at twice the rate. Application of TKD150 and TKD152 to the RT-QuIC assay will shorten the inherent lag time and may allow wider use of this assay in clinical settings for the diagnosis of α-synucleinopathy-related diseases.

Quantitative comparison of the mRNA content of human iPSC-derived motor neurons and their extracellular vesicles

Extracellular vesicles (EVs) contain various cargo molecules, including RNAs and proteins. EVs, which include exosomes, are predicted to be suitable surrogates of their source cells for liquid biopsy to measure biomarkers. Several studies have performed qualitative comparisons of cargo molecule repertoires between source cells and their EVs. However, quantitative comparisons have not been reported so far. Furthermore, many studies analyzed microRNAs or proteins in EVs, but not mRNAs. In this study, we analyzed mRNAs in motor neurons and their EVs. Normal human-induced pluripotent stem cells were differentiated into motor neurons, and comprehensive analysis of mRNAs in the cells and their EVs was performed by RNA sequencing. Differential analysis between cellular and EV mRNAs was performed by edgeR after normalization of read count. The results suggest that signatures in the abundance of EV mRNAs were different from those of cellular mRNAs. Comparison of intracellular vesicle and EV mRNA abundance showed negatively and positively biased genes in the EVs. Gene Ontology analysis revealed that the genes showing negatively biased abundance in the EVs were enriched in many functions regarding neuronal development. In contrast, the positively biased genes were enriched in functions regarding cellular metabolism and protein synthesis. These results suggest that mRNAs in motor neurons are loaded into EVs to regulate certain mechanisms, which are yet to be elucidated.

Design and Identification of a GPR40 Full Agonist () Possessing a 2-Carbamoylphenyl Piperidine Moiety

GPR40/FFAR1 is a G-protein-coupled receptor expressed in pancreatic β-cells and enteroendocrine cells. GPR40 activation stimulates secretions of insulin and incretin, both of which are the pivotal regulators of glycemic control. Therefore, a GPR40 agonist is an attractive target for the treatment of type 2 diabetes mellitus. Using the reported biaryl derivative 1, we shifted the hydrophobic moiety to the terminal aryl ring and replaced the central aryl ring with piperidine, generating 2-(4,4-dimethylpentyl)phenyl piperidine 4a, which had improved potency for GPR40 and high lipophilicity. We replaced the hydrophobic moiety with N-alkyl-N-aryl benzamides to lower the lipophilicity and restrict the N-alkyl moieties to the presumed lipophilic pocket using the intramolecular π-π stacking of cis-preferential N-alkyl-N-aryl benzamide. Among these, orally available (3S)-3-cyclopropyl-3-(2-((1-(2-((2,2-dimethylpropyl)(6-methylpyridin-2-yl)carbamoyl)-5-methoxyphenyl)piperidin-4-yl)methoxy)pyridin-4-yl)propanoic acid (SCO-267) effectively stimulated insulin secretion and GLP-1 release and ameliorated glucose tolerance in diabetic rats via GPR40 full agonism.

Structure-based rational design of staurosporine-based fluorescent probe with broad-ranging kinase affinity for kinase panel application

Selectivity profiling of compounds is important for kinase drug discovery. To this end, we aimed to develop a broad-range protein kinase assay by synthesizing a novel staurosporine-derived fluorescent probe based on staurosporine and kinase-binding related structural information. Upon structural analysis of staurosporine with kinases, a 4'-methylamine moiety of staurosporine was found to be located on the solvent side of the kinases, to which several linker units can be conjugated by either alkylation or acylation. However, such conjugation was suggested to reduce the binding affinities of the modified compound for several kinases, owing to the elimination of hydrogen bond donor moiety of NH-group from 4'-methylamine and/or steric hindrance by acyl moiety. Based on this structural information, we designed and synthesized a novel staurosporine-based probe without methyl group in order to retain the hydrogen bond donor, similar to unmodified staurosporine. The broad range of the kinase binding assay demonstrated that our novel fluorescent probe is an excellent tool for developing broad-ranging kinase binding assay.

Small-Scale Panel Comprising Diverse Gene Family Targets To Evaluate Compound Promiscuity

Despite the recent advances in the life sciences and the remarkable investment in drug discovery research, the success rate of small-molecule drug development remains low. Safety is the second most influential factor of drug attrition in clinical studies; thus, the selection of compounds with fewer toxicity concerns is crucial to increase the success rate of drug discovery. Compounds that promiscuously bind to multiple targets are likely to cause unexpected pharmacological activity that may lead to adverse effects. Therefore, avoiding such compounds during early research stages would contribute to identifying compounds with a higher chance of success in the clinic. To evaluate the interaction profile against a wide variety of targets, we constructed a small-scale promiscuity panel (PP) consisting of eight targets (ROCK1, PDE4D2, GR, PPARγ, 5-HT_2B, adenosine A₃, M1, and GABA_A) that were selected from diverse gene families. The validity of this panel was confirmed by comparison with the promiscuity index evaluated from larger-scale panels. Analysis of data from the PP revealed that both lipophilicity and basicity are likely to increase promiscuity, while the molecular weight does not significantly contribute. Additionally, the promiscuity assessed using our PP correlated with the occurrence of both in vitro cytotoxicity and in vivo toxicity, suggesting that the PP is useful to identify compounds with fewer toxicity concerns. In summary, this small-scale and cost-effective PP can contribute to the identification of safer compounds that would lead to a reduction in drug attrition due to safety issues.

Identification of biomarkers for amyotrophic lateral sclerosis by comprehensive analysis of exosomal mRNAs in human cerebrospinal fluid

Background

Exosomes are a subset of extracellular vesicles 30–200 nm in diameter secreted from cells, which contain functional mRNAs and microRNAs. Cerebrospinal fluid (CSF) is the primary source for liquid biopsy to examine diseases in central nervous system. To date, there is no available method to analyze exosomal mRNAs comprehensively in human CSF.

Methods

The main purpose of this study is to established the methodology of comprehensive analysis of exosomal mRNAs in CSF by a highly sensitive next-generation sequencing. The signatures of CSF exosomal mRNAs were then compared between four normal healthy donors and four sporadic amyotrophic lateral sclerosis patients to identify disease-related biomarkers. Differentially expressed genes were identified by DESeq2.

Results

RNA sequencing from CSF exosomes was successfully performed, that was demonstrated by the high pearson’s product-moment correlation coefficient (r = 0.993) in the technical replicates. Also, position coverage analysis revealed that most detected mRNAs retained their integrity throughout their full-length in CSF exosomes. In CSF exosomes from normal healthy donors, an average of 14,807 genes were detected, of which 4580 genes were commonly detected among four individuals, including neuron-enriched genes such as TUBB3 and CAMK2A. In comparison with exosomal mRNAs in CSF from four patients with amyotrophic lateral sclerosis, 543 genes were significantly changed, as represented by CUEDC2. Gene Ontology analysis and pathway analysis with these genes revealed functional enrichment of ubiquitin-proteasome pathway, oxidative stress response, and unfolded protein response. These pathways are related to pathomechanisms of amyotrophic lateral sclerosis.

Conclusion

We successfully established the methodology of comprehensive analysis of exosomal mRNAs in human CSF. It was shown to be useful to identify disease biomarkers for central nervous system. Several genes, such as CUEDC2, in CSF exosomes were suggested to be candidate disease biomarkers for amyotrophic lateral sclerosis.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0473-z) contains supplementary material, which is available to authorized users.

Generating thermostabilized agonist-bound GPR40/FFAR1 using virus-like particles and a label-free binding assay

Elucidating the detailed mechanism of activation of membrane protein receptors and their ligand binding is essential for structure-based drug design. Membrane protein crystal structure analysis successfully aids in understanding these fundamental molecular interactions. However, protein crystal structure analysis of the G-protein-coupled receptor (GPCR) remains challenging, even for the class of GPCRs which have been included in the majority of structure analysis reports among membrane proteins, due to the substantial instability of these receptors when extracted from lipid bilayer membranes. It is known that increased thermostability tends to decrease conformational flexibility, which contributes to the generation of diffraction quality crystals. However, this is still not straightforward, and significant effort is required to identify thermostabilized mutants that are optimal for crystallography. To address this issue, a versatile screening platform based on a label-free ligand binding assay combined with transient overexpression in virus-like particles was developed. This platform was used to generate thermostabilized GPR40 [also known as free fatty acid receptor 1 (FFAR1)] for fasiglifam (TAK-875). This demonstrated that the thermostabilized mutant GPR40 (L42A/F88A/G103A/Y202F) was successfully used for crystal structure analysis.