Small-Molecule Disruptors of the Interaction between Calcium- and Integrin-Binding Protein 1 and Integrin αIIbβ3 as Novel Antiplatelet Agents

Thrombosis, a key factor in most cardiovascular diseases, is a major contributor to human mortality. Existing antithrombotic agents carry a risk of bleeding. Consequently, there is a keen interest in discovering innovative antithrombotic agents that can prevent thrombosis without negatively impacting hemostasis. Platelets play crucial roles in both hemostasis and thrombosis. We have previously characterized calcium- and integrin-binding protein 1 (CIB1) as a key regulatory molecule that regulates platelet function. CIB1 interacts with several platelet proteins including integrin αIIbβ3, the major glycoprotein receptor for fibrinogen on platelets. Given that CIB1 regulates platelet function through its interaction with αIIbβ3, we developed a fluorescence polarization (FP) assay to screen for potential inhibitors. The assay was miniaturized to 1536-well and screened in quantitative high-throughput screening (qHTS) format against a diverse compound library of 14,782 compounds. After validation and selectivity testing using the FP assay, we identified 19 candidate inhibitors and validated them using an in-gel binding assay that monitors the interaction of CIB1 with αIIb cytoplasmic tail peptide, followed by testing of top hits by intrinsic tryptophan fluorescence (ITF) and microscale thermophoresis (MST) to ascertain their interaction with CIB1. Two of the validated hits shared similar chemical structures, suggesting a common mechanism of action. Docking studies further revealed promising interactions within the hydrophobic binding pocket of the target protein, particularly forming key hydrogen bonds with Ser180. The compounds exhibited a potent antiplatelet activity based on their inhibition of thrombin-induced human platelet aggregation, thus indicating that disruptors of the CIB1- αIIbβ3 interaction could carry a translational potential as antithrombotic agents.

Initial Molecular Mechanisms of the Pathogenesis of Parkinson's Disease in a Mouse Neurotoxic Model of the Earliest Preclinical Stage of This Disease

Studying the initial molecular mechanisms of the pathogenesis of Parkinson's disease (PD), primarily in the nigrostriatal dopaminergic system, is one of the priorities in neurology. Of particular interest is elucidating these mechanisms in the preclinical stage of PD, which lasts decades before diagnosis and is therefore not available for study in patients. Therefore, our main goal was to study the initial molecular mechanisms of the pathogenesis of PD in the striatum, the key center for dopamine regulation in motor function, in a mouse model of the earliest preclinical stage of PD, from 1 to 24 h after the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). It was shown that the content of tyrosine hydroxylase (TH), the first enzyme in dopamine synthesis, does not change within 6 h after the administration of MPTP, but decreases after 24 h. In turn, TH activity increases after 1 h, decreases after 3 h, remains at the control level after 6 h, and decreases 24 h after the administration of MPTP. The concentration of dopamine in the striatum gradually decreases after MPTP administration, despite a decrease in its degradation. The identified initial molecular mechanisms of PD pathogenesis are considered as potential targets for the development of preventive neuroprotective treatment.

Application of OpenArray Technology to Assess Changes in the Expression of Functionally Significant Genes in the Substantia Nigra of Mice in a Model of Parkinson's Disease

Studying the molecular mechanisms of the pathogenesis of Parkinson's disease (PD) is critical to improve PD treatment. We used OpenArray technology to assess gene expression in the substantia nigra (SN) cells of mice in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD and in controls. Among the 11 housekeeping genes tested, Rps27a was taken as the reference gene due to its most stable expression in normal and experimental conditions. From 101 genes encoding functionally significant proteins of nigrostriatal dopaminergic neurons, 57 highly expressed genes were selected to assess their expressions in the PD model and in the controls. The expressions of Th, Ddc, Maoa, Comt, Slc6a3, Slc18a2, Drd2, and Nr4a2 decreased in the experiment compared to the control, indicating decreases in the synthesis, degradation, and transport of dopamine and the impaired autoregulation of dopaminergic neurons. The expressions of Tubb3, Map2, Syn1, Syt1, Rab7, Sod1, Cib1, Gpx1, Psmd4, Ubb, Usp47, and Ctsb genes were also decreased in the MPTP-treated mice, indicating impairments of axonal and vesicular transport and abnormal functioning of the antioxidant and ubiquitin-proteasome systems in the SN. The detected decreases in the expressions of Snca, Nsf, Dnm1l, and Keap1 may serve to reduce pathological protein aggregation, increase dopamine release in the striatum, prevent mitophagy, and restore the redox status of SN cells.

Photo-oxygenation of histidine residue inhibits α-synuclein aggregation

Aggregation of α-synuclein (α-syn) into amyloid is the pathological hallmark of several neurodegenerative disorders, including Parkinson disease, dementia with Lewy bodies, and multiple system atrophy. It is widely accepted that α-syn aggregation is associated with neurodegeneration, although the mechanisms are not yet fully understood. Therefore, the inhibition of α-syn aggregation is a potential therapeutic approach against these diseases. This study used the photocatalyst for α-syn photo-oxygenation, which selectively adds oxygen atoms to fibrils. Our findings demonstrate that photo-oxygenation using this photocatalyst successfully inhibits α-syn aggregation, particularly by reducing its seeding ability. Notably, we also discovered that photo-oxygenation of the histidine at the 50th residue in α-syn aggregates is responsible for the inhibitory effect. These findings indicate that photo-oxygenation of the histidine residue in α-syn is a potential therapeutic strategy for synucleinopathies.

Soluble form of the APP fragment, sAPPβ, positively regulates tau secretion

Extracellular tau has been highlighted in the pathogenesis of Alzheimer disease (AD), which is the most common neurodegenerative disease. Pathological analyses as well as model animal studies suggest that amyloid-β peptide (Aβ) deposition facilitates the spreading of tau aggregation pathology via extracellular tau. However, the precise mechanism of tau secretion remains unknown. Here, we show that the overexpression of amyloid precursor protein (APP) enhances the secretion of tau phosphorylated at threonine 181 in mouse neuroblastoma Neuro2a cells. Moreover, we found that soluble amyloid precursor protein β (sAPPβ), which is generated by β-site APP cleaving enzyme 1 (BACE1), mediates tau secretion. Our results demonstrate that BACE1-mediated cleavage of APP plays pathological roles in AD pathogenesis by not only Aβ production, but by the spreading of tau aggregation pathology via sAPPβ in AD patients.

ADAMTS4 is involved in the production of the Alzheimer disease amyloid biomarker APP669-711

Amyloid-β (Aβ) deposition in the brain parenchyma is one of the pathological hallmarks of Alzheimer disease (AD). We have previously identified amyloid precursor protein (APP)669-711 (a.k.a. Aβ(-3)-40) in human plasma using immunoprecipitation combined with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (IP-MALDI-MS). Furthermore, we found that the level of a composite biomarker, i.e., a combination of APP669-711/Aβ1-42 ratio and Aβ1-40/Aβ1-42 ratio in human plasma, correlates with the amyloid PET status of AD patients. However, the production mechanism of APP669-711 has remained unclear. Using in vitro and in vivo assays, we identified A Disintegrin and Metalloproteinase with a Thrombospondin type 1 motif, type 4 (ADAMTS4) as a responsible enzyme for APP669-711 production. ADAMTS4 cleaves APP directly to generate the C-terminal stub c102, which is subsequently proteolyzed by γ-secretase to release APP669-711. Genetic knockout of ADAMTS4 reduced the production of endogenous APP669-711 by 30% to 40% in cultured cells as well as mouse plasma, irrespectively of Aβ levels. Finally, we found that the endogenous murine APP669-711/Aβ1-42 ratio was increased in aged AD model mice, which shows Aβ deposition as observed in human patients. These data suggest that ADAMTS4 is involved in the production of APP669-711, and a plasma biomarker determined by IP-MALDI-MS can be used to estimate the level of Aβ deposition in the brain of mouse models.

The power and the promise of CRISPR/Cas9 genome editing for clinical application with gene therapy

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Due to its high accuracy and efficiency, CRISPR/Cas9 techniques may provide a great chance to treat some gene-related diseases.

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Researchers used the CRISPR/Cas9 technique to cure or alleviate cancers through different approaches, such as gene therapy and immune therapy.

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The treatment of ocular diseases by Cas9 has entered into clinical phases.

Background

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is derived from the bacterial innate immune system and engineered as a robust gene-editing tool. Due to the higher specificity and efficiency of CRISPR/Cas9, it has been widely applied to many genetic and non-genetic disease, including cancers, genetic hemolytic diseases, acquired immunodeficiency syndrome, cardiovascular diseases, ocular diseases, and neurodegenerative diseases, and some X-linked diseases. Furthermore, in terms of the therapeutic strategy of cancers, many researchers used the CRISPR/Cas9 technique to cure or alleviate cancers through different approaches, such as gene therapy and immune therapy.

Aim of Review

Here, we conclude the recent application and clinical trials of CRISPR/Cas9 in non-cancerous diseases and cancers and pointed out some of the problems to be solved.

Key Scientific Concepts of Review

CRISPR/Cas9, derived from the microbial innate immune system, is developed as a robust gene-editing tool and has been applied widely. Due to its high accuracy and efficiency, CRISPR/Cas9 techniques may provide a great chance to treat some gene-related diseases by disrupting, inserting, correcting, replacing, or blocking genes for clinical application with gene therapy.

GPR120 Signaling Controls Amyloid-β Degrading Activity of Matrix Metalloproteinases

Alzheimer's disease (AD) is characterized by the extensive deposition of amyloid-β peptide (Aβ) in the brain. Brain Aβ level is regulated by a balance between Aβ production and clearance. The clearance rate of Aβ is decreased in the brains of sporadic AD patients, indicating that the dysregulation of Aβ clearance mechanisms affects the pathologic process of AD. Astrocytes are among the most abundant cells in the brain and are implicated in the clearance of brain Aβ via their regulation of the blood-brain barrier, glymphatic system, and proteolytic degradation. The cellular morphology and activity of astrocytes are modulated by several molecules, including ω3 polyunsaturated fatty acids, such as docosahexaenoic acid, which is one of the most abundant lipids in the brain, via the G protein-coupled receptor GPR120/FFAR4. In this study, we analyzed the role of GPR120 signaling in the Aβ-degrading activity of astrocytes. Treatment with the selective antagonist upregulated the matrix metalloproteinase (MMP) inhibitor-sensitive Aβ-degrading activity in primary astrocytes. Moreover, the inhibition of GPR120 signaling increased the levels of Mmp2 and Mmp14 mRNAs, and decreased the expression levels of tissue inhibitor of metalloproteinases 3 (Timp3) and Timp4, suggesting that GPR120 negatively regulates the astrocyte-derived MMP network. Finally, the intracerebral injection of GPR120-specific antagonist substantially decreased the levels of TBS-soluble Aβ in male AD model mice, and this effect was canceled by the coinjection of an MMP inhibitor. These data indicate that astrocytic GPR120 signaling negatively regulates the Aβ-degrading activity of MMPs.SIGNIFICANCE STATEMENT The level of amyloid β (Aβ) in the brain is a crucial determinant of the development of Alzheimer's disease. Here we found that astrocytes, which are the most abundant cell type in the CNS, harbor degrading activity against Aβ, which is regulated by GPR120 signaling. GPR120 is involved in the inflammatory response and obesity in peripheral organs. However, the pathophysiological role of GPR120 in Alzheimer's disease remains unknown. We found that selective inhibition of GPR120 signaling in astrocytes increased the Aβ-degrading activity of matrix metalloproteases. Our results suggest that GPR120 in astrocytes is a novel therapeutic target for the development of anti-Aβ therapeutics.

Genetic dependency of Alzheimer's disease-associated genes across cells and tissue types

Effective treatments targeting disease etiology are urgently needed for Alzheimer's disease (AD). Although candidate AD genes have been identified and altering their levels may serve as therapeutic strategies, the consequence of such alterations remain largely unknown. Herein, we analyzed CRISPR knockout/RNAi knockdown screen data for over 700 cell lines and evaluated cellular dependencies of 104 AD-associated genes previously identified by genome-wide association studies (GWAS) and gene expression network studies. Multiple genes showed widespread cell dependencies across tissue lineages, suggesting their inhibition may yield off-target effects. Meanwhile, several genes including SPI1, MEF2C, GAB2, ABCC11, ATCG1 were identified as genes of interest since their genetic knockouts specifically affected high-expressing cells whose tissue lineages are relevant to cell types found in AD. Overall, analyses of genetic screen data identified AD-associated genes whose knockout or knockdown selectively affected cell lines of relevant tissue lineages, prioritizing targets for potential AD treatments.

Photo-oxygenation by a biocompatible catalyst reduces amyloid-β levels in Alzheimer's disease mice

Amyloid formation and the deposition of the amyloid-β peptide are hallmarks of Alzheimer's disease pathogenesis. Immunotherapies using anti-amyloid-β antibodies have been highlighted as a promising approach for the prevention and treatment of Alzheimer's disease by enhancing microglial clearance of amyloid-β peptide. However, the efficiency of antibody delivery into the brain is limited, and therefore an alternative strategy to facilitate the clearance of brain amyloid is needed. We previously developed an artificial photo-oxygenation system using a low molecular weight catalytic compound. The photocatalyst specifically attached oxygen atoms to amyloids upon irradiation with light, and successfully reduced the neurotoxicity of aggregated amyloid-β via inhibition of amyloid formation. However, the therapeutic effect and mode of actions of the photo-oxygenation system in vivo remained unclear. In this study, we demonstrate that photo-oxygenation facilitates the clearance of aggregated amyloid-β from the brains of living Alzheimer's disease model mice, and enhances the microglial degradation of amyloid-β peptide. These results suggest that photo-oxygenation may represent a novel anti-amyloid-β strategy in Alzheimer's disease, which is compatible with immunotherapy.

EphA4 regulates Aβ production via BACE1 expression in neurons

Several lines of evidence suggest that the aggregation and deposition of amyloid-β peptide (Aβ) initiate the pathology of Alzheimer's disease (AD). Recently, a genome-wide association study demonstrated that a single-nucleotide polymorphism proximal to the EPHA4 gene, which encodes a receptor tyrosine kinase, is associated with AD risk. However, the molecular mechanism of EphA4 in the pathogenesis of AD, particularly in Aβ production, remains unknown. Here, we performed several pharmacological and biological experiments both in vitro and in vivo and demonstrated that EphA4 is responsible for the regulation of Aβ production. Pharmacological inhibition of EphA4 signaling and knockdown of Epha4 led to increased Aβ levels accompanied by increased expression of β-site APP cleaving enzyme 1 (BACE1), which is an enzyme responsible for Aβ production. Moreover, EPHA4 overexpression and activation of EphA4 signaling via ephrin ligands decreased Aβ levels. In particular, the sterile-alpha motif domain of EphA4 was necessary for the regulation of Aβ production. Finally, EPHA4 mRNA levels were significantly reduced in the brains of AD patients, and negatively correlated with BACE1 mRNA levels. Our results indicate a novel mechanism of Aβ regulation by EphA4, which is involved in AD pathogenesis.

CRISPR/Cas gene therapy

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated enzyme (Cas) is a naturally occurring genome editing tool adopted from the prokaryotic adaptive immune defense system. Currently, CRISPR/Cas9-based genome editing has been becoming one of the most promising tools for treating human genetic diseases, including cardiovascular diseases, neuro-disorders, and cancers. As the quick modification of the CRISPR/Cas9 system, including delivery system, CRISPR/Cas9-based gene therapy has been extensively studied in preclinic and clinic treatments. CRISPR/Cas genome editing is also a robust tool to create animal genetic models for studying and treating human genetic disorders, particularly diseases associated with point mutations. However, significant challenges also remain before CRISPR/Cas technology can be routinely employed in the clinic for treating different genetic diseases, which include toxicity and immune response of treated cells to CRISPR/Cas component, highly throughput delivery method, and potential off-target impact. The off-target effect is one of the major concerns for CRISPR/Cas9 gene therapy, more research should be focused on limiting this impact by designing high specific gRNAs and using high specificity of Cas enzymes. Modifying the CRISPR/Cas9 delivery method not only targets a specific tissue/cell but also potentially limits the off-target impact.

Advances in Genomics for Drug Development

Drug development (target identification, advancing drug leads to candidates for preclinical and clinical studies) can be facilitated by genetic and genomic knowledge. Here, we review the contribution of population genomics to target identification, the value of bulk and single cell gene expression analysis for understanding the biological relevance of a drug target, and genome-wide CRISPR editing for the prioritization of drug targets. In genomics, we discuss the different scope of genome-wide association studies using genotyping arrays, versus exome and whole genome sequencing. In transcriptomics, we discuss the information from drug perturbation and the selection of biomarkers. For CRISPR screens, we discuss target discovery, mechanism of action and the concept of gene to drug mapping. Harnessing genetic support increases the probability of drug developability and approval.