Intrinsic targeting of host RNA by Cas13 constrains its utility.

Cas13 can be used for the knockdown, editing, imaging or detection of RNA and for RNA-based gene therapy. Here by using RNA immunoprecipitation sequencing, transcriptome profiling, biochemical analysis, high-throughput screening and machine learning, we show that Cas13 can intrinsically target host RNA in mammalian cells through previously unappreciated mechanisms. Different from its known cis/trans RNA-cleavage activity, Cas13 can also cleave host RNA via mechanisms that are transcript-specific, independent of the sequence of CRISPR RNA and dynamically dependent on the conformational state of Cas13, as we show for several Cas13-family effectors encoded in one-vector and two-vector lentiviral systems. Moreover, host genes involved in viral processes and whose transcripts are intrinsically targeted by Cas13 contribute to constraining the lentiviral delivery and expression of Cas13. Our findings offer guidance for the appropriate use of lentiviral Cas13 systems and highlight the need for caution regarding intrinsic RNA targeting in Cas13-based applications.

A deep learning-based drug repurposing screening and validation for anti-SARS-CoV-2 compounds by targeting the cell entry mechanism.

The recent outbreak of Corona Virus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a severe threat to the global public health and economy, however, effective drugs to treat COVID-19 are still lacking. Here, we employ a deep learning-based drug repositioning strategy to systematically screen potential anti-SARS-CoV-2 drug candidates that target the cell entry mechanism of SARS-CoV-2 virus from 2635 FDA-approved drugs and 1062 active ingredients from Traditional Chinese Medicine herbs. In silico molecular docking analysis validates the interactions between the top compounds and host receptors or viral spike proteins. Using a SARS-CoV-2 pseudovirus system, we further identify several drug candidates including Fostamatinib, Linagliptin, Lysergol and Sophoridine that can effectively block the cell entry of SARS-CoV-2 variants into human lung cells even at a nanomolar scale. These efforts not only illuminate the feasibility of applying deep learning-based drug repositioning for antiviral agents by targeting a specified mechanism, but also provide a valuable resource of promising drug candidates or lead compounds to treat COVID-19.

NRF-2/HO-1 Pathway-Mediated SHOX2 Activation Is a Key Switch for Heart Rate Acceleration by Yixin-Fumai Granules.

Population aging has led to increased sick sinus syndrome (SSS) incidence; however, no effective and safe medical therapy has been reported thus far. Yixin-Fumai granules (YXFMs), a Chinese medicine granule designed for bradyarrhythmia treatment, can effectively increase SSS patients' heart rate. Senescence-induced sinoatrial node (SAN) degeneration is an important part of SSS pathogenesis, and older people often show high levels of oxidative stress; reactive oxygen species (ROS) accumulation in the SAN causes abnormal SAN pacing or conduction functions. The current study observed the protective effects of YXFMs on senescent SAN and explored the relationship between the NRF-2/HO-1 pathway, SHOX2, and T-type calcium channels. We selected naturally senescent C57BL/6 mice with bradycardia to simulate SSS; electrocardiography, Masson's trichrome staining, and DHE staining were used to assess SAN function and tissue damage. Immunofluorescence staining and Western blotting were used to assay related proteins. In vitro, we treated human-induced pluripotent stem cell-derived atrial myocytes (hiPSC-AMs) and mouse atrial myocyte-derived cell line HL-1 with D-galactose to simulate senescent SAN-pacemaker cells. CardioExcyte96 was used to evaluate the pulsatile function of the hiPSC-AMs, and the mechanism was verified by DCFH-DA, immunofluorescence staining, RT-qPCR, and Western blotting. The results demonstrated that YXFMs effectively inhibited senescence-induced SAN hypofunction, and this effect possibly originated from scavenging of ROS and promotion of NRF-2, SHOX2, and T-type calcium channel expression. In vitro experiment results indicated that ML385, si-SHOX2, LDN193189, and Mibefradil reversed YXFMs' effects. Moreover, we, for the first time, found that ROS accumulation may hinder SHOX2 expression; YXFMs can activate SHOX2 through the NRF-2/HO-1 pathway-mediated ROS scavenging and then regulate CACNA1G through the SHOX2/BMP4/GATA4/NKX2-5 axis, improve T-type calcium channel function, and ameliorate the SAN dysfunction. Finally, through network pharmacology and molecular docking, we screened for the most stable YXFMs compound that docks to NRF-2, laying the foundation for future studies.

A chemical-enhanced system for CRISPR-Based nucleic acid detection.

The CRISPR-based nucleic acid detection systems have shown great potential for point-of-care testing of viral pathogens, especially in the context of COVID-19 pandemic. Here we optimize several key parameters of reaction chemistry and develop a Chemical Enhanced CRISPR Detection system for nucleic acid (termed CECRID). For the Cas12a/Cas13a-based signal detection phase, we determine buffer conditions and substrate range for optimal detection performance, and reveal a crucial role of bovine serum albumin in enhancing trans-cleavage activity of Cas12a/Cas13a effectors. By comparing several chemical additives, we find that addition of L-proline can secure or enhance Cas12a/Cas13a detection capability. For isothermal amplification phase with typical LAMP and RPA methods, inclusion of L-proline can also enhance specific target amplification as determined by CRISPR detection. Using SARS-CoV-2 pseudovirus, we demonstrate CECRID has enhanced detection sensitivity over chemical additive-null method with either fluorescence or lateral flow strip readout. Thus, CECRID provides an improved detection power and system robustness, and helps to develop enhanced reagent formula or test kit towards practical application of CRISPR-based diagnostics.

An in silico drug repositioning workflow for host-based antivirals.

Drug repositioning represents a cost- and time-efficient strategy for drug development. Artificial intelligence-based algorithms have been applied in drug repositioning by predicting drug-target interactions in an efficient and high throughput manner. Here, we present a workflow of in silico drug repositioning for host-based antivirals using specially defined targets, a refined list of drug candidates, and an easily implemented computational framework. The workflow described here can also apply to more general purposes, especially when given a user-defined druggable target gene set. For complete details on the use and execution of this protocol, please refer to Li et al. (2021).

A computational framework of host-based drug repositioning for broad-spectrum antivirals against RNA viruses.

RNA viruses are responsible for many zoonotic diseases that post great challenges for public health. Effective therapeutics against these viral infections remain limited. Here, we deployed a computational framework for host-based drug repositioning to predict potential antiviral drugs from 2,352 approved drugs and 1,062 natural compounds embedded in herbs of traditional Chinese medicine. By systematically interrogating public genetic screening data, we comprehensively cataloged host dependency genes (HDGs) that are indispensable for successful viral infection corresponding to 10 families and 29 species of RNA viruses. We then utilized these HDGs as potential drug targets and interrogated extensive drug-target interactions through database retrieval, literature mining, and de novo prediction using artificial intelligence-based algorithms. Repurposed drugs or natural compounds were proposed against many viral pathogens such as coronaviruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), flaviviruses, and influenza viruses. This study helps to prioritize promising drug candidates for in-depth evaluation against these virus-related diseases.

Transferrin-Modified Osthole PEGylated Liposomes Travel the Blood-Brain Barrier and Mitigate Alzheimer's Disease-Related Pathology in APP/PS-1 Mice.

INTRODUCTION: Osthole (Ost) is a coumarin compound that strengthens hippocampal neurons and neural stem cells against Aß oligomer-induced neurotoxicity in mice, and is a potential drug for the treatment of Alzheimer's disease (AD). However, the effectiveness of the drug is limited by its solubility and bioavailability, as well as by the low permeability of the blood-brain barrier (BBB). In this study, a kind of transferrin-modified Ost liposomes (Tf-Ost-Lip) was constructed, which could improve the bioavailability and enhance brain targeting. METHODS: Tf-Ost-Lip was prepared by thin-film hydration method. The ability of liposomal formulations to translocate across BBB was investigated using in vitro BBB model. And the protective effect of Tf-Ost-Lip was evaluated in APP-SH-SY5Y cells. In addition, we performed pharmacokinetics study and brain tissue distribution analysis of liposomal formulations in vivo. We also observed the neuroprotective effect of the varying formulations in APP/PS-1 mice. RESULTS: In vitro studies reveal that Tf-Ost-Lip could increase the intracellular uptake of hCMEC/D3 cells and APP-SH-SY5Y cells, and increase the drug concentration across the BBB. Additionally, Tf-Ost-Lip was found to exert a protective effect on APP-SH-SY5Y cells. In vivo studies of pharmacokinetics and the Ost distribution in brain tissue indicate that Tf-Ost-Lip prolonged the cycle time in mice and increased the accumulation of Ost in the brain. Furthermore, Tf-Ost-Lip was also found to enhance the effect of Ost on the alleviation of Alzheimer's disease-related pathology. CONCLUSION: Transferrin-modified liposomes for delivery of Ost has great potential for AD treatment.

Osthole alleviates inflammation by down-regulating NF-κB signaling pathway in traumatic brain injury.

Traumatic brain injury (TBI) is a common neurotrosis disorder of the central nervous system (CNS), which has dramatic consequences on the integrity of damaged tissue. In this study, we investigated the neuroprotective effect and anti-inflammatory actions of osthole, a natural coumarin derivative, in both in vivo and in vitro TBI models. We first prepared a mouse model of cortical stab wound brain injury, investigated the capacity for osthole to prevent secondary brain injury and further examined the underlying mechanism. We revealed that osthole significantly improved the neurological function, increased the number of neurons beside injured site. Additionally, osthole treatment reduced the expression of microglia and glial scar, lowered the level of the proinflammatory cytokines interleukin (IL)-6, IL-1ß, and tumor necrosis factor-α (TNF-α), and blocked the activation of nuclear factor kappa B (NF-κB). Furthermore, the protective effect of osthole was also examined in SH-SY5Y cells subjected to scratch injury. Treatment of osthole prominently suppressed cell apoptosis and inflammatory factors release by blocking injury-induced IκB-α phosphorylation and NF-κB translocation, and upregulated the IκB-α which functions in the NF-κB signaling pathway of SH-SY5Y cells. However, NF-κB signaling pathway was inhibited by pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor, the anti-inflammatory effect of osthole was abolished. In conclusion, our findings demonstrated that osthole attenuated inflammatory response by inhibiting the NF-κB pathway in TBI.

RETRACTED: Osthole attenuates APP-induced Alzheimer's disease through up-regulating miRNA-101a-3p.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editor-in-Chief. The journal was initially contacted by the corresponding author to request the retraction of the article because the "same pictures were confused" in Figure 3B. The further investigation of the editor found that Dr. Elisabeth Bik has pointed out some problems of this article, including similarities between features and sections of panels within Figures 3A and 3B, as well as between Western Blots within Figures 6A,B, 8C and 10A,B, and therefore the Editor has decided to retract the article.

Panaxadiol inhibits synaptic dysfunction in Alzheimer's disease and targets the Fyn protein in APP/PS1 mice and APP-SH-SY5Y cells.

AIM: Alzheimer's disease (AD), a neurodegenerative disease, is characterized by memory loss and synaptic damage. Up to now, there are limited drugs to cure or delay the state of this illness. Recently, the Fyn tyrosine kinase is implicated in AD pathology triggered by synaptic damage. Thus, Fyn inhibition may prevent or delay the AD progression. Therefore, in this paper, we investigated whether Panaxadiol could decrease synaptic damage in AD and the underlying mechanism. MAIN METHODS: The ability of learning and memory of mice has detected by Morris Water Maze. The pathological changes detected by H&E staining and Nissl staining. The percentage of cell apoptosis and the calcium concentration were detected by Flow Cytometry in vitro. The amount of synaptic protein and related proteins in the Fyn/GluN2B/CaMKIIα signaling pathway were detected by Western Blot. KEY FINDINGS: In the present article, Panaxadiol could significantly improve the ability of learning and memory of mice and reduce its synaptic dysfunction. Panaxadiol could down-regulate GluN2B's phosphorylation level by inhibition Fyn kinase activity, Subsequently, decrease Ca2+-mediated synaptic damage, reducing LDH leakage, inhibiting apoptosis in AD, resulting in facilitating the cells survival. For the underlying molecular mechanism, we used PP2 to block the Fyn/GluN2B/CaMKIIα signaling pathway. The results from WB showed that the expression of related proteins in the Fyn signaling pathway decreased with PP2 treated. SIGNIFICANCE: Our results indicate that Panaxadiol could decrease synaptic damage, which will cause AD via inhibition of the Fyn/GluN2B/CaMKIIα signaling pathway. Thus, the Panaxadiol is a best promising candidate to test as a potential therapy for AD.

Osthole decreases tau protein phosphorylation via PI3K/AKT/GSK-3ß signaling pathway in Alzheimer's disease.

AIM: Alzheimer's disease (AD), a neurodegenerative disease, was characterized by the loss of memory and progressive cognitive deterioration. Up to now, there has no effective drugs to cure or delay the state of illness. Increasing evidence indicates that hyperphosphorylated tau protein plays a pivotal role in the occurrence and development of AD. Therefore, in present study, we aim to investigate whether osthole (OST) could decrease hyperphosphorylated tau protein in AD and the underlying mechanism. MAIN METHODS: The ability of learning and memory was detected by Morris Water Maze. The pathological changes were detected by H&E staining. The percentage of cells apoptosis was detected by TUNEL assay in vivo and Flow Cytometry in intro. The expressions of tau protein and related proteins in PI3K/Akt/GSK-3ß signaling pathway were detected by Western Blot. KEY FINDINGS: We found that OST could significantly improve learning and memory dysfunction, ameliorate the histology structure of damaged neural cells in hippocampal area. Moreover, we also found that OST could decrease tau protein phosphorylation as well as inhibit cells apoptosis. To explore the underlying mechanism, we used LY294002 to block PI3K/Akt/GSK-3ß signaling pathway, the results from Western bolt showed that the expression of related proteins in PI3K signaling pathway were decreased with LY294002 treated. SIGNIFICANCE: Taken together, the results indicated that OST could decrease phosphorylated tau levels via activation of PI3K/Akt/GSK-3ß signaling pathway. Thus, this study demonstrated that OST might be a potential candidate for the treatment of AD.

Osthole Delays Tert-Butyl Hydroperoxide-Induced Premature Senescence in Neural Stem Cells.

In our previous study, we found that osthole could promote the ability of proliferation and differentiation in normal neural stem cells (NSCs) under normal condition. Then, we used tert-butyl hydroperoxide (t-BHP) to establish the model of senescence NSCs to detect the effects of osthole. Interestingly, the immunofluorescence results showed that osthole (100 µM) could enhance the ability of proliferation and differentiation, and CCK-8 assay results showed that osthole could also enhance the cell viabilities. Then, SA-ß-gal assay results showed that osthole could decrease the positive of senescence cells. Flow cytometric analysis results showed that osthole could decrease the mixture of G0 and G1 phase. Reverse transcriptase (RT)-polymerase chain reaction results showed that osthole could downregulate the expression of p16 mRNA, and western blot analysis results showed that the expressions of the target protein decreased in p16-pRb signaling pathway with osthole treatment. In conclusion, these results indicated that osthole could probably delay cells senescence through p16-pRb signaling pathway.

Proscillaridin A induces apoptosis and suppresses non-small-cell lung cancer tumor growth via calcium-induced DR4 upregulation.

Non-small-cell lung cancer (NSCLC) is the predominant histological type of lung cancer and is characterized by the highest mortality and incidence rates among these types of malignancies. Cardiac glycosides, a class of natural products, have been identified as a potential type of chemotherapeutic agent. This study aims to investigate the anti-cancer effects and the mechanisms of action of Proscillaridin A (P.A) in NSCLC cells. In vitro sodium-potassium pump (Na+/K+ ATPase) enzyme assays indicated that P.A is a direct Na+/K+ ATPase inhibitor. P.A showed potent cytotoxic effects in NSCLC cells at nanomolar levels. Treatment mechanism studies indicated that P.A elevated Ca2+ levels, activated the AMPK pathway and downregulated phosphorylation of ACC and mTOR. Subsequently, P.A increased death receptor 4 (DR4) expression and downregulated NF-κB. Interestingly, P.A selectively suppressed EGFR activation in EGFR mutant cells but not in EGFR wild-type cells. In vivo, P.A significantly suppressed tumor growth in nude mice compared to vehicle-treated mice. Compared with the Afatinib treatment group, P.A displayed less pharmaceutical toxicity, as the body weight of mice treated with P.A did not decrease as much as those treated with Afatinib. Consistent changes in protein levels were obtained from western blotting analysis of tumors and cell lines. Immunohistochemistry analysis of the tumors from P.A-treated mice showed a significant suppression of EGFR phosphorylation (Tyr 1173) and reduction of the cell proliferation marker Ki-67. Taken together, our results suggest that P.A is a promising anti-cancer therapeutic candidate for NSCLC.

Osthole promotes endogenous neural stem cell proliferation and improved neurological function through Notch signaling pathway in mice acute mechanical brain injury.

Mechanical brain injury (MBI) is a common neurotrosis disorder of the central nervous system (CNS), which has a higher mortality and disability. In the case of MBI, neurons death leads to loss of nerve function. To date, there was no satisfactory way to restore neural deficits caused by MBI. Endogenous neural stem cells (NSCs) can proliferate, differentiate and migrate to the lesions after brain injury, to replace and repair the damaged neural cells in the subventricular zone (SVZ), hippocampus and the regions of brain injury. In the present study, we first prepared a mouse model of cortical stab wound brain injury. Using the immunohistochemical and hematoxylin-eosin (H&E) staining method, we demonstrated that osthole (Ost), a natural coumarin derivative, was capable of promoting the proliferation of endogenous NSCs and improving neuronal restoration. Then, using the Morris water maze (MWM) test, we revealed that Ost significantly improved the learning and memory function in the MBI mice, increased the number of neurons in the regions of brain injury, hippocampus DG and CA3 regions. Additionally, we found that Ost up-regulated the expression of self-renewal genes Notch 1 and Hes 1. However, when Notch activity was blocked by the γ-secretase inhibitor DAPT, the expression of Notch 1 and Hes 1 mRNA was down-regulated, augmentation of NICD and Hes 1 protein was ameliorated, the proliferation-inducing effect of Ost was abolished. These results suggested that the effects of Ost were at least in part mediated by activation of Notch signaling pathway. Our findings support that Ost is a potential drug for treating MBI due to its neuronal restoration.

[Osthole suppresses amyloid precursor protein expression by up-regulating miRNA-101a-3p in Alzheimer's disease cell model].

OBJECTIVE: To investigate the effect of osthole on the expression of amyloid precursor protein (APP) in Alzheimer's disease (AD) cell model and its mechanism. METHODS: The SH-SY5Y cell with over expression of APP was established by transfection by liposome 2000. The cells were treated with different concentrations of osthole, and the cell viability was determined by MTT and lactate dehydrogenase (LDH) assay. The differentially expressed miRNAs with and without osthole treatment were detected by miRNA array, and the target genes binding to the differentially expressed miRNAs were identified and verified by databases and Cytoscape. After the inhibitor of the differentially expressed miRNA was transduced into cells, the changes of APP and amyloid ß (Aß) protein were determined by immunofluorescence cytochemistry, and the mRNA expression of APP was determined by RT-PCR. RESULTS: The AD cell model with over expression of APP was established successfully. The results of MTT and LDH assay showed that osthole had a protective effect on cells and alleviated cell damage. miR-101a-3p was identified as the differentially expressed miRNA, which was binding to the 3'-UTR of APP. Compared with APP group, the expression of APP and Aß protein and APP mRNA increased in the miR-101a-3p inhibitor group (all P<0.01), while the expression of APP and Aß protein and APP mRNA decreased in the cells with osthole treatment (all P<0.01). CONCLUSIONS: Osthole inhibits the expression of APP by up-regulating miR-101a-3p in AD cell model.

Identification of a cyclodextrin inclusion complex of antimicrobial peptide CM4 and its antimicrobial activity.

Antibacterial peptide CM4 (ABP-CM4) is a natural product isolated from the silkworm Bombyx mori. It is a small cationic peptide with broad-spectrum activities against harmful microorganisms and may be used as a novel food preservative. However, ABP-CM4 lacks tertiary structure in water-like solutions, which makes it more susceptible to proteases and labile when exposed to air. In this study, ß-cyclodextrin (ß-CD) was chosen to form an inclusion complex with ABP-CM4, which enhanced the physical and chemical properties of ABP-CM4 but did not decrease its antibacterial activity. The storage stability and susceptibility to proteinases of ABP-CM4 were apparently improved under the protection of ß-CD. This technology could also be widely applied to other AMPs as an antimicrobial system to be used in the food industry.