SKP2 attenuates autophagy through Beclin1-ubiquitination and its inhibition reduces MERS-Coronavirus infection

A depression-associated protein FKBP5 functions in autophagy initiation through scaffolding the VPS34 complex

Common variants in the FKBP5 gene have been implicated in recurrence of major depressive disorder (MDD) and response to antidepressant treatment. Although the relationship between FKBP5 and MDD has been revealed through several studies, the detailed molecular mechanisms by which FKBP5 regulates responsiveness to antidepressants have not been fully understood. Here, we aimed to elucidate the molecular mechanisms of FKBP5 in autophagy initiation and its potential role in the antidepressant response. We found that FKBP5 deficiency impaired the initiation of basal and stress-induced autophagy, accompanied by reduced protein levels of the PIK3C3/VPS34 complex, which is essential for autophagy initiation. Mechanistically, we demonstrated that FKBP5 physically binds to the VPS34 complex components, facilitating their assembly and subsequent autophagy initiation. Particularly, our study revealed that FKBP5 mediates antidepressant-induced autophagy by promoting the VPS34 complex assembly. These findings were consistent in neuronal cells, where FKBP5 depletion resulted in decreased autophagy and impaired the VPS34 complex assembly. Understanding the interplay between FKBP5, autophagy, and MDD may provide new insights into more effective treatments for MDD and related disorders.

RNF144A inhibits autophagy by targeting BECN1 for degradation during L. monocytogenes infection

Listeria monocytogenes (L. monocytogenes, Lm) is widely used in the laboratory as an infection model for the research on pathogenesis and host defense against gram-positive intracellular bacteria. Macroautophagy (called simply "autophagy" hereafter), is important in the host defense against pathogens, such as bacteria, viruses, and parasites. BECN1 plays a pivotal role in the initiation of autophagy and accumulating evidence indicates that post-translational modifications of BECN1 provide multiple strategies for autophagy regulation. In this study, we demonstrated that the RING1-IBR-RING2 (RBR) family member RNF144A (ring finger protein 144A), which was induced by Lm infection, promoted Lm infection in an autophagy-dependent but STING1-independent pattern. rnf144a deficiency in mice protected mice from Lm infection with inhibited innate immune responses. Interestingly, RNF144A decreased Lm-induced autophagosome accumulation. Mechanistic investigation indicated that RNF144A interacted with BECN1 and promoted its K48-linked ubiquitination, leading to the subsequent proteasome-dependent degradation of BECN1 and reduced autophagosome accumulation. Further study demonstrated that RNF144A promoted the ubiquitination of BECN1 at K117 and K427, and these two ubiquitination sites were essential to the role of BECN1 in autophagy and Lm infection. Thus, our findings suggested a new regulator in intracellular bacterial infection and autophagy, which may contribute to our understanding of host defense against intracellular bacterial infection via autophagy.Abbreviations: ATG3: autophagy related 3; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG10: autophagy related 10; ATG12: autophagy related 12; ATG16L1: autophagy related 16 like 1; Baf A1: bafilomycin A1; BECN1: beclin 1; BMDC: bone marrow-derived dendritic cell; BMDM: bone marrow-derived macrophage; CFUs: colony-forming units; CHX: cycloheximide; CQ: chloroquine; CXCL10/IP-10: C-X-C motif chemokine ligand 10; EBSS: Earle's balanced salt solution; ELISA: enzyme-linked immunosorbent assay; IFIT1/ISG56: interferon induced protein with tetratricopeptide repeats 1; IFNB/IFN-β: interferon beta; IL6: interleukin 6; IRF3, interferon regulatory factor 3; Lm: L. monocytogenes; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; MOI: multiplicity of infection; PLA: proximity ligation assay; PMA: phorbol myristate acetate; PMA-THP1, PMA-differentiated THP1; PMs: peritoneal macrophages; PTMs: posttranslational modifications; RBR: RING1-IBR-RING2; RNF144A: ring finger protein 144A; STING1, stimulator of interferon response cGAMP interactor 1; TBK1, TANK binding kinase 1; TNF/TNF-α: tumor necrosis factor.

Modulatory Effects of the Recombinant Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Spike S1 Subunit Protein on the Phenotype of Camel Monocyte-Derived Macrophages

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an emerging zoonotic pathogen with different pathogenesis in humans and camels. The mechanisms behind the higher tolerance of camels to MERS-CoV infection are still unknown. Monocytes are innate myeloid cells that are able, depending on the local stimulation in their microenvironment, to differentiate into different functional subtypes of macrophages with an impact on the adaptive immune response. Several in vitro protocols have been used to induce the differentiation of monocyte-derived macrophages (MDMs) in human and several veterinary species. Such protocols are not available for camel species. In the present study, monocytes were separated from camel blood and differentiated in vitro in the presence of different stimuli into MDM. Camel MDMs generated in the presence of a combined stimulation of monocytes with LPS and GM-CSF resulted in the development of an M1 macrophages phenotype with increased abundance of the antigen-presentation receptor MHCII molecules and a decreased expression of the scavenger receptor CD163. The expression pattern of the cell markers CD163, CD14, CD172a, CD44, and CD9 on MDM generated in the presence of the MERS-CoV S1 protein revealed similarity with M-CSF-induced MDM, suggesting the potential of the MERS-CoV S1 protein to induce an M2 macrophages phenotype. Similarly to the effect of M-CSF, MERS-CoV-S protein-induced MDMs showed enhanced phagocytosis activity compared to non-polarized or LPS/GM-CSF-polarized MDMs. Collectively, our study represents the first report on the in vitro generation of monocyte-derived macrophages (MDMs) in camels and the characterization of some phenotypic and functional properties of camel MDM under the effect of M1 and M2 polarizing stimuli. In addition, the results suggest a polarizing effect of the MERS-CoV S1 protein on camel MDMs, developing an M2-like phenotype with enhanced phagocytosis activity. To understand the clinical relevance of these in vitro findings on disease pathogenesis and camel immune response toward MERS-CoV infection, further studies are required.

Autophagy and Respiratory Viruses: Mechanisms, Viral Exploitation, and Therapeutic Insights

Respiratory viruses, such as influenza virus, rhinovirus, coronavirus, and respiratory syncytial virus (RSV), continue to impose a heavy global health burden. Despite existing vaccination programs, these infections remain leading causes of morbidity and mortality, especially among vulnerable populations like children, older adults, and immunocompromised individuals. However, the current therapeutic options for respiratory viral infections are often limited to supportive care, underscoring the need for novel treatment strategies. Autophagy, particularly macroautophagy, has emerged as a fundamental cellular process in the host response to respiratory viral infections. This process not only supports cellular homeostasis by degrading damaged organelles and pathogens but also enables xenophagy, which selectively targets viral particles for degradation and enhances cellular defense. However, viruses have evolved mechanisms to manipulate the autophagy pathways, using them to evade immune detection and promote viral replication. This review examines the dual role of autophagy in viral manipulation and host defense, focusing on the complex interplay between respiratory viruses and autophagy-related pathways. By elucidating these mechanisms, we aim to highlight the therapeutic potential of targeting autophagy to enhance antiviral responses, offering promising directions for the development of effective treatments against respiratory viral infections.

Clinical safety and pharmacokinetics of a novel oral niclosamide formulation compared with marketed niclosamide chewing tablets in healthy volunteers: A three-part randomized, double-blind, placebo-controlled trial

AIM

Niclosamide is an established anthelmintic substance and a promising candidate for treating cancer, viral infections, and other diseases. However, its solubility in aqueous media is low, and the systemic bioavailability of the commercially available chewing tablet is poor, limiting the use of niclosamide for systemic treatment. A liquid oral formulation using polyethylene glycol 400 was developed and investigated in healthy volunteers to assess safety, tolerability, and pharmacokinetics in comparison to the marketed tablet. (ClinicalTrials.gov: NCT04644705).

METHODS

The study consisted of three parts: Part A was a double-blind placebo-controlled single ascending dose trial in three dose groups (200, 600, and 1600 mg) with four participants receiving either the investigational niclosamide formulation or placebo (3:1) under fasted and/or fed conditions. Part B was a crossover study comparing 1600 mg investigational niclosamide solution with the marketed 2000 mg chewing tablet in four healthy volunteers. Part C was a double-blind placebo-controlled multiple-dose trial comparing 1200 mg and 1600 mg (verum: placebo 4:2) in two dose groups with six subjects each, who received daily doses for seven days.

RESULTS

No serious or severe adverse events occurred. The most frequent adverse events were mild to moderate gastrointestinal reactions. There was also no apparent dependence between drug exposure levels (AUC, Cmax) and the severity and incidence of adverse events detectable. A relevant food effect was observed with a mean AUClast about 2-fold higher in fed condition compared to fasted condition. In Part B, dose-normalized Cmax and AUClast were similar for niclosamide solution and tablet. Absorption of niclosamide solution was highly variable. Some individuals showed high absorption (Cmax > 2µg/ml) whereas others did absorb only marginally. Importantly, there was no dose linearity in the range of 200 mg - 1600 mg. No signs of relevant systemic drug accumulation after multiple administrations were observed.

CONCLUSION

Overall safety and tolerability observed in healthy subjects were benign. This is also true for individuals with high absorption (Cmax > 2µg/ml), encouraging further research into niclosamide as a potential therapeutic agent. Galenic optimization, however, will remain challenging as evident from the observed exposure variability and non-linear PK. Non-linearity, if confirmed by additional data, might make niclosamide more suitable for multi-dose rather than high single dose regimens. The observed food effect should also be considered when further investigating systemic niclosamide exposures.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04644705.

Mechanism of histone demethylase KDM5A in osteoporotic fracture healing through epigenetic regulation of the miR-495/SKP2/Runx2 axis

BACKGROUND

Osteoporosis represents a salient metabolic bone disorder. Histone demethylase plays a vital role in bone development and homeostasis. This study explored the mechanism of histone demethylase KDM5A affecting osteoporotic fracture healing via the miR-495/SKP2/Runx2 axis.

METHODS

The murine model of osteoporotic fracture was established. The bone mineral density, maximum elastic stress, and maximum load were tested. The relative trabecular bone volume, bone trabecular thickness, and trabecular number at the proximal end of tibia were detected. The histopathological changes of femur tissues and bone microstructure were observed. Expressions of KDM5A and osteogenic factors were detected. The cell proliferation, alkaline phosphatase activity, and calcified nodules were measured. The binding relationships between KDM5A and miR-495 promoter, and miR-495 and SKP2 were verified. The interaction between SKP2 and Runx2 was detected. The ubiquitination level of Runx2 and the stability of Runx2 protein were detected.

RESULTS

KDM5A was highly expressed in the murine model of osteoporotic fracture. Interference of KDM5A expression facilitated fracture healing in osteoporotic mice. KDM5A downregulated miR-495 expression by promoting the H3K4me3 methylation of the miR-495 promoter. Inhibition of miR-495 reversed the effect of KDM5A silencing on osteoblast proliferation, differentiation, and mineralization. miR-495 facilitated osteoblast proliferation, differentiation, and mineralization by targeting SKP2. SKP2 suppressed Runx2 expression through ubiquitination degradation. Inhibition of Runx2 reversed the promoting effect of SKP2 silencing on osteogenic differentiation.

CONCLUSION

KDM5A attenuated the inhibition of miR-495 on SKP2 and promoted the ubiquitination degradation of Runx2 protein by SKP2, thereby repressing osteoblast differentiation and retarding osteoporotic fracture healing.

Prophylaxis for renal patients at risk of COVID-19 infection: results from the intranasal niclosamide randomised, double blinded, placebo controlled arm of the PROTECT-V platform trial

PURPOSE

Despite vaccination, many patients remain vulnerable to COVID-19 infection and poorer outcomes, because of underlying health conditions resulting in sub-optimal vaccine responses. This study aims to demonstrate whether intranasal niclosamide confers additional protection against COVID-19 infection above standard preventative measures including vaccination.

METHODS

PROTECT-V (PROphylaxis for paTiEnts at risk of COVID-19 infecTion) is a platform trial testing multiple pre-exposure COVID-19 prophylactic agents in vulnerable patients. This paper reports results from the randomised, double blind, placebo controlled intranasal niclosamide arm. 1651 adult patients on dialysis, with a kidney transplant or renal autoimmune conditions on immunosuppression were randomised from 48 sites (37 UK; 11 Indian). Intranasal niclosamide or matched placebo was administered twice daily, for up to nine months. Primary outcome was time to symptomatic COVID-19 infection.

RESULTS

1651 patients were randomised (826 niclosamide;825 placebo) between February 2021 to November 2022. 655(39.7%) were dialysis patients, 622(37.7%) kidney transplant recipients and 374(22.7%) had renal autoimmune disease. 97.5% patients in the UK and 66.4% patients in India with comparable proportions in both treatment groups had received COVID-19 vaccinations. Despite no adverse safety signal, there was a high withdrawal rate (40% niclosamide;23.8% placebo) due to local upper airway irritation leading to a significantly shorter treatment duration in the niclosamide group). Symptomatic COVID-19 infection during study treatment was observed in 103 patients in the niclosamide group and 133 in the placebo group (estimated hazard ratio 1.02(95%CI 0.79-1.32)).

CONCLUSION

Intranasal niclosamide did not reduce risk of symptomatic COVID-19 infection in this cohort compared to placebo.

TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov: NCT04870333 (submitted 01/03/2021; posted 03/05/2021), EudraCT: 2020-004144-28 and the Clinical Trials Registry of India (CTRI):#CTRI/2022/03/040802.

The Interplay Between Viral Infection and Cell Death: A Ping-Pong Effect

Programmed cell death (PCD) is a well-studied cellular mechanism that plays a critical role in immune responses, developmental processes, and the maintenance of tissue homeostasis. However, viruses have developed diverse strategies to bypass or manipulate the host apoptotic machinery to enhance their replication and survival. As a result, the interaction between PCD pathways and viruses has garnered increased interest, leading to many studies being published in recent years. This study aims to provide an overview of the current understanding of PCD pathways and their significance in viral infections. We will discuss various forms of cell death pathways, including apoptosis, autophagy, necroptosis, and pyroptosis, as well as their corresponding molecular mechanisms. In addition, we will show how viruses manipulate host PCD pathways to prevent or delay cell death or facilitate viral replication. This study emphasizes the importance of investigating the mechanisms by which viruses control the host's PCD machinery to gain insight into the evolutionary dynamics of host-pathogen interactions and to develop new approaches for predicting and managing viral threats. Overall, we aimed to highlight new research areas in PCD and viruses, including introduction of new targets for the development of new antiviral drugs to modulate the cellular apoptotic machinery and novel inhibitors of host cell death pathways.

MLKL-USP7-UBA52 signaling is indispensable for autophagy in brain through maintaining ubiquitin homeostasis

Individuals with genetic elimination of MLKL (mixed lineage kinase domain like pseudokinase) exhibit an increased susceptibility to neurodegenerative diseases like Alzheimer disease (AD). However, the mechanism is not yet fully understood. Here, we observed significant compromise in macroautophagy/autophagy in the brains of mlkl knockout (KO) mice, as evidenced by the downregulation of BECN1/Beclin1 and ULK1 (unc-51 like autophagy activating kinase 1). We identified UBA52 (ubiquitin A-52 residue ribosomal protein fusion product 1) as the binding partner of MLKL under physiological conditions. Loss of Mlkl induced a decrease in ubiquitin levels by preventing UBA52 cleavage. Furthermore, we demonstrated that the deubiquitinase (DUB) USP7 (ubiquitin specific peptidase 7) mediates the processing of UBA52, which is regulated by MLKL. Moreover, our results indicated that the reduction of BECN1 and ULK1 upon Mlkl loss is attributed to a decrease in their lysine 63 (K63)-linked polyubiquitination. Additionally, single-nucleus RNA sequencing revealed that the loss of Mlkl resulted in the disruption of multiple neurodegenerative disease-related pathways, including those associated with AD. These results were consistent with the observation of cognitive impairment in mlkl KO mice and exacerbation of AD pathologies in an AD mouse model with mlkl deletion. Taken together, our findings demonstrate that MLKL-USP7-UBA52 signaling is required for autophagy in brain through maintaining ubiquitin homeostasis, and highlight the contribution of Mlkl loss-induced ubiquitin deficits to the development of neurodegeneration. Thus, the maintenance of adequate levels of ubiquitin may provide a novel perspective to protect individuals from multiple neurodegenerative diseases through regulating autophagy.Abbreviations: 4HB: four-helix bundle; AAV: adeno-associated virus; AD: Alzheimer disease; AIF1: allograft inflammatory factor 1; APOE: apolipoprotein E; APP: amyloid beta precursor protein; Aβ: amyloid β; BECN1: beclin 1; co-IP: co-immunoprecipitation; DEGs: differentially expressed genes; DLG4: discs large MAGUK scaffold protein 4; DUB: deubiquitinase; EBSS: Earle's balanced salt solution; GFAP: glial fibrillary acidic protein; HRP: horseradish peroxidase; IL1B: interleukin 1 beta; IL6: interleukin 6; IPed: immunoprecipitated; KEGG: Kyoto Encyclopedia of Genes and Genomes; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MLKL: mixed lineage kinase domain like pseudokinase; NSA: necrosulfonamide; OPCs: oligodendrocyte precursor cells; PFA: paraformaldehyde; PsKD: pseudo-kinase domain; SYP: synaptophysin; UB: ubiquitin; UBA52: ubiquitin A-52 residue ribosomal protein fusion product 1; UCHL3: ubiquitin C-terminal hydrolase L3; ULK1: unc-51 like autophagy activating kinase 1; UMAP: uniform manifold approximation and projection; UPS: ubiquitin-proteasome system; USP7: ubiquitin specific peptidase 7; USP9X: ubiquitin specific peptidase 9 X-linked.

Targeting SIRT1 by Scopoletin to Inhibit XBB.1.5 COVID-19 Life Cycle

Natural products have historically driven pharmaceutical discovery, but their reliance has diminished with synthetic drugs. Approximately 35% of medicines originate from natural products. Scopoletin, a natural coumarin compound found in herbs, exhibits antioxidant, hepatoprotective, antiviral, and antimicrobial properties through diverse intracellular signaling mechanisms. Furthermore, it also enhances the activity of antioxidants. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes viral pneumonia through cytokine storms and systemic inflammation. Cellular autophagy pathways play a role in coronavirus replication and inflammation. The Silent Information Regulator 1 (SIRT1) pathway, linked to autophagy, protects cells via FOXO3, inhibits apoptosis, and modulates SIRT1 in type-II epithelial cells. SIRT1 activation by adenosine monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) enhances the autophagy cascade. This pathway holds therapeutic potential for alveolar and pulmonary diseases and is crucial in lung inflammation. Angiotensin-converting enzyme 2 (ACE-2) activation, inhibited by reduced expression, prevents COVID-19 virus entry into type-II epithelial cells. The coronavirus disease 2019 (COVID-19) virus binds ACE-2 to enter into the host cells, and XBB.1.5 COVID-19 displays high ACE-2-binding affinity. ACE-2 expression in pneumocytes is regulated by signal transducers and activators of transcription-3 (STAT3), which can increase COVID-19 virus replication. SIRT1 regulates STAT3, and the SIRT1/STAT3 pathway is involved in lung diseases. Therapeutic regulation of SIRT1 protects the lungs from inflammation caused by viral-mediated oxidative stress. Scopoletin, as a modulator of the SIRT1 cascade, can regulate autophagy and inhibit the entry and life cycle of XBB.1.5 COVID-19 in host cells.

Castration-resistant prostate cancer is resensitized to androgen deprivation by autophagy-dependent apoptosis induced by blocking SKP2

Resistance to androgen receptor (AR)-targeted therapies for prostate cancer (PCa) is characteristic of an aggressive subtype called castration-resistant prostate cancer (CRPC) and is often associated with tumor relapse. Both relapse and poor prognosis in patients with CRPC are associated with increased abundance of the E3 ubiquitin ligase SKP2. Therefore, we investigated the therapeutic potential of combined inhibition of AR and SKP2 for CRPC. We found that combined targeting of AR and SKP2 with small-molecule inhibitors decreased proliferation in two CRPC cell lines in culture and in xenografts in humanized mice. Furthermore, combined therapy in mice markedly decreased the growth of Pten/Trp53 double-knockout tumors, a particularly invasive model of CRPC, whereas disruption of either AR or SKP2 alone only modestly suppressed their growth. Mechanistically, the inhibition of SKP2 in CRPC cells induced autophagy-dependent apoptosis and promoted luminal-associated phenotypes, which promoted responsiveness to AR-targeted therapy. These effects were further enhanced by coinhibition of AR and were not induced by the AR inhibitor alone. Our findings indicate that targeting both AR and SKP2 signaling pathways is necessary to treat CRPC.

Ginkgo biloba extract alleviates deltamethrin-induced testicular injury by upregulating SKP2 and inhibiting Beclin1-independent autophagy

BACKGROUND

Male infertility is a worldwide concern that is associated with a decline in sperm quality. Environmental pollutants such as deltamethrin (DM) have harmful effects on male reproductive organs. By maintaining intracellular redox homeostasis, ginkgo biloba extract (GBE) can alleviate male reproductive dysfunction. However, research on the mechanisms by which GBE alleviates reproductive toxicity induced by DM is limited.

PURPOSE

In this study, we investigated whether GBE can alleviate DM-induced testicular and Sertoli cell reproductive toxicity by modulating SKP2 and Beclin1, thus providing a theoretical basis for the development of novel therapeutic approaches.

STUDY DESIGN

We explored the role of GBE in mitigating DM-induced testicular damage, with a specific focus on the intricate involvement of ubiquitination and autophagy.

METHODS

An experimental model was constructed using ICR male mice and the TM4 cell line. Tissue, cellular, and sperm morphological changes were observed through methods such as Hematoxylin and Eosin (H&E) staining, Periodate-Schiff (PAS) staining, ultrastructural observation, immunohistochemistry, and immunofluorescence. Enzyme and hormone levels were measured, and gene and protein levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting techniques.

RESULTS

In vivo experiments showed that DM exposure led to decreased sex hormone levels, increased seminiferous tubule diameter and impaired spermatogenesis. Meanwhile, DM exposure was found to decrease ubiquitination levels, leading to mitochondrial damage and further escalation of mitochondrial autophagy. Furthermore, in the DM-induced cell model, the upregulation of Beclin1 expression was associated with the inhibition of the ubiquitin‒proteasome system (UPS) and SKP2, thereby exacerbating autophagy. However, GBE has demonstrated notable efficacy in alleviating the reproductive toxicity induced by DM.

CONCLUSION

Our findings highlighted that SKP2 is a key regulator of Beclin1-independent autophagy and that GBE exerts therapeutic effects by upregulating SKP2 and inhibiting Beclin1 activation, which ameliorates autophagy and reduces DM-induced testicular damage.

Interaction between coronaviruses and the autophagic response

In recent years, the emergence and widespread dissemination of the coronavirus SARS-CoV-2 has posed a significant threat to global public health and social development. In order to safely and effectively prevent and control the spread of coronavirus diseases, a profound understanding of virus-host interactions is paramount. Cellular autophagy, a process that safeguards cells by maintaining cellular homeostasis under diverse stress conditions. Xenophagy, specifically, can selectively degrade intracellular pathogens, such as bacteria, fungi, viruses, and parasites, thus establishing a robust defense mechanism against such intruders. Coronaviruses have the ability to induce autophagy, and they manipulate this pathway to ensure their efficient replication. While progress has been made in elucidating the intricate relationship between coronaviruses and autophagy, a comprehensive summary of how autophagy either benefits or hinders viral replication remains elusive. In this review, we delve into the mechanisms that govern how different coronaviruses regulate autophagy. We also provide an in-depth analysis of virus-host interactions, particularly focusing on the latest data pertaining to SARS-CoV-2. Our aim is to lay a theoretical foundation for the development of novel coronavirus vaccines and the screening of potential drug targets.

Insight into Preventing Global Dengue Spread: Nanoengineered Niclosamide for Viral Infections

Millions of cases of dengue virus (DENV) infection yearly from Aedes mosquitoes stress the need for effective antivirals. No current drug effectively combats dengue efficiently. Transient immunity and severe risks highlight the need for broad-spectrum antivirals targeting all serotypes of DENV. Niclosamide, an antiparasitic, shows promising antiviral activity against the dengue virus, but enhancing its bioavailability is challenging. To overcome this issue and enable niclosamide to address the global dengue problem, nanoengineered niclosamides can be the solution. Not only does it address cost issues but also with its broad-spectrum antiviral effects nanoengineered niclosamide offers hope in addressing the current health crisis associated with DENV and will play a crucial role in combating other arboviruses as well.

Efficacy of CP-COV03 (a niclosamide-based inorganic nanohybrid product) against severe fever with thrombocytopenia syndrome virus in an in vitro model

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease caused by the SFTS virus (SFTSV). CP-COV03 is a novel antiviral candidate that significantly enhanced the bioavailability of niclosamide through inorganic-based drug delivery technology. The active pharmaceutical ingredient of CP-COV03, niclosamide, has been previously shown to possess broad-spectrum antiviral activity against over 30 different viruses in the in vitro tests. The aim of this study is to confirm the antiviral activity of CP-COV03 against the SFTSV in an in vitro model. Vero cells and SFTS viral stock NCCP43270, a 2015 Gangwon Province isolate, were used to obtain the 50% tissue culture infective dose of the virus. Vero cells seeded in 96-well plates were infected with SFTSV for 1 h. SFTSV-infected cells were treated with CP-COV03 at various concentrations of 0.1-100 μM and incubated for 7 days. On the seventh day of the culture, the cytopathic effect (CPE) of SFTSV was checked by microscopy and the cell viability was checked by using Cell Counting Kit-8 assay. The CPE reduced as the CP-COV03 concentration increased. The 50% inhibitory concentration (IC50) range of CP-COV03 was below 0.125 µM, as determined from the viral titers of culture supernatants collected on the third day posttreatment of CP-COV03. The plaque reduction assay showed that the IC50 of CP-COV03 was 1.893 µM, as determined from the percentage reduction of plaque counts for each drug concentration on the second day posttreatment with CP-COV03. This study suggests that CP-COV03 could be used as a potential antiviral agent for SFTS.IMPORTANCEWe demonstrated a concentration-dependent response and identified low a IC50 of CP-COV03. This result is comparable to other antiviral drugs used against viruses like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We believe that our study makes a significant contribution to the literature as our findings suggest that CP-COV03 may serve as a potential treatment for SFTS, highlighting its importance in the field of antiviral research.

The role of host autophagy in intracellular protozoan parasites diseases

Intracellular protozoan parasites are the etiologic agents of important human diseases, like malaria, Chagas disease, toxoplasmosis, and leishmaniasis. Inside host cells, these parasites manipulate the host metabolism and intracellular trafficking for their own benefits and, inevitably, induce several stress response mechanisms. In this review, we discuss autophagy as a stress response mechanism that can be both (i) explored by these intracellular parasites to acquire nutrients and (ii) to restrict parasite proliferation and survival within host cells. We also discuss the immunomodulatory role of autophagy as a strategy to reduce inflammatory-mediated damage, an essential player in the pathophysiology of these parasitic diseases. At last, we propose and discuss several known autophagy modulators as possible pharmaceuticals for adjunctive therapies.

Ubiquitination regulates autophagy in cancer: simple modifications, promising targets

Autophagy is an important lysosomal degradation process that digests and recycles bio-molecules, protein or lipid aggregates, organelles, and invaded pathogens. Autophagy plays crucial roles in regulation of metabolic and oxidative stress and multiple pathological processes. In cancer, the role of autophagy is dual and paradoxical. Ubiquitination has been identified as a key regulator of autophagy that can influence various steps in the autophagic process, with autophagy-related proteins being targeted for ubiquitination, thus impacting cancer progression and the effectiveness of therapeutic interventions. This review will concentrate on mechanisms underlying autophagy, ubiquitination, and their interactions in cancer, as well as explore the use of drugs that target the ubiquitin-proteasome system (UPS) and ubiquitination process in autophagy as part of cancer therapy.

Understanding the molecular regulatory mechanisms of autophagy in lung disease pathogenesis

Lung disease development involves multiple cellular processes, including inflammation, cell death, and proliferation. Research increasingly indicates that autophagy and its regulatory proteins can influence inflammation, programmed cell death, cell proliferation, and innate immune responses. Autophagy plays a vital role in the maintenance of homeostasis and the adaptation of eukaryotic cells to stress by enabling the chelation, transport, and degradation of subcellular components, including proteins and organelles. This process is essential for sustaining cellular balance and ensuring the health of the mitochondrial population. Recent studies have begun to explore the connection between autophagy and the development of different lung diseases. This article reviews the latest findings on the molecular regulatory mechanisms of autophagy in lung diseases, with an emphasis on potential targeted therapies for autophagy.

Exploring Niclosamide as a Multi-target Drug Against SARS-CoV-2: Molecular Dynamics Simulation Studies on Host and Viral Proteins

Niclosamide has emerged as a promising repurposed drug against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In vitro studies suggested that niclosamide inhibits the host transmembrane protein 16F (hTMEM16F), crucial for lipid scramblase activity, which consequently reduces syncytia formation that aids viral spread. Based on other in vitro reports, niclosamide may also target viral proteases such as papain-like protease (PLpro) and main protease (Mpro), essential for viral replication and maturation. However, the precise interactions by which niclosamide interacts with these multiple targets remain largely unclear. Docking and molecular dynamics (MD) simulation studies were undertaken based on a homology model of the hTMEM16F and available crystal structures of SARS-CoV-2 PLpro and Mpro. Niclosamide was observed to bind stably throughout a 400 ns MD simulation at the extracellular exit gate of the hTMEM16F tunnel, forming crucial interactions with residues spanning the TM1-TM2 loop (Gln350), TM3 (Phe481), and TM5-TM6 loop (Lys573, Glu594, and Asp596). Among the SARS-CoV-2 proteases, niclosamide was found to interact effectively with conserved active site residues of PLpro (Tyr268), exhibiting better stability in comparison to the control inhibitor, GRL0617. In conclusion, our in silico analyses support niclosamide as a multi-targeted drug inhibiting viral and host proteins involved in SARS-CoV-2 infections.

Blockade of endolysosomal acidification suppresses TLR3-mediated proinflammatory signaling in airway epithelial cells

BACKGROUND

Endolysosomal compartments are acidic and contain low pH-dependent proteases, and these conditions are exploited by respiratory viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus, for escaping into the cytosol. Moreover, endolysosomes contain various pattern recognition receptors (PRRs), which respond to virus-derived pathogen-associated molecular patterns (PAMPs) by production of proinflammatory cytokines/chemokines. However, excessive proinflammatory responses can lead to a potentially lethal cytokine storm.

OBJECTIVES

Here we investigated the endosomal PRR expression profile in primary human small airway epithelial cells (HSAECs), and whether blockade of endolysosomal acidification affects their cytokine/chemokine production after challenge with virus-derived stimulants.

METHODS

HSAECs were exposed to stimulants mimicking virus-derived PAMPs, either in the absence or presence of compounds causing blockade of endolysosomal acidification, followed by measurement of cytokine expression and release.

RESULTS

We show that Toll-like receptor 3 (TLR3) is the major endosomal PRR expressed by HSAECs, and that TLR3 expression is strongly induced by TLR3 agonists, but not by a range of other PRR agonists. We also demonstrate that TLR3 engagement with its agonists elicits a robust proinflammatory cytokine/chemokine response, which is profoundly suppressed through blockade of endolysosomal acidification, by bafilomycin A1, monensin, or niclosamide. Using TLR3 reporter cells, it was confirmed that TLR3 signaling is strongly induced by Poly(I:C) and that blockade of endolysosomal acidification efficiently blocked TLR3 signaling. Finally, we show that blockade of endolysosomal acidification causes a reduction in the levels of TLR3 mRNA and protein.

CONCLUSIONS

These findings show that blockade of endolysosomal acidification suppresses TLR3-dependent cytokine and chemokine production in HSAECs.

Development of Targeted Drug Delivery System for the Treatment of SARS-CoV-2 Using Aptamer-Conjugated Gold Nanoparticles

Background: The SARS-CoV-2 pandemic has highlighted niclosamide (NIC) as a promising treatment for COVID-19. However, its clinical application is limited due to its poor water solubility, resulting in low bioavailability. Methods: To address this issue, we developed a AuNP-HA-NIC system, which combines gold nanoparticles with hyaluronic acid to enhance drug delivery. Our comprehensive characterization of the system revealed that hyaluronic acid with specific molecular weights, particularly those exposed to electron-beam irradiation between 2 and 20 kGy, produced the most stable nanoparticles for efficient drug loading and delivery. Results: Additionally, the AuNP-HA-NIC system exhibits a significant sensitivity to pH changes, which is a critical feature for targeted drug release. Under acidic conditions mimicking the stomach and small intestine, minimal drug release was observed, indicating the effective prevention of premature drug release in the gastrointestinal tract. Furthermore, the integration of a targeting aptamer established specific binding abilities towards the SARS-CoV-2 spike protein, distinguishing it from other coronaviruses. Conclusions: As research progresses, and with further in vivo testing and optimization, the AuNP-HA-NIC-aptamer system holds great promise as a game-changer in the field of antiviral therapeutics, particularly in the battle against COVID-19.

The Next Generation COVID-19 Antiviral; Niclosamide-Based Inorganic Nanohybrid System Kills SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic is a serious global threat with surging new variants of concern. Although global vaccinations have slowed the pandemic, their longevity is still unknown. Therefore, new orally administrable antiviral agents are highly demanded. Among various repurposed drugs, niclosamide (NIC) is the most potential one for various viral diseases such as COVID-19, SARS (severe acute respiratory syndrome), MERS (middle east respiratory syndrome), influenza, RSV (respiratory syncytial virus), etc. Since NIC cannot be effectively absorbed, a required plasma concentration for antiviral potency is hard to maintain, thereby restricting its entry into the infected cells. Such a 60-year-old bioavailability challenging issue has been overcome by engineering with MgO and hydroxypropyl methylcellulose (HPMC), forming hydrophilic NIC-MgO-HPMC, with improved intestinal permeability without altering NIC metabolism as confirmed by parallel artificial membrane permeability assay. The inhibitory effect on SARS-CoV-2  replication is confirmed in the Syrian hamster model to reduce lung injury. Clinical studies reveal that the bioavailability of NIC hybrid drug can go 4 times higher than the intact NIC. The phase II clinical trial shows a dose-dependent bioavailability of NIC from hybrid drug  suggesting its potential applicability as a game changer in achieving the much-anticipated endemic phase.

Targeting mitochondrial quality control: new therapeutic strategies for major diseases

Mitochondria play a crucial role in maintaining the normal physiological state of cells. Hence, ensuring mitochondrial quality control is imperative for the prevention and treatment of numerous diseases. Previous reviews on this topic have however been inconsistencies and lack of systematic organization. Therefore, this review aims to provide a comprehensive and systematic overview of mitochondrial quality control and explore the possibility of targeting the same for the treatment of major diseases. This review systematically summarizes three fundamental characteristics of mitochondrial quality control, including mitochondrial morphology and dynamics, function and metabolism, and protein expression and regulation. It also extensively examines how imbalances in mitochondrial quality are linked to major diseases, such as ischemia-hypoxia, inflammatory disorders, viral infections, metabolic dysregulations, degenerative conditions, and tumors. Additionally, the review explores innovative approaches to target mitochondrial quality control, including using small molecule drugs that regulate critical steps in maintaining mitochondrial quality, nanomolecular materials designed for precise targeting of mitochondria, and novel cellular therapies, such as vesicle therapy and mitochondrial transplantation. This review offers a novel perspective on comprehending the shared mechanisms underlying the occurrence and progression of major diseases and provides theoretical support and practical guidance for the clinical implementation of innovative therapeutic strategies that target mitochondrial quality control for treating major diseases.

Immunological and homeostatic pathways of alpha -1 antitrypsin: a new therapeutic potential

α -1 antitrypsin (A1AT) is a 52 kDa acute-phase glycoprotein belonging to the serine protease inhibitor superfamily (SERPIN). It is primarily synthesized by hepatocytes and to a lesser extent by monocytes, macrophages, intestinal epithelial cells, and bronchial epithelial cells. A1AT is encoded by SERPINA1 locus, also known as PI locus, highly polymorphic with at least 100 allelic variants described and responsible for different A1AT serum levels and function. A1AT inhibits a variety of serine proteinases, but its main target is represented by Neutrophil Elastase (NE). However, recent attention has been directed towards its immune-regulatory and homeostatic activities. A1AT exerts immune-regulatory effects on different cell types involved in innate and adaptive immunity. Additionally, it plays a role in metal and lipid metabolism, contributing to homeostasis. An adequate comprehension of these mechanisms could support the use of A1AT augmentation therapy in many disorders characterized by a chronic immune response. The aim of this review is to provide an up-to-date understanding of the molecular mechanisms and regulatory pathways responsible for immune-regulatory and homeostatic activities of A1AT. This knowledge aims to support the use of A1AT in therapeutic applications. Furthermore, the review summarizes the current state of knowledge regarding the application of A1AT in clinical and laboratory settings human and animal models.

Autophagy in Disease Onset and Progression

Autophagy is a biological phenomenon whereby components of cells can self-degrade using autophagosomes. During this process, cells can clear dysfunctional organelles or unwanted elements. Autophagy can recycle unnecessary biomolecules into new components or sometimes, even destroy the cells themselves. This cellular process was first observed in 1962 by Keith R. Porter et al. Since then, autophagy has been studied for over 60 years, and much has been learned on the topic. Nevertheless, the process is still not fully understood. It has been proven, for example, that autophagy can be a positive force for maintaining good health by removing older or damaged cells. By contrast, autophagy is also involved in the onset and progression of various conditions caused by pathogenic infections. These diseases generally involve several important organs in the human body, including the liver, kidney, heart, and central nervous system. The regulation of the defects of autophagy defects may potentially be used to treat some diseases. This review comprehensively discusses recent research frontiers and topics of interest regarding autophagy-related diseases.

NSC689857, an inhibitor of Skp2, produces antidepressant-like effects in mice

We have previously reported that two inhibitors of an E3 ligase S-phase kinase-associated protein 2 (Skp2), SMIP004 and C1, have an antidepressant-like effect in non-stressed and chronically stressed mice. This prompted us to ask whether other Skp2 inhibitors could also have an antidepressant effect. Here, we used NSC689857, another Skp2 inhibitor, to investigate this hypothesis. The results showed that administration of NSC689857 (5 mg/kg) produced an antidepressant-like effect in a time-dependent manner in non-stressed male mice, which started 8 days after drug administration. Dose-dependent analysis showed that administration of 5 and 10 mg/kg, but not 1 mg/kg, of NSC689857 produced antidepressant-like effects in both non-stressed male and female mice. Administration of NSC689857 (5 mg/kg) also induced antidepressant-like effects in non-stressed male mice when administered three times within 24 h (24, 5, and 1 h before testing) but not when administered acutely (1 h before testing). In addition, NSC689857 and fluoxetine coadministration produced additive antidepressant-like effects in non-stressed male mice. These effects of NSC689857 were not associated with the changes in locomotor activity. Administration of NSC689857 (5 mg/kg) also attenuated depression-like behaviors in male mice induced by chronic social defeat stress, suggesting therapeutic potential of NSC689857 in depression. Overall, these results suggest that NSC689857 is capable of exerting antidepressant-like effects in both non-stressed and chronically stressed mice.

Differences and similarities between innate immune evasion strategies of human coronaviruses

So far, seven coronaviruses have emerged in humans. Four recurring endemic coronaviruses cause mild respiratory symptoms. Infections with epidemic Middle East respiratory syndrome-related coronavirus or severe acute respiratory syndrome coronavirus (SARS-CoV)-1 are associated with high mortality rates. SARS-CoV-2 is the causative agent of the coronavirus disease 2019 pandemic. To establish an infection, coronaviruses evade restriction by human innate immune defenses, such as the interferon system, autophagy and the inflammasome. Here, we review similar and distinct innate immune manipulation strategies employed by the seven human coronaviruses. We further discuss the impact on pathogenesis, zoonotic emergence and adaptation. Understanding the nature of the interplay between endemic/epidemic/pandemic coronaviruses and host defenses may help to better assess the pandemic potential of emerging coronaviruses.

PIP4K2C inhibition reverses autophagic flux impairment induced by SARS-CoV-2

In search for broad-spectrum antivirals, we discovered a small molecule inhibitor, RMC-113, that potently suppresses the replication of multiple RNA viruses including SARS-CoV-2 in human lung organoids. We demonstrated selective dual inhibition of the lipid kinases PIP4K2C and PIKfyve by RMC-113 and target engagement by its clickable analog. Advanced lipidomics revealed alteration of SARS-CoV-2-induced phosphoinositide signature by RMC-113 and linked its antiviral effect with functional PIP4K2C and PIKfyve inhibition. We discovered PIP4K2C's roles in SARS-CoV-2 entry, RNA replication, and assembly/egress, validating it as a druggable antiviral target. Integrating proteomics, single-cell transcriptomics, and functional assays revealed that PIP4K2C binds SARS-CoV-2 nonstructural protein 6 and regulates virus-induced impairment of autophagic flux. Reversing this autophagic flux impairment is a mechanism of antiviral action of RMC-113. These findings reveal virus-induced autophagy regulation via PIP4K2C, an understudied kinase, and propose dual inhibition of PIP4K2C and PIKfyve as a candidate strategy to combat emerging viruses.

The relationship between autophagy and respiratory viruses

Respiratory viruses have caused severe global health problems and posed essential challenges to the medical community. In recent years, the role of autophagy as a critical process in cells in viral respiratory diseases has been noticed. One of the vital catabolic biological processes in the body is autophagy. Autophagy contributes to energy recovery by targeting and selectively directing foreign microorganisms, organelles, and senescent intracellular proteins to the lysosome for degradation and phagocytosis. Activation or suppression of autophagy is often initiated when foreign pathogenic organisms such as viruses infect cells. Because of its antiviral properties, several viruses may escape or resist this process by encoding viral proteins. Viruses can also use autophagy to enhance their replication or prolong the persistence of latent infections. Here, we provide an overview of autophagy and respiratory viruses such as coronavirus, rhinovirus, parainfluenza, influenza, adenovirus, and respiratory syncytial virus, and examine the interactions between them and the role of autophagy in the virus-host interaction process and the resulting virus replication strategy.

Revolutionizing viral disease treatment: Phase separation and lysosome/exosome targeting as new areas and new paradigms for antiviral drug research

With the advancement of globalization, our world is becoming increasingly interconnected. However, this interconnection means that once an infectious disease emerges, it can rapidly spread worldwide. Specifically, viral diseases pose a growing threat to human health. The COVID-19 pandemic has underscored the pressing need for expedited drug development to combat emerging viral diseases. Traditional drug discovery methods primarily rely on random screening and structure-based optimization, and new approaches are required to address more complex scenarios in drug discovery. Emerging antiviral strategies include phase separation and lysosome/exosome targeting. The widespread implementation of these innovative drug design strategies will contribute towards tackling existing viral infections and future outbreaks.

Plant extracts modulate cellular stress to inhibit replication of mouse Coronavirus MHV-A59

The Covid-19 infection outbreak led to a global epidemic, and although several vaccines have been developed, the appearance of mutations has allowed the virus to evade the immune response. Added to this is the existing risk of the appearance of new emerging viruses. Therefore, it is necessary to explore novel antiviral therapies. Here, we investigate the potential in vitro of plant extracts to modulate cellular stress and inhibit murine hepatitis virus (MHV)-A59 replication. L929 cells were treated with P2Et (Caesalpinia spinosa) and Anamu SC (Petiveria alliacea) plant extracts during infection and virus production, ROS (reactive oxygen species), UPR (unfolded protein response), and autophagy were assessed. P2Et inhibited virus replication and attenuated both ROS production and UPR activation induced during infection. In contrast, the sustained presence of Anamu SC during viral adsorption and replication was required to inhibit viral infection, tending to induce pro-oxidant effects, and increasing UPR gene expression. Notably, the loss of the PERK protein resulted in a slight decrease in virus yield, suggesting a potential involvement of this UPR pathway during replication. Intriguingly, both extracts either maintained or increased the calreticulin surface exposure induced during infection. In conclusion, our findings highlight the development of antiviral natural plant extracts that differentially modulate cellular stress.

Knocking out Fkbp51 decreases CCl4-induced liver injury through enhancement of mitochondrial function and Parkin activity

BACKGROUND AND AIMS

Previously, we found that FK506 binding protein 51 (Fkbp51) knockout (KO) mice resist high fat diet-induced fatty liver and alcohol-induced liver injury. The aim of this research is to identify the mechanism of Fkbp51 in liver injury.

METHODS

Carbon tetrachloride (CCl4)-induced liver injury was compared between Fkbp51 KO and wild type (WT) mice. Step-wise and in-depth analyses were applied, including liver histology, biochemistry, RNA-Seq, mitochondrial respiration, electron microscopy, and molecular assessments. The selective FKBP51 inhibitor (SAFit2) was tested as a potential treatment to ameliorate liver injury.

RESULTS

Fkbp51 knockout mice exhibited protection against liver injury, as evidenced by liver histology, reduced fibrosis-associated markers and lower serum liver enzyme levels. RNA-seq identified differentially expressed genes and involved pathways, such as fibrogenesis, inflammation, mitochondria, and oxidative metabolism pathways and predicted the interaction of FKBP51, Parkin, and HSP90. Cellular studies supported co-localization of Parkin and FKBP51 in the mitochondrial network, and Parkin was shown to be expressed higher in the liver of KO mice at baseline and after liver injury relative to WT. Further functional analysis identified that KO mice exhibited increased ATP production and enhanced mitochondrial respiration. KO mice have increased mitochondrial size, increased autophagy/mitophagy and mitochondrial-derived vesicles (MDV), and reduced reactive oxygen species (ROS) production, which supports enhancement of mitochondrial quality control (MQC). Application of SAFit2, an FKBP51 inhibitor, reduced the effects of CCl4-induced liver injury and was associated with increased Parkin, pAKT, and ATP production.

CONCLUSIONS

Downregulation of FKBP51 represents a promising therapeutic target for liver disease treatment.

CRISPRa Analysis of Phosphoinositide Phosphatases Shows That TMEM55A Is a Positive Regulator of Autophagy

Transcriptional activation, based on Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) and known as CRISPR activation (CRISPRa), is a specific and safe tool to upregulate endogenous genes. Therefore, CRISPRa is valuable not only for analysis of molecular mechanisms of cellular events, but also for treatment of various diseases. Regulating autophagy has been proposed to enhance effects of some therapies. In this study, we upregulated genes for phosphoinositide phosphatases, SACM1L, PIP4P1, and PIP4P2, using CRISPRa, and their effects on autophagy were examined. Our results suggested that TMEM55A/PIP4P2, a phosphatidylinositol-4,5-bisphosphate 4-phosphatase, positively regulates basal autophagy in 293A cells. Furthermore, it was also suggested that SAC1, a phosphatidylinositol 4-phosphatase, negatively regulates basal autophagic degradation.

Amino acid substitution L232F in non-structural protein 6 identified as a possible human-adaptive mutation in clade B MERS coronaviruses

IMPORTANCE

Viral host adaptation plays an important role in inter-species transmission of coronaviruses and influenza viruses. Multiple human-adaptive mutations have been identified in influenza viruses but not so far in MERS-CoV that circulates widely in dromedary camels in the Arabian Peninsula leading to zoonotic transmission. Here, we analyzed clade B MERS-CoV sequences and identified an amino acid substitution L232F in nsp6 that repeatedly occurs in human MERS-CoV. Using a loss-of-function reverse genetics approach, we found the nsp6 L232F conferred increased viral replication competence in vitro, in cultures of the upper human respiratory tract ex vivo, and in lungs of mice infected in vivo. Our results showed that nsp6 L232F may be an adaptive mutation associated with zoonotic transmission of MERS-CoV. This study highlighted the capacity of MERS-CoV to adapt to transmission to humans and also the need for continued surveillance of MERS-CoV in camels.

The circRNA MKLN1 regulates autophagy in the development of diabetic retinopathy

Diabetic retinopathy (DR) is a common complication in patients with diabetes and has become an important cause of blindness in working-age people. However, the mechanisms involved have not been fully elucidated. Circular RNAs (circRNAs) can play an important role in DR, and they can accurately regulate the expression of target genes through a new regulatory model: the competing endogenous RNA (ceRNA) model. We isolated total RNA from extracellular vesicles in the serum of healthy individuals (Con) and individuals with diabetes mellitus without DR (DM), nonproliferative DR (NPDR), or proliferative DR (PDR) and subjected them to deep sequencing. We found aberrantly high expression of circMKLN1. In a streptozotocin (STZ)-induced mice model of diabetes, the inhibition of circMKLN1 with AAV2 transduction markedly ameliorated retinal acellular vessels and vascular leakage, which was reversed by intravitreal injection of rapamycin, a potent autophagy inducer. In addition, circMKLN1 adsorbs miR-26a-5p as a molecular sponge and mediates high glucose (HG)/methylglyoxal (MG)-induced autophagy in hRMECs. CircMKLN1-silencing treatment reduces HG/MG-related reactive autophagy and inflammation. In addition, miR-26a-5p targeting by circMKLN1 plays an important role in the regulation of Rab11a expression. Thus, either new biomarkers or new therapeutic targets may be identified with the translation of these findings.

Lipid compartments and lipid metabolism as therapeutic targets against coronavirus

Lipids perform a series of cellular functions, establishing cell and organelles' boundaries, organizing signaling platforms, and creating compartments where specific reactions occur. Moreover, lipids store energy and act as secondary messengers whose distribution is tightly regulated. Disruption of lipid metabolism is associated with many diseases, including those caused by viruses. In this scenario, lipids can favor virus replication and are not solely used as pathogens' energy source. In contrast, cells can counteract viruses using lipids as weapons. In this review, we discuss the available data on how coronaviruses profit from cellular lipid compartments and why targeting lipid metabolism may be a powerful strategy to fight these cellular parasites. We also provide a formidable collection of data on the pharmacological approaches targeting lipid metabolism to impair and treat coronavirus infection.

Ceftazidime reduces cellular Skp2 to promote type-I interferon activity

Skp2 plays multiple roles in malignant tumours. Here, we revealed that Skp2 negatively regulates type-I interferon (IFN-I)-mediated antiviral activity. We first noticed that Skp2 can promote virus infection in cells. Further studies demonstrated that Skp2 interacts with IFN-I receptor 2 (IFNAR2) and promotes K48-linked polyubiquitination of IFNAR2, which accelerates the degradation of IFNAR2 proteins. Skp2-mediated downregulation of IFNAR2 levels inhibits IFN-I signalling and IFN-I-induced antiviral activity. In addition, we uncovered for the first time that the antibiotic ceftazidime can act as a repressor of Skp2. Ceftazidime reduces cellular Skp2 levels, thus enhancing IFNAR2 stability and IFN-I antiviral activity. This study reveals a new role of Skp2 in regulating IFN-I signalling and IFN-I antiviral activity and reports the antibiotic ceftazidime as a potential repressor of Skp2.

DHA and EPA inhibit porcine coronavirus replication by alleviating ER stress

IMPORTANCE

Porcine epidemic diarrhea caused by porcine coronaviruses remains a major threat to the global swine industry. Fatty acids are extensively involved in the whole life of the virus. In this study, we found that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) significantly reduced the viral load of porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), and porcine delta coronavirus (PDCoV) and acted on the replication of the viruses rather than attachment and entry. We further confirmed that DHA and EPA inhibited PEDV replication by alleviating the endoplasmic reticulum stress. Meanwhile, DHA and EPA alleviate PEDV-induced inflammation and reactive oxygen species (ROS) levels and enhance the cellular antioxidant capacity. These data indicate that DHA and EPA have antiviral effects on porcine coronaviruses and provide a molecular basis for the development of new fatty acid-based therapies to control porcine coronavirus infection and transmission.

M1 linear ubiquitination of LKB1 inhibits vascular endothelial cell injury in atherosclerosis through activation of AMPK

Endothelial cell injury is confirmed to be the initial step in the atherosclerosis (AS) process. Here, we tried to elucidate the role of liver kinase B1 (LKB1) and adenosine phosphate protein kinase (AMPK) in modulating vascular endothelial cells (VECs) in AS. High-fat feed (HFD)-induced AS rat models were prepared and treated with AMPK activator A-769662 alone or combined with chloroquine. An analysis of VEC injury, inflammation response, and autophagy followed it. The M1 linear ubiquitination of LKB1 was assessed by co-immunoprecipitation. The interaction between LKB1 and AMPK was analyzed. Primary aortic VECs were isolated and induced by LPS to verify the effects of LKB1 and AMPK on VEC injury in AS. Activation of AMPK reduced the VEC injury and inflammatory response of VECs and promoted autophagy caused by AS. LKB1 could regulate the activation of AMPK in AS. M1 linear ubiquitination enhanced LKB1 activity and increased AMPK activation to protect against VEC injury in AS, which was validated by in vitro experiments. Our current study highlighted that M1 linear ubiquitination of LKB1 may induce the activation of LKB1 to activate AMPK, which inhibited VEC injury in AS.

Niclosamide as a chemical probe for analyzing SARS-CoV-2 modulation of host cell lipid metabolism

Introduction

SARS-CoV-2 subverts host cell processes to facilitate rapid replication and dissemination, and this leads to pathological inflammation.

Methods

We used niclosamide (NIC), a poorly soluble anti-helminth drug identified initially for repurposed treatment of COVID-19, which activates the cells' autophagic and lipophagic processes as a chemical probe to determine if it can modulate the host cell's total lipid profile that would otherwise be either amplified or reduced during SARS-CoV-2 infection.

Results

Through parallel lipidomic and transcriptomic analyses we observed massive reorganization of lipid profiles of SARS-CoV-2 infected Vero E6 cells, especially with triglycerides, which were elevated early during virus replication, but decreased thereafter, as well as plasmalogens, which were elevated at later timepoints during virus replication, but were also elevated under normal cell growth. These findings suggested a complex interplay of lipid profile reorganization involving plasmalogen metabolism. We also observed that NIC treatment of both low and high viral loads does not affect virus entry. Instead, NIC treatment reduced the abundance of plasmalogens, diacylglycerides, and ceramides, which we found elevated during virus infection in the absence of NIC, resulting in a significant reduction in the production of infectious virions. Unexpectedly, at higher viral loads, NIC treatment also resulted in elevated triglyceride levels, and induced significant changes in phospholipid metabolism.

Discussion

We posit that future screens of approved or new partner drugs should prioritize compounds that effectively counter SARS-CoV-2 subversion of lipid metabolism, thereby reducing virus replication, egress, and the subsequent regulation of key lipid mediators of pathological inflammation.

Syringin Prevents 6-Hydroxydopamine Neurotoxicity by Mediating the MiR-34a/SIRT1/Beclin-1 Pathway and Activating Autophagy in SH-SY5Y Cells and the Caenorhabditis elegans Model

Defective autophagy is one of the cellular hallmarks of Parkinson's disease (PD). Therefore, a therapeutic strategy could be a modest enhancement of autophagic activity in dopamine (DA) neurons to deal with the clearance of damaged mitochondria and abnormal protein aggregates. Syringin (SRG) is a phenolic glycoside derived from the root of Acanthopanax senticosus. It has antioxidant, anti-apoptotic, and anti-inflammatory properties. However, whether it has a preventive effect on PD remains unclear. The present study found that SRG reversed the increase in intracellular ROS-caused apoptosis in SH-SY5Y cells induced by neurotoxin 6-OHDA exposure. Likewise, in C. elegans, degeneration of DA neurons, DA-related food-sensitive behaviors, longevity, and accumulation of α-synuclein were also improved. Studies of neuroprotective mechanisms have shown that SRG can reverse the suppressed expression of SIRT1, Beclin-1, and other autophagy markers in 6-OHDA-exposed cells. Thus, these enhanced the formation of autophagic vacuoles and autophagy activity. This protective effect can be blocked by pretreatment with wortmannin (an autophagosome formation blocker) and bafilomycin A1 (an autophagosome-lysosome fusion blocker). In addition, 6-OHDA increases the acetylation of Beclin-1, leading to its inactivation. SRG can induce the expression of SIRT1 and promote the deacetylation of Beclin-1. Finally, we found that SRG reduced the 6-OHDA-induced expression of miR-34a targeting SIRT1. The overexpression of miR-34a mimic abolishes the neuroprotective ability of SRG. In conclusion, SRG induces autophagy via partially regulating the miR-34a/SIRT1/Beclin-1 axis to prevent 6-OHDA-induced apoptosis and α-synuclein accumulation. SRG has the opportunity to be established as a candidate agent for the prevention and cure of PD.

Bidirectional interplay between SARS-CoV-2 and autophagy

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as the causative agent of the recent COVID-19 pandemic, continues representing one of the main health concerns worldwide. Autophagy, in addition to its role in cellular homeostasis and metabolism, plays an important part for the host antiviral immunity. However, viruses including SARS-CoV-2 have evolved diverse mechanisms to not only overcome autophagy's antiviral pressure but also manipulate its machinery in order to enhance viral replication and propagation. Here, we discuss our current knowledge on the impact that autophagy exerts on SARS-CoV-2 replication, as well as the different counteracting measures that this virus has developed to manipulate autophagy's complex machinery. Some of the elements regarding this interplay may become future therapeutic targets in the fight against SARS-CoV-2.

mLST8 is essential for coronavirus replication and regulates its replication through the mTORC1 pathway

Coronaviruses (CoVs), which pose a serious threat to human and animal health worldwide, need to hijack host factors to complete their replicative cycles. However, the current study of host factors involved in CoV replication remains unknown. Here, we identified a novel host factor, mammalian lethal with sec-13 protein 8 (mLST8), which is a common subunit of mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), and is critical for CoV replication. Inhibitor and knockout (KO) experiments revealed that mTORC1, but not mTORC2, is essential for transmissible gastroenteritis virus replication. Furthermore, mLST8 KO reduced the phosphorylation of unc-51-like kinase 1 (ULK1), a factor downstream of the mTORC1 signaling pathway, and mechanistic studies revealed that decreased phosphorylation of the mTORC1 downstream factor ULK1 promoted the activation of autophagy, which is responsible for antiviral replication in mLST8 KO cells. Then, transmission electron microscopy indicated that both mLST8 KO and autophagy activator inhibited the formation of double-membrane vesicles in early viral replication. Finally, mLST8 KO and autophagy activator treatment could also inhibit the replication of other CoVs, indicating a conserved relationship between autophagy activation and CoV replication. In summary, our work reveals that mLST8 is a novel host regulator of CoV replication, which provides new insights into the mechanism of CoV replication and can facilitate the development of broad-spectrum antiviral drugs. IMPORTANCE CoVs are highly variable, and existing CoV vaccines are still limited in their ability to address mutations in CoVs. Therefore, the need to improve our understanding of the interaction of CoVs with the host during viral replication and to find targets for drugs against CoVs is urgent. Here, we found that a novel host factor, mLST8, is critical for CoV infection. Further studies showed that mLST8 KO inhibited the mTORC1 signaling pathway, and we found that autophagy activation downstream of mTORC1 was the main cause of antiviral replication in mLST8 KO cells. Autophagy activation impaired the formation of DMVs and inhibited early viral replication. These findings deepen our understanding of the CoV replication process and provide insights into potential therapeutic applications.

Helicobacter pylori infection induces autophagy via ILK regulation of NOXs-ROS-Nrf2/HO-1-ROS loop

Reactive oxygen species (ROS) can regulate the occurrence of autophagy, and effective control of the balance between ROS and autophagy may be an important strategy for Helicobacter pylori induced gastric-related diseases. In this study, infection with H. pylori led to a lower level of ILK phosphorylation and increased ROS generation. Knockdown of ILK enhanced total ROS generation, and upregulated NADPH oxidase (NOX) subunit p22-phox levels. Inhibition of NOXs affected total ROS generation. The inhibition of NOX and ROS generation reduced Nrf2 and HO-1 levels, and knockdown of ILK significantly enhanced Nrf2 levels in H. pylori-infected GES-1 cells. Activation of Nrf2 by DMF decreased ROS levels. Therefore, NOX-dependent ROS production regulated by ILK was essential for activation of Nrf2/HO-1 signaling pathways in H. pylori-infected GES-1 cells. Beclin1, ATG5 and LC3B-II levels were higher both in H. pylori-infected and ILK-knockdown GES-1 cells. In NAC-pretreated GES-1 cells infected with H. pylori, the LC3B-II level was decreased compared to that in cells after H. pylori infection alone. Stable low expression of ILK with further knockdown of Beclin1 or ATG5 significantly reduced LC3B-II levels in GES-1 cells, while with the addition of the autophagy inhibitor chloroquine (CQ), LC3B-II and p62 protein levels were both remarkably upregulated. H. pylori accelerated the accumulation of ROS and further led to the induction of ROS-mediated autophagy by inhibiting ILK levels. Together, these results indicate that H. pylori infection manipulates the NOX-ROS-Nrf2/HO-1-ROS loop to control intracellular oxygen stress and further induced ROS-mediated autophagy by inhibiting ILK levels.

Microwave-assisted chemoselective synthesis and photophysical properties of 2-arylazo-biphenyl-4-carboxamides from hydrazonals

The reaction of 3-oxo-2-arylhydrazonopropanals with acetoacetanilide in an equimolar ratio, under DBU/1,4-dioxane/microwave irradiation reaction conditions, resulted in chemoselective formation of 4-arylazo-5-hydroxy-benzamide derivatives. The structures of the obtained biphenyl-4-carboxamides were characterized by several spectroscopic techniques including IR, 1H- and 13C-NMR, MS and HRMS, and X-ray single crystals of three examples. The photophysical properties of the new products were also evaluated, with a particular focus on their absorption and emission spectra, which provided valuable information regarding their optical properties. The new compounds emitted 513-549 nm green fluorescence in acetone solution under UV irradiation.

PTBP1 suppresses porcine epidemic diarrhea virus replication via inducing protein degradation and IFN production

Porcine epidemic diarrhea virus (PEDV) causes severe morbidity and mortality among newborn piglets. It significantly threatens the porcine industry in China and around the globe. To accelerate the developmental pace of drugs or vaccines against PEDV, a deeper understanding of the interaction between viral proteins and host factors is crucial. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), is crucial for controlling RNA metabolism and biological processes. The present work focused on exploring the effect of PTBP1 on PEDV replication. PTBP1 was upregulated during PEDV infection. The PEDV nucleocapsid (N) protein was degraded through the autophagic and proteasomal degradation pathways. Moreover, PTBP1 recruits MARCH8 (an E3 ubiquitin ligase) and NDP52 (a cargo receptor) for N protein catalysis and degradation through selective autophagy. Furthermore, PTBP1 induces the host innate antiviral response via upregulating the expression of MyD88, which then regulates TNF receptor-associated factor 3/ TNF receptor-associated factor 6 expression and induces the phosphorylation of TBK1 and IFN regulatory factor 3. These processes activate the type Ⅰ IFN signaling pathway to antagonize PEDV replication. Collectively, this work illustrates a new mechanism related to PTBP1-induced viral restriction, where PTBP1 degrades the viral N protein and induces type Ⅰ IFN production to suppress PEDV replication.

Repurposing Niclosamide as a Novel Anti-SARS-CoV-2 Drug by Restricting Entry Protein CD147

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the global coronavirus disease 2019 (COVID-19) pandemic, and the search for effective treatments has been limited. Furthermore, the rapid mutations of SARS-CoV-2 have posed challenges to existing vaccines and neutralizing antibodies, as they struggle to keep up with the increased viral transmissibility and immune evasion. However, there is hope in targeting the CD147-spike protein, which serves as an alternative point for the entry of SARS-CoV-2 into host cells. This protein has emerged as a promising therapeutic target for the development of drugs against COVID-19. Here, we demonstrate that the RNA-binding protein Human-antigen R (HuR) plays a crucial role in the post-transcriptional regulation of CD147 by directly binding to its 3'-untranslated region (UTR). We observed a decrease in CD147 levels across multiple cell lines upon HuR depletion. Furthermore, we identified that niclosamide can reduce CD147 by lowering the cytoplasmic translocation of HuR and reducing CD147 glycosylation. Moreover, our investigation revealed that SARS-CoV-2 infection induces an upregulation of CD147 in ACE2-expressing A549 cells, which can be effectively neutralized by niclosamide in a dose-dependent manner. Overall, our study unveils a novel regulatory mechanism of regulating CD147 through HuR and suggests niclosamide as a promising therapeutic option against COVID-19.

Therapeutic potential of salicylamide derivatives for combating viral infections

Since time immemorial human beings have constantly been fighting against viral infections. The ongoing and devastating coronavirus disease 2019 pandemic represents one of the most severe and most significant public health emergencies in human history, highlighting an urgent need to develop broad-spectrum antiviral agents. Salicylamide (2-hydroxybenzamide) derivatives, represented by niclosamide and nitazoxanide, inhibit the replication of a broad range of RNA and DNA viruses such as flavivirus, influenza A virus, and coronavirus. Moreover, nitazoxanide was effective in clinical trials against different viral infections including diarrhea caused by rotavirus and norovirus, uncomplicated influenza A and B, hepatitis B, and hepatitis C. In this review, we summarize the broad antiviral activities of salicylamide derivatives, the clinical progress, and the potential targets or mechanisms against different viral infections and highlight their therapeutic potential in combating the circulating and emerging viral infections in the future.

SKP2 Contributes to AKT Activation by Ubiquitination Degradation of PHLPP1, Impedes Autophagy, and Facilitates the Survival of Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common subtype of thyroid carcinoma. Despite a good prognosis, approximately a quarter of PTC patients are likely to relapse. Previous reports suggest an association between S-phase kinase-associated protein 2 (SKP2) and the prognosis of thyroid cancer. SKP1 is related to apoptosis of PTC cells; however, its role in PTC remains largely elusive. This study aimed to understand the expression and molecular mechanism of SKP2 in PTC. SKP2 expression was upregulated in PTC tissues and closely associated with clinical diagnosis. In vitro and in vivo knockdown of SKP2 expression in PTC cells suppressed cell growth and proliferation and induced apoptosis. SKP2 depletion promoted cell autophagy under glucose deprivation. SKP2 interacted with PH domain leucine-rich repeat protein phosphatase-1 (PHLPP1), triggering its degradation by ubiquitination. Furthermore, SKP2 activates the AKT-related pathways via PHLPP1, which leads to the cytoplasmic translocation of SKP2, indicating a reciprocal regulation between SKP2 and AKT. In conclusion, the upregulation of SKP2 leads to PTC proliferation and survival, and the regulatory network among SKP2, PHLPP1, and AKT provides novel insight into the molecular basis of SKP2 in tumor progression.