Rhabdovirus Infection Is Dependent on Serine/Threonine Kinase AP2-Associated Kinase 1

Numb-associated kinases regulate sandfly-borne Toscana virus entry

Sandfly-borne Toscana virus (TOSV) is an enveloped tri-segmented negative single-strand RNA Phlebovirus. It is an emerging virus predominantly endemic in southwestern Europe and Northern Africa. Although TOSV infection is typically asymptomatic or results in mild febrile disease, it is neurovirulent and ranks among the three most common causes of summer meningitis in certain regions. Despite this clinical significance, our understanding of the molecular aspects and host factors regulating phlebovirus infection is limited.This study characterized the early steps of TOSV infection. Our findings reveal that two members of the Numb-associated kinases family of Ser/Thr kinases, namely adaptor-associated kinase 1 (AAK1) and cyclin G-associated kinase (GAK), play a role in regulating the early stages of TOSV entry. FDA-approved inhibitors targeting these kinases demonstrated significant inhibition of TOSV infection. This study suggests that AAK1 and GAK represent druggable targets for inhibiting TOSV infection and, potentially, related Phleboviruses.

TRIM25 Suppresses Rabies Virus Fixed HEP-Flury Strain Production by Activating RIG-1-Mediated Type I Interferons

Rabies remains a great threat to public health worldwide. So far, the mechanism of rabies virus (RABV) infection is not fully understood, and there is no effective treatment for rabies. Identifying more host restriction factors of RABV will spur the development of novel therapeutic interventions against rabies. Accumulating studies suggest that tripartite motif-containing (TRIM) proteins have great effects on virus replication. TRIMs control the antiviral responses through either direct interaction with viral proteins or indirect regulation of innate immune signaling molecules in the host. The role of TRIM25 in rabies virus (RABV) infection is poorly understood. Using next-generation sequencing, we found that TRIM25 is upregulated during HEP-Flury infection. Knockdown of TRIM25 enhances HEP-Flury production, while overexpression of TRIM25 suppresses HEP-Flury replication. Knockdown of interferon α and interferon β weakens the anti-RABV response induced by TRIM25 overexpression, and potentiates RABV production. Furthermore, we found that TRIM25 regulates type-I interferon response by targeting retinoic acid-inducible gene I (RIG-I) during HEP-Flury infection. Knockdown of RIG-I weakens the anti-HEP-Flury response induced by TRIM25 overexpression, indicating that TRIM25 regulates RABV production via the RIG-I-IFN axis. In addition, we observed that TRIM25 does not directly interact with HEP-Flury structural proteins, suggesting that TRIM25 regulates HEP-Flury production indirectly. Taken together, our work identifies TRIM25 as a new host factor involved in HEP-Flury infection, which may be a potential target for the development of antiviral drugs against RABV.

TRIM21 Promotes Rabies Virus Production by Degrading IRF7 through Ubiquitination

Rabies, a highly fatal zoonotic disease, is a significant global public health threat. Currently, the pathogenic mechanism of rabies has not been fully elucidated, and no effective treatment for rabies is available. Increasing evidence shows that the tripartite-motif protein (TRIM) family of proteins participates in the host's regulation of viral replication. Studies have demonstrated the upregulated expression of tripartite-motif protein 21 (TRIM21) in the brain tissue of mice infected with the rabies virus. Related studies have shown that TRIM21 knockdown inhibits RABV replication, while overexpression of TRIM21 exerted the opposite effect. Knockdown of interferon-alpha and interferon-beta modulates the inhibition of RABV replication caused by TRIM21 knockdown and promotes the replication of the virus. Furthermore, our previous study revealed that TRIM21 regulates the secretion of type I interferon during RABV infection by targeting interferon regulatory factor 7 (IRF7). IRF7 knockdown reduced the inhibition of RABV replication caused by the knockdown of TRIM21 and promoted viral replication. TRIM21 regulates RABV replication via the IRF7-IFN axis. Our study identified TRIM21 as a novel host factor required by RABV for replication. Thus, TRIM21 is a potential target for rabies treatment or management.

Transferrin Receptor Protein 1 Is an Entry Factor for Rabies Virus

Rabies virus (RABV) is a prototypical neurotropic virus that causes rabies in human and animals with an almost 100% mortality rate. Once RABV enters the central nervous system, no treatment is proven to prevent death. RABV glycoprotein (G) interacts with cell surface receptors and then enters cells via clathrin-mediated endocytosis (CME); however, the key host factors involved remain largely unknown. Here, we identified transferrin receptor 1 (TfR1), a classic receptor that undergoes CME, as an entry factor for RABV. TfR1 interacts with RABV G and is involved in the endocytosis of RABV. An antibody against TfR1 or the TfR1 ectodomain soluble protein significantly blocked RABV infection in HEK293 cells, N2a cells, and mouse primary neuronal cells. We further found that the endocytosis of TfR1 is coupled with the endocytosis of RABV and that TfR1 and RABV are transported to early and late endosomes. Our results suggest that RABV hijacks the transport pathway of TfR1 for entry, thereby deepening our understanding of the entry mechanism of RABV. IMPORTANCE For most viruses, cell entry involves engagement with many distinct plasma membrane components, each of which is essential. After binding to its specific receptor(s), rabies virus (RABV) enters host cells through the process of clathrin-mediated endocytosis. However, whether the receptor-dependent clathrin-mediated endocytosis of RABV requires other plasma membrane components remain largely unknown. Here, we demonstrate that transferrin receptor 1 (TfR1) is a functional entry factor for RABV infection. The endocytosis of RABV is coupled with the endocytosis of TfR1. Our results indicate that RABV hijacks the transport pathway of TfR1 for entry, which deepens our understanding of the entry mechanism of RABV.

Development and therapeutic potential of adaptor-associated kinase 1 inhibitors in human multifaceted diseases

Adaptor-Associated Kinase 1 (AAK1), a Ser/Thr protein kinase, responsible for regulating clathrin-mediated endocytosis, is ubiquitous in the central nervous system (CNS). AAK1 plays an important role in neuropathic pain and a variety of other human diseases, including viral invasion, Alzheimer's disease, Parkinson's syndrome, etc. Therefore, targeting AAK1 is a promising therapeutic strategy. However, although small molecule AAK1 inhibitors have been vigorously developed, only BMS-986176/LX-9211 has entered clinical trials. Simultaneously, new small molecule inhibitors, including BMS-911172 and LP-935509, exhibited excellent druggability. This review elaborates on the structure, biological function, and disease relevance of AAK1. We emphatically analyze the structure-activity relationships (SARs) of small molecule AAK1 inhibitors based on different binding modalities and discuss prospective strategies to provide insights into novel AAK1 therapeutic agents for clinical practice.

FDA-Approved Kinase Inhibitors in Preclinical and Clinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases. We previously developed a new concept termed "Aberrant Cell Cycle Diseases" (ACCD), revealing that these two diseases share a common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncogene activation and tumor suppressor inactivation, which are hallmarks of both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase inhibition, tumor suppressor elevation) can be leveraged for neurological treatments. The United States Food and Drug Administration (US FDA) has so far approved 74 kinase inhibitors, with numerous other kinase inhibitors in clinical trials, mostly for the treatment of cancers. In contrast, there are dire unmet needs of FDA-approved drugs for neurological treatments, such as Alzheimer's disease (AD), intracerebral hemorrhage (ICH), ischemic stroke (IS), traumatic brain injury (TBI), and others. In this review, we list these 74 FDA-approved kinase-targeted drugs and identify those that have been reported in preclinical and/or clinical trials for neurological disorders, with a purpose of discussing the feasibility and applicability of leveraging these cancer drugs (FDA-approved kinase inhibitors) for neurological treatments.

Interleukin-25 enhances humoral immune responses caused by the rabies virus

Rabies is an important zoonotic disease caused by the rabies virus (RABV). Currently, no effective treatment is available for this condition. The prevention and control of rabies mainly depend on effective vaccination. Therefore, it is crucial to enhance the immune responses induced by the rabies vaccine. Virus neutralizing antibodies (VNA) induced by rabies vaccines are important for the clearance of RABV. Interleukin-25 (IL-25) has been demonstrated to activate T helper type 2 cells that contribute to humoral immune responses. The IL-25 gene was inserted into the genome of RABV, and the immunogenicity of recombinant RABV with IL-25 gene was investigated to develop more efficient rabies vaccines. Here, we found that the expression of IL-25 did not affect RABV production in vitro and pathogenicity in vivo. However, recombinant RABV expression of IL-25 induced a better VNA level than the parental virus in mice. In addition, expression of IL-25 enhanced the IgG1 level induced by RABV. Furthermore, mice immunized with recombinant RABV showed a higher survival rate and milder clinical signs than those immunized with the parent strain after challenge with CVS-11. Thus, these results showed that IL-25 could enhance the humoral immune responses induced by RABV, suggesting that IL-25 can be used as a viral vaccine adjuvant.

A patent review of adaptor associated kinase 1 (AAK1) inhibitors (2013-present)

INTRODUCTION

Adaptor-associated kinase 1 (AAK1) has been proposed as being a promising drug target for the treatment of a variety of neurological and psychiatric disorders, such as schizophrenia, cognitive deficits in schizophrenia, Parkinson's disease, bipolar disorder, Alzheimer's disease and neuropathic pain. More recently, AAK1 was shown to be an essential cellular factor for viral replication and therefore has been pursued as a host target for the development of broad-spectrum antiviral agents.

AREAS COVERED

This review provides an overview of the patented AAK1 inhibitors from 2013 to present.

EXPERT OPINION

The promise of AAK1 as drug target for the treatment of neuropathic pain stimulated the search for AAK1 inhibitors. However, only two companies (i.e. Lexicon Pharmaceuticals and Bristol Myers Squibb) seemed to be active in this field and filed patent applications in the last few years. The most promising congeners showed promising in vitro activity in a variety of AAK1-related assays. Moreover, selected compounds were also endowed with in vivo activity in various preclinical animal models for neuropathic pain.