The E3 ubiquitin ligase MARCH1 regulates antimalaria immunity through interferon signaling and T cell activation

E3 ubiquitin ligase MARCH5 positively regulates Japanese encephalitis virus infection by catalyzing the K27-linked polyubiquitination of viral E protein and inhibiting MAVS-mediated type I interferon production

Membrane-associated RING-CH-type finger (MARCH) proteins, a class of E3 ubiquitin ligases, have been reported to be involved in the infection of multiple viruses and the regulation of type I interferon (IFN) production. However, the specific role and mechanisms by which MARCH proteins influence Japanese encephalitis virus (JEV) infection remain poorly understood. Here, we systematically investigate the functional relevance of MARCH proteins in JEV replication by examining the effects of siRNA-mediated knockdown of MARCHs on viral infection. We identified MARCH5 as a positive regulator of JEV replication. The knockout of MARCH5 dramatically reduced viral yields, whereas its overexpression significantly enhanced JEV replication. Mechanistically, MARCH5 specifically interacts with the JEV envelope (E) protein and promotes its K27-linked polyubiquitination at the lysine (K) residues 136 and 166. This ubiquitination enhances viral attachment to permissive cells. Substituting these lysine residues with arginine (R) attenuated JEV replication in vitro and reduced viral virulence in vivo. Furthermore, JEV infection upregulated the expression of MARCH5. We also discovered that MARCH5 degrades mitochondrial antiviral-signaling protein (MAVS) through the ubiquitin-proteasome pathway by catalyzing its K48-linked ubiquitination, thereby inhibiting type I IFN production in JEV-infected cells. This suppression of type I IFN further facilitates JEV infection. In conclusion, these findings disclosed a novel role of MARCH5 in positively regulating JEV infection and revealed an important mechanism employed by MARCH5 to regulate the innate immune response.IMPORTANCEJEV is the leading cause of viral encephalitis in many countries of Asia with an estimated 100,000 clinical human cases and causes economic loss to the swine industry. Until now, there is no clinically approved antiviral for the treatment of JEV infection. Although vaccination prophylaxis is widely regarded as the most effective strategy for preventing Japanese encephalitis (JE), the incidence of JE cases continues to rise. Thus, a deeper understanding of virus-host interaction will enrich our knowledge of the mechanisms underlying JEV infection and identify novel targets for the development of next-generation live-attenuated vaccines and antiviral therapies. To the best of our knowledge, this study is the first to identify MARCH5 as a pro-viral host factor that facilitates JEV infection. We elucidated two distinct mechanisms by which MARCH5 promotes JEV infection. First, MARCH5 interacts with viral E protein and mediates the K27-linked ubiquitination of E protein at the K136 and K166 residues to facilitate efficient viral attachment. Furthermore, double mutations of K136R-K166R attenuated JEV infection in vitro and reduced viral virulence in mice. Second, the upregulated expression of MARCH5 induced by JEV infection further suppresses the RIG-I-like receptor (RLR) signaling pathway to benefit viral infection. MARCH5 downregulates type I IFN production by conjugating the K48-linked polyubiquitin at the K286 of MAVS, which leads to MAVS degradation through the ubiquitin-proteasome pathway. In summary, this study provides novel insights into the role played by MARCH proteins in JEV infection and identifies specific ubiquitination sites on JEV E protein that could be targeted for viral attenuation and the development of antiviral therapeutics.

MARCHF1 promotes breast cancer through accelerating REST ubiquitylation and following TFAM transcription

Breast cancer has become the leading cause of death in women. Membrane associated ring-CH-type finger 1 (MARCHF1) is associated with the development of various types of cancer, but the exact role of MARCHF1 in breast cancer remains unclear. In our study, the higher MARCHF1 expression was observed in tumor samples of patients with breast cancer and then the role of MARCHF1 in breast cancer was further evaluated. Overexpression of MARCHF1 contributed to proliferation of cancer cells and inhibition of oxidative stress. Knockdown of MARCHF1 reduced breast cancer cell proliferation, increased mitochondrial dysfunction induced by oxidative stress, eventually aggravating cell death. In vivo, MARCHF1 promoted the tumor growth and oppositely, MARCHF1 silencing suppressed the tumor development. Moreover, MARCHF1 interacted with repressor Element-1 silencing transcription factor (REST) and facilitated its ubiquitylation and degradation. Subsequently, REST negatively regulated the transcription of mitochondrial transcription factor A (TFAM). The subcutaneous tumor formation assay in nude mice also supported these conclusions. In details, knockdown of MARCHF1 upregulated the protein expression of REST and downregulated the mRNA level of TFAM. On the contrary, MARCHF1 overexpression exhibited opposite effects. Thus, MARCHF1 is conducive to the progression of breast cancer via promoting the ubiquitylation and degradation of RSET and then the transcription of TFAM. Downregulating MARCHF1 could provide a novel direction for treating breast cancer.

Malaria: Factors affecting disease severity, immune evasion mechanisms, and reversal of immune inhibition to enhance vaccine efficacy

Malaria is a complex parasitic disease caused by species of Plasmodium parasites. Infection with the parasites can lead to a spectrum of symptoms and disease severity, influenced by various parasite, host, and environmental factors. There have been some successes in developing vaccines against the disease recently, but the vaccine efficacies require improvement. Some issues associated with the difficulties in developing a sterile vaccine include high antigenic diversity, switching expression of the immune targets, and inhibition of immune pathways. Current vaccine research focuses on identifying conserved and protective epitopes, developing multivalent vaccines (including the whole parasite), and using more powerful adjuvants. However, overcoming the systematic immune inhibition and immune cell dysfunction/exhaustion may be required before high titers of protective antibodies can be achieved. Increased expression of surface molecules such as CD86 and MHC II on antigen-presenting cells and blocking immune checkpoint pathways (interactions of PD-1 and PD-L1; CTLA-4 and CD80) using small molecules could be a promising approach for enhancing vaccine efficacy. This assay reviews the factors affecting the disease severity, the genetics of host-parasite interaction, immune evasion mechanisms, and approaches potentially to improve host immune response for vaccine development.

Curcumin Inhibits the Growth of Hepatocellular Carcinoma via the MARCH1-mediated Modulation of JAK2/STAT3 Signaling

BACKGROUND

Curcumin has been reported to have anti-hepatocellular carcinoma (HCC) effects, but the underlying mechanism is not well known.

OBJECTIVES

To investigate whether membrane-associated RING-CH 1 (MARCH1) is involved in the curcumin-induced growth suppression in HCC and its underlying molecular mechanism. A few recent patents for curcumin for cancer are also reviewed in this article.

METHODS

The effect of curcumin on growth inhibition of HCC cells was analyzed through in vitro and in vivo experiments, and the expression levels of MARCH1, Bcl-2, VEGF, cyclin B1, cyclin D1, and JAK2/STAT3 signaling molecules were measured in HCC cells and the xenograft tumors in nude mice. Cell transfection with MARCH1 siRNAs or expression plasmid was used to explore the role of MARCH1 in the curcumin-induced growth inhibition of HCC cells.

RESULTS

Curcumin inhibited cell proliferation, promoted apoptosis, and arrested the cell cycle at the G2/M phase in HCC cells with the decrease of Bcl-2, VEGF, cyclin B1, and cyclin D1 expression as well as JAK2 and STAT3 phosphorylation, resulting in the growth suppression of HCC cells. MARCH1 is highly expressed in HCC cells, and its expression was downregulated after curcumin treatment in a dose-dependent manner. The knockdown of MARCH1 by siRNA decreased the phosphorylation levels of JAK2 and STAT3 and inhibited the growth of HCC cells. In contrast, opposite results were observed when HCC cells overexpressed MARCH1. A xenograft tumor model in nude mice also showed that curcumin downregulated MARCH1 expression and decelerated the growth of transplanted HCC with the downregulation of JAK2/STAT3 signaling and functional molecules. The ADC value of MRI analysis showed that curcumin slowed down the progression of HCC.

CONCLUSION

Our results demonstrated that curcumin may inhibit the activation of JAK2/STAT3 signaling pathway by downregulating MARCH1 expression, resulting in the growth suppression of HCC. MARCH1 may be a novel target of curcumin in HCC treatment.

Gene Expression and Alternative Splicing Analysis in a Large-Scale Multiple Sclerosis Study

Multiple Sclerosis (MS) is an autoimmune neurodegenerative disease affecting approximately 3 million people globally. Despite rigorous research on MS, aspects of its development and progression remain unclear. We utilized a publicly available RNA-seq dataset (GSE138614) consisting of the post-mortem white matter tissues of five donors without any neurological disorders and ten MS patient donors. We investigated gene expression levels correlated with tissue inflammation and alternative splicing to identify possible pathological isoforms in MS tissues. We identified RNA-binding motifs, differentially expressed RNA-binding proteins, and single-nucleotide polymorphisms (SNPs) to unravel possible mechanisms of alternative splicing. Genes with expression changes that were positively correlated with tissue inflammation were enriched in the immune system and receptor interaction pathways. Genes showing a negative correlation were enriched in nervous system development and in metabolic pathways. A comparison of normal-appearing white matter (NAWM) and active or chronic active lesions within the same donors identified genes playing roles in immunity, white matter injury repair, and remyelination. We identified exon skipping events and spontaneous SNPs in membrane-associated ring-CH-type finger-1 (MARCHF1), UDP glycosyltransferase-8 (UGT8), and other genes important in autoimmunity and neurodegeneration. Overall, we identified unique genes, pathways, and novel splicing events that can be further investigated as potential novel drug targets for MS treatment.

Dual nature of type I interferon responses and feedback regulations by SOCS1 dictate malaria mortality

INTRODUCTION

Type I interferon (IFN-I, IFN-α/β), precisely controlled by multiple regulators, including suppressor of cytokine signaling 1 (SOCS1), is critical for host defense against pathogens. However, the impact of IFN-α/β on malaria parasite infections, beneficial or detrimental, remains controversial.

OBJECTIVES

The contradictory results are suspected to arise from differences in parasite species and host genetic backgrounds. To date, no prior study has employed a comparative approach utilizing two parasite models to investigate the underlying mechanisms of IFN-I response. Moreover, whether and how SOCS1 involves in the distinct IFN-α/β dynamics is still unclear.

METHODS

Here we perform single-cell RNA sequencing analyses (scRNA-seq) to dissect the dynamics of IFN-α/β responses against P. yoelii 17XL (17XL) and P. berghei ANKA (PbANKA) infections; conduct flow cytometry analysis and functional depletion to identify key cellular players induced by IFN-I; and establish mathematical models to explore the mechanisms underlying the differential IFN-I dynamics regulated by SOCS1.

RESULTS

17XL stimulates an early protective but insufficient toll-like receptor 7 (TLR7)-interferon regulatory factor 7 (IRF7)-dependent IFN-α/β response, resulting in CD11ahiCD49dhiCD4+ T cell activation to enhance anti-malarial immunity. On the contrary, a late IFN-α/β induction through toll-like receptor 9 (TLR9)-IRF7/ stimulator of interferon genes (STING)- interferon regulatory factor 3 (IRF3) dependent pathways expands programmed cell death protein 1 (PD-1)+CD8+ T cells and impairs host immunity during PbANKA infection. Furthermore, functional assay and mathematical modeling show that SOCS1 significantly suppresses IFN-α/β production via negative feedback and incoherent feed-forward loops (I1-FFL). Additionally, differential activation patterns of various transcriptional factors (TFs) synergistically regulate the distinct IFN-I responses.

CONCLUSION

This study reveals the dual functions of IFN-I in anti-malarial immunity: Early IFN-α/β enhances immune responses against Plasmodium infection by promoting CD11ahiCD49dhiCD4+ T cell, while late IFN-α/β suppresses these response by expanding PD-1+CD8+ T cells. Moreover, both the SOCS1-related network motifs and TFs activation patterns contribute to determine distinct dynamics of IFN-I responses. Hence, our findings suggest therapies targeting SOCS1- or TFs-regulated IFN-I dynamics could be an efficacious approach for preventing malaria and enhancing vaccine efficacy.

Gene expression and alternative splicing analysis in a large-scale Multiple Sclerosis study

Background

Multiple Sclerosis (MS) is an autoimmune neurodegenerative disease affecting approximately 3 million people globally. Despite rigorous research on MS, aspects of its development and progression remain unclear. Understanding molecular mechanisms underlying MS is crucial to providing insights into disease pathways, identifying potential biomarkers for early diagnosis, and revealing novel therapeutic targets for improved patient outcomes.

Methods

We utilized publicly available RNA-seq data (GSE138614) from post-mortem white matter tissues of five donors without any neurological disorder and ten MS patient donors. This data was interrogated for differential gene expression, alternative splicing and single nucleotide variants as well as for functional enrichments in the resulting datasets.

Results

A comparison of non-MS white matter (WM) to MS samples yielded differentially expressed genes involved in adaptive immune response, cell communication, and developmental processes. Genes with expression changes positively correlated with tissue inflammation were enriched in the immune system and receptor interaction pathways. Negatively correlated genes were enriched in neurogenesis, nervous system development, and metabolic pathways. Alternatively spliced transcripts between WM and MS lesions included genes that play roles in neurogenesis, myelination, and oligodendrocyte differentiation, such as brain enriched myelin associated protein (BCAS1), discs large MAGUK scaffold protein 1 (DLG1), KH domain containing RNA binding (QKI), and myelin basic protein (MBP). Our approach to comparing normal appearing WM (NAWM) and active lesion (AL) from one donor and NAWM and chronic active (CA) tissues from two donors, showed that different IgH and IgK gene subfamilies were differentially expressed. We also identified pathways involved in white matter injury repair and remyelination in these tissues. Differentially spliced genes between these lesions were involved in axon and dendrite structure stability. We also identified exon skipping events and spontaneous single nucleotide polymorphisms in membrane associated ring-CH-type finger 1 (MARCHF1), UDP glycosyltransferase 8 (UGT8), and other genes important in autoimmunity and neurodegeneration.

Conclusion

Overall, we identified unique genes, pathways, and novel splicing events affecting disease progression that can be further investigated as potential novel drug targets for MS treatment.

MARCH1 negatively regulates TBK1-mTOR signaling pathway by ubiquitinating TBK1

BACKGROUND

TBK1 positively regulates the growth factor-mediated mTOR signaling pathway by phosphorylating mTOR. However, it remains unclear how the TBK1-mTOR signaling pathway is regulated. Considering that STING not only interacts with TBK1 but also with MARCH1, we speculated that MARCH1 might regulate the mTOR signaling pathway by targeting TBK1. The aim of this study was to determine whether MARCH1 regulates the mTOR signaling pathway by targeting TBK1.

METHODS

The co-immunoprecipitation (Co-IP) assay was used to verify the interaction between MARCH1 with STING or TBK1. The ubiquitination of STING or TBK1 was analyzed using denatured co-immunoprecipitation. The level of proteins detected in the co-immunoprecipitation or denatured co-immunoprecipitation samples were determined by Western blotting. Stable knocked-down cells were constructed by infecting lentivirus bearing the related shRNA sequences. Scratch wound healing and clonogenic cell survival assays were used to detect the migration and proliferation of breast cancer cells.

RESULTS

We showed that MARCH1 played an important role in growth factor-induced the TBK1- mTOR signaling pathway. MARCH1 overexpression attenuated the growth factor-induced activation of mTOR signaling pathway, whereas its deficiency resulted in the opposite effect. Mechanistically, MARCH1 interacted with and promoted the K63-linked ubiquitination of TBK1. This ubiquitination of TBK1 then attenuated its interaction with mTOR, thereby inhibiting the growth factor-induced mTOR signaling pathway. Importantly, faster proliferation induced by MARCH1 deficiency was weakened by mTOR, STING, or TBK1 inhibition.

CONCLUSION

MARCH1 suppressed growth factors mediated the mTOR signaling pathway by targeting the STING-TBK1-mTOR axis.

NAD activates olfactory receptor 1386 to regulate type I interferon responses in Plasmodium yoelii YM infection

Olfactory receptors (Olfr) are G protein-coupled receptors that are normally expressed on olfactory sensory neurons to detect volatile chemicals or odorants. Interestingly, many Olfrs are also expressed in diverse tissues and function in cell-cell recognition, migration, and proliferation as well as immune responses and disease processes. Here, we showed that many Olfr genes were expressed in the mouse spleen, linked to Plasmodium yoelii genetic loci significantly, and/or had genome-wide patterns of LOD scores (GPLSs) similar to those of host Toll-like receptor genes. Expression of specific Olfr genes such as Olfr1386 in HEK293T cells significantly increased luciferase signals driven by IFN-β and NF-κB promoters, with elevated levels of phosphorylated TBK1, IRF3, P38, and JNK. Mice without Olfr1386 were generated using the CRISPR/Cas9 method, and the Olfr1386-/- mice showed significantly lower IFN-α/β levels and longer survival than wild-type (WT) littermates after infection with P. yoelii YM parasites. Inhibition of G protein signaling and P38 activity could affect cyclic AMP-responsive element promoter-driven luciferase signals and IFN-β mRNA levels in HEK293T cells expressing the Olfr1386 gene, respectively. Screening of malaria parasite metabolites identified nicotinamide adenine dinucleotide (NAD) as a potential ligand for Olfr1386, and NAD could stimulate IFN-β responses and phosphorylation of TBK1 and STAT1/2 in RAW264.7 cells. Additionally, parasite RNA (pRNA) could significantly increase Olfr1386 mRNA levels. This study links multiple Olfrs to host immune response pathways, identifies a candidate ligand for Olfr1386, and demonstrates the important roles of Olfr1386 in regulating type I interferon (IFN-I) responses during malaria parasite infections.

Human MARCH1, 2, and 8 block Ebola virus envelope glycoprotein cleavage via targeting furin P domain

Membrane-associated RING-CH (MARCH) family proteins were recently reported to inhibit viral replication through multiple modes. Previous work showed that human MARCH8 blocked Ebola virus (EBOV) glycoprotein (GP) maturation. Our study here demonstrates that human MARCH1 and MARCH2 share a similar pattern to MARCH8 in restricting EBOV GP-pseudotyped viral infection. Human MARCH1 and MARCH2 retain EBOV GP at the trans-Golgi network, reduce its cell surface display, and impair EBOV GP-pseudotyped virions infectivity. Furthermore, we uncover that the host proprotein convertase furin could interact with human MARCH1/2 and EBOV GP intracellularly. Importantly, the furin P domain is verified to be recognized by MARCH1/2/8, which is critical for their blocking activities. Besides, bovine MARCH2 and murine MARCH1 also impair EBOV GP proteolytic processing. Altogether, our findings confirm that MARCH1/2 proteins of different mammalian origins showed a relatively conserved feature in blocking EBOV GP cleavage, which could provide clues for subsequent MARCHs antiviral studies and may facilitate the development of novel strategies to antagonize enveloped virus infection.

Exosome‑delivered miR‑486‑3p inhibits the progression of osteosarcoma via sponging CircKEAP1/MARCH1 axis components

Accumulating evidence shows that the disruption of competing endogenous RNA (ceRNA) networks plays a significant role in osteosarcoma (OS) initiation and progression. However, the specific roles and functions of the ceRNAs in OS remain unclear. First, differentially expressed microRNAs (DEMs) were identified by mining the E-MTAB-1136 and GSE28423 datasets. MiRWalk website was used to predict the target gene of miRNA. OS-associated circular RNA (circRNA) expression profiles were downloaded from the published microarray databases. Gene expression levels were assessed through reverse transcription-quantitative PCR and western blotting. The biological effects of circKEAP1, microRNA (miR)-486-3p and membrane-associated RINGCH finger protein 1 (MARCH1) in OS cells were investigated using Cell Counting Kit-8, Transwell, colony formation and wound healing assays. miR-486-3p was aberrantly downregulated in OS tissues and cell lines and was packed with exosomes. miR-486-3p overexpression was shown to inhibit OS cell progression and promoted cell cycle arrest in vitro. In addition, MARCH1 was identified as a direct downstream molecule of miR-486-3p in OS cells. circKEAP1 was found to be upregulated in OS tissues and cells. circKEAP1 was found to have binding sites with miR-486-3p. Mechanistically, circKEAP1 positively regulated MARCH1 expression by sponging miR-486-3p. Exosomal miR-486-3p inhibited the progression of OS by sponging the circKEAP1/MARCH1 axis. These findings may provide a promising treatment approach for OS.

SHIP1 modulates antimalarial immunity by bridging the crosstalk between type I IFN signaling and autophagy

Stringent control of the type I interferon (IFN-I) signaling is critical for host immune defense against infectious diseases, yet the molecular mechanisms that regulate this pathway remain elusive. Here, we show that Src homology 2 containing inositol phosphatase 1 (SHIP1) suppresses IFN-I signaling by promoting IRF3 degradation during malaria infection. Genetic ablation of Ship1 in mice leads to high levels of IFN-I and confers resistance to Plasmodium yoelii nigeriensis (P.y.) N67 infection. Mechanistically, SHIP1 promotes the selective autophagic degradation of IRF3 by enhancing K63-linked ubiquitination of IRF3 at lysine 313, which serves as a recognition signal for NDP52-mediated selective autophagic degradation. In addition, SHIP1 is downregulated by IFN-I-induced miR-155-5p upon P.y. N67 infection and severs as a feedback loop of the signaling crosstalk. This study reveals a regulatory mechanism between IFN-I signaling and autophagy, and verifies SHIP1 can be a potential target for therapeutic intervention against malaria and other infectious diseases. IMPORTANCE Malaria remains a serious disease affecting millions of people worldwide. Malaria parasite infection triggers tightly controlled type I interferon (IFN-I) signaling that plays a critical role in host innate immunity; however, the molecular mechanisms underlying the immune responses are still elusive. Here, we discover a host gene [Src homology 2-containing inositol phosphatase 1 (SHIP1)] that can regulate IFN-I signaling by modulating NDP52-mediated selective autophagic degradation of IRF3 and significantly affect parasitemia and resistance of Plasmodium-infected mice. This study identifies SHIP1 as a potential target for immunotherapies in malaria and highlights the crosstalk between IFN-I signaling and autophagy in preventing related infectious diseases. SHIP1 functions as a negative regulator during malaria infection by targeting IRF3 for autophagic degradation.

Regulation of MHC class II and CD86 expression by March-I in immunity and disease

The expression of MHC-II and CD86 on the surface of antigen-presenting cells (APCs) must be tightly regulated to foster antigen-specific CD4 T-cell activation and to prevent autoimmunity. Surface expression of these proteins is regulated by their dynamic ubiquitination by the E3 ubiquitin ligase March-I. March-I promotes turnover of peptide-MHC-II complexes on resting APCs and termination of March-I expression promotes MHC-II and CD86 surface stability. In this review, we will highlight recent studies examining March-I function in both normal and pathological conditions.

Targeted Protein Degradation for Infectious Diseases: from Basic Biology to Drug Discovery

Targeted protein degradation (TPD) is emerging as one of the most innovative strategies to tackle infectious diseases. Particularly, proteolysis-targeting chimera (PROTAC)-mediated protein degradation may offer several benefits over classical anti-infective small-molecule drugs. Because of their peculiar and catalytic mechanism of action, anti-infective PROTACs might be advantageous in terms of efficacy, toxicity, and selectivity. Importantly, PROTACs may also overcome the emergence of antimicrobial resistance. Furthermore, anti-infective PROTACs might have the potential to (i) modulate "undruggable" targets, (ii) "recycle" inhibitors from classical drug discovery approaches, and (iii) open new scenarios for combination therapies. Here, we try to address these points by discussing selected case studies of antiviral PROTACs and the first-in-class antibacterial PROTACs. Finally, we discuss how the field of PROTAC-mediated TPD might be exploited in parasitic diseases. Since no antiparasitic PROTAC has been reported yet, we also describe the parasite proteasome system. While in its infancy and with many challenges ahead, we hope that PROTAC-mediated protein degradation for infectious diseases may lead to the development of next-generation anti-infective drugs.

Function and regulation of cGAS-STING signaling in infectious diseases

The efficacious detection of pathogens and prompt induction of innate immune signaling serve as a crucial component of immune defense against infectious pathogens. Over the past decade, DNA-sensing receptor cyclic GMP-AMP synthase (cGAS) and its downstream signaling adaptor stimulator of interferon genes (STING) have emerged as key mediators of type I interferon (IFN) and nuclear factor-κB (NF-κB) responses in health and infection diseases. Moreover, both cGAS-STING pathway and pathogens have developed delicate strategies to resist each other for their survival. The mechanistic and functional comprehension of the interplay between cGAS-STING pathway and pathogens is opening the way for the development and application of pharmacological agonists and antagonists in the treatment of infectious diseases. Here, we briefly review the current knowledge of DNA sensing through the cGAS-STING pathway, and emphatically highlight the potent undertaking of cGAS-STING signaling pathway in the host against infectious pathogenic organisms.

Genetic mapping of determinants in drug resistance, virulence, disease susceptibility, and interaction of host-rodent malaria parasites

Genetic mapping has been widely employed to search for genes linked to phenotypes/traits of interest. Because of the ease of maintaining rodent malaria parasites in laboratory mice, many genetic crosses of rodent malaria parasites have been performed to map the parasite genes contributing to malaria parasite development, drug resistance, host immune response, and disease pathogenesis. Drs. Richard Carter, David Walliker, and colleagues at the University of Edinburgh, UK, were the pioneers in developing the systems for genetic mapping of malaria parasite traits, including characterization of genetic markers to follow the inheritance and recombination of parasite chromosomes and performing the first genetic cross using rodent malaria parasites. Additionally, many genetic crosses of inbred mice have been performed to link mouse chromosomal loci to the susceptibility to malaria parasite infections. In this chapter, we review and discuss past and recent advances in genetic marker development, performing genetic crosses, and genetic mapping of both parasite and host genes. Genetic mappings using models of rodent malaria parasites and inbred mice have contributed greatly to our understanding of malaria, including parasite development within their hosts, mechanism of drug resistance, and host-parasite interaction.

Isoforms of Human MARCH1 Differ in Ability to Restrict Influenza A Viruses Due to Differences in Their N Terminal Cytoplasmic Domain

MARCH1 and MARCH8 are closely related E3 ubiquitin ligases that ubiquitinate an overlapping spectrum of host proteins and restrict replication of certain viruses. While the antiviral activity of MARCH8 has been intensively studied, less is known regarding virus inhibition by MARCH1. Isoforms 1 and 2 of MARCH1 are very similar in overall structure but show major differences in their N-terminal cytoplasmic domain (N-CT). Herein, we used a doxycycline-inducible overexpression system to demonstrate that MARCH1.1 reduces titres of influenza A virus (IAV) released from infected cells whereas MARCH1.2 does not. The deletion of the entire N-CT of MARCH1.2 restored its ability to restrict IAV infectivity and sequential deletions mapped the restoration of IAV inhibition to delete the 16 N-terminal residues within the N-CT of MARCH1.2. While only MARCH1.1 mediated anti-IAV activity, qPCR demonstrated the preferential expression of MARCH1.2 over MARCH1.1 mRNA in unstimulated human peripheral blood mononuclear cells and also in monocyte-derived macrophages. Together, these studies describe the differential ability of MARCH1 isoforms to restrict IAV infectivity for the first time. Moreover, as published immunological, virological and biochemical studies examining the ability of MARCH1 to target particular ligands generally use only one of the two isoforms, these findings have broader implications for our understanding of how MARCH1 isoforms might differ in their ability to modulate particular host and/or viral proteins.

Targeting UBR5 in hepatocellular carcinoma cells and precise treatment via echinacoside nanodelivery

Background

Hepatocellular carcinoma (HCC) is among the most common and malignant cancers with no effective therapeutic approaches. Echinacoside (ECH), a phenylethanoid glycoside isolated from Chinese herbal medicine, Cistanche salsa, can inhibit HCC progression; however, poor absorption and low bioavailability limit its biological applications.

Methods

To improve ECH sensitivity to HepG2 cells, we developed a mesoporous silica nanoparticle (MSN)-based drug delivery system to deliver ECH to HepG2 cells via galactose (GAL) and poly(ethylene glycol) diglycidyl ether (PEGDE) conjugation (ECH@Au@MSN-PEGDE-GAL, or ECH@AMPG). Gain- and loss-of-function assays were conducted to assess the effects of UBR5 on HCC cell apoptosis and glycolysis. Moreover, the interactions among intermediate products were also investigated to elucidate the mechanisms by which UBR5 functions.

Results

The present study showed that ubiquitin protein ligase E3 component N-recognin 5 (UBR5) acted as an oncogene in HCC tissues and that its expression was inhibited by ECH. AMPG showed a high drug loading property and a slow and sustained release pattern over time. Moreover, owing to the valid drug accumulation, ECH@AMPG promoted apoptosis and inhibited glycolysis of HepG2 cells in vitro. In vivo experiments demonstrated that AMPG also enhanced the antitumor effects of ECH in HepG2 cell-bearing mice.

Conclusions

Our results indicated the clinical significance of UBR5 as a therapeutic target. On the basis of the nontoxic and high drug-loading capabilities of AMPG, ECH@AMPG presented better effects on HCC cells compared with free ECH, indicating its potential for the chemotherapy of HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00394-w.

Epitranscriptome profiling of spleen mRNA m6A methylation reveals pathways of host responses to malaria parasite infection

N6 -Methyladenosine (m6A), the most abundant mammalian mRNA modification, has been reported to modulate various viral infections. Although it has been confirmed that RNA modifications can also modulate the replication and development of different parasites, the role of the RNA epitranscriptome in the regulation of host response post parasite infection remains to be elucidated. Here we report host spleen m6A epitranscriptome landscapes induced by different strains of the malaria parasite Plasmodium yoelii. We found that malaria parasite infection dramatically changes host spleen m6A mRNA modification and gene expression. Additionally, malaria parasite infection reprograms host immune response pathways by regulating the m6A modification enzymes. Collectively, our study is the first characterization of host spleen m6A methylome triggered by malaria parasite infections, and our data identify m6A modifications as significant transcriptome-wide marks during host-parasite interactions. We demonstrate that host mRNA methylation machinery can sense and respond to malaria parasite infections, and provide new insights into epitranscriptomic mechanisms underlying parasite-induced pathogenesis.

Time-resolved transcriptomes reveal diverse B cell fate trajectories in the early response to Epstein-Barr virus infection

Epstein-Barr virus infection of B lymphocytes elicits diverse host responses via well-adapted transcriptional control dynamics. Consequently, this host-pathogen interaction provides a powerful system to explore fundamental processes leading to consensus fate decisions. Here, we use single-cell transcriptomics to construct a genome-wide multistate model of B cell fates upon EBV infection. Additional single-cell data from human tonsils reveal correspondence of model states to analogous in vivo phenotypes within secondary lymphoid tissue, including an EBV+ analog of multipotent activated precursors that can yield early memory B cells. These resources yield exquisitely detailed perspectives of the transforming cellular landscape during an oncogenic viral infection that simulates antigen-induced B cell activation and differentiation. Thus, they support investigations of state-specific EBV-host dynamics, effector B cell fates, and lymphomagenesis. To demonstrate this potential, we identify EBV infection dynamics in FCRL4+/TBX21+ atypical memory B cells that are pathogenically associated with numerous immune disorders.

MARCH8 attenuates cGAS-mediated innate immune responses through ubiquitylation

Cyclic GMP-AMP synthase (cGAS) binds to microbial and self-DNA in the cytosol and synthesizes cyclic GMP-AMP (cGAMP), which activates stimulator of interferon genes (STING) and downstream mediators to elicit an innate immune response. Regulation of cGAS activity is essential for immune homeostasis. Here, we identified the E3 ubiquitin ligase MARCH8 (also known as MARCHF8, c-MIR, and RNF178) as a negative regulator of cGAS-mediated signaling. The immune response to double-stranded DNA was attenuated by overexpression of MARCH8 and enhanced by knockdown or knockout of MARCH8. MARCH8 interacted with the enzymatically active core of cGAS through its conserved RING-CH domain and catalyzed the lysine-63 (K63)-linked polyubiquitylation of cGAS at Lys⁴¹¹. This polyubiquitylation event inhibited the DNA binding ability of cGAS, impaired cGAMP production, and attenuated the downstream innate immune response. Furthermore, March8-deficient mice were less susceptible than their wild-type counterparts to herpes simplex virus 1 (HSV-1) infection. Together, our findings reveal a mechanism underlying the functional regulation of cGAS and the fine-tuning of the innate immune response.

The immune-specific E3 ubiquitin ligase MARCH1 is upregulated during HCMV infection to regulate iron levels

Human cytomegalovirus (HCMV) modulates numerous cellular pathways to facilitate infection. Iron is essential to many cellular processes and is often incorporated into proteins and enzymes involved in oxidative phosphorylation and DNA synthesis and repair, among others. Despite its prominent role in the cell, little is known about the regulation of iron metabolism during HCMV infection. Herein, we observe modulation of the transferrin receptor (TfR) during infection and a corresponding change in the cellular labile iron pool. TfR and the iron pool are increased early during infection and then return to mock levels at the late stages of infection. We identified the cellular ubiquitin ligase MARCH1 as an important regulator of TfR. MARCH1 plays a proviral role during infection, as its knockdown leads to a decrease in infectious titers. Knockdown of MARCH1 also leads to an increase in ROS, lipid peroxidation and mitochondrial dysfunction. Inhibiting an early increase in TfR expression during infection also decreases virus production. These findings indicate the importance of tightly regulating iron metabolism during HCMV infection to facilitate efficient virus production. Importance Iron is essential for cells, playing important roles in energy generation, DNA replication, and gene expression. During infection, HCMV alters many cellular processes to aid its replication. We found that iron levels are tightly regulated during infection and that dysregulation of iron levels alters the ability to produce infectious virions. We also found that HCMV inactivates many of the cellular safeguards put in place to deal with excess iron. Thus, infected cells become more susceptible to variations in iron levels, which could be exploited as a therapeutic strategy for dealing with HCMV infections.

E3 ubiquitin ligase RNF123-deficient mice exhibit reduced parasitemia and mortality in rodent malaria (Plasmodium yoelii 17XL) infection

Increased levels of several human ubiquitin ligases, including ring finger protein 123 (RNF123), in red blood cells with Plasmodium falciparum infection, have been reported. RNF123 is an E3 ubiquitin ligase that is highly expressed in erythroid cells. However, the function of the RNF123 gene and the relationship between the RNF123 gene and malarial parasite has not been clarified in vivo. In this study, we generated RNF123-deficient mice using the CRISPR/Cas9 system, and analyzed malaria susceptibility and erythrocyte morphology. The levels of parasitemia 5 days post-infection and mortality 21 days post-infection with the lethal type of rodent malaria (Plasmodium yoelii 17XL) in RNF123-deficient mice was significantly lower than that in wild-type mice. In contrast, red blood cell morphology in RNF123-deficient mice was almost normal. These results suggest that erythrocytic RNF123 plays a role in susceptibility to rodent malaria infection, but does not play a role in erythrocyte morphology.

Search for Selection Signatures Related to Trypanosomosis Tolerance in African Goats

Livestock is heavily affected by trypanosomosis in Africa. Through strong selective pressure, several African indigenous breeds of cattle and small ruminants have acquired varying degrees of tolerance against this disease. In this study, we combined LFMM and PCAdapt for analyzing two datasets of goats from West-Central Africa and East Africa, respectively, both comprising breeds with different assumed levels of trypanotolerance. The objectives were (i) to identify molecular signatures of selection related to trypanotolerance; and (ii) to guide an optimal sampling for subsequent studies. From 33 identified signatures, 18 had been detected previously in the literature as being mainly associated with climatic adaptations. The most plausible signatures of trypanotolerance indicate the genes DIS3L2, COPS7B, PD5A, UBE2K, and UBR1. The last gene is of particular interest since previous literature has already identified E3-ubiquitin ligases as playing a decisive role in the immune response. For following-up on these findings, the West-Central African area appears particularly relevant because of (i) a clear parasitic load gradient related to a humidity gradient, and (ii) still restricted admixture levels between goat breeds. This study illustrates the importance of protecting local breeds, which have retained unique allelic combinations conferring their remarkable adaptations.

Accelerator or Brake: Immune Regulators in Malaria

Malaria is a life-threatening infectious disease, affecting over 250 million individuals worldwide each year, eradicating malaria has been one of the greatest challenges to public health for a century. Growing resistance to anti-parasitic therapies and lack of effective vaccines are major contributing factors in controlling this disease. However, the incomplete understanding of parasite interactions with host anti-malaria immunity hinders vaccine development efforts to date. Recent studies have been unveiling the complexity of immune responses and regulators against Plasmodium infection. Here, we summarize our current understanding of host immune responses against Plasmodium-derived components infection and mainly focus on the various regulatory mechanisms mediated by recent identified immune regulators orchestrating anti-malaria immunity.

Type I Interferons and Malaria: A Double-Edge Sword Against a Complex Parasitic Disease

Type I interferons (IFN-Is) are important cytokines playing critical roles in various infections, autoimmune diseases, and cancer. Studies have also shown that IFN-Is exhibit 'conflicting' roles in malaria parasite infections. Malaria parasites have a complex life cycle with multiple developing stages in two hosts. Both the liver and blood stages of malaria parasites in a vertebrate host stimulate IFN-I responses. IFN-Is have been shown to inhibit liver and blood stage development, to suppress T cell activation and adaptive immune response, and to promote production of proinflammatory cytokines and chemokines in animal models. Different parasite species or strains trigger distinct IFN-I responses. For example, a Plasmodium yoelii strain can stimulate a strong IFN-I response during early infection, whereas its isogenetic strain does not. Host genetic background also greatly influences IFN-I production during malaria infections. Consequently, the effects of IFN-Is on parasitemia and disease symptoms are highly variable depending on the combination of parasite and host species or strains. Toll-like receptor (TLR) 7, TLR9, melanoma differentiation-associated protein 5 (MDA5), and cyclic GMP-AMP synthase (cGAS) coupled with stimulator of interferon genes (STING) are the major receptors for recognizing parasite nucleic acids (RNA/DNA) to trigger IFN-I responses. IFN-I levels in vivo are tightly regulated, and various novel molecules have been identified to regulate IFN-I responses during malaria infections. Here we review the major findings and progress in ligand recognition, signaling pathways, functions, and regulation of IFN-I responses during malaria infections.

Host-Malaria Parasite Interactions and Impacts on Mutual Evolution

Malaria is the most deadly parasitic disease, affecting hundreds of millions of people worldwide. Malaria parasites have been associated with their hosts for millions of years. During the long history of host-parasite co-evolution, both parasites and hosts have applied pressure on each other through complex host-parasite molecular interactions. Whereas the hosts activate various immune mechanisms to remove parasites during an infection, the parasites attempt to evade host immunity by diversifying their genome and switching expression of targets of the host immune system. Human intervention to control the disease such as antimalarial drugs and vaccination can greatly alter parasite population dynamics and evolution, particularly the massive applications of antimalarial drugs in recent human history. Vaccination is likely the best method to prevent the disease; however, a partially protective vaccine may have unwanted consequences that require further investigation. Studies of host-parasite interactions and co-evolution will provide important information for designing safe and effective vaccines and for preventing drug resistance. In this essay, we will discuss some interesting molecules involved in host-parasite interactions, including important parasite antigens. We also discuss subjects relevant to drug and vaccine development and some approaches for studying host-parasite interactions.