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Biology subjects

Stanifer, M. L.

Publications and source records attributed to Stanifer, M. L..

16 recordsLinked to original sources

SEHI-PPI: An End-to-End Sampling-Enhanced Human-Influenza Protein-Protein Interaction Prediction Framework with Double-View Learning

Influenza continues to pose significant global health threats, hijacking host cellular machinery through protein-protein interactions (PPIs), which are fundamental to viral entry, replication, immune evasion, and transmission. Yet, our understanding of these host-virus PPIs remains incomplete due to the vast diversity of viral proteins, their rapid mutation rates, and the limited availability of experimentally validated interaction data. Additionally, existing computational methods often struggle due to the limited availability of high-quality samples and their inability to effectively model the complex nature of host-virus interactions. To address these challenges, we present SEHI-PPI, an end-to-end framework for human-influenza PPI prediction. SEHI-PPI integrates a double-view deep learning architecture that captures both global and local sequence features, coupled with a novel adaptive negative sampling strategy to generate reliable and high-quality negative samples. Our method outperforms multiple benchmarks, including state-of-the-art large language models, achieving a superior performance in sensitivity (0.986) and AUROC (0.987). Notably, in a stringent test involving entirely unseen human and influenza protein families, SEHI-PPI maintains strong performance with an AUROC of 0.837. The model also demonstrates high generalizability across other human-virus PPI datasets, with an average sensitivity of 0.929 and AUROC of 0.928. Furthermore, AlphaFold3-guided case studies reveal that viral proteins predicted to target the same human protein cluster together structurally and functionally, underscoring the biological relevance of our predictions. These discoveries demonstrate the reliability of our SEHI-PPI framework in uncovering biologically meaningful host-virus interactions and potential therapeutic targets.

bioinformatics↗

Population context drives cell-to-cell variability in interferon response in epithelial cells

Isogenic cells respond in a heterogeneous manner to interferon. Using a micropatterning approach combined with high-content imaging and spatial analyses, we characterized how the population context (position of a cell with respect to the neighboring cells) of human intestinal epithelial cells affects single cell response to interferons. We identified that cells at the edge of a cellular colony are significantly more responsive than cells embedded within this colony. We determined that this spatial heterogeneity in IFN response was the result of the polarized basolateral distribution of the IFN receptors making cells located in the center of a cellular colony not responsive to ectopic IFN stimulation. We could demonstrate that this population context driven cell-to-cell variability influences the outcome of viral infection as cells embedded in a cellular colony are not protected by interferons and therefore more susceptible to infection. Our data highlights that the behavior of individual isolated cells does not directly translate to their behavior in a population, placing the population context as a key driver of cell-to-cell heterogeneity in IFN response.

immunology↗

USP22 controls type III interferon signaling and SARS-CoV-2 infection through activation of STING

Pattern recognition receptors (PRRs) and interferons (IFNs) serve as essential antiviral defense against SARS-CoV-2, the causative agent of the COVID-19 pandemic. Type III IFN (IFN-{lambda}) exhibit cell-type specific and long-lasting functions in autoinflammation, tumorigenesis and antiviral defense. Here, we identify the deubiquitinating enzyme USP22 as central regulator of basal IFN-{lambda} secretion and SARS-CoV-2 infections in native human intestinal epithelial cells (hIECs). USP22-deficient hIECs strongly upregulate genes involved in IFN signaling and viral defense, including numerous IFN-stimulated genes (ISGs), with increased secretion of IFN-{lambda} and enhanced STAT1 signaling, even in the absence of exogenous IFNs or viral infection. Interestingly, USP22 controls basal and 23-cGAMP-induced STING activation and loss of STING reversed STAT activation and ISG and IFN-{lambda} expression. Intriguingly, USP22-deficient hIECs are protected against SARS-CoV-2 infection, viral replication and the formation of de novo infectious particles, in a STING-dependent manner. These findings reveal USP22 as central host regulator of STING and type III IFN signaling, with important implications for SARS-CoV-2 infection and antiviral defense.

cell biology↗

Conserved induction of distinct antiviral signalling kinetics by primate interferon lambda 4 proteins

Interferon lambdas (IFN{lambda}) (also known as type III IFNs) are critical cytokines that combat infection predominantly at barrier tissues, such as the lung, liver and gastrointestinal tract. Humans have four IFN{lambda}s (1-4) where IFN{lambda}1-3 show [~]80-95% homology and IFN{lambda}4 is the most divergent displaying only [~]30% sequence identity. Variants in IFN{lambda}4 in humans are associated with the outcome of infection, such as with hepatitis C virus. However, how IFN{lambda}4 variants impact cytokine signalling in other tissues and how well this is conserved is largely unknown. In this study we address whether differences in antiviral signalling exist between IFN{lambda}4 variants in human hepatocyte and intestinal cells, comparing them to IFN{lambda}3. We demonstrate that compared to IFN{lambda}3, wild-type human IFN{lambda}4 induces a signalling response with distinct magnitudes and kinetics, which is modified by naturally-occurring variants P70S and K154E in both cell types. IFN{lambda}4s distinct antiviral response was more rapid yet transient compared to IFN{lambda}1 and 3. Additionally, divergent antiviral kinetics were also observed using non-human primate IFN{lambda}s and cell lines. Furthermore, an IFN{lambda}4-like receptor-interacting interface failed to alter IFN{lambda}1s kinetics. Together our data provide further evidence that major functional differences exist within the IFN{lambda} gene family. These results highlight the possible tissue specialisation of IFN{lambda}s and encourage further investigation of the divergent, non-redundant activities of IFN{lambda}4 and other IFN{lambda}s. Contribution to the FieldViral infections remain major causes of death and disease in humans and other animals. Interferons (IFNs) are a diverse group of host signalling proteins that can induce a potent antiviral state in cells and are intimately involved in the outcome of infection. Genetic variants within one IFN (interferon lambda 4, IFN{lambda}4) are associated with the outcome of hepatitis C infection in humans. However, how IFN{lambda}4 functions - and how natural variants affect its activity - remains poorly understood. Comparing how the antiviral activity changes over time following stimulation with different IFN{lambda}s, we identified that IFN{lambda}4 induces a more rapid antiviral state compared to other IFN{lambda}s in liver and intestinal cells. Importantly, this response was conserved within human variants and between humans and non-human primates (chimpanzee and Rhesus macaque). Our results shed light on the unique functions of the divergent IFN{lambda}4 protein.

immunology↗

A diabetic milieu increases cellular susceptibility to SARS-CoV-2 infections in engineered human kidney organoids and diabetic patients

SARS-CoV-2 infections lead to a high risk of hospitalization and mortality in diabetic patients. Why diabetic individuals are more prone to develop severe COVID-19 remains unclear. Here, we established a novel human kidney organoid model that mimics early hallmarks of diabetic nephropathy. High oscillatory glucose exposure resulted in metabolic changes, expansion of extracellular membrane components, gene expression changes determined by scRNAseq, and marked upregulation of angiotensin-converting enzyme 2 (ACE2). Upon SARS-CoV-2 infection, hyperglycemic conditions lead to markedly higher viral loads in kidney organoids compared to normoglycemia. Genetic deletion of ACE2, but not of the candidate receptor BSG/CD147, in kidney organoids demonstrated the essential role of ACE2 in SARS-CoV-2 infections and completely prevented SARS-CoV-2 infection in the diabetogenic microenvironment. These data introduce a novel organoid model for diabetic kidney disease and show that diabetic-induced ACE2 licenses the diabetic kidney to enhanced SARS-CoV-2 replication.

cell biology↗

Reprogramming of the intestinal epithelial-immune cell interactome during SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents an unprecedented worldwide health problem. Although the primary site of infection is the lung, growing evidence points towards a crucial role of the intestinal epithelium. Yet, the exact effects of viral infection and the role of intestinal epithelial-immune cell interactions in mediating the inflammatory response are not known. In this work, we apply network biology approaches to single-cell RNA-seq data from SARS-CoV-2 infected human ileal and colonic organoids to investigate how altered intracellular pathways upon infection in intestinal enterocytes leads to modified epithelial-immune crosstalk. We point out specific epithelial-immune interactions which could help SARS-CoV-2 evade the immune response. By integrating our data with existing experimental data, we provide a set of epithelial ligands likely to drive the inflammatory response upon infection. Our integrated analysis of intra- and inter-cellular molecular networks contribute to finding potential drug targets, and suggest using existing anti-inflammatory therapies in the gut as promising drug repurposing strategies against COVID-19.

bioinformatics↗

Network-based identification and pharmacological targeting of host cell master regulators induced by SARS-CoV-2 infection

Precise characterization and targeting of host cell transcriptional machinery hijacked by SARS-CoV-2 remains challenging. To identify therapeutically targetable mechanisms that are critical for SARS-CoV-2 infection, here we elucidated the Master Regulator (MR) proteins representing mechanistic determinants of the gene expression signature induced by SARS-CoV-2. The analysis revealed coordinated inactivation of MR-proteins linked to regulatory programs potentiating efficiency of viral replication (detrimental host MR-signature) and activation of MR-proteins governing innate immune response programs (beneficial MR-signature). To identify MR-inverting compounds capable of rescuing activity of inactivated host MR-proteins, with-out adversely affecting the beneficial MR-signature, we developed the ViroTreat algorithm. Overall, >80% of drugs predicted to be effective by this methodology induced significant reduction of SARS-CoV-2 infection, without affecting cell viability. ViroTreat is fully generalizable and can be extended to identify drugs targeting the host cell-based MR signatures induced by virtually any pathogen.

microbiology↗

Host Cell Proteases Drive Early or Late SARS-CoV-2 Penetration

SARS-CoV-2 is a newly emerged coronavirus (CoV) that spread through human populations worldwide in early 2020. CoVs rely on host cell proteases for activation and infection. The trypsin-like protease TMPRSS2 at the cell surface, cathepsin L in endolysosomes, and furin in the Golgi have all been implicated in the SARS-CoV-2 proteolytic processing. Whether SARS-CoV-2 depends on endocytosis internalization and vacuolar acidification for infectious entry remains unclear. Here, we examined the dynamics of SARS-CoV-2 activation during the cell entry process in tissue culture. Using four cell lines representative of lung, colon, and kidney epithelial tissues, we found that TMPRSS2 determines the SARS-CoV-2 entry pathways. In TMPRSS2-positive cells, infection was sensitive to aprotinin, a TMPRSS2 inhibitor, but not to SB412515, a drug that impairs cathepsin L. Infectious penetration was marginally dependent on endosomal acidification, and the virus passed the protease-sensitive step within 10 min. In a marked contrast, in TMPRSS2-negative cells cathepsin L and low pH were required for SARS-CoV-2 entry. The cathepsin L-activated penetration occurred within 40-60 min after internalization and required intact endolysosomal functions. Importantly, pre-activation of the virus allowed it to bypass the need for endosomal acidification for viral fusion and productive entry. Overall, our results indicate that SARS-CoV-2 shares with other CoVs a strategy of differential use of host cell proteases for activation and infectious penetration. This study also highlights the importance of TMPRSS2 in dictating the entry pathway used by SARS-CoV-2. SignificancePreventing SARS-CoV-2 spread requires approaches affecting early virus-host cell interactions before the virus enters and infects target cells. Host cell proteases are critical for coronavirus activation and infectious entry. Here, we reconcile apparent contradictory observations from recent reports on endosomal acidification and the role of furin, TMPRSS2, and cathepsin L in the productive entry and fusion process of SARS-CoV-2. Investigating authentic virus in various cell types, we demonstrated that SARS-CoV-2 developed the ability to use different entry pathways, depending on the proteases expressed by the target cell. Our results have strong implications for future research on the apparent broad tropism of the virus in vivo. This study also provides a handle to develop novel antiviral strategies aiming to block virus entry, as illustrated with the several drugs that we identified to prevent SARS-CoV-2 infection, some with low IC50.

microbiology↗

Single-cell analyses reveal SARS-CoV-2 interference with intrinsic immune response in the human gut

ObjectiveExacerbated pro-inflammatory immune response contributes to COVID-19 pathology. Despite the evidence about SARS-CoV-2 infecting the human gut, little is known about the importance of the enteric phase of SARS-CoV-2 for the viral lifecycle and for the development of COVID-19-associated pathologies. Similarly, it remains unknown whether the innate immune response triggered in this organ to combat viral infection is similar or distinct compared to the one triggered in other organs. DesignWe exploited human ileum- and colon-derived organoids as a non-transformed culture model supporting SARS-CoV-2 infection. We characterized the replication kinetics of SARS-CoV-2 in intestinal epithelial cells and correlated the expression of the viral receptor ACE2 with infection. We performed conventional and targeted single-cell transcriptomics and multiplex single-molecule RNA fluorescence in situ hybridization and used IFN-reporter bioassays to characterize the response of primary human intestinal epithelial cells to SARS-CoV-2 infection. ResultsWe identified a subpopulation of enterocytes as the prime target of SARS-CoV-2. We found the lack of positive correlation between susceptibility to infection and the expression of ACE2 and revealed that SARS-CoV-2 downregulates ACE2 expression upon infection. Infected cells activated strong proinflammatory programs and produced interferon, while expression of interferon-stimulated genes was limited to bystander cells due to SARS-CoV-2 suppressing the autocrine action of interferon in infected cells. ConclusionOur findings reveal that SARS-CoV-2 curtails the immune response in primary human intestinal epithelial cells to promote its replication and spread and this highlights the gut as a proinflammatory reservoir that should be considered to fully understand SARS-CoV-2 pathogenesis. Significance of the studyWhat is already known about this subject? O_LICOVID-19 patients have gastrointestinal symptoms which likely correlates with SARS-CoV-2 infection of the intestinal epithelium C_LIO_LISARS-CoV-2 replicates in human intestinal epithelial cells. C_LIO_LIIntestinal organoids are a good model to study SARS-CoV-2 infection of the gastrointestinal tract C_LIO_LIThere is a limited interferon response in human lung epithelial cells upon SARS-CoV-2 infection. C_LI What are the new findings? O_LIA specific subpopulation of enterocytes are the prime targets of SARS-CoV-2 infection of the human gut. C_LIO_LIThere is a lack of correlation between ACE2 expression and susceptibility to SARS-CoV-2 infection. SARS-CoV-2 downregulates ACE2 expression upon infection. C_LIO_LIHuman intestinal epithelium cells produce interferon upon SARS-CoV-2 infection. C_LIO_LIInterferon acts in a paracrine manner to induce interferon stimulated genes that control viral infection only in bystander cells. C_LIO_LISARS-CoV-2 actively blocks interferon signaling in infected cells. C_LI How might it impact on clinical practice in the foreseeable future? O_LIThe absence of correlation between ACE2 levels and susceptibility suggest that medications influencing ACE2 levels (e.g. high blood pressure drugs) will not make patients more susceptible to SARS-CoV-2 infection. C_LIO_LIThe restricted cell tropism and the distinct immune response mounted by the GI tract, suggests that specific cellular restriction/replication factors and organ specific intrinsic innate immune pathways can represent unique therapeutic targets to treat COVD-19 patients by considering which organ is most infected/impacted by SARS-CoV-2. C_LIO_LIThe strong pro-inflammatory signal mounted by the intestinal epithelium can fuel the systemic inflammation observed in COVID-19 patients and is likely participating in the lung specific pathology. C_LI

immunology↗

Single-cell transcriptomics reveals immune response of intestinal cell types to viral infection

Human intestinal epithelial cells form a primary barrier protecting us from pathogens, yet only limited knowledge is available about individual contribution of each cell type to mounting an immune response against infection. Here, we developed a pipeline combining single-cell RNA-Seq and highly-multiplex RNA imaging and applied it to human intestinal organoids infected with human astrovirus, a model human enteric virus. We found that interferon controls the infection and that astrovirus infects all major cell types and lineages with a preferential infection of proliferating cells. Intriguingly, each intestinal epithelial cell lineage has a unique basal expression of interferon-stimulated genes and, upon astrovirus infection, undergoes an antiviral transcriptional reprogramming by upregulating distinct sets of interferon-stimulated genes. These findings suggest that in the human intestinal epithelium, each cell lineage plays a unique role in resolving virus infection. Our pipeline can be applicable to other organoids and viruses, opening new avenues to unravel roles of individual cell types in viral pathogenesis.

systems biology↗

Interferons and viruses induce a novel primate-specific isoform dACE2 and not the SARS-CoV-2 receptor ACE2

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes COVID-19, utilizes angiotensin-converting enzyme 2 (ACE2) for entry into target cells. ACE2 has been proposed as an interferon-stimulated gene (ISG). Thus, interferon-induced variability in ACE2 expression levels could be important for susceptibility to COVID-19 or its outcomes. Here, we report the discovery of a novel, primate-specific isoform of ACE2, which we designate as deltaACE2 (dACE2). We demonstrate that dACE2, but not ACE2, is an ISG. In vitro, dACE2, which lacks 356 N-terminal amino acids, was non-functional in binding the SARS-CoV-2 spike protein and as a carboxypeptidase. Our results reconcile current knowledge on ACE2 expression and suggest that the ISG-type induction of dACE2 in IFN-high conditions created by treatments, inflammatory tumor microenvironment, or viral co-infections is unlikely to affect the cellular entry of SARS-CoV-2 and promote infection.

genetics↗

SARS-CoV-2 structure and replication characterized by in situ cryo-electron tomography

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the COVID19 pandemic, is a highly pathogenic {beta}-coronavirus. As other coronaviruses, SARS-CoV-2 is enveloped, replicates in the cytoplasm and assembles at intracellular membranes. Here, we structurally characterize the viral replication compartment and report critical insights into the budding mechanism of the virus, and the structure of extracellular virions close to their native state by in situ cryo-electron tomography and subtomogram averaging. We directly visualized RNA filaments inside the double membrane vesicles, compartments associated with viral replication. The RNA filaments show a diameter consistent with double-stranded RNA and frequent branching likely representing RNA secondary structures. We found that assembled S trimers in lumenal cisternae do not alone induce membrane bending but laterally reorganize on the envelope during virion assembly. The viral ribonucleoprotein complexes (vRNPs) are accumulated at the curved membrane characteristic for budding sites suggesting that vRNP recruitment is enhanced by membrane curvature. Subtomogram averaging shows that vRNPs are distinct cylindrical assemblies. We propose that the genome is packaged around multiple separate vRNP complexes, thereby allowing incorporation of the unusually large coronavirus genome into the virion while maintaining high steric flexibility between the vRNPs.

microbiology↗

Critical role of type III interferon in controlling SARS-CoV-2 infection, replication and spread in primary human intestinal epithelial cells

SARS-CoV-2 is an unprecedented worldwide health problem that requires concerted and global approaches to better understand the virus in order to develop novel therapeutic approaches to stop the COVID-19 pandemic and to better prepare against potential future emergence of novel pandemic viruses. Although SARS-CoV-2 primarily targets cells of the lung epithelium causing respiratory infection and pathologies, there is growing evidence that the intestinal epithelium is also infected. However, the importance of the enteric phase of SARS-CoV-2 for virus-induced pathologies, spreading and prognosis remains unknown. Here, using both colon-derived cell lines and primary non-transformed colon organoids, we engage in the first comprehensive analysis of SARS-CoV-2 lifecycle in human intestinal epithelial cells. Our results demonstrate that human intestinal epithelial cells fully support SARS-CoV-2 infection, replication and production of infectious de-novo virus particles. Importantly, we identified intestinal epithelial cells as the best culture model to propagate SARS-CoV-2. We found that viral infection elicited an extremely robust intrinsic immune response where, interestingly, type III interferon mediated response was significantly more efficient at controlling SARS-CoV-2 replication and spread compared to type I interferon. Taken together, our data demonstrate that human intestinal epithelial cells are a productive site of SARS-CoV-2 replication and suggest that the enteric phase of SARS-CoV-2 may participate in the pathologies observed in COVID-19 patients by contributing in increasing patient viremia and by fueling an exacerbated cytokine response.

microbiology↗

Correlative cryo-structured illumination fluorescence microscopy and soft X-ray tomography elucidates reovirus intracellular release pathway

Imaging of biological matter across resolution scales presents the challenge of preserving the direct and unambiguous correlation of subject features from the macroscopic to the microscopic level. We present here a correlative imaging platform developed specifically for imaging cells in 3D, under cryogenic conditions. Rapid cryo-preservation of biological specimens is the current gold standard in sample preparation for ultrastructural analysis in X-ray imaging. However, cryogenic fluorescence localisation methods are by and large diffraction-limited and fail to deliver matching resolution. We addressed this technological gap by developing an integrated, user-friendly, platform for 3D correlative imaging of cells in cryo-preserved states using super-resolution structured illumination microscopy (SIM) in conjunction with soft X-ray tomography (SXT). The power of this new approach is demonstrated by studying the process of reovirus release from intracellular vesicles during the early stages of infection and identifying novel virus-induced structures.

cell biology↗

Hypoxic environment promotes barrier formation in human intestinal epithelial cells through regulation of miRNA-320a expression

Intestinal epithelial cells (IECs) are exposed to the low-oxygen environment present in the lumen of the gut. These hypoxic conditions are on one hand fundamental for the survival of the commensal microbiota, and on the other hand, favor the formation of a selective semipermeable barrier allowing IECs to transport essential nutrients/water while keeping the sterile internal compartments separated from the lumen containing commensals. The hypoxia-inducible factor (HIF) complex, which allows cells to respond and adapt to fluctuations in oxygen levels, has been described as a key regulator in maintaining IEC barrier function by regulating their tight junction integrity. In this study, we sought to better evaluate the mechanisms by which low oxygen conditions impact the barrier function of human IECs. By profiling miRNA expression in IECs under hypoxia, we identified miRNA-320a as a novel barrier formation regulator. Using pharmacological inhibitors and short hairpin RNA-mediated silencing we could demonstrate that expression of this miRNA was HIF-dependent. Importantly, using over-expression and knock-down approaches of miRNA-320a we could confirm its direct role in the regulation of barrier functions in human IECs. These results reveal an important link between miRNA expression and barrier integrity, providing a novel insight into mechanisms of hypoxia-driven epithelial homeostasis.

molecular biology↗

Differential induction of interferon stimulated genes between type I and type III interferons is independent of interferon receptor abundance

It is currently believed that type I and III interferons (IFNs) have redundant functions. However, the preferential distribution of type III IFN receptor on epithelial cells suggests functional differences at epithelial surfaces. Here, using human intestinal epithelial cells we could show that although both type I and type III IFNs confer an antiviral state to the cells, they do so with distinct kinetics. Type I IFN signaling is characterized by an acute strong induction of interferon stimulated genes (ISGs) and confers fast antiviral protection. On the contrary, the slow acting type III IFN mediated antiviral protection is characterized by a weaker induction of ISGs in a delayed manner compared to type I IFN. Moreover, while transcript profiling revealed that both IFNs induced a similar set of ISGs, their temporal expression strictly depended on the IFNs, thereby leading to unique antiviral environments. Using a combination of data-driven mathematical modeling and experimental validation, we addressed the molecular reason for this differential kinetic of ISG expression. We could demonstrate that these kinetic differences are intrinsic to each signaling pathway and not due to different expression levels of the corresponding IFN receptors. We report that type III IFN is specifically tailored to act in specific cell types not only due to the restriction of its receptor but also by providing target cells with a distinct antiviral environment compared to type I IFN. We propose that this specific environment is key at surfaces that are often challenged with the extracellular environment.\n\nAuthor summaryThe human intestinal tract plays two important roles in the body: first it is responsible for nutrient absorption and second it is the primary barrier which protects the human body from the outside environment. This complex tissue is constantly exposed to commensal bacteria and is often exposed to both bacterial and viral pathogens. To protect itself, the gut produces, among others, secreted agents called interferons which help to fight against pathogen attacks. There are several varieties (type I, II, and III) of interferons and our work aims at understanding how type I and III interferon act to protect human intestinal epithelial cells (hIECs) during viral infection. In this study, we confirmed that both interferons can protect hIECs against viral infection but with different kinetics. We determined that type I confer an antiviral state to hIECs faster than type III interferons. We uncovered that these differences were intrinsic to each pathway and not the result of differential abundance of the respective interferon receptors. The results of this study suggest that type III interferon may provide a different antiviral environment to the epithelium target cells which is likely critical for maintaining gut homeostasis. Our findings will also help us to design therapies to aid in controlling and eliminating viral infections of the gut.

immunology↗