Biology subjects

Coscoy, L.

Publications and source records attributed to Coscoy, L..

9 recordsLinked to original sources

bioRxiv2024

The SP140-RESIST pathway regulates interferon mRNA stability and antiviral immunity

Type I interferons (IFN-Is) are essential for antiviral immunity but must be tightly regulated1-3. The conserved transcriptional repressor SP140 inhibits interferon beta (Ifnb1) expression via an unknown mechanism4,5. Here we report that SP140 does not directly repress Ifnb1 transcription. Instead, SP140 negatively regulates Ifnb1 mRNA stability by directly repressing the expression of a previously uncharacterized regulator we call RESIST (REgulated Stimulator of Interferon via Stabilization of Transcript, previously annotated as Annexin-2 Receptor). RESIST promotes Ifnb1 mRNA stability by counteracting Ifnb1 mRNA destabilization mediated by the Tristetraprolin (TTP) family of RNA-binding proteins and the CCR4-NOT deadenylase complex. SP140 localizes within nuclear bodies, punctate structures that play important roles in silencing DNA virus gene expression in the nucleus4. Consistent with this observation, we found that SP140 inhibits replication of the gammaherpesvirus MHV68. The antiviral activity of SP140 was independent of its ability to regulate Ifnb1. Our results establish dual antiviral and interferon regulatory functions for SP140. We propose that SP140 and RESIST participate in antiviral effector-triggered immunity6,7.

immunology↗

bioRxiv2022

SARS-CoV-2 Envelope-mediated Golgi pH dysregulation interferes with ERAAP retention in cells

Endoplasmic reticulum (ER) aminopeptidase associated with antigen processing (ERAAP) trims peptide precursors in the ER for presentation by major histocompatibility (MHC)-I molecules to surveying CD8+ T-cells. This function allows ERAAP to regulate the nature and quality of the peptide repertoire and, accordingly, the resulting immune responses. We recently showed that infection with murine cytomegalovirus leads to a dramatic loss of ERAAP levels in infected cells. In mice, this loss is associated with the activation of QFL T-cells, a subset of T-cells that monitor ERAAP integrity and eliminate cells experiencing ERAAP dysfunction. In this study, we aimed to identify host factors that regulate ERAAP expression level and determine whether these could be manipulated during viral infections. We performed a CRISPR knockout screen and identified ERp44 as a factor promoting ERAAP retention in the ER. ERp44s interaction with ERAAP is dependent on the pH gradient between the ER and Golgi. We hypothesized that viruses that disrupt the pH of the secretory pathway interfere with ERAAP retention. Here, we demonstrate that expression of the Envelope (E) protein from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) leads to Golgi pH neutralization and consequently decrease of ERAAP intracellular levels. Furthermore, SARS-CoV-2-induced ERAAP loss correlates with its release into the extracellular environment. ERAAPs reliance on ERp44 and a functioning ER/Golgi pH gradient for proper localization and function led us to propose that ERAAP serves as a sensor of disturbances in the secretory pathway during infection and disease.

cell biology↗

bioRxiv2022

Murine cytomegalovirus downregulates ERAAP and induces an unconventional T cell response to self

The endoplasmic reticulum aminopeptidase associated with antigen presentation (ERAAP) plays a crucial role in shaping the peptide-MHC I repertoire and maintaining immune surveillance. While murine cytomegalovirus (MCMV) has multiple strategies for manipulating the antigen processing pathway to evade immune responses, the host has also developed ways to counter viral immune evasion. In this study, we found that MCMV modulates ERAAP and induces an IFN-{gamma} producing CD8+ T cell effector response that targets uninfected ERAAP deficient cells. We also observed that ERAAP downregulation during infection led to presentation of the self-peptide FL9 on non-classical Qa-1b, thereby eliciting Qa-1b restricted QFL T cells to proliferate in the liver and spleen of infected mice. QFL T cells upregulated effector markers upon MCMV infection and were sufficient to reduce viral load after transfer to immunodeficient mice. Our study highlights the consequences of ERAAP dysfunction during viral infection and provides potential targets for antiviral therapies.

immunology↗

bioRxiv2022

Fam49b dampens TCR signal strength to regulate survival of positively selected thymocytes

The fate of developing T cells is determined by the strength of T cell receptor (TCR) signal they receive in the thymus. This process is finely regulated through tuning of positive and negative regulators in thymocytes. The Family with sequence similarity 49 member B (Fam49b) protein is a newly discovered negative regulator of TCR signaling that has been shown to suppress Rac-1 activity in vitro in cultured T cell lines. However, the contribution of Fam49b to thymic development of T cells is unknown. To investigate this important issue, we generated a novel mouse line deficient in Fam49b (Fam49b-KO). We observed that Fam49b-KO double positive (DP) thymocytes underwent excessive negative selection, whereas the positive selection stage was unaffected. This altered development process resulted in significant reductions in CD4 and CD8 single positive thymocytes as well as peripheral T cells. Interestingly, a large proportion of the TCR{gamma}{delta}+ and CD8+TCR{beta}+ gut intraepithelial T lymphocytes were absent in Fam49b-KO mice. Our results demonstrate that Fam49b dampens thymocytes TCR signaling in order to escape negative selection during development, uncovering the function of Fam49b as a critical regulator of selection process to ensure normal thymocyte development.

immunology↗

bioRxiv2020

Fetal innate immunity contributes to the induction of atypical behaviors in a mouse model of maternal immune activation

Maternal immune activation (MIA) increases likelihood of altered neurodevelopmental outcomes. Maternal cytokines are proposed to affect fetal brain development in mice; however, the contribution of fetal immunity to neurodevelopmental disorders is largely unexplored. Here, we show that MIA mediated by Toll-like receptor 3 (TLR3), but not other TLRs, induces a specific set of behavioral phenotypes including decreased sociability and increased restricted repetitive behavior in offspring. Accordingly, these behavioral phenotypes were absent when offspring were deficient for Trif, the downstream adapter molecule of TLR3. Using single-cell RNA sequencing, we identified clusters of border-associated macrophages that were significantly enriched in the fetal brain following TLR3-MIA, and these clusters were diminished in Trif-/- fetal brains.Moreover, we found that triggering TLR3-TRIF in offspring can occur through transplacental viral infection, resulting in altered behavioral phenotypes. Collectively, our data indicate that fetal innate immunity contributes to MIA-induced atypical behaviors in mice.

neuroscience↗

bioRxiv2020

Comparative analysis of macrophage post-translational modifications during intracellular bacterial pathogen infection

Macrophages activate robust antimicrobial functions upon engulfing virulent bacteria, yet a wide array of pathogens paradoxically thrive within these innate immune cells. To probe the pathogen-macrophage interface, we used proteomics to comprehensively quantify changes in post-translational modifications (PTMs) of host proteins during infection with three evolutionarily diverse intracellular pathogens: Mycobacterium tuberculosis, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes. Comparing global phosphorylation and ubiquitylation patterns identified extensive reprogramming of cellular pathways during infection, with ubiquitylation patterns revealing unique pathogen-specific molecular response signatures undetectable by transcriptional profiling. Differential PTM changes during infection with attenuated M. tuberculosis cells lacking the ESX-1 virulence determinant revealed extensive modification of phagosome dynamics and antiviral type I interferon activation. We found that M. tuberculosis-mediated activation of the antiviral OASL1-IRF7 pathway promotes bacterial replication, uncovering a new mechanism of virus-bacterial synergy. Our data reveals remarkable specificity in innate cellular responses to complex stimuli and provides a resource for deeper understanding of host-pathogen interactions.

microbiology↗

bioRxiv2019

Heparan sulfate expression on B cells modulates IgM expression in aged mice and steady-state plasma cells

Heparan sulfate (HS) modulates many cellular processes including adhesion, motility, ligand-receptor interaction, and proliferation. We have previously reported that murine B cells strongly upregulate cell surface HS upon exposure to type I interferon, TLR-ligands, or B cell receptor stimulation. To investigate the role of HS on B cells in vivo, we utilized EXT1lox/lox CD19-Cre conditional KO mice, which are incapable of synthesizing HS in B cells. We found that suppressing HS expression on B cells has no overt effect in B cell development, localization, or motility. However, we did observe that EXT1 conditional KO mice have decreased poly-reactive IgM in naive aged mice relative to littermate control mice. Despite this decrease in poly-reactive IgM, EXT1 conditional KO mice mounted a normal B cell response to both model antigens and influenza infection. We also observed decreased plasma cells in EXT1 conditional KO mice after influenza infection. Although EXT1 conditional KO mice have decreased plasma cells, these mice still had comparable numbers of influenza-specific antibody secreting cells to littermate control mice. The findings presented here suggest that HS expression on B cells does not play a major role in B cell development or overall B cell function but instead might be involved in fine-tuning B-cell responses.

immunology↗

bioRxiv2018

An Integrin-Independent Kaposi’s Sarcoma-Associated Herpesvirus Infection Mechanism

Host receptor usage by KSHV has been best studied using primary microvascular endothelial and fibroblast cells, although the virus infects a wide variety of cell types in culture and in natural infections. In these two infection models, KSHV adheres to the cell though heparan sulfate (HS) binding, then interacts with a complex of EphA2, xct, and integrins 3{beta}1, V{beta}3, V{beta}5 to catalyze viral entry. We dissected this receptor complex at the genetic level with CRISPR-Cas9 to precisely determine receptor usage in two epithelial cell lines. Surprisingly, we discovered an infection mechanism that requires HS and EphA2 but is independent of V- and {beta}1-family integrin expression. Furthermore, infection appears to be independent of the EphA2 intracellular domain. We also demonstrated while two other endogenous Eph receptors were dispensable for KSHV infection, transduced EphA4 and EphA5 significantly enhanced infection of cells lacking EphA2.\n\nIMPORTANCEOur data reveals an integrin-independent route of KSHV infection and suggests that multiple Eph receptors besides EphA2 can promote and regulate infection. Since integrins and Eph receptors are large protein families with diverse expression patterns across cells and tissues, we propose that KSHV may engage with several proteins from both families in different combinations to negotiate successful entry into diverse cell types.

microbiology↗

bioRxiv2017

An Mtb-Human Protein-Protein Interaction Map Reveals that Bacterial LpqN Antagonizes CBL, a Host Ubiquitin Ligase that Regulates the Balance Between Anti-Viral and Anti-Bacterial Responses

Although macrophages are armed with potent anti-bacterial functions, Mycobacterium tuberculosis (Mtb) replicates inside these innate immune cells. Determinants of macrophage-intrinsic bacterial control, and the Mtb strategies to overcome them are poorly understood. To further study these processes, we used a systematic affinity tag purification mass spectrometry (AP-MS) approach to identify 187 Mtb-human protein-protein interactions (PPIs) involving 34 secreted Mtb proteins. This interaction map revealed two new factors involved in Mtb pathogenesis - the secreted Mtb protein, LpqN, and its binding partner, the human ubiquitin ligase CBL. We discovered that an lpqN Mtb mutant is attenuated in macrophages, but growth is restored when CBL is removed. Conversely, Cbl-/- macrophages are resistant to viral infection, indicating that CBL regulates cell-intrinsic polarization between anti-bacterial and anti-viral immunity. Collectively, these findings illustrate the utility of this Mtb-human PPI map as a resource for developing a deeper understanding of the intricate interactions between Mtb and its host.

microbiology↗