Project description:Evolutionarily successful poxviruses presented effective and diverse strategies to circumvent or overcome host defense mechanisms. Poxviruses encode many immunoregulatory proteins to evade host immunity for a productive infection and unique means of inhibiting DNA-sensing dependent type 1 interferon (IFN-I) responses is anticipated due to the biology of its dsDNA genome in nature and an exclusive cytoplasmic life cycle. We found the key DNA sensing inhibition by poxvirus infection was dominant during the early stage of poxvirus infection independent from DNA replication. In an effort of identifying poxvirus novel means to subdue antiviral proinflammatory responses e.g., IFN-I response, we focused on the function of one early gene that is the known host range determinant from the highly conserved poxvirus host range C7L superfamily, myxoma virus (MYXV) M062. Host range factors are unique features of poxviruses that determine the species and cell type tropism. Almost all sequenced mammalian poxviruses retain at least one homologue of the poxvirus host range C7L superfamily. In MYXV, a rabbit specific poxvirus, the dominant and broad-spectrum host range determinant of the C7L superfamily is the M062R gene. M062R gene product is essential for MYXV infection in almost all cells tested from different mammalian species and specifically inhibits the function of host Sterile α Motif Domain-containing 9 (SAMD9), as M062R-null (ΔM062R) MYXV causes abortive infection in a SAMD9-dependend manner. In this study we investigated the immunostimulatory property of the ΔM062R. We found that the replication-defective ΔM062R infection activated host DNA sensing pathway in the cGAS dependent fashion and knocking down SAMD9 expression attenuated proinflammatory responses. Moreover, transcriptomic analyses showed a unique feature of host gene expression landscape that is different from dsDNA stimulated inflammatory state. This study built a link between the anti-neoplastic SAMD9 and the regulation of the innate immune responses.
Project description:A century ago, influenza A virus (IAV) infection caused the 1918 flu pandemic and killed an estimated 20-40 million people. Pandemic IAV outbreaks occur when strains from animal reservoirs acquire the ability to infect and spread among humans. The molecular details of this species barrier are incompletely understood. We combined metabolic pulse labeling and quantitative shotgun proteomics to globally monitor protein synthesis upon infection of human cells with a human- and a bird-adapted IAV strain. While production of host proteins was remarkably similar, we observed striking differences in the kinetics of viral protein synthesis over the course of infection. Most importantly, the matrix protein M1 was inefficiently produced by the bird-adapted strain at later stages. We show that impaired production of M1 from bird-adapted strains is caused by increased splicing of the M segment RNA to alternative isoforms. Experiments with reporter constructs and recombinant influenza viruses revealed that strain-specific M segment splicing is controlled by the 3’ splice site and functionally important for permissive infection. Independent in silico and biochemical evidence shows that avian-adapted M segments have evolved different conserved RNA structure features than human-adapted sequences. Thus, our data identifies M segment RNA splicing as a viral determinant of host range.
Project description:A century ago, influenza A virus (IAV) infection caused the 1918 flu pandemic and killed an estimated 20-40 million people. Pandemic IAV outbreaks occur when strains from animal reservoirs acquire the ability to infect and spread among humans. The molecular details of this species barrier are incompletely understood. We combined metabolic pulse labeling and quantitative shotgun proteomics to globally monitor protein synthesis upon infection of human cells with a human- and a bird-adapted IAV strain. While production of host proteins was remarkably similar, we observed striking differences in the kinetics of viral protein synthesis over the course of infection. Most importantly, the matrix protein M1 was inefficiently produced by the bird-adapted strain at later stages. We show that impaired production of M1 from bird-adapted strains is caused by increased splicing of the M segment RNA to alternative isoforms. Experiments with reporter constructs and recombinant influenza viruses revealed that strain-specific M segment splicing is controlled by the 3’ splice site and functionally important for permissive infection. Independent in silico and biochemical evidence shows that avian-adapted M segments have evolved different conserved RNA structure features than human-adapted sequences. Thus, our data identifies M segment RNA splicing as a viral determinant of host range.
Project description:U3A cells stably expressing wild-type STAT1 or STAT1-CC were treated with interferon beta (10U/ml) or control for 24 hours to assess effects of stat1 modifications, interferon, and the interaction on gene expression. Keywords: interferon, STAT1, STAT1-CC, STAT1CC, STAT-1C, antiviral RNA was isolated from stable U3A-STAT1 lines stably expressing wild-type STAT1 or STAT1CC, after 24 hour treatment with interferon beta (10U/ml) or control.
Project description:Myxomas, the most common primary tumor of the heart, usually develop in the atria and consist of a myxoid matrix composed of an acid-mucopolysaccharide-rich stroma with polygonal stromal cells scattered throughout the matrix. These benign tumors, despite their rarity, are a research focus because of their clinical presentation and uncertain histogenesis. The objective of this study was to assess whether adult cardiac stem/progenitor cells (CSCs) give rise to myxoma stromal cells and secrete the typical myxoid matrix. 23 collected tumors showed the typical histological features of cardiac atrial myxoma with polygonal cells positive for the myxoma tumor-cell marker, calretinin, dispersed in an abundant myxoid matrix. We detected myxoma cells positive for c-kit (c-kitpos) but very rare Isl-1 positive cells. Most of these c-kitpos cells were lineage-committed CD45pos/CD31pos cells. However, c-kitpos /CD45neg/CD31neg cardiac myxoma cells expressed stemness and cardiac progenitor cell transcription factors. Some (<10%) of these c-kitpos/ CD45neg/CD31neg/ myxoma cells expressed also calretinin, representing myxoma stromal precursor cells. c-kitpos/CD45neg/CD31neg cardiac myxoma cells secrete in vitro chondroitin-6-sulfate and hyaluronic acid, composing the gelatinous matrix of cardiac myxoma in vivo. In vitro, c-kitpos/CD45neg/CD31neg myxoma cells have stem cell properties being clonogenic, self-renewing and sphere forming. On the other hand, they exhibited an abortive cardiac differentiation potential with significant changes in their mRNA and microRNA transcriptome compared to normal c-kitpos/CD45neg /CD31neg CSCs. Importantly, myxoma-derived CSCs seed human atrial myxoma in xenograft’s experiments in NOD/SCID mice. Thus, un-committed c-kitpos/CD45neg /CD31neg cells fulfill the criteria of myxoma stem cells in atrial myxoma. Myxomas appear to be the first CSC-related human cardiac disease.
Project description:Myxomas, the most common primary tumor of the heart, usually develop in the atria and consist of a myxoid matrix composed of an acid-mucopolysaccharide-rich stroma with polygonal stromal cells scattered throughout the matrix. These benign tumors, despite their rarity, are a research focus because of their clinical presentation and uncertain histogenesis. The objective of this study was to assess whether adult cardiac stem/progenitor cells (CSCs) give rise to myxoma stromal cells and secrete the typical myxoid matrix. 23 collected tumors showed the typical histological features of cardiac atrial myxoma with polygonal cells positive for the myxoma tumor-cell marker, calretinin, dispersed in an abundant myxoid matrix. We detected myxoma cells positive for c-kit (c-kitpos) but very rare Isl-1 positive cells. Most of these c-kitpos cells were lineage-committed CD45pos/CD31pos cells. However, c-kitpos /CD45neg/CD31neg cardiac myxoma cells expressed stemness and cardiac progenitor cell transcription factors. Some (<10%) of these c-kitpos/ CD45neg/CD31neg/ myxoma cells expressed also calretinin, representing myxoma stromal precursor cells. c-kitpos/CD45neg/CD31neg cardiac myxoma cells secrete in vitro chondroitin-6-sulfate and hyaluronic acid, composing the gelatinous matrix of cardiac myxoma in vivo. In vitro, c-kitpos/CD45neg/CD31neg myxoma cells have stem cell properties being clonogenic, self-renewing and sphere forming. On the other hand, they exhibited an abortive cardiac differentiation potential with significant changes in their mRNA and microRNA transcriptome compared to normal c-kitpos/CD45neg /CD31neg CSCs. Importantly, myxoma-derived CSCs seed human atrial myxoma in xenograft’s experiments in NOD/SCID mice. Thus, un-committed c-kitpos/CD45neg /CD31neg cells fulfill the criteria of myxoma stem cells in atrial myxoma. Myxomas appear to be the first CSC-related human cardiac disease.
Project description:U3A cells stably expressing wild-type STAT1 or STAT1-CC were treated with interferon beta (10U/ml) or control for 24 hours to assess effects of stat1 modifications, interferon, and the interaction on gene expression. Keywords: interferon, STAT1, STAT1-CC, STAT1CC, STAT-1C, antiviral
Project description:Cardiac myxoma is a commonly encountered, potentially life-threatening tumor within the heart. We used single-cell RNA sequencing (scRNA-seq) to analyze the identification and characterization of cellular subtypes, cell trajectory analysis, and intercellular communication of cardiac myxoma tissues.