Project description:Macrophages play a crucial role in HIV-1 pathogenesis. Toll-like receptors (TLRs) are fundamental for innate and adaptive immune responses, but their role in HIV-1 infection is still incompletely understood. The TLR3 and TLR4 ligands poly(I:C) and LPS are known to modulate HIV-1 infection of and replication in monocyte-derived macrophages (MDMs), but the mechanism is incompletely understood. We found that MDMs stimulation with poly(I:C) or LPS abrogated infection by CCR5-using, macrophage-tropic HIV-1, or by VSV-G-pseudotyped HIV-1 virions, while TLR7 and TLR9 agonists Imiquimod and CpG only reduced infection to varying extent. Suppression of infection, or lack thereof, did not correlate with differential effects on CD4 or CCR5 expression, type I interferon induction, or production of pro-inflammatory cytokines. Furthermore, integrated pro-viruses were readily detected in unstimulated, TLR7- and TLR9-stimulated cells, but not in TLR3- or TLR4-stimulated MDMs, suggesting the alteration of post-entry, pre-integration event(s). MicroRNA (miRNA) microarray and real time PCR demonstrated increased miR-155 levels in MDMs upon TLR3/4, but not TLR7, stimulation, and a miR-155 inhibitor partially restored infectivity in poly(I:C)-stimulated MDMs. Finally, miR-155 over-expression in MDMs and cell lines remarkably diminished HIV-1 infection, inducing an accumulation of late reverse transcription products, concurrently with a decrease in mRNA levels of several HIV-1 dependency factors involved in nuclear import of pre-integration complexes. Our results suggest that miR-155 may target mRNA(s) for host cell protein(s) that either participate in or facilitate post-entry, pre-integration events, resulting in severely diminished HIV-1 infection. miRNA profiles were investigated in total RNA isolated from unstimulated and TLR3-, TLR4- and TLR7-stimulated human MDMs from a single normal donor
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Macrophages play a crucial role in HIV-1 pathogenesis. Toll-like receptors (TLRs) are fundamental for innate and adaptive immune responses, but their role in HIV-1 infection is still incompletely understood. The TLR3 and TLR4 ligands poly(I:C) and LPS are known to modulate HIV-1 infection of and replication in monocyte-derived macrophages (MDMs), but the mechanism is incompletely understood. We found that MDMs stimulation with poly(I:C) or LPS abrogated infection by CCR5-using, macrophage-tropic HIV-1, or by VSV-G-pseudotyped HIV-1 virions, while TLR7 and TLR9 agonists Imiquimod and CpG only reduced infection to varying extent. Suppression of infection, or lack thereof, did not correlate with differential effects on CD4 or CCR5 expression, type I interferon induction, or production of pro-inflammatory cytokines. Furthermore, integrated pro-viruses were readily detected in unstimulated, TLR7- and TLR9-stimulated cells, but not in TLR3- or TLR4-stimulated MDMs, suggesting the alteration of post-entry, pre-integration event(s). MicroRNA (miRNA) microarray and real time PCR demonstrated increased miR-155 levels in MDMs upon TLR3/4, but not TLR7, stimulation, and a miR-155 inhibitor partially restored infectivity in poly(I:C)-stimulated MDMs. Finally, miR-155 over-expression in MDMs and cell lines remarkably diminished HIV-1 infection, inducing an accumulation of late reverse transcription products, concurrently with a decrease in mRNA levels of several HIV-1 dependency factors involved in nuclear import of pre-integration complexes. Our results suggest that miR-155 may target mRNA(s) for host cell protein(s) that either participate in or facilitate post-entry, pre-integration events, resulting in severely diminished HIV-1 infection.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes Sequence library of miRNAs from a single sample of human foetal mesenchymal stem cells. Results tested and confirmed by northern blotting. Please note that only raw data files are available for the embryonic and neual samples and thus, directly submitted to SRA (SRX547311, SRX548700, respectively under SRP042115/PRJNA247767)
Project description:The innate immune system is vital to rapidly responding to pathogens and Toll-like receptors (TLRs) are a critical component of this response. Nanovesicular exosomes play a role in immunity, but to date their exact contribution to the dissemination of the TLR response is unknown. To understand the effect of exosomal cargo released from locally stimulated cells on distal cell expression, we collected exosomes from local ovarian adenocarcinoma (HEY) cells that were either unstimulated (control-exosomes), stimulated with pIC (pIC-exosomes), or lipopolysaccharide (LPS-exosomes) for 48 hours. The three groups of exosomes were added to naïve (distal) cells and the gene expression profiles were compared between local TLR stimulation (for 6 hours) and distal stimulation mediated by exosomes at the 48-hour time point The goal of the study was to delineate the differential effector function of TLR-exosomes based on the innate immune activation state (control-, LPS-, pIC-stimulation) of the cell of origin in vitro. We used microarrays to understand the changes in gene expression in 2 samples of local hey cells either unstimulated(control) or stimulated with poly(I:C) or LPS each. We also profiled 2 samples of distal naïve cells that were exposed to either control, LPS or poly(I:C) exosomes from local cells. Here we show that exosomes from TLR stimulated cells (TLR-exosomes) can largely recapitulate TLR activation in distal cells in vitro. We can abrogate the action-at-a-distance signaling of exosomes by UV irradiation, demonstrating that RNA is crucial for their effector function. This work definitively establishes the differential effector function for TLR-exosomes in communicating the activation state of the cell of origin.