Project description:Abnormal mitochondria metabolism and innate immune responses participate in the pathogenesis of many inflammatory disorders. The molecular events regulating mitochondrial activity to control survival and cell death in monocytes/macrophages are poorly understood. Here we show that miR-125b attenuates the activity of the mitochondrial respiratory chain through BIK silencing, and promotes the elongation of mitochondrial network through MTP18 targeting, without impacting autophagy, in the human monocytes. Proinflammatory activation is associated with a concomitant increase in miR-125b expression, decrease in BIK and MTP-18 expression, reduced oxidative phosphorylation, and enhanced mitochondrial fusion. Furthermore, expression of M1-associated transcripts as well as mitochondrial dynamics and energy metabolism are induced upon ectopic expression of miR-125b. In turn, by repressing miR-125b, mitochondrial dynamics was preserved, LPS-induced repression of BIK expression and of mitochondrial respiration were prevented, and M1 polarization of macrophages was inhibited. Altogether, our data reveal a novel role for miR-125b in controlling mitochondrial metabolism and dynamics by targeting BIK and MTP18, respectively, two novel cellular target proteins involved in maintaining the mitochondrial integrity in human monocytes. These findings not only suggest a novel function for miR-125b in regulating metabolic adaptation of monocytes to inflammation but also unravel new molecular mechanisms for its pro-apoptotic role and identify potential targets for interfering with inflammatory activation of monocytes.
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: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:B-cell acute lymphoblastic leukemia (B-ALL) is often associated with chromosomal translocations leading to the deregulation of proto-oncogenes. MicroRNAs can also be affected by chromosomal alterations and thus contribute to carcinogenesis. The microRNA miR-125b-1 is over-expressed in B-ALL cases with the t(11;14)(q24;q34) translocation, therefore we sought to determine the role of this microRNA in B-cell fate. We used murine pre-BI cells alongside murine and human leukemic B-cell lines to show that miR-125b expression enhances proliferation by targeting Bright/ARID3a, an activator of immunoglobulin heavy-chain transcription. Accordingly, this target gene was down-regulated in B-ALL patients with the t(11;14)(q24;q34) translocation. Repression of Bright/ARID3A blocked differentiation and conferred a survival advantage to Ba/F3 cells under IL3 starvation. In addition, over-expression of miR-125b protected pre-BI and leukemic B-cell lines from apoptosis through blockade of caspase activation via a mechanism that was independent of p53 and BAK1. In summary, miR-125b can act as an oncogene in B-ALL by targeting ARID3a and mediating its repression, thus leading to a blockage in differentiation, increased proliferation and inhibition of apoptosis. To identify specific targets of mir-125b, we overexpressed miR-125b as well as a control miRNA in 70Z/3 and 18-81 pre-B leukaemia cells. Chemically synthesized miRNA duplexes, called pre-miR-125b and miR-Neg, were purchased from Ambion. The cells were transfected with pre-miRNA at a final concentration of 10 nM using Lipofectamin RNAi MAX (Invitrogen) according to the manufacturer’s instructions. The medium was replaced 8 hours after transfection. RNA samples were harvested at 48 hours post-transfection. 2 independent experiments were carried out for a total of 8 samples labeled with Cy3 dye (one color design).
Project description:In this study, we characterize the fusion protein produced by the EPC1-PHF1 translocation in Low Grade Endometrial Stromal Sarcoma (LG-ESS) and Ossifying FibroMyxoid Tumors (OFMT). We express the fusion protein and necessary controls in K562 Cells. The fusion protein assembles a mega-complex harboring both NuA4/TIP60 and PRC2 subunits and enzymatic activities and leads to mislocalization of chromatin marks in the genome, linked to aberrant gene expression.
Project description:To assess RNA regulation in the MN possessing mutated FUS-H517D gene. Fused in sarcoma/translated in liposarcoma (FUS) is a causative gene of familial amyotrophic lateral sclerosis (fALS). Mutated FUS causes accumulation of DNA damage stress and stress granule (SG) formation, etc., thereby motor neuron (MN) death. However, key molecular etiology of mutated FUS-dependent fALS (fALS-FUS) remains unclear. Here, Bayesian gene regulatory networks (GRN) calculated by Super-Computer with transcriptome data sets of induced pluripotent stem cell (iPSC)-derived MNs possessing mutated FUSH517D (FUSH517D MNs) and FUSWT identified TIMELESS, PRKDC and miR-125b-5p as "hub genes" which influence fALS-FUS GRNs. miR-125b-5p expression up-regulated in FUSH517D MNs, showed opposite correlations against FUS and TIMELESS mRNA levels as well as reported targets of miR-125b-5p. In addition, ectopic introduction of miR-125b-5p could suppress mRNA expression levels of FUS and TIMELESS in the cells. Furthermore, we found TIMELESS and PRKDC among key players of DNA damage stress response (DDR) were down-regulated in FUSH517D MNs and cellular model analysis validated DDR under impaired DNA-PK activity promoted cytosolic FUS mis-localization to SGs. Our GRNs based on iPSC models would reflect fALS-FUS molecular etiology.
Project description:To investigate the gene expresiion regulated by miR-125b and its isomiRs. We transfected H9C2 cells with respective mimics and performed gene expression profiling anlaysis using data from RNA-seq of mimic controls, miR-125b and its isomiRs mimics subjected to normoxia and hypoxia treatment.
Project description:As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain.A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development.Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines.