Project description:In the activated B-cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), the most frequent gain-of-function mutations target MyD88, a signaling adapter for Tolllike receptors (TLRs). The most prevalent oncogenic mutant, MyD88 L265P, occurs in 29% of cases and is the most active in engaging the NF-kappaB pathway. Here we show that MyD88 mutants do not function autonomously, but rather require TLR7, TLR9, and to a lesser extent, TLR4 to promote the survival of ABC DLBCL cells. Unlike wild type MyD88, MyD88 mutants associate constitutively with TLR7 and TLR9 in ABC DLBCL cells. Like ligand-induced TLR7/9 signaling in normal immune cells, the survival of ABC DLBCL cell lines depends upon translocation of TLR7 and TLR9 to acidic endolysosomes, where proteolytic processing of their ligand binding ectodomains is required for their oncogenic signaling. ABC DLBCL viability also depends upon CD14, a co-receptor for TLR7 and TLR9 that promotes engagement of nucleic acid ligands by these receptors. Point mutations in the TLR7 or TLR9 ectodomains that abrogate ligand binding and/or signaling were incapable of sustaining ABC DLBCL survival. An inhibitory oligonucleotide that suppresses TLR9 responses in normal B cells blocked NF-kappaB signaling and survival of ABC DLBCL lines. Together, these data suggest that an endogenous TLR ligand may play a pathogenic role in ABC DLBCL and provide a rationale for targeting TLR signaling to improve therapy of this aggressive lymphoma. Gene expression was analyzed using Agilent human 2-color 4X44K oligo gene expression arrays. Cell line, TMD8 ABC-DLBCL, was infected with control (shControl, Cy3), shLTR7 (Cy5) or shLTR9 (Cy5) and changes in gene expression were monitored on day 1 and day 2 after induction of the shRNA with doxycycline, co-hybridizing control and experimental samples (Cy3+Cy5), for a total of 4 arrays.
Project description:In the activated B-cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), the most frequent gain-of-function mutations target MyD88, a signaling adapter for Tolllike receptors (TLRs). The most prevalent oncogenic mutant, MyD88 L265P, occurs in 29% of cases and is the most active in engaging the NF-kappaB pathway. Here we show that MyD88 mutants do not function autonomously, but rather require TLR7, TLR9, and to a lesser extent, TLR4 to promote the survival of ABC DLBCL cells. Unlike wild type MyD88, MyD88 mutants associate constitutively with TLR7 and TLR9 in ABC DLBCL cells. Like ligand-induced TLR7/9 signaling in normal immune cells, the survival of ABC DLBCL cell lines depends upon translocation of TLR7 and TLR9 to acidic endolysosomes, where proteolytic processing of their ligand binding ectodomains is required for their oncogenic signaling. ABC DLBCL viability also depends upon CD14, a co-receptor for TLR7 and TLR9 that promotes engagement of nucleic acid ligands by these receptors. Point mutations in the TLR7 or TLR9 ectodomains that abrogate ligand binding and/or signaling were incapable of sustaining ABC DLBCL survival. An inhibitory oligonucleotide that suppresses TLR9 responses in normal B cells blocked NF-kappaB signaling and survival of ABC DLBCL lines. Together, these data suggest that an endogenous TLR ligand may play a pathogenic role in ABC DLBCL and provide a rationale for targeting TLR signaling to improve therapy of this aggressive lymphoma.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
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:The ABC subtype of diffuse large B cell lymphoma (DLBCL) remains the least curable form of this lymphoma despite recent advances in therapy. We have combined structural and functional genomics to triangulate on new oncogenic mechanisms and devise new therapeutic strategies. RNA interference screen revealed a dependence of ABC DLBCL cell lines on MYD88 and IRAK1. High throughput resequencing of RNA (RNA-Seq) revealed frequent somatic mutations in MYD88 that preferentially occurred in the ABC DLBCL subtype. Remarkably, one third of ABC DLBCL tumor samples harbored the same amino acid substitution, L265P, in the MYD88 TIR domain at an evolutionarily invariant residue in its hydrophobic core. This mutation was rare or absent in two other DLBCL subtypes, but was observed in 9% of MALT lymphomas. At a lower frequency, multiple other mutations were observed in the MYD88 TIR domain, occurring in both the ABC and GCB subtypes of DLBCL. Survival of ABC DLBCL lines bearing the L265P mutation was sustained by the mutant but not wild type MYD88 isoform, demonstrating that this MYD88 mutant is oncogenic and gain-of-function. The MYD88 L265P mutant assembled a protein complex that spontaneous triggers the phosphorylation of IRAK1, leading to NF-kB signaling, secretion of the cytokines IL-6, IL-10 and interferon-b, and JAK kinase signaling. These findings demonstrate that the MYD88 signaling pathway is integral to the pathogenesis of ABC DLBCL, providing a genetic rationale for therapeutic targeting of the MYD88 signaling pathway in this lymphoma subtype.
Project description:Gene methylation profiling of immortalized human mesenchymal stem cells comparing HPV E6/E7-transfected MSCs cells with human telomerase reverse transcriptase (hTERT)- and HPV E6/E7-transfected MSCs. hTERT may increase gene methylation in MSCs. Goal was to determine the effects of different transfected genes on global gene methylation in MSCs.
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.