Project description:Clinical applications of human interferon (IFN)-alpha have met with varying degrees of success. Nevertheless, key molecules in IFN-alpha-induced cell death have not been clearly identified. Our previous study indicated that IFN (alpha, beta and omega) receptor (IFNAR) 1/2- and IFN regulatory factor (IRF) 9-RNA interference (RNAi) completely inhibited the antiproliferative (AP) activity of IFN-alpha in human ovarian adenocarcinoma OVCAR3 cells sensitive to IFN-alpha., followed by transcription of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, IFNAR1/2- and IRF9-RNAi inhibited the gene expression of TRAIL, but not of Fas ligand (FasL), following IFN-alpha treatment. In fact, TRAIL but not FasL inhibited the proliferation of OVCAR3 cells. IFN-alpha notably up-regulated the levels of TRAIL protein in the supernatant and on the membrane of OVCAR3 cells. Following TRAIL signaling, Caspase 8 inhibitor and BH3 interacting domain death agonist (BID)-RNAi significantly abrogated both AP activities of IFN-alpha and TRAIL. Furthermore, BID-RNAi prevented both IFN-alpha and TRAIL from collapsing the mitochondrial membrane potential (Delta Psi m). Finally, we provide important new evidence that BID overexpression led to a major enhancement of both AP activities of IFN-alpha and TRAIL in human lung carcinoma A549 cells resistant to IFN-alpha. Thus, this study suggests that BID is crucial in IFN-alpha-induced cell death, indicating a notable potential to be a targeted therapy for IFN-alpha resistant tumors. Biological replicate samples were created by treating OVCAR3 cells with IFN-alpha2c (n=8); IFNAR1-RNAi and IFN-alpha2c (n=4); IFNAR2-RNAi and IFN-alpha2c (n=5); ISGF3gamma-RNAi and IFN-alpha2c (n=3); and Negative RNAi and IFN-alpha2c (n=3). For analysis, the eight IFN-alpha2c treated OVCAR3 samples were paired with an untreated OVCAR3 control sample. The 15 RNAi treated OVCAR3 samples were paired with a Negative RNAi control sample.
Project description:Clinical applications of human interferon (IFN)-alpha have met with varying degrees of success. Nevertheless, key molecules in IFN-alpha-induced cell death have not been clearly identified. Our previous study indicated that IFN (alpha, beta and omega) receptor (IFNAR) 1/2- and IFN regulatory factor (IRF) 9-RNA interference (RNAi) completely inhibited the antiproliferative (AP) activity of IFN-alpha in human ovarian adenocarcinoma OVCAR3 cells sensitive to IFN-alpha., followed by transcription of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, IFNAR1/2- and IRF9-RNAi inhibited the gene expression of TRAIL, but not of Fas ligand (FasL), following IFN-alpha treatment. In fact, TRAIL but not FasL inhibited the proliferation of OVCAR3 cells. IFN-alpha notably up-regulated the levels of TRAIL protein in the supernatant and on the membrane of OVCAR3 cells. Following TRAIL signaling, Caspase 8 inhibitor and BH3 interacting domain death agonist (BID)-RNAi significantly abrogated both AP activities of IFN-alpha and TRAIL. Furthermore, BID-RNAi prevented both IFN-alpha and TRAIL from collapsing the mitochondrial membrane potential (Delta Psi m). Finally, we provide important new evidence that BID overexpression led to a major enhancement of both AP activities of IFN-alpha and TRAIL in human lung carcinoma A549 cells resistant to IFN-alpha. Thus, this study suggests that BID is crucial in IFN-alpha-induced cell death, indicating a notable potential to be a targeted therapy for IFN-alpha resistant tumors.
Project description:Dysregulation of professional APC has been postulated as a major mechanism underlying Ag-specific T cell hyporesponsiveness in patients with patent filarial infection. To address the nature of this dysregulation, dendritic cells (DC) and macrophages generated from elutriated monocytes were exposed to live microfilariae (mf), the parasite stage that circulates in blood and is responsible for most immune dysregulation in filarial infections. DC exposed to mf for 24â96 h showed a marked increase in cell death and caspase-positive cells compared with unexposed DC, while mf exposure did not induce apoptosis in macrophages. Interestingly, 48 h exposure of DC to mf induced mRNA expression of the pro-apoptotic gene TRAIL and both mRNA and protein expression of TNF-alpha. mAb to TRAIL-R2, TNF-R1, or TNF-alpha partially reversed mf-induced cell death in DC, as did knocking down the receptor for TRAIL-R2 using small interfering RNA. Mf also induced gene expression of BH3-interacting domain death agonist (Bid) and protein expression of cytochrome c in DC; mf-induced cleavage of Bid could be shown to induce release of cytochrome c, leading to activation of caspase 9. Our data suggest that mf induce DC apoptosis in a TRAIL- and TNF-alpha-dependent fashion. Experiment Overall Design: Microfilariae and human monocyte derived-DCs were cultuted at a multiplicity of infection of 1:1 for 24hrs for four independent donors. Matching samples exposed to media alone were used for controls The four experimental and 4 control samples were then pooled to create one experoimental and one healthy pool used for microarray analysis.
Project description:Dysregulation of professional APC has been postulated as a major mechanism underlying Ag-specific T cell hyporesponsiveness in patients with patent filarial infection. To address the nature of this dysregulation, dendritic cells (DC) and macrophages generated from elutriated monocytes were exposed to live microfilariae (mf), the parasite stage that circulates in blood and is responsible for most immune dysregulation in filarial infections. DC exposed to mf for 24–96 h showed a marked increase in cell death and caspase-positive cells compared with unexposed DC, while mf exposure did not induce apoptosis in macrophages. Interestingly, 48 h exposure of DC to mf induced mRNA expression of the pro-apoptotic gene TRAIL and both mRNA and protein expression of TNF-alpha. mAb to TRAIL-R2, TNF-R1, or TNF-alpha partially reversed mf-induced cell death in DC, as did knocking down the receptor for TRAIL-R2 using small interfering RNA. Mf also induced gene expression of BH3-interacting domain death agonist (Bid) and protein expression of cytochrome c in DC; mf-induced cleavage of Bid could be shown to induce release of cytochrome c, leading to activation of caspase 9. Our data suggest that mf induce DC apoptosis in a TRAIL- and TNF-alpha-dependent fashion. Keywords: Dendritic Cell, Parasite, Human, Microfilariae
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: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.
Project description:PurposeWe investigated the evidence of recent positive selection in the human phototransduction system at single nucleotide polymorphism (SNP) and gene level.MethodsSNP genotyping data from the International HapMap Project for European, Eastern Asian, and African populations was used to discover differences in haplotype length and allele frequency between these populations. Numeric selection metrics were computed for each SNP and aggregated into gene-level metrics to measure evidence of recent positive selection. The level of recent positive selection in phototransduction genes was evaluated and compared to a set of genes shown previously to be under recent selection, and a set of highly conserved genes as positive and negative controls, respectively.ResultsSix of 20 phototransduction genes evaluated had gene-level selection metrics above the 90th percentile: RGS9, GNB1, RHO, PDE6G, GNAT1, and SLC24A1. The selection signal across these genes was found to be of similar magnitude to the positive control genes and much greater than the negative control genes.ConclusionsThere is evidence for selective pressure in the genes involved in retinal phototransduction, and traces of this selective pressure can be demonstrated using SNP-level and gene-level metrics of allelic variation. We hypothesize that the selective pressure on these genes was related to their role in low light vision and retinal adaptation to ambient light changes. Uncovering the underlying genetics of evolutionary adaptations in phototransduction not only allows greater understanding of vision and visual diseases, but also the development of patient-specific diagnostic and intervention strategies.