Project description:Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene segregates with most autoimmune diseases; its risk allele encodes overactive PTPN22 phosphatases that alter B cell receptor (BCR) signaling potentially involved in the regulation of central B cell tolerance. To assess whether PTPN22 risk allele affects the removal of developing autoreactive B cells, we tested by ELISA the reactivity of recombinant antibodies isolated from single B cells from asymptomatic healthy individuals carrying one or two PTPN22 risk allele(s). We found that new emigrant/transitional and mature naive B cells from PTPN22 risk allele carriers contained high frequencies of autoreactive clones compared to non-carrier control donors. Hence, a single PTPN22 risk allele has a dominant effect on altering autoreactive B cell counterselection, suggesting that early B cell tolerance checkpoint defects precede the onset of autoimmunity. In addition, gene array experiments comparing mature naïve B cells from healthy individuals carrying or not PTPN22 risk allele(s) revealed that the strength of association of PTPN22 for autoimmunity, second in importance only to the MHC, may not only be due to BCR signaling alteration but also to the regulation of other genes, which themselves have also been identified as involved in the development of autoimmune diseases. The PTPN22 risk allele is a single nucleotide change (cytidine to thymidine) at residue 1858, which results in a single amino acid substitution from arginine to tryptophan at position 620 of the PTPN22/Lyp protein. Data from mature naïve B cell populations from patients carrying 1 or 2 PTPN22 T alleles and non-carrier patients were compared in order to characterize the impact of PTPN22 polymorphism on B cell physiology. RNA was extracted from batch-sorted CD19+CD10-CD21+CD27- conventional mature naive B cells using the Absolutely RNA microprep kit (Stratagene). 100-200 ng of RNA was obtained per sample, and the quality of the purified RNA was assessed by the Bioanalyzer from Agilent. Using the Ovation biotin system kit from Nugen, 30-50ng of RNA was amplified and labeled to produce cDNA. Labeled cDNA was hybridized on chips containing the whole human genome (Human Genome U133 Plus 2.0 from Affymetrix).
Project description:Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene segregates with most autoimmune diseases; its risk allele encodes overactive PTPN22 phosphatases that alter B cell receptor (BCR) signaling potentially involved in the regulation of central B cell tolerance. To assess whether PTPN22 risk allele affects the removal of developing autoreactive B cells, we tested by ELISA the reactivity of recombinant antibodies isolated from single B cells from asymptomatic healthy individuals carrying one or two PTPN22 risk allele(s). We found that new emigrant/transitional and mature naive B cells from PTPN22 risk allele carriers contained high frequencies of autoreactive clones compared to non-carrier control donors. Hence, a single PTPN22 risk allele has a dominant effect on altering autoreactive B cell counterselection, suggesting that early B cell tolerance checkpoint defects precede the onset of autoimmunity. In addition, gene array experiments comparing mature naïve B cells from healthy individuals carrying or not PTPN22 risk allele(s) revealed that the strength of association of PTPN22 for autoimmunity, second in importance only to the MHC, may not only be due to BCR signaling alteration but also to the regulation of other genes, which themselves have also been identified as involved in the development of autoimmune diseases. The PTPN22 risk allele is a single nucleotide change (cytidine to thymidine) at residue 1858, which results in a single amino acid substitution from arginine to tryptophan at position 620 of the PTPN22/Lyp protein.
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: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:Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IL-1R-associated kinase (IRAK)-4, myeloid differentiation factor 88 (MyD88) and UNC-93B. Indeed, all TLRs except TLR3 require IRAK-4 and MyD88 to signal and UNC-93B-deficient cells are unresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients did not display autoreactive antibodies in their serum nor developed autoimmune diseases, suggesting that IRAK-4, MyD88 and UNC-93B pathway blockade may thwart autoimmunity in humans.
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.