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The expression of Ig-like transcript (ILT) inhibitory receptors is a characteristic of tolerogenic dendritic cells (DCs). However, the mechanisms of modulation of DCs via ILT receptors remain poorly defined. HLA-G is a preferential ligand for several ILTs. Recently, we demonstrated that triggering of ILT4 by HLA-G1 inhibits maturation of human monocyte-derived conventional DCs and murine DCs from ILT4 transgenic mice, resulting in diminished expression of MHC class II molecules, CD8O and CD86 costimulatory molecules, and prolongation of skin allograft survival. Different isoforms of HLA-G have diverse effects on the efficiency to induce ILT-mediated signaling. In this work, we show that HLA-G1 tetrameric complex and HLA-G5 dimer, but not HLA-G5 monomer, induce strong ILT-mediated signaling. We determined that the arrest of maturation of ILT4-positive DCs by HLA-G Iigands involves the IL-6 signaling pathway and STAT3 activation. Ligation of ILT4 with HLA-G on DCs results in recruitment of SHP-1 and SHP-2 protein tyrosine phosphatases. We propose a model where SHP-2 and the IL-6-STAT3 signaling pathway play critical roles in the modulation of DC differentiation by ILT4 and HLA-G. [ABSTRACT FROM AUTHOR]

The tyrosine phosphatase PTPN22 allele 1858T has been associated with rheumatoid arthritis (RA) and other autoimmune diseases. RA is the most frequent of those multifactorial diseases. The RA association was usually restricted to serum rheumatoid factor positive disease (RF+). No interaction was shown with HLA-DRB1, the first RA gene. Many case-control studies replicated the RA association, showing an allele frequency increase of +5% on average and large variations of population allele frequencies (2.1-15.5%). In multifactorial diseases, the final proof for a new susceptibility allele is provided by departure from Mendel's law (50% transmission from heterozygous parents). For PTPN22-1858T allele, convincing linkage proof was available only for type 1 diabetes. We aimed at providing this proof for RA. We analyzed 1,395 West European Caucasian individuals from 465 "trio" families. We replicated evidence for linkage, demonstrating departure from Mendel's law in this subset of early RA onset patients. We estimated the overtransmission of the 1858T allele in RF+ families: T = 63%, P < 0.0007. The 1858T allele frequency increased from 11.0% in controls to 17.4% in RF+ RA for the French Caucasian population and the susceptibility genotype (1858T/Tor TIC) from 20.2% to 31.6% [odds ratio (OR) = 1.8 (1.2-2.8)]. In conclusion, we provided the linkage proof for the PTPN22-1858T allele and RF+ RA. With diabetes and RA, PTPN22 is therefore a "linkage-proven" autoimmunity gene. PTPN22 accounting for ≈1% of the RA familial aggregation, many new genes could be expected that are as many leads to definitive therapy for autoimmune diseases. [ABSTRACT FROM AUTHOR]

Fanconi anemia (FA) is a rare inherited genomic instability syndrome representing one of the best examples of hematopoietic stem cell deficiency. Although FA might be an excellent candidate for bone marrow (BM) genetic correction ex vivo, knockout animal models are not sufficient to guide preclinical steps, and gene therapy attempts have proven disappointing so far. Contributing to these poor results is a characteristic and dramatic early BM-cells die-off when placed in culture. We show here that human primary FA BM cell survival can be ameliorated by using specific culture conditions that limit oxidative stress. When coupled with retrovirus-mediated transfer of the main complementation group FANCA- cDNA, we could achieve long-term reconstitution of the stem cell compartment both in vitro and in vivo. Gene-corrected BM cultures grew for >120 days, and after cultured cell transplantation into NOD/SCID mice, clonogenic human cells carrying the FANCA transgene could be detected 6 months after transduction. By comparison, untransduced cells died in culture by 15 days. Of necessity for ethical reasons, experiments were conducted on a very limited number of primary BM cells. By using low cytokine regimen and conditions matching regulatory requirements, a contingent of gene-corrected cells slowly emerges with an unmet potential for in vivo engraftment. Future therapeutic applications of stem cells might be expanding from these data. In addition, we provide a model of gene-corrected human primary cell growth that carries the potential to better delineate the combined role of both DNA damage and oxidative stress in the pathogenesis of FA. [ABSTRACT FROM AUTHOR]

To investigate tumor resistance to T cell lysis, a resistant variant was selected after specific cytolytic T lymphocytes (CTL) selection pressure. Although the resistant variant triggered perform and granzyme B transcription in specific CTLs, as well as their degranulation, it exhibited a dramatic resistance to cytotoxic T cell killing. It also displayed strong morphological changes with alterations of the actin cytoskeleton. Electron microscopy analysis revealed a loosen interaction between CTL5 and the resistant variant despite the formation of apparently normal conjugates. Transcriptional profiling identified a gene expression signature that distinguished sensitive from resistant tumor targets. More notably, we found that actin-related genes ephrin-A1 and scinderin were overexpressed in resistant target. Silencing of these genes using RNA interference resulted in a restoration of normal cell morphology and a significant attenuation of variant resistance to CTL killing. Our present study shows that a shift in cytoskeletal organization can be used, by tumor cells, as a strategy to promote their resistance after CTL selection pressure. [ABSTRACT FROM AUTHOR]

The 8.1 haplotype of the HLA complex has been reproducibly associated with several autoimmune diseases and traits, notably with thymus hyperplasia in patients with acquired generalized myasthenia gravis, an autoantibody-mediated disease directed at the muscle acetylcholine receptor. However, the strong linkage disequilibrium across this haplotype has prevented the identification of the causative locus, termed MYAS1. Here, we localized MYAS1 to a 1.2-Mb genome segment by reconstructing haplotypes and assessing their transmission in 73 simplex families. This segment encompasses the class Ill and proximal class I regions, between the BAT3 and C3-2-1 I markers, therefore unambiguously excluding the class II loci. ln addition, a case-control study revealed a very strong association with a core haplotype in this same region following an additive model (P = 7 × 10-11, odds ratio 6.5 for one copy and 42 for two copies of the core haplotype). Finally, we showed that this region is associated with a marked increase in serum titers of anti-acetylcholine receptor autoantibodies (P = 8 × 10-6). Remarkably, this effect was suppressed by a second locus in cis on the 8.1 haplotype and located toward the class II region. Altogether, these data demonstrate the highly significant but complex effects of the 8.1 haplotype on the phenotype of myasthenia gravis patients and might shed light on its role in other autoimmune diseases. [ABSTRACT FROM AUTHOR]

We analysed the regulation of human leucocyte antigen (HLA)-E, -F and -G genes, focusing on the SXY module, a promoter region that controls major histocompatibility complex (MHC) class II expression and participates in the expression of classical HLA class I molecules. It comprises the X1, X2 and Y boxes, bound by RFX, X2-BP/ATF/CREB and NFY factors, respectively. The complex recruits the master control factor CIITA. The SXY module is conserved in HLA-E and HLA-F gene promoters, whereas in the HLA-G promoter, the only conserved boxes are S and X1. Chromatin immunoprecipitation assays, performed on HLA-G positive and negative cell lines, demonstrated the in situ binding of RFX5 and CIITA to HLA-E and HLA-F, but not to HLA-G, promoters. In B cells from bare lymphocyte syndrome patients lacking RFX5 or CIITA, we observed lower steady-state levels of HLA-E and HLA-F transcripts but did not find any significant decrease in the cell-surface expression of HLA-E/classical HLA class I. In RFX5-deficient fibroblasts, the cell-surface expression of HLA molecules was decreased. RFX5 and CIITA are thus not involved in HLA-G expression and their importance for the surface expression of HLA-E/classical HLA class I molecules may vary depending on the cell type. [ABSTRACT FROM AUTHOR]

Background/Aims: Liver allograft is known to protect simultaneously transplanted organs from acute rejection. We have reported that only 6% of combined liver-kidney recipients, versus 32.5% of kidney recipients, develop kidney graft acute rejection. Release of soluble human leukocyte antigen (HLA) molecules by the liver has been proposed as a possible tolerogenic mechanism involved in the better acceptance of double transplants. The HLA-G molecule is acknowledged to possess tolerogenic properties.Methods: We investigated the involvement of HLA-G in allogeneic transplant acceptance by analyzing its expression in kidney and liver biopsies of 40 combined transplanted patients.Results: We demonstrate the presence of HLA-G in 14 out of 40 liver and five out of nine kidney transplants biopsies. HLA-G is expressed de novo by cells that are otherwise frequently susceptible target cells of acute rejection, i.e. liver biliary and renal tubular epithelial cells. We show a significant association between HLA-G expression in liver biliary epithelial cells and the absence of liver graft rejection. No acute or chronic rejection of the kidney graft was observed in patients in whom HLA-G was expressed in the liver graft.Conclusions: HLA-G expression in the liver allograft is associated with a lower frequency of hepatic and renal acute rejection and may be involved in the acceptance of simultaneously transplanted organs. [Copyright &y& Elsevier]

The p53 tumor suppressor protein plays a crucial role in tumorigenesis by controlling cell-cycle progression and apoptosis. We have previously described a transcript designated tumor suppressor activated pathway-6 (TSAP6) that is up-regulated in the p53inducible cell line, LTR6. Cloning of the murine and human fulllength TSAP6 cDNA revealed that it encodes a 488-aa protein with five to six transmembrane domains. This gene is the murine and human homologue of the recently published rat pHyde. Antibodies raised against murine and human TSAP6 recognize a 50- to 55-kDa band induced by p53. Analysis of the TSAP6 promoter identified a functional p53-responsive element. Functional studies demonstrated that TSAP6 antisense cDNA diminished levels of the 50- to 55-kDa protein and decreased significantly the levels of p53induced apoptosis. Furthermore, TSAP6 small interfering RNA inhibited apoptosis in TSAP6-overexpressing cells. Yeast two-hybrid analysis followed by GST/in vitro-transcribed/translated pulldown assays and in vivo coimmunoprecipitations revealed that TSAP6 associated with Nix, a proapoptotic Bcl-2-related protein and the Myt1 kinase, a negative regulator of the G[sub 2]/M transition. Moreover, TSAP6 enhanced the susceptibility of cells to apoptosis and cooperated with Nix to exacerbate this effect. Cell-cycle studies indicated that TSAP6 could augment Myt1 activity. Overall, these data suggest that TSAP6 may act downstream to p53 to interface apoptosis and cell-cycle progression. [ABSTRACT FROM AUTHOR]

The HLA-G molecule plays an important role in immune tolerance, protecting the fetus from maternal immune attack, and probably contributes to graft tolerance and tumor escape from the host immune system. HLA-G expression is tightly regulated and involves mechanisms acting in part at the transcriptional level. Nevertheless, almost all regulatory sequences that govern constitutive and inducible HLA class I gene transcription are disrupted in the HLA-G gene promoter, suggesting an unusual regulatory process, in further investigating the molecular mechanisms of HLA-G gene activation, we evaluated the influence of epigenetic mechanisms on seven HLA-G-negative cell lines that exhibit various phenotypes. Exposure of cells to histone deacetylase inhibitors, or to the demethylating agent 5-aza-2'-deoxycytidine, revealed that HLA-G gene transcription is inhibited by DNA methylation. Reversal of methylation-mediated repression may directly induce HLA-G cellsurface expression, supporting the idea that HLA-G might be activated by such a mechanism during malignancy, inflammation, and allogenic reactions. [ABSTRACT FROM AUTHOR]

Examines the impact of expanded polyglutamines in Caenorhabditis elegans on axonal abnormalities and neuronal dysfunction. Role of amino acid in protein huntington; Effect of nematode on Caenorhabditis elegans; Components of Huntington's disease pathogenesis.

Presents the biochemical, neuropathologic and genetic evidence for a role of the Gln-Ala repeat transcriptional activator CA150 in Huntington's disease pathogenesis. Interaction of Caenorhabditis elegans ZK1127.9 with htt in two-hybrid tests; In vitro interaction of CA150 with full-length htt from lymphoblastoid cells.

Investigates the effects of presenilin 1 (PS1) on apoptosis in both p53-dependent and p53-independent systems as well as the consequences of p53 deficiency on PS1 regulation, apoptosis in the brains and neurobehavioral functions in p53 knockout mice. Antiapoptotic function of PS1; Common downstream effector genes between p53-p21[sup waf1] and PS1.

Examines the expression of the histocompatibility antigens-G (HLA-G) and the natural killer sensitivity in the human malignant melanoma cells. What the analysis of the three melanoma cell lines and ex vivo biopsy demonstrated; Implication of the concept of immunosurveillance; Information on the indications of the results.