Expression Profiling of Major Histocompatibility and Natural Killer Complex Genes Reveals Candidates for Controlling Risk of Graft versus Host Disease

Background: The major histocompatibility complex (MHC) is the most important genomic region that contributes to the risk of graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Matching of MHC class I and II genes is essential for the success of transplantation. However, the MHC contains additional genes that also contribute to the risk of developing acute GVHD. It is difficult to identify these genes by genetic association studies alone due to linkage disequilibrium in this region. Therefore, we aimed to identify MHC genes and other genes involved in the pathophysiology of GVHD by mRNA expression profiling. Methodology/Principal Findings: To reduce the complexity of the task, we used genetically well-defined rat inbred strains and a rat skin explant assay, an in-vitro-model of the graft versus host reaction (GVHR), to analyze the expression of MHC, natural killer complex (NKC), and other genes in cutaneous GVHR. We observed a statistically significant and strong up or down regulation of 11 MHC, 6 NKC, and 168 genes encoded in other genomic regions, i.e. 4.9%, 14.0%, and 2.6% of the tested genes respectively. The regulation of 7 selected MHC and 3 NKC genes was confirmed by quantitative real-time PCR and in independent skin explant assays. In addition, similar regulations of most of the selected genes were observed in GVHD-affected skin lesions of transplanted rats and in human skin explant assays. Conclusions/Significance: We identified rat and human MHC and NKC genes that are regulated during GVHR in skin explant assays and could therefore serve as biomarkers for GVHD. Several of the respective human genes, including HLA-DMB, C2, AIF1, SPR1, UBD, and OLR1, are polymorphic. These candidates may therefore contribute to the genetic risk of GVHD in patients

Thymic alterations in mice deficient for the SNARE protein VAMP8/endobrevin

Kanwar N, Fayyazi A, Backofen B, Nitsche M, Dressel R, Fischer von Mollard G. Thymic alterations in mice deficient for the SNARE protein VAMP8/endobrevin. CELL AND TISSUE RESEARCH. 2008;334(2):227-242

Histone Deacetylase 9 couples neuronal activity to muscle chromatin acetylation and gene expression

International audienceElectrical activity arising from motor innervation influences skeletal muscle physiology by controlling the expression of many muscle genes, including acetylcholine receptor (AChR) subunits genes. How electrical activity is converted into a transcriptional response remains largely unknown. We show that motor innervation controls chromatin acetylation in skeletal muscle and that histone deacetylase 9 (HDAC9) is a signal-responsive transcriptional repressor, which is down-regulated upon denervation, with consequent up-regulation of chromatin acetylation and AChR expression. Forced expression of HDAC9 in denervated muscle prevents up-regulation of activity-dependent genes and chromatin acetylation by linking MEF2 and class I HDACs. Conversely, HDAC9 null mice are supersensitive to denervation-induced changes in gene expression and display chromatin hyperacetylation, and delayed perinatal downregulation of myogenin, an activator of AChR genes. These findings reveal a molecular mechanism to account for the control of chromatin acetylation by presynaptic neurons and activity-dependent regulation of skeletal muscle genes by motor innervation