Project description:Expression profiling of rat major histocompatibility complex and natural killer complex genes in skin explant assays reveals genes that are regulated in graft versus host disease. The major histocompatibility complex (MHC) is the most important genomic region that contributes to the genetic risk of graft rejection and graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Therefore, MHC matching is most essential for the success of clinical transplantations. However, the MHC contains in addition to MHC class I and class II genes that are genotyped for selection of donors further so far unidentified genes that also contribute significantly to the risk to develop acute GVHD. It is difficult to identify these MHC genes by genetic association studies alone due to linkage disequilibrium in this region. Therefore, we aimed to identify MHC genes that might be involved in the pathohysiology of GVHD by expression profiling. To reduce the complexity of our model, we used genetically well-defined inbred rat strains (PVG and BN) and skin explant assays, an in-vitro-model of graft versus host reaction (GVHR), to analyse the expression of MHC and natural killer complex (NKC) genes in a cutaneous GVHR by a custom microarray. A higher percentage of genes in these immunologically highly important genomic regions were regulated than in the rest of the genome. We observed a statistically significant regulation of 25 MHC and 6 NKC genes and 168 other genes (i.e., 4.9%, 14.0%, and 6.6%, respectively) in rat skin explants cultured in the presence of pre-stimulated allogeneic lymphocytes compared to control samples cultured in the presence of syngeneic lymphocytes. Seven MHC and 3 NKC genes were selected for analysis by quantitative real-time polymerase chain reaction PCR. Most of the results of the microarray were confirmed in the same experimental set that was used for the microarray analysis and in a second independent experimental set of skin explant samples. In addition, GVHD-affected skin lesions of transplanted rats were analysed and similar regulations of most of the selected MHC and NKC genes were observed. Thus, our skin explant model of GVHR is informative for the gene regulation during GVHD. Interestingly, the human homologues of several of the regulated genes are polymorphic and could therefore contribute to the genetic risk of GVHD. These genes include RT1-Dmb, C2, Aif1, Spr1, Ubd, and Olr1. The human homologues of these genes might be useful for risk assessment and diagnosis of GVHD in patients. Two-condition experiment, Stimulated vs. NonSimulated cells. 12 Biological replicates, 2 Technical Replicates (Dye Swap) per Biological Replicate.

Project description:Expression profiling of rat major histocompatibility complex and natural killer complex genes in skin explant assays reveals genes that are regulated in graft versus host disease. The major histocompatibility complex (MHC) is the most important genomic region that contributes to the genetic risk of graft rejection and graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Therefore, MHC matching is most essential for the success of clinical transplantations. However, the MHC contains in addition to MHC class I and class II genes that are genotyped for selection of donors further so far unidentified genes that also contribute significantly to the risk to develop acute GVHD. It is difficult to identify these MHC genes by genetic association studies alone due to linkage disequilibrium in this region. Therefore, we aimed to identify MHC genes that might be involved in the pathohysiology of GVHD by expression profiling. To reduce the complexity of our model, we used genetically well-defined inbred rat strains (PVG and BN) and skin explant assays, an in-vitro-model of graft versus host reaction (GVHR), to analyse the expression of MHC and natural killer complex (NKC) genes in a cutaneous GVHR by a custom microarray. A higher percentage of genes in these immunologically highly important genomic regions were regulated than in the rest of the genome. We observed a statistically significant regulation of 25 MHC and 6 NKC genes and 168 other genes (i.e., 4.9%, 14.0%, and 6.6%, respectively) in rat skin explants cultured in the presence of pre-stimulated allogeneic lymphocytes compared to control samples cultured in the presence of syngeneic lymphocytes. Seven MHC and 3 NKC genes were selected for analysis by quantitative real-time polymerase chain reaction PCR. Most of the results of the microarray were confirmed in the same experimental set that was used for the microarray analysis and in a second independent experimental set of skin explant samples. In addition, GVHD-affected skin lesions of transplanted rats were analysed and similar regulations of most of the selected MHC and NKC genes were observed. Thus, our skin explant model of GVHR is informative for the gene regulation during GVHD. Interestingly, the human homologues of several of the regulated genes are polymorphic and could therefore contribute to the genetic risk of GVHD. These genes include RT1-Dmb, C2, Aif1, Spr1, Ubd, and Olr1. The human homologues of these genes might be useful for risk assessment and diagnosis of GVHD in patients.

Project description:A series of two color gene expression profiles obtained using Agilent 44K expression microarrays was used to examine sex-dependent and growth hormone-dependent differences in gene expression in rat liver. This series is comprised of pools of RNA prepared from untreated male and female rat liver, hypophysectomized (‘Hypox’) male and female rat liver, and from livers of Hypox male rats treated with either a single injection of growth hormone and then killed 30, 60, or 90 min later, or from livers of Hypox male rats treated with two growth hormone injections spaced 3 or 4 hr apart and killed 30 min after the second injection. The pools were paired to generate the following 6 direct microarray comparisons: 1) untreated male liver vs. untreated female liver; 2) Hypox male liver vs. untreated male liver; 3) Hypox female liver vs. untreated female liver; 4) Hypox male liver vs. Hypox female liver; 5) Hypox male liver + 1 growth hormone injection vs. Hypox male liver; and 6) Hypox male liver + 2 growth hormone injections vs. Hypox male liver. A comparison of untreated male liver and untreated female liver liver gene expression profiles showed that of the genes that showed significant expression differences in at least one of the 6 data sets, 25% were sex-specific. Moreover, sex specificity was lost for 88% of the male-specific genes and 94% of the female-specific genes following hypophysectomy. 25-31% of the sex-specific genes whose expression is altered by hypophysectomy responded to short-term growth hormone treatment in hypox male liver. 18-19% of the sex-specific genes whose expression decreased following hypophysectomy were up-regulated after either one or two growth hormone injections. Finally, growth hormone suppressed 24-36% of the sex-specific genes whose expression was up-regulated following hypophysectomy, indicating that growth hormone acts via both positive and negative regulatory mechanisms to establish and maintain the sex specificity of liver gene expression. For full details, see V. Wauthier and D.J. Waxman, Molecular Endocrinology (2008)

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Rattus norvegicus

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