Project description:To investigate the Gene dysregulation caused by loss of RelB and identify candidate genes driving the loss of RelB autoimmune phenotype
Project description:Thymic medullary epithelial cell (mTEC) expression of the autoimmune regulator AIRE, and of tissue-specific antigens, is controlled by members of the non-canonical NF-kB signalling pathway, including RelB and NF-kB2. Of the genes in this pathway, RelB-/- mice develop a particularly severe multi-organ autoimmune syndrome, resembling Foxp3-deficiency. RelB-/- mice have medullary atrophy and few mTECs but the mechanism is unknown. We show that RelB is required for expression of medullary chemokines and mTEC AIRE, selection of a diverse peripheral T cell repertoire, and for peripheral Foxp3+ Treg function. Vβ families of T cells infiltrating diseased peripheral organs and thymic Treg were similarly skewed. Surprisingly, medullary atrophy results from intra-thymic granulocyte infiltration, consequent upon the Th2-mediated autoimmune disease. Dominant tolerance corrects thymic inflammatory disease and loss of thymic function. We demonstrate a reversible RelB-dependent inflammatory mechanism for loss of central tolerance associated with medullary atrophy. Thymi from 4 RelB+/- mice and 3 RelB-/- mice were profiled by microarays
Project description:Thymic medullary epithelial cell (mTEC) expression of the autoimmune regulator AIRE, and of tissue-specific antigens, is controlled by members of the non-canonical NF-kB signalling pathway, including RelB and NF-kB2. Of the genes in this pathway, RelB-/- mice develop a particularly severe multi-organ autoimmune syndrome, resembling Foxp3-deficiency. RelB-/- mice have medullary atrophy and few mTECs but the mechanism is unknown. We show that RelB is required for expression of medullary chemokines and mTEC AIRE, selection of a diverse peripheral T cell repertoire, and for peripheral Foxp3+ Treg function. Vβ families of T cells infiltrating diseased peripheral organs and thymic Treg were similarly skewed. Surprisingly, medullary atrophy results from intra-thymic granulocyte infiltration, consequent upon the Th2-mediated autoimmune disease. Dominant tolerance corrects thymic inflammatory disease and loss of thymic function. We demonstrate a reversible RelB-dependent inflammatory mechanism for loss of central tolerance associated with medullary atrophy.
Project description:The objective of this study was to elucidate the role of Nupr1 in pancreatic tumorigenesis. Using the Pdx-1-cre;LSL-KrasG12D mouse as model we discovered that, in contrast to KrasG12D pancreas that develop multiple foci of pancreatic intraepithelial neoplasia (PanIN), KrasG12D;Nupr1KO pancreas were free from such lesions, indicating that Nupr1 is pivotal for PanIN formation. In vitro, MiaPaCa2 cells activated Nupr1 expression in response to nutrient deprivation and this expression was necessary for cell survival. Mechanistically, Nupr1 protected cells from stress-induced death by inhibiting apoptosis through an alternative RelBàIER3-dependent pathway and independent from activation of the classical RelA-based NF-kB pathway. In agreement with these findings, Nupr1, RelB and IER3 proteins were found co-expressed in PanINs from KrasG12D pancreas. Moreover, pancreas-specific KrasG12D;RelbDpanc mice displayed a delay in PanIN development associated with a lack of IER3 expression, further emphasizing the relevance of this pathway in vivo. Efficient PanIN formation was therefore dependent on the expression of Nupr1 and RelB, with the probable involvement of IER3. Finally, a significant correlation between expression of Nupr1, RelB and IER3 and a poor prognosis of patients with PDAC was found. Altogether, our results reveal a novel stress-related pathway that requires the functional interaction of Nupr1àRelBàIER3 in KrasG12D-dependent transformation of the pancreas and expand our understanding of the molecular machinery that mediates the early steps of pancreatic carcinogenesis. Since Nupr1 belongs to the HMG family of chromatin remodelers with transcriptional co-factor activity, Nupr1 could increase cell survival in a nutrient-deprived microenvironment by activating the expression of pro-survival genes. Moreover, considering that RelB, and not RelA/p65, is essential to the Nupr1-mediated survival mechanism that takes place upon nutrient deprivation-induced stress, we made the hypothesis that the two NF-kB transcription factors should activate different sets of genes among which a pivotal pro-survival gene would be exclusively dependent on RelB. In order to test this two hypothesis, an Affymetrix microarray analysis was performed using pancreatic cancer cells transfected with siCtrl or siNupr1 and cultured for 3, 6 or 9 hrs in EBSS; or transfected with siRelB, siRelA/p65 or siCtrl and cultured for 9 hrs in EBSS or Mock.
Project description:Background: Lymphotoxin signaling via the lymphotoxin-β receptor (LTβR) has been implicated in several biological processes, ranging from development of secondary lymphoid organs, maintenance of splenic tissue, host defense against pathogens, autoimmunity, and lipid homeostasis. The major transcription factor that is activated by LTβR crosslinking is NF-κB. Two signaling pathways have been described that result in the activation of classical p50-RelA and alternative p52-RelB NF-κB heterodimers. Results: Using microarray analysis, we investigated the transcriptional response downstream of the LTβR in mouse embryoni fibroblasts (MEF) and its regulation by the RelA and RelB subunits of NF-κB. We describe novel LTβR-responsive genes that are regulated by RelA and/or RelB. Interestingly, we found that the majority of LTβR-regulated genes require the presence of both RelA and RelB, suggesting significant crosstalk between the two NF-κB activation pathways. Gene Ontology (GO) analysis confirmed that LTβR-NF-κB target genes are predominantly involved in the regulation of immune responses. However, other biological processes, such as apoptosis/cell death, cell cycle, angiogenesis, and taxis were also regulated by LTβR signaling. Moreover, we show that activation of the LTβR inhibits the expression of a key adipogenic transcription factor, peroxisome proliferator activated receptor-γ (pparg), suggesting that LTβR signaling may interfere with adipogenic differentiation. Conclusions: Thus, microarray analysis of LTβR-stimulated fibroblasts revealed further insight into the transcriptional response of LTβR signaling and its regulation by the NF-κB family members RelA and RelB. Keywords: cell type comparison (wt vs relA-/- vs relB-/-) after genetic modification using a time course for each cell type (wt, relA-/-, relB-/-) two time points were analysed (0h as control and 10h) using 3 technical replicates resulting in 18 samples in total
Project description:Background: Lymphotoxin signaling via the lymphotoxin-β receptor (LTβR) has been implicated in several biological processes, ranging from development of secondary lymphoid organs, maintenance of splenic tissue, host defense against pathogens, autoimmunity, and lipid homeostasis. The major transcription factor that is activated by LTβR crosslinking is NF-κB. Two signaling pathways have been described that result in the activation of classical p50-RelA and alternative p52-RelB NF-κB heterodimers. Results: Using microarray analysis, we investigated the transcriptional response downstream of the LTβR in mouse embryoni fibroblasts (MEF) and its regulation by the RelA and RelB subunits of NF-κB. We describe novel LTβR-responsive genes that are regulated by RelA and/or RelB. Interestingly, we found that the majority of LTβR-regulated genes require the presence of both RelA and RelB, suggesting significant crosstalk between the two NF-κB activation pathways. Gene Ontology (GO) analysis confirmed that LTβR-NF-κB target genes are predominantly involved in the regulation of immune responses. However, other biological processes, such as apoptosis/cell death, cell cycle, angiogenesis, and taxis were also regulated by LTβR signaling. Moreover, we show that activation of the LTβR inhibits the expression of a key adipogenic transcription factor, peroxisome proliferator activated receptor-γ (pparg), suggesting that LTβR signaling may interfere with adipogenic differentiation. Conclusions: Thus, microarray analysis of LTβR-stimulated fibroblasts revealed further insight into the transcriptional response of LTβR signaling and its regulation by the NF-κB family members RelA and RelB. Keywords: cell type comparison (wt vs relA-/- vs relB-/-) after genetic modification using a time course
Project description:The objective of this study was to elucidate the role of Nupr1 in pancreatic tumorigenesis. Using the Pdx-1-cre;LSL-KrasG12D mouse as model we discovered that, in contrast to KrasG12D pancreas that develop multiple foci of pancreatic intraepithelial neoplasia (PanIN), KrasG12D;Nupr1KO pancreas were free from such lesions, indicating that Nupr1 is pivotal for PanIN formation. In vitro, MiaPaCa2 cells activated Nupr1 expression in response to nutrient deprivation and this expression was necessary for cell survival. Mechanistically, Nupr1 protected cells from stress-induced death by inhibiting apoptosis through an alternative RelBàIER3-dependent pathway and independent from activation of the classical RelA-based NF-kB pathway. In agreement with these findings, Nupr1, RelB and IER3 proteins were found co-expressed in PanINs from KrasG12D pancreas. Moreover, pancreas-specific KrasG12D;RelbDpanc mice displayed a delay in PanIN development associated with a lack of IER3 expression, further emphasizing the relevance of this pathway in vivo. Efficient PanIN formation was therefore dependent on the expression of Nupr1 and RelB, with the probable involvement of IER3. Finally, a significant correlation between expression of Nupr1, RelB and IER3 and a poor prognosis of patients with PDAC was found. Altogether, our results reveal a novel stress-related pathway that requires the functional interaction of Nupr1àRelBàIER3 in KrasG12D-dependent transformation of the pancreas and expand our understanding of the molecular machinery that mediates the early steps of pancreatic carcinogenesis.
Project description:Recent studies indicated that the NF-kB RelB subunit may play roles beyond immune modulations. The molecular mechanism that may allow RelB to engage in such diverse physiological activities remains unclear. To better understand the RelB-driven transcriptome, therefore, we subjected wild type and Relb-/- mouse embryonic fibroblast (MEF) to microarray analyses using Illumina MouseRef-8 v2.0 Expression BeadChip. We propose that our transcroptomic analyses will help linking RelB to other important cellular pathways.