The receptor-interacting protein-associated ICH-1/CED-3 homologous protein with a death domain (Raidd) functions as a dual adaptor protein due to its bipartite nature, and is therefore thought to be a constituent of different multiprotein complexes including the PIDDosome, where it connects the cell death-related protease, Caspase-2, with the p53-induced protein with a death domain 1 (Pidd1). As such, Raidd has been implicated in DNA-damage-induced apoptosis as well as in tumor suppression, the latter based on its role as a direct activator of Caspase-2, known to delay lymphomagenesis caused by overexpression of c-Myc or loss of ATM kinase. As loss of Caspase-2 leads to an acceleration of tumor onset in the E-Myc mouse model we set out to interrogate the role of Raidd in this process in more detail. Our data obtained analyzing E-Myc/Raidd-/- mice indicate that Raidd is unable to protect from c-MYC-driven lymphomagenesis. Similarly, we failed to observe an effect of Raidd-deficiency on thymic lymphomagenesis induced by y-irradiation or fibrosarcoma development driven by 3-methylcholanthrene. The role of Caspase-2 as a tumor suppressor can therefore be uncoupled from its ability to interact and auto-activate upon binding to Raidd. Further, we provide supportive evidence that the tumor suppressive role of Caspase-2 is related to maintaining genomic integrity and allowing efficient p53-mediated signaling. Overall, our findings suggest that Raidd, although described to be the key-adapter allowing activation of the tumor suppressor Caspase-2, fails to suppress tumorigenesis in vivo.
The tumor-modulatory effects of Caspase-2 and Pidd1 do not require the scaffold protein Raidd.
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View SamplesThe subunits of voltage-gated calcium channels regulate surface expression and gating of CaV1 and CaV2 1 subunits, and thus contribute to neuronal excitability, neurotransmitter release and calcium-induced gene regulation. In addition certain subunits are targeted into the nucleus, where they directly interact with the epigenetic machinery. Whereas their involvement in this multitude of functions is reflected by a great molecular heterogeneity of isoforms derived from four genes and abundant alternative splicing, little is known about the roles of individual variants in specific neuronal functions. In the present study, an alternatively spliced 4 subunit lacking the variable N-terminus (4e) is identified. It is highly expressed in mouse cerebellum and cultured cerebellar granule cells (CGC) and modulates P/Q-type calcium currents in tsA cells and CaV2.1 surface expression in neurons. Compared to the other two known full-length 4 variants (4a, 4b) 4e is most abundantly expressed in the distal axon, but lacks nuclear targeting properties. To examine the importance of nuclear targeting of 4 subunits for transcriptional regulation, we performed whole genome expression profiling of CGCs from lethargic mice individually reconstituted with 4a, 4b, and 4e. Notably, the number of genes regulated by each 4 splice variant correlated with the rank order of their nuclear targeting properties (4b> 4a> 4e). Together these findings support isoform-specific functions of 4 splice variant in neurons, with 4b playing a dual role in channel modulation and gene regulation, while the newly detected 4e variant serves exclusively in calcium channel-dependent functions.
Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression.
Specimen part
View SamplesA non-functional myosin Vb motor in duodenal enterocytes results in disruption of epithelial cell polarity characterized by complete loss of microvilli and mislocalization of apical brush border proteins in the cytoplasm which finally cause a devastating disease in neonates with severe malabsorption defects accompanied by protracted diarrhea during infancy, classified as microvillus inclusion disease (MVID). The exact mechanisms how loss-of-function of MYO5B induces polarity loss are not completely understood in MVID pathogenesis. Obtaining better insights in cell polarity defects caused by loss of MYO5B, we performed microarray- in combination with protein expression-analysis in an inducible CaCo2 MYO5B RNAi cell system. Surprisingly, in MYO5B-depleted CaCo2 cells, CDH1 coding for the cell adhesion protein E-Cadherin and important for cell adhesion and therefore maintenance of cell polarity, was significantly downregulated. Interestingly, mesenchymal cell markers, specifically Vimentin and N-Cadherin, physiologically not expressed in differentiated epithelium, were upregulated and accompanied by increased phospho-c-jun levels in the nucleus. Importantly phospho-c-jun was also found in nuclei of duodenal enterocytes in MVID patients, indicating loss of MYO5B induces epithelial cell scattering in enterocytes.
Microvillus inclusion disease: loss of Myosin vb disrupts intracellular traffic and cell polarity.
Specimen part, Cell line
View SamplesThe ESCRT machinery drives the multivesicular body (MVB) pathway in eukaryotic cells and thus is required for the degradation of ubiquitinated membrane proteins in lysosomes. To systematically characterize how cells respond to loss of ESCRT function, we used quantitative proteomics and gene expression profiling in yeast. We find that ESCRT mutants display severe defects in amino acid homeostasis, resulting in lower levels of free intracellular amino acids. This deficit renders the growth of ESCRT mutants highly sensitive to nutrient limitation. Further proteomic analysis revealed that the MVB pathway essentially contributes to proteome remodeling under nutrient limitation. The rapid decline of protein synthesis upon starvation no longer enables ESCRT mutants to complete their cell cycle and properly enter a quiescent state, which strongly affects their long-term survival. Thus, the MVB pathway functions to selectively down-regulate integral membrane proteins and, together with autophagy and proteasomal degradation, considerably contributes to amino acid recycling.
No associated publication
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View SamplesWhy and when the immune system skews to Th2 mediated allergic immune responses is still poorly characterized. With two homologous lipocalins, the major respiratory dog allergen Can f 1 and the human endogenous, non-allergenic Lipocalin-1, we investigated their impact on human monocyte derived dendritic cells (DC). The two lipocalins had differential effects on DC according to their allergenic potential. Compared to Lipocalin-1, Can f 1 persistently induced lower levels of the Th1 skewing maturation marker expression, tryptophan breakdown and IL-12 production in DC. As a consequence, T cells stimulated by DC treated with Can f 1 produced more of the Th2 signature cytokine IL-13 and lower levels of the Th1 signature cytokine IFN- than T cells stimulated by Lipocalin-1 treated DC. These data were partially verified by a second pair of homologous lipocalins, the cat allergen Fel d 4 and its putative human homologue MUP. Our data indicate that the crosstalk of DC with lipocalins alone has the potential to direct the type of immune response to these particular antigens. A global gene expression analysis further supported these results and indicated significant differences in intracellular trafficking, sorting and antigen presentation pathways when comparing Can f 1 and Lipocalin-1 stimulated DC. With this study we contribute to a better understanding of the induction phase of a Th2 immune response.
No associated publication
Treatment
View SamplesThe aim of this study was to analyze the influence of PADMA28 ethanolic extracts on HepG2 gene expression. PADMA28 (Swissmedic Nr. 58436) is an Indo-Tibetan polyherbal preparation used for the treatment of symptoms associated with circulatory disorders.
Pathway-focused bioassays and transcriptome analysis contribute to a better activity monitoring of complex herbal remedies.
Cell line, Treatment
View SamplesIron is an essential component of the erythrocyte protein hemoglobin and is crucial to oxygen transport in vertebrates. In the steady state, erythrocyte production is in equilibrium with erythrocyte removal1. In various pathophysiological conditions, erythrocyte life span is severely compromised, which threatens the organism with anemia and iron toxicity 2,3. Here we identify anon-demand mechanism specific to the liver that clears erythrocytes and recycles iron. We showthat Ly-6Chigh monocytes ingest stressed and senescent erythrocytes, accumulate in the liver, and differentiate to ferroportin 1 (FPN1)-expressing macrophages that can deliver iron to hepatocytes. Monocyte-derived FPN1+ Tim-4neg macrophages are transient, reside alongside embryonically-derived Tim-4high Kuppfer cells, and depend on Csf1 and Nrf2. The spleenlikewise recruits iron-loaded Ly-6Chigh monocytes, but they do not differentiate into ironrecycling macrophages due to the suppressive action of Csf2, and are instead shuttled to the livervia coordinated chemotactic cues. Inhibiting this mechanism by preventing monocyte recruitment to the liver leads to kidney failure and liver damage. These observations identify the liver as the primary organ supporting emergency erythrocyte removal and iron recycling, and uncover a mechanism by which the body adapts to fluctuations in erythrocyte integrity.
On-demand erythrocyte disposal and iron recycling requires transient macrophages in the liver.
Specimen part
View SamplesAdoptive natural regulatory T cell (nTreg) therapy has improved the outcome for patients suffering from graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation (allo-HCT). However, fear of broad immune suppression and subsequent dampening of beneficial graft-versus-leukemic (GVL) responses remains a challenge. To address this concern, we generated alloreactive induced Tregs (iTregs) from resting CD4 or CD8 T cells and tested their ability to suppress GVH and maintain GVL responses. We utilized major mismatched and haploidentical murine models of HCT with host-derived lymphoma or leukemia cell lines to evaluate GVH and GVL responses simultaneously. Alloreactive CD4 iTregs were effective in preventing GVHD, but abrogated the GVL effect against aggressive leukemia. Alloreactive CD8 iTregs moderately attenuated GVHD while sparing the GVL effect. Hence, we reasoned that using a combination of CD4 and CD8 iTregs could achieve the optimal goal of allo-HCT. Indeed, the combinational therapy was superior to CD4 or CD8 iTreg singular therapy in GVHD control; importantly, the combinational therapy maintained GVL responses. Cellular analysis uncovered potent suppression of both CD4 and CD8 effector T cells by the combinational therapy that resulted in effective prevention of GVHD, which could not be achieved by either singular therapy. Gene expression profiles revealed alloreactive CD8 iTregs possess elevated expression of multiple cytolytic molecules compared to CD4 iTregs, which likely contributes to GVL preservation. Our study uncovers unique differences between alloreactive CD4 and CD8 iTregs that can be harnessed to create an optimal iTreg therapy for GVHD prevention with maintained GVL responses.
No associated publication
Specimen part, Treatment
View SamplesBiomarkers that predict disease progression might assist the development of better therapeutic strategies for aggressive cancers, such as ovarian cancer. Here, we investigated the role of collagen type XI alpha 1 (COL11A1) in cell invasiveness and tumor formation and the prognostic impact of COL11A1 expression in ovarian cancer. Microarray analysis suggested that COL11A1 is a disease progression-associated gene that is linked to ovarian cancer recurrence and poor survival.
COL11A1 promotes tumor progression and predicts poor clinical outcome in ovarian cancer.
Specimen part
View SamplesMicroarray analysis of dithranol-treated psoriasis lesions before, during and after therapy
Dithranol targets keratinocytes, their crosstalk with neutrophils and inhibits the IL-36 inflammatory loop in psoriasis.
Time
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