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Norrin/Frizzled4 signalling in the preneoplastic niche blocks medulloblastoma initiation.
Specimen part
View SamplesMedulloblastoma (MB), a tumor of the cerebellum, is the most common malignant brain tumor in children. One third of all human MB exhibits a gene expression signature of Sonic hedgehog (Shh) signaling. Hedgehog (Hh) pathway inhibitors have shown efficacy in clinical trials for MB, however, tumors develop resistance to these compounds, highlighting the need to identify additional therapeutic targets for treatment. We have identified a role for Norrin signaling in tumor initiation in the Patched (Ptch) mouse model of MB. Norrin is a secreted factor that functions as an atypical Wnt by binding to the Frizzled4 (Fzd4) receptor on endothelial cells to activate canonical beta-catenin-mediated Wnt signaling pathway. In the cerebellum, activation of Norrin/Fzd4 signaling is required for the establishment and maintenance of the blood brain barrier (BBB). We have identified a role for Norrin signaling in the stroma as a potent tumor inhibitory signal. Inactivation of Norrin in Ptch+/- mice significantly shortens latency and increases MB incidence. This phenotype is associated with an increased frequency of pre-tumor lesions and their conversion to malignancy. In this context, loss of Norrin signalling in endothelial cells is associated with an accelerated transition to a pro-tumor stroma characterized by vascular permeability, inflammation and angiogenic remodelling. Accordingly, loss of Ndp significantly alters the stromal gene expression signature of established Ptch MB.
Norrin/Frizzled4 signalling in the preneoplastic niche blocks medulloblastoma initiation.
Specimen part
View SamplesMedulloblastoma (MB), a tumor of the cerebellum, is the most common malignant brain tumor in children. One third of all human MB exhibits a gene expression signature of Sonic hedgehog (Shh) signaling. Hedgehog (Hh) pathway inhibitors have shown efficacy in clinical trials for MB, however, tumors develop resistance to these compounds, highlighting the need to identify additional therapeutic targets for treatment. We have identified a role for Norrin signaling in tumor initiation in the Patched (Ptch) mouse model of MB. Norrin is a secreted factor that functions as an atypical Wnt by binding to the Frizzled4 (Fzd4) receptor on endothelial cells to activate canonical beta-catenin-mediated Wnt signaling pathway. In the cerebellum, activation of Norrin/Fzd4 signaling is required for the establishment and maintenance of the blood brain barrier (BBB). We have identified a role for Norrin signaling in the stroma as a potent tumor inhibitory signal. Inactivation of Norrin in Ptch+/- mice significantly shortens latency and increases MB incidence. This phenotype is associated with an increased frequency of pre-tumor lesions and their conversion to malignancy. In this context, loss of Norrin signalling in endothelial cells is associated with an accelerated transition to a pro-tumor stroma characterized by vascular permeability, inflammation and angiogenic remodelling. Accordingly, loss of Ndp significantly alters the stromal gene expression signature of established Ptch MB.
Norrin/Frizzled4 signalling in the preneoplastic niche blocks medulloblastoma initiation.
Specimen part
View SamplesIntravenous Immunoglobulin (IVIg) is widely used as an immunomodulatory therapy. We have recently demonstrated that IVIg protects against airway hyper-reactivity (AHR) and inflammation in mouse models of allergic airway disease (AAD), associated with induction of Foxp3+ regulatory T cells (Treg). Using DEREG (DEpletion of REGulatory T cell) mice, in which endogenous Treg can be ablated with Diphtheria toxin (DTx) treatment, we demonstrate that IVIg generates a de novo population of induced Treg (iTreg) in the absence of endogenous Treg. IVIg-generated iTreg were sufficient for inhibition of ovalbumin-induced AHR in an antigen-driven murine model of AAD. In the absence of endogenous Treg, IVIg failed to confer protection against AHR and airway inflammation. Adoptive transfer of purified IVIg-generated iTreg prior to antigen challenge effectively prevented airway inflammation and AHR in an antigen-specific manner.
Peripherally Generated Foxp3<sup>+</sup> Regulatory T Cells Mediate the Immunomodulatory Effects of IVIg in Allergic Airways Disease.
Specimen part
View SamplesAstrocytes, the most prominent glial cell type in the brain, send specialized processes called endfeet around blood vessels and express a large molecular repertoire regulating the cerebrovascular system physiology. One of the most striking properties of astrocyte endfeet is their enrichment in gap junction protein Connexin 43 and 30 (Cx43 and Cx30) allowing in particular for direct intercellular trafficking of ions and small signaling molecules through perivascular astroglial networks. In this study, we addressed the specific role of Cx30 at the gliovascular interface. Using an inactivation mouse model for Cx30 (Cx30?/?), we showed that absence of Cx30 does not affect blood-brain barrier (BBB) organization and permeability. However, it results in the cerebrovascular fraction, in a strong upregulation of Sgcg encoding g-Sarcoglycan (SG), a member of the Dystrophin-associated protein complex (DAPC) connecting cytoskeleton and the extracellular matrix. The same molecular event occurs in Cx30T5M/T5M mutated mice, where Cx30 channels are closed, demonstrating that Sgcg regulation relied on Cx30 channel functions. We further characterized the cerebrovascular Sarcoglycan complex (SGC) and showed the presence of a-, ß-, d-, ?-, e- and ?- SG, as well as Sarcospan. Altogether, our results suggest that the Sarcoglycan complex is present in the cerebrovascular system, and that expression of one of its members, g-Sarcoglycan, depends on Cx30 channels. As described in skeletal muscles, the SGC may contribute to membrane stabilization and signal transduction in the cerebrovascular system, which may therefore be regulated by Cx30 channel-mediated functions. Overall design: Comparison of 3-month-old Cx30 deleted mice against WT genetic background.
The Sarcoglycan complex is expressed in the cerebrovascular system and is specifically regulated by astroglial Cx30 channels.
No sample metadata fields
View SamplesThe goal is to investigate gene regulation in endometrial stromal cells expressing the Notch ligand Jag1.
Notch ligand-dependent gene expression in human endometrial stromal cells.
Specimen part
View SamplesHuman CD4+CD45RA+CD25- cells were lentivirally transduced with wild-type or mutated (A384T or R397W) FOXP3, or an empty vector (EV). Transduced cells were sorted 14 days post-transduction based on GFP expression, and were restimulated with soluble anti-CD3 (30 ng/mL) and irradiated PBMCs (3x) for 14 more days. Cells were then activated with 0.5 g/ml of phytohemagglutinin (PHA) in the presence or absence of SGF003 (8 g/mL), and total RNA was extracted for microarray analysis. Overall, this study highlights the functional impact of TIP60 in FOXP3-driven Treg biology and provides a novel target for manipulation of human Treg activity.
Suppression by human FOXP3<sup>+</sup> regulatory T cells requires FOXP3-TIP60 interactions.
No sample metadata fields
View SamplesIn an attempt to elucidate the molecular mechanisms underlying the multiple roles of L1 in endothelium, we checked whether manipulating its expression affected the transcriptome of lECs. To this purpose, we compared the gene expression profiles of L1-overexpressing and control lECs by Affymetrix, which revealed a remarkable effect of L1 overexpression on lECs transcriptome.
Endothelial deficiency of L1 reduces tumor angiogenesis and promotes vessel normalization.
Specimen part
View SamplesIncreasing evidence supports a role for altered gene expression in mediating the lasting effects of cocaine on the brain, and recent work has demonstrated the involvement of chromatin modifications in these alterations. However, all such studies to date have been restricted by their reliance on microarray technologies which have intrinsic limitations. Here, we used advanced sequencing methods, RNA-seq and ChIP-seq, to obtain an unprecedented view of cocaine-induced changes in gene expression and associated adaptations in numerous modes of chromatin regulation in the nucleus accumbens, a key brain reward region. We identify unique combinations of chromatin changes, or signatures, that accompany cocaine’s regulation of gene expression, including the dramatic involvement of pre-mRNA alternative splicing in cocaine action. Together, this delineation of the cocaine-induced epigenome in the nucleus accumbens reveals several novel modes of drug regulation, thereby providing new insight into the biological basis of cocaine addiction. More broadly, the combinatorial chromatin and transcriptional approaches that we describe serve as an important resource for the field, as they can be applied to other systems to reveal novel transcriptional and epigenetic mechanisms of neuronal regulation. Overall design: Total RNA was isolated from mouse nucleus accumbens 24 hr after 7 day daily cocaine or saline control ip injection for mRNA sequencing by following illumina RNA seq kit protocol. Another batch of acute cocaine RNA-seq was performed using the same parameters except the treatment group was given 6 days of saline injection followed by 1 day of cocaine injection. The acute cocaine batch serves as control experiments.
Chronic cocaine-regulated epigenomic changes in mouse nucleus accumbens.
No sample metadata fields
View SamplesCocaine-mediated repression of the histone methyltransferase (HMT) G9a has recently been implicated in transcriptional, morphological, and behavioral responses to chronic cocaine administration. Here, using a ribosomal affinity purification approach, we find that G9a repression by cocaine occurs in both Drd1 (striatonigral)- and Drd2 (striatopallidal)-expressing medium spiny neurons (MSNs). Conditional knockout and overexpression of G9a within these distinct cell types, however, reveals divergent behavioral phenotypes in response to repeated cocaine treatment. Our studies further indicate that such developmental deletion of G9a selectively in Drd2 neurons results in the unsilencing of transcriptional programs normally specific to striatonigral neurons, and the acquisition of Drd1-associated projection and electrophysiological properties. This partial striatopallidal to striatonigral switching phenotype in mice indicates a novel role for G9a in contributing to neuronal subtype identity, and suggests a critical function for cell-type specific histone methylation patterns in the regulation of behavioral responses to environmental stimuli.
G9a influences neuronal subtype specification in striatum.
Sex, Specimen part
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