Understanding the mechanisms that specify neuronal subtypes is important to unravel the complex mechanisms of neuronal circuit assembly. Here we have identified a novel role for the transcription factor AP2 in progenitor and neuronal subtype specification in the cerebral cortex. Conditional deletion of AP2 causes misspecification of basal progenitors starting at
AP2gamma regulates basal progenitor fate in a region- and layer-specific manner in the developing cortex.
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View SamplesThe choroid plexuses (ChPs) are the main regulators of cerebrospinal fluid (CSF) composition and thereby also control the composition of a principal source of signaling molecules that is in direct contact with neural stem cells in the developing brain. The regulators of ChP development mediating the acquisition of a fate that differs from the neighboring neuroepithelial cells are poorly understood. Here, we demonstrate in mice a crucial role for the transcription factor Otx2 in the development and maintenance of ChP cells. Deletion of Otx2 by the Otx2-CreERT2 driver line at E9 resulted in a lack of all ChPs, whereas deletion by the Gdf7-Cre driver line affected predominately the hindbrain ChP, which was reduced in size, primarily owing to an increase in apoptosis upon Otx2 deletion. Strikingly, Otx2 was still required for the maintenance of hindbrain ChP cells at later stages when Otx2 deletion was induced at E15, demonstrating a central role of Otx2 in ChP development and maintenance. Moreover, the predominant defects in the hindbrain ChP mediated by Gdf7-Cre deletion of Otx2 revealed its key role in regulating early CSF composition, which was altered in protein content, including the levels of Wnt4 and the Wnt modulator Tgm2. Accordingly, proliferation and Wnt signaling levels were increased in the distant cerebral cortex, suggesting a role of the hindbrain ChP in regulating CSF composition, including key signaling molecules. Thus, Otx2 acts as a master regulator of ChP development, thereby influencing one of the principal sources of signaling in the developing brain, the CSF.
The transcription factor Otx2 regulates choroid plexus development and function.
Sex
View SamplesAstrocytes react to brain injury in a heterogeneous manner with only a subset resuming proliferation and acquiring in vitro neural stem cell properties. In order to identify novel regulators of this astrocyte subset, we performed a genome-wide expression analysis of reactive astrocytes isolated 5 days after stab wound injury from the adult mouse cerebral cortex. The expression pattern was compared with astrocytes from normal cortex and adult neural stem cells isolated from the sub-ependymal zone (GSE18765). These comparisons revealed a set of genes up-regulated both in neurogenic neural stem cells and reactive astrocytes, including the lectins Galectin-1 and -3. These results, as well as the pattern of Galectin expression in the lesioned brain, led us to examine the functional significance of these lectins in brains of Galectin-1/3 double-knockout mice.
Astrocyte reactivity after brain injury-: The role of galectins 1 and 3.
Sex, Specimen part, Treatment, Time
View SamplesIn a transgenic mouse model of Alzheimer disease (AD), cleavage of the amyloid precursor protein (APP) by the -secretase ADAM10 prevented amyloid plaque formation and alleviated cognitive deficits. Furthermore, there was a positive influence of ADAM10 over-expression on neurotransmitter-specific formation of synapses and on synaptic plasticity.
Differential gene expression in ADAM10 and mutant ADAM10 transgenic mice.
Sex, Age
View SamplesChronic obstructive pulmonary disease (COPD) is a heterogenous respiratory disease mainly caused by smoking. Respiratory infections constitute a major risk factor for acute worsening of COPD symptoms or COPD exacerbation. Mitochondrial functionality, which is crucial for the execution of physiologic functions of metabolically active cells, is impaired in airway epithelial cells (AECs) of COPD patients as well as smokers. However, the potential contribution of mitochondrial dysfunction in AECs to progression of COPD, infection-triggered exacerbations in AECs and a potential mechanistic link between mitochondrial and epithelial barrier dysfunction is unknown to date. In this study, we used an in vitro COPD exacerbation model based on AECs exposed to cigarette smoke extract (CSE) followed by infection with Streptococcus pneumoniae (Sp). The levels of oxidative stress, as an indicator of mitochondrial stress were quantified upon CSE and Sp. The expression of proteins associated with mitophagy, mitochondrial content and biogenesis as well as mitochondrial fission and fusion was quantified upon CSE and Sp. Transcriptional AEC profiling was performed to identify the potential changes in innate immune pathways and correlate them with mitochondrial function. We found that CSE exposure substantially altered mitochondrial function in AECs by suppressing mitochondrial complex protein levels, reducing mitochondrial membrane potential and increasing mitochondrial stress and mitophagy. Moreover, CSE-induced mitochondrial dysfunction correlated with reduced enrichment of genes involved in apical junctions and innate immune responses to Sp, particularly type I interferon responses. Together, our results demonstrated that CSE-induced mitochondrial dysfunction may contribute to impaired innate immune responses to Sp and may thus trigger COPD exacerbation.
Cigarette Smoke Extract Disturbs Mitochondria-Regulated Airway Epithelial Cell Responses to Pneumococci.
Specimen part, Cell line, Treatment
View SamplesThe respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica (Bb) as the underlying model to comprehensively address effects on subsequent immune responses. Persistent carriage was associated with the stimulation of Bordetella-specific CD4+, CD8+ and CD4+CD25+Foxp3+ T cell responses and broad transcriptional activation was observed in CD4+CD25+ T cells. Importantly, transfer of lymphocytes from persistent carriers to acutely B. bronchiseptica infected mice resulted in a significantly increased bacterial burden in the recipients upper respiratory tract. In contrast, we found that B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. At the same time, vaccination and influenza A virus infection were unaffected. These data demonstrate that there are significant immune modulatory processes triggered by persistent B. bronchiseptica carriage that differentially affect subsequent immune responses. Thereby our results demonstrate the complexity of immune regulation induced by persistent bacterial carriage in the respiratory tract that can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.
No associated publication
Specimen part
View SamplesAlthough mast cells elicit proinflammatory and type I IFN responses upon VSV infection, in response to L.monocytogenes (L.m) or S. Typhimurium (S.t), such cells elicit a transcriptional program devoid of type I IFN response.
Mast cells elicit proinflammatory but not type I interferon responses upon activation of TLRs by bacteria.
Specimen part
View SamplesThe Rift Valley Fever (RVF) is an arthropod-borne disease present in several countries of Africa and Middle East. It is caused by RVF virus which can infect both humans and animals. In humans, it leads to various manifestations including hepatitis, encephalitis and death, while in domestic animals it usually causes miscarriage in pregnant females and it is often fatal for the newborn. Not all people or animal infected by the virus present the same disease. Some patients exhibit unapparent or moderate febrile reactions, while others develop severe symptoms. This observation suggests that host genetic factors play a role in controlling the outcome of infection. In this work, we compare the response of two different inbred strains of mice, MBT/Pas and BALB/cByJ, to infection with RVF virus. These strains exhibit different profiles of susceptibility to RVF virus infection. Indeed, MBT/Pas mice rapidly develop high viraemia and die soon after infection, while BALB/cByJ mice have a lower viraemia and die later. Interestingly, mouse embryonic fibroblasts (MEFs) obtained from MBT/Pas foetuses allows higher viral production than BALB/cByJ MEFs.
A new mouse model reveals a critical role for host innate immunity in resistance to Rift Valley fever.
Specimen part
View SamplesTo acquire more information regarding the local immune events during the different phases of S. aureus infection, gene profiling using microarray technology was used to identify host genes whose expression is substantively altered in the kidneys during the acute (T2) and persistent phase of infection (T28). Genes associated with the distinct transcript profiles were identified by comparing the relative abundance of transcripts at 2 days (acute) and 28 days (persistent) of infection to their abundance in the kidneys of uninfected control animals (CTL).
The dynamics of T cells during persistent Staphylococcus aureus infection: from antigen-reactivity to in vivo anergy.
Specimen part
View SamplesRole for naturally occurring CD4+CD25+Foxp3+ regulatory T cells (nTregs) in counterbalancing this process. Using a transgenic murine model for autoimmune-mediated lung disease, we demonstrated that, despite pulmonary inflammation, lung-specific CD8+ T cells can reside quiescently in close proximity to self-antigen. Whereas self-reactive CD8+ T cells in the inflamed lung and lung-draining lymph nodes down-regulated the expression of effector molecules, those located in the spleen appeared to be partly antigen-experienced and displayed a memory-like phenotype. Since ex vivo-reisolated self-reactive CD8+ T cells were very well capable to respond to the antigen in vitro, we investigated a possible contribution of nTregs to the immune control over autoaggressive CD8+ T cells in the lung.
CD4+CD25+Foxp3+ regulatory T cells are dispensable for controlling CD8+ T cell-mediated lung inflammation.
Specimen part
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