Project description:Smad2/3 are canonical effector of TGFb signaling. This pathway is essential for microglial differentiation. We isolated Smad2/3-deficient microglia from mice and determined their transcriptional profiles. By comparing to control microglia, we observed changes in the expression of genes involved in macrophage function and lipid metabolism, which is consistent with the importance of these processes in microglial homeostasis. since microglia lacking Smad2/3 show an activated phenotype, these results provide insights into the transcriptional regulation of microglial function.
Project description:Microglia contribute to maintaining brain homeostasis by interacting with neurons and macroglial cells through different signaling molecules. Here, we investigate the transcriptional profile of microglia lacking TGFbeta signaling given by inactivation of the Tgfbr2 gene, at three different stages of development. These microglia show a signature consistent with increased activation and impaired maturation, representing a state commonly associated with neurological pathologies.
Project description:The role of microglia cells in Alzheimer’s disease (AD) is well recognized, however their molecular and functional diversity remain unclear. Here we isolated amyloid plaque-containing (using labelling with methoxy–XO4, XO4+) and non-containing (XO4-) microglia from an AD mouse model. Transcriptomics analysis identified different transcriptional trajectories in ageing and AD mice. XO4+ microglial transcriptomes demonstrated dysregulated expression of genes associated with late onset AD. We further showed that the transcriptional program associated with XO4+ microglia from mice is present in a subset of human microglia isolated from brains of individuals with AD. XO4- microglia displayed transcriptional signatures associated with accelerated ageing and contained more intracellular post-synaptic material than XO4+ microglia, despite reduced active synaptosome phagocytosis. We identified HIF1α as potentially regulating synaptosome phagocytosis in vitro using primary human microglia, and BV2 mouse microglial cells. Together these findings provide insight into molecular mechanisms underpinning the functional diversity of microglia in AD.
Project description:During development, key processes are orchestrated by Nodal/Activin signaling via SMAD2. Interplay between the SMADs, co-factors and chromatin determines cell-type specific responses, but the sequence of events underpinning SMAD2-mediated transcription is unknown. We performed RNA-and ChIP-sequencing for SMAD2, RNA Polymerase II and various histone modifications in different signaling states. Integration of these data reveals a dynamic transcriptional network downstream of Nodal/Activin signaling regulated by SMAD2 acting via multiple mechanisms. Upon ligand stimulation, SMAD2 can bind to pre-acetylated nucleosome-depleted sites, but also to unacetylated closed chromatin, where it induces nucleosome displacement and histone acetylation. Importantly, SMAD2 binding is highly dynamic and does not directly correlate with the transcriptional kinetics of target genes. Moreover, we show that SMAD2 initiates transcription by inducing RNA Polymerase II recruitment. We therefore define new paradigms for SMAD2-dependent transcription and provide a framework to understand how cells correctly execute gene expression programs in response to Nodal/Activin signaling.
Project description:This paper demonstrates that whereas SOX2+ cells in HDB are highly susceptible to ZKV, SOX2+ primary GBM samples exhibit moderate to high resistance to infection. Expression profiling revealed an innate immune signature due to microglia infiltration in highly resistant GBM samples that was lacking in HDB. This data was generated to proflile the transcriptional response to microglia-secreted factors in stem cells from glioma cell lines and human developing brain. We find that Interferon-stimulated genes are the main targets upregulated in response to microglia conditioned media exposure.