Project description:Microglia are brain immune cells that constantly survey their environment to maintain homeostasis. Enhanced microglial reactivity and proliferation are typical hallmarks of neurodegenerative diseases. Whether specific disease-linked microglial subsets exist during the entire course of neurodegeneration, including the recovery phase, is currently unclear. Taking a single-cell RNA-sequencing approach in a susceptibility gene-free model of nerve injury, we identified a microglial subpopulation that upon acute neurodegeneration shares a conserved gene regulatory profile compared to previously reported chronic and destructive neurodegeneration transgenic mouse models. Our data also revealed rapid shifts in gene regulation that defined microglial subsets at peak and resolution of neurodegeneration. Finally, our discovery of a unique transient microglial subpopulation at the onset of recovery may provide novel targets for modulating microglia-mediated restoration of brain health.
Project description:Microglia are resident myeloid cells of the central nervous system (CNS). Recently, single-cell RNA sequencing (scRNAseq) has enabled description of a disease-associated subtype of microglia (DAM) with a role in neurodegeneration and demyelination. In this study we use scRNAseq to investigate the temporal dynamics of immune cells harvested from the epicenter of traumatic spinal cord injury (SCI). As a consequence of SCI, homeostatic microglia undergo permanent transcriptional re-programming into a subtype of microglia with striking similarities to previoysly reported DAM as well as a distinct microglial state found during development. Using a microglia depletion model we showed that DAM in SCI are derived from homeostatic microglia and strongly enhance recovery of hind limb locomotor function following injury.
Project description:In this study, we used single-cell RNA-sequencing to gain unprecedented insight into the phenotypic heterogeneity and the transcriptional dynamics of microglia cells during the progression of neurodegeneration. Briefly, by using a severe neurodegeneration mouse model with Alzheimer’s-like pathology and phenotypes (CK-p25 model), we surveyed microglia activation by RNA sequencing longitudinally at fine temporal- and single-cell resolution. In summary, our work identified previously unobserved heterogeneity in the response of microglia to neurodegeneration, discovered novel microglia cell states, revealed the trajectory of cellular reprogramming of microglia in response to neurodegeneration, and uncovered the underlying transcriptional programs. These insights into the molecular programs underlying microglia activation provided by our study may pave the way for designing new rational and efficient strategies to treat Alzheimer’s and other neurodegenerative diseases.
Project description:Treatment with activated mesenchymal stem cells increases long-term functional recovery following ischemic stroke via reduction of microglia activation and induction of oligodendrogenesis
Project description:We assessed the roles of repopulating microglia in brain repair using mouse models. In this project, we show that removal of microglia from the mouse brain has little impact on the outcome of TBI but inducing the turnover of these cells through either pharmacologic or genetic approaches can yield a neuroprotective microglial phenotype that profoundly aids recovery. As a part of the experimental approaches, we perform bulk RNA sequencing experiments to unbiasedly profile the transcriptome of repopulating microglia. We identified unique gene signatures from repopulating microglia cells and infer how these cells modulate the microenvironment after TBI.
Project description:The acetylation levels of histones and other proteins change during aging and have been linked to neurodegeneration. Here we show that deletion of the histone acetyltransferase (HAT) co-factor Trrap specifically impairs the function of the transcription factor Sp1, reduces its stability and causes a decrease in histone acetylation at Sp1 target genes. Modulation of Sp1 function by Trrap acts as a hub regulating multiple processes involved in neuron and neural stem cells function and maintenance including microtubule dynamics and the Wnt signaling pathway. Consistently, Trrap conditional mutants exhibit all hallmarks of neurodegeneration including dendrite retraction and axonal swellings, neuron death, astrogliosis, microglia activation, demyelination and decreased adult neurogenesis. Our results uncovered a novel functional network, essential to prevent neurodegeneration, and involving the specific regulation of Sp1 transcription factor and its downstream targets by Trrap-HAT.
Project description:Purpose: RNASeq was used to identify transcriptional signature responsible for the metabolic reprogramming phenotype of microglia in neurodegenerative disease Result: We identified Ppargc1a/Cebpb signaling pathway as a critical axis that controls microglial glycolytic transition during neurodegeneration
Project description:Microglia in the spinal dorsal horn have been implicated in the pathogenesis of neuropathic pain following peripheral nerve injury. We have revently found that CD11c-expressing spinal microglia appear after the development of behavioral pain hypersensitivity following nerve injury and are essential for recovery from neuropathic pain. In order to better understand the gene expression profiles of CD11c-expressing microglia, we performed quantitative bulk RNA sequencing of microglia isolated from mice expressing Venus fluorescent protein under the control of CD11c promoter. We found that CD11c-expressing microglia show distinct gene expression profile compared to CD11c-negative microglia following nerve injury.