Project description:Profiling of transcriptional changes in rat astrocytes when co-cultured with neurons: comparison of astrocytes cultured alone with astrocytes co-cultured with mouse hippocampal neurons. Co-cultured astrocytes are isolated using cold jet, a novel tool for these neuron-glia cultures. Over the last decade, the importance of astrocyte-neuron communication in neuronal development and synaptic plasticity has become increasingly clear. Since neuron-astrocyte interactions represent highly dynamic and reciprocal processes, we hypothesized that at least part of the involved astrocyte genes may be regulated as a consequence of their interactions with maturing neurons. In order to identify such neuron-induced astrocyte genes in vitro, we tested the effectiveness of the ‘cold jet’, a new method for separation of neurons from co-cultured astrocytes. The cold jet method is performed under ice-cold conditions and avoids protease-mediated isolation of astrocytes or time-consuming centrifugation, yielding intact astrocyte mRNA with approximately 90% of neuronal RNA removed. Using this method, we executed genome-wide profiling in which RNA derived from astrocyte-only cultures was compared with astrocyte RNA derived from differentiating neuron-astrocyte co-cultures. Data analysis revealed changes in expression of a large number of mRNAs and biological processes, including novel findings. Thus, cold jet is an efficient method to separate astrocytes from neurons in co-culture, and in this study reveals that neurons induce robust gene-expression changes in co-cultured astrocytes.
Project description:Protein from astrocytes (glial fibrillary acidic protein-positive cells), neurons (beta-III tubulin-positive cells), and unsorted (cell suspension without any enrichment based on astrocyte or neuron markers) from human, post-mortem Alzheimer's disease (AD) and aged-matched non-symptomatic (NS) prefrontal cortex brain samples.
Project description:Little is known about factors that induce stem cells differentiated into astrocyte. Using double cross strategy, we effective narrow down the candidate molecules crucial for astroglial differentiation. By cross comparison the data from transcriptomic and proteomic experiments, we selected 24 candidate genes which might be involved in the neuron differentiation. The 24 genes were further cross compared with Alzheimer disease (AD) database, which regarded as a neuron degenerative database. There were 18 out of 24 candidates showed opposite expression level in our data and AD database. Among them, the combination of Heat Shock Protein 27 (HSP27) and S100 calcium-binding protein A16 (S100A16) showed predominant crucial in neuronal differentiation than other gene combination. We previously showed that the expression level of HSP27 directly related to the glutamatergic neuron differentiation under IBMX induction. In this paper, we found co-silence of HSP27 and S100A16 directly induced PDMCs differentiate into functional glutamatergic neurons and astrocytes while IBMX is no longer required in this process. The resulting astrocyte not only exhibit the classic morphology but also with astrocyte function.
Project description:Astrocyte-to-neuron conversion has developed into a promising avenue for neuronal replacement therapy. Neurons depend critically on mitochondria function and often die by ferroptosis during the conversion process. Here we examined the extent of adequate mitochondrial reprogramming by morphology and proteome analysis. While mitochondria profoundly changed their morphology during Neurogenin2 (Neurog2) – or Achaete-scute homolog 1 (Ascl1)-mediated astrocyte-to-neuron reprogramming, we found neuron-specific mitochondrial proteins, here identified in a comprehensive proteome analysis of isolated mitochondria from primary neurons and astrocytes, to be only partially and at late stages regulated during the process. To improve this, we used dCas9 technology to induce neuron-specific mitochondrial proteins early during reprogramming. This resulted not only in increased conversion efficiency, but also in faster neuronal generation. Taken together, reprogramming mitochondria in a cell type-specific manner has powerful effects on astrocyte-to-neuron conversion, suggesting mitochondria to be a driving force in this process.
Project description:SORL1 is implicated in the pathogenesis of Alzheimer’s disease (AD) through genetic studies. To interrogate the role(s) of SORL1 in human brain cells, SORL1 null iPSCs are differentiated to neuron, astrocyte, microglial, and endothelial cell fates. Loss of SORL1 leads to alterations in both overlapping and distinct pathways across cell types, with the greatest effects in neurons and astrocytes. SORL1 loss induces a neuron-specific reduction in APOE and CLU and altered lipid profiles. Enhancement of retromer-mediated trafficking rescues tau phenotypes observed in SORL1 null neurons but does not rescue APOE levels. Pathway analyses implicate TGF-β/SMAD signaling in SORL1 function, and modulating SMAD signaling in neurons alters APOE RNA levels in a SORL1-dependent manner. Analyses of iPSCs derived from a large cohort reveal a neuron-specific association between SORL1, APOE, and CLU levels, a finding validated in post-mortem brain. These studies provide a mechanistic link between strong genetic risk factors for AD.
Project description:Neurons induce a dramatic transformation in developing astrocytes, causing them to develop a complex stellate morphology resembling their appearance in vivo. However, the transcriptional changes that accompany this transformation are not known, nor are the signalling mechanisms responsible. Similarly, whether synaptic activity controls astrocytic gene expression and whether this leads to altered astrocytic function is unclear. This experiment seeks to investigate this non-cell-autonomously regulated gene expression by co-culturing astrocytes and neurons derived from closely related species (mouse and rat), and separating RNA-seq reads derived from each cell type in silico, thus shedding light on the signalling mechanisms underlying neuron-to-astrocyte communication and the functional consequences for astrocytes.
Project description:To identify the genes directly regulated by H3K9la on a genome-wide scale, we performed CUT&Tag assays using a H3K9la specific antibody in CAL27 and HN30 with or without the lactic acid treatment, and performed CUT&Tag assays using a H3K9la specific antibody in HN30 under hypoxia condition.
Project description:Astrocytes are essential cells of the central nervous system, characterized by dynamic relationships with neurons that range from functional metabolic interactions and regulation of neuronal firing activities, to the release of neurotrophic and neuroprotective factors. In Parkinson’s disease (PD), dopaminergic neurons are a vulnerable population progressively lost during the course of the disease, but the effects of PD on astrocytes and astrocyte-to-neuron communication remains mostly unknown. This study focuses on the effects of the PD-related mutation LRRK2 G2019S in astrocytes, using patient-derived induced pluripotent stem cells. We report the alteration of extracellular vesicle (EV) biogenesis in astrocytes, and we identify the abnormal accumulation of key PD-related proteins within multi vesicular bodies (MVBs). We found that dopaminergic neurons internalize astrocyte-secreted EVs but LRRK2 G2019S EVs are abnormally enriched in the neurites and provide only marginal neurotrophic support to dopaminergic neurons. Thus, dysfunctional astrocyte-to-neuron communication via altered EV biological properties could participate in the progression of PD.
Project description:SORL1 is strongly implicated in the pathogenesis of Alzheimer’s disease (AD) through human genetic studies that point to an association of reduced SORL1 levels with higher risk for AD. To interrogate the role(s) of SORL1 in human brain cells, SORL1 null iPSCs were generated, followed by differentiation to neuron, astrocyte, microglial, and endothelial cell fates. Loss of SORL1 led to alterations in both overlapping and distinct pathways across cell types, with the greatest effects in neurons and astrocytes. Intriguingly, SORL1 loss led to a dramatic neuron-specific reduction in APOE and CLU levels, an increase in the accumulation of lipid droplets and altered lipid profiles. Pathway analysis implicated intracellular transport pathways and TGF-β/SMAD signaling in the function of SORL1 in neurons. Enhancement of retromer-mediated trafficking and autophagy rescued tau phenotypes observed in SORL1 null neurons but did not rescue APOE levels. However, stimulation and inhibition of SMAD signaling in neurons modulated APOE RNA levels in a SORL1-dependent manner. Further, analyses of iPSCs derived from a human aging cohort revealed a neuron-specific linear correlation between SORL1 and APOE RNA and protein levels, a finding validated in human post-mortem brain. These studies provide a mechanistic link between two of the strongest genetic risk factors for AD.