Project description:This study examines a co-culture model of human iPSC-derived cholinergic neurons with glioblastoma (GBM) cells derived from GBM organoids (GBOs; UP-10072). To examine transcriptional regulation of GBM cells by cholinergic neurons, we performed scRNAseq of a set of distinct conditions: 1) cholinergic neurons only; 2) GBM cells only; 3) GBM cells treated with conditioned medium from neurons; 4) direct GBM cell-cholinergic neuron co-cultures.
Project description:This study explores the effect of long-range cholinergic input on glioblastoma (GBM) progression based on systematically mapping neuron-glioma connectivity via monosynaptic rabies virus tracing. To address the mechanism of cholinergic and glutamate inputs lead to increased GBM cell proliferation, we examined transcriptomic changes in patient-derived GBM cells at both early (3h) and chronic (24h) time points following brief exposure to glutamate, Cev, or their combination.
Project description:Circadian clocks are encoded by a transcription-translation feedback loop that aligns physiological processes with the solar cycle. Previous work linking the circadian clock to the regulation of RNA-binding proteins (RBPs) provides a foundation for the vital examination of their mechanistic connections in the context of amyotrophic lateral sclerosis (ALS)—a fatal neurodegenerative disease commonly marked by disrupted RBP function. Here, we reveal that the spinal cord cholinergic neuron rhythmic transcriptome is enriched for genes associated with ALS and other neurodegenerative diseases. We show that there is time-of-day-dependent expression of ALS-linked RBP transcripts and rhythmic alternative splicing of genes involved in microtubule cytoskeleton organization, intracellular trafficking, and synaptic function. Through in silico analysis of RNA sequencing data from sporadic ALS patients, we find that gene expression profiles altered in disease correspond with rhythmic gene networks. Finally, we report that clock disruption through cholinergic neuron-specific deletion of clock activator BMAL1 increases neurodegeneration and drives time-of-day-dependent alternative splicing of RNA processing genes. Our results establish a role for the cholinergic neuron circadian clock in RNA metabolism and mediating neurodegeneration.
Project description:Circadian clocks are encoded by a transcription-translation feedback loop that aligns physiological processes with the solar cycle. Previous work linking the circadian clock to the regulation of RNA-binding proteins (RBPs) provides a foundation for the vital examination of their mechanistic connections in the context of amyotrophic lateral sclerosis (ALS)—a fatal neurodegenerative disease commonly marked by disrupted RBP function. Here, we reveal that the spinal cord cholinergic neuron rhythmic transcriptome is enriched for genes associated with ALS and other neurodegenerative diseases. We show that there is time-of-day-dependent expression of ALS-linked RBP transcripts and rhythmic alternative splicing of genes involved in microtubule cytoskeleton organization, intracellular trafficking, and synaptic function. Through in silico analysis of RNA sequencing data from sporadic ALS patients, we find that gene expression profiles altered in disease correspond with rhythmic gene networks. Finally, we report that clock disruption through cholinergic neuron-specific deletion of clock activator BMAL1 increases neurodegeneration and drives time-of-day-dependent alternative splicing of RNA processing genes. Our results establish a role for the cholinergic neuron circadian clock in RNA metabolism and mediating neurodegeneration.
Project description:The complexity of events associated with age-related memory loss (ARML) cannot be overestimated. The problem is further complicated by the enormous diversity of neurons in the CNS and even synapses of one neuron within a neural circuit. Large-scale single-neuron analysis is not only challenging but mostly impractical for any model currently used in ARML. We simply do not know: do all neurons and synapses age differently or are some neurons (or synapses) more resistant to aging than others? What is happening in any given neuron while it undergoes “normal” aging? What are the genomic changes that make aging apparently irreversible? What would be the balance between neuron-specific vs global genome-wide changes in aging? In the proposed paper we address these questions and develop a new model to study the entire scope of genomic and epigenomic regulation in aging at the resolution of single functionally characterized cells and even cell compartments. In particular, the mollusc Aplysia californica has been implemented as a powerful paradigm in addressing fundamental questions of the neurobiology of aging. The proposed manuscript will consist of four parts. First, we will provide an introduction to Aplysia as a representative of the largest superclade of bilaterian animals (Lophotrochozoa). Aplysia has a short lifespan of 220-300 days with a well-characterized life cycle and characterized phenomenology of aging. Most importantly, Aplysia possess the largest nerve cells in the entire animal kingdom (only eggs are larger); these cells can be uniquely identified and mapped in terms of their well-defined interactions with other neurons forming relatively simpler neural circuits underlying several stereotypic and learned behaviors. Second, we have identified in Aplysia more that a hundred neurological- and age-related genes that were lost in other established invertebrate models (such as Drosophila and C. elegans). The proposed long-term regulatory age-related mechanisms include a high level of conservation among many epigenetic processes known to be lost in nematodes and flies with extremely short lifecycles and particularly derived genomes. We also identify and cloned more than 30 evolutionarily conserved homologs of genes involved in Alzheimer’s, Parkinson’s and Huntington’s diseases as well as age-related hormones. Third, we performed genome-wide analysis of expression patterns of more than 55,000 unique transcripts by comparing two different identified cholinergic neurons (R2 and LPl1) among young and aged animals. This direct single neuron genomic analysis indicates that there are significant cell-specific changes in gene-expression profiles as a function of aging. We estimated that only ~10-20% of genes that are differently expressed in the aging brain are common for all neuronal types - the remaining 80% are neuron-specific (i.e. found in aging neurons of one but not another type). The list of “common aging genes” includes components of insulin growth factor pathways, cell bioenergetics, telomerase-associated proteins, antioxidant enzymes, water channels and estrogen receptors. The rest were neuron-specific gene products (including apoptosis-related proteins, Alzheimer-related genes, growth factors and their receptors, ionic channels, transcription factors and more than 120 identified proteins known to be involved in neurodevelopment and synaptogenesis). Surprisingly, even two different identified cholinergic motoneurons age differently and each of them has a unique subset of genes differentially expressed in older animals. Fourth, we showed that the activity of the entire genome and associated epigenomic modifications (e.g. DNA methylation, histone dynamics) can be efficiently monitored within a single Aplysia neuron and can be modified as a function of aging in a neuron-specific manner including selective histones and histone-modifying enzymes and DNA methylation-related enzymes. This genome-wide analysis of aging allows us to propose novel mechanisms of active DNA demethylation and cell-specific methylation as well as regional relocation of RNAs as three key processes underlying age-related memory loss. These mechanisms tune the dynamics of long-term chromatin remodeling, control weakening and the loss of synaptic connections in aging. At the same time, our genomic tests revealed evolutionarily conserved gene clusters in the Aplysia genome associated with senescence and regeneration (e.g. apoptosis- and redox- dependent processes, insulin signaling, etc.). This is a reference design experiment with all samples being compared to one CNS from Aplysia. Two cholinergic neurons (R2 and LPl1), two ages (young and old), two arrays (AAA and DAA), three biological replicates each sample type. Two direct comparison experiments were also performed. One with young and old abdominal ganglion and the other with young and old R2.
Project description:We performed ATAC-seq on iPSC-derived hypothalamic arcuate-like neuron cells to identify putative regulatory elements. All samples were derived from the same individual and from the same differentiation/cell line but ATAC-seq was performed in 3 separate experiments (3 technical replicates).
Project description:The nucleus basalis, also known as the nucleus basalis of Meynert (nbM), which is considered to be one of the major cholinergic output of basal forebrain, have been found to dynamically modulate activity in the cortex. Dysfunction of nucleus basalis-cortical cholinergic circuit led to cognitive impairment, such as Alzheimer's disease (AD) and Down syndrome (DS). Human nucleus basalis cholinergic neurons derived from human pluripotent stem cells provide powerful tools to study cholinergic neurons-associated diseases and cell therapy. Previous studies reported the generation of 2D human basal forebrain cholinergic neurons which failed to recapitulate the spatial organization, cellular diversity, and crosstalk between different regions. Therefore, a better model to recapitulate human nucleus basalis and cholinergic projections in nbM-cortical is desired. Here we developed a approach for differentiating human pluripotent stem cells into nucleus basalis of Meynert organoids (hnbMOs). We reconstructed hnbM-cortex cholinergic projection by transplanting hnbMOs into immunodeficiency mice to construct chimeric brains and coculturing with human fetal brain. Then we fused hnbMOs with cerebral cortex organoids (hCOs) to form hnbMO-hCO assembloids. We validate the structural and functional connectivity of basal forebrain cholinergic neurons to the cortex in assembloids. An assembloid-chimeric brain was constructed innovatively by transplanting corresponding organoids in the cortex and nbM region to establish a complete human cholinergic projection system. Futhermore, we identified the defects in projection of cholinergic neurons at the morphological and transcriptomic level in Down syndrome patient iPSC-derived assembloids as well as Down syndrome fetal brain tissue. Our work establishes new approach for the study of neurological disorders associated with nbM and nbM-cortical cholinergic neuron circuit.
Project description:The results provide significant insights into the role of Grin2D in regulating the secretion of neurotrophic factors that promote neuritogenesis. Transcriptomic analysis of orthotopically transplanted PDAC cancer cells with a knockout of the NMDA receptor subunit Grin2D, along with dorsal root ganglia (T8–T12) innervating the pancreas, strongly supports this conclusion. Furthermore, RNA-Seq analysis of tumor and ganglion biopsies from PDAC patients was performed to validate the identified gene candidates in a human context. This study tested the hypothesis that neuronal glutamate drives pancreatic cancer progression via glutamate-mediated GluN2D signaling at the cancer-neuron pseudo-synapses.