Project description:The mammalian brain is heterogeneous, containing billions of neurons and trillions of synapses forming various neural circuitries, through which sense, movement, thought, and emotion are generated. The cellular heterogeneity of the brain has made it difficult to study the molecular logic of neural circuitry wiring, pruning, activation, and plasticity, until recently, transcriptome analyses with single-cell resolution makes decoding of gene regulatory networks underlying aforementioned circuitry properties possible. Here, we report success in performing both electrophysiological and whole-genome transcriptome analyses on single human neurons in culture. Using Weighted Gene Coexpression Network Analyses (WGCNA), we identified gene clusters highly correlated with neuronal maturation judged by electrophysiological characteristics. A tight link between neuronal maturation and genes involved in ubiquitination and mitochondrial function was revealed. Moreover, we identified a list of candidate genes, which could potentially serve as biomarkers for neuronal maturation. Coupled electrophysiological recording and single-cell transcriptome analysis will serve as powerful tools in the future to unveil molecular logics for neural circuitry functions.
Project description:The mammalian neocortex is a layered sheet of neural tissue that mediates complex cognitive processes including perception and cognition. Despite its importance, we still lack detailed knowledge of the cellular components of the neocortex. Integrating morphological, electrophysiological and molecular classification schemes into a common framework for defining cell types is challenging due to the limited scope of most single-cell analyses. Here, we developed a protocol for high-throughput electrophysiological and transcriptomic analysis of single neurons that combines whole-cell recordings and single-cell RNA-sequencing, which we call Patch-seq. Using this approach, we fully characterized the electrophysiological and molecular profiles of ~50 neocortical neurons, and show that gene expression patterns can be used to infer the morphological and physiological properties of individual neurons and their corresponding cell type. Our results shed light on the molecular underpinnings of neuronal diversity and demonstrate a path forward for comprehensive cell type characterization in the nervous system.
Project description:This experiment aimed to investigate whether exosomess released by IPSC-cardiomyocytes during hypoxia can positively influence cardiac electrophysiology and miRNA expression during hypoxic stress. A multielectrode array (MEA) system was used as an in vitro method of recording real-time cardiac electrophysiological activity, highlighting the biological effects facilitated by exosomes. Additionally, miRNA-sequencing was performed to compare miRNA expressions in exosome-preconditioned and non-preconditioned IPSC-cardiomyocytes, elucidating important modulators of cardiac electrophysiology.
Project description:We performed brain bulk RNA-seq aiming to study how microglia TREM2-WT or TREM2-R47H expression affect the overall brain transcriptomic profiles. Using WGCNA gene network analysis, we found the presynaptic transmission pathway was dysregulated after TREM2-R47H expression, not TREM2-WT. This finding was consistent with the impaired presynaptic transmission detected by electrophysiological recording in TREM2-R47H expressing mice. In addition, dysregulated circadian pathways were also identified in TREM2-R47H mice, not in TREM2-WT mice. Altogether, our bulk RNA-seq results provide additional evidence at transcriptomics level that TREM2-R47H expression in microglia affects neuronal functions and brain networks.
Project description:Neurons derived from human pluripotent stem cells (hPSCs) are a remarkable tool for modeling human neural development and diseases. However, it remains largely unknown whether the hPSC-derived neurons can be functionally coupled with their target tissues in vitro, which is essential for understanding inter-cellular physiology and further translational studies. Here, we demonstrate that hPSC-derived sympathetic neurons can be obtained from hPSCs and that the resulting neurons form physical and functional connections with cardiac muscle cells. By use of multiple hPSC reporter lines, we recapitulated human autonomic neuron development in vitro, and successfully isolated PHOX2B::eGFP+ neurons exhibiting sympathetic marker expression, electrophysiological properties, and norepinephrine secretion. With pharmacological and optogenetic manipulations, the PHOX2B::eGFP+ neurons controlled the beating rates of cardiomyocytes, and their physical interaction led to neuronal maturation. Our study lays a foundation for the specification of human sympathetic neurons and for the hPSC-based neuronal control of end organs in a dish. Using the four genetic reporter systems (OCT4::eGFP, SOX10::eGFP, ASCL1::eGFP, and PHOX2B::eGFP reporter hESC lines), we were able to purify discrete cell populations at four differentiation stages, recapitulating the sympathoadrenal differentiation process in vitro with purified and defined populations in four specific differentiation stages. We performed transcriptome analysis of OCT4::eGFP+ cells (3 biological replicates, representing undifferentiated hESCs), SOX10::eGFP+ cells (3 biological replicates, multi-potent neural crest), ASCL1::eGFP+ cells (3 biological replicates, putative sympathoadrenal progenitors), and PHOX2B::eGFP+ cells (2 biological replicates, putative sympathetic neuronal precursors).
Project description:The effect of neuronal activity on blood-brain barrier function and whether it plays a role in plasticity in the healthy brain remains unclear. We show that neuronal activity induces modulation of microvascular permeability in the healthy brain and that it has a role in local network reorganization. Combining simultaneous electrophysiological recording and vascular imaging with transcriptomic analysis in rats, and functional and BBB-mapping MRI in human subjects we show that prolonged stimulation of the limb induces a focal increase in BBB permeability in the corresponding somatosensory cortex that is associated with long-term synaptic plasticity. We further show that the increased microvascular permeability depends on neuronal activity and involves caveolae-mediated transcytosis and transforming growth factor beta signaling. Our results reveal a role of BBB modulation in cortical plasticity in the healthy brain, highlighting the importance of neurovascular interactions for sensory experience and learning.