技术资料

Despite major advances in the pathophysiological understanding of peripheral nerve damage,the treatment of nerve injuries still remains an unmet medical need. Nerve guidance conduits present a promising treatment option by providing a growth-permissive environment that 1) promotes neuronal cell survival and axon growth and 2) directs axonal extension. To this end,we designed an electrospun nerve guidance conduit using a blend of polyurea and poly-caprolactone with both biochemical and topographical cues. Biochemical cues were integrated into the conduit by functionalizing the polyurea with RGD to improve cell attachment. Topographical cues that resemble natural nerve tissue were incorporated by introducing intraluminal microchannels aligned with nanofibers. We determined that electrospinning the polymer solution across a two electrode system with dissolvable sucrose fibers produced a polymer conduit with the appropriate biomimetic properties. Human neural stem cells were cultured on the conduit to evaluate its ability to promote neuronal growth and axonal extension. The nerve guidance conduit was shown to enhance cell survival,migration,and guide neurite extension. View Publication

Synaptic plasticity is mediated by the dynamic localization of proteins to and from synapses. This is controlled,in part,through activity-induced palmitoylation of synaptic proteins. Here we report that the ability of the palmitoyl-acyl transferase,DHHC5,to palmitoylate substrates in an activity-dependent manner is dependent on changes in its subcellular localization. Under basal conditions,DHHC5 is bound to PSD-95 and Fyn kinase,and is stabilized at the synaptic membrane through Fyn-mediated phosphorylation of a tyrosine residue within the endocytic motif of DHHC5. In contrast,DHHC5's substrate,δ-catenin,is highly localized to dendritic shafts,resulting in the segregation of the enzyme/substrate pair. Neuronal activity disrupts DHHC5/PSD-95/Fyn kinase complexes,enhancing DHHC5 endocytosis,its translocation to dendritic shafts and its association with δ-catenin. Following DHHC5-mediated palmitoylation of δ-catenin,DHHC5 and δ-catenin are trafficked together back into spines where δ-catenin increases cadherin stabilization and recruitment of AMPA receptors to the synaptic membrane. View Publication

Rett syndrome (RTT) is a severe neurodevelopmental disorder associated with mutations in either MECP2,CDKL5 or FOXG1. The precise molecular mechanisms that lead to the pathogenesis of RTT have yet to be elucidated. We recently reported that expression of GluD1 (orphan glutamate receptor $\$-1 subunit) is increased in iPSC-derived neurons obtained from patients with mutations in either MECP2 or CDKL5. GluD1 controls synaptic differentiation and shifts the balance between excitatory and inhibitory synapses toward the latter. Thus,an increase in GluD1 might be a critical factor in the etiology of RTT by affecting the excitatory/inhibitory balance in the developing brain. To test this hypothesis,we generated iPSC-derived neurons from FOXG1(+/-) patients. We analyzed mRNA and protein levels of GluD1 together with key markers of excitatory and inhibitory synapses in these iPSC-derived neurons and in Foxg1(+/-) mouse fetal (E11.5) and adult (P70) brains. We found strong correlation between iPSC-derived neurons and fetal mouse brains,where GluD1 and inhibitory synaptic markers (GAD67 and GABA AR-$\$1) were increased,whereas the levels of a number of excitatory synaptic markers (VGLUT1,GluA1,GluN1 and PSD-95) were decreased. In adult mice,GluD1 was decreased along with all GABAergic and glutamatergic markers. Our findings further the understanding of the etiology of RTT by introducing a new pathological event occurring in the brain of FOXG1(+/-) patients during embryonic development and its time-dependent shift toward a general decrease in brain synapses. View Publication

Fibroblasts from patients with Type I bipolar disorder (BPD) and their unaffected siblings were obtained from an Old Order Amish pedigree with a high incidence of BPD and reprogrammed to induced pluripotent stem cells (iPSCs). Established iPSCs were subsequently differentiated into neuroprogenitors (NPs) and then to neurons. Transcriptomic microarray analysis was conducted on RNA samples from iPSCs,NPs and neurons matured in culture for either 2 weeks (termed early neurons,E) or 4 weeks (termed late neurons,L). Global RNA profiling indicated that BPD and control iPSCs differentiated into NPs and neurons at a similar rate,enabling studies of differentially expressed genes in neurons from controls and BPD cases. Significant disease-associated differences in gene expression were observed only in L neurons. Specifically,328 genes were differentially expressed between BPD and control L neurons including GAD1,glutamate decarboxylase 1 (2.5 fold) and SCN4B,the voltage gated type IV sodium channel beta subunit (-14.6 fold). Quantitative RT-PCR confirmed the up-regulation of GAD1 in BPD compared to control L neurons. Gene Ontology,GeneGo and Ingenuity Pathway Analysis of differentially regulated genes in L neurons suggest that alterations in RNA biosynthesis and metabolism,protein trafficking as well as receptor signaling pathways may play an important role in the pathophysiology of BPD. View Publication

X-linked dystonia-parkinsonism (XDP) is a hereditary neurodegenerative disorder involving a progressive loss of striatal medium spiny neurons. The mechanisms underlying neurodegeneration are not known,in part because there have been few cellular models available for studying the disease. The XDP haplotype consists of multiple sequence variations in a region of the X chromosome containingTAF1,a large gene with at least 38 exons,and a multiple transcript system (MTS) composed of five unconventional exons. A previous study identified an XDP-specific insertion of a SINE-VNTR-Alu (SVA)-type retrotransposon in intron 32 ofTAF1,as well as a neural-specific TAF1 isoform,N-TAF1,which showed decreased expression in post-mortem XDP brain compared with control tissue. Here,we generated XDP patient and control fibroblasts and induced pluripotent stem cells (iPSCs) in order to further probe cellular defects associated with this disease. As initial validation of the model,we compared expression ofTAF1and MTS transcripts in XDP versus control fibroblasts and iPSC-derived neural stem cells (NSCs). Compared with control cells,XDP fibroblasts exhibited decreased expression ofTAF1transcript fragments derived from exons 32-36,a region spanning the SVA insertion site. N-TAF1,which incorporates an alternative exon (exon 34'),was not expressed in fibroblasts,but was detectable in iPSC-differentiated NSCs at levels that were ∼threefold lower in XDP cells than in controls. These results support the previous findings that N-TAF1 expression is impaired in XDP,but additionally indicate that this aberrant transcription might occur in neural cells at relatively early stages of development that precede neurodegeneration. View Publication

Background: Huntington's disease (HD) is an incurable hereditary neurodegenerative disorder,which manifests itself as a loss of GABAergic medium spiny (GABA MS) neurons in the striatum and caused by an expansion of the CAG repeat in exon 1 of the huntingtin gene. There is no cure for HD,existing pharmaceutical can only relieve its symptoms. Results: Here,induced pluripotent stem cells were established from patients with low CAG repeat expansion in the huntingtin gene,and were then efficiently differentiated into GABA MS-like neurons (GMSLNs) under defined culture conditions. The generated HD GMSLNs recapitulated disease pathology in vitro,as evidenced by mutant huntingtin protein aggregation,increased number of lysosomes/autophagosomes,nuclear indentations,and enhanced neuronal death during cell aging. Moreover,store-operated channel (SOC) currents were detected in the differentiated neurons,and enhanced calcium entry was reproducibly demonstrated in all HD GMSLNs genotypes. Additionally,the quinazoline derivative,EVP4593,reduced the number of lysosomes/autophagosomes and SOC currents in HD GMSLNs and exerted neuroprotective effects during cell aging. Conclusions: Our data is the first to demonstrate the direct link of nuclear morphology and SOC calcium deregulation to mutant huntingtin protein expression in iPSCs-derived neurons with disease-mimetic hallmarks,providing a valuable tool for identification of candidate anti-HD drugs. Our experiments demonstrated that EVP4593 may be a promising anti-HD drug. [ABSTRACT FROM AUTHOR] View Publication

The derivation of astrocytes from human pluripotent stem cells is currently slow and inefficient. We demonstrate that overexpression of the transcription factors SOX9 and NFIB in human pluripotent stem cells rapidly and efficiently yields homogeneous populations of induced astrocytes. In our study these cells exhibited molecular and functional properties resembling those of adult human astrocytes and were deemed suitable for disease modeling. Our method provides new possibilities for the study of human astrocytes in health and disease. View Publication

The human brain is composed of a complex assembly of about 171 billion heterogeneous cellular units (86 billion neurons and 85 billion non-neuronal glia cells). A comprehensive description of brain cells is necessary to understand the nervous system in health and disease. Recently,advances in genomics have permitted the accurate analysis of the full transcriptome of single cells (scRNA-seq). We have built upon such technical progress to combine scRNA-seq with patch-clamping electrophysiological recording and morphological analysis of single human neurons in vitro. This new powerful method,referred to as Patch-seq,enables a thorough,multimodal profiling of neurons and permits us to expose the links between functional properties,morphology,and gene expression. Here,we present a detailed Patch-seq protocol for isolating single neurons from in vitro neuronal cultures. We have validated the Patch-seq whole-transcriptome profiling method with human neurons generated from embryonic and induced pluripotent stem cells (ESCs/iPSCs) derived from healthy subjects,but the procedure may be applied to any kind of cell type in vitro. Patch-seq may be used on neurons in vitro to profile cell types and states in depth to unravel the human molecular basis of neuronal diversity and investigate the cellular mechanisms underlying brain disorders. View Publication

Dynamics of GABAergic synaptic components have been studied previously over milliseconds to minutes,revealing mobility of postsynaptic scaffolds and receptors. Here we image inhibitory synapses containing fluorescently tagged postsynaptic scaffold Gephyrin,together with presynaptic vesicular GABA transporter (VGAT) or postsynaptic GABA(A) receptor γ2 subunit (GABA(A)Rγ2),over seconds to days in cultured rat hippocampal neurons,revealing modes of inhibitory synapse formation and remodeling. Entire synapses were mobile,translocating rapidly within a confined region and exhibiting greater nonstochastic motion over multihour periods. Presynaptic and postsynaptic components moved in unison,maintaining close apposition while translocating distances of several micrometers. An observed flux in the density of synaptic puncta partially resulted from the apparent merging and splitting of preexisting clusters. De novo formation of inhibitory synapses was observed,marked by the appearance of stably apposed Gephyrin and VGAT clusters at sites previously lacking either component. Coclustering of GABA(A)Rγ2 supports the identification of such new clusters as synapses. Nascent synapse formation occurred by gradual accumulation of components over several hours,with VGAT clustering preceding that of Gephyrin and GABA(A)Rγ2. Comparing VGAT labeling by active uptake of a luminal domain antibody with post hoc immunocytochemistry indicated that recycling vesicles from preexisting boutons significantly contribute to vesicle pools at the majority of new inhibitory synapses. Although new synapses formed primarily on dendrite shafts,some also formed on dendritic protrusions,without apparent interconversion. Altogether,the long-term imaging of GABAergic presynaptic and postsynaptic components reveals complex dynamics and perpetual remodeling with implications for mechanisms of assembly and synaptic integration. View Publication

Schizophrenia has been defined as a neurodevelopmental disease that causes changes in the process of thoughts,perceptions,and emotions,usually leading to a mental deterioration and affective blunting. Studies have shown altered cell respiration and oxidative stress response in schizophrenia; however,most of the knowledge has been acquired from postmortem brain analyses or from nonneural cells. Here we describe that neural cells,derived from induced pluripotent stem cells generated from skin fibroblasts of a schizophrenic patient,presented a twofold increase in extramitochondrial oxygen consumption as well as elevated levels of reactive oxygen species (ROS),when compared to controls. This difference in ROS levels was reverted by the mood stabilizer valproic acid. Our model shows evidence that metabolic changes occurring during neurogenesis are associated with schizophrenia,contributing to a better understanding of the development of the disease and highlighting potential targets for treatment and drug screening. View Publication

Differentiation of pluripotent and lineage restricted stem cells such as neural stem cells (NSCs) was studied on conducting substrates of various nature without perturbation of the genome with exogenous genetic material or chemical stimuli. Primary mouse adult neural stem cells (NSCs) and P19 pluripotent embryonal (P19 EC) carcinoma cells were used. Expression levels of neuronal markers β-III-tubulin and neurofilament were evaluated by immunochemistry and flow cytometry. It was shown that the ability of the substrate to induce differentiation directly correlated with its conductivity. Conducting substrates (conducting oxides or doped pi-conjugated organic polymers) with different morphology,structure,and conductivity mechanisms all promoted differentiation of NSC and P19 cells into neuronal lineage to a similar degree without use of additional factors such as poly-L-ornithine coating or retinoic acid,as verified by their morphology and upregulation of the neuronal markers but not astrocyte marker GFAP. However,substrates with low conductance below ca. 10(-4) S cm(-2) did not show this ability. Morphology of differentiating cells was visualized by atomic force microscopy. NSCs cells increased β-III-tubulin expression by 95% and P19 cells by over 30%. Our results suggest that the substrate conductivity is a key factor governing the cell fate. Differentiation of P19 cells into neuronal lineage on conducting substrates was attributed to downregualtion of Akt signaling pathway and increase in expression of dual oxidase 1 (DUOX 1). View Publication

BACKGROUND Neuronal stem cells (NSCs) are promising for neurointestinal disease therapy. Although NSCs have been isolated from intestinal musclularis,their presence in mucosa has not been well described. Mucosa-derived NSCs are accessible endoscopically and could be used autologously. Brain-derived Nestin-positive NSCs are important in endogenous repair and plasticity. The aim was to isolate and characterize mucosa-derived NSCs,determine their relationship to Nestin-expressing cells and to demonstrate their capacity to produce neuroglial networks in vitro and in vivo. METHODS Neurospheres were generated from periventricular brain,colonic muscularis (Musc),and mucosa-submucosa (MSM) of mice expressing green fluorescent protein (GFP) controlled by the Nestin promoter (Nestin-GFP). Neuronal stem cells were also grown as adherent colonies from intestinal mucosal organoids. Their differentiation potential was assessed using immunohistochemistry using glial and neuronal markers. Brain and gut-derived neurospheres were transplanted into explants of chick embryonic aneural hindgut to determine their fate. KEY RESULTS Musc- and MSM-derived neurospheres expressed Nestin and gave rise to cells of neuronal,glial,and mesenchymal lineage. Although Nestin expression in tissue was mostly limited to glia co-labelled with glial fibrillary acid protein (GFAP),neurosphere-derived neurons and glia both expressed Nestin in vitro,suggesting that Nestin+/GFAP+ glial cells may give rise to new neurons. Moreover,following transplantation into aneural colon,brain- and gut-derived NSCs were able to differentiate into neurons. CONCLUSIONS & INFERENCES Nestin-expressing intestinal NSCs cells give rise to neurospheres,differentiate into neuronal,glial,and mesenchymal lineages in vitro,generate neurons in vivo and can be isolated from mucosa. Further studies are needed for exploring their potential for treating neuropathies. View Publication