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SummaryThe human brain microenvironment undergoes dynamic changes during development,which have been incompletely characterized in in vitro models including neural organoids. Here,we used liquid chromatography-mass spectrometry to investigate proteome and secretome changes in human dorsal forebrain organoids derived from three hiPSC lines at days 20,35,and 50 of differentiation. Proteome and immunohistochemical analysis revealed reduced proliferation and increased differentiation of progenitor cells gradually over time. In contrast,secretome analysis showed distinct characteristics at each timepoint — notably,at day 35,the numbers of cell adhesion molecules,synaptic proteins,and proteases were increased. Taken together,we present a resource describing the dynamic features of a neural organoid proteome and secretome across different genetic backgrounds. We describe the unique niche composition of neural organoids during the period of neurogenesis and suggest that synaptic proteins may play a role in guiding neurogenesis. Graphical abstract Highlights•Proteomic analysis of DFOs on three time points shows neural differentiation•Protein secretion increases during peak neurogenesis at D35 and D50•Cell adhesion molecules,synapse proteins,and metalloproteases are mainly secreted at D35•Extracellular matrix proteins are predominantly secreted at D50 Natural sciences; Biological sciences; Neuroscience; Tissue Engineering View Publication

Advancing cardiac tissue engineering requires innovative fabrication techniques,including 3D bioprinting and tissue maturation,to enable the generation of new muscle for repairing or replacing damaged heart tissue. Recent advances in tissue engineering have highlighted the need for rapid,high-resolution bioprinting methods that preserve cell viability and maintain structural fidelity. Traditional collagen-based bioinks gel slowly,limiting their use in bioprinting. Here,we implement TRACE (tunable rapid assembly of collagenous elements),a macromolecular crowding-driven bioprinting technique that enables the immediate gelation of collagen bioinks infused with cells. This overcomes the need for extended incubation,allowing for direct bioprinting of engineered cardiac tissues with high fidelity. Unlike methods that rely on high-concentration acidic collagen or fibrin for gelation,TRACE achieves rapid bioink stabilization without altering the biochemical composition. This ensures greater versatility in bioink selection while maintaining functional tissue outcomes. Additionally,agarose slurry provides stable structural support,preventing tissue collapse while allowing nutrient diffusion. This approach better preserves complex tissue geometries during culture than gelatin-based support baths or polydimethylsiloxane (PDMS) molds. Our results demonstrate that TRACE enables the bioprinting of structurally stable cardiac tissues with high resolution. By supporting the fabrication of biomimetic tissues,TRACE represents a promising advancement in bioprinting cardiac models and other engineered tissues. View Publication

Copy number variations of the human CNTN6 gene,resulting from megabase-scale microdeletions or microduplications in the 3p26.3 region,are frequently implicated in neurodevelopmental disorders such as intellectual disability and developmental delay. However,duplication of the full-length human CNTN6 gene presents with variable penetrance,resulting in phenotypes that range from neurodevelopmental disorders to no visible pathologies,even within the same family. Previously,we obtained a set of induced pluripotent stem cell lines derived from a patient with a CNTN6 gene duplication and from two healthy donors. Our findings demonstrated that CNTN6 expression in neurons carrying the duplication was significantly reduced. Additionally,the expression from the CNTN6 duplicated allele was markedly lower compared to the wild-type allele. Here,we first introduce a system for correcting megabase-scale duplications in induced pluripotent stem cells and secondly analyze the impact of this correction on CNTN6 gene expression. We showed that the deletion of one copy of the CNTN6 duplication did not affect the expression levels of the remaining allele in the neuronal cells. View Publication

Naive human embryonic stem cells (hESCs) that resemble the pre-implantation epiblasts are fueled by a combination of aerobic glycolysis and oxidative phosphorylation,but their mitochondrial regulators are poorly understood. Here we report that,proline dehydrogenase (PRODH),a mitochondria-localized proline metabolism enzyme,is dramatically upregulated in naive hESCs compared to their primed counterparts. The upregulation of PRODH is induced by a reduction in c-Myc expression that is dependent on PD0325901,a MEK inhibitor routinely present in naive hESC culture media. PRODH knockdown in naive hESCs significantly promoted mitochondrial oxidative phosphorylation (mtOXPHOS) and reactive oxygen species (ROS) production that triggered autophagy,DNA damage,and apoptosis. Remarkably,MitoQ,a mitochondria-targeted antioxidant,effectively restored the pluripotency and proliferation of PRODH-knockdown naive hESCs,indicating that PRODH maintains naive pluripotency by preventing excessive ROS production. Concomitantly,PRODH knockdown significantly slowed down the proteolytic degradation of multiple key mitochondrial electron transport chain complex proteins. Thus,we revealed a crucial role of PRODH in limiting mtOXPHOS and ROS production,and thereby safeguarding naive pluripotency of hESCs. Synopsis Downregulation of PRODH promotes oxidative phosphorylation and ROS production,which in turn impair pluripotency and proliferation of naive but not primed hESCs,revealing a crucial role of PRODH in safeguarding human naive pluripotency. PRODH is expressed in naive hESCs at a higher level compared to their primed counterparts.MEK inhibitor present in naive culture media upregulates PRODH by suppressing MYC.PRODH depletion boosts mtOXPHOS and ROS production in naive hESCs.PRODH promotes proteolytic degradation of the ETC complex components. Downregulation of PRODH promotes oxidative phosphorylation and ROS production,which in turn impair pluripotency and proliferation of naive but not primed hESCs,revealing a crucial role of PRODH in safeguarding human naive pluripotency. View Publication

SummaryGenome-wide association studies (GWAS) of Alzheimer’s disease (AD) have identified a plethora of risk loci. However,the disease variants/genes and the underlying mechanisms remain largely unknown. For a strong AD-associated locus near Clusterin (CLU),we tied an AD protective allele to a role of neuronal CLU in promoting neuron excitability through lipid-mediated neuron-glia communication. We identified a putative causal SNP of CLU that impacts neuron-specific chromatin accessibility to transcription-factor(s),with the AD protective allele upregulating neuronal CLU and promoting neuron excitability. Transcriptomic analysis and functional studies in induced pluripotent stem cell (iPSC)-derived neurons co-cultured with mouse astrocytes show that neuronal CLU facilitates neuron-to-glia lipid transfer and astrocytic lipid droplet formation coupled with reactive oxygen species (ROS) accumulation. These changes cause astrocytes to uptake less glutamate thereby altering neuron excitability. Our study provides insights into how CLU confers resilience to AD through neuron-glia interactions. View Publication

BackgroundMicroglia play important roles in maintaining brain homeostasis and neurodegeneration. The discovery of genetic variants in genes predominately or exclusively expressed in myeloid cells,such as Apolipoprotein E (APOE) and triggering receptor expressed on myeloid cells 2 (TREM2),as the strongest risk factors for Alzheimer’s disease (AD) highlights the importance of microglial biology in the brain. The sequence,structure and function of several microglial proteins are poorly conserved across species,which has hampered the development of strategies aiming to modulate the expression of specific microglial genes. One way to target APOE and TREM2 is to modulate their expression using antisense oligonucleotides (ASOs).MethodsIn this study,we identified,produced,and tested novel,selective and potent ASOs for human APOE and TREM2. We used a combination of in vitro iPSC-microglia models,as well as microglial xenotransplanted mice to provide proof of activity in human microglial in vivo.ResultsWe proved their efficacy in human iPSC microglia in vitro,as well as their pharmacological activity in vivo in a xenografted microglia model. We demonstrate ASOs targeting human microglia can modify their transcriptional profile and their response to amyloid-? plaques in vivo in a model of AD.ConclusionsThis study is the first proof-of-concept that human microglial can be modulated using ASOs in a dose-dependent manner to manipulate microglia phenotypes and response to neurodegeneration in vivo.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13024-024-00725-9. View Publication

Fluorescence microscopy has undergone rapid advancements,offering unprecedented visualization of biological events and shedding light on the intricate mechanisms governing living organisms. However,the exploration of rapid biological dynamics still poses a significant challenge due to the limitations of current digital camera architectures and the inherent compromise between imaging speed and other capabilities. Here,we introduce sHAPR,a high-speed acquisition technique that leverages the operating principles of sCMOS cameras to capture fast cellular and subcellular processes. sHAPR harnesses custom fiber optics to convert microscopy images into one-dimensional recordings,enabling acquisition at the maximum camera readout rate,typically between 25 and 250 kHz. We have demonstrated the utility of sHAPR with a variety of phantom and dynamic systems,including high-throughput flow cytometry,cardiomyocyte contraction,and neuronal calcium waves,using a standard epi-fluorescence microscope. sHAPR is highly adaptable and can be integrated into existing microscopy systems without requiring extensive platform modifications. This method pushes the boundaries of current fluorescence imaging capabilities,opening up new avenues for investigating high-speed biological phenomena. The authors introduce a highspeed acquisition technique,sHAPR,for rapid exploration of biodynamics using fluorescence microscopy. The method leverages sCMOS cameras and custom fibre optics to convert microscopy images into 1D recordings,enabling acquisition at the maximum camera readout rate. View Publication

SummaryThe neurodevelopmental disorders Prader-Willi syndrome (PWS) and Schaaf-Yang syndrome (SYS) both arise from genomic alterations within human chromosome 15q11–q13. A deletion of the SNORD116 cluster,encoding small nucleolar RNAs,or frameshift mutations within MAGEL2 result in closely related phenotypes in individuals with PWS or SYS,respectively. By investigation of their subcellular localization,we observed that in contrast to a predominant cytoplasmic localization of wild-type (WT) MAGEL2,a truncated MAGEL2 mutant was evenly distributed between the cytoplasm and the nucleus. To elucidate regulatory pathways that may underlie both diseases,we identified protein interaction partners for WT or mutant MAGEL2,in particular the survival motor neuron protein (SMN),involved in spinal muscular atrophy,and the fragile-X-messenger ribonucleoprotein (FMRP),involved in autism spectrum disorders. The interactome of the non-coding RNA SNORD116 was also investigated by RNA-CoIP. We show that WT and truncated MAGEL2 were both involved in RNA metabolism,while regulation of transcription was mainly observed for WT MAGEL2. Hence,we investigated the influence of MAGEL2 mutations on the expression of genes from the PWS locus,including the SNORD116 cluster. Thereby,we provide evidence for MAGEL2 mutants decreasing the expression of SNORD116,SNORD115,and SNORD109A,as well as protein-coding genes MKRN3 and SNRPN,thus bridging the gap between PWS and SYS. Graphical abstract Mutations within MAGEL2 from chromosomal region 15q11–q13 cause Schaaf-Yang syndrome,which is phenotypically related to Prader-Willi syndrome,caused by deletion of the SNORD116 cluster within the same locus. We correlate mutations within MAGEL2 to spinal muscular atrophy and autism and also demonstrate its influence on the abundance of SNORD116. View Publication

Propionic acidemia (PA) is a metabolic disorder caused by a deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC) due to mutations in the PCCA or PCCB genes,which encode the two PCC subunits. PA may lead to several types of cardiomyopathy and has been linked to cardiac electrical abnormalities such as QT interval prolongation,life-threatening arrhythmias,and sudden cardiac death. To gain insights into the mechanisms underlying PA-induced proarrhythmia,we recorded action potentials (APs) and ion currents using whole-cell patch-clamp in ventricular-like induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) from a PA patient carrying two pathogenic mutations in the PCCA gene (p.Cys616_Val633del and p.Gly477Glufs*9) (PCCA cells) and from a healthy subject (healthy cells). In cells driven at 1 Hz,PCC deficiency increased the latency and prolonged the AP duration (APD) measured at 20% of repolarization,without modifying resting membrane potential or AP amplitude. Moreover,delayed afterdepolarizations appeared at the end of the repolarization phase in unstimulated and paced PCCA cells. PCC deficiency significantly reduced peak sodium current (INa) but increased the late INa (INaL) component. In addition,L-type Ca2+ current (ICaL) density was reduced,while the inward and outward density of the Na+/Ca2+ exchanger current (INCX) was increased in PCCA cells compared to healthy ones. In conclusion,our results demonstrate that at the cellular level,PCC deficiency can modify the ion currents controlling cardiac excitability,APD,and intracellular Ca2+ handling,increasing the risk of arrhythmias independently of the progressive late-onset cardiomyopathy induced by PA disease. View Publication

ABSTRACTRAD50?interacting protein1 (RINT1) deficiency has been implicated in recurrent acute liver failure (RALF) triggered by fever or infections. RINT1,together with neuroblastoma amplified sequence and Zeste White 10 (forming the NRZ complex),localizes at the interface between the endoplasmic reticulum and Golgi apparatus,where it plays a key role in vesicular trafficking. However,the mechanisms by which RINT1 deficiency leads to RALF remain unclear. This study aimed to describe a woman with RALF harboring a homozygous missense mutation in RINT1. Induced pluripotent stem cells (iPSCs) were generated from the patient's mononuclear cells and differentiated into hepatocyte?like cells (HLCs). Upon exposure to high temperature (40°C),RINT1?deficient HLCs exhibited cellular damage characteristic of RALF. Furthermore,these cells also demonstrated heightened sensitivity to cytokines and viral mimetics while showing comparatively lower responsiveness to bacterial infection?related stimuli. Transcriptome sequencing revealed dysregulated gene expression associated with the extracellular matrix (ECM). Additionally,glycosaminoglycan disaccharide analysis revealed abnormal levels of chondroitin sulfate,heparan sulfate,and hyaluronan in RINT1?deficient HLCs. In conclusion,HLCs derived from RINT1?deficient iPSCs serve as a valuable model for investigating RINT1?related liver pathogenesis. The results suggest that cytokine responses,particularly those triggered by viral infections,play a central role in the development of RALF. Furthermore,ECM alterations provided novel insights into the potential role of RINT1 defects in RALF. RAD50?interacting protein1 (RINT1) deficiency causes recurrent acute liver failure (RALF) during fever or infections. To investigate its underlying mechanism,induced pluripotent stem cells were generated from a patient with RINT1 deficiency and differentiated into hepatocyte?like cells (HLCs). RINT1?deficient HLCs exhibited damage resembling RALF when exposed to high temperatures and were more susceptible to cytokines and viral mimetics than to bacterial infection?related factors. Furthermore,RNA?seq and disaccharide analyses revealed dysregulation of extracellular matrix?related genes and abnormalities in extracellular matrix levels. View Publication

Remarkable advances in protocol development have been achieved to manufacture insulin-secreting islets from human pluripotent stem cells (hPSCs). Distinct from current approaches,we devised a tunable strategy to generate islet spheroids enriched for major islet cell types by incorporating PDX1+ cell budding morphogenesis into staged differentiation. In this process that appears to mimic normal islet morphogenesis,the differentiating islet spheroids organize with endocrine cells that are intermingled or arranged in a core-mantle architecture,accompanied with functional heterogeneity. Through in vitro modelling of human pancreas development,we illustrate the importance of PDX1 and the requirement for EphB3/4 signaling in eliciting cell budding morphogenesis. Using this new approach,we model Mitchell-Riley syndrome with RFX6 knockout hPSCs illustrating unexpected morphogenesis defects in the differentiation towards islet cells. The tunable differentiation system and stem cell-derived islet models described in this work may facilitate addressing fundamental questions in islet biology and probing human pancreas diseases. The ability to differentiate human pluripotent stem cells (hPSCs) into insulin producing cells holds potential for diabetes treatments,but many of these approaches lack the complexity needed for in vitro disease modeling. Here they develop an hPSC-derived islet spheroid system,offering an experimental model to study pancreatic budding and islet morphogenesis with human cells. View Publication

Creatine transporter deficiency (CTD) is an X-linked disease caused by mutations in the Slc6a8 gene. The impaired creatine uptake in the brain leads to developmental delays with intellectual disability. We hypothesized that deficient creatine uptake in CTD cerebral cells impact methylation balance leading to alterations of genes and proteins expression by epigenetic mechanism. In this study,we determined the status of nucleic acid methylation in both Slc6a8 knockout mouse model and brain organoids derived from CTD patients’ cells. We also investigated the effect of dodecyl creatine ester (DCE),a promising prodrug that increases brain creatine content in the mouse model of CTD. The level of nucleic acid methylation was significantly reduced compared to healthy controls in both in vivo and in vitro CTD models. This hypo-methylation tended to be regulated by DCE treatment in vivo. These results suggest that increased brain creatine after DCE treatment restores normal levels of DNA methylation,unveiling the potential of using DNA methylation as a marker to monitor the drug efficacy. View Publication