技术资料

Alpha-synuclein (aSyn) post-translational modifications (PTM),especially phosphorylation at serine 129 and C-terminal truncations,are highly enriched in Lewy bodies (LB),Lewy neurites,and other pathological aggregates in Parkinson’s disease and synucleinopathies. However,the precise role of these PTM in pathology formation,neurodegeneration,and pathology spreading remains unclear. Here,we systematically investigated the role of post-fibrillization C-terminal aSyn truncations in regulating uptake,processing,seeding,and LB-like inclusion formation using a neuronal seeding model that recapitulates LB formation and neurodegeneration. We show that C-terminal cleavage of aSyn fibrils occurs rapidly post exogenous fibril internalization and during intracellular LB-like inclusion formation. Blocking cleavage of internalized fibrils does not affect seeding,but inhibiting enzymes such as calpains 1 and 2 alters LB-like inclusion formation. We show that C-terminal truncations,along with other PTMs,regulate fibril interactome remodeling,shortening,lateral association,and packing. These findings reveal distinct roles of C-terminal truncations at different aggregation stages on the pathway to LB formation,highlighting the need for consideration of stage‑specific strategies to target aSyn proteolytic cleavages. View Publication

Variants of phospholipase C gamma 2 (PLCG2),a key microglial immune signaling protein,are genetically linked to Alzheimer's disease (AD) risk. Understanding how PLCG2 variants alter microglial function is critical for identifying mechanisms that drive neurodegeneration or resiliency in AD. Induced pluripotent stem cell (iPSC) –derived microglia carrying the protective PLCG2 P522R or risk‐conferring PLCG2 M28L variants,or loss of PLCG2,were generated to ascertain the impact on microglial transcriptome and function. Protective PLCG2 P522R microglia showed significant transcriptomic similarity to isogenic controls. In contrast,risk‐conferring PLCG2 M28L microglia shared similarities with PLCG2 KO microglia,with functionally reduced TREM2 expression,blunted inflammatory responses,and increased proliferation and cell death. Uniquely,PLCG2 P522R microglia showed elevated cytokine secretion after lipopolysaccharide (LPS) stimulation and were protected from apoptosis. These findings demonstrate that PLCG2 variants drive distinct microglia transcriptomes that influence microglial functional responses that could contribute to AD risk and protection. Targeting PLCG2‐mediated signaling may represent a powerful therapeutic strategy to modulate neuroinflammation. The impact of Alzheimer's disease protective‐ and risk‐associated variants of phospholipase C gamma 2 (PLCG2) on the transcriptome and function of induced pluripotent stem cell (iPSC) –derived microglia was investigated. PLCG2 risk variant microglia exhibited a basal transcriptional profile similar to PLCG2‐deficient microglia but significantly different from isotype control and the transcriptionally similar PLCG2 protective variant microglia. PLCG2 risk variant and PLCG2‐deficient microglia show decreased levels of triggering receptor expressed on myeloid cells 2 (TREM2). The differential transcriptional pathways of protective and risk‐associated PLCG2 variant microglia functionally affect proliferation,apoptosis,and immune response. Protective PLCG2 microglia show resilience to apoptosis and increased cytokine/chemokine secretion upon exposure to lipopolysaccharide (LPS). View Publication

Understanding diseases as the result of continuous transitions from a healthy system is more realistic than understanding them as discrete states. Here,we designed the spectrum formation approach (SFA),a machine learning-based method that extracts key features contributing to disease state continuity. We applied the SFA to transcriptomic data from patients with progressive liver disease and neurodegenerative movement disorders to examine its effectiveness in identifying biologically relevant gene sets. The SFA identified transcription factors that potentially regulate liver inflammation and voluntary movement. In neurodegenerative disorders,the SFA also identified genes regulated by ETS-1,with unclear effects on movement. In functional assessment using human iPSC-derived neurons,ETS-1 overexpression disrupted dopamine receptor balance,reduced GABA-producing enzyme levels,and promoted cell death. These findings suggest that the SFA enables the discovery of regulatory factors capable of modifying disease states and provides a framework for the continuity-based interpretation of biological systems. Subject terms: Diseases,Pathogenesis,Signs and symptoms View Publication

Brain organoids derived from human pluripotent stem cells (hPSCs) hold immense potential for modeling neurodevelopmental processes and disorders. However,their experimental variability and undefined organoid selection criteria for analysis hinder reproducibility. As part of the Bavarian ForInter consortium,we generated 72 brain organoids from distinct hPSC lines. We conducted a comprehensive analysis of their morphological and cellular characteristics at an early stage of their development. In our assessment,the Feret diameter emerged as a reliable,single parameter that characterizes brain organoid quality. Transcriptomic analysis of our organoid identified the abundance of unintended mesodermal differentiation as a major confounder of unguided brain organoid differentiation,correlating with Feret diameter. High-quality organoids consistently displayed a lower presence of mesenchymal cells. These findings provide a framework for enhancing brain organoid standardization and reproducibility,underscoring the need for morphological quality controls and considering the influence of mesenchymal cells on organoid-based modeling. Subject terms: Mesenchymal stem cells,Induced pluripotent stem cells,Stem-cell differentiation View Publication

Differentiation of embryonic stem cells and induced pluripotent stem cells (iPSCs) into endoderm derivatives,including thyroid,thymus,lungs,liver,and pancreas,has broad implications for disease modeling and therapy. We utilize and expand a model development approach previously outlined by the authors to construct a model for the directed differentiation of iPSCs into definitive endoderm (DE). Assuming discrete intermediate stages in the differentiation process with a homogeneous population in each stage,three lineage models with two,three,and four populations and three growth models are constructed. Additionally,three models for error distribution are defined,resulting in a total of 27 models. Experimental data obtained in vitro are used for model calibration,model selection,and final validation. Model selection suggests that no transitory state during differentiation expresses the DE biomarkers CD117 and CD184,a finding corroborated by existing literature. Additionally,space-limited growth models,such as logistic and Gompertz growth,outperform exponential growth. Validation of the inferred model with leave-out data results in prediction errors of 26.4%. Using the inferred model,it is predicted that the optimal differentiation period is between 1.9 and 2.4 days,plating populations closer to 300 000 cells per well result in the highest yield efficiency,and that iPSC differentiation outpaces the DE proliferation as the main driver of the population dynamics. We also demonstrate that the model can predict the effect of growth modulators on cell population dynamics. Our model serves as a valuable tool for optimizing differentiation protocols,providing insights into developmental biology. View Publication

INTRODUCTIONPolygenic risk score (PRS) identifies individuals at high genetic risk for Alzheimer's disease (AD),but its utility in predicting cognitive trajectories and AD pathologies remains unclear. We optimized PRS (optPRS) for AD,investigated its association with cognitive trajectories and AD phenotypes of cerebral organoids.METHODSUsing genome‐wide association study (GWAS) summary statistics from a European population,we developed optPRS to predict AD in Korean individuals (n = 1634). We analyzed the association between optPRS and cognitive trajectories (n = 771). We generated induced pluripotent stem cell–derived cerebral organoids from patients with high (n = 3) and low (n = 4) optPRS to evaluate amyloid beta (Aβ) and phosphorylated tau (p‐tau) levels.RESULTSOptPRS predicted AD dementia and Aβ positivity,independent of apolipoprotein E (APOE). Higher optPRSs correlated with rapid cognitive decline. Cerebral organoids from the high optPRS group exhibited increased Aβ insolubility and p‐tau levels.CONCLUSIONOptPRS predicted cognitive decline and AD phenotypes of cerebral organoids,supporting its use in risk assessments and drug‐screening platform. View Publication

MYCN amplification without concurrent RB1 mutations characterizes a rare yet highly aggressive subtype of retinoblastoma; however,its precise developmental origins and therapeutic vulnerabilities remain incompletely understood. Here,we modeled this subtype by lentiviral-mediated MYCN overexpression in human pluripotent stem cell-derived retinal organoids,revealing a discrete developmental window (days 70–120) during which retinal progenitors showed heightened susceptibility to transformation. Tumors arising in this period exhibited robust proliferation,expressed SOX2,and lacked CRX,consistent with origin from primitive retinal progenitors. MYCN-overexpressing organoids generated stable cell lines that reproducibly gave rise to MYCN-driven tumors when xenografted into immunodeficient mice. Transcriptomic profiling demonstrated that MYCN-overexpressing organoids closely recapitulated molecular features of patient-derived MYCN-amplified retinoblastomas,particularly through activation of MYC/E2F and mTORC1 signaling pathways. Pharmacological screening further identified distinct therapeutic vulnerabilities,demonstrating distinct subtype-specific sensitivity of MYCN-driven cells to transcriptional inhibitors (THZ1,Flavopiridol) and the cell-cycle inhibitor Volasertib,indicative of a unique oncogene-addicted state compared to RB1-deficient retinoblastoma cells. Collectively,our study elucidates the developmental and molecular mechanisms underpinning MYCN-driven retinoblastoma,establishes a robust and clinically relevant human retinal organoid platform,and highlights targeted transcriptional inhibition as a promising therapeutic approach for this aggressive pediatric cancer subtype. View Publication

Embryonic stem cells (ESC) are pluripotent,with the potential to differentiate into multiple cell types,making them a valuable tool for regenerative medicine and disease therapy. However,common culture methods face challenges,including strict operating procedures and high costs. Currently,Leukemia inhibitory factor (LIF),an indispensable bioactive protein for ESC culture,is typically applied to maintain self-renewal and pluripotency,but its instability and high cost limit its effectiveness in stable culture conditions. Hence,we have developed an innovative strategy using a soluble nanomaterial,metal-organic polyhedra (MOPs),to effectively maintain the self-renewal and pluripotency of ESC. The selected amino-modified vanadium-based MOP not only exhibits excellent biocompatibility and high stability but also possesses similar or even superior biological functions compared to commercial LIF. Due to the precise structure of MOPs,the active site responsible for maintaining ESC pluripotency has been identified and regulated at the molecular level. The new ESC culture method significantly reduces costs,simplifies preparation,and enhances the practicality of biopharmaceutical preparation and storage. This represents the first case of using MOPs to maintain self-renewal of ECS,opening an avenue for introducing advanced materials into the development of innovative ESC culture methods. Subject terms: Biomaterials - cells,Chemical biology View Publication