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SummaryRibosomopathies arise from the disruptions in ribosome biogenesis within the nucleolus,which is organized via liquid-liquid phase separation (LLPS). The roles of LLPS in ribosomopathies remain poorly understood. Here,we generated human induced pluripotent stem cell (hiPSC) models of ribosomopathy caused by mutations in small nucleolar RNA (snoRNA) gene SNORD118. Mutant hiPSC-derived neural progenitor cells (NPCs) or neural crest cells (NCCs) exhibited ribosomopathy hallmark cellular defects resulting in reduced organoid growth,recapitulating developmental delay in patients. SNORD118 mutations in NPCs disrupted nucleolar morphology and LLPS properties coupled with impaired ribosome biogenesis and a translational downregulation of fibrillarin (FBL),the key LLPS effector acting via the intrinsically disordered region (IDR) motif. IDR-depleted FBL failed to rescue NPC defects,whereas a chimeric FBL with swapped IDR motif from an unrelated protein mitigated ribosomopathy and organoid growth defects. Thus,SNORD118 human iPSC models revealed aberrant phase separation and nucleolar functions as potential pathogenic mechanisms in ribosomopathies. Graphical abstract Highlights•SNORD118 mutant hiPSC-derived cells and organoids recapitulate the ribosomopathy defects•Mutations impair ribosome biogenesis and translation of phase separation effector FBL•Phase separation and nucleolar organization are defective in SNORD118 mutant cells•Impaired phase separation causes ribosomopathy and growth defects in hiPSC models Natural sciences; Biological sciences; Cell biology; Stem cell research View Publication

Haloperidol is a typical antipsychotic used to treat schizophrenia and induces dopamine D2 receptor antagonism. Long-term use of haloperidol can reduce brain size in animals and humans; however,the underlying mechanism of this effect remains unclear. Notch1 signaling regulates the development and function of the nervous system by balancing stem cell proliferation and differentiation. Therefore,we investigated the effects of long-term exposure to haloperidol on human-derived brain organoids,which served as sophisticated in vitro models of human brain development. Long-term exposure to haloperidol reduced the size of brain organoids and decreased the ventricular zone and Notch1 signaling. When propionate,which protects against haloperidol-induced toxicity,was combined with haloperidol,it rescued both the overall size of brain organoids and Notch1 expression levels. Additionally,treatment with valproic acid,a Notch1 activator,partially restored the size of brain organoids and the thickness of the ventricular layer. Taken together,these data suggest that long-term exposure to haloperidol impairs neurodevelopment via Notch1 signaling in brain organoids. These findings contribute to our understanding of antipsychotic drug safety and provide information for new neurodevelopmental toxicity assessments.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-08855-w. View Publication

Alternative splicing (AS) is a crucial mechanism contributing to proteomic diversity,which is highly regulated in tissue- and development-specific patterns. Retinal tissue exhibits one of the highest levels of AS. In particular,photoreceptors have a distinctive AS pattern involving the inclusion of microexons not found in other cell types. PROM1 whose encoded protein Prominin-1 is located in photoreceptor outer segments (OSs),undergoes exon 4 inclusion from the 12th post-conception week of human development through adulthood. Exon 4 skipping in PROM1 is associated with late-onset mild maculopathy,however its role in photoreceptor maturation and function is unknown. In this study retinal organoids,a valuable model system,were employed in combination with phosphorodiamidate morpholino oligos (PMOs) to assess the role of exon 4 AS in the development of human retina. Retinal organoids were treated with the PMOs for four weeks after which RT-PCR,western blotting and immunofluorescence analysis were performed to assess exon 4 exclusion and its impact on photoreceptors. The transcriptome of treated ROs was studied by bulk RNA-Seq. Our data demonstrate that 55% skipping of PROM1 exon 4 resulted in decreased Prominin-1 expression by 40%,abnormal accumulation of cones in the basal side of the retinal organoids as well as detectable cone photoreceptor cilium defects. Transcriptomic and western blot analyses revealed decreased expression of cone,inner segment and connecting cilium basal body markers,increased expression of genes associated with stress response and the ubiquitin-proteasome system,and downregulation of autophagy. Importantly,the use of retinal organoids provides a valuable platform to study AS and unravel disease mechanisms in a more physiologically relevant context,opening avenues for further research and potential therapeutic interventions. Together our data indicate that cones may be more sensitive to PROM1 exon 4 skipping and/or reduced Prominin-1 expression,corroborating the pathogenesis of late-onset mild maculopathy. View Publication

Several differentiation protocols have enabled the generation of intermediate mesoderm (IM)-derived cells from human pluripotent stem cells (hPSC). However,the substantial variability between existing protocols for generating IM cells compromises their efficiency,reproducibility,and overall success,potentially hindering the utility of urogenital system organoids. Here,we examined the role of high levels of Nodal signaling and BMP activity,as well as WNT signaling in the specification of IM cells derived from a UCSD167i-99-1 human induced pluripotent stem cells (hiPSC) line. We demonstrate that precise modulation of WNT and BMP signaling significantly enhances IM differentiation efficiency. Treatment of hPSC with 3 ?M CHIR99021 induced TBXT+/MIXL1+ mesoderm progenitor (MP) cells after 48 h of differentiation. Further treatment with a combination of 3 ?M CHIR99021 and 4 ng/mL BMP4 resulted in the generation of OSR1+/GATA3+/PAX2+ IM cells within a subsequent 48 h period. Molecular characterization of differentiated cells was confirmed through immunofluorescence staining and RT-qPCR. Hence,this study establishes a consistent and reproducible protocol for differentiating hiPSC into IM cells that faithfully recapitulates the molecular signatures of IM development. This protocol holds promise for improving the success of protocols designed to generate urogenital system organoids in vitro,with potential applications in regenerative medicine,drug discovery,and disease modeling. View Publication

Sustained smouldering,or low-grade activation,of myeloid cells is a common hallmark of several chronic neurological diseases,including multiple sclerosis1. Distinct metabolic and mitochondrial features guide the activation and the diverse functional states of myeloid cells2. However,how these metabolic features act to perpetuate inflammation of the central nervous system is unclear. Here,using a multiomics approach,we identify a molecular signature that sustains the activation of microglia through mitochondrial complex I activity driving reverse electron transport and the production of reactive oxygen species. Mechanistically,blocking complex I in pro-inflammatory microglia protects the central nervous system against neurotoxic damage and improves functional outcomes in an animal disease model in vivo. Complex I activity in microglia is a potential therapeutic target to foster neuroprotection in chronic inflammatory disorders of the central nervous system3. Blocking mitochondrial complex I in pro-inflammatory microglia protects the central nervous system against neurotoxic damage and improves functional outcomes in vivo in an animal disease model. View Publication

Huntington disease (HD) is a neurodegenerative disease caused by the abnormal expansion of a polyglutamine tract resulting from a mutation in the HTT gene. Oxidative stress has been identified as a significant contributing factor to the development of HD and other neurodegenerative diseases,and targeting anti-oxidative stress has emerged as a potential therapeutic approach. CHCHD2 is a mitochondria-related protein involved in regulating cell migration,anti-oxidative stress,and anti-apoptosis. Although CHCHD2 is highly expressed in HD cells,its specific role in the pathogenesis of HD remains uncertain. We postulate that the up-regulation of CHCHD2 in HD models represents a compensatory protective response against mitochondrial dysfunction and oxidative stress associated with HD. To investigate this hypothesis,we employed HD mouse striatal cells and human induced pluripotent stem cells (hiPSCs) as models to examine the effects of CHCHD2 overexpression (CHCHD2-OE) or knockdown (CHCHD2-KD) on the HD phenotype. Our findings demonstrate that CHCHD2 is crucial for maintaining cell survival in both HD mouse striatal cells and hiPSCs-derived neurons. Our study demonstrates that CHCHD2 up-regulation in HD serves as a compensatory protective response against oxidative stress,suggesting a potential anti-oxidative strategy for the treatment of HD. View Publication