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ObjectivesMutations in Tissue Inhibitor of Metalloproteinases 3 (TIMP3) cause Sorsby's Fundus Dystrophy (SFD),a dominantly inherited,rare form of macular degeneration that results in vision loss. TIMP3 is synthesized primarily by retinal pigment epithelial (RPE) cells,which constitute the outer blood-retinal barrier. One major function of RPE is the synthesis and transport of vital nutrients,such as glucose,to the retina. Recently,metabolic dysfunction in RPE cells has emerged as an important contributing factor in retinal degenerations. We set out to determine if RPE metabolic dysfunction was contributing to SFD pathogenesis.MethodsQuantitative proteomics was conducted on RPE of mice expressing the S179C variant of TIMP3,known to be causative of SFD in humans. Proteins found to be differentially expressed (P < 0.05) were analyzed using statistical overrepresentation analysis to determine enriched pathways,processes,and protein classes using g:profiler and PANTHER Gene Ontology. We examined the effects of mutant TIMP3 on RPE metabolism using human ARPE-19 cells expressing mutant S179C TIMP3 and patient-derived induced pluripotent stem cell-derived RPE (iRPE) carrying the S204C TIMP3 mutation. RPE metabolism was directly probed using isotopic tracing coupled with GC/MS analysis. Steady state [U–13C6] glucose isotopic tracing was preliminarily conducted on S179C ARPE-19 followed by [U–13C6] glucose and [U–13C5] glutamine isotopic tracing in SFD iRPE cells.ResultsQuantitative proteomics and enrichment analysis conducted on RPE of mice expressing mutant S179C TIMP3 identified differentially expressed proteins that were enriched for metabolism-related pathways and processes. Notably these results highlighted dysregulated glycolysis and glucose metabolism. Stable isotope tracing experiments with [U–13C6] glucose demonstrated enhanced glucose utilization and glycolytic activity in S179C TIMP3 APRE-19 cells. Similarly,[U–13C6] glucose tracing in SFD iRPE revealed increased glucose contribution to glycolysis and the TCA cycle. Additionally,[U–13C5] glutamine tracing found evidence of altered malic enzyme activity.ConclusionsThis study provides important information on the dysregulation of RPE glucose metabolism in SFD and implicates a potential commonality with other retinal degenerative diseases,emphasizing RPE cellular metabolism as a therapeutic target. Highlights•SFD mice display alterations in proteins associated with metabolism.•SFD RPE cells have increased glycolytic activity and glucose contribution to the TCA cycle.•Glutamine contribution to energy metabolism is unaltered in SFD RPE cells however there is reduced malic enzyme activity.•SFD RPE cells display metabolic dysfunction potentially implicating metabolism as a viable therapeutic target. View Publication

The reconstruction of damaged neural circuits is critical for neurological repair after brain injury. Classical brain-computer interfaces (BCIs) allow direct communication between the brain and external controllers to compensate for lost functions. Importantly,there is increasing potential for generalized BCIs to input information into the brains to restore damage,but their effectiveness is limited when a large injured cavity is caused. Notably,it might be overcome by transplantation of brain organoids into the damaged region. Here,we construct innovative BCIs mediated by implantable organoids,coined as organoid-brain-computer interfaces (OBCIs). We assess the prolonged safety and feasibility of the OBCIs,and explore neuroregulatory strategies. OBCI stimulation promotes progressive differentiation of grafts and enhances structural-functional connections within organoids and the host brain,promising to repair the damaged brain via regenerating and regulating,potentially directing neurons to preselected targets and recovering functional neural networks in the future. Damaged neural circuits could be improved by generalized BCIs via inputting information into the brains,which is restricted when a large injured cavity caused. Here,the authors construct BCIs mediated by organoid grafts to repair the damaged brain View Publication

Mutations in GBA1 encoding the lysosomal enzyme ?-glucocerebrosidase (GCase) are among the most prevalent genetic susceptibility factors for Parkinson’s disease (PD),with 10–30% of carriers developing the disease. To identify genetic modifiers contributing to the incomplete penetrance,we examined the effect of 1634 human transcription factors (TFs) on GCase activity in lysates of an engineered human glioblastoma line homozygous for the pathogenic GBA1 L444P variant. Using an arrayed CRISPR activation library,we uncovered 11 TFs as regulators of GCase activity. Among these,activation of MITF and TFEC increased lysosomal GCase activity in live cells,while activation of ONECUT2 and USF2 decreased it. While MITF,TFEC,and USF2 affected GBA1 transcription,ONECUT2 might control GCase trafficking. The effects of MITF,TFEC,and USF2 on lysosomal GCase activity were reproducible in iPSC-derived neurons from PD patients. Our study provides a systematic approach to identifying modulators of GCase activity and deepens our understanding of the mechanisms regulating GCase. View Publication

The fatal motor neuron (MN) disease amyotrophic lateral sclerosis (ALS) is characterized by progressive degeneration of the phrenic MNs (phMNs) controlling the activity of the diaphragm,leading to death by respiratory failure. Human experimental models to study phMNs are lacking,hindering the understanding of the mechanisms of phMN degeneration in ALS. Here,we describe a protocol to derive phrenic-like MNs from human induced pluripotent stem cells (hiPSC-phMNs) within 30 days. During spinal cord development,phMNs emerge from specific MN progenitors located in the dorsalmost MN progenitor (pMN) domain at cervical levels,under the control of a ventral-to-dorsal gradient of Sonic hedgehog (SHH) signaling and a rostro-caudal gradient of retinoic acid (RA). The method presented here uses optimized concentrations of RA and the SHH agonist purmorphamine,followed by fluorescence-activated cell sorting (FACS) of the resulting MN progenitor cells (MNPCs) based on a cell-surface protein (IGDCC3) enriched in hiPSC-phMNs. The resulting cultures are highly enriched in MNs expressing typical phMN markers. This protocol enables the generation of hiPSC-phMNs and is highly reproducible using several hiPSC lines,offering a disease-relevant system to study mechanisms of respiratory MN dysfunction. While the protocol has been validated in the context of ALS research,it can be adopted to study human phrenic MNs in other research fields where these neurons are of interest. View Publication

Genetic and experimental evidence suggests that Alzheimer’s disease (AD) risk alleles and genes may influence disease susceptibility by altering the transcriptional and cellular responses of macrophages,including microglia,to damage of lipid-rich tissues like the brain. Recently,sc/nRNA sequencing studies identified similar transcriptional activation states in subpopulations of macrophages in aging and degenerating brains and in other diseased lipid-rich tissues. We collectively refer to these subpopulations of microglia and peripheral macrophages as DLAMs. Using macrophage sc/nRNA-seq data from healthy and diseased human and mouse lipid-rich tissues,we reconstructed gene regulatory networks and identified 11 strong candidate transcriptional regulators of the DLAM response across species. Loss or reduction of two of these transcription factors,BHLHE40/41,in iPSC-derived microglia and human THP-1 macrophages as well as loss of Bhlhe40/41 in mouse microglia,resulted in increased expression of DLAM genes involved in cholesterol clearance and lysosomal processing,increased cholesterol efflux and storage,and increased lysosomal mass and degradative capacity. These findings provide targets for therapeutic modulation of macrophage/microglial function in AD and other disorders affecting lipid-rich tissues. Factors regulating lipid and lysosomal clearance in microglia and peripheral macrophage are not known. Here,authors nominate and validate transcription factors BHLHE40 and BHLHE41 as regulators of these processes in health and disease. View Publication

The ability to derive retinal ganglion cells (RGCs) from human pluripotent stem cells (hPSCs) has led to numerous advances in the field of retinal research,with great potential for the use of hPSC-derived RGCs for studies of human retinal development,in vitro disease modeling,drug discovery,as well as their potential use for cell replacement therapeutics. Of all these possibilities,the use of hPSC-derived RGCs as a human-relevant platform for in vitro disease modeling has received the greatest attention,due to the translational relevance as well as the immediacy with which results may be obtained compared to more complex applications like cell replacement. While several studies to date have focused upon the use of hPSC-derived RGCs with genetic variants associated with glaucoma or other optic neuropathies,many of these have largely described cellular phenotypes with only limited advancement into exploring dysfunctional cellular pathways as a consequence of the disease-associated gene variants. Thus,to further advance this field of research,in the current study we leveraged an isogenic hPSC model with a glaucoma-associated mutation in the Optineurin (OPTN) protein,which plays a prominent role in autophagy. We identified an impairment of autophagic-lysosomal degradation and decreased mTORC1 signaling via activation of the stress sensor AMPK,along with subsequent neurodegeneration in OPTN(E50K) RGCs differentiated from hPSCs,and have further validated some of these findings in a mouse model of ocular hypertension. Pharmacological inhibition of mTORC1 in hPSC-derived RGCs recapitulated disease-related neurodegenerative phenotypes in otherwise healthy RGCs,while the mTOR-independent induction of autophagy reduced protein accumulation and restored neurite outgrowth in diseased OPTN(E50K) RGCs. Taken together,these results highlighted that autophagy disruption resulted in increased autophagic demand which was associated with downregulated signaling through mTORC1,contributing to the degeneration of RGCs.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40478-024-01872-2. View Publication

Central nervous system (CNS) cancers are responsible for high rates of morbidity and mortality worldwide. Malignant CNS tumors such as adult Glioblastoma (GBM) and pediatric embryonal CNS tumors such as medulloblastoma (MED) and atypical teratoid rhabdoid tumors (ATRT) present relevant therapeutic challenges due to the lack of response to classic treatment regimens with radio and chemotherapy. Recent findings on the Zika virus’ (ZIKV) ability to infect and kill CNS neoplastic cells draw attention to the virus’ oncolytic potential. Studies demonstrating the safety of using ZIKV for treating malignant CNS tumors,enabling the translation of this approach to clinical trials,are scarce in the literature. Here we developed a co-culture model of mature human cerebral organoids assembled with GBM,MED or ATRT tumor cells and used these assembloids to test ZIKV oncolytic effect,replication potential and preferential targeting between normal and cancer cells. Our hybrid co-culture models allowed the tracking of tumor cell growth and invasion in cerebral organoids. ZIKV replication and ensuing accumulation in the culture medium was higher in organoids co-cultured with tumor cells than in isolated control organoids without tumor cells. ZIKV infection led to a significant reduction in tumor cell proportion in organoids with GBM and MED cells,but not with ATRT. Tumoroids (3D cultures of tumor cells alone) were efficiently infected by ZIKV. Interestingly,ZIKV rapidly replicated in GBM,MED,and ATRT tumoroids reaching significantly higher viral RNA accumulation levels than co-cultures. Moreover,ZIKV infection reduced viable cells number in MED and ATRT tumoroids but not in GBM tumoroids. Altogether,our findings indicate that ZIKV has greater replication rates in aggressive CNS tumor cells than in normal human cells comprising cerebral organoids. However,such higher ZIKV replication in tumor cells does not necessarily parallels oncolytic effects,suggesting cellular intrinsic and extrinsic factors mediating tumor cell death by ZIKV. View Publication

Genome editing is poised to revolutionize treatment of genetic diseases,but poor understanding and control of DNA repair outcomes hinders its therapeutic potential. DNA repair is especially understudied in nondividing cells like neurons,which must withstand decades of DNA damage without replicating. This lack of knowledge limits the efficiency and precision of genome editing in clinically relevant cells. To address this,we used induced pluripotent stem cells (iPSCs) and iPSC-derived neurons to examine how postmitotic human neurons repair Cas9-induced DNA damage. We discovered that neurons can take weeks to fully resolve this damage,compared to just days in isogenic iPSCs. Furthermore,Cas9-treated neurons upregulated unexpected DNA repair genes,including factors canonically associated with replication. Manipulating this response with chemical or genetic perturbations allowed us to direct neuronal repair toward desired editing outcomes. By studying DNA repair in postmitotic human cells,we uncovered unforeseen challenges and opportunities for precise therapeutic editing. View Publication

Heterozygous de novo mutations in the Activity-Dependent Neuroprotective Homeobox (ADNP) gene underlie Helsmoortel-Van der Aa syndrome (HVDAS). Most of these mutations are situated in the last exon and we previously demonstrated escape from nonsense-mediated decay by detecting mutant ADNP mRNA in patient blood. In this study,wild-type and ADNP mutants are investigated at the protein level and therefore optimal detection of the protein is required. Detection of ADNP by means of western blotting has been ambiguous with reported antibodies resulting in non-specific bands without unique ADNP signal. Validation of an N-terminal ADNP antibody (Aviva Systems) using a blocking peptide competition assay allowed to differentiate between specific and non-specific signals in different sample materials,resulting in a unique band signal around 150 kDa for ADNP,above its theoretical molecular weight of 124 kDa. Detection with different C-terminal antibodies confirmed the signals at an observed molecular weight of 150 kDa. Our antibody panel was subsequently tested by immunoblotting,comparing parental and homozygous CRISPR/Cas9 endonuclease-mediated Adnp knockout cell lines and showed disappearance of the 150 kDa signal,indicative for intact ADNP. By means of both a GFPSpark and Flag-tag N-terminally fused to a human ADNP expression vector,we detected wild-type ADNP together with mutant forms after introduction of patient mutations in E. coli expression systems by site-directed mutagenesis. Furthermore,we were also able to visualize endogenous ADNP with our C-terminal antibody panel in heterozygous cell lines carrying ADNP patient mutations,while the truncated ADNP mutants could only be detected with epitope-tag-specific antibodies,suggesting that addition of an epitope-tag possibly helps stabilizing the protein. However,western blotting of patient-derived hiPSCs,immortalized lymphoblastoid cell lines and post-mortem patient brain material failed to detect a native mutant ADNP protein. In addition,an N-terminal immunoprecipitation-competent ADNP antibody enriched truncating mutants in overexpression lysates,whereas implementation of the same method failed to enrich a possible native mutant protein in immortalized patient-derived lymphoblastoid cell lines. This study aims to shape awareness for critical assessment of mutant ADNP protein analysis in Helsmoortel-Van der Aa syndrome. View Publication

Viruses depend on host metabolic pathways and flaviviruses are specifically linked to lipid metabolism. During dengue virus infection lipid droplets are degraded to fuel replication and Zika virus (ZIKV) infection depends on triglyceride biosynthesis. Here,we systematically investigated the neutral lipid–synthesizing enzymes diacylglycerol O-acyltransferases (DGAT) and the sterol O-acyltransferase (SOAT) 1 in orthoflavivirus infection. Downregulation of DGAT1 and SOAT1 compromises ZIKV infection in hepatoma cells but only SOAT1 and not DGAT inhibitor treatment reduces ZIKV infection. DGAT1 interacts with the ZIKV capsid protein,indicating that protein interaction might be required for ZIKV replication. Importantly,inhibition of SOAT1 severely impairs ZIKV infection in neural cell culture models and cerebral organoids. SOAT1 inhibitor treatment decreases extracellular viral RNA and E protein level and lowers the specific infectivity of virions,indicating that ZIKV morphogenesis is compromised,likely due to accumulation of free cholesterol. Our findings provide insights into the importance of cholesterol and cholesterol ester balance for efficient ZIKV replication and implicate SOAT1 as an antiviral target. Exploring the role of neutral lipid-synthesizing enzymes in Zika virus infection using different cell culture models,inhibition of cholesterol esterification is found to impair ZIKV morphogenesis. View Publication

ABSTRACTExtracellular vesicles (EVs) and secretory factors play crucial roles in intercellular communication,but the molecular mechanisms and dynamics governing their interplay in human pluripotent stem cells (hPSCs) are poorly understood. Here,we demonstrate that hPSC?secreted milk fat globule?EGF factor 8 (MFGE?8) is the principal corona protein at the periphery of EVs,playing an essential role in controlling hPSC stemness. MFGE?8 depletion reduced EV?mediated self?renewal and survival in hPSC cultures. MFGE?8 in the EV corona bound to integrin ?v?5 expressed in the peripheral zone of hPSC colonies. It activated cyclin D1 and dynamin?1 via the AKT/GSK3? axis,promoting the growth of hPSCs and facilitating the endocytosis of EVs. Internalization of EVs alleviated oxidative stress and cell death by transporting redox and stress response proteins that increased GSH levels. Our findings demonstrate the critical role of the extracellular association of MFGE?8 and EVs in modulating the self?renewal and survival of hPSCs. View Publication

Monkeypox virus (MPV) is known to inflict injuries and,in some cases,lead to fatalities in humans. However,the underlying mechanisms responsible for its pathogenicity remain poorly understood. We investigated functions of MPV core proteins,H3L,A35R,A29L,and I1L,and discovered that H3L induced transcriptional perturbations and injuries. We substantiated that H3L upregulated IL1A expression. IL1A,in consequence,caused cellular injuries,and this detrimental effect was mitigated when countered with IL1A blockage. We also observed that H3L significantly perturbed the transcriptions of genes in cardiac system. Mechanistically,H3L occupied the promoters of genes governing cellular injury,leading to alterations in the binding patterns of H3K27me3 and H3K4me3 histone marks,ultimately resulting in expression perturbations. In vivo and in vitro models confirmed that H3L induced transcriptional disturbances and cardiac dysfunction,which were ameliorated when IL1A was blocked or repressed. Our study provides valuable insights into comprehensive understanding of MPV pathogenicity,highlights the significant roles of H3L in inducing injuries,and potentially paves the way for the development of therapeutic strategies targeting IL1A. View Publication