Biology subjects

Chen, M.

Publications and source records attributed to Chen, M..

At least 397 records · Page 22Linked to original sources

bioRxiv2021

METTL3 facilitates hepatic fibrosis progression via m6A-YTHDF2 dependent silencing of GPR161

Hepatic fibrosis (HF) is a very common condition seen in millions of patients with various liver diseases. N6-methyladenosine (m6A) plays critical roles in various biological and pathological processes. However, the role of m6A and its main methyltransferase METTL3 in HF remains obscure. Here, we reported that METTL3 expression was elevated in HSCs from CCl4 induced fibrotic liver. METTL3 knockdown in HSCs mediated by recombinant adeno-associated-virus serotype 9 packed short hairpin RNA against METTL3 alleviated liver injury and fibrosis compared to empty carrier group. Mechanistically, the decreased liver fibrosis in CCl4-treated HSC-specific METTL3 knockdown mice was due to the increased GPR161 that is a suppressor of Hedgehog pathway, a well-known pathway to activate in liver injury and regeneration. As expect, GPR161 transferred into HSCs alleviated liver fibrosis and HSC activation. Forced GPR161 expression inhibited Gli3 activated form nuclear accumulation and subsequently suppressed fibrosis-associate gene expression. Conclusion, HSC-specific deletion of METTL3 inhibits liver fibrosis via elevated GPR161 expression, which subsequently suppressed Hedgehog pathway activation and fibrosis-associated genes expression, providing novel therapeutic targets for HF therapy. Synopsis O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=196 SRC="FIGDIR/small/472749v1_ufig1.gif" ALT="Figure 1"> View larger version (78K): org.highwire.dtl.DTLVardef@1245f3aorg.highwire.dtl.DTLVardef@e7effdorg.highwire.dtl.DTLVardef@13ce319org.highwire.dtl.DTLVardef@61be8b_HPS_FORMAT_FIGEXP M_FIG C_FIG The role of RNA m6A methyltransferase METTL3 in the progression of hepatic fibrosis is unclear. Here, we reveal that suppresses m6A modification by depletion of METTL3 in Hepatic Stellate Cells (HSCs), stabilizes the GPR161 transcripts, that involved in suppressing Hedgehog signaling pathway, through YTHDF2, thereby alleviating the fibrosis feature of CCl4-induced liver injury. O_LIDisruption of m6A methyltransferases METTL3 in HSCs alleviates liver fibrosis feature. C_LIO_LIMETTL3 depletion in liver HSCs suppresses its activation by suppressing Hedgehog signaling pathway through stabilizing GPR161 transcripts in an m6A-YTHDF2 dependent manner. C_LIO_LIGPR161 activates PKA that mediates phosphorylation and degradation of full-length Gli3 (Gli3-FL) protein, then the short Gli3 (Gli3-R) translocated into the nucleus and suppresses the fibrosis associated gene transcription. C_LIO_LIThe elevated METTL3 expression is attribute to its promoter H3K27ac modification. C_LI

molecular biology↗

bioRxiv2021

SARS-CoV-2 RdRp is a versatile enzyme with proofreading activity and ability to incorporate NHC into RNA by using diphosphate form molnupiravir as a substrate

The coronavirus disease 2019 (COVID-19) has been ravaging throughout the world for more than two years and has severely impaired both human health and the economy. The causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) employs the viral RNA-dependent RNA polymerase (RdRp) complex for genome replication and transcription, making RdRp an appealing target for antiviral drug development. Here, we reveal that RdRp can recognize and utilize nucleoside diphosphates (NDPs) as a substrate to synthesize RNAs with an efficiency of about two thirds of using nucleoside triphosphates (NTPs) as a substrate. NDPs incorporation is also template-specific and has high fidelity. Moreover, RdRp can incorporate {beta}-d-N4-hydroxycytidine (NHC) into RNA while using diphosphate form molnupiravir (MDP) as a substrate. We also observed that MDP is a better substrate for RdRp than the triphosphate form molnupiravir (MTP).

molecular biology↗

bioRxiv2021

PPAR-delta acts as a metabolic master checkpoint for metastasis in pancreatic cancer

SO_SCPLOWUMMARYC_SCPLOWIn pancreatic cancer, emerging evidence suggests that PPAR-{delta} overexpression is associated with tumor progression and metastasis, but a mechanistic link is still missing. Here we now show that PPAR-{delta} acts as the integrating upstream regulator for the metabolic rewiring, which is preceding the subsequent initiation of an invasive/metastatic program. Specifically, paracrine and metabolic cues regularly found in the metastasis-promoting tumor stroma consistently enhance, via induction of PPAR-{delta} activity, the glycolytic capacity and reserve of pancreatic cancer cells, respectively, accompanied by decreased mitochondrial oxygen consumption. Consequently, genetic or pharmacological inhibition of PPAR-{delta} results in reduced invasiveness and metastasis. Mechanistically, PPAR-{delta} acts by shifting the MYC/PGC1A balance towards MYC, enhancing metabolic plasticity. Targeting MYC similarly prevents the metabolic switch and subsequent initiation of invasiveness. Therefore, our data demonstrate that PPAR-{delta} is a key initiator for the metabolic reprogramming in pancreatic cancer, thereby acting as a checkpoint for the phenotypic change towards invasiveness. These findings provide compelling evidence for a novel treatment strategy to combat pancreatic cancer progression.

cancer biology↗

bioRxiv2021

α-Synuclein pre-formed fibrils induce prion-like protein aggregation and neurotoxicity in C. elegans models of Parkinson's disease

Parkinsons disease (PD) is a debilitating neurodegenerative disorder characterized by progressive motor decline and the aggregation of -synuclein protein. Growing evidence suggests that -synuclein aggregates may spread from neurons of the digestive tract to the brain in a prion-like manner. While rodent models have recapitulated gut-to-brain -synuclein transmission, animal models that are amenable to high-throughput investigations are needed to facilitate the discovery of disease mechanisms. Here we describe the first C. elegans models in which feeding with -synuclein pre-formed fibrils (PFFs) induced prion-like dopamine neuron degeneration and seeding of aggregation of human -synuclein expressed in the host. PFF acceleration of -synuclein aggregation in C. elegans muscle cells was associated with a progressive motor deficit, whereas feeding with -synuclein monomer produced much milder effects. RNAi-mediated knockdown of the C. elegans syndecan sdn-1, and enzymes involved in heparan sulfate proteoglycan biosynthesis, afforded protection from PFF-induced seeding of aggregation and toxicity, as well as dopaminergic neurodegeneration. This work offers new models by which to investigate gut-derived -synuclein spreading and propagation of disease.

neuroscience↗

bioRxiv2021

PHOSPHATE STARVATION RESPONSE enables arbuscular mycorrhiza symbiosis

Arbuscular mycorrhiza (AM) is a widespread symbiosis between roots of the majority of land plants and Glomeromycotina fungi. AM is important for ecosystem health and functioning as the fungi critically support plant performance by providing essential mineral nutrients, particularly the poorly accessible phosphate, in exchange for organic carbon. AM fungi colonize the inside of roots and this is promoted at low but inhibited at high plant phosphate status, while the mechanistic basis for this phosphate-dependence remained obscure. Here we demonstrate that a major transcriptional regulator of phosphate starvation responses in rice PHOSPHATE STARVATION RESPONSE 2 (PHR2) regulates AM. Root colonization of phr2 mutants is drastically reduced, and PHR2 is required for root colonization, mycorrhizal phosphate uptake, and yield increase in field soil. PHR2 promotes AM by targeting genes required for pre-contact signaling, root colonization, and AM function. Thus, this important symbiosis is directly wired to the PHR2-controlled plant phosphate starvation response.

plant biology↗

bioRxiv2021

De-noising Spatial Expression Profiling Data Based on in situ Position and Image Information

Spatial transcriptomics (ST) technologies provide gene expression close to or even superior to single-cell resolution while retaining the physical locations of sequencing and often also providing matched pathology images. However, the expression data captured by ST technologies suffer from high noise levels, as a result of the shallow coverage in each sequencing unit. The extra experimental steps for preserving the spatial locations of sequencing could result in even more severe noises, compared to regular single-cell RNA-sequencing (scRNA-seq). Fortunately, such noises could be largely removed by leveraging information from the physical locations of sequencing, and the tissue and cellular organization reflected by corresponding pathology images. In this work, we demonstrated the extensive levels of noise in ST data. We developed a mathematical model, named Sprod, to impute accurate ST gene expression based on latent space and graph learning of matched location and imaging data. We comprehensively validated Sprod and demonstrated its advantages over prior methods for removing drop-outs in scRNA-seq data. We further showed that, after adequate imputation by Sprod, differential expression analyses, pseudotime analyses, and cell-to-cell interaction inferences yield significantly more informative results. Overall, we envision denoising by Sprod to become a key first step to empower ST technologies for biomedical discoveries and innovations.

bioinformatics↗

bioRxiv2021

Immunoglobulin-producing AT2-like cells secrete IgA into the extracellular matrix in pulmonary fibrosis

Pulmonary fibrosis is an interstitial lung disease that can be caused by various factors. Here, we first observed extensive IgA deposition in the extracellular matrix (ECM) of the lungs of mice with pulmonary fibrosis induced by silica inhalation. Consistent with this phenomenon, spatial transcriptomic sequencing of fresh mouse lung tissues from control mice and model mice showed that Igha transcripts were highly expressed in the lesion area. Single-cell RNA sequencing (scRNA-seq) and reconstruction of B cell receptor (BCR) sequences revealed a new cluster of cells with a shared BCR and high expression of genes related to immunoglobulin IgA production. Surprisingly, these clonal cells had more characteristics of AT2 (alveolar epithelial cell type 2) cells than B cells; thus, these cells were named AT2-like cells. Therefore, we propose that secretion of IgA into the ECM by AT2-like cells is an important process that occurs during lung fibrosis.

cell biology↗

bioRxiv2021

Structure Insight into Photosystem I Octamer from Cyanobacteria

Diversity of photosystem oligomers is essential to understand how photosynthetic organisms adopted to light conditions. Given by the structural and physiological significance, the assemblies of PSI supercomplex is of great interest in both chloroplast and cyanobacteria recently. In this study, two novel photosystem I supercomplexes were isolated for the first time from the low light incubated culture of filamentous cyanobacterium Anabaena sp. PCC 7120. These complexes were defined as PSI hexamers and octamers through biochemical and biophysical characterization. Their 77K emission spectra indicated that the red forms of chlorophylls seemed not to be affected during oligomerization. By cryo-EM single particle analysis, a near-atomic (7.0 [A]) resolution structure of PSI octamer was resolved, and the molecular assemblies of stable PSI octamer was revealed.

biophysics↗

bioRxiv2021

CircSry regulates spermatogenesis by enhancing γH2AX expression via sponging miR-138-5p

Sry on the Y chromosome is the master switch in sex determination in mammals. It has been well established that Sry encodes a transcription factor that is transiently expressed in somatic cells of male gonad, inducing a series of events that lead to the formation of testes. In the testis of adult mice, Sry is expressed as a circular RNA (circRNA) transcript, a type of noncoding RNA that forms a covalently linked continuous loop. However, the physiological function of this Sry circRNA (circSry) remains unknown since its discovery in 1993. Here we show that circSry is mainly expressed in the spermatocytes, but not in mature sperms and Sertoli cells. Loss of circSry led to the reduction of sperm number and the defect of germ cell development. The expression of {gamma}H2AX was decreased and failure of XY body formation was noted in circSry KO germ cells. Further study demonstrates that circSry regulates H2AX mRNA indirectly in pachytene spermatocytes through sponging miR-138-5p. Our study demonstrates that, in addition to its well-known sex-determination function, Sry also plays important role in spermatogenesis as a circRNA.

developmental biology↗

bioRxiv2021

Activation of transient receptor potential vanilloid 4 is involved in pressure overload-induced cardiac hypertrophy

Previous studies, including our own, have demonstrated that transient receptor potential vanilloid 4 (TRPV4) is expressed in hearts and implicated in cardiac remodeling and cardiac dysfunction. However, the effects of TRPV4 on pressure overload-induced cardiac hypertrophy remain unclear. In this study, we found that TRPV4 expression was significantly increased in mouse hypertrophic hearts, human failing hearts, and neurohormone-induced hypertrophic cardiomyocytes. Deletion of TRPV4 attenuated transverse aortic constriction (TAC)-induced cardiac hypertrophy, cardiac dysfunction, fibrosis, inflammation, and the activation of NF{kappa}B - NOD-like receptor pyrin domain-containing protein 3 (NLRP3) in mice. In vitro, TRPV4 inhibition decreased the neurohormone-induced cardiomyocyte hypertrophy and the increase of intracellular Ca2+ concentration. TRPV4 agonist triggered Ca2+ influx and evoked the phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) but these effects were abolished by removing extracellular Ca2+ or TRPV4 inhibition. More importantly, TAC or neurohormone stimulation-induced CaMKII phosphorylation was significantly blocked by TRPV4 inhibition. Finally, we showed that CaMKII inhibition significantly inhibited the phosphorylation of NF{kappa}B induced by TRPV4 activation. Our results suggest that TRPV4 activation contributed to pressure overload-induced cardiac hypertrophy. This effect was associated with upregulated Ca2+/ CaMKII mediated the activation of NF{kappa}B-NLRP3. Thus, TRPV4 may represent a potential therapeutic drug target for cardiac hypertrophy.

cell biology↗

bioRxiv2021

Genetic and environmental influences on the evolution of virulence in the HIV-associated opportunistic human fungal pathogen Cryptococcus neoformans

The fungus Cryptococcus neoformans is considered the leading cause of death in immunocompromised patients. Despite numerous investigations concerning its molecular epidemiology, there are only a few studies addressing the impacts of varying factors on genotype-phenotype correlations. It remains largely unknown whether genetic and environmental variabilities among isolates from different sources may have dramatic consequences on virulence. In this study, we analyzed 105 Chinese C. neoformans isolates, including 54 from HIV-infected patients, 44 from HIV-uninfected individuals and 7 from a natural environment, to investigate factors influencing the outcome of C. neoformans infection. MLST analysis clearly identified sequence type (ST) 5 as the prevalent sequence type in all clinical isolates and interestingly, genotypic diversities were observed in isolates from both HIV-uninfected individual and natural environment but not those from HIV-infected patients. Moreover, we found that compared to those from HIV-infected patients, the isolates from HIV-uninfected individuals exhibited enhanced virulence-associated traits including significantly elevated capsule production and melanin formation, increases in survival in human cerebrospinal fluid (CSF), less effective uptake by host phagocytes, and higher mortality in a mouse model of cryptococcosis. Consistently, pathogenic phenotypes were associated with CD4 counts of patients, implying environmental impact on within-host C. neoformans virulence. Importantly, a large-scale whole-genome sequencing analysis revealed that genomic variations within genes related to specific functions may act as a vital driving force of host intrinsic virulence evolution. Taken together, our results support a strong genotype-phenotype correlation suggesting that the pathogenic evolution of C. neoformans could be heavily affected by both genetic and environmental factors.

genetics↗

bioRxiv2021

Multi-parameter optical imaging of immune cell activity in chimeric antigen receptor T-cell and checkpoint blockade therapies

Longitudinal multimodal imaging presents unique opportunities for noninvasive surveillance and prediction of treatment response to cancer immunotherapy. In this work we first designed a novel granzyme B activated self-assembly small molecule, G-SNAT, for quantitative assessment of cytotoxic T lymphocyte mediated cancer cell killing in vivo. In lymphoma tumor bearing mice, the retention of cyanine 5 labeled G-SNAT-Cy5 was shown to be highly correlated to CAR T-cell mediated granzyme B release and tumor eradication. In colorectal tumor-bearing transgenic mice, expressing firefly luciferase in hematopoietic cells, and which received combination treatment of anti-PD-1 and anti-CTLA-4, longitudinal bioluminescence and fluorescence imaging revealed the dynamics of immune cell expansion, trafficking, tumor infiltration, and cytotoxic activity which predicted therapeutic outcome before tumor shrinkage was evident. These results support further development of G-SNAT for imaging early immune response to checkpoint blockade and CAR T-cell therapy in patients and highlight the utility of multimodality imaging for improved mechanistic insights into cancer immunotherapy.

immunology↗

bioRxiv2021

Astrocytes derived from ASD patients alter behavior and destabilize neuronal activity through aberrant Ca2+ signaling

The cellular mechanisms of Autism Spectrum Disorder (ASD) are poorly understood. Cumulative evidence suggests that abnormal synapse function underlies many features of this disease. Astrocytes play in several key neuronal processes, including the formation of synapses and the modulation of synaptic plasticity. Astrocyte abnormalities have also been identified in the postmortem brain tissue of ASD patients. However, it remains unclear whether astrocyte pathology plays a mechanistic role in ASD, as opposed to a compensatory response. To address this, we strategically combined stem cell culturing with transplantation techniques to determine disease specific properties inherent to patient derived astrocytes. We demonstrate that ASD astrocytes induce repetitive behavior as well as impair memory and long-term potentiation when transplanted into the healthy mouse brain. These in vivo phenotypes were accompanied by reduced neuronal network activity and spine density caused by ASD astrocytes in hippocampal neurons in vitro. Transplanted ASD astrocytes also exhibit exaggerated Ca2+ fluctuations in chimeric brains. Genetic modulation of evoked Ca2+ responses in ASD astrocytes modulates behavior and neuronal activity deficits. Thus, we determine that ASD patient astrocytes are sufficient to induce repetitive behavior as well as cognitive deficit, suggesting a previously unrecognized primary role for astrocytes in ASD.

neuroscience↗

bioRxiv2021

Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter

AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But whether AMPK activity is regulated at different subcellular locations to provide precise spatial and temporal control over metabolism is unclear. Genetically encoded AMPK activity reporters (AMPKAR) have provided a window into spatial AMPK activity, but the limited dynamic range of current AMPKARs hinders detailed study. To monitor the dynamic activity of AMPK with high sensitivity, we developed a single-fluorophore AMPK activity reporter (ExRai AMPKAR) that exhibits an excitation ratiometric fluorescence change upon phosphorylation by AMPK, with over 3-fold greater response compared to previous AMPKARs. Using subcellularly localized ExRai AMPKAR, we found that the activity of AMPK at the lysosome and mitochondria are differentially regulated. While different activating conditions, irrespective of their effects on ATP, robustly yet gradually increase mitochondrial AMPK activity, lysosomal AMPK activity accumulates with much faster kinetics. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) resulted in slower AMPK activity at lysosomes but did not affect the response amplitude at either location, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further discovered AMPK activity in the nucleus, which resulted from LKB1-mediated cytoplasmic activation of AMPK followed by nuclear shuttling. Thus, a new, sensitive reporter for AMPK activity, ExRai AMPKAR, in complement with mathematical and biophysical methods, captured subcellular AMPK activity dynamics in living cells and unveiled complex regulation of AMPK signaling within subcellular compartments.

molecular biology↗

bioRxiv2021

Progressive chromatin silencing of ABA biosynthesis gene permits seed germination in Arabidopsis

Seed germination represents a major developmental switch in plants that is vital to agricultural, but how this process is controlled at the chromatin level remains obscure. Here we demonstrate that successful germination in Arabidopsis requires a chromatin mechanism that progressively silences NCED6, which encodes a rate-limiting enzyme for abscisic acid (ABA) biosynthesis, through the cooperative action of the RNA-binding protein RZ-1 and the polycomb repressive complex 2 (PRC2). Simultaneous inactivation of RZ-1 and PRC2 blocks germination and synergistically derepresses NCEDs and hundreds of genes. At NCED6, by promoting H3 deacetylation and suppressing H3K4me3, RZ-1 facilitates transcriptional silencing and also a H3K27me3 accumulation process that occurs during seed germination and early seedling growth. Genome-wide analysis reveals RZ-1 is preferentially required for transcriptional silencing of many PRC2 targets early during seed germination when H3K27me3 is not yet established. We propose RZ-1 confers a novel silencing mechanism to compensate and coordinate with PRC2. Our work highlights the progressive chromatin silencing of ABA biosynthesis genes via synergized action of the RNA-binding protein RZ1 and PRC2, which is vital for seed germination.

plant biology↗

bioRxiv2021

Computational design of highly signaling active membrane receptors through de novo solvent-mediated allosteric networks

Protein catalysis and allostery require the atomic-level orchestration and motion of residues, ligand, solvent and protein effector molecules, but the ability to design protein activity through precise protein-solvent cooperative interactions has not been demonstrated. Here, we report the design of a dozen novel membrane receptors catalyzing G-protein nucleotide exchange through diverse de novo engineered allosteric pathways mediated by cooperative networks of intra-protein, protein-ligand and solvent molecule interactions. Consistent with the predictions, designed protein activities strongly correlated with the level of solvent-mediated interaction network plasticity at flexible transmembrane helical interfaces. Several designs displayed considerably enhanced thermostability and activity compared to related natural receptors. The most stable and active variant crystallized in an unforeseen signaling active conformation, in excellent agreement with the design models. The allosteric network topologies of the best designs bear limited similarity to those of natural receptors and reveal a space of allosteric interactions larger than previously inferred from natural proteins. The approach should prove useful for engineering proteins with novel complex protein catalytic and signaling activities.

biophysics↗

bioRxiv2021

Metformin modulates microbiota-derived inosine and ameliorates methamphetamine-induced anxiety and depression-like withdrawal symptoms in mice

ObjectiveMetformin exhibits therapeutic potential in behavioural deficits induced by methamphetamine (METH) in rats. Emerging studies suggest gut microbiota may impact psychiatric symptoms, but there is no direct evidence supporting metformins participation in the pathophysiology of withdrawal symptoms via modulation of gut microbiota. MehodsIn order to define the functional contributions by gut microbiota and metformin to the behavioural deficits during METH withdrawal, we utilized a combination of fecal microbiota transplantation (FMT), high-throughput sequencing, and untargeted metabolomics technologies. ResultsFirst, METH addicts exhibited higher diversity and distinct microbial structures compared to heathy controls. In particular, the relative abundance of Rikenellaceae was positively correlated with the severity of anxiety and depression. Second, both human-to-mouse and mouse-to-mouse FMTs confirmed that METH-altered-microbiota transplantation is sufficient to promote anxiety and depression-like behaviours in recipient germ-free mice, and these behavioural disturbances could be ameliorated by metformin. In-depth analysis revealed that METH significantly altered the bacterial composition and structure as well as relative abundance of several bacterial taxa and metabolites, including Rikenellaceae and inosine, respectively, whereas add-on metformin could remodel these alterations. Finally, the inosine complementation successfully restored METH-induced anxiety and depression-like behaviours in mice. DiscussionThis study demonstrates that METH withdrawal-induced anxiety and depression-like behaviours are convertible and transmissible via gut microbiota in a mouse model. The therapeutic effects of metformin on psychiatric manifestations are associated with microbiota-derived metabolites, highlighting the role of the gut microbiota in substance use disorders and the pathophysiology of withdrawal symptoms. Study HighlightsO_ST_ABSWhat is known?C_ST_ABSO_LIThere are no targeted therapies for substance withdrawal syndrome, but there is considerable evidence that withdrawal-associated psychiatric manifestations contribute to the poor adherence to rehabilitation treatment as well as the relapse rates. C_LIO_LIMetformin has shown its therapeutic potential against METH-induced neurobehavioural changes and neurodegeneration in rats through CREB/BDNF and Akt/GSK3 signaling pathways in the anxiety-related brain nuclei. C_LI What is new here?O_LIMETH withdrawal-induced anxiety and depression-like behaviours are convertible and transmissible via gut microbiota in a mouse model. C_LIO_LIThe therapeutic effects of metformin on psychiatric manifestations are associated with microbiota derived metabolites. C_LIO_LIInosine complementation could restore METH withdrawal-induced anxiety and depression-like behaviours. C_LI

animal behavior and cognition↗

bioRxiv2021

Enhanced Production of Mesencephalic Dopaminergic Neurons from Lineage-Restricted Human Undifferentiated Stem Cells

The differentiation of human pluripotent stem cells (hPSCs) into mesencephalic dopaminergic (mesDA) neurons requires a precise combination of extrinsic factors that recapitulates the in vivo environment and timing. Current methods are capable of generating authentic mesDA neurons after long-term culture in vitro; however, when mesDA progenitors are transplanted in vivo, the resulting mesDA neurons are only minor components of the graft. This low yield hampers the broad use of these cells in the clinic. In this study, we genetically modified pluripotent stem cells to generate a novel type of stem cells called lineage-restricted undifferentiated stem cells (LR-USCs), which robustly generate mesDA neurons. LR-USCs are prevented from differentiating into a broad range of nondopaminergic cell types by knocking out genes that are critical for the specification of cells of alternate lineages. Specifically, we target transcription factors involved in the production of spinal cord and posterior hindbrain cell types. When LR-USCs are differentiated under caudalizing condition, which normally give rise to hindbrain cell types, a large proportion adopt a midbrain identity and develop into authentic mesDA neurons. We show that the mesDA neurons are electrophysiologically active, and due to their higher purity, are capable of restoring motor behavior eight weeks after transplantation into 6-hydroxydopamine (6-OHDA)-lesioned rats. This novel strategy improves the reliability and scalability of mesDA neuron generation for clinical use.

neuroscience↗