Biology subjects

Fan, X.

Publications and source records attributed to Fan, X..

At least 109 records · Page 6Linked to original sources

bioRxiv2024

Thymidine Phosphorylase Promotes the Formation of Abdominal Aortic Aneurysm in Mice Fed a Western Diet

AimsThe precise molecular drivers of abdominal aortic aneurysm (AAA) remain unclear. Thymidine phosphorylase (TYMP) contributes to increased platelet activation, thrombosis, and inflammation, all of which are key factors in AAA development. Additionally, TYMP suppresses the proliferation of vascular smooth muscle cells (VSMCs), which are central to the development and progression of AAA. We hypothesize that TYMP plays a key role in AAA development. Methods and ResultsWe conducted a histological study using human AAA samples and normal abdominal aortas, revealing heightened levels of TYMP in human AAA vessel walls. To validate this observation, we utilized an Ang II perfusion-induced AAA model in wild-type C57BL/6J (WT) and Tymp-/-mice, feeding them a Western diet (TD.88137) starting from 4 weeks of age. We found that Tymp-/-mice were protected from Ang II perfusion-induced AAA formation. Furthermore, by using TYMP-expressing VSMCs as well as primarily cultured VSMCs from WT and Tymp-/- mice, we elucidated the essential role of TYMP in regulating MMP2 expression and activation. TYMP deficiency or inhibition by tipiracil, a selective TYMP inhibitor, led to reduced MMP2 production, release, and activation in VSMCs. Additionally, TYMP was found to promote pro-inflammatory cytokine expression systemically, and its absence attenuates TNF--stimulated activation of MMP2 and AKT. By co-culturing VSMCs and platelets, we observed that TYMP-deficient platelets had a reduced inhibitory effect on VSMC proliferation compared to WT platelets. Moreover, TYMP appeared to enhance the expression of activated TGF{beta}1 in cultured VSMCs in vitro and in human AAA vessel walls in vivo. TYMP also boosted the activation of thrombospondin-1 type 1 repeat domain-enhanced TGF{beta}1 signaling, resulting in increased connective tissue growth factor production. ConclusionOur findings collectively demonstrated that TYMP serves as a novel regulatory force in vascular biology, exerting influence over VSMC functionality and inflammatory responses that promote the development of AAA. Translational PerspectiveThymidine phosphorylase (TYMP) is increased in the vessel walls of patients with abdominal aortic aneurysm (AAA), and TYMP deficiency in mice reduces the incidence of AAA, suggesting that TYMP plays a crucial role in AAA development. This could be attributed to TYMPs role in enhancing systemic inflammation and thrombosis, inhibiting vascular smooth muscle cell function, increasing the activation of matrix metalloproteinase and AKT, as well as enhancing the expression of TGF{beta}1 and connective tissue growth factor. Tipiracil is an FDA-approved drug known to inhibit TYMP-enhanced thrombosis. Targeting TYMP with tipiracil could represent a promising new therapeutic strategy for AAA development.

cell biology↗

bioRxiv2024

Sec23IP recruits the Cohen syndrome factor VPS13B/COH1 to ER exit site-Golgiinterface for tubular ERGIC formation

VPS13B/COH1 is the only known causative factor for Cohen syndrome, an early-onset autosomal recessive developmental disorder with intellectual inability, developmental delay, joint hypermobility, myopia and facial dysmorphism as common features, but the molecular basis of VPS13B/COH1 in pathogenesis is unknown. Here, we identify Sec23 interacting protein (Sec23IP) at ER exit site (ERES) as a VPS13B adaptor that recruits VPS13B to ERES-Golgi interfaces. VPS13B interacts directly with Sec23IP via the VPS13 adaptor binding domain (VAB), and the interaction promotes the association between ERES and the Golgi. Disease-associated missense mutations of VPS13B-VAB impair the interaction with Sec23IP. Knockout of VPS13B or Sec23IP blocks the formation of tubular ERGIC, an unconventional cargo carrier that expedites ER-to-Golgi transport. In addition, depletion of VPS13B or Sec23IP delays ER export of procollagen, suggesting a link between procollagen secretion and joint laxity in patients with Cohen disease. Together, our study reveals a crucial role of VPS13B-Sec23IP interaction at ERES-Golgi interface in the pathogenesis of Cohen syndrome.

cell biology↗

bioRxiv2024

Evolutionary genomics of the emergence of brown algae as key components of coastal ecosystems

Brown seaweeds are keystone species of coastal ecosystems, often forming extensive underwater forests, that are under considerable threat from climate change. Despite their ecological and evolutionary importance, this phylogenetic group, which is very distantly related to animals and land plants, is still poorly characterised at the genome level. Here we analyse 60 new genomes that include species from all the major brown algal orders. Comparative analysis of these genomes indicated the occurrence of several major events coinciding approximately with the emergence of the brown algal lineage. These included marked gain of new orthologous gene families, enhanced protein domain rearrangement, horizontal gene transfer events and the acquisition of novel signalling molecules and metabolic pathways. The latter include enzymes implicated in processes emblematic of the brown algae such as biosynthesis of the alginate-based extracellular matrix, and halogen and phlorotannin biosynthesis. These early genomic innovations enabled the adaptation of brown algae to their intertidal habitats. The subsequent diversification of the brown algal orders tended to involve loss of gene families, and genomic features were identified that correlated with the emergence of differences in life cycle strategy, flagellar structure and halogen metabolism. Analysis of microevolutionary patterns within the genus Ectocarpus indicated that deep gene flow between species may be an important factor in genome evolution on more recent timescales. Finally, we show that integration of large viral genomes has had a significant impact on brown algal genome content and propose that this process has persisted throughout the evolutionary history of the lineage.

genomics↗

bioRxiv2024

Restricting CAR T Cell Trafficking Expands Targetable Antigen Space

Chimeric antigen receptor (CAR) T cells are an effective treatment for some blood cancers. However, the lack of tumor-specific surface antigens limits their wider use. We identified a set of surface antigens that are limited in their expression to cancer and the central nervous system (CNS). We developed CAR T cells against one of these antigens, LINGO1, which is widely expressed in Ewing sarcoma (ES). To prevent CNS targeting, we engineered LINGO1 CAR T cells lacking integrin 4 (A4ko), an adhesion molecule essential for migration across the blood-brain barrier. A4ko LINGO1 CAR T cells were efficiently excluded from the CNS but retained efficacy against ES. We show that altering adhesion behavior expands the set of surface antigens targetable by CAR T cells. One sentence summaryAltering integrin-mediated adhesion provides tumor selectivity to CAR T cells by preventing homing to defined normal tissues but retaining tumor trafficking and anti-tumor activity. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/579002v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@256b53org.highwire.dtl.DTLVardef@a94775org.highwire.dtl.DTLVardef@1926f62org.highwire.dtl.DTLVardef@cec52e_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Human Amniotic Epithelial Cells Promote Chx10-/Pax6+ Muller Glia Subpopulation Reprogramming into Photoreceptor-like Cells

Reprogramming Muller glia to regenerate neurons is a promising strategy for treating retinal degeneration, but whether Muller glia contain subpopulations with different regenerative fates remains unclear. Here, using single-cell RNA-seq analysis and Muller glia lineage-tracing mice with retinal degeneration, we reveal that Muller glia were heterogeneous and identify a specific Muller glial subpopulation (Chx10-/Pax6+) in healthy retinas that is activated and migrate to the outer nuclear layer (ONL) during photoreceptor degeneration. Transplantation of human amniotic epithelial cells (hAECs) facilitates the activation and extensive migration of the Chx10-/Pax6+ Muller glial subpopulation to the ONL, where they are reprogrammed into photoreceptor-like cells. Mechanistically, hAECs degrade the inhibitory extracellular matrix through regulating matrix metalloproteinases, which probably induces remodeling of the microenvironment of Muller glia and contributes to cell reprogramming. Consequently, hAEC transplantation improves visual function in rd10 mice. Our findings uncover a distinctive Muller glial subpopulation with the potential for reprogramming into photoreceptors.

cell biology↗

bioRxiv2024

A Combinatorial Strategy for HRV 3C Protease Engineering to Achieve the N-terminal Free Cleavage

Human rhinovirus 3C protease (HRV 3C-P) has a high specificity against the substrate of LEVLFQ{downarrow}G at P1 site, which plays an important role in biotechnology and academia as a fusion tag removal tool. However, a non-ignorable limitation is that an extra residue of Gly would remain at the N terminus of the recombinant target protein after cleavage with HRV 3C-P, thus potentially causing protein mis-functionality or immunogenicity. Here, we developed a combinatorial strategy by integrating structure-guided library design and high-throughput screening of eYESS approach for HRV 3C-P engineering to expand its P1 specificity. Finally, a C3 variant was obtained, exhibiting a broad substrate P1 specificity to recognize 20 different amino acids with the highest activity against LEVLFQ{downarrow}M (kcat/KM= 3.72 {+/-} 0.04 mM-1{middle dot}s-1). Further biochemical and NGS-mediated substrate profiling analysis showed that C3 variant still kept its substrate stringency at P1 site and good residue tolerance at P2 site, but with an expanded P1 specificity. Structural simulation of C3 indicated a reconstructed S1 binding pocket as well as new interactions with the substrates. Overall, our studies here prompt not only the practical applications and understanding of substrate recognition mechanisms of HRV 3C-P, also provide new tools for other enzyme engineering. Abstract graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/574269v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@b891eborg.highwire.dtl.DTLVardef@174151dorg.highwire.dtl.DTLVardef@1656f4org.highwire.dtl.DTLVardef@a6c1bb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Impact of CRISPR/HDR-editing versus lentiviral transduction on long-term engraftment and clonal dynamics of HSPCs in rhesus macaques

For precise genome editing via CRISPR/homology-directed repair (HDR), effective and safe editing of long-term engrafting hematopoietic stem cells (LT-HSCs) requires both sufficient HDR efficiency and protection of LT-HSC function and number. The impact of HDR on true LT-HSCs clonal dynamics in a relevant large animal model has not previously been studied. To track the HDR-edited cells, autologous rhesus macaque (RM) CD34+ cells were electroporated with the gRNA/Cas9 ribonucleoprotein (RNP) and HDR cassette barcode library structure and reinfused into RMs following myeloablation. For competitive model animals, fractionated CD34+ cells were transduced with a barcoded GFP-expressing lentiviral vector (LV) and electroporated via HDR machinery, respectively. CD33 knockout (KO) neutrophils were prevalent early following engraftment and then rapidly decreased, resulting in less than 1% total editing efficiency. Interestingly, in competitive animals, a higher concentration of i53 mRNA result in a less steep reduction in CD33 KO cells, presented a modest decrease in HDR rate (0.1-0.2%) and total indels (1.5-6.5%). In contrast, the drop off of LV-transduced GFP+ cells stabilized at 20% after 2 months. We next retrieved embedded barcodes and revealed that various clones contributed to early hematopoietic reconstitution, then after dominant clones appeared at steady state throughout the animals. In conclusion, CRISPR/HDR edited cells disappeared rapidly after the autologous transplantation in RM despite substantial gene editing outcome, whereas LV-transduced cells were relatively well maintained. Clonality of HDR-edited cells drastically shrank at early stage and then relied on several dominant clones, which can be mildly mitigated by the introduction of i53 mRNA.

cell biology↗

bioRxiv2023

Early Embryonic Establishment of Constitutive Heterochromatin Involves H3K14ac-mediated Recruitment of Eggless/SetDB1

Constitutive heterochromatin, built on various types of repetitive DNA, is a fundamental feature of eukaryotic nucleus essential for transposon silencing and genome stability. However, the molecular programs driving its de novo establishment during early embryogenesis remain poorly understood. Here, we show that histone H3 lysine 14 acetylation (H3K14ac) is maternally inherited and partially colocalizes with hallmarks of constitutive heterochromatin, H3 lysine 9 trimethylation (H3K9me3) and its methyltransferase Eggless/SetDB1, around the mid-blastula transition in Drosophila early embryos. Concealing H3K14ac by either antibody injection or maternal knockdown of Gcn5 diminishes Eggless/SetDB1 nuclear foci and reduces the deposition of H3K9me3. Structural analysis reveals that Eggless/SetDB1 recognizes H3K14ac via its tandem Tudor domains, and disrupting the binding interface causes defects in Eggless/SetDB1 distribution and derepression of a subset of transposons. Therefore, H3K14ac, a histone modification associated with active transcription, is a crucial piece of the maternal programs that introduce constitutive heterochromatic features to the newly formed zygotic genome.

developmental biology↗

bioRxiv2023

Exploring the Potential of Large Language Models in Molecular Tasks: An Insightful Evaluation with GPT-4

In the rapidly changing realm of artificial intelligence, large language models (LLMs) such as GPT-4 are increasingly being explored for their potential to aid and enhance the field of molecular research. This study explores the performance of GPT-4 and GPT-3.5 in molecular research, particularly in generating and optimizing molecular structures. The results highlight GPT-4s strengths in certain areas of molecular optimization, while also revealing challenges in accurately generating complex molecules. The findings underscore the necessity for integrating these models with domain-specific tools to enhance their application in scientific research, particularly in molecular studies. The study offers insights into the potential of LLMs for advancing molecular research, paving the way for future developments in this rapidly evolving field.

bioinformatics↗

bioRxiv2023

RAD-seq unravels local adaptation along a latitudinal gradient for the wild rice Zizania latifolia

The rapid climate change poses considerable threat to biodiversity by constantly alter-ing species distribution, phenotypic variation and allele frequencies. Understanding the interplay between the climate and species phenotypic and genetic variation is thus cru-cial to inform conservation strategies. In this study, we investigated local adaptation of a widespread aquatic species in China, Zizania latifolia. We performed restriction-site associated DNA sequencing (RAD-seq) for 66 wild samples composed of 10 populations, two populations in each of the five major eco-geographical regions of China and 6 cultivated samples derived from three culti-vars found in central China. We assessed genetic diversity and structure, genetic-envi-ronmental association, and genome-wide association studies for the 60 wild samples. Low levels of genetic variability were found in the Z. latifolia populations rang-ing from HE = 0.08 to HE = 1.52. Population structure showed that samples belonged to two major groups, north and south clades, split along a temperature boundary. It was estimated that the two groups diverged during the 8.2kiloyear event and later experi-enced severe genetic bottlenecks with advancement of agriculture and increase in hu-man population some 2k years later. Landscape analysis using SNP and trait data showed that environment was more important in shaping the genetic structure than geography, but the combined effect of environment and geography explained >90% of both genetic and morphological varia-tion. Several loci were found to be correlated with environmental variables as well as morphological traits, most of which were annotated as retrotransposons. Considering the abundance of transposable elements in the Z. latifolia genome, differentiation and local adaptation was inferred to be partly driven by temperature-induced transposable elements activity.

evolutionary biology↗

bioRxiv2023

Increased FAN1 expression by mRNA-LNP attenuates CAG repeat expansion in Huntington patients' iPSC-derived astrocytes

Expansion of repeat sequences within the human genome can lead to disease pathogenesis, such as Huntingtons Disease, primarily affecting the nervous system. Genome-wide association studies (GWAS) of age-at-onset in Huntingtons disease (HD) patients demonstrated DNA mismatch repair (MMR) genes are modifiers of somatic expansion and may be potential therapeutic targets for repeat expansion (RE) disorders. FAN1, a Fanconi anemia-associated nuclease, has been reported as an influencer of repeat expansion in the RE mouse models. Here, we show the first demonstration that FAN1 knock-out in HD patient-derived fibroblasts and results in increased CAG repeat length. We also develop a robust novel cell-based platform using stem cell technology to produce the HD patients iPSC-derived astrocytes (iAstro). This platform is a disease-relevant system and has a significantly wider assay window, making it more suitable to assess the effect of gene modulation on CAG repeats. A substantial and exponential increase in repeat instability was exhibited in this HD patients iPSC-derived astrocytes platform. Over-expression of FAN1 protein via FAN1 plasmid transfection in this platform reduced CAG repeat instability, suggesting that upregulation of FAN1 protein may have a potential protective effect in CAG repeat expansion for a therapeutic setting. We leveraged the mRNA-LNP modality to enhance FAN1 protein expression and revealed that codon-optimized FAN1 mRNA-LNP robustly prevented increased CAG repeat in HD patients iPSC-derived astrocytes platform. The data from these cell-based platforms highlight that FAN1 plays a protective role in attenuating expanded somatic HTT CAG repeats and shed light on new therapeutic directions against repeat expansion disorders.

neuroscience↗

bioRxiv2023

Tropism of AAV.CPP.16 in the respiratory tract and its application for a CRISPR-based gene therapy against SARS-CoV-2

Efficient gene delivery vectors are essential for developing gene therapies for respiratory diseases. Here, we report that AAV.CPP.16, a novel AAV9-derived adeno-associated virus vector, can efficiently transduce airway epithelium systems and lung parenchyma cells in both mice and non-human primates after intranasal administration. AAV.CPP.16 outperforms AAV6 and AAV9, two wild-type AAVs with demonstrated tropism to respiratory tract tissues, and can target major cell types in the respiratory tract and the lung. We also report an "all-in-one", CRISPR-Cas13d-based AAV gene therapy vector that targets the highly conserved RNA-dependent RNA polymerase (Rdrp) gene in SARS-CoV-2, and show the potential of such gene therapy against a broad range of circulating and emergent SARS-CoV-2 variants. Thus, AAV.CPP.16 could be a useful gene delivery vector for treating genetic respiratory diseases and airborne infections including for developing a potential prophilaxis to SARS-CoV-2.

bioengineering↗

bioRxiv2023

Xanthomonas citri subsp. citri type III effector PthA4 directs the dynamical expression of a putative citrus carbohydrate-binding gene for canker formation

Xanthomonas citri subsp. citri (Xcc), the causal agent of citrus canker, elicits canker symptoms in citrus plants because of the transcriptional activator-like (TAL) effector PthA4, which activates the expression of the citrus susceptibility gene CsLOB1. This study reports the regulation of the putative carbohydrate-binding protein gene Cs9g12620 by PthA4-mediated induction of CsLOB1 during Xcc infection. We found that the transcription of Cs9g12620 was induced by infection with Xcc in a PthA4-dependent manner. Even though it specifically bound to a putative TAL effector-binding element in the Cs9g12620 promoter, PthA4 exerted a suppressive effect on the promoter activity. In contrast, CsLOB1 bound to the Cs9g12620 promoter to activate its expression. The silencing of CsLOB1 significantly reduced the level of expression of Cs9g12620, which demonstrated that Cs9g12620 was directly regulated by CsLOB1. Intriguingly, PhtA4 interacted with CsLOB1 and exerted feedback control that suppressed the induction of expression of Cs9g12620 by CsLOB1. Transient overexpression and gene silencing revealed that Cs9g12620 was required for the optimal development of canker symptoms. These results support the hypothesis that the expression of Cs9g12620 is dynamically directed by PthA4 for canker formation through the PthA4-mediated induction of CsLOB1.

plant biology↗

bioRxiv2023

Structural basis for VLDLR recognition by eastern equine encephalitis virus

Alphaviruses are arthropod-borne enveloped RNA viruses that include several important human pathogens with outbreak potential. Among them, eastern equine encephalitis virus (EEEV) is the most virulent, and many survivors develop neurological sequelae, including paralysis and intellectual disability. The spike proteins of alphaviruses comprise trimers of heterodimers of their envelope glycoproteins E2 and E1 that mediate binding to cellular receptors and fusion of virus and host cell membranes during entry. We recently identified very-low density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2), two closely related proteins that are expressed in the brain, as cellular receptors for EEEV and a distantly related alphavirus, Semliki forest virus (SFV)1. The EEEV and SFV spike glycoproteins have low sequence homology, and how they have evolved to bind the same cellular receptors is unknown. Here, we used single-particle cryo-electron microscopy (cryo-EM) to determine structures of the EEEV and SFV spike glycoproteins bound to the VLDLR ligand-binding domain. The structures reveal that EEEV and SFV use distinct surfaces to bind VLDLR; EEEV uses a cluster of basic residues on the E2 subunit of its spike glycoprotein, while SFV uses two basic residues at a remote site on its E1 glycoprotein. Our studies reveal that different alphaviruses interact with the same cellular receptor through divergent binding modes. They further suggest that the ability of LDLR-related proteins to interact with viral spike proteins through very small footprints with flexible binding modes results in a low evolutionary barrier to the acquisition of LDLR-related proteins as cellular receptors for diverse sets of viruses.

microbiology↗

bioRxiv2023

Functional Trait Variations in Zizania latifolia: Insights into Climate Adaptation

The global warming could have significant impact on plant adaptation to local environments. Widespread species provides a useful model to examine the population dynamic under climate change. However, it is still unclear how widespread aquatic species response to rapidly changing environments. Wild-rice Zizania latifolia is an emergent macrophyte widely distributed across East Asia. Here, 28 Z. latifolia natural populations covering above 30 latitudes were transplanted in a common garden. The growth, photosynthesis and reproduction traits were quantified and compared among populations, and pairwise relationships among geographic and genetic variables were estimated. Results showed that, in the common garden, the high-latitude populations grew in small size indicating weaker competitiveness in warmer temperatures; the low-latitude populations had no sexual reproduction, suggesting that low-latitude individuals stood little chance to migrate successfully to higher latitude. Significant positive correlations among the distances of genetic, geographic and morphological traits for populations indicated that both isolation by distance and isolation by environment models affected the genetic pattern of populations, and phenotypic traits of Z. latifolia populations might be genetically determined. All our data suggest that Z. latifolia would be inadaptable to the global warming, indicating that this species would be at least at risk of local extinction in the warmer future.

plant biology↗

bioRxiv2023

Protein language models-assisted engineering of Uracil-N glycosylase enables programmable T-to-G and T-to-C base editing

Current base editors use DNA deamination enzymes, such as cytidine deaminase (CBE) or adenine deaminase (ABE), to facilitate transition nucleotide substitutions. Combining CBE or ABE with glycosylase enzymes, including CGBE and AYBE, can induce limited transversion mutations. Nonetheless, a critical demand remains for base editors capable of generating alternative mutation types, such as T>G corrections, which could address over 17% of monogenic SNVs responsible for human genetic diseases. In this study, we leveraged protein language models to engineer a uracil-N-glycosylase (UNG) variant with altered substrate specificities to thymines (eTDG). Notably, after only two rounds of testing fewer than 50 predicted variants, more than 50% exhibited a 1.5-11-fold enhancement in enzymatic activities, a success rate much greater than random mutagenesis. When eTDG was fused with Cas9 nickase without deaminases, it effectively induced programmable T to G or T to C substitutions and precisely corrected db/db diabetic mutation in mice (up to 55%). Our findings not only establish orthogonal strategies for developing novel base editors, but also demonstrate the capacities of protein language models for optimizing enzymes without extensive task-specific training data or laborious experimental procedures.

bioengineering↗

bioRxiv2023

Analysis the molecular similarity of least common amino acid sites in ACE2 receptor to predict the potential susceptible species for SARS-CoV-2

This research offers a bioinformatics approach to forecasting both domestic and wild animals likelihood of being susceptible to SARS-CoV-2 infection. Genomic sequencing can resolve phylogenetic relationships between the virus and the susceptible host. The genome sequence of SARS-CoV-2 is highly interactive with the specific sequence region of the ACE2 receptor of the host species. We further evaluate this concept to identify the most important SARS-CoV-2 binding amino acid sites in the ACE2 receptor sequence through the common similarity of the last common amino acid sites (LCAS) in known susceptible host species. Therefore, the SARS-CoV-2 viral genomic interacting key amino acid region in the ACE2 receptor sequence of known susceptible human host was summarized and compared with other reported known SARS-CoV-2 susceptible host species. We identified the 10 most significant amino acid sites for interaction with SARS-CoV-2 infection from the ACE2 receptor sequence region based on the LCAS similarity pattern in known sensitive SARS-CoV-2 hosts. The most significant 10 LCAS were further compared with ACE2 receptor sequences of unknown species to evaluate the similarity of the last common amino acid pattern (LCAP). We predicted the probability of SARS-CoV-2 infection risk in unknown species through the LCAS similarity pattern. This method can be used as a screening tool to assess the risk of SARS-CoV-2 infection in domestic and wild animals to prevent outbreaks of infection. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/562198v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1c77e4corg.highwire.dtl.DTLVardef@34cf43org.highwire.dtl.DTLVardef@113734forg.highwire.dtl.DTLVardef@1f763c8_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Activation of a cortical neurogenesis transcriptional program during NEUROD1-induced astrocyte-to-neuron conversion

NEUROD1-induced astrocyte-to-neuron (AtN) conversion has garnered significant attention as a potential therapeutic intervention to neurological disorders. To gain insight into the molecular regulations underlying this neuronal reprogramming process, we applied single-cell multiomics analyses on in vitro ND1-induced AtN conversion to systematically investigate how ND1 changed the fate of astrocytes at transcriptomic and epigenetic levels. Our findings reveal that the initial immature astrocytes go through an intermediate state where both astrocytic and neuronal genes are activated at early stage of AtN conversion. ND1 directly reshapes the chromatin accessibility landscape of astrocytes to that of neurons, promoting expression of endogenous Neurod1 and other neurogenic genes such as Hes6, Insm1 etc. Interestingly, cell proliferation status is highly correlated with conversion rate, and inhibition of cell division significantly reduces the conversion ratio. Moreover, in comparison with another AtN reprogramming transcription factor, ASCL1, external ND1 can activate endogenous Neurod1 and directly promote neuronal gene transcription; whereas external ASCL1 hardly activates endogenous Ascl1, leading to slower and inefficient conversion. Together, our studies demonstrate that in vitro AtN conversion mimics neurogenic transcriptional program in embryonic neurogenesis.

neuroscience↗