Biology subjects

Ran, Y.

Publications and source records attributed to Ran, Y..

At least 19 recordsLinked to original sources

bioRxiv2026

Syndecan-4 exerts canonical heparan sulfate-dependent and noncanonical heparan sulfate-independent functions that regulate Aβ amyloid homeostasis

Background Heparan sulfate (HS) and heparan sulfate proteoglycans (HSPGs) are components of the amyloid deposits in Alzheimers disease (AD) and other amyloidoses. HS and HSPGs are canonically thought to facilitate amyloid deposition by accelerating the aggregation of amyloidogenic proteins and impairing their clearance in a HS-dependent manner. Methods Leveraging insights from large-scale proteomic data, we focused on Syndecan-4 (Sdc4), the most increased transmembrane HSPG in the AD brain and in the brain of A{beta} amyloid depositing mice. We used proximity ligation assays (PLA) to evaluate the association of Sdc4 with A{beta} in situ and assessed the impacts of the Sdc4 ectodomain on A{beta} aggregation in vitro. Overexpression studies in cells, hiPSC-derived neurons, and mouse organotypic brain slice cultures (OBSCs) coupled with structure-function studies were used to investigate impacts on A{beta} production and APP processing. Finally, effects of overexpression of Sdc4 in vivo in the CRND8 amyloid deposition model were evaluated. Results Consistent with canonical roles, PLA demonstrated a spatial association of Sdc4 with amyloid deposits, and in vitro, the Sdc4 ectodomain accelerated A{beta} fibril formation in a HS-dependent manner. Unexpectedly, Sdc4 overexpression reduced A{beta} production in CHO cells, hiPSC-derived neurons, and OBSCs. These effects were accompanied by dramatic decreases in the levels of sAPP and C83 and increased immature APP in the cell. Sdc4 promoted altered APP localization into detergent resistant membrane domains and increased APP association with ATG5+/LC3+/Cathepsin D+ vesicles. Structure-function studies revealed that the transmembrane region mediates these effects in a glycosaminoglycan-independent manner. Sdc4 overexpression in the brain of APP mice significantly reduced amyloid deposition at an early age. Conclusions Sdc4 exerts paradoxical and mechanistically distinct effects that could impact AD pathogenesis differentially, potentially promoting A{beta} fibrillization extracellularly while suppressing APP processing and A{beta} production. Such data challenge the prevailing view that increased levels of HSPGs in AD are always pro-amyloidogenic and identify Sdc4 as a previously unrecognized regulator of amyloid homeostasis in AD.

neuroscience↗

bioRxiv2026

LIFU-Responsive Nanocomplexes Deliver PDGF-BB mRNA for Plaques Stabilization via Neovascularization Modulation

BackgroundPathological intraplaque neovascularization, vascular leakage, and fibrous cap thinning contribute to vulnerable atherosclerotic plaque rupture. Platelet- derived growth factor-BB (PDGF-BB) has been shown to promote pericyte recruitment, thereby stabilizing the microvascular structure, and to induce phenotypic modulation of vascular smooth muscle cells (VSMCs), which enhances fibrous cap thickness and reinforces plaque stability. Nevertheless, systemic protein delivery is limited by rapid clearance and potential off-target effects. MethodsWe developed PDGF-BB mRNA-loaded lipid nanoparticle-poly(lactic-co- glycolic acid) nanobubble complexes (LNPmRNA@PLGA) and used low-intensity focused ultrasound (LIFU) to enhance plaque-targeted delivery. Cellular uptake, PDGF- BB expression, vascular mural-cell responses, plaque histology, hemodynamics, and proteomic changes were evaluated in vitro and in ApoE-/-Fbn1C1041G+/- mice. ResultsLIFU enhanced nanocomplex uptake and PDGF-BB expression, promoted vascular smooth muscle cell proliferation, migration, and phenotypic switching, and increased pericyte coverage. In vivo, LIFU plus LNPmRNA@PLGA reduced the plaque vulnerability index by 78.2% and the neovascularization area by 67.3% compared with controls, while increasing collagen deposition and improving carotid hemodynamics. ConclusionsLIFU-responsive delivery of PDGF-BB mRNA stabilized vulnerable plaques by promoting neovessel maturation and strengthening the fibrous cap. This strategy provides a spatially controlled framework for therapeutic remodeling of high-risk atherosclerotic plaques. Research Perspective What New Question Does This Study Raise?O_LICan spatially controlled PDGF-BB mRNA delivery simultaneously mature intraplaque neovessels and reinforce the fibrous cap without the systemic effects associated with recombinant PDGF-BB? C_LI What Question Should Be Addressed Next?O_LIFuture studies should define the therapeutic window, durability, and long-term safety of LIFU-triggered PDGF-BB mRNA delivery in large-animal models that more closely reproduce human plaque rupture. C_LI

pharmacology and toxicology↗

bioRxiv2025

Chronic stress abnormalize microglial-vascular interaction via AT1R signaling and microglia activation to drive depression-like behaviors

Depression entails a range of pathological processes in the brain, typically characterized by microglia activation, neural dysfunction, and vascular dysregulation. While it is well established that activated microglia inflict damage to neurons through direct and indirect microglia-neuron interactions, their interaction with vasculature and the associated regulation of vascular structure and function in depression remain poorly understood. Here, using a mouse model of depression induced by chronic unpredictable stress (CUS), we find that in stressed mice, activated microglia present reduced motility and decreased contact area with vasculature, which is accompanied by pathological vascular structure and function, marked by reduced vessel density, narrowed vascular diameters, and sluggish blood flow velocity. We observe that vascular structure in the stressed mice is rapidly modified by the vascular-contacted microglia. These vascular-contacted microglia show upregulated angiotensin II type 1 receptor (AT1R) expression, which is not present in the vascular-uncontacted microglia. Furthermore, we demonstrate that AT1R signaling together with microglia activation under chronic stress are critical mediators for the altered microglial-vascular contact situation, vascular dysregulation, as well as the depression-like behaviors. Together, our findings reveal that under CUS, the aberrant microglial-vascular interaction, including the dysregulated microglial vasoregulation arising from AT1R signaling and microglia activation, leads to depression, forging a new link between chronic stress and depression.

neuroscience↗

bioRxiv2025

Lineage Tracing Reveals a Shared Cellular Origin for Supraclavicular Brown and Inguinal Beige Adipocytes

The metabolic importance of brown adipose tissue (BAT) has been recognized, but the origins of BAT, particularly supraclavicular BAT (scBAT), are less clear. Here, we traced the origin of scBAT to Mef2c-anterior heart field (AHF)-marked cells. Mef2c-AHF-marked cells isolated from scBAT can spontaneously differentiate into brown adipocytes, express mesenchymal stem cell markers, and can be isolated from the stromal-vascular fraction (SVF) of wild-type scBAT as [CD31-CD45-SCA-1+CD29+CD34-CD24-] (CD34-) cells. Mef2c-AHF-marked cells substantially overlap with Prrx1-marked cells in scBAT, which also contribute to beige adipocytes in inguinal white adipose tissue (iWAT) during development. Similarly, CD34- cells isolated from the SVF of iWAT can spontaneously differentiate into beige adipocytes in vitro. Using intersectional tracing, we revealed that common progenitors of Mef2c-AHF- and Prrx1-marked cells in scBAT emerge from the developing heart. Thus, these studies reveal a common origin for scBAT and cardiac tissue and a close lineage relationship between scBAT and beige adipocytes of the iWAT.

developmental biology↗

bioRxiv2025

Self-Reactive B Cells in Artery Tertiary Lymphoid Organs Encode Pathogenic High Affinity Autoantibody in Atherosclerosis

Artery tertiary lymphoid organs (ATLOs) emerge in atherosclerosis which is a chronic inflammatory artery disease with an autoimmune component. However, whether disease-relevant autoimmune B cells emerge in ATLOs and their impacts remains unknown. To map atherosclerosis-specific humoral autoimmunity and define its roles, we isolated germinal-center (GC) B cells from ATLOs and lymph-nodes, expression-cloned 60 autoantibodies and screened them for arterial wall reactivity. ATLO-derived autoantibodies markedly skewed to atherosclerosis-relevant autoantigens versus those of lymph-nodes. One ATLO GC-derived autoantibody bound to histone 2B (H2B) with high-affinity ([~]25 nM). Moreover, vaccination with H2B or adoptive transfer of its cognate autoantibody markedly accelerated atherosclerosis suggesting that ATLOs fail to delete pathogenic high-affinity self-reactive B cells. In a human cohort, total circulating anti H2B antibody titers positively correlated with aortic and coronary artery calcification. We conclude that ATLOs harbor a dysregulated immune tolerance environment permissive for autoreactive B cells that express pathogenic autoantibodies driving atherosclerosis.

immunology↗

bioRxiv2025

Organism-wide spatiotemporal profiling of gene expression utilizing a X-CreERT2/Ai9 tracing system

This study utilizes a novel inducible X-CreERT2/Ai9 system to comprehensively delineate the spatial expression landscape of Fermt2, which encodes a key focal adhesion protein Kindlin-2, across organs in mice. We can confirm all known Kindlin-2-expressing cells and identify any previously unknown Kindlin-2-expressing cells and those that do not express Kindlin-2 in all tissues/organs in mice. We have developed this cost-effective, rapid, and high-fidelity system and implemented its first whole-organism application for comprehensive gene expression profiling. This work not only provides unprecedented insights into roles of Kindlin-2 in diverse physiologies and pathologies, but also establishes the inducible X-CreERT2/Ai9 system as a powerful paradigm-shifting platform for organism-wide pan-organ spatiotemporal expression profiling of any target genes encoding any proteins and micro-RNAs. By enabling high-resolution mapping of drug target expression, this system may lay critical groundwork for elucidating previously unknown adverse and beneficial effects of targeted therapies, offering transformative potential for precision medicine.

biochemistry↗

bioRxiv2025

Visible-Light-Controlled Residue-Selective Cross-Linking for Deciphering Protein Complexes and Dynamic Protein-Protein Interactions in Live Cells

Cross-linking mass spectrometry (XL-MS) has emerged as an attractive technology for investigating protein complexes and protein-protein interactions (PPIs). However, commonly used cross-linking strategies present significant challenges for precise analysis of protein complexes and dynamic PPIs in native biological environments. Here we present the visible-light-controlled lysine-selective cross-linking (VL-XL) strategy for in-depth analysis of protein complexes and dynamic PPIs both in vitro and in live cells, building on light-induced primary amines and o-nitrobenzyl alcohols cyclization (PANAC) chemistry. We demonstrate that the VL-XL strategy effectively explores the dynamic dimerization of PD-L1 stimulated by exogenous modulators. Moreover, the VL-XL strategy successfully profiles the time-resolved EGF-stimulated EGFR interactome, providing valuable insights into the regulatory mechanisms of EGFR signaling and intracellular trafficking. Importantly, the VL-XL strategy efficiently deciphers the molecular glue (MG) induced dynamic PPIs and substrate profile of MG degrader, opening an innovative avenue for identifying neo-substrates. By harnessing the advantages of temporal controllability, good biocompatibility, and lysine selectivity, the VL-XL method simplifies MS data analysis and facilitates the acquisition of accurate structural information of protein complexes and the elucidation of elusive PPIs in live cells. Overall, the VL-XL strategy expands the XL-MS toolbox, and realizes in-depth analysis of protein complexes and dynamic PPIs, which will inspire innovative solutions for protein interactomes research and structural systems biology.

biochemistry↗

bioRxiv2024

Regulation of Fungal Morphology, Conidiogenesis and Violet Pigment Synthesis by the Betalain Biosynthesis Pathway Genes in Aspergillus sydowii H-1

The biosynthesis of antioxidant pigments, namely, betalains, has predominantly been found in Caryophyllales. The potential betalains biosynthesis was firstly explored in Aspergillus sydowii H-1 under controlled culture conditions. This study identified, knocked out, and overexpressed genes involved in the betanin biosynthesis and assessed the activities of tyrosinase, 45-DOPA dioxygenase and LigB. The results indicated these betanin biosynthesis pathway was crucial for colony morphology, conidiogenesis, stress response, and violet pigment synthesis. Moreover, AsDODA and AsLigB catalyzed the conversion of L-DOPA into 45-seco-DOPA, a key intermediate in the formation of betalamic acid in vitro. Additionally, transcription factors such as AsbHLH, AsMYB1R, and AsWD40 positively regulated the expression of betalain biosynthesis genes. This research provides new insights into the evolutionary origins of betalain-producing species, expanding the scope of betalain biosynthesis to include Aspergillus species. ImportanceTo date, betalains were restricted to plants of the order Caryophyllales, fungi of Basidiomycota and several types of bacteria. This study is the first to demonstrate the potential of Ascomycetes A. sydowii H-1 to synthesize betalains under controlled culture conditions, providing a detailed genetic and biological characterization of the associated genes and metabolic pathways. This finding demonstrates that betalain biosynthesis can be expanded to other Aspergillus.

microbiology↗

bioRxiv2024

Ophiostomatoid fungi associated with bark beetles infesting Pinus armandii, with characterizations of seven new species from western China

Ophiostomatoid fungi mainly refer to the order Ophiostomatales (Ascomycota), which are known to be symbiotic with bark beetles infesting pine trees. These fungi are primarily associated with Dendroctonus armandi and other bark beetles, significantly impacting the local pines Pinus armandii in western China. However, this fungal diversity must be further explored. This study aims to identify Ophiostomatoid fungi associated with P. armandii in Ningshaan, Shaanxi Province. A total of 225 Ophiostomatalean isolates were obtained from 46 gallery samples, accounting for 77.6 % of the total number of isolated strains. Twenty species were identified based on the phylogenetic analyses of ITS, LSU, {beta}-tubulin, and EF-1, as well as morphological characteristics. These include seven new taxa, Ceratocystiopsis rugosa, Graphilbum prolificum, G. ramosus, Masuyamyces huoditangensis, Ophiostoma flavescens, O. lenta, O. mediotumida, and thirteen known species. This study laid a theoretical foundation for understanding the relationship between the beetles and the ophiostomatalean fungi in the Ningshan region, China.

microbiology↗

bioRxiv2024

Ophiostomatalean fungi associated with bark beetles infesting Pinus koraiensis, including the description of Ceratocystiopsis fushunensis sp. nov. in China

Fungi of Ophiostomatales (Sordariomycetes, Ascomycota) always have a symbiotic relationship with bark beetles (Coleoptera: Scolytinae). In this study, we investigated the fungi associated with Cryphalus piceae and Hylastes sp in Fushun. Based on the four gene fragments of TUB, ITS, LSU, and TEF and morphological characteristics, 206 strains of Ophiostomatales were identified to be distributed in 21 taxa; these included an undescribed taxon. Here, we described it as Ceratocystiopsis fushunensis sp. nov. The results of this study provided valuable information on the relationship between fungi and bark beetles.

microbiology↗

bioRxiv2024

Two new species of Graphium (Microascales, Ascomycota) associated with pine-infesting bark beetles in China

Graphium is a genus of fungi that falls under the order Microascales of Ascomycota. Some species in this genus can establish a unique symbiotic relationship with the pine-infesting bark beetles, while others are typically found in wood or soil habitats. To comprehensively investigate the diversity of species of these fungi, recent field trips were conducted in seven provinces (Fujian, Guangdong, Guizhou, Guangxi, Liaoning, Shaanxi, and Shandong) in China. 96 pure isolates of Graphium were obtained by sequences from 361 samples. Nineteen representative strains were carefully selected to generate sequencing data from four gene regions (ITS, LSU, EF1A and TUBB), then used to construct phylogenetic trees for the genus. The results revealed the discovery of two new species, namely G. armandii sp. nov. and G. massoniana sp. nov., and G. pseudoumiticum was the most common species in various pine hosts.

microbiology↗

bioRxiv2024

Optimization of gene knockout approaches and practical solutions to sgRNA selection challenges in hPSCs with inducible Cas9 system

RationaleCRISPR/Cas9 has been extensively used to knock out genes, allowing the study of genetic loss-of-function in human pluripotent stem cells (hPSCs). However, the current use of the Cas9-sgRNA plasmid or iCas9 system for gene editing in hPSCs has resulted in limited and inconsistent editing efficiency, as well as labor-intensive work. Additionally, identifying single-guide RNAs (sgRNAs) with high cleavage efficiency and distinguishing them from ineffective ones, which efficiently induce frameshift INDELs (Indels and Deletions) but fail to eliminate target proteins expression, are major challenges in gene knockout experiments. MethodsThis study addresses above issues using an optimized doxycycline-induced spCas9-expressing hPSCs (hPSCs-iCas9) system. We initially developed this system by optimizing a number of parameters to maximize INDELs introducing efficiency in hPSCs-iCas9 cells. The INDELs determined by this system were then compared to predicted scores from three cleavage efficiency scoring algorithms to validate the algorithms accuracy and consistency. Furthermore, we conducted gene knockout using a set of sgRNAs targeting different exons of the ACE2 gene to achieve approximately 80% INDELs for each targeting locus. Western blotting was then performed to detect ACE2 protein expression levels, enabling the identification of potentially ineffective sgRNAs. ResultsSeveral critical factors, including cell tolerance to nucleofection stress, sgRNA stability, nucleofection frequency, and the cell-to-sgRNA ratio, were found to have significant impact on editing efficiency in hPSCs-iCas9. Fine-tuning these parameters markedly improved this efficiency, resulting in up to 93% INDELs for single gene knockout. The three scoring algorithms exhibited significant differences or even conflicts in scoring cleavage efficiency. Through comparing experimental observations to predicted scores, we discovered that the Benchling algorithm outperformed the other two in terms of accuracy and consistency. Furthermore, a sgRNA targeting exon 2 of ACE2 gene was quickly identified as ineffective, as evidenced by the edited cells pool containing 80% INDELs while ACE2 protein expression retained unchanged detected by Western blot. ConclusionThe findings of this study offer valuable insights into the optimal design of gene knockout experiments in hPSCs and provide practical solutions to sgRNA selection challenges for gene editing.

cell biology↗

bioRxiv2024

Integrated single-cell RNA-seq analysis revealed PTN secreted by fibroblasts acting on itself and macrophages via SDC4 ligand in myocardial hypertrophy

BackgroundHypertrophic cardiomyopathy (HCM) is characterized by massive myocardial hypertrophy, which is the most frequent cause of sudden death and can lead to heart failure (HF) or stroke. The objective of this study was to explore the communication network among various cells in the heart of pathological HCM derived from transverse aortic constriction (TAC) mouse model, and investigate the potential mechanism through data mining, biological informatics analysis, and experimental validation. Methods and ResultsThe integrated analyses including CellChat, Seurat, gene ontology (GO), pseudo-time trajectory analysis, and weighted gene co-expression network analysis (WGCNA) were performed based on the single-cell RNA-seq data (scRNA-seq). In vitro tests were conducted to verify bioinformatic analysis findings through enzyme-linked immunosorbent assay (ELISA), real-time quantitative PCR (RT-qPCR), Edu staining, and transwell assay. In vivo tests were also performed to further verify bioinformatic analysis findings by western blot and immunofluorescence assays based on our established TAC mouse model with myocardial hypertrophy. Our results showed that in the heart of TAC mouse, the interaction between cardiac fibroblasts and macrophages was most common, and the increasing pleiotrophin (PTN) secreted by cardiac fibroblasts could promote themselves proliferation or invasion as well as stimulate macrophage activation to release inflammatory cytokines, such as TNF-, IL-6, Cox-2, Cd83, Egr2, and IL-10 through acting on its ligand recombinant Syndecan 4 (SDC4), which may affect cardiomyocyte normal function and eventually cause HCM. This study first demonstrated that PTN derived from cardiac fibroblasts may act on SDC4 to play crucial role in myocardial hypertrophy, which may be a potential therapeutic targets for patients with pathological HCM. ConclusionsIn this study, the complex interaction network between cardiac fibroblasts and macrophages of TAC mice based on the scRNA-seq data was investigated, and we found that the increasing PTN secreted by cardiac fibroblasts under cardiac pressure overload could promote themselves proliferation or invasion as well as stimulate macrophage activation to release inflammatory cytokines through acting on SDC4 ligand, which may affect cardiomyocyte normal function and eventually cause HCM. In addition, our study suggested that PTN derived from cardiac fibroblasts may act on SDC4 ligand to play crucial role in myocardial hypertrophy, which may be a potential therapeutic targets for patients with pathological HCM.

cell biology↗

bioRxiv2024

Sustained ON alpha retinal ganglion cells in the temporal retina exhibit task-specific regional adaptions in dendritic signal integration

Various retinal ganglion cells (RGCs) show regional adaptations, for instance, to increase visual acuity. However, for many RGC types, it is not known how they vary in their signalprocessing properties across the retina. In the mouse retina, sustained ON alpha (sON) RGCs were found to have differences in morphology and receptive field sizes along the nasotemporal axis, and temporal sON RGCs are likely to play a role in visually guided hunting. Thus, we hypothesised that this cell type also exhibits regional adaptations on the level of dendritic signal processing and that these adaptations are advantageous for prey capture. Here, we measured dendritic signals from individual sON RGCs at different locations in the exvivo whole-mount mouse retina using two-photon microscopy. We measured both postsynaptic Ca2+ signals at the dendrites of individual RGCs and presynaptic glutamate signals from bipolar cells (BCs). We found that temporal sON RGC dendrites exhibit, in addition to the expected sustained-ON signals with only weak surrounds, signals with strong surround suppression, which were not present in nasal sON RGCs. This difference was also present in the excitatory presynaptic inputs from BCs, suggesting a presynaptic origin. Finally, using population models in an encoder-decoder paradigm, we showed that these adaptations might be beneficial for detecting crickets in hunting behaviour.

neuroscience↗

bioRxiv2023

Aβ Amyloid Scaffolds the Accumulation of Matrisome and Additional Proteins in Alzheimer's Disease

We report a highly significant correlation between human Alzheimers disease (AD) brain proteome changes and those in CRND8 APP695NL/F transgenic mice. Comparing protein changes observed in the CRND8 mice with co-expression networks derived from human Alzheimers disease (AD), reveals both conserved and divergent module changes. Many proteins in the most highly conserved module (M42, matrisome) accumulate in plaques, cerebrovascular amyloid (CAA), dystrophic neuronal processes, or a combination thereof. Overexpression of two M42 proteins, midkine (Mdk) and pleiotrophin (PTN), in CRND8 mice brains leads to increased accumulation of A{beta} in plaques and in blood vessels; further, recombinant MDK and PTN enhance A{beta} aggregation into amyloid structures. Multiple M42 proteins bind to fibrillar A{beta}42 and a non-human amyloid fibril in vitro. Supporting this binding data, MDK and PTN co-accumulate with transthyretin (TTR) amyloid in the heart. Notably, our findings establish that proteomic changes in modules observed in human AD brains define an A{beta} amyloid "responsome" that is well conserved from mouse models to humans. Further, distinct amyloid structures appear to serve as scaffolds, facilitating the co-accumulation of proteins with signaling functions, and this co-accumulation may contribute to downstream pathological sequalae. Overall, this contextualized understanding of proteomic changes and their interplay with amyloid deposition provides valuable insights into the complexity of AD pathogenesis and potential biomarkers and therapeutic targets.

neuroscience↗

bioRxiv2023

DNL343 is an investigational CNS penetrant eIF2B activator that prevents and reverses the effects of neurodegeneration caused by the Integrated Stress Response

The integrated stress response (ISR) is a conserved pathway in eukaryotic cells that is activated in response to multiple sources of cellular stress. Although acute activation of this pathway restores cellular homeostasis, intense or prolonged ISR activation perturbs cell function and may contribute to neurodegeneration. DNL343 is an investigational CNS-penetrant small molecule ISR inhibitor designed to activate the eukaryotic initiation factor 2B (eIF2B) and suppress aberrant ISR activation. DNL343 reduced CNS ISR activity and neurodegeneration in a dose-dependent manner in two established in vivo models - the optic nerve crush injury and an eIF2B loss of function (LOF) mutant - demonstrating neuroprotection in both and preventing motor dysfunction in the LOF mutant mouse. Treatment with DNL343 at a late stage of disease in the LOF model reversed elevation in plasma biomarkers of neuroinflammation and neurodegeneration and prevented premature mortality. Several proteins and metabolites that are dysregulated in the LOF mouse brains were normalized by DNL343 treatment, and this response is detectable in human biofluids. Several of these biomarkers show differential levels in CSF and plasma from patients with vanishing white matter disease (VWMD), a neurodegenerative disease that is driven by eIF2B LOF and chronic ISR activation, supporting their potential translational relevance. This study demonstrates that DNL343 is a brain penetrant ISR inhibitor capable of attenuating neurodegeneration in mouse models and identifies several biomarker candidates that may be used to assess treatment responses in the clinic.

neuroscience↗

bioRxiv2023

Discovery of new deaminase functions by structure-based protein clustering

The elucidation of protein function and its exploitation in bioengineering have greatly contributed to the development of the life sciences. Existing protein mining efforts generally rely on amino acid sequences rather than protein structures due to technical difficulties in structural elucidation. We describe here for the use of AlphaFold2 to predict and subsequently cluster an entire protein family based on predicted structure similarities. We selected the deaminase family of proteins to analyze and through this approach identified many previously unknown deaminase properties. We applied these new deaminases to the development of new cytosine base editors with distinct features. Although we found many new double-stranded DNA deaminases from the DddA-like protein clade, we were surprised to find that most of the proteins in this family were not actually double-stranded DNA cytidine deaminases. From this protein clade, we engineered the smallest single-strand specific cytidine deaminase, which facilitates the first efficient cytosine base editor to be packaged into a single AAV vector. Importantly, we also profiled a deaminase from this clade that edits robustly in soybean plants, which previously suffered from poor editing by cytosine base editors. These newly discovered deaminases based on AI-assisted structural predictions greatly expand the utility of base editors for therapeutic and agricultural applications.

molecular biology↗

bioRxiv2023

U1 AMO (antisense morpholino oligos) disrupts U1 snRNP structure to promote intronic PCPA (premature cleavage and polyadenylation)

Functional depletion of U1 snRNP with a 25 nt U1 AMO (antisense morpholino oligonucleotides) may lead to intronic premature cleavage and polyadenylation (PCPA) of thousands of genes, a phenomenon known as U1 snRNP telescripting; however, the underlying mechanism remains elusive. In this study, we demonstrated that U1 AMO could disrupt U1 snRNP structure both in vitro and in vivo, thereby affecting U1 snRNP/RNAP polymerase II (RNAPII) interaction. We further showed that U1 AMO treatment might promote RNAPII disassociation with pre-mRNA in an RNA pull-down assay. By performing ChIP-seq for phosphorylation of Ser2 (Ser2P) and Ser5 (Ser5P) of the C-terminal domain (CTD) of RNA polymerase II (RNAPII), we showed that transcription elongation was disturbed upon U1 AMO treatment, with a particular high Ser2P signal at intronic cryptic polyadenylation sites (PASs). In addition, we showed that core 3 processing factors CPSF/CstF are involved in the processing of intronic cryptic PAS. Their recruitment accumulated toward cryptic PASs upon U1 AMO treatment, as indicated by ChIP-seq and iCLIP-seq analysis. Furthermore, we showed that most of these PCPAed transcripts could be exported to cytoplasm and have the potential to be translated. Conclusively, our data provide more insight into U1 snRNP telescripting, and suggest a common theme that modulation of transcription elongation may be an important mode for the regulation of mRNA polyadenylation.

molecular biology↗