Biology subjects

Liu, Y.

Publications and source records attributed to Liu, Y..

At least 1,585 records · Page 88Linked to original sources

bioRxiv2023

APOE-NOTCH Axis Governs Elastogenesis During Human Cardiac Valve Remodeling

BackgroundValve remodeling is a complex process involving extracellular matrix organization, development of trilaminar structures, and physical elongation of valve leaflets. However, the cellular and molecular mechanisms regulating valve remodeling and their roles in congenital valve disorders remain poorly understood. MethodsSemilunar valves and atrioventricular valves from healthy and age-matched human fetal hearts with pulmonary stenosis (PS) were collected. Single-Cell RNA-sequencing (scRNA-seq) was performed to determine the transcriptomic landscape of multiple valvular cell subtypes in valve remodeling and disease. Spatial localization of newly-identified cell subtypes was determined via immunofluorescence and RNA in situ hybridization. The molecular mechanisms mediating valve development was investigated utilizing primary human fetal heart valve interstitial cells (VICs) and endothelial cells (VECs). ResultsscRNA-seq analysis of healthy human fetal valves identified a novel APOE+ elastin-producing VIC subtype (Elastin-VICs) spatially located underneath VECs sensing the unidirectional flow. Knockdown of APOE in fetal VICs resulted in significant elastogenesis defects. In pulmonary valve with PS, we observed decreased expression of APOE and other genes regulating elastogenesis such as EMILIN1 and LOXL1, as well as elastin fragmentation. These findings suggested the crucial role of APOE in regulating elastogenesis during valve remodeling. Furthermore, cell-cell interaction analysis revealed that JAG1 from unidirectional VECs activates NOTCH signaling in Elastin-VICs through NOTCH3. In vitro Jag1 treatment in VICs increased elastogenesis, while similar observations were found in VICs co-cultured with VECs in the presence of unidirectional flow. Notably, we found that the JAG1-NOTCH3 signaling pair was drastically reduced in the PS valves. Lastly, we demonstrated that APOE is indispensable for JAG1-induced NOTCH activation in VICs, reinforcing the presence of a synergistic intrinsic and external regulatory network involving APOE and NOTCH signaling that is responsible for regulating elastogenesis during human valve remodeling. ConclusionscRNA-seq analysis of human fetal valves identified a novel Elastin-VIC subpopulation, and revealed mechanism of intrinsic APOE and external NOTCH signaling in regulating elastogenesis during cardiac valve remodeling. These mechanisms may contribute to deciphering the pathogenesis of elastin malformation in congenital valve diseases. Clinical Perspective What Is New?O_LIHigh-resolution single-cell transcriptome atlas generated from healthy human fetal heart valves and valves affected by pulmonary stenosis during the early phase of valve remodeling prior to birth. C_LIO_LIA unique subset of valve interstitial cells (VICs) that produce elastin (Elastin-VICs) was identified. C_LIO_LIElastin-VICs specifically located underneath the valve endothelial cells (VECs) sensing unidirectional flow, and played a crucial role in elastin maturation via the expression of APOE. C_LIO_LIElastin-VICs communicated with adjacent VECs via the JAG1-NOTCH signaling, facilitating elastin formation and valve remodeling. C_LI What Are the Clinical Implications?O_LIElastin-VICs from patient valvular tissues with Pulmonary Stenosis exhibit decreased APOE-NOTCH signaling and elastin fragmentation. C_LIO_LIDirect targeting of APOE and NOTCH signaling could be a novel approach to promote elastin fiber formation and valve remodeling in patients with valvular defects. C_LI

bioinformatics↗

bioRxiv2023

Expansion of Disease Specific Cardiac Macrophages in Immune Checkpoint Inhibitor Myocarditis

BackgroundImmune checkpoint inhibitors (ICIs), antibodies targeting PD-1/PD-L1 or CTLA4 have revolutionized cancer management but are associated with devastating immune-related adverse events (irAEs) including myocarditis. The main risk factor for ICI myocarditis is the use of combination PD-1 and CTLA4 inhibition. ICI-myocarditis is often fulminant and is pathologically characterized by myocardial infiltration of T lymphocytes and macrophages. While much has been learned regarding the role of T-cells in ICI-myocarditis, little is understood regarding the identity, transcriptional diversity, and functions of infiltrating macrophages. MethodsWe employed an established murine ICI myocarditis model (Ctla4+/-Pdcd1-/- mice) to explore the cardiac immune landscape using single-cell RNA-sequencing, immunostaining, flow cytometry, in situ RNA hybridization and molecular imaging and antibody neutralization studies. ResultsWe observed marked increases in CCR2+ monocyte-derived macrophages and CD8+ T-cells in this model. The macrophage compartment was heterogeneous and displayed marked enrichment in an inflammatory CCR2+ subpopulation highly expressing Cxcl9, Cxcl10, Gbp2b, and Fcgr4 that originated from CCR2+ monocytes. Importantly, a similar macrophage population expressing CXCL9, CXCL10, and CD16 (human homologue of mouse FcgR4) was found selectively expanded in patients with ICI myocarditis compared to other forms of heart failure and myocarditis. In silico prediction of cell-cell communication suggested interactions between T-cells and Cxcl9+Cxcl10+ macrophages via IFN-{gamma} and CXCR3 signaling pathways. Depleting CD8+T-cells, macrophages, and blockade of IFN-{gamma} signaling blunted the expansion of Cxcl9+Cxcl10+macrophages in the heart and attenuated myocarditis suggesting that this interaction was necessary for disease pathogenesis. ConclusionThese data demonstrate that ICI-myocarditis is associated with the expansion of a specific population of IFN-{gamma} induced inflammatory macrophages and suggest the possibility that IFN-{gamma} blockade may be considered as a treatment option for this devastating condition.

immunology↗

bioRxiv2023

Plasma-free samples for transcriptomic analysis: a potential alternative to whole blood samples

RNA sequencing (RNAseq) technology has become increasingly important in precision medicine and clinical diagnostics and emerged as a powerful tool for identifying protein-coding genes, performing differential gene analysis, and inferring immune cell composition. Human peripheral blood samples are widely used for RNAseq, providing valuable insights into individual biomolecular information. Blood samples can be classified as whole blood (WB), plasma, serum, and remaining sediment samples, including plasma-free blood (PFB) and serum-free blood (SFB) samples. However, the feasibility of using PFB and SFB samples for transcriptome analysis remains unclear. In this study, we aimed to assess the viability of employing PFB or SFB samples as substitute RNA sources in transcriptomic analysis and performed a comparative analysis of WB, PFB, and SFB samples for different applications. Our results revealed that PFB samples exhibit greater similarity to WB samples in terms of protein-coding gene expression patterns, differential expression gene profiling, and immunological characterizations, suggesting that PFB can be a viable alternative for transcriptomic analysis. This contributes to the optimization of blood sample utilization and the advancement of precision medicine research.

bioinformatics↗

bioRxiv2023

A Mechanistic Reinterpretation of Fast Inactivation in Voltage-Gated Na+ Channels

Fast Inactivation in voltage-gated Na+ channels plays essential roles in numerous physiological functions. The canonical hinged-lid model has long predicted that a hydrophobic motif in the DIII-DIV linker (IFM) acts as the gating particle that occludes the permeation pathway during fast inactivation. However, the fact that the IFM motif is located far from the pore in recent high-resolution structures of Nav+ channels contradicts this status quo model. The precise molecular determinants of fast inactivation gate once again, become an open question. Here, we provide a mechanistic reinterpretation of fast inactivation based on ionic and gating current data. In Nav1.4 the actual inactivation gate is comprised of two hydrophobic rings at the bottom of S6. These function in series and closing once the IFM motif binds. Reducing the volume of the sidechain in both rings led to a partially conductive inactivated state. Our experiments also point to a previously overlooked coupling pathway between the bottom of S6 and the selectivity filter.

biophysics↗

bioRxiv2023

Target-identification and mechanism-of-action studies of indole terpenoid mimics reveal that proper spindle microtubule assembly is essential for Cdh1-mediated proteolysis of CENP-A

Centromere protein A (CENP-A), a histone H3 variant specific to centromeres, is crucial for kinetochore positioning and chromosome segregation. However, its regulatory mechanism in human cells remains incompletely understood. We conducted a structure-activity relationship (SAR) study of the cell cycle-arresting indole terpenoid mimic JP18 and found two more potent analogues, (+)-6-Br-JP18 and (+)-6-Cl-JP18. Tubulin was identified as a potential cellular target of these halogenated analogues by using the drug affinity responsive target stability (DARTS) based method. X-ray crystallography analysis revealed that both molecules bind to the colchicine-binding site of {beta}-tubulin. Furthermore, we discovered that treatment of human cells with microtubule-targeting agents (MTAs), including these two compounds, led to CENP-A accumulation by destabilizing Cdh1, a co-activator of the APC/C E3 ubiquitin ligase. Our study establishes a link between microtubule dynamics and CENP-A accumulation using small-molecule tools and highlights the role of Cdh1 in CENP-A proteolysis.

cell biology↗

bioRxiv2023

Introgression underlies phylogenetic uncertainty but not parallel plumage evolution in a recent songbird radiation

Instances of parallel phenotypic evolution offer great opportunities to understand the evolutionary processes underlying phenotypic changes. However, confirming parallel phenotypic evolution and studying its causes requires a robust phylogenetic framework. One such example is the "black-and-white wagtails", a group of five species in the songbird genus Motacilla: one species, the White Wagtail (M. alba), shows wide intra-specific plumage variation, while the four others form two pairs of very similar-looking species (African Pied Wagtail M. aguimp + Mekong Wagtail M. samveasnae and Japanese Wagtail M. grandis + White-browed Wagtail M. maderaspatensis, respectively). However, the two species in each of these pairs were not recovered as sisters in previous phylogenetic inferences. Their relationships varied depending on the markers used, suggesting that gene tree heterogeneity might have hampered accurate phylogenetic inference. Here, we use whole genome resequencing data to explore the phylogenetic relationships within this group, with a special emphasis on characterizing the extent of gene tree heterogeneity and its underlying causes. We first used multispecies coalescent methods to generate a "complete evidence" phylogenetic hypothesis based on genome-wide variants, while accounting for incomplete lineage sorting and introgression. We then investigated the variation in phylogenetic signal across the genome, to quantify the extent of discordance across genomic regions, and test its underlying causes. We found that wagtail genomes are mosaics of regions supporting variable genealogies, because of ILS and inter-specific introgression. The most common topology across the genome, supporting M. alba and M. aguimp as sister species, appears to be influenced by ancient introgression. Additionally, we inferred another ancient introgression event, between M. alba and M. grandis. By combining results from multiple analyses, we propose a phylogenetic network for the black-and-white wagtails that confirms that similar phenotypes evolved in non-sister lineages, supporting parallel plumage evolution. Furthermore, the inferred reticulations do not connect species with similar plumage coloration, suggesting that introgression does not underlie parallel plumage evolution in this group. Our results demonstrate the importance of investigation of genome-wide patterns of gene tree heterogeneity to help understanding the mechanisms underlying phenotypic evolution.

evolutionary biology↗

bioRxiv2023

Capsular polysaccharide-mediated protein loading onto extracellular membrane vesicles of a fish intestinal bacterium, Shewanella vesiculosa HM13

Bacterial extracellular membrane vesicles (EMVs) play various physiologically important roles mediated by cargo proteins. However, our understanding of the molecular mechanism underlying cargo loading onto EMVs is limited. In this study, we analyzed the mechanism of cargo protein loading onto EMVs from a fish intestinal Gram-negative bacterium, Shewanella vesiculosa HM13. This strain secretes EMVs carrying a major cargo protein, P49. Near the P49 gene, we found genes having homology to genes involved in protein secretion and surface polysaccharide-chain synthesis. Among them, the deletion of genes encoding homologs of a flippase involved in bacterial extracellular polysaccharide synthesis (HM3343), phosphoethanolamine transferase (HM3344), and glycerophosphodiester phosphodiesterase (HM3345) resulted in the loss of capsular polysaccharide (CPS) of EMVs. We conducted an in vitro P49 loading assay onto P49-free EMVs to examine whether P49 was loaded onto the EMVs via its interaction with the CPS of the EMVs. We found that purified P49 was loaded onto EMVs harboring CPS in vitro, whereas it was not loaded onto EMVs from the mutants lacking CPS production due to the loss of HM3343, HM3344, and HM3345. Transmission electron microscopy of EMVs loaded with P49 in vitro and in vivo showed spherical nanoparticles around the EMVs, whereas such particles were not observed for EMVs without loaded P49, implying that P49 constitutes those particles on the surface of EMVs. These results indicate that P49 is loaded onto EMVs via its interaction with the CPS of EMVs. IMPORTANCEElucidating the mechanisms of cargo loading onto bacterial extracellular membrane vesicles (EMVs) is important to understand their biogenesis and to develop their applications. Here, we show that the major cargo protein of EMVs from a fish intestinal Gram-negative bacterium, Shewanella vesiculosa HM13, is loaded onto EMVs through its interaction with capsular polysaccharide (CPS) of EMVs. Genes involved in CPS synthesis were also identified. To our knowledge, there have been no reports describing the cargo protein-loading mechanism in which CPS serves as the protein-binding scaffold for EMVs. Thus, this study represents a new mode of protein loading onto EMVs. The results deepen our understanding of cargo loading onto EMVs and would contribute to development of their applications.

microbiology↗

bioRxiv2023

A Rapid Inducible RNA Decay system reveals fast mRNA decay in P-bodies

RNA decay plays a crucial role in regulating mRNA abundance and gene expression. Modulation of RNA degradation is imperative to investigate an RNAs function. However, information regarding where and how RNA decay occurs remains scarce, partially because existing technologies fail to initiate RNA decay with the spatiotemporal precision or transcript specificity required to capture this stochastic and transient process. Here, we devised a general method that employs inducible tethering of regulatory protein factors to target RNAs and modulate their metabolism. Specifically, we established a Rapid Inducible Decay of RNA (RIDR) technology to degrade target mRNA within minutes. The fast and synchronous induction enabled direct visualization of mRNA decay dynamics in cells with spatiotemporal precision previously unattainable. When applying RIDR to endogenous ACTB mRNA, we observed rapid formation and disappearance of RNA granules, which coincided with pre-existing processing bodies (P-bodies). We measured the time-resolved RNA distribution in P-bodies and cytoplasm after induction, and compared different models of P-body function. We determined that mRNAs rapidly decayed in P-bodies upon induction. Additionally, we validated the functional role of P-bodies by knocking down specific a P-body constituent protein and RNA degradation enzyme. This study determined compartmentalized RNA decay kinetics for the first time. Together, RIDR provides a valuable and generalizable tool to study the spatial and temporal RNA metabolism in cells.

molecular biology↗

bioRxiv2023

Mechanistic characterization of a Drosophila model of paraneoplastic nephrotic syndrome

Paraneoplastic syndromes occur in cancer patients and originate from dysfunction of organs at a distance from the tumor or its metastasis. A wide range of organs can be affected in paraneoplastic syndromes; however, the pathological mechanisms by which tumors influence host organs are poorly understood. Recent studies in the fly uncovered that tumor secreted factors target host organs, leading to pathological effects. In this study, using a Drosophila gut tumor model, we characterized a mechanism of tumor-induced kidney dysfunction. Specifically, we found that Pvf1, a PDGF/VEGF signaling ligand, secreted by gut tumors activates the PvR/JNK/Jra signaling pathway in the principal cells of the kidney, leading to mis-expression of renal genes and paraneoplastic renal syndrome-like phenotypes. Our study describes a novel mechanism by which gut tumors perturb the function of the kidney, which might be of clinical relevance for the treatment of paraneoplastic syndromes.

zoology↗

bioRxiv2023

Disrupting microglial TGF-β signaling triggers region-specific pathology in the spinal cord

Transforming growth factor-{beta} (TGF-{beta}) signaling is critical for microglial maturation during development and the maintenance of microglial homeostasis in adulthood. It remains unclear whether regional susceptibilities to the loss of TGF-{beta} signaling in microglia also exist, and the contributing factors have yet to be identified. We find that deletion of Tgfbr2 on microglia leads to microglial activation and demyelination in mouse spinal cords, primarily in the dorsal column (DC). Tgfbr2-deficient microglia exhibit distinct transcriptomic changes, and those sorted from the DC display a more proinflammatory profile compared to those from the ventral column (VC) and grey matter (GM). Single nucleus RNA sequencing (snRNA-seq) of the spinal cord uncovers a microglial subtype that emerges exclusively following Tgfbr2 deletion (termed TGF{beta} signaling-suppressed microglia, TSM), exhibiting high expression of Mmp12, Gpnmb, Lgals3, Mgll, and Alcam, predominantly located in the DC. Phenotypically, disruption of microglial TGF-{beta} signaling results in behavioral deficits that are more severe in female and older mice, whereas young male mice are less affected. Mechanistically, we reveal a significantly higher level of TGF-{beta}1/TGFBR2 in the spinal cords of normal older mice compared to the young mice, with the DC region richer in genes of the TGF-{beta} signaling pathway than the VC and GM regions. This indicates that older mice and the DC region require more TGF{beta}1 to maintain tissue homeostasis and, reciprocally, are more responsive and sensitive to the disruption of TGF-{beta} signaling in microglia. Herein, we report a demyelinating disease with region-specificity and its susceptibility to the loss of microglial TGF-{beta} signaling with gender and age differences. Our findings contribute valuable information to our understanding of the importance of microglia in regulating myelin health, especially during the aging process.

neuroscience↗

bioRxiv2023

Nuclear bodies protect phase separated proteins from degradation in stressed proteome

RNA-binding proteins (RBPs) containing intrinsically disordered domains undergo liquid-liquid phase separation to form nuclear bodies under stress conditions. This process is also connected to the misfolding and aggregation of RBPs, which are associated with a series of neurodegenerative diseases. However, it remains elusive how folding states of RBPs changes upon the formation and maturation of nuclear bodies. Here, we describe SNAP-tag based imaging methods to visualize the folding states of RBPs in live cells via time-resolved quantitative microscopic analyses of their micropolarity and microviscosity. Using these imaging methods in conjunction with immunofluorescence imaging, we demonstrate that RBPs, represented by TDP-43, initially enters the PML nuclear bodies in its native state upon transient proteostasis stress, albeit it begins to misfolded during prolonged stress. Furthermore, we show that heat shock protein 70 co-enters the PML nuclear bodies to prevent the degradation of TDP-43 from the proteotoxic stress, thus revealing a previously unappreciated protective role of the PML nuclear bodies in the prevention of stress-induced degradation of TDP-43. In summary, our imaging methods described in the manuscript, for the first time, reveal the folding states of RBPs, which were previously challenging to study with conventional methods in nuclear bodies of live cells. This study uncovers the mechanistic correlations between the folding states of a protein and functions of nuclear bodies, in particular PML bodies. We envision that the imaging methods can be generally applied to elucidating the structural aspects of other proteins that exhibit granular structures under biological stimulus.

biochemistry↗

bioRxiv2023

Multiplexed Sequential Imaging in Living Cells with Orthogonal Fluorogenic RNA Aptamer/Dye Pairs

Single-cell detection of multiple target analytes is an important goal in cell biology. However, due to the spectral overlap of common fluorophores, multiplexed fluorescence imaging beyond two-to-three targets inside living cells remains a technical challenge. Herein, we introduce a multiplexed imaging strategy that enables live-cell target detection via sequential rounds of imaging-and-stripping process, which is named as "sequential Fluorogenic RNA Imaging-Enabled Sensor" (seqFRIES). In seqFRIES, multiple orthogonal fluorogenic RNA aptamers are genetically encoded inside cells, and then the corresponding cell membrane permeable dye molecules are added, imaged, and rapidly removed in consecutive detection cycles. As a proof-of-concept, we have identified in this study five in vitro orthogonal fluorogenic RNA aptamer/dye pairs (>10-fold higher fluorescence signals), four of which can be used for highly orthogonal and multiplexed imaging in living bacterial and mammalian cells. After further optimizing the cellular fluorescence activation and deactivation kinetics of these RNA/dye pairs, the whole four-color semi-quantitative seqFRIES process can now be completed in [~]20 min. Meanwhile, seqFRIES-mediated simultaneous detection of two critical signaling molecules, guanosine tetraphosphate and cyclic diguanylate, was also achieved within individual living cells. We expect our validation of this new seqFRIES concept here will facilitate the further development and potential broad usage of these orthogonal fluorogenic RNA/dye pairs for highly multiplexed and dynamic cellular imaging and cell biology studies.

bioengineering↗

bioRxiv2023

Integrating Expert Knowledge with Deep Learning Improves QSAR Models for CADD Modeling

The fusion of traditional chemical descriptors with Graph Neural Networks (GNNs) offers a compelling strategy for enhancing ligand-based virtual screening methodologies. A comprehensive evaluation revealed that the benefits derived from this integrative strategy vary significantly among different GNNs. Specifically, while GCN and SchNet demonstrate pronounced improvements by incorporating descriptors, SphereNet exhibits only marginal enhancement. Intriguingly, despite SphereNets modest gain, all three models-GCN, SchNet, and SphereNet-achieve comparable performance levels when leveraging this combination strategy. This observation underscores a pivotal insight: sophisticated GNN architectures may be substituted with simpler counterparts without sacrificing efficacy, provided that they are augmented with descriptors. Furthermore, our analysis reveals a set of expert-crafted descriptors robustness in scaffold-split scenarios, frequently outperforming the combined GNN-descriptor models. Given the critical importance of scaffold splitting in accurately mimicking real-world drug discovery contexts, this finding accentuates an imperative for GNN researchers to innovate models that can adeptly navigate and predict within such frameworks. Our work not only validates the potential of integrating descriptors with GNNs in advancing ligand-based virtual screening but also illuminates pathways for future enhancements in model development and application. Our implementation can be found at https://github.com/meilerlab/gnn-descriptor.

bioinformatics↗

bioRxiv2023

A quantitative characterization of early neuron generation in the developing zebrafish telencephalon.

The adult brain is made up of anatomically and functionally distinct regions with specific neuronal compositions. At the root of this neuronal diversity are neural stem and progenitor cells (NPCs) that produce many neurons throughout embryonic development. During development, NPCs switch from initial expanding divisions to neurogenic divisions, which marks the onset of neurogenesis. Here, we aimed to understand when NPCs switch division modes to generate the first neurons in the anterior-most part of the zebrafish brain, the telencephalon. To this end, we used the deep learning-based segmentation method Cellpose and clonal analysis of individual NPCs to assess production of neurons by NPCs in the first 24 hours of zebrafish telencephalon development. Our results provide a quantitative atlas detailing the production of telencephalic neurons and NPC division modes between 14 and 24 hours post-fertilization. We find that within this timeframe, the switch to neurogenesis is gradual, with considerable heterogeneity in individual NPC neurogenic potential and division rates. This quantitative characterization of initial neurogenesis in the zebrafish telencephalon establishes a basis for future studies aimed at illuminating the molecular mechanisms and regulators of early neurogenesis.

developmental biology↗

bioRxiv2023

Origin and early divergence of tandem duplicated sorbitol transporter genes in Rosaceae

Sorbitol is a critical photosynthate and storage substance in the Rosaceae family. Sorbitol transporters (SOTs) play a vital role in facilitating sorbitol allocation from source to sink organs and sugar accumulation in sink organs. Despite observing gene duplications in the SOT gene family, the origin and evolutionary process of these duplications are unclear, due to the complicated interplay of whole genome duplications and tandem duplications. Here, we investigated the synteny relationships of all detected Polyol/Monosaccharide Transporter (PLT) genes in 61 angiosperm genomes and SOT genes in major representative Rosaceae genomes. Combining phylogenetic analysis, we elucidated the lineage-specific expansion and syntenic conservation of PLTs and SOTs across different plant lineages. We found that Rosaceae SOTs, as PLT family members, originated from a pair of PLT tandem duplicating genes belonging to Class III-A. Additionally, lineage-specific and synergistic duplications in Amygdaloideae had contributed to the expansion of SOTs in Rosaceae plants. Overall, our findings provide insights into the genomic origins, duplication, and divergence of SOT gene family members, which are fundamental for further functional characterizations of each member.

genomics↗

bioRxiv2023

Shin in the eye: Au-CS@FNDs as contact lens additives for blocking UV irradiation, bacterial keratitis, and corneal neovascularizationtherapies

Ophthalmic disease treatment remains a significant problem globally, resulting in poor vision and blindness. UV irradiation and bacterial infection may cause severe damage to the corneal, leading to vision loss within a few days. Corneal neovascular abnormally growth that bock lights reach to eyes, causes low vision. Thus it requires urgent and efficient clinical treatment. Contact lenses play an essential role in treating ophthalmic issues. In this work, we synthesized the chitosan-stabilized Au nanoparticles with a simple method. The Au nanoparticles were further physically adsorbed with negatively charged fluorescent nanodiamonds, yielding Au-CS@FNDs. These Au-CS@FNDs particles were proven with excellent UV adsorption, antibacterial properties, and photothermal conversation ability. Furthermore, we embedded Au-CS@FNDs particles into contact lenses to prevent corneal damage from UV light and bacterial infection. Moreover, the Au-CS@FNDs embedded contact lenses were used to inhibit the neovascularization in the Human Vascular Endothelial Cells via the photodynamic effect of Au nanoparticles. To the best of our knowledge, it is the first time that gold and diamond nanoparticles were used as additives in contact lenses, aiming at clinically corneal neovascular. Our results suggest that the controllable photothermal effect of Au-CS@FNDs embedded contact lenses may provide a unique way to intervene the neovascular-induced vision loss. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/536356v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1b94b65org.highwire.dtl.DTLVardef@4f598org.highwire.dtl.DTLVardef@198058forg.highwire.dtl.DTLVardef@1950cd3_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2023

Chromatin Reprogramming of In Vitro Fertilized and Somatic Cell Nuclear Transfer Bovine Embryos During Embryonic Genome Activation

Reprogramming of the gamete into a developmentally competent embryo identity is a fundamental aspect of preimplantation development. One of the most important processes of this reprogramming is the transcriptional awakening during embryonic genome activation (EGA), which robustly occurs in fertilized embryos but is defective in most somatic cell nuclear transfer (SCNT) embryos. However, little is known about the genome-wide underlying chromatin landscape during EGA in SCNT embryos and how it differs from a fertilized embryo. By profiling open chromatin genome-wide in both types of bovine embryos, we find that SCNT embryos fail to reprogram a subset of the EGA gene targets that are normally activated in fertilized embryos. Importantly, a small number of transcription factor (TF) motifs explain most chromatin regions that fail to open in SCNT embryos suggesting that over-expression of a limited number of TFs may provide more robust reprogramming. One such TF, the zygotically-expressed bovine gene DUXC which is a homologue of EGA factors DUX/DUX4 in mouse/human, is alone capable of activating [~]84% of all EGA transcripts that fail to activate normally in SCNT embryos. Additionally, single-cell chromatin profiling revealed low intra-embryo heterogeneity but high inter-embryo heterogeneity in SCNT embryos and an uncoupling of cell division and open chromatin reprogramming during EGA. Surprisingly, our data also indicate that transcriptional defects may arise downstream of promoter chromatin opening in SCNT embryos, suggesting additional mechanistic insights into how and why transcription at EGA is dysregulated. We anticipate that our work will lead to altered SCNT protocols to increase the developmental competency of bovine SCNT embryos.

developmental biology↗

bioRxiv2023

A novel and highly specific Forssman antigen-binding protein from sheep polyomavirus

Polyomaviruses are small, non-enveloped double-stranded DNA viruses of humans and other mammals, birds, and fish. Infections are usually asymptomatic and result in latency, however, some polyomaviruses can induce severe diseases, including cancer, in immunocompromised individuals. Established cellular receptors for polyomavirus infection are sialylated glycolipids (such as gangliosides), membrane proteins, and glycosaminoglycans. Polyomaviruses are usually highly host specific but the exact principles that govern host tropism remain unknown in many cases. Here, glycan array screening shows that the major capsid protein VP1 of sheep polyomavirus (ShPyV) binds to the Forssman glycolipid, an antigen of many vertebrates and a potential tumor marker in humans. Following closer investigation, we can report for the first time that a neutral, non-sialylated glycolipid acts as a polyomavirus receptor. Concurrently, we present the first report of a viral protein that specifically engages the Forssman antigen. We demonstrate that ShPyV VP1 binds to Forssman-positive erythrocytes but not those of human A, B and O blood groups, which is a clear distinction from features thus far described for Forssman lectins. X-ray crystallography and structural analysis of the VP1-Forssman glycan complex define the terminal Forssman disaccharide as the determinant of this protein-receptor interaction. These results strongly suggest that the sheep polyomavirus can use Forssman antigen for infectious cell entry. Furthermore, the ability of ShPyV VP1 to distinguish Forssman-positive from -negative cells may prove useful for monitoring the Forssman- status of normal, preneoplastic and neoplastic cells and tissues and establishing the antigen level as a biomarker. Author summaryElucidation of host cell receptor specificities of viral infection is crucial to understand the pathobiology of associated diseases and develop treatments. However, for many polyomaviruses the receptor engagement as the initial event in infection is poorly understood. In only a few cases polyomavirus tropism has been pinned down to a single type of glycan receptor. While many polyomaviruses utilize sialyl glycans to attach to host cells, the role of non-sialylated glycans as receptors is so far underestimated. Here, we show for the first time that a glycan of neutral charge, in this case the carbohydrate portion of the Forssman antigen, acts as a ligand for a polyomavirus capsid protein and may thus contribute to host tropism and infective cell entry. These results represent a significant addition to knowledge on polyomavirus-glycan interactions and complement general principles of carbohydrate engagement by viruses. Furthermore, as a specific binding protein of Forssman antigen, VP1 may help to determine levels of this antigen in healthy and malignant tissues in humans.

biochemistry↗