Biology subjects

Yu, H.

Publications and source records attributed to Yu, H..

At least 379 records · Page 21Linked to original sources

bioRxiv2021

CHRONIC INFLAMMATION IN ULCERATIVE COLITIS CAUSES LONG TERM CHANGES IN GOBLETCELL FUNCTION

ObjectiveOne of the features of ulcerative colitis (UC) is a defect in the protective mucus layer. This has been attributed to a reduced number of goblet cells (GC). However, it is not known whether abnormal GC mucus secretion also contributes to the reduced mucus layer. Our aims were to test the hypothesis that GC secretion was abnormal in UC with the changes persistent in colonoids even in the absence of immune cells. DesignColonoids were established from intestinal stem cells of healthy subjects (HS) and from patients with UC (inactive and active sites). Colonoids were maintained as undifferentiated (UD) or induced to differentiate (DF) and studied as 3D or monolayers on Transwell filters. Total RNA was extracted for quantitative real-time PCR analysis. Carbachol and PGE2 mediated stimulation followed by examination of mucus layer by MUC2 IF/confocal microscopy and TEM were performed. ResultsColonoids derived from patients with UC can be propagated over many passages; however, they exhibit a reduced rate of growth and TEER compared with colonoids from HS. Differentiated UC colonoid monolayers form a thin and non-continuous mucus layer. UC colonoids have increased expression of secretory lineage markers: ATOH1 and SPDEF, including MUC2 positive GCs and ChgA positive enteroendocrine cells but failed to secrete mucin when exposed to the cholinergic agonist carbachol and PGE2, which caused increased secretion in HS. Exposure to TNF- (5days), reduced the number of GC with a greater percentage decrease in UC colonoids compared to HS. ConclusionsAbnormal mucus layer in UC is due to long term changes in epithelial cells that lead to abnormal mucus secretion as well as effects of the inflammatory environment to reduce the number of GC. This continued defect in GC mucus secretion may be involved in UC recurrence.

physiology↗

bioRxiv2021

Comparative genomics reveals evolutionary drivers of sessile life and left-right shell asymmetry in bivalves

Bivalves are species-rich mollusks with prominent protective roles in coastal ecosystems. Across these ancient lineages, colony-founding larvae anchor themselves either by byssus production or by cemented attachment. The latter mode of sessile life is strongly molded by left-right shell asymmetry during larval development of Ostreoida oysters such as Crassostrea hongkongensis. Here, we sequenced the genome of C. hongkongensis in high resolution and compared it to reference bivalve genomes to unveil genomic determinants driving cemented attachment and shell asymmetry. Importantly, loss of the homeobox gene antennapedia (Antp) and broad expansion of lineage-specific extracellular gene families are implicated in a shift from byssal to cemented attachment in bivalves. Evidence from comparative transcriptomics shows that the left-right asymmetrical C. hongkongensis plausibly diverged from the symmetrical Pinctada fucata in expression profiles marked by elevated activities of orthologous transcription factors and lineage-specific shell-related gene families including tyrosinases, which may cooperatively govern asymmetrical shell formation in Ostreoida oysters.

genomics↗

bioRxiv2021

Killed whole genome-reduced bacteria surface-expressed coronavirus fusion peptide vaccines protect against disease in a porcine model

As the coronavirus disease 2019 (COVID-19) pandemic rages on, it is important to explore new evolution-resistant vaccine antigens and new vaccine platforms that can produce readily scalable, inexpensive vaccines with easier storage and transport. We report here a synthetic biology-based vaccine platform that employs an expression vector with an inducible Gram-negative autotransporter to express vaccine antigens on surface of genome-reduced bacteria to enhance interaction of vaccine antigen with immune system. As a proof of principle, we utilized genome-reduced E. coli to express SARS-CoV-2 and porcine epidemic diarrhea virus (PEDV) fusion peptide (FP) on the cell surface, and evaluated their use as a killed whole cell vaccine. The FP sequence is highly conserved across coronaviruses; the 6 FP core amino acid residues along with the 4 adjacent residues upstream and the 3 residues downstream the core are identical between SARS-CoV-2 and PEDV. We tested the efficacy of PEDV FP and SARS-CoV-2 FP vaccines in a PEDV challenge pig model. We demonstrated that both vaccines induced potent anamnestic responses upon virus challenge, potentiated IFN-{gamma} responses, reduced viral RNA loads in jejunum tissue, and provided significant protection against clinical disease. However, neither vaccines elicited sterilizing immunity. Since SARS-CoV-2 FP and PEDV FP vaccines provided similar clinical protection, the coronavirus FP could be a target for a broadly-protective vaccine using any platform. Importantly, the genome-reduced bacterial surface-expressed vaccine platform, when using a vaccine appropriate bacterial vector, has potential utility as an inexpensive, readily manufactured, and rapid vaccine platform for other pathogens. Significance StatementWe report a new vaccine platform to express vaccine antigens on surface of genome-reduced bacteria to enhance vaccine immunogenicity. We demonstrated the utility of this vaccine platform by expressing the highly conserved fusion peptide (FP) of SARS-CoV-2 and porcine epidemic diarrhea virus on the surface of E.coli to produce killed whole cell bacterial vaccines. The vaccine primes a potent anamnestic response, potentiates IFN-{gamma} responses, and provides significant protection in pigs against disease following virus challenge. The FP could be a target for a broadly-protective coronavirus vaccine since a Betacoronavirus SARS-CoV-2 FP vaccine provided cross-protection against Alphacoronavirus PEDV. When using a vaccine appropriate bacteria vector, this inexpensive new vaccine platform offers the potential for use in developing countries.

microbiology↗

bioRxiv2021

Metatranscriptomic comparison of endophytic and pathogenic Fusarium-Arabidopsis interactions reveals plant transcriptional plasticity

Plants are continuously exposed to beneficial and pathogenic microbes, but how plants recognize and respond to friends versus foes remains poorly understood. Here, we compared the molecular response of Arabidopsis thaliana independently challenged with a Fusarium oxysporum endophyte Fo47 versus a pathogen Fo5176. These two Fusarium oxysporum strains share a core genome of about 46 Mb, in addition to unique 1,229 and 5,415 accessory genes. Metatranscriptomic data reveal a shared pattern of expression for most plant genes ([~]80%) in responding to both fungal inoculums at all time points from 12 to 96 h post inoculation (HPI). However, the distinct responding genes depict transcriptional plasticity, as the pathogenic interaction activates plant stress responses and suppresses plant growth/development related functions, while the endophytic interaction attenuates host immunity but activates plant nitrogen assimilation. The differences in reprogramming of the plant transcriptome are most obvious in 12 HPI, the earliest time point sampled and are linked to accessory genes in both fungal genomes. Collectively, our results indicate that the A. thaliana and F. oxysporum interaction displays both transcriptome conservation and plasticity in the early stages of infection, providing insights into the fine-tuning of gene regulation underlying plant differential responses to fungal endophytes and pathogens. One-sentence summaryMultiomics analysis reveals the regulatory plasticity of plants in response to beneficial and antagonistic microbes, resulting in distinct phenotypes and rewired transcriptional networks.

plant biology↗

bioRxiv2021

Handcuffing intrinsically disordered regions in Mlh1-Pms1 disrupts mismatch repair

The DNA mismatch repair (MMR) factor Mlh1-Pms1 contains long intrinsically disordered regions (IDRs). While essential for MMR, their exact functions remain elusive. We performed cross-linking mass spectrometry to identify the major interactions within the Mlh1-Pms1 heterodimer and used this information to insert FRB and FKBP dimerization domains into the IDRs of Mlh1 and Pms1. Yeast bearing these constructs were grown with rapamycin to induce dimerization. Strains containing FRB and FKBP domains in the Mlh1 IDR displayed complete MMR defects when grown with rapamycin, but removing rapamycin restored MMR functions. Furthermore, linking the Mlh1 and Pms1 IDRs through FRB-FKBP dimerization disrupted Mlh1-Pms1 binding to DNA, inappropriately activated Mlh1-Pms1, and caused MMR defects in vivo. We conclude that dynamic and coordinated rearrangements of the MLH IDRs regulate how the complex clamps DNA to catalyze MMR. The application of the FRB-FKBP dimerization system to interrogate in vivo functions of a critical repair complex will be useful for probing IDRs in diverse enzymes and to probe transient loss of MMR on demand.

genetics↗

bioRxiv2021

Indoleamine 2,3-dioxygenase upregulates PD-1 expression on ovarian tumor infiltrating CD8+ T cells via kynurenine activation of the aryl hydrocarbon receptor

The immunoregulatory enzyme, indoleamine 2,3-dioxygenase (IDO1) and the PD-1/PD-L1 axis are potent mechanisms that impede effective anti-tumor immunity in ovarian cancer. However, whether the IDO pathway regulates PD-1 expression in T cells is currently unknown. Here we show that tumoral IDO1 expression led to profound changes in tryptophan, nicotinate/nicotinamide, and purine metabolic pathways in the ovarian tumor microenvironment, and to an increased frequency of PD-1+CD8+ tumor infiltrating T cells. We determined that activation of the aryl hydrocarbon receptor (AHR) by kynurenine induced PD-1 expression, and this effect was significantly abrogated by the AHR antagonist CH223191. Mechanistically, kynurenine alters chromatin accessibility in regulatory regions of T cell inhibitory receptors, allowing AHR to bind to consensus XRE motifs in the promoter region of PD-1. These results enable the design of strategies to target the IDO1 and AHR pathways for enhancing anti-tumor immunity in ovarian cancer.

immunology↗

bioRxiv2021

A transient postnatal quiescent period precedes emergence of mature cortical dynamics

Mature neural networks synchronize and integrate spatiotemporal activity patterns to support cognition. Emergence of these activity patterns and functions is believed to be developmentally regulated, but the postnatal time course for neural networks to perform complex computations remains unknown. We investigate the progression of large-scale synaptic and cellular activity patterns across development using high spatiotemporal resolution in vivo electrophysiology in immature mice. We reveal that mature cortical processes emerge rapidly and simultaneously after a discrete but volatile transition period at the beginning of the second postnatal week of rodent development. The transition is characterized by relative neural quiescence, after which spatially distributed, temporally precise, and internally organized activity occurs. We demonstrate a similar developmental trajectory in humans, suggesting an evolutionarily conserved mechanism to transition network operation. We hypothesize that this transient quiescent period is a requisite for the subsequent emergence of coordinated cortical networks.

neuroscience↗

bioRxiv2021

Biomolecular recognition of the glycan neoantigen CA19-9 by distinct antibodies

Glycans decorate cell surface, secreted glycoproteins and glycolipids. Altered glycans are often found in cancers. Despite their high diagnostic and therapeutic potentials, glycans are polar and flexible molecules that are quite challenging for the development and design of high-affinity binding antibodies. To understand the mechanisms by which glycan neoantigens are specifically recognized by antibodies, we analyze the biomolecular recognition of a single tumor-associated carbohydrate antigen CA19-9 by two distinct antibodies using X-ray crystallography. Despite the plasticity of glycans and the very different antigen-binding surfaces presented by the antibodies, both structures reveal an essentially identical extended CA19-9 conformer, suggesting that this conformers stability selects the antibodies. Starting from the bound structure of one of the antibodies, we use the AbLIFT computational method to design a variant with seven core mutations that exhibited tenfold improved affinity for CA19-9. The results reveal strategies used by antibodies to specifically recognize glycan antigens and show how automated antibody-optimization methods may be used to enhance the clinical potential of existing antibodies.

molecular biology↗

bioRxiv2021

Mitochondriomics reveals the underlying neuoprotective mechanism of TrkB receptor agonist R13 in the 5xFAD mice

Decreased energy metabolism and mitochondrial biogenesis defects are implicated in the pathogenesis of Alzheimers disease (AD). In present study, mitochondriomics analysis revealed significant effects of R13, a prodrug of 7,8-dihydroxyflavone, on mitochondrial protein expression profile, including the proteins related to the biological processes: fatty acid beta-oxidation, fatty acid metabolic process, mitochondrial electron transport, and mitochondrial respiratory chain. Cluster analysis of mitochondriomics demonstrated that R13 promoted mitochondrial oxidative phosphorylation (OXPHOS). The functional analysis showed that R13 increased ATP levels and enhanced OXPHOS including complex I, complex II, complex III and complex IV. R13 treatment increased mitochondrial biogenesis by regulating the levels of p-AMPK, p-CREB, PGC-1, NRF1 and TFAM as a consequence of activation of TrkB receptor in the 5xFAD mice. Finally, R13 significantly reduced the levels of tau phosphorylation and A{beta} plaque. Our data suggest that R13 may be used for treating AD via enhancing mitochondrial biogenesis and metabolism.

pharmacology and toxicology↗

bioRxiv2021

The effect of mentee and mentor gender on scientific productivity of applicants for NIH training fellowships

Several studies have suggested that women in science are less productive than men, and that this gap contributes to their under-representation in the ranks of senior researchers. However, few studies have examined the role of mentoring, and in particular mentor gender, on the productivity of female scientists early in their careers. Such efforts are limited by the difficulties of unambiguously linking mentees to their mentors and measuring the research productivity resulting from those relationships. Here we use our novel author disambiguation solution to investigate the role of self-identified gender in mentorship of 12,932 trainees who either successfully or unsuccessfully applied to the National Institutes of Health for research fellowships between fiscal years 2011 and 2017, applying a multi-dimensional framework to assess productivity. We found that, after normalizing for the funding level of mentors, the productivity of female and male mentees is indistinguishable; it is also independent of the gender of the mentor, other than in measures of clinical impact, where women mentored by women outperform other mentee-mentor dyads.

scientific communication and education↗

bioRxiv2021

Therapeutic antibodies, targeting the SARS-CoV-2 spike N-terminal domain, protect lethally infected K18-hACE2 mice

Since the onset of the current COVID-19 pandemic, high priority is given to the development of neutralizing antibodies, as a key approach for the design of therapeutic strategies to countermeasure and eradicate the disease. Previously, we reported the development of human therapeutic monoclonal antibodies (mAbs) exhibiting very high protective ability. These mAbs recognize epitopes on the spike receptor binding domain (RBD) of SARS-CoV-2 that is considered to represent the main rout of receptor engagement by the SARS-CoV-2 virus. The recent emergence of viral variants emphasizes the notion that efficient antibody treatments need to rely on mAbs against several distinct key epitopes in order to circumvent the occurrence of therapy escape-mutants. Here we report the isolation and characterization of 12 neutralizing mAbs, identified by screening a phage-display library constructed from lymphatic cells collected from severe COVID-19 patients. The antibodies target three distinct epitopes on the spike N-terminal domain (NTD) of SARS-CoV-2, one of them defining a major site of vulnerability of the virus. Extensive characterization of these mAbs suggests a neutralization mechanism which relies both on amino-acid and N-glycan recognition on the virus, and involvement of receptors other than the hACE2 on the target cell. Two of the selected mAbs, which demonstrated superior neutralization potency in vitro, were further evaluated in vivo, demonstrating their ability to fully protect K18-hACE2 transgenic mice even when administered at low doses and late after infection. The study demonstrates the high potential of the mAbs for therapy of SARS-CoV-2 infection and underlines the possible role of the NTD in mediating infection of host cells via alternative cellular portals other than the canonical ACE2 receptor.

immunology↗

bioRxiv2021

Piezo2 mechanosensitive ion channel is located to sensory neurons and non-neuronal cells in rat peripheral sensory pathway: implications in pain

Piezo2 mechanotransduction channel is a crucial mediator of sensory neurons for sensing and transducing touch, vibration, and proprioception. We here characterized Piezo2 expression and cell specificity in rat peripheral sensory pathway using a validated Piezo2 antibody. Immunohistochemistry using this antibody revealed Piezo2 expression in pan primary sensory neurons (PSNs) of dorsal rood ganglia (DRG) in naive rats, which was actively transported along afferent axons to both central presynaptic terminals innervating the spinal dorsal horn (DH) and peripheral afferent terminals in skin. Piezo2 immunoreactivity (IR) was also detected in the postsynaptic neurons of the DH and in the motor neurons of the ventral horn, but not in spinal GFAP- and Iba1-positive glia. Notably, Piezo2-IR was clearly identified in peripheral non-neuronal cells, including perineuronal glia, Schwann cells in the sciatic nerve and surrounding cutaneous afferent endings, as well as in skin epidermal Merkel cells and melanocytes. Immunoblots showed increased Piezo2 in DRG ipsilateral to plantar injection of complete Freunds adjuvant (CFA), and immunostaining revealed increased Piezo2-IR intensity in the DH ipsilateral to CFA injection. This elevation of DH Piezo2-IR was also evident in various neuropathic pain models and monosodium iodoacetate (MIA) knee osteoarthritis (OA) pain model, compared to controls. We conclude that 1) the pan neuronal profile of Piezo2 expression suggests that Piezo2 may function extend beyond simply touch/proprioception mediated by large-sized low-threshold mechanosensitive PSNs, 2) Piezo2 may have functional roles involving sensory processing in spinal cord, Schwann cells, and skin melanocytes, and 3) aberrant Piezo2 expression may contribute pain pathogenesis.

neuroscience↗

bioRxiv2021

Sampling from Disentangled Representations of Single-Cell Data Using Generative Adversarial Networks

Deep generative models, including variational autoencoders (VAEs) and generative adversarial networks (GANs), have achieved remarkable successes in generating and manipulating highdimensional images. VAEs excel at learning disentangled image representations, while GANs excel at generating realistic images. Here, we systematically assess disentanglement and generation performance on single-cell gene expression data and find that these strengths and weaknesses of VAEs and GANs apply to single-cell gene expression data in a similar way. We also develop MichiGAN1, a novel neural network that combines the strengths of VAEs and GANs to sample from disentangled representations without sacrificing data generation quality. We learn disentangled representations of two large singlecell RNA-seq datasets [13, 68] and use MichiGAN to sample from these representations. MichiGAN allows us to manipulate semantically distinct aspects of cellular identity and predict single-cell gene expression response to drug treatment.

bioinformatics↗

bioRxiv2021

MLH1/3 variants causing aneuploidy, pregnancy loss, and premature reproductive aging

Most spontaneous pregnancy losses are a result of embryonic aneuploidy stemming from mis-segregation of chromosomes during meiosis. Proper disjunction of homologous chromosomes is dependent upon precise control of crossing-over, a process requiring the mismatch repair (MMR) genes MLH1 and MLH3. Both are required for fertility and completion of meiosis in mice. People inheriting variants in these genes are often at high risk for colorectal cancer and Lynch syndrome, yet the potential impacts of variants upon reproduction are unclear. To determine if MLH1/3 variants (namely single nucleotide polymorphisms, or SNPs) in human populations can cause reproductive abnormalities, we used a combination of computational predictions, yeast two-hybrid assays, and assays of MMR and recombination in yeast to select nine MLH1 and MLH3 variants for modeling in mice via genome editing. We identified 7 alleles that caused reproductive defects in mice including subfertility in females, male infertility, reduced sperm counts, and increased spermatocyte apoptosis. Remarkably, these alleles in females caused age-dependent decreases in litter size, and increased resorption of embryos during pregnancy. These outcomes were likely a consequence of reduced meiotic chiasmata, in turn causing an increase in misaligned chromosomes and univalents in meiotic metaphase I (MI). Our data indicate that segregating hypomorphic alleles of meiotic recombination genes in populations can predispose females to increased incidence of pregnancy loss from gamete aneuploidy.

genetics↗

bioRxiv2020

Sterilizing immunity against SARS-CoV-2 in hamsters conferred by a novel recombinant subunit vaccine

A safe and effective SARS-CoV-2 vaccine is essential to avert the on-going COVID-19 pandemic. Here, we developed a subunit vaccine, which is comprised of CHO-expressed spike ectodomain protein (StriFK) and nitrogen bisphosphonates-modified zinc-aluminum hybrid adjuvant (FH002C). This vaccine candidate rapidly elicited the robust humoral response, Th1/Th2 balanced helper CD4 T cell and CD8 T cell immune response in animal models. In mice, hamsters, and non-human primates, 2-shot and 3-shot immunization of StriFK-FH002C generated 28- to 38-fold and 47- to 269-fold higher neutralizing antibody titers than the human COVID-19 convalescent plasmas, respectively. More importantly, the StriFK-FH002C immunization conferred sterilizing immunity to prevent SARS-CoV-2 infection and transmission, which also protected animals from virus-induced weight loss, COVID-19-like symptoms, and pneumonia in hamsters. Vaccine-induced neutralizing and cell-based receptor-blocking antibody titers correlated well with protective efficacy in hamsters, suggesting vaccine-elicited protection is immune-associated. The StriFK-FH002C provided a promising SARS-CoV-2 vaccine candidate for further clinical evaluation.

microbiology↗

bioRxiv2020

INO80 promotes H2A.Z occupancy to regulate 1 cell fate transition in pluripotent stem cells

The INO80 chromatin remodeler is involved in many chromatin-dependent cellular functions. However, its role in pluripotency and cell fate transition is not fully defined. We examined the impact of Ino80 deletion in the naive and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naive state, but led to cellular differentiation and de-repression of developmental genes in the transition toward and maintenance of the primed state. Mechanistically, INO80 pre-marked gene promoters that would adopt the H3K4me3 and H3K27me3 bivalent histone modifications. It promoted H2A.Z occupancy at these future bivalent domains to facilitate H3K27me3 installation and maintenance as well as downstream gene repression. Thus, INO80-dependent H2A.Z occupancy is a critical a licensing step for bivalency and poised gene expression in pluripotent stem cells. Our results uncovered an unexpected function of INO80 in H2A.Z deposition and gene repression, and an epigenetic mechanism by which chromatin remodeling, histone variant and modification coordinately control cell fate.

developmental biology↗

bioRxiv2020

Genomic Evidence for the Chinese Mountain Cat as a Wildcat Conspecific (Felis silvestris bieti) and Its Introgression to Domestic Cats

The enigmatic Chinese mountain cat, endemic to the Qinghai-Tibet Plateau, has a controversial taxonomic status, whether a true species or conspecific with the wildcat (Felis silvestris) and whether it may have contributed to the domestication of cats (F. s. catus) in Asia. Here, we sampled 270 domestic and wild cats across China, sequenced 51 nuclear genomes, 55 mitogenomes, and multi-locus regions from modern and museum specimens. Genome-wide phylogenies supported taxonomic classification of the Chinese mountain cat as wildcat subspecies, F. s. bieti. No involvement of F. s. bieti in cat domestication in East Asia was detected, confirming that domestic cats shared a single origin from the African wildcat (F. s. lybica). A complex hybridization scenario including ancient introgression from the Asiatic wildcat (F. s. ornata) to F. s. bieti, and contemporary gene flow between F. s. bieti and sympatric domestic cats in the Tibetan region, raises the prospect of disrupting the genetic integrity of F. s. bieti, an issue with profound conservation implications.

evolutionary biology↗

bioRxiv2020

Localization, proteomics and metabolite profiling reveal a putative vesicular transporter for UDP-glucose

Vesicular neurotransmitter transporters (VNTs) mediate the selective uptake and enrichment of small molecule neurotransmitters into synaptic vesicles (SVs) and are therefore a major determinant of the synaptic output of specific neurons. To identify novel VNTs expressed on SVs (thus identifying new neurotransmitters and/or neuromodulators), we conducted localization profiling of 361 solute carrier (SLC) transporters tagging with a fluorescent protein in neurons, which revealed 40 possible candidates through comparison with a known SV marker. We parallelly performed proteomics analysis of immunoisolated SVs and identified 7 transporters in overlap. Ultrastructural analysis confirmed one of the transporters, SLC35D3, localized to SVs. Finally, by combining metabolite profiling with a radiolabeled substrate transport assay, we identified UDP-glucose as the principal substrate for SLC35D3. These results provide new insights into the functional role of SLC transporters in neurotransmission and improve our understanding of the molecular diversity of chemical transmitters.

neuroscience↗