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Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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Structured Joint Decomposition (SJD) identifies conserved molecular dynamics across collections of biologically related multi-omics data matrices

It is necessary to develop exploratory tools to learn from the unprecedented volume of high-dimensional multi-omic data currently being produced across the field of biomedicine. We have developed an R package, Structured Joint Decomposition (SJD), which identifies components of variation that are shared across multiple matrices. The approach focuses specifically on variation across the samples/cells within each dataset while incorporating biologist-defined hierarchical structure among input experiments that can span in vivo and in vitro systems, multi-omic data modalities, and species. SJD enables the definition of molecular variation that is conserved across systems, those that are shared within subsets of studies, and elements unique to individual matrices. We have included functions to simplify the construction and visualization of highly complex in silico experiments involving many diverse multi-omic matrices from multiple species. Here we apply SJD to decompose four RNA-seq experiments focused on neurogenesis in the neocortex. The public datasets used in this analysis are at NeMO Analytics and can be explored at the individual gene level or using the conserved transcriptomic dynamics in mammalian neurogenesis that we define here. The SJD R package and tutorial can be found at https://chuansite.github.io/SJD. Contact: hzchenhuan@gmail.com; ccolant1@jhmi.edu [carlocolantuoni.org]

bioinformatics↗

Peptide Information Compression Technology (PICT): A New Frontier in Therapeutic Peptide Discovery

Therapeutic peptides hold tremendous market potential, yet the discovery methods for active peptides lag considerably behind those for small molecules and biological macromolecule drugs. Due to their respective limitations, traditional peptide compound synthesis and display libraries fail to meet the growing demands of the peptide drug market. Here, we introduce a novel Peptide Information Compression Technology (PICT) and, based on this technology, a large-scale physical peptide library and its accompanying high-throughput screening (HTS) platform. By screening for inhibitors of TSLP/TSLPR/IL7R and antagonists of MC3R at both the molecular and cellular levels, we have identified active molecules in the single-digital micromolar and nanomolar ranges, respectively. This demonstrates the immense application value of Peptide Information Compression Technology in the efficient discovery of peptide drugs.

molecular biology↗

SpeciesRax: A tool for maximum likelihood species tree inference from gene family trees under duplication, transfer, and loss.

Species tree inference from gene family trees is becoming increasingly popular because it can account for discordance between the species tree and the corresponding gene family trees. In particular, methods that can account for multiple-copy gene families exhibit potential to leverage paralogy as informative signal. At present, there does not exist any widely adopted inference method for this purpose. Here, we present SpeciesRax, the first maximum likelihood method that can infer a rooted species tree from a set of gene family trees and can account for gene duplication, loss, and transfer events. By explicitly modelling events by which gene trees can depart from the species tree, SpeciesRax leverages the phylogenetic rooting signal in gene trees. SpeciesRax infers species tree branch lengths in units of expected substitutions per site and branch support values via paralogy-aware quartets extracted from the gene family trees. Using both empirical and simulated datasets we show that SpeciesRax is at least as accurate as the best competing methods while being one order of magnitude faster on large datasets at the same time. We used SpeciesRax to infer a biologically plausible rooted phylogeny of the vertebrates comprising 188 species from 31612 gene families in one hour using 40 cores. SpeciesRax is available under GNU GPL at https://github.com/BenoitMorel/GeneRax and on BioConda.

molecular biology↗

A novel chimeric RNA originating from BmCPV S4 and Bombyx mori HDAC11 transcripts regulates virus proliferation

Polymerases encoded by segmented negative-strand RNA viruses cleave 5-m7G-capped host transcripts to prime viral mRNA synthesis ( cap-snatching) to generate chimeric RNA, and trans-splicing occurs between viral and cellular transcripts. Bombyx mori cytoplasmic polyhedrosis virus (BmCPV), an RNA virus belonging to Reoviridae, is a major pathogen of silkworm (B. mori). The genome of BmCPV consists of 10 segmented double-stranded RNAs (S1-S10) from which viral RNAs encoding a protein are transcribed. In this study, chimeric silkworm-BmCPV RNAs, in which the sequence derived from the silkworm transcript could fuse with both the 5 end and the 3 end of viral RNA, were identified in the midgut of BmCPV-infected silkworms by RNA_seq and further confirmed by PCR and Sanger sequencing. A novel chimeric RNA, HDAC11-S4 RNA 4, derived from silkworm histone deacetylase 11 (HDAC11) and the BmCPV S4 transcript encoding viral structural protein 4 (VP4), was selected for validation by in situ hybridization and Northern blotting. Interestingly, our results indicated that HDAC11-S4 RNA 4 was generated in a BmCPV RNA-dependent RNA polymerase (RdRp)-independent manner and could be translated into a truncated BmCPV VP4 with a silkworm HDAC11-derived N-terminal extension. Moreover, it was confirmed that HDAC11-S4 RNA 4 inhibited BmCPV proliferation, decreased the level of H3K9me3 and increased the level of H3K9ac. These results indicated that during infection with BmCPV, a novel mechanism, different from that described in previous reports, allows the genesis of chimeric silkworm-BmCPV RNAs with biological functions. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/527451v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1b3b949org.highwire.dtl.DTLVardef@4972c0org.highwire.dtl.DTLVardef@cc15aorg.highwire.dtl.DTLVardef@16a0a19_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

Aggressive high-grade NF2 mutant meningiomas downregulate oncogenic YAP signaling via the upregulation of VGLL4 and FAT3/4.

Meningiomas are the most common primary brain tumors in adults. Although generally benign, a subset of meningiomas is of higher grade, shows aggressive growth behavior and recurs even after multiple surgeries. Around half of all meningiomas harbor inactivating mutations in NF2. While benign low-grade NF2 mutant meningiomas exhibit few genetic events in addition to NF2 inactivation, aggressive high-grade NF2 mutant meningiomas frequently harbor a highly aberrant genome. We and others have previously shown that NF2 inactivation leads to YAP1 activation and that YAP1 acts as the pivotal oncogenic driver in benign NF2 mutant meningiomas. Using bulk and single-cell RNA-Seq data from a large cohort of human meningiomas, we show that aggressive NF2 mutant meningiomas harbor decreased levels YAP1 activity compared to their benign counterparts. Decreased expression levels of YAP target genes are significantly associated with an increased risk of recurrence. We then identify the increased expression of the YAP1 competitor VGLL4 as well as the YAP1 upstream regulators FAT3/4 as a potential mechanism for the downregulation of YAP activity in aggressive NF2 mutant meningiomas. High expression of these genes is significantly associated with an increased risk of recurrence. In vitro, overexpression of VGLL4 resulted in the downregulation of YAP activity in benign NF2 mutant meningioma cells, confirming the direct link between VGLL4 expression and decreased levels of YAP activity observed in aggressive NF2 mutant meningiomas. Our results shed new insight on the biology of benign and aggressive NF2 mutant meningiomas and may have important implications for the efficacy of therapies targeting oncogenic YAP1 activity in NF2 mutant meningiomas.

molecular biology↗

Non-invasive characterization of human bone marrow by cell free messenger-RNA reveals response to growth factor stimulation and hematopoietic reconstitution after transplantation

Circulating cell free mRNA (cf-mRNA) holds great promise as a non-invasive diagnostic biomarker. However, the biological origin of cf-mRNA is still not well understood, limiting the clinical applications of this technology. Here, we use the bone marrow (BM) and pharmacologic manipulation of its resident cells as a window to study the origin of cf-mRNA. Using NGS-based profiling, we show that cf-mRNA is enriched in transcripts derived from the BM compared to circulating cells. Further, BM ablation experiments followed by hematopoietic stem cell transplants in cancer patients show that cf-mRNA levels reflect the transcriptional activity of BM resident hematopoietic lineages during marrow reconstitution. Finally, by stimulating specific BM cell populations in vivo using growth factor therapeutics (i.e. EPO, G-CSF), we show that cf-mRNA reveals dynamic functional changes in growing cell types, suggesting that, unlike other cell-free nucleic acids, cf-mRNA is secreted from living cells, rather than exclusively from apoptotic cells. Our results shed new light on the biology of cf-mRNA and demonstrate its potential applications in clinical practice.

molecular biology↗

Template switching by a group II intron reverse transcriptase: biochemical analysis and implications for RNA-seq

The reverse transcriptases (RTs) encoded by mobile group II intron and other non-LTR-retro-elements differ from retroviral RTs in being able to template switch from the 5 end of one template to the 3 end of another without pre-existing complementarity between the donor and acceptor nucleic acids. Here, we used the ability of a thermostable group II intron RT (TGIRT; GsI-IIC RT) to template switch directly from synthetic RNA template/DNA primer duplexes having either a blunt end or a 3-DNA overhang end to establish a complete kinetic framework for the reaction and identify conditions that more efficiently capture acceptor RNAs or DNAs. The rate and amplitude of template switching are optimal from starter duplexes with a single nucleotide 3-DNA overhang complementary to the 3 nucleotide of the acceptor RNA, suggesting a role for non-templated nucleotide addition of a complementary nucleotide to the 3 end of cDNAs synthesized from natural templates. Longer 3-DNA overhangs progressively decrease the rate of template switching, even when complementary to the 3 end of the acceptor template. The reliance on a single base pair with the 3 nucleotide of the acceptor together with discrimination against mismatches and the high processivity of the enzyme enable synthesis of full-length DNA copies of nucleic acids beginning directly at their 3 end. We discuss possible biological functions of the template-switching activity of group II intron and other non-LTR-retroelements RTs, as well as the optimization of this activity for adapter addition in RNA-and DNA-seq.

molecular biology↗

Proteomics Characteristics Reveal the Risk of T1 Colorectal Cancer Metastasis to Lymph Nodes

BackgroundThe presence of lymph node metastasis (LNM) affects treatment strategy decisions in T1NxM0 colorectal cancer (CRC), but the currently used clinicopathological-based risk stratification cannot predict LNM accurately. In this study, we established a classifier for predicting LNM in T1 CRC. MethodsWe detected proteins in formalin-fixed paraffin-embedded (FFPE) tumor samples from 143 LNM-negative and 78 LNM-positive patients with T1 CRC and revealed changes in molecular and biological pathways by label-free LC-MS/MS. An effective prediction model was built and validated in a training cohort (N=132) and two validation cohorts (VC1, N=42; VC2, N=47) by machine learning. We further built a simplified classifier with 9 proteins. The expression patterns of 13 proteins were confirmed by immunohistochemistry, and the IHC score of 5 proteins were used to build a IHC predict model. ResultPatients with or without LNM have different molecular signatures. The 55-proteins prediction model achieved an impressive AUC of 1.00 in the training cohort, 0.96 in VC1 and 0.93 in VC2. The 9-protein classifier achieved an AUC of 0.824, and the calibration plot was excellent. We found that 5 biomarkers could predict LNM by the IHC score, with an AUC of 0.825. RHOT2 silence significantly enhanced migration and invasion of colon cancer cells. ConclusionsOur study explored the mechanism of metastasis in T1 CRC and can be used to facilitate the individualized prediction of LNM in patients with T1 CRC, which may provide a guidance for clinical practice in T1 CRC.

cancer biology↗

LotOfCells: data visualization and statistics of single cell metadata

Single-cell sequencing unveils a treasure trove into the biological and molecular characteristics of samples. Yet, within this flood of data, the challenge to draw meaningful conclusions sometimes can be time consuming and a tortuous process. Here we introduce LotOfCells: a simple R package designed to explore the intricate landscape of phenotypic data within single-cell studies. Normally, we are interested in visualizing and measuring if the differences in the proportion of number of cells across various covariates is significant or biologically relevant. As an example, one of the most common questions is the proportion of different cell types across conditions in our experiment, or the cluster composition before and after treatment (e.g.: difference in cell type proportions between wild type and mutant). LotOfCells helps with the interpretation and visualization of meta-data of these recurrent scenarios, including the test of proportion changes across multiple ordered stages. Additionally, it computes a symmetric divergence score to measure global deregulation of cell proportions due to a condition. Code repositoryR package, manual and relevant examples can be accessed on the GitHub repository: https://github.com/OscarGVelasco/LotOfCells

bioinformatics↗

Identification of specific biomarkers and pathways in the synovial tissues of patients with osteoarthritis in comparison to rheumatoid arthritis

Osteoarthritis and rheumatoid arthritis are two common arthritis with different pathogenesis. Here, we explore the difference of genes and biological pathways in human synovial fibroblasts by using a bioinformatics method to clarify their potential pathogenesis. The GSE7669 dataset was originally produced by using an Affymetrix Human Genome U95 platform. We used the KEGG and GO analysis to identify the functional categories and pathways. Our results suggested that biological adhesion and cell adhesion are the main signaling pathways in osteoarthritis in comparison to rheumatoid arthritis. Furthermore, Albumin, MAPK3, PTPRC, COL1A1, and CXCL12 may be key genes in osteoarthritis. Therefore, our study provides potential targets for the specific and accurate therapy of osteoarthritis.

molecular biology↗

Inhibited KdpFABC resides in an E1 off-cycle state

KdpFABC is a high-affinity prokaryotic K+ uptake system that forms a functional chimera between a channel-like subunit (KdpA) and a P-type ATPase (KdpB). At high K+ levels, KdpFABC needs to be inhibited to prevent excessive K+ accumulation to the point of toxicity. This is achieved by a phosphorylation of the serine residue in the TGES162 motif in the A domain of the pump subunit KdpB (KdpBS162-P). Here, we explore the structural basis of inhibition by KdpBS162 phosphorylation by determining the conformational landscape of KdpFABC under inhibiting and non-inhibiting conditions. Under turnover conditions, we identified a new inhibited KdpFABC conformation that we termed E1-P tight, which is not part of the canonical Post-Albers transport cycle of P-type ATPases. It likely represents the biochemically described stalled E1-P state adopted by KdpFABC upon KdpBS162 phosphorylation. The E1-P tight state exhibits a compact fold of the three cytoplasmic domains and is likely adopted when the transition from high-energy E1-P states to E2-P states is unsuccessful. This study represents a structural characterization of a biologically relevant off-cycle state in the P-type ATPase family and supports the emerging discussion of P-type ATPase regulation by such conformations.

molecular biology↗

A palmitoyl transferase chemical genetic system to map ZDHHC-specific S-acylation

The 23 human ZDHHC S-acyltransferases catalyze long-chain S-acylation at cysteine residues across an extensive network of hundreds of proteins important for normal physiology or dysregulated in disease. Here we present a technology platform to directly map the protein substrates of a specific ZDHHC for the first time at the whole proteome level, in intact cells. Structure-guided engineering of paired ZDHHC hole mutants and bumped chemically tagged fatty acid probes enabled probe transfer to specific protein substrates with excellent selectivity over wild type ZDHHCs. Chemical genetic systems were exemplified for five ZDHHCs (3, 7, 11, 15 and 20), and applied to generate the first de novo ZDHHC substrate profiles, identifying >300 unique and shared substrates across multiple cell lines and S-acylation sites for novel functionally diverse substrates. We expect that this powerful and versatile platform will open a new window on S-acylation biology for a wide range of models and organisms.

molecular biology↗

Effective lowering of α-synuclein expression by targeting G-quadruplex structures within the SNCA genome

Alpha-synuclein, encoded by the SNCA gene, is a pivotal protein implicated in the pathogenesis of synucleinopathies, including Parkinsons disease. Current approaches for modulating alpha-synuclein levels involve antisense nucleotides, siRNAs, and small molecules targeting SNCAs 5-UTR mRNA. Here, we propose a groundbreaking strategy targeting G-quadruplex structures to effectively modulate SNCA gene expression and lowering alpha-synuclein amount. Novel G-quadruplex sequences, identified on the SNCA genes transcription starting site and 5-UTR of SNCA mRNAs, were experimentally confirmed for their stability through biophysical assays and in vitro experiments on human genomic DNA. Biological validation in differentiated SH-SY5Y cells revealed that well-known G-quadruplex ligands remarkably stabilized these structures, inducing the modulation of SNCA mRNAs expression, and the effective decrease in alpha-synuclein amount. Besides, a novel peptide nucleic acid conjugate, designed to selectively disrupt of G-quadruplex within the SNCA gene promoter, caused a promising lowering of both SNCA mRNA and alpha-synuclein protein. Altogether our findings highlight G-quadruplexes key role as intriguing biological targets in achieving a notable and successful reduction in alpha-synuclein expression, pointing to a novel approach against synucleinopathies.

molecular biology↗

Multisite Assembly of Gateway Induced Clones (MAGIC): a flexible cloning toolbox withdiverse applications in vertebrate model systems.

Here we present the Multisite Assembly of Gateway Induced Clones (MAGIC) system, which harnesses site-specific recombination-based cloning via Gateway technology for rapid, modular assembly of between 1 and 3 "Entry" vector components, all into a fourth, standard high copy "Destination" plasmid backbone. The MAGIC toolkit spans a range of in vitro and in vivo uses, from directing tunable gene expression, to driving simultaneous expression of microRNAs and fluorescent reporters, to enabling site-specific recombinase-dependent gene expression. All MAGIC system components are directly compatible with existing multisite gateway Tol2 systems currently used in zebrafish, as well as existing eukaryotic cell culture expression Destination plasmids, and available mammalian lentiviral and adenoviral Destination vectors, allowing rapid cross-species experimentation. Moreover, herein we describe novel vectors with flanking piggyBac transposon elements for stable genomic integration in vitro or in vivo when used with piggyBac transposase. Collectively, the MAGIC system facilitates transgenesis in cultured mammalian cells, electroporated mouse and chick embryos, as well as in injected zebrafish embryos, enabling the rapid generation of innovative DNA constructs for biological research due to a shared, common plasmid platform.

molecular biology↗

An integrated DNA interactome and transcriptome profiling reveals a PU.1/enhancer RNA-mediated Feed-forward Regulatory Loop Regulating monocyte/macrophage development and innate immune functions

High expression of the myeloid master ETS transcription factor PU.1 drives the development of monocyte/macrophage (Mono/M{Phi}), a crucial cellular component of the innate immune system. Disruptions in normal expression patterns of PU.1 are linked to a variety myeloid malignancy and immune diseases. It is evidenced that PU.1 binds to and modulates enhancers of several myeloid genes. While noncoding RNAs transcribed from noncoding genes at the enhancers are increasingly reported to be involved in enhancer regulation, the crosstalk between PU.1 and noncoding RNAs in enhancer-mediated myeloid gene regulation in Mono/M{Phi} differentiation and immune response has not been systematically investigated. In this study, we interrogated the PU.1-mediated transcriptome and cistrome with our comprehensive collection of putative and verified enhancers. Among a repertoire of noncoding genes present at PU.1-bound enhancers, we discovered that PU.1 acts as a potent transcription factor inducer of the noncoding RNA LOUP, which we previously identified as an RNA inducer of PU.1. The genomic region within the LOUP locus occupied by PU.1 is characterized by the epigenetic features of a myeloid-specific super-enhancer. Targeted disruption of the PU.1-binding motifs resulted in the downregulation of LOUP promoter activity. Depletion of LOUP reduced the expression of Mono/M{Phi} cell markers as well as the transcriptional program associated with Mono/M{Phi} differentiation Mono/M{Phi} innate defense mechanisms, including phagocytosis, antimicrobial activity, and chemoattractant cytokine production. LOUP induces Mono/M{Phi} phagocytic activities. Collectively, our findings indicate that PU.1 and enhancer RNA LOUP are biomolecular components of an unidentified feed-forward loop that promotes their mutual expression, contributing to Mono/M{Phi} differentiation and innate immune functions. The identification of the PU.1/LOUP regulatory circuit provides valuable insights into the mechanisms underlying cell-type and gene-specific enhancer activity and Mono/M{Phi} biology, as well as significant implications for advancing our understanding of immune diseases and myeloid malignancies.

molecular biology↗

Liver angiocrine myeloid-derived growth factor protects against endothelial dysfunction in pulmonary arterial hypertension

Myeloid-derived growth factor (MYDGF) is a hepatic angiokine with protective effects in systemic vascular beds, but its role in pulmonary arterial hypertension (PAH) is unknown. We hypothesized that hepatic MYDGF deficiency contributes to pulmonary endothelial activation in PAH and that recombinant MYDGF could rescue endothelial injury. In the Sugen-hypoxia (SuHx) rat model, hepatic MYDGF expression was decreased, while pulmonary vascular cell adhesion molecule-1 (VCAM-1) expression was increased. Human hepatic sinusoidal endothelial cells exposed to pro-inflammatory macrophage conditioned media downregulated MYDGF, and recombinant MYDGF restored pulmonary artery endothelial cell resistance to inflammatory activation via MAP4K4-NF{kappa}B signaling. In the Brown University PHiNE PAH cohort (n=41 PAH, n=27 controls), plasma proteomics demonstrated increased MYDGF in PAH patients compared with controls, but MYDGF levels declined with worsening liver stiffness and correlated with higher pulmonary vascular resistance. In the independent Servetus PAH cohort (n=117), higher plasma MYDGF was associated with mortality and right ventricular dilation. Together, these findings demonstrate hepatic MYDGF deficiency in experimental PAH, tissue specificity of endothelial MYDGF to the liver, and MYDGFs potential to mitigate pulmonary endothelial inflammation. However, human data suggest a paradoxical association of elevated circulating MYDGF with adverse outcomes, underscoring the complex biology of angiogenic growth factors in PAH. MYDGF may represent a novel hepatic angiokine linking systemic inflammation, liver dysfunction, and pulmonary vascular disease.

molecular biology↗

Automatic colocalization of high resolution MALDI MSI and Raman imaging applied to cardiac tissue of Fabry disease mouse models

Understanding early molecular changes in biological tissues is crucial for diagnosing pathological and genetic diseases and for elucidating their underlying mechanisms. However, localized molecular alterations of low molecular-weight compounds are not inferred from conventional staining or genetic methods. Here, we established a multimodal imaging approach that integrates Raman spectroscopy and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-MALDI MSI): two complementary, label-free techniques enabling molecular profiling of a broad spectrum of biomolecules from one single tissue section. This method was applied to detect Gb3 accumulation in heart tissue of murine models of Fabry disease, including mice deficient in -galactosidase A (GLA) activity (GLA knock-out) and transgenic mice with a GLA knock-out and an upregulation of globotriaosylceramides (Gb3) synthase. With AP-MALDI MSI we were able to discern the heterogenous expression of Gb3 lipoforms with down to 5 {micro}m pixel size and reveal the significantly increased Gb3 content in mice containing a GLA knock-out combined with human Gb3 synthase overexpression compared to GLA knock-out and wild type samples. By employing Raman microscopy with a pixel size of 2 {micro}m, we were able to contextualize the physiological alterations in cardiac tissue by identifying components associated with nuclei, tissue, collagen, and lipids for the same three genotypes. An automated co-localization algorithm aligned Raman and AP-MALDI-MSI data from the same tissue section with (5.1 {+/-} 1.6) {micro}m precision, enabling overlay at 5 {micro}m and 2 {micro}m resolution. The method resolved heterogeneous Gb3 distributions and distinct lipid species in cardiac mouse tissue.

molecular biology↗

Solving the first novel protein structure by 3D micro-crystal electron diffraction

Micro-crystal electron diffraction (MicroED) has recently shown potential for structural biology. It enables studying biomolecules from micron-sized 3D crystals that are too small to be studied by conventional X-ray crystallography. However, to the best of our knowledge, MicroED has only been applied to re-determine protein structures that had already been solved previously by X-ray diffraction. Here we present the first unknown protein structure - an R2lox enzyme - solved using MicroED. The structure was phased by molecular replacement using a search model of 35% sequence identity. The resulting electrostatic scattering potential map at 3.0 [A] resolution was of sufficient quality to allow accurate model building and refinement. Our results demonstrate that MicroED has the potential to become a widely applicable tool for revealing novel insights into protein structure and function, opening up new opportunities for structural biologists.

molecular biology↗