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Mohammed, Y.

Publications and source records attributed to Mohammed, Y..

10 recordsLinked to original sources

CPMsi: a data-driven Computational Pipeline for fast, large-scale Mass Spectrometry Imaging analysis

Mass Spectrometry Imaging (MSI) is increasingly used in clinical research to characterize tissue heterogeneity and identify disease-associated molecular patterns while preserving spatial context. However, translating MSI to large patient cohort studies remains challenging because, among others, existing computational tools struggle to scale with the size and complexity of such datasets. To overcome this bottleneck, we developed CPMsi, a scalable, data-driven computational pipeline for cohort-scale MSI analysis. CPMsi directly processes raw MSI data, performs global spectral alignment using a novel binning strategy, identifies regions of molecular similarity, and generates consensus spectra that compactly capture spatial molecular heterogeneity. The pipeline supports mapping of regions across consecutive tissue sections, and integration of multi-modal and multi-omics MSI acquisitions from the same section. We tested CPMsi using (i) consecutive brain MSI sections comprising ~600,000 and ~500,000 pixels with ~20,000 m/z features, (ii) multimodal brain MSI lipidomic acquired from the same tissue section in positive and negative ionization modes, and (iii) a multi-omics brain MSI dataset of lipidomic, metabolomic, and glycomic measurements. CPMsi identified regions of molecular similarity 30-times faster than vendor-provided MSI analysis software. Consensus spectra substantially reduced data complexity while preserving molecular differences between tissue regions and enabled mapping regions of similar molecular composition across consecutive tissue sections. Integration of complementary MSI modalities further revealed molecular patterns that were not resolved by individual modalities alone. Overall, CPMsi enables efficient reduction, comparison, and integration of complex MSI datasets, providing a scalable framework for cohort-scale studies, biomarker discovery, and future clinical applications.

bioinformatics↗

SysQuan: repurposing SILAC mice for the affordable absolute quantitation of the human proteome

Relative quantitation, used by most MS-based proteomics laboratories to determine protein fold-changes, requires samples being processed and analyzed together for best comparability through minimizing batch differences. This limits the adoption of MS-based proteomics in population-wide studies, and the detection of subtle but relevant changes in heterogeneous samples. Absolute quantitation circumvents these limitations and enables comparison of results across laboratories, studies, and longitudinally. However, high costs of the essential stable isotope labeled (SIL) standards prevents widespread access and limits the number of quantifiable proteins. Our new approach, called "SysQuan", repurposes SILAC mouse tissues/biofluids as system-wide internal standards for matched human samples to enable absolute quantitation of, theoretically, two-thirds of the human proteome using 157,086 shared tryptic peptides. We demonstrate that SysQuan enables quantification of 70% and 31% of the liver and plasma proteomes, respectively. We demonstrate for 14 metabolic proteins that abundant SIL mouse tissues enable cost-effective reverse absolute quantitation in, theoretically, 1000s of human samples. Moreover, 10,000s of light/heavy doublets in untargeted SysQuan datasets enable unique post-acquisition absolute quantitation. SysQuan empowers researchers to replace relative quantitation with affordable absolute quantitation at scale, making data comparable across laboratories, diseases and tissues, enabling completely novel study designs and increasing reusability of data in repositories. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/622109v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@c7a58org.highwire.dtl.DTLVardef@1344320org.highwire.dtl.DTLVardef@2321e3org.highwire.dtl.DTLVardef@85bf2d_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

iSODA: A Comprehensive Tool for Integrative Omics Data Analysis in Single- and Multi-Omics Experiments

Omics technologies including genomics, proteomics, metabolomics, and lipidomics allow profound insights into health and disease. Thanks to plummeting costs of continuously evolving omics analytical platforms, research centers collect multi-omics data more routinely. They are, however, confronted with the lack of a versatile software solution to harmoniously analyze single-omics data and merge and interpret multi-omics data. We have developed iSODA, an interactive web-based application for the analysis of single-as well as multi-omics omics data. The software tool emphasizes intuitive, interactive visualizations designed for user-driven data exploration. Researchers can filter and normalize their datasets and access a variety of functions ranging from simple data visualization like volcano plots and PCA, to advanced functional analyses like enrichment analysis for proteomics and saturation analysis for lipidomics. For insights from integrated multi-omics, iSODA incorporates Multi-Omics Factor Analysis - MOFA, and Similarity Network Fusion - SNF. All results are presented in interactive plots with the possibility of downloading plots and associated data. The ability to adapt the imported data on-the-fly allows for tasks such as removal of outlier samples or failed features, various imputation strategies, or data normalization. The modular design allows for extensions with new analyses and plots. The software is accessible under http://isoda.online/. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/605811v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@1eb61c8org.highwire.dtl.DTLVardef@60a7feorg.highwire.dtl.DTLVardef@1b54b41org.highwire.dtl.DTLVardef@15fd1b2_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical summary for iSODA showcasing some application examples, the data import, the single-omics and multi-omics modules.

bioinformatics↗

The Neurolipid Atlas: a lipidomics resource for neurodegenerative diseases uncovers cholesterol as a regulator of astrocyte reactivity impaired by ApoE4

Lipid changes in the brain have been implicated in many neurodegenerative diseases including Alzheimers Disease (AD), Parkinsons disease and Amyotrophic Lateral Sclerosis. To facilitate comparative lipidomic research across brain-diseases we established a data commons named the Neurolipid Atlas, that we have pre-populated with novel human, mouse and isogenic induced pluripotent stem cell (iPSC)-derived lipidomics data for different brain diseases. We show that iPSC-derived neurons, microglia and astrocytes display distinct lipid profiles that recapitulate in vivo lipotypes. Leveraging multiple datasets, we show that the AD risk gene ApoE4 drives cholesterol ester (CE) accumulation in human astrocytes recapitulating CE accumulation measured in the human AD brain. Multi-omic interrogation of iPSC-derived astrocytes revealed that cholesterol plays a major role in astrocyte interferon-dependent pathways such as the immunoproteasome and major histocompatibility complex (MHC) class I antigen presentation. We show that through enhanced cholesterol esterification ApoE4 suppresses immune activation of astrocytes. Our novel data commons, available at neurolipidatlas.com, provides a user-friendly tool and knowledge base for a better understanding of lipid dyshomeostasis in neurodegenerative diseases.

neuroscience↗

Neuronal polyunsaturated fatty acids are protective in FTD/ALS

We report a conserved transcriptomic signature of reduced fatty acid and lipid metabolism gene expression in human post-mortem ALS spinal cord and a Drosophila model of the most common genetic cause of FTD/ALS, a repeat expansion in C9orf72. To investigate lipid alterations, we performed lipidomics on C9FTD/ALS iPSC-neurons and post-mortem FTLD brain tissue. This revealed a common and specific reduction in phospholipid species containing polyunsaturated fatty acids (PUFAs). To determine whether this PUFA deficit contributes to neurodegeneration, we fed C9FTD/ALS flies PUFAs, which yielded a modest increase in survival. However, increasing PUFA levels specifically in neurons of the C9orf72 flies, by overexpressing fatty acid desaturase enzymes, led to a substantial extension of lifespan. Neuronal overexpression of fatty acid desaturases also suppressed stressor induced neuronal death in C9FTD/ALS patient iPSC-neurons. These data implicate neuronal fatty acid saturation in the pathogenesis of FTD/ALS and suggest that interventions to increase PUFA levels specifically within neurons will be beneficial.

neuroscience↗

Fatty acid desaturation and lipoxygenase pathways support trained immunity

Infections and vaccinations can induce long-term enhanced responses of innate immune cells to heterologous stimuli, establishing a de facto innate immunological memory termed trained immunity. Monocytes exposed to the Bacillus Calmette-Guerin (BCG) vaccine, have a trained immunity phenotype, characterized by an increased biosynthesis of different lipid mediators (LMs) derived from long-chain polyunsaturated fatty acids (PUFAs). Pharmacological and genetic approaches showed that long-chain PUFA synthesis and lipoxygenase (LOX)-derived LMs are crucial for the BCG trained immunity responses of human monocytes. Furthermore, monocytes of healthy individuals vaccinated with BCG are enriched in 12-LOX products. The elucidation of the lipid metabolic pathways that promote innate immune memory contributes to our understanding of trained immunity and may help identify therapeutic tools and targets for the modulation of innate immune responses.

immunology↗

The establishment and transmission of novel foraging techniques indicates a capacity for culture in bumblebees (Bombus terrestris).

The astonishing behavioural repertoires of social insects have been thought largely innate, but these insects have repeatedly demonstrated remarkable capacities for both individual and social learning. Using the bumblebee Bombus terrestris as a model, we developed a two-option puzzle box task and used open diffusion paradigms to observe the transmission of novel, non-natural foraging behaviours through populations. Box-opening behaviour spread through colonies seeded with a demonstrator trained to perform one of the two possible behavioural variants, and the observers acquired the demonstrated variant. This preference persisted among observers even when the alternative technique was discovered. In control diffusion experiments that lacked a demonstrator, some bees spontaneously opened the puzzle boxes but were significantly less proficient than those that learned in the presence of a demonstrator. This suggested that social learning was crucial to proper acquisition of box-opening. Additional open diffusion experiments where two behavioural variants were initially present in similar proportions ended with a single variant becoming dominant, due to stochastic processes. This could lead to the emergence and maintenance of local cultural variation. These results suggest that bumblebees, like mammals and birds, may have the capacity for culture and to sustain cultural variation.

animal behavior and cognition↗

Clostridioides difficile phosphoproteomics shows an expansion of phosphorylated proteins in stationary growth phase

Phosphorylation is a post-translational modification that can affect both house-keeping functions and virulence characteristics in bacterial pathogens. In the Gram-positive enteropathogen Clostridioides difficile the extent and nature of phosphorylation events is poorly characterized, though a protein-kinase mutant strain demonstrates pleiotropic phenotypes. Here, we used an immobilized metal affinity chromatography strategy to characterize serine, threonine and tyrosine phosphorylation in C. difficile. We find limited protein phosphorylation in the exponential growth phase but a sharp increase in the number of phosphopeptides after the onset of stationary growth phase. Among the overall more than 1500 phosphosites, our approach identifies expected targets and phosphorylation sites, including the protein kinase PrkC, the anti-sigma-F factor antagonist (SpoIIAA), the anti-sigma-B factor antagonist (RsbV) and HPr kinase/phosphorylase (HprK). Analysis of high-confidence phosphosites shows that phosphorylation on serine residues is most common, followed by threonine and tyrosine phosphorylation. This work forms the basis for a further investigation into the contributions of individual kinases to the overall phosphoproteome of C. difficile and the role of phosphorylation in C. difficile physiology and pathogenesis. ImportanceIn this manuscript, we present a comprehensive analysis of protein phosphorylation in the Gram-positive enteropathogen Clostridioides difficile. To date, only limited evidence on the role of phosphorylation in regulation in this organism has been published; the current study is expected to form the basis for research on this post-translational modification in C. difficile.

microbiology↗

Site-specific glycosylation mapping of Fc gamma receptor IIIb from neutrophils of health donors

Fc gamma receptors (Fc{gamma}R) translate antigen-recognition by immunoglobulin G (IgG) into various immune responses. A better understanding of this key element of immunity promises novel insights into mechanisms of (auto-/allo-)immune diseases and more rationally designed antibody-based drugs. Glycosylation on both IgG and Fc{gamma}R impacts their interaction dramatically. In this study, we developed a straightforward and comprehensive analytical methodology to map Fc{gamma}RIIIb glycosylation from primary human material. In contrast to recently published alternatives, we assessed all glycosylation sites in a single LC-MS/MS run and simultaneously determined the donor allotype. Studying Fc{gamma}RIIIb derived from healthy donor neutrophils, we observed profound differences as compared to the soluble variant and the homologous Fc{gamma}RIIIa on natural killer cells. This method will allow assessment of Fc{gamma}RIII glycosylation differences between individuals, cell types, subcellular locations and pathophysiological conditions.

immunology↗

Social foraging extends associative odor-food memory expression in fruit flies (Drosophila melanogaster)

Animals socially interact during foraging and share information about the quality and location of food sources. The mechanisms of social information transfer during foraging have been mostly studied at the behavioral level, and its underlying neural mechanisms are largely unknown. The fruit fly Drosophila melanogaster has become a model for studying the neural bases of social information transfer, as fruit flies show a rich repertoire of social behaviors and provide a well-developed genetic toolbox to monitor and manipulate neuronal activity. Social information transfer has already been characterized for fruit flies egg laying, mate choice, foraging and aversive associative learning, however the role of social information transfer on associative odor-food learning during foraging are unknown. Here we present an automated learning and memory assay for walking flies that allows studying the effect of group size on social interactions and on the formation and expression of associative odor-food memories. We found that both inter-fly attraction and the duration of odor-food memory expression increase with group size. We discuss possible behavioral and neural mechanisms of this social effect on odor-food memory expression. This study opens up opportunities to investigate how social interactions are relayed in the neural circuitry of learning and memory expression.

neuroscience↗