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Biomedical subjects

Ernesto S Nakayasu

Publications and source records attributed to Ernesto S Nakayasu.

8 recordsLinked to original sources

A benchmarking study of feature screening approaches across type 1 diabetes omics studies classification settings.

In recent years, high dimensional omics analyses have become more commonplace for investigating complex biological systems. Typically, these studies attempt to identify key biomolecules associated with a particular biological process. Often, machine learning (ML) is used to identify these biomolecules, typically by learning which biomolecules are highly predictive of a treatment, biological outcome, or phenotype. A major challenge of applying ML to high throughput omics is overcoming noise when sample size is limited and unbalanced with respect to tens of thousands of biomolecules measured. Thus, feature selection (the process of reducing the number of predictors) is both a critical and common step in the ML analysis pipeline. While much attention has been given to embedding and wrapping techniques for feature selection in the omics space, filter-based methods for model-free feature selection have appealing theoretical properties. This manuscript evaluates sure screening, a class of filter-based feature selection methods which provide analytical guarantees for true feature set retention. Here, we cover existing feature screening methods based on the sure screening principal, available software, methods to improve feature screening, and contextualize feature screening in the larger discussion of feature selection for omics data analysis. Additionally, a suite of model-free sure screening approaches is applied and compared for several omics biomedical applications in a ML classification context. We identified BcorSIS as the most effective and computationally efficient screening method across various omics datasets, consistently outperforming others like CSIS and DCSIS in runtime.

Humans↗

Large-scale discovery platform enables identification of peptides targeting drug-resistant candidiasis.

Natural products have an unparalleled track record as sources of clinical drugs. Among them, nonribosomal peptides (NRPs) stand as one of the most therapeutically significant classes, encompassing numerous approved anti-infective and anticancer agents. Yet, discovering bioactive NRPs remains profoundly challenging due to their complex biosynthesis and chemical architecture. Here, we present NPDiscover, a pathogen-oriented, scalable bioinformatics platform that integrates genome mining, metabolomics, and machine learning to identify NRPs active against drug-resistant pathogens. Applying NPDiscover to Actinobacteria datasets, we discovered edaphochelin A, a previously unreported NRP that kills multi-drug-resistant Candida auris and Candida glabrata by disrupting respiratory chain proteins. Structural elucidation via nuclear magnetic resonance and mass spectrometry, alongside in vitro and in vivo validation, confirmed its efficacy, safety, and a mode of action distinct from existing antifungals-establishing edaphochelin A as a compelling drug candidate and NPDiscover as a powerful engine for scalable natural product discovery.

CP: biotechnology↗

Proteome-Scale Tissue Mapping Using Mass Spectrometry Based on Label-Free and Multiplexed Workflows.

Multiplexed bimolecular profiling of tissue microenvironment, or spatial omics, can provide deep insight into cellular compositions and interactions in healthy and diseased tissues. Proteome-scale tissue mapping, which aims to unbiasedly visualize all the proteins in a whole tissue section or region of interest, has attracted significant interest because it holds great potential to directly reveal diagnostic biomarkers and therapeutic targets. While many approaches are available, however, proteome mapping still exhibits significant technical challenges in both protein coverage and analytical throughput. Since many of these existing challenges are associated with mass spectrometry-based protein identification and quantification, we performed a detailed benchmarking study of three protein quantification methods for spatial proteome mapping, including label-free, TMT-MS2, and TMT-MS3. Our study indicates label-free method provided the deepest coverages of ∼3500 proteins at a spatial resolution of 50 μm and the highest quantification dynamic range, while TMT-MS2 method holds great benefit in mapping throughput at >125 pixels per day. The evaluation also indicates both label-free and TMT-MS2 provides robust protein quantifications in identifying differentially abundant proteins and spatially covariable clusters. In the study of pancreatic islet microenvironment, we demonstrated deep proteome mapping not only enables the identification of protein markers specific to different cell types, but more importantly, it also reveals unknown or hidden protein patterns by spatial coexpression analysis.

Proteome↗

Proteome-scale tissue mapping using mass spectrometry based on label-free and multiplexed workflows.

Multiplexed bimolecular profiling of tissue microenvironment, or spatial omics, can provide deep insight into cellular compositions and interactions in healthy and diseased tissues. Proteome-scale tissue mapping, which aims to unbiasedly visualize all the proteins in a whole tissue section or region of interest, has attracted significant interest because it holds great potential to directly reveal diagnostic biomarkers and therapeutic targets. While many approaches are available, however, proteome mapping still exhibits significant technical challenges in both protein coverage and analytical throughput. Since many of these existing challenges are associated with mass spectrometry-based protein identification and quantification, we performed a detailed benchmarking study of three protein quantification methods for spatial proteome mapping, including label-free, TMT-MS2, and TMT-MS3. Our study indicates label-free method provided the deepest coverages of ~3500 proteins at a spatial resolution of 50 µm and the highest quantification dynamic range, while TMT-MS2 method holds great benefit in mapping throughput at >125 pixels per day. The evaluation also indicates both label-free and TMT-MS2 provide robust protein quantifications in identifying differentially abundant proteins and spatially co-variable clusters. In the study of pancreatic islet microenvironment, we demonstrated deep proteome mapping not only enables the identification of protein markers specific to different cell types, but more importantly, it also reveals unknown or hidden protein patterns by spatial co-expression analysis.

Journal Article↗

Integration of Infant Metabolite, Genetic, and Islet Autoimmunity Signatures to Predict Type 1 Diabetes by Age 6 Years.

CONTEXT: Biomarkers that can accurately predict risk of type 1 diabetes (T1D) in genetically predisposed children can facilitate interventions to delay or prevent the disease. OBJECTIVE: This work aimed to determine if a combination of genetic, immunologic, and metabolic features, measured at infancy, can be used to predict the likelihood that a child will develop T1D by age 6 years. METHODS: Newborns with human leukocyte antigen (HLA) typing were enrolled in the prospective birth cohort of The Environmental Determinants of Diabetes in the Young (TEDDY). TEDDY ascertained children in Finland, Germany, Sweden, and the United States. TEDDY children were either from the general population or from families with T1D with an HLA genotype associated with T1D specific to TEDDY eligibility criteria. From the TEDDY cohort there were 702 children will all data sources measured at ages 3, 6, and 9 months, 11.4% of whom progressed to T1D by age 6 years. The main outcome measure was a diagnosis of T1D as diagnosed by American Diabetes Association criteria. RESULTS: Machine learning-based feature selection yielded classifiers based on disparate demographic, immunologic, genetic, and metabolite features. The accuracy of the model using all available data evaluated by the area under a receiver operating characteristic curve is 0.84. Reducing to only 3- and 9-month measurements did not reduce the area under the curve significantly. Metabolomics had the largest value when evaluating the accuracy at a low false-positive rate. CONCLUSION: The metabolite features identified as important for progression to T1D by age 6 years point to altered sugar metabolism in infancy. Integrating this information with classic risk factors improves prediction of the progression to T1D in early childhood.

Autoantibodies↗

A heme-degradation pathway in a blood-sucking insect.

Hematophagous insects are vectors of diseases that affect hundreds of millions of people worldwide. A common physiological event in the life of these insects is the hydrolysis of host hemoglobin in the digestive tract, leading to a massive release of heme, a known prooxidant molecule. Diverse organisms, from bacteria to plants, express the enzyme heme oxygenase, which catalyzes the oxidative degradation of heme to biliverdin (BV) IX, CO, and iron. Here, we show that the kissing bug Rhodnius prolixus, a vector of Chagas' disease, has a unique heme-degradation pathway wherein heme is first modified by addition of two cysteinylglycine residues before cleavage of the porphyrin ring, followed by trimming of the dipeptides. Furthermore, in contrast to most known heme oxygenases, which generate BV IXalpha, in this insect, the end product of heme detoxification is a dicysteinyl-BV IXgamma. Based on these results, we propose a heme metabolizing pathway that includes the identified intermediates produced during modification and cleavage of the heme porphyrin ring.

Animals↗

Trypanosoma cruzi histone H1 is phosphorylated in a typical cyclin dependent kinase site accordingly to the cell cycle.

Histone H1 of most eukaryotes is phosphorylated during the cell cycle progression and seems to play a role in the regulation of chromatin structure, affecting replication and chromosome condensation. In trypanosomatids, histone H1 lacks the globular domain and is shorter when compared with the histone of other eukaryotes. We have previously shown that in Trypanosoma cruzi, the agent of Chagas' disease, histone H1 is phosphorylated and this increases its dissociation from chromatin. Here, we demonstrate using mass spectrometry analysis that T. cruzi histone H1 is only phosphorylated at the serine 12 in the sequence SPKK, a typical cyclin-dependent kinase site. We also found a correlation between the phosphorylation state of histone H1 and the cell cycle. Hydroxyurea and lactacystin, which, respectively, arrest parasites at the G1/S and G2/M stages of the cell cycle, increased the level of histone H1 phosphorylation. Cyclin-dependent kinase-related enzymes TzCRK3, and less intensely the TzCRK1 were able to phosphorylate histone H1 in vitro. Histone H1 dephosphorylation was prevented by treating the parasites with okadaic acid but not with calyculin A. These findings suggest that T. cruzi histone H1 phosphorylation is promoted by cyclin dependent kinases, present during S through G2 phase of the cell cycle, and its dephosphorylation is promoted by specific phosphatases.

Amino Acid Sequence↗

Structure, cellular distribution, antigenicity, and biological functions of Fonsecaea pedrosoi ceramide monohexosides.

Monohexosylceramides (CMHs, or cerebrosides) have been reported as membrane and cell wall constituents of both pathogenic and nonpathogenic fungi, presenting remarkable differences in their ceramide moiety compared to mammalian CMHs. Current evidence suggests that CMHs are involved in fungal differentiation and growth and contribute to host immune response. Here we describe a structural diversity between cerebrosides obtained from different forms of the human pathogen Fonsecaea pedrosoi. The major CMH species produced by conidial forms displayed the same structure previously demonstrated by our group for mycelia, an N-2'-hydroxyhexadecanoyl-1-beta-d-glucopyranosyl-9-methyl-4,8-sphingadienine. However, the major cerebroside species purified from sclerotic cells carries an additional hydroxyl group, bound to its long-chain base. The structural difference between cerebrosides from mycelial and sclerotic cells was apparently not relevant for their antigenicity, since they were both recognized at similar levels by sera from individuals with chromoblastomycosis and a monoclonal antibody to a conserved cerebroside structure. Preincubation of fungal cells with anti-CMH monoclonal antibodies had no effect on the interaction of F. pedrosoi sclerotic cells with murine macrophages. In contrast to what has been described for other fungal species, sclerotic bodies are resistant to the antifungal action of anti-CMH antibodies. Immunofluorescence analysis showed that recognition of sclerotic cells by these antibodies only occurs at cell wall regions in which melanization is not evident. Accordingly, melanin removal with alkali results in an increased reaction of fungal cells with anti-CMH antibodies. Our results indicate that cerebroside expression in F. pedrosoi cells is associated with dimorphism and melanin assembly on the fungal cell wall.

Animals↗