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Baerenfaller, K.

Publications and source records attributed to Baerenfaller, K..

3 recordsLinked to original sources

L-Phenylalanine is a metabolic checkpoint of human Th2 cells

After the primary response, circulating memory CD4+T effector and T regulatory cells (Treg) regulate recall responses, which are impaired in allergy. Using mass spectrometry, we discovered distinct metabolomes of these cells in humans and their unique enrichment in amino acids. By assessing energy metabolism in in vitro and ex vivo single-cell analyses, we determined that increased intracellular L-phenylalanine boosts glycolysis while limiting OXPHOS in CD4+T, memory CD4+T and Th2, but not in Treg cells. L-phenylalanine also restrains memory CD4+T proliferation in an IL4I1-dependent manner and inhibits Th2 cell proliferation and differentiation. RNA-sequencing, metabolomics, flow cytometry and proteomics, validated in vitro and across patients cohorts, revealed an impairment in LAT1-dependent transport of L-phenylalanine into Th2 cells in allergy with an increase in its intracellular processing, accompanied by an expansion of pathogenic Th2 cells. Thus, our study identifies L-phenylalanine as a checkpoint in the development, energy metabolism and function of Th2 cells.

immunology↗

GeneSelectR: An R Package Workflow for Enhanced Feature Selection from RNA Sequencing Data

MotivationHigh-dimensional Bulk RNA sequencing (RNAseq) datasets pose a considerable challenge in identifying biologically relevant features for downstream analyses and data mining efforts. The standard approach involves differential gene expression (DGE) analysis, but its effectiveness can be limited depending on the data due to its univariate nature. In complex datasets, an alternative approach involves employing a variety of machine learning (ML) tools, which attempt to understand non-linear relationships between features and focus on generalizability rather than statistical significance. This approach will result in the generation of multiple feature lists, which might exhibit similarities in terms of classification performance metrics. Therefore, there is an urgent need for a cohesive workflow that seamlessly integrates robust feature selection using diverse ML methods while also evaluating the biological relevance of the resulting feature lists. This combined approach would enable the prioritization of the best-performing list, considering both sets of criteria. ResultsWe introduce GeneSelectR, an open-source R package that innovatively combines ML and bioinformatic data mining approaches for enhanced feature selection. With GeneSelectR, features can be selected from a normalized RNAseq dataset with a variety of ML methods and user-defined parameters. This is followed by an assessment of their biological relevance with Gene Ontology (GO) enrichment analysis, along with a semantic similarity analysis of the resulting GO terms. Additionally, similarity coefficients and fractions of the GO terms of interest are calculated. With this, GeneSelectR optimizes ML performance and rigorously assesses the biological relevance of the various lists, offering a means to prioritize feature lists with regard to the biological question. When applied to the TCGA-BRCA dataset, the GeneSelectR workflow generated several feature lists using different ML methods and a DGE analysis. By leveraging the various functions in GeneSelectR, the different lists could be evaluated based on both ML performance and biological relevance. This comprehensive evaluation facilitated the selection of the best-performing list, which exhibited both strong machine learning performance and high relevance to the biological question while maintaining a manageable number of highly specific features. AvailabilityThe package is available on CRAN. To install it, run: install.packages( GeneSelectR) Contactdzhakparov@gmail.com Supplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

Photoperiodic control of the Arabidopsis proteome reveals a translational coincidence mechanism

Plants respond to seasonal cues, such as the photoperiod, to adapt to current conditions and to prepare for environmental changes in the season to come. To assess photoperiodic responses at the protein level, we quantified the proteome of the model plant Arabidopsis thaliana by mass spectrometry across four photoperiods. This revealed coordinated changes of abundance in proteins of photosynthesis, primary and secondary metabolism, including pigment biosynthesis, consistent with higher metabolic activity in long photoperiods. Higher translation rates in the daytime than the night likely contribute to these changes via rhythmic changes in RNA abundance. Photoperiodic control of protein levels might be greatest only if high translation rates coincide with high transcript levels in some photoperiods. We term this proposed mechanism {acute}translational coincidence{acute}, mathematically model its components, and demonstrate its effect on the Arabidopsis proteome. Datasets from a green alga and a cyanobacterium suggest that translational coincidence contributes to seasonal control of the proteome in many phototrophic organisms. This may explain why many transcripts but not their cognate proteins exhibit diurnal rhythms.

plant biology↗