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Biology subjects

Kahnert, K.

Publications and source records attributed to Kahnert, K..

5 recordsLinked to original sources

Generative machine learning unlocks the first proteome-wide image of human cells

The spatial organization of proteins within cells governs virtually all cellular functions, yet current imaging can simultaneously visualize only tens of proteins, orders of magnitude below the thousands populating a single human cell. Here we present ProtiCelli, a deep generative model that simulates microscopy images for 12,800 human proteins from just three cellular landmark stains. Trained on 1.23 million Human Protein Atlas images, ProtiCelli outperforms existing methods in reconstruction accuracy and textural fidelity, and generalizes to unseen cell types and drug perturbations. Simulated images preserve hierarchical subcellular organization, recapitulate known protein protein interaction landscapes, and resolve compartment-specific functions of moonlighting proteins at single cell resolution. Remarkably, the model infers drug-induced changes in protein expression and localization from cell morphology alone, predicts cell cycle stage without dedicated markers, and enables unsupervised segmentation of subcellular compartments and spatial decomposition of gene sets into functional regions. We leverage ProtiCelli to generate Proteome2Cell, a dataset of 30.7 million simulated images spanning 2,400 virtual cells across 12 human cell lines, enabling hierarchical single-cell models that distinguish conserved from dynamic protein architectures. Integrated into the Human Protein Atlas, Proteome2Cell democratizes exploration of these virtual cells. By computationally bridging the experimental scalability gap, ProtiCelli establishes a foundation for spatial virtual cell modeling.

cell biology↗

SubCell: Vision foundation models for microscopycapture single-cell biology

Cell morphology and subcellular protein organization provide important insights into cellular function and behavior. These cellular features can be studied using large-scale fluorescence microscopy, and machine learning has become a powerful tool to interpret the resulting images for biological insights. Here, we introduce SubCell, a deep learning model for fluorescence microscopy designed to accurately capture cellular morphology, protein localization, cellular forganization, and biological function beyond what humans can readily perceive. SubCell was trained on the proteome-wide image collection from the Human Protein Atlas with a novel proteome-aware learning objective. SubCell outperforms state-of-the-art methods across a variety of tasks relevant to single-cell biology and generalizes to other fluorescence microscopy datasets without any fine-tuning. Additionally, we construct the first proteome-wide hierarchical map of proteome organization that is directly learned from image data. This vision-based multiscale cell map defines cellular subsystems down to protein complex resolution, reveals proteins with similar functions, and distinguishes dynamic and stable behaviors within cellular compartments. Finally, combining SubCell with a protein sequence model enables a rich multimodal approach to capture gene function better than either vision-only or sequence-only models alone. In conclusion, SubCell creates deep, image-driven representations of cellular architecture that are applicable across diverse biological contexts and datasets.

cell biology↗

Repeated cigarette smoke exposure attenuates the proliferation rate of primary human lung fibroblasts in vitro

BackgroundLung fibroblasts are crucial structural cells involved in airway remodelling and tissue maintenance. The study aimed to analyze the effect of cigarette smoke extract (CSE) on primary human lung fibroblasts at various stages of proliferation to assess whether an initial exposure could exert a protective effect against subsequent exposures. MethodsWe examined the effect of CSE on fibroblasts isolated from 15 donors who had undergone lung surgery. Fibroblast cultures were exposed to 2% CSE early (day 5-7), late (day 9-11), or at both time points (double). Cell counts and viability tests were performed every 2 days. Changes in proliferation rates were determined immediately at the end of each 2-day exposure as well as 2 days afterwards, until the end of the experiment with a plateau of proliferation. Differences between exposures were analyzed by comparing proliferation rates by ANOVA with adjusted post-hoc analyses. ResultsEarly-, late- and double-CSE exposed cultures showed lower proliferation rates (p<0.05 each) compared to unexposed cultures. The response to late-CSE exposure varied depending on whether an initial CSE exposure had occurred, suggesting a protective effect from the early exposure. Changes observed over the 2-day exposure period and the subsequent 2 days (a total of 4 days) yielded similar results to those recorded during just the 2-day exposure period. Proliferation rates varied among cells from different donors, but responses correlated across different exposure regimens, indicating inherent differences in susceptibility to CSE. ConclusionsRepeated CSE exposures attenuated the proliferation of primary human lung fibroblasts more strongly than a single exposure, despite the fact that an early CSE exposure appeared to protect against the CSE in repetitively exposed fibroblast cultures. Our results highlight that while significant differences may occur among primary cells from different donors in vitro, responses can remain consistent across various exposure conditions.

cell biology↗

Intrinsic Diversity in Primary Cilia Revealed Through Spatial Proteomics

Primary cilia are a critical organelle found on most human cells, and their dysfunction is linked to hereditary ciliopathies with a wide phenotypic spectrum. Despite their significance, the specific roles of cilia in different cell types remain poorly understood due to limitations in analyzing ciliary protein composition. We employed antibody-based spatial proteomics to expand the Human Protein Atlas to primary cilia. Our analysis identified the subciliary locations of 715 proteins across three cell lines, examining 128,156 individual cilia. We found that 69% of the ciliary proteome is cell-type specific, and 78% exhibited single-cilia heterogeneity. Our findings portray cilia as sensors tuning their proteome to effectively sense the environment and compute cellular responses. We identified 91 novel cilia proteins and found a genetic candidate variant in CREB3 in one clinical case with features overlapping ciliopathy phenotypes. This open, spatial cilia atlas advances research on cilia and ciliopathies.

cell biology↗

FLEXIQuant-LF: Robust Regression to Quantify Protein Modification Extent in Label-Free Proteomics Data

Improvements in LC-MS/MS methods and technology have enabled the identification of thousands of modified peptides in a single experiment. However, protein regulation by post-translational modifications (PTMs) is not binary, making methods to quantify the modification extent crucial to understanding the role of PTMs. Here, we introduce FLEXIQuant-LF, a software tool for large-scale identification of differentially modified peptides and quantification of their modification extent without prior knowledge of the type of modification. We developed FLEXIQuant-LF using label-free quantification of unmodified peptides and robust linear regression to quantify the modification extent of peptides. As proof of concept, we applied FLEXIQuant-LF to data-independent-acquisition (DIA) data of the anaphase promoting complex/cyclosome (APC/C) during mitosis. The unbiased FLEXIQuant-LF approach to assess the modification extent in quantitative proteomics data provides a better understanding of the function and regulation of PTMs. The software is available at https://github.com/SteenOmicsLab/FLEXIQuantLF.

bioinformatics↗