Biology subjects

Linne, U.

Publications and source records attributed to Linne, U..

5 recordsLinked to original sources

bioRxiv2026

Discovery of a Cell-Permeable Gi-Signaling Inhibitor

Heterotrimeric G proteins regulate diverse physiological processes, yet selective small molecule modulators for the Gi subfamily remain scarce. Here, we employed native metabolomics to screen a fungal culture collection for G protein binders, which led to the discovery of N-hydroxyapiosporamide (NHAP), a fungal specialized metabolite that functionally inhibits Gi-signaling. NHAP selectively binds Gi1 and diminishes Gi1-mediated GTP turnover in biochemical assays. In primary ventricular cardiomyocytes, NHAP largely reversed acetylcholine-induced negative inotropy, demonstrating functional Gi-signaling blockade in a physiological context without acute cytotoxicity. This work establishes NHAP as a first-in-class Gi-selective inhibitor, providing a cell-permeable chemical scaffold for the optimization of next-generation agents to control Gi-signaling in cell-based systems and, ultimately, to target Gi1-driven pathologies.

biochemistry↗

bioRxiv2025

PERK inhibition rewires translational and CMGC protein kinase networks into an antiviral state

Protein kinases (PKs) are central regulators of cellular signaling, yet only a small fraction of the human kinome is targeted therapeutically, and kinase-substrate relationships remain incompletely defined. Here, we systematically characterize kinome regulation during human coronavirus 229E (HCoV-229E) infection across transcriptomic, translational, proteomic, and phospho-proteomic layers. We reveal that pharmacological inhibition of the ER stress sensor kinase PERK reprograms host protein biosynthesis and phospho-proteomic landscapes, simultaneously blocking viral nucleocapsid phosphorylation and modulating multiple host kinases. This rewiring antagonizes virus-induced translational shutdown, along with pronounced regulation of the CMGC kinase family, a pattern conserved in SARS-CoV and SARS-CoV-2 infected cells. Comparative analyses with PERK depletion distinguish on-target from off-target effects of PERK inhibition. Our findings uncover the kinome-scale consequences of PERK perturbation in coronavirus infection and demonstrate how the polypharmacology of PERK inhibitors can be harnessed to establish a potent antiviral state, revealing new avenues for host-directed antiviral strategies.

systems biology↗

bioRxiv2024

Cyclase-associated protein 1 (CAP1) represses MRTF-SRF-dependent gene expression in the mouse cerebral cortex

Serum response factor (SRF) is a ubiquitously expressed transcription factor essential for brain development and function. SRF activity is controlled by two competing classes of coactivators, myocardin-related transcription factors (MRTF) and ternary complex factors (TCF), which introduce specificity into gene expression programs. To date, only few brain studies investigated upstream regulatory mechanisms, which mainly focused on TCF. Since an inhibitory function of monomeric actin towards MRTF-SRF signaling is well-established, we hypothesized a regulatory role for the key actin regulator ADF/cofilin. Surprisingly, ADF/cofilin was largely dispensable for neuronal MRTF-SRF activity. Instead, reporter assays combined with pharmacological and genetic approaches in isolated mouse neurons identified cyclase-associated protein 1 (CAP1) as an important regulator of this pathway. CAP1 promotes cytosolic MRTF retention and represses neuronal MRTF-SRF signaling via an actin-dependent mechanism that requires two specific protein domains. Further, deep RNA sequencing and mass spectrometry in mutant mice proved CAP1s in vivo relevance for this pathway in the cerebral cortex, and led to the identification of neuronal MRTF-SRF target genes. Together, we identified CAP1 as a novel and crucial repressor of neuronal MRTF-SRF signaling.

neuroscience↗

bioRxiv2024

The proximity-based protein interaction landscape of the transcription factor p65 NF-kappaB/RELA and its gene-regulatory logics

The protein interactome of p65 / RELA, the most active subunit of the transcription factor (TF) NF-{kappa}B, has not been previously determined in living cells. Using p65-miniTurbo fusion proteins, we identified by biotin tagging > 350 RELA interactors from untreated and IL-1-stimulated cells, including many TFs (47 % of all interactors) and > 50 epigenetic regulators belonging to different classes of chromatin remodeling complexes. According to point mutants of p65, the interactions primarily require intact dimerization rather than DNA binding properties. A targeted RNAi screen for 38 interactors and subsequent functional transcriptome and bioinformatics studies identified gene regulatory (sub)networks, each controlled by RELA in combination with one of the TFs ZBTB5, GLIS2, TFE3 / TFEB or S100A8 / A9. The remarkably large, dynamic and versatile high resolution interactome of RELA and its gene-regulatory logics provides a rich resource and a new framework for explaining how RELA cooperativity determines gene expression patterns. HighlightsO_LIIdentification of > 350 largely dimerization-dependent interactors of p65 / RELA by miniTurboID C_LIO_LIThe interactome is dominated by transcription factors and epigenetic regulator complexes C_LIO_LIFunctional validation of 38 high confidence interactors by targeted siRNA screen C_LIO_LIIdentification of genetic networks regulated by RELA and six of its interactors in the IL-1 response C_LI

molecular biology↗

bioRxiv2020

Inhibiting coronavirus replication in cultured cells by chemical ER stress

Coronaviruses (CoVs) are important human pathogens for which no specific treatment is available. Here, we provide evidence that pharmacological reprogramming of ER stress pathways can be exploited to suppress CoV replication. We found that the ER stress inducer thapsigargin efficiently inhibits coronavirus (HCoV-229E, MERS-CoV, SARS-CoV-2) replication in different cell types, (partially) restores the virus-induced translational shut-down, and counteracts the CoV-mediated downregulation of IRE1 and the ER chaperone BiP. Proteome-wide data sets revealed specific pathways, protein networks and components that likely mediate the thapsigargin-induced antiviral state, including HERPUD1, an essential factor of ER quality control, and ER-associated protein degradation complexes. The data show that thapsigargin hits a central mechanism required for CoV replication, suggesting that thapsigargin (or derivatives thereof) may be developed into broad-spectrum anti-CoV drugs. One Sentence Summary / Running titleSuppression of coronavirus replication through thapsigargin-regulated ER stress, ERQC / ERAD and metabolic pathways

immunology↗