Biology subjects

Visnes, T.

Publications and source records attributed to Visnes, T..

4 recordsLinked to original sources

bioRxiv2026

A high-throughput screening dataset of small-molecule inhibitors across human DNA glycosylases

The base excision repair pathway removes small base lesions from DNA and is initiated in humans by one of eleven DNA glycosylases with overlapping substrate specificities. Despite their central role in genome maintenance and transcription, systematic datasets describing small-molecule binders or inhibitors of DNA glycosylases are lacking. Here, through a collaborative effort across Scandinavia, we establish a high-throughput biochemical assay platform for human DNA glycosylases and use it to generate a systematic small-molecule screening dataset. A chemogenomic library was screened against nine glycosylases with assays of sufficient quality for hit identification, yielding primary screening and concentration-response data and identifying multiple previously unreported inhibitors. All primary and processed data, along with detailed assay protocols and metadata, are publicly available to support reuse in chemical biology, further compound optimization, assay development and comparative studies of DNA repair enzymes.

biochemistry↗

bioRxiv2025

High-content morphological profiling by Cell Painting in 3D spheroids.

Cell Painting is a popular assay for morphological profiling of multi-labeled 2D monolayer cell cultures used in a wide range of applications. Culturing cells in 3D has potential for higher physiological relevance, such as when studying effects of perturbations. Robust and scalable 3D models can be challenging to characterize through imaging - particularly because light has difficulty penetrating cell multilayers. We introduce a scalable method where the Cell Painting assay is combined with tissue-clearing and applied to 3D spheroids generated in a ULA microplate format. Multi-channel images are acquired using confocal microscopy, and cells can be segmented inside those spheroids allowing for relevant morphological features to be extracted. Our end-to-end analysis pipeline comprises cell segmentation, morphological feature extraction, and between-spheroids and within-spheroid normalization. We demonstrate the method using spheroids cultured from two colorectal cancer cell lines and successfully detect distinct phenotypic changes upon compound treatments, on both spheroid-level using maximum intensity projections and on single cell-level. We show that drugs group by mechanism of action, with biologically relevant clusters especially evident with single-cell data. Finally, we contrast our method to results from 2D Cell Painting and discover a different pattern in DNA damaging drugs in HCT116 colorectal cancer cells. This work lays the foundation for multi-channel image-based screening in 3D spheroids.

pharmacology and toxicology↗

bioRxiv2024

Functional Impact of Nth-like DNA glycosylase on Mitochondrial Dynamics

NTH-like DNA glycosylase (NTHL1), a key enzyme in the base excision repair (BER) pathway, has long been considered essential for maintaining both nuclear and mitochondrial genome integrity. In this study, we integrate in vitro biochemical assays, in-cellulo molecular biology experiments, and bioinformatic analyses to investigate the impact of NTHL1 loss on mitochondrial DNA (mtDNA) stability and function. Our findings challenge the conventional view by showing that the loss of NTHL1 confers a positive phenotype. Although NTHL1 deletion in human cells results in a significant accumulation of mtDNA lesions, it is unexpectedly accompanied by a substantial increase in mtDNA copy number (CN), which correlates with elevated oxidative phosphorylation (OXPHOS) protein levels and enhanced mitochondrial respiratory capacity. Additionally, NTHL1-knockout cells exhibit larger mitochondria and increased levels of the mitochondrial biogenesis regulator peroxisome proliferator-activated receptor {gamma} coactivator 1 (PGC1) and the membrane fusion protein Dynamin-like GTPase OPA1. These changes suggest an adaptive response to stress or altered cellular demands, aimed at enhancing mitochondrial function and capacity. Consequently, NTHL1-knockout cells showed resistance to 1-methyl-4-phenylpyridinium (MPP+)-induced mitochondrial stress along with increased phosphorylation of eIF2. Together, this suggests that the loss of NTHL1 may enhance cellular resilience to oxidative stress by activating protective integrated stress response and mitohormesis pathways thereby contributing to cellular survival under adverse conditions. Collectively, our findings position NTHL1 as a key player in mtDNA stability and mitochondrial function, linking its DNA repair activity to the integrated stress response. Its loss triggers a shift from canonical oxidative phosphorylation to stress-adaptive pathways, ultimately enhancing cellular resistance against oxidative stress through the activation of the mitochondrial hormetic response.

cell biology↗

bioRxiv2019

MTH1 promotes mitotic progression to avoid oxidative DNA damage in cancer cells

BACKGROUNDWe developed MTH1 inhibitors (MTH1i) TH588 and TH1579 showing broad anti-cancer activity, while structurally distinct MTH1i fail to kill cancer cells. Here, we describe a new role of MTH1 in mitosis and the detailed mechanism of action of TH1579 (karonudib) and other structurally distinct MTH1i.\n\nMATERIALS AND METHODSCancer cell lines or zebrafish embryos were treated with MTH1i or siRNA targeting MTH1 and analysed primarily by live cell and immunofluorescence microscopy, survival assays, DNA fibre or COMET assays. MTH1 and tubulin interactions were analysed in vitro using co-immunoprecipitation and tubulin polymerisation assays.\n\nRESULTSHere, we describe a mitotic role for the MTH1 protein, which binds to tubulin, is required for microtubule polymerisation, correct spindle assembly, mitosis progression and suppression reactive oxygen species (ROS) generation in mitosis. Potent MTH1i display differential abilities to break the MTH1-tubulin interaction and cause mitotic arrest, demonstrating 8-oxodGTPase and mitotic function of MTH1 are mechanistically distinct. TH588 and TH1579 have more profound effect on mitotic arrest than other MTH1i explained by additional direct inhibition of tubulin polymerisation. MTH1i only inhibiting 8-oxodGTPase activity synergize with mitotic poisons.\n\nCONCLUSIONSEfficient MTH1 have a dual mechanism of action: inhibiting mitosis (to generate ROS) and promoting 8-oxodGTP incorporation into DNA during mitotic replication, dependent on ROS generation. Direct inhibition of tubulin polymerisation of TH588 and TH1579 increase their ability to arrest cells and generate ROS in mitosis. Furthermore, non-cytotoxic MTH1 can become effective and increase incorporation of oxidised nucleotides into DNA when combined with sub-therapeutic concentrations of mitotic inhibitors or challenged directly by 8-oxodGTP.

cancer biology↗