Biology subjects

Szkop, K. J.

Publications and source records attributed to Szkop, K. J..

5 recordsLinked to original sources

bioRxiv2026

RAPPL-Seq Enables Rapid, High-Sensitivity Ribosome Profiling of Scarce Samples

Ribosome profiling is a powerful method for transcriptome-wide monitoring of translation activity in vivo, but its use is limited by lengthy protocols, reliance on specialized equipment and inefficient recovery of ribosome-protected fragments (RPFs). To overcome these challenges, we developed RAPPL-Seq, a magnetic bead-based affinity capture method that enables fast and efficient RPF isolation. RAPPL-Seq achieves high recovery efficiency, short processing time, and robust performance with limited input material. It is broadly applicable across multiple sample types, including cell lines, primary tissues, and human biospecimens. RAPPL-Seq can also be paired with translation inhibitors to characterize inhibitor- and tissue-specific mRNA translation. RAPPL-Seq efficiently captured translatomes of glioblastoma (GBM) and adjacent non-tumor brain tissues from patient biopsies. Together, these findings establish RAPPL-Seq as a straightforward, easily accessible, and highly sensitive approach that extends translatome studies to scarce experimental and clinical samples, opening new avenues for mechanistic insight and therapeutic discovery.

molecular biology↗

bioRxiv2024

Reduction in ETFDH expression optimizes cancer cell bioenergetics

Mitochondrial electron transport flavoprotein (ETF) insufficiency causes metabolic diseases known as a multiple acyl-CoA dehydrogenase deficiency (MADD). In contrast to muscle, ETFDH is a non-essential gene in acute lymphoblastic leukemia NALM-6 cells, and its expression is reduced across human cancers. ETF insufficiency caused by decreased ETFDH expression limits flexibility of OXPHOS fuel utilization but paradoxically increases cancer cell bioenergetics and accelerates neoplastic growth by activation of the mTORC1/BCL-6/4E-BP1 axis. Collectively, these findings reveal that while ETF insufficiency is rare and has detrimental effects in non-malignant tissues, it is common in neoplasia, where ETFDH downregulation leads to bioenergetic and signaling reprogramming that accelerate neoplastic growth.

cancer biology↗

bioRxiv2023

Epigenetic coordination of transcriptional and translational programs in hypoxia

Adaptation to cellular stresses entails an incompletely understood coordination of transcriptional and post-transcriptional gene expression programs. Here, we quantified hypoxia-dependent transcriptomes, epigenomes, and translatomes in T47D breast cancer cells and H9 human embryonic stem cells. This revealed pervasive changes in transcription start site (TSS) selection associated with nucleosome repositioning and alterations in H3K4me3 distribution. Importantly, hypoxia-associated TSS switching was induced or reversed via pharmacological modulation of H3K4me3 in the absence of hypoxia, defining a role for H3K4me3 in TSS selection independent of HIF1-transcriptional programs. By remodelling 5UTRs, TSS switching selectively alters protein synthesis, including enhanced translation of mRNAs encoding pyruvate dehydrogenase kinase 1 (PDK1) that is essential for the metabolic adaptation to hypoxia. These results demonstrate a previously unappreciated mechanism of translational regulation during hypoxia driven by epigenetic reprogramming of the 5UTRome.

cancer biology↗

bioRxiv2019

flexiMAP: A regression-based method for discovering differential alternative polyadenylation events in standard RNA-seq data

SummaryWe present flexiMAP (flexible Modeling of Alternative PolyAdenylation), a new beta-regression-based method implemented in R, for discovering differential alternative polyadenylation events in standard RNA-seq data. Importantly, flexiMAP allows modeling of multiple known covariates that often confound the results of RNA-seq data analysis. We show, using simulated data, that flexiMAP is very specific and outperforms in sensitivity existing methods, especially at low fold changes. In addition, the tests on simulated data reveal some hitherto unrecognised caveats of existing methods.\n\nAvailabilityThe flexiMAP R package is available at: https://github.com/kszkop/flexiMAP\n\nScripts and data to reproduce the analysis in this paper are available at: https://doi.org/10.5281/zenodo.3238619\n\nContactIrene Nobeli, i.nobeli@bbk.ac.uk

bioinformatics↗

bioRxiv2018

Estrogen receptor alpha controls gene expression via translational offsetting

Estrogen receptor alpha (ER) activity is associated with increased cancer cell proliferation. Studies aiming to understand the impact of ER on cancer-associated phenotypes have largely been limited to its transcriptional activity. Herein, we demonstrate that ER coordinates its transcriptional output with selective modulation of mRNA translation. Importantly, translational perturbations caused by depletion of ER largely manifest as \"translational offsetting\" of the transcriptome, whereby amounts of translated mRNA and protein levels are maintained constant despite changes in mRNA abundance. Transcripts whose levels, but not polysome-association, are reduced following ER depletion lack features which limit translational efficiency including structured 5UTRs and miRNA target sites. In contrast, mRNAs induced upon ER depletion whose polysome-association remains unaltered are enriched in codons requiring U34-modified tRNAs for efficient decoding. Consistently, ER regulates levels of U34-modification enzymes, whereas altered expression of U34-modification enzymes disrupts ER dependent translational offsetting. Altogether, we unravel a hitherto unprecedented mechanism of ER-dependent orchestration of transcriptional and translational programs, and highlight that translational offsetting may be a pervasive mechanism of proteome maintenance in hormone-dependent cancers.

systems biology↗