Biology subjects

Rehling, T.

Publications and source records attributed to Rehling, T..

3 recordsLinked to original sources

bioRxiv2025

Functional characterization of the 9q34.13 locus identifies RAPGEF1 as modulating risk for melanoma and nevi via RAS activation

Genome-wide association studies identified a melanoma- and nevus count-associated locus on chromosome band 9q34.13. Fine-mapping and melanocyte expression data collectively suggest two potential causal genes with opposite association with risk: higher levels of Rap guanine nucleotide exchange factor 1 (RAPGEF1) and lower levels of uridine-cytidine kinase 1 (UCK1). Colocalization analyses and conditional TWAS suggest multiple causal cis-regulatory sequence variants in partial linkage disequilibrium (LD) to each other. Melanocyte capture-HiC and CRISPR-inhibition demonstrated regulatory interactions between fine-mapped variants and the RAPGEF1 and UCK1 promoters. Focusing on RAPGEF1, we demonstrate RAPGEF1 expression promotes melanocyte growth and drives malignant transformation of human immortalized melanocytes. Following treatment with human EGF, RAPGEF1 overexpression activated both RAP1 and RAS. Further, we show RAPGEF1 expression is significantly enriched in melanomas lacking strongly activating RAS-MAPK mutations, suggesting that RAPGEF1 may promote oncogenic RAS-MAPK signaling in melanomas. Furthermore, in these tumors, we provide preliminary evidence to support the prognostic relevance of RAPGEF1 expression in patients lacking RAS or BRAF mutations. Together with other recent studies, these data suggest that germline variation influencing RAS activation may play a key role in nevus development and melanoma risk.

genetics↗

bioRxiv2025

The RNA helicase eIF4A as a novel target in insect cells to combat arboviral infections

Arboviruses transmitted by mosquitoes cause major global health burdens, yet few vaccines or antivirals exist. Targeting host factors required for viral replication offers a promising approach. The DEAD-box RNA helicase eIF4A, a core component of the translation initiation complex eIF4F, unwinds structured 5' UTRs and is critical for many viral RNAs. We tested whether the natural products rocaglates and pateamines, potent eIF4A inhibitors in mammalian cells, also suppress arboviral replication and translation in insect vectors. Silvestrol strongly inhibited Rift Valley fever virus (RVFV) replication in human A549 cells without cytotoxicity, expanding the list of arboviruses dependent on eIF4A. Sequence analysis showed conservation of the rocaglate-binding motif between the arboviral vector Aedes aegypti and the fruit flies Anastrepha suspensa and Drosophila melanogaster. Dual-luciferase assays in insect cells of all three species confirmed silvestrol selectively inhibited translation from purine-rich reporters below cytotoxic thresholds. Purified eIF4A variants retained helicase activity, allowing direct testing of inhibitor interactions. Thermal shift assays demonstrated robust stabilization of eIF4A-RNA complexes by both compound classes in the wildtype proteins, with unexpected rocaglate sensitivity of the putatively insensitive Ae. aegypti H161L mutant, indicating a unique binding pocket geometry of the mosquito protein. Our results identify eIF4A as a conserved and druggable host factor in insects, highlighting its potential as a novel target for transmission-blocking antivirals and insect-specific inhibitors. Author SummaryNatural compounds from the classes of rocaglates and pateamines have shown their potential to inhibit tumor cell growth and to effectively suppress replication of different viruses, including Ebola, corona, picorna, and arboviruses by inhibiting translation initiation through blocking of one of the initiation actors, the helicase eIF4A. eIF4A is needed to unwind structured 5UTRs of selected mRNAs to allow binding of the 43S preinitiation complex. The compounds bind in a pocket of eIF4A, thereby clamping the RNA onto the eIF4A surface. Although eIF4A is highly conserved in eukaryotes not all eIF4A are sensitive to rocaglates. Mainly one key amino acid in the binding pocket determines sensitivity or insensitivity. In this study we expanded the list of arboviruses as potential targets of rocaglate-based drugs. Moreover, we approached the inhibition of arboviral infections from the vector side by studying the interaction between rocaglates and pateamines with eIF4A from the yellow fever mosquito Aedes aegypti, one of the most important arboviral vectors. Our study shows that also the mosquito eIF4A can be targeted by both compound classes. Moreover, our results reveal a unique architecture of the binding pocket that retains sensitivity even upon mutation of the key amino acid.

molecular biology↗

bioRxiv2022

Shared and distinct genetic etiologies for different types of clonal hematopoiesis

Clonal hematopoiesis (CH) - age-related expansion of mutated hematopoietic clones - can differ in frequency and cellular fitness. Descriptive studies have identified a spectrum of events (coding mutations in driver genes (CHIP), gains/losses and copy-neutral loss of chromosomal segments (mCAs), and loss of sex chromosomes). Co-existence of different CH events raises key questions as to their origin, selection, and impact. Here, we report analyses of sequence and genotype array data in up to 482,378 individuals from UK Biobank, demonstrating shared genetic architecture across different types of CH. These data highlighted evidence for a cellular evolutionary trade-off between different forms of CH, with LOY occurring at lower rates in individuals carrying mutations in established CHIP genes. Furthermore, we observed co-occurrence of CHIP and mCAs with overlap at TET2, DNMT3A, and JAK2, in which CHIP precedes mCA acquisition. Individuals carrying these overlapping somatic mutations had a large increase in risk of future hematological malignancy (HR=17.31, 95% CI=9.80-30.58, P=8.94x10-23), which is significantly elevated compared to individuals with non-overlapping CHIP and autosomal mCAs (Pheterogeneity=8.83x10-3). Finally, we leverage the shared genetic architecture of these CH traits to identify 15 novel loci associated with blood cancer risk.

genetics↗