Biology subjects

Ludwig, K. R.

Publications and source records attributed to Ludwig, K. R..

4 recordsLinked to original sources

bioRxiv2026

Integrated Multiomics Links Metabolic and Inflammatory Remodeling to Arterial Stiffness After the 4,486-km Trans Europe Footrace

RationaleRegular aerobic exercise protects against vascular aging and reshapes the circulating molecular milieu, but the relation between vascular function, circulating molecules, and exercise dose at extreme volumes remains poorly defined. The vascular and molecular consequences of chronic, multi-stage ultra-endurance running are particularly unclear. ObjectiveTo define circulating molecular signatures associated with vascular dysfunction following the 64-stage, 4,486-km Trans Europe Foot Race (TEFR). Methods and ResultsIntegrated multiomics analysis (proteomics, lipidomics, metabolomics) of plasma from 27 finishers revealed a coordinated systemic shift driving an oxidative phenotype. Specifically, we identified altered arginine metabolism and a universal upregulation of lipotoxic ceramides consistent with incomplete fatty acid oxidation. In conjunction, we identified upregulation of innate immune system pathways including the acute phase response and the complement system. Central pulse wave velocity (cPWV) increased significantly after the race, consistent with arterial stiffening. To test whether the post-race circulating milieu could directly influence vascular mechanics, naive murine aortic rings were incubated with participant plasma. Post-race plasma acutely increased aortic elastic modulus, and this effect was attenuated by the superoxide dismutase mimetic TEMPOL, supporting a ROS-dependent component. In human aortic endothelial cells (HAECs), post-race plasma increased reactive oxygen species generation without detectable changes in eNOS phosphorylation, total eNOS abundance, or stimulated nitric oxide production. Endothelial ROS responses were associated with components of the terminal complement pathway. ConclusionsExtreme multi-stage ultra-endurance exercise induces a distinct systemic milieu associated with arterial stiffening through ROS-sensitive mechanisms. This response is characterized by remodeling of arginine-related metabolism, ceramide accumulation, innate immune activation, and oxidative stress, without evidence of reduced measured eNOS abundance or stimulated NO production. These findings identify candidate molecular pathways linking prolonged metabolic stress to vascular dysfunction.

physiology↗

bioRxiv2025

Cellular Senescence Mediates Doxorubicin Chemotherapy-Induced Aortic Stiffening: Role of Glycation Stress

BackgroundMechanisms underlying Doxorubicin (Doxo) chemotherapy-induced aortic stiffening are incompletely understood. ObjectivesDetermine the role of cellular senescence and the senescence-associated secretory phenotype (SASP) in mediating Doxo-induced aortic stiffening and the influence of senolytic therapy. MethodsAortic stiffness (aortic pulse-wave velocity [PWV]), and associated mechanisms were assessed in young adult p16-3MR mice, a model that allows for genetic-based clearance of senescent cells with ganciclovir [GCV]. Young (4-6 month) mice were injected with Doxo and subsequently treated with GCV or the senolytic ABT263. We evaluated the influence of SASP-associated circulating factors in plasma (the circulating SASP milieu) in mediating aortic stiffening ex vivo (aortic elastic modulus) and examined the contribution of glycation stress. ResultsDoxo increased aortic PWV (425D{+/-}D6 vs. control, 353D{+/-}D5Dcm/sec; P<0.05), an effect prevented by both GCV (348D{+/-}D4Dcm/sec) and ABT263 (342D{+/-}D7Dcm/sec; P<0.05 for both vs. Doxo). Plasma from Doxo-treated mice induced aortic stiffening ex vivo (P<0.05 vs. plasma from control mice), whereas plasma from Doxo-GCV and Doxo-ABT263 groups did not. Glycation stress was implicated in SASP-mediated aortic stiffening with Doxo, as inhibition of receptor mediated glycation stress signaling attenuated plasma-induced aortic stiffening. ConclusionCellular senescence and the circulating SASP milieu contribute to Doxo-induced aortic stiffening. Senolytics hold promise for preserving aortic stiffening following Doxo exposure. Translational perspectiveChemotherapy-induced cardiovascular toxicity is a concern for cancer survivors. This study identifies cellular senescence and the senescence-associated secretory phenotype (SASP) as underlying mechanisms of doxorubicin chemotherapy-induced aortic stiffening - an antecedent to overt cardiovascular disease (CVD). We also provide complementary lines of evidence that glycation stress mediates the mechanistic link between doxorubicin, cellular senescence, the SASP and aortic stiffening. Lastly, we demonstrate the efficacy of senolytic therapy for targeting cellular senescence, the SASP and glycation stress to prevent doxorubicin-induced aortic stiffening. These results offer a novel and clinically actionable approach to preserving vascular health in cancer survivors and mitigating CVD risk.

physiology↗

bioRxiv2023

EWSR1's visual modalities are defined by its association with nucleic acids and RNA polymerase II

We report systematic analysis of endogenous EWSR1s cellular organization. We demonstrate that EWSR1, which contains low complexity and nucleic acid binding domains, is present in cells in faster and slower-recovering fractions, indicative of a protein undergoing both rapid exchange and longer-term interactions. The employment of complementary high-resolution imaging approaches shows EWSR1 exists in in two visual modalities, a distributed state which is present throughout the nucleoplasm, and a concentrated state consistent with the formation of foci. Both EWSR1 visual modalities localize with nascent RNA. EWSR1 foci concentrate in regions of euchromatin, adjacent to protein markers of transcriptional activation, and significantly colocalize with phosphorylated RNA polymerase II. Interestingly, EWSR1 and FUS, another FET protein, exhibit distinct spatial organizations. Our results contribute to bridging the gap between our understanding of the biophysical and biochemical properties of FET proteins, including EWSR1, their functions as transcriptional regulators, and the participation of these proteins in tumorigenesis and neurodegenerative disease. SUMMARYRajan et al. report the visualization of endogenous EWSR1. EWSR1 exists in two visual modalities in the nucleoplasm, one distributed and one as foci. Both EWSR1 modalities localize with nascent RNA. EWSR1 foci concentrate in regions of euchromatin and colocalize with phosphorylated RNA polymerase II.

cell biology↗

bioRxiv2022

HNRNPH1 destabilizes the G-quadruplex structures formed by G-rich RNA sequences that regulate the alternative splicing of an oncogenic fusion transcript

In the presence of physiological monovalent cations, thousands of RNA G-rich sequences can form parallel G-quadruplexes (G4s) unless RNA-binding proteins inhibit, destabilize, or resolve the formation of such secondary RNA structures. Here, we have used a disease-relevant model system to investigate the biophysical properties of the RNA-binding protein HNRNPH1s interaction with G-rich sequences. We demonstrate the importance of two EWSR1-exon 8 G-rich regions in mediating the exclusion of this exon from the oncogenic EWS-FLI1 transcripts expressed in a subset of Ewing sarcomas, using complementary analysis of tumor data, long-read sequencing, and minigene studies. We determined that HNRNPH1 binds the EWSR1-exon 8 G-rich sequences with low nM affinities irrespective of whether in a non-G4 or G4 state but exhibits different kinetics depending on RNA structure. Specifically, HNRNPH1 associates and dissociates from G4-folded RNA faster than the identical sequences in a non-G4 state. Importantly, we demonstrate using gel shift and spectroscopic assays that HNRNPH1, particularly the qRRM1-qRRM2 domains, destabilizes the G4s formed by the EWSR1-exon 8 G-rich sequences in a non-catalytic fashion. Our results indicate that HNRNPH1s binding of G-rich sequences favors the accumulation of RNA in a non-G4 state and that this contributes to its regulation of RNA processing.

molecular biology↗