Park, S.-W. | Search bioRxiv

bioRxiv2025

Urolithin A Restores Mitochondrial Function and Reverses Cardiac Remodeling in Heart Failure with Preserved Ejection Fraction

BackgroundHeart failure with preserved ejection fraction (HFpEF) accounts for nearly half of all heart failure cases; however, mechanism-based therapies targeting cellular dysfunction remain absent. Emerging evidence suggests that mitochondrial dysfunction and impaired quality control, particularly defective mitophagy, are central to the pathogenesis of HFpEF. Urolithin A (UA), a gut microbiome-derived postbiotic metabolite, has shown promise as a mitophagy activator in preclinical models; however, its therapeutic efficacy in HFpEF remains unknown. MethodsWe used a clinically relevant two-hit HFpEF mouse model (high-fat diet (HFD) plus N{omega}-nitro-L-arginine methyl ester (L-NAME)) and co-administered UA during disease progression. The cardiac structure and function were assessed using echocardiography, histology, and transmission electron microscopy. Mitochondrial bioenergetics were evaluated using Seahorse-based respirometry. Mitophagy flux was monitored using mt-Keima assays in H9c2 cells and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Mechanistic insights were obtained using immunoblotting, integrated shotgun metagenomic and lipidomic profiling, and single-nucleus RNA sequencing (snRNA-seq). ResultsUA treatment significantly attenuated cardiac remodeling and fibrosis in HFpEF mice while improving diastolic function parameters. Transmission electron microscopy revealed restoration of the mitochondrial ultrastructure, and mitochondrial stress tests demonstrated enhanced oxidative phosphorylation capacity and glycolytic reserves. Immunoblot assays revealed that UA treatment recovered PINK1/Parkin-mediated mitophagy markers (reduced LC3-II and p62/SQSTM1). Mt-Keima assays confirmed enhanced mitophagic flux in H9c2 cells under HFpEF-like stress conditions. Integrated metagenomics and lipidomics revealed significant reductions in cardiovascular risk-associated ceramides. snRNA-seq demonstrated that HFpEF-like stress downregulated contractile, calcium-handling, and mitochondrial mitophagy gene programs. UA treatment restored the mitochondrial quality control signatures and normalized profibrotic and conduction-type cell populations. ConclusionsUrolithin A restored mitochondrial quality control through the activation of mitophagy and reversed cardiac remodeling in HFpEF. These findings establish UA as a mitochondria-targeted therapeutic candidate for HFpEF. Novelty and SignificanceO_ST_ABSWhat is known?C_ST_ABS{checkmark} Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome driven by metabolic stress and myocardial remodeling, for which effective disease-modifying therapies are lacking. {checkmark}Mitochondrial dysfunction and impaired mitophagy have been implicated in HFpEF, but their roles in cardiomyocyte state remodeling and fibrosis remain incompletely defined. {checkmark}Urolithin A, a gut microbiome-derived metabolite, enhances mitophagy in aging and metabolic tissues, but its relevance to HFpEF has not been established. What new information does this article contribute?{checkmark} Urolithin A restores mitochondrial quality control and mitophagic flux in cardiomyocytes, improving diastolic function and attenuating cardiac remodeling in a two-hit HFpEF model. {checkmark}Integrated metagenomic and lipidomic analyses identify suppression of gut microbiome-associated ceramide biosynthesis as a systemic mechanism linked to Urolithin A-mediated cardioprotection. {checkmark}Single-nucleus RNA sequencing reveals that Urolithin A reverses maladaptive cardiomyocyte transcriptional state transitions toward fibrogenic and conduction-like programs.

molecular biology↗

bioRxiv2025

Testing Sensorimotor Timing in a Living Laboratory: Behavioral Signatures of a Neural Oscillator

Rhythmic ability has been studied for more than a century in laboratory settings testing timed finger taps. While robust results emerged, it remains unclear whether these findings reflect behavioral limitations in realistic scenarios. This study tested the synchronization-continuation task in a museum with 455 visitors of a wide variety of ages (5-74yrs), musical experiences (0-40yrs) and educational and cultural backgrounds. Adopting a dynamic systems perspective, three metronome pacing periods were anchored around each individuals preferred tempo, and 20% faster and 20% slower. Key laboratory findings were replicated and extended: timing error and variability decreased during childhood and increased in older adults and were lower, even with moderate musical experience. Consistent with an oscillator perspective, timing at non-preferred tempi drifted toward their preferred rate. Overall, these findings demonstrate that timing limitations may reflect attractor properties of a neural oscillator and its signature is still present even in noisy, naturalistic settings.

neuroscience↗

bioRxiv2022

Measuring Capillary Flow Dynamics using Interlaced Two-Photon Volumetric Scanning

Two photon microscopy and optical coherence tomography (OCT) are two standard methods for measuring flow speeds of red blood cells in microvessels, particularly in animal models. However, traditional two photon microscopy lacks the depth of field to adequately capture the full volumetric complexity of the cerebral microvasculature and OCT lacks the specificity offered by fluorescent labeling. In addition, the traditional raster scanning technique utilized in both modalities requires a balance of image frame rate and field of view, which severely limits the study of RBC velocities in the microvascular network. Here, we overcome this by using a custom two photon system with an axicon based Bessel beam to obtain volumetric images of the microvascular network with fluorescent specificity. We combine this with a novel scan pattern that generates pairs of frames with short time delay sufficient for tracking red blood cell flow in capillaries. We track flow speed in 10 or more capillaries simultaneously at 1 Hz in a 237 m x 237m x 120 m volume and quantify both spatial and temporal variability in speed. We also demonstrate the ability to track flow speed changes around stalls in capillary flow.

bioengineering↗

bioRxiv2021

Flexible Simultaneous Mesoscale Two-Photon Imaging of Neural Activity at High Speeds

Understanding brain function requires monitoring local and global brain dynamics. Two-photon imaging of the brain across mesoscopic scales has presented trade-offs between imaging area and acquisition speed. We describe a flexible cellular resolution two-photon microscope capable of simultaneous video rate acquisition of four independently targetable brain regions spanning an approximate five-millimeter field of view. With this system, we demonstrate the ability to measure calcium activity across mouse sensorimotor cortex at behaviorally relevant timescales.

neuroscience↗