Biology subjects

Reynolds, E.

Publications and source records attributed to Reynolds, E..

13 recordsLinked to original sources

bioRxiv2026

Lung microvascular rarefaction impairs pulmonary gas exchange and exacerbates heart failure with preserved ejection fraction

BackgroundDyspnea and exercise intolerance are the primary clinical symptoms of heart failure. Heart failure patients experience frequent hypoxemic episodes, yet underlying mechanisms and relevance remain poorly understood. In a cohort of heart failure patients and multiple animal models, we identify pulmonary capillary rarefaction driven by excessive autophagy in endothelial cells as a novel mechanism of hypoxemia and cardiac disease progression. MethodsA cohort of heart failure with preserved ejection fraction (HFpEF) patients was analyzed for parameters of left ventricular (LV) dysfunction and pulmonary gas exchange. Morphological and cellular mechanisms of impaired pulmonary oxygenation were assessed in three animal models of heart failure, namely two HFpEF models, SU5416-treated ZSF1 obese rats and high fat diet/L-NAME treated mice, and in rats subjected to aortic banding. Lung microvascular rarefaction was quantified by micro-computed tomography, stereology, flow cytometry and dye efflux. Cellular mechanisms of capillary loss were analyzed by single-cell transcriptomics, electron microscopy and immunofluorescence, and in mice with endothelial-specific deletion of the autophagy gene Atg7 (Atg7EN-KO). ResultsIn 234 HFpEF patients, advancing NYHA class was associated with progressive worsening of arterial oxygen saturation at rest and during exercise and a reduced lung diffusing capacity. Impaired gas diffusion correlated with indices of LV diastolic dysfunction. Impaired oxygenation and reduced exercise capacity were similarly evident in animal models of left heart disease, which showed a distinct loss of pulmonary microvessels and capillaries. Lung microvascular endothelial cells in HFpEF showed characteristics of increased autophagic flux and apoptosis. Relative to their wild type HFpEF controls, Atg7EN-KO mice had less capillary loss, restored normoxemia, improved exercise tolerance, and mitigated LV diastolic dysfunction. Additional studies in HFpEF mice corroborated the functional relevance of impaired gas exchange for the progression of left heart disease by demonstrating that additional hypoxia aggravated, whereas moderate hyperoxia improved LV function. ConclusionOur findings identify pulmonary microvascular rarefaction as a novel pathomechanism in heart failure that i) contributes to dyspnea and exercise intolerance, ii) impairs pulmonary gas exchange and iii) accelerates LV disease progression. Strategies targeting this axis such as moderate oxygen therapy may mitigate cardiopulmonary morbidity in heart failure. Clinical Trial RegistrationRegistered in the DRKS (Deutsches Register fur klinische Studien) as trial# DRKS00032974 at https://drks.de/search/en/trial/DRKS00032974.

physiology↗

bioRxiv2025

A novel enteric pacemaker activity in Drosophila

Enteric organs such as the gut and stomach display the intrinsic ability to generate slow-wave potentials, rhythmic electrochemical events acting as key regulators of gastrointestinal motility. In mammals, slow waves occur as a result of the pacemaker activity of Interstitial Cells of Cajal (ICCs) which, by recruiting visceral muscles, ultimately lead to peristalsis. Here, we uncover and characterize a novel mechanism in Drosophila by which the midgut is able to generate strong muscular whip-like contractions. This pacemaker activity, here named superstalsis, is only active at certain physiological conditions and is selectively linked to longitudinal visceral muscle activation. Furthermore, we identify in Subdued, an ortholog gene of the ANO1/TMEM16A family, a marker for peristalsis in Drosophila, specifically associated with circular muscle activity. As fasting and bacterial infections cause specific changes in the intestinal motility profiles in vivo, we propose that the gut can autonomously alter the peristalsis/superstalsis balance to efficiently respond to diverse pathological and homeostatic events.

physiology↗

bioRxiv2025

Myeloid cell recruitment propels right ventricular dysfunction in HFpEF via sterile inflammation.

BackgroundIn contrast to what has already been shown in HFpEF associated left ventricular (LV) diastolic dysfunction, leukocytes role in frequently occurring right ventricular dysfunction (RVD) secondary to HFpEF are so far missing, partially due to the lack of suitable small animal models. Here, we follow a translational research approach by establishing a murine HFpEF model developing manifest RVD and analyzed human HFpEF cohorts to study the mechanistic link between leukocytes and RVD in HFpEF. Methods8-week-old male and female C57BL/6J or Cx3cr1CreER/+R26tdTomato/+ mice were divided into four experimental groups: i) chow, ii) HFpEF (N[{omega}]-nitro-l-arginine methyl ester (L-NAME), 60% high-fat diet), iii) chronic hypoxia (10% O2) and iv) HFpEF and hypoxia (RV-HFpEF) to assess bi-ventricular function and myeloid cell dynamics. To test whether myeloid cells are causally involved in the development of RV remodeling in HFpEF, we additionally treated RV-HFpEF mice with the colony stimulating factor 1 receptor inhibitor PLX-5622 (PLX) to deplete myeloid cells. After 12 weeks, all experimental groups were subjected to transthoracic echocardiography, invasive hemodynamics or flow cytometry. ResultsRV-HFpEF resulted in LV diastolic dysfunction indicated by increased E/E ratio, reduced global longitudinal peak strain, smaller end-diastolic diameters and increased isovolumetric relaxation time compared to chow. RV-HFpEF animals developed RV hypertrophy and RVD evident as increased Fultons index and collagen content as well as elevated RV systolic pressures (RVSPs) and reduced tricuspid annular plane systolic excursion, respectively. Flow cytometric analyses revealed elevated total leukocyte, monocyte, and macrophage counts in RV tissue of RV-HFpEF compared to chow or LV tissue from RV-HFpEF animals. These data were confirmed by unbiased proteomic analyses of RV tissue from RV-HFpEF mice, demonstrating increased abundance of proteins involved in activation of the innate immune system, macrophage chemotaxis, cell adhesion and extracellular matrix organization when compared to LV tissue or other experimental groups. Fate mapping experiments revealed that recruited monocyte-derived macrophages became the main source of total cardiac macrophages in RV tissue from RV-HFpEF mice. Depletion of myeloid cells was associated with rescued RVSP profiles compared to RV-HFpEF control mice. In HFpEF patients, RV dilation was associated with an increased percentage of circulating monocytes. In RV biopsies from HFpEF patients, we found increased expression of adhesion molecules, fibrotic markers and inflammatory transcripts. ConclusionWe demonstrate that dysregulated myeloid cell dynamics are associated with, and directly contribute to, the pathogenesis of HFpEF-associated RVD in humans and mice. Clinical PerspectiveWhat is new: O_LIWe explore myeloid cell dynamics in a novel three-hit experimental HFpEF mouse model with RV hypertrophy, RV end-systolic pressure and RV dysfunction. C_LIO_LIIn this model, RV dysfunction was associated with macrophage expansion, monocyte recruitment and extracellular matrix deposition, whilst macrophage depletion partly reversed these changes and rescued RV hemodynamics. C_LIO_LIHFpEF patients with RV dilation or RV dysfunction exhibit unique leukocyte dynamics and inflammatory profiles when compared to HFpEF patients with normal RV function or diameters. C_LI Clinical implications: O_LIThere exists a major clinical discrepancy between high incidence of RV dysfunction associated to HFpEF and a lack of targeted treatment strategies. C_LIO_LIOur novel three-hit mouse model recapitulates many features of the clinical scenario of HFpEF patients with RV dysfunction, therefore representing an important step towards systematic testing and development of targeted treatment options. C_LIO_LISterile inflammation and dysregulation of innate immune cells may be suitable targets for therapeutic interventions against RV dysfunction in HFpEF. C_LI

physiology↗

bioRxiv2025

Neural Spectral Prediction for Structure Elucidation with Tandem Mass Spectrometry

Structural elucidation using untargeted tandem mass spectrometry (MS/MS) has played a critical role in advancing scientific discovery [1, 2]. However, differentiating molecular fragmentation patterns between isobaric structures remains a prominent challenge in metabolomics [3-10], drug discovery [11-13], and reaction screening [14-17], presenting a significant barrier to the cost-effective and rapid identification of unknown molecular structures. Here, we present a geometric deep learning model, ICEBERG, that simulates high-energy collision-induced dissociation in mass spectrometry to generate chemically plausible fragments and their relative intensities with awareness of collision energies and polarities. We utilize ICEBERG predictions to facilitate structure elucidation by ranking a set of candidate structures based on the similarity between their predicted in silico MS/MS spectra and an experimental MS/MS spectrum of interest. This integrated elucidation pipeline enables state-of-the-art performance in compound annotation, with 40% top-1 accuracy on the NIST20 [M+H]+ adduct subset and with 92% of correct structures appearing in the top ten predictions in the same dataset. It achieves 46% top-1 and 86% top-10 accuracies when tested on the open-access MassSpecGym benchmark, and outperforms SIRIUS on a recently released test set with previously uncharacterized structures. We demonstrate several real-world case studies, including identifying clinical biomarkers of depression and tuberculous meningitis, annotating an aqueous abiotic degradation product of the pesticide thiophanate methyl, disambiguating isobaric products in pooled reaction screening, and annotating biosynthetic pathways in Withania somnifera. Overall, this deep learning-based paradigm for structural elucidation enables rapid molecular annotation from complex mixtures, driving discoveries across diverse scientific domains.

bioinformatics↗

bioRxiv2025

Near-atomic structure of the PorKN rings, disulfide bonded to PorG and bound to Attachment Complexes, provide mechanistic insights into the type IX secretion system

The Type IX Secretion System exports proteins across the outer membrane (OM) of bacteria in the Bacteroidota phylum, however, the mechanistic details remain unknown. Here, we present a [~]3.5[A] cryo-EM structure of the periplasmic rings comprising 32-33 subunits each of PorK and PorN. Additionally, we show the presence of a critical disulfide bond between PorK and the PorG OM protein that is essential for protein secretion and demonstrate that the Attachment Complexes bind to and are localized above the PorKN rings. Overall, each ring resembles a cogwheel with PorN forming cog-like projections on the periplasmic side and the flat surface of PorK orienting towards the OM. Given these results, we propose that the PorLM motor drives the rotation of the PorKN cogwheel together with PorG and associated Attachment Complexes, potentially providing the energy to complete protein secretion and the coordinated cell surface attachment of the secreted cargo.

microbiology↗

bioRxiv2024

Elucidation of gene clusters underlying withanolide biosynthesis in ashwagandha through yeast metabolic engineering

Withanolides are medicinally relevant steroidal lactones produced by Withania somnifera (ashwagandha) amongst other Solanaceae family plants. However, the biosynthetic pathway to withanolides is largely unknown, preventing scale-up and hindering pharmaceutical applications. We sequenced the genome of W. somnifera and identified two biosynthetic gene clusters exhibiting a segmented tissue-specific expression pattern. We characterized the cluster enzymes through stepwise pathway reconstitution in yeast and transient expression in Nicotiana benthamiana, leading to the identification of three cytochrome P450s (CYP87G1, CYP88C7, and CYP749B2) and a short-chain dehydrogenase that produce a lactone ring- containing intermediate when co-expressed. A fourth cytochrome P450 (CYP88C10) and a sulfotransferase convert this into an intermediate with the characteristic withanolide A-ring structure, featuring a C1 ketone and C2-C3 unsaturation. The discovery of the sulfotransferase as a core pathway enzyme challenges the conventional paradigm of sulfotransferases as tailoring enzymes. These insights pave the way for an efficient biomanufacturing process for withanolides and future development of withanolide-derived drugs.

biochemistry↗

bioRxiv2024

Mating proximity blinds threat perception.

Romantic engagement can bias sensory perception. This love blindness reflects a common behavioral principle across organisms: favoring pursuit of a coveted reward over potential risks. In the case of animal courtship, such sensory biases may support reproductive success but can also expose individuals to danger, such as predation. How do neural networks balance the trade-off between risk and reward? Here, we discover a dopamine-governed filter mechanism in male Drosophila that reduces threat perception as courtship progresses. We show that during early courtship stages, threat-activated visual neurons inhibit central courtship nodes via specific serotonergic neurons. This serotonergic inhibition prompts flies to abort courtship when they see imminent danger. However, as flies advance in the courtship process, the dopaminergic filter system reduces visual threat responses, shifting the balance from survival to mating. By recording neural activity from males as they approach mating, we demonstrate that progress in courtship is registered as dopaminergic activity levels ramping up. This dopamine signaling inhibits the visual threat detection pathway via Dop2R receptors, allowing male flies to focus on courtship when they are close to copulation. Thus, dopamine signaling biases sensory perception based on perceived goal proximity, in order to prioritize between competing behaviors.

neuroscience↗

bioRxiv2023

Comparative pathogenesis of two lineages of Powassan virus reveals differing routes of neuroinvasion leading to distinct clinical outcome, neuropathology and inflammation

Tick-borne flaviviruses (TBFV) can cause severe neuroinvasive disease which may result in death or long-term neurological deficit in over 50% of survivors. Multiple mechanisms for invasion of the central nervous system (CNS) by flaviviruses have been proposed including axonal transport, transcytosis, endothelial infection, and Trojan horse routes. Flaviviruses may utilize different or multiple mechanisms of neuroinvasion depending on the specific virus, infection site, and host variability. In this work we have shown that infection of BALB/cJ mice with either Powassan virus lineage I (Powassan virus) or lineage II (deer tick virus) results in distinct spatial tropism of infection in the CNS which correlated with unique clinical presentation for each lineage. Comparative transcriptomics of infected brains demonstrates activation of different immune pathways and downstream host responses. Ultimately the comparative pathology and transcriptomics are congruent with different clinical signs in a murine model. These results suggest that different disease presentations would be occur in clinical cases due to the innate differences in the two lineages of Powassan virus. Author SummaryPowassan virus causes a nationally notifiable disease which can cause severe neurological disease in humans and has no approved vaccines or therapeutics. Although two distinct lineages circulate in North America, clinical differentiation is not typically performed, and pathology has been assumed to be similar between lineages. In this work, a direct comparison of lineage I (Powassan virus) and lineage II (deer tick virus) demonstrated distinct differences in the clinical presentation, pathology of the central nervous system, and immune response in immunocompetent mice. These differences suggest that deer tick virus and Powassan virus do not utilize the same mechanisms for neuroinvasion and dissemination within the CNS. This is clinically relevant as the development of treatment plans and therapeutics need to be evaluated for these virus lineages.

microbiology↗

bioRxiv2023

Human Surfactant Protein A Alleviates SARS-CoV-2 Infectivity in Human Lung Epithelial Cells

SARS coronavirus 2 (SARS-CoV-2) infects human angiotensin-converting enzyme 2 (hACE2)-expressing lung epithelial cells through its spike (S) protein. The S protein is highly glycosylated and could be a target for lectins. Surfactant protein A (SP-A) is a collagen-containing C-type lectin, expressed by mucosal epithelial cells and mediates its antiviral activities by binding to viral glycoproteins. This study examined the mechanistic role of human SP-A in SARS-CoV-2 infectivity. The interactions between human SP-A and SARS-CoV-2 S protein and hACE2 receptor, and SP-A level in COVID-19 patients were assessed by ELISA. The effect of SP-A on SARS-CoV-2 infectivity was analyzed by infecting human lung epithelial cells (A549-ACE2) with pseudoviral particles and infectious SARS-CoV-2 (Delta variant) pre-incubated with SP-A. Virus binding, entry, and infectivity were assessed by RT-qPCR, immunoblotting, and plaque assay. The results showed that human SP-A can bind SARS-CoV-2 S protein/RBD and hACE2 in a dose-dependent manner (p<0.01). Human SP-A inhibited virus binding and entry, and reduce viral load in lung epithelial cells, evidenced by the dose-dependent decrease in viral RNA, nucleocapsid protein, and titer (p<0.01). Increased SP-A level was observed in the saliva of COVID-19 patients compared to healthy controls (p<0.05), but severe COVID-19 patients had relatively lower SP-A levels than moderate COVID-19 patients (p<0.05). Therefore, SP-A plays an important role in mucosal innate immunity against SARS-CoV-2 infectivity by directly binding to the S protein and inhibiting its infectivity in host cells. SP-A level in the saliva of COVID-19 patients might serve as a biomarker for COVID-19 severity.

molecular biology↗

bioRxiv2023

Bsc2 is a novel regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation

Cells store lipids in the form of triglyceride (TG) and sterol-ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs, and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal Tld1s HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis, but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, over-expression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.

cell biology↗

bioRxiv2022

Incilius alvarius cell-based synthesis of 5-MeO-DMT

There is growing interest in the therapeutic potential of 5-MeO-DMT (5-methoxy-N,N-dimethyltryptamine) for psychiatric disorders. While 5-MeO-DMT can be chemically synthesized, the parotoid gland secretions of Incilius alvarius (also known as the Colorado River or Sonoran Desert toad) contain 5-MeO-DMT and other molecules including bufotenine, bufagenins, bufotoxins, and indole alkylamines that may have individual clinical utility or act as entourage molecules to enhance the activity of 5-MeO-DMT. Incilius alvarius is currently under severe ecological pressure due to demand for natural 5-MeO-DMT and habitat loss. We established a cell line from tissue obtained by wedge biopsy of the Incilius alvarius parotoid gland and confirmed the cell-based biosynthesis of 5-MeO-DMT by LC-MS/MS. Cell-based biosynthesis of Incilius alvarius parotoid gland secretions is a potentially cruelty-free and sustainable source of naturally derived 5-MeO-DMT for research and drug development. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/492789v3_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@163bfc6org.highwire.dtl.DTLVardef@1c36601org.highwire.dtl.DTLVardef@15ded62org.highwire.dtl.DTLVardef@18bbea8_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2022

Triglyceride lipolysis driven by glucose restriction triggers liquid-crystalline phase transitions and proteome remodeling of lipid droplets

Lipid droplets (LDs) are reservoirs for triglycerides (TGs) and sterol-esters (SEs), but how these lipids are organized within LDs and influence its proteome remains unclear. Using in situ cryoelectron tomography, we show that glucose restriction triggers lipid phase transitions within LDs generating liquid-crystalline lattices inside them. Mechanistically this requires TG lipolysis, which decreases the LD TG:SE ratio, promoting SE transition to a liquid-crystalline phase. Molecular dynamics simulations reveal TG depletion promotes spontaneous TG and SE de-mixing in LDs, additionally altering the lipid packing of the phospholipid monolayer surface. Fluorescence imaging and proteomics further reveal that liquid-crystalline phases are associated with selective remodeling of the LD proteome. Some canonical LD proteins including Erg6 re-localize to the ER network, whereas others remain LD-associated. Model peptide LiveDrop also redistributes from LDs to the ER, suggesting liquid-crystalline-phases influence ER-LD inter organelle transport. Our data suggests glucose restriction drives TG mobilization, which alters the phase properties of LD lipids and selectively remodels the LD proteome.

cell biology↗

bioRxiv2021

Postsynaptic plasticity of cholinergic synapses underlies the induction and expression of appetitive memories in Drosophila

In vertebrates, several forms of memory-relevant synaptic plasticity involve postsynaptic rearrangements of glutamate receptors. In contrast, previous work indicates that Drosophila and other invertebrates store memories using presynaptic plasticity of cholinergic synapses. Here, we provide evidence for postsynaptic plasticity at cholinergic output synapses from the Drosophila mushroom bodies (MBs). We find that the nicotinic acetylcholine receptor (nAChR) subunit 5 is required within specific MB output neurons (MBONs) for appetitive memory induction, but is dispensable for aversive memories. In addition, nAChR 2 subunits mediate memory expression and likely functions downstream of 5 and the postsynaptic scaffold protein Dlg. We show that postsynaptic plasticity traces can be induced independently of the presynapse, and that in vivo dynamics of 2 nAChR subunits are changed both in the context of associative and non-associative memory formation, underlying different plasticity rules. Therefore, regardless of neurotransmitter identity, key principles of postsynaptic plasticity support memory storage across phyla.

neuroscience↗