Biology subjects

Chen, Y. L.

Publications and source records attributed to Chen, Y. L..

6 recordsLinked to original sources

bioRxiv2025

Deletion of RSK2 kinase alleviates age-dependent hypertension

BackgroundHypertension prevalence increases with age, reaching over 70% of people over age 65. The underlying mechanisms are poorly understood. This study interrogates a new signaling pathway in vascular smooth muscle of aged mice driven by p90 ribosomal S6 kinase, RSK2, and its role in increasing peripheral vascular resistance and blood pressure (BP). MethodsBasal BP measurements were taken at 26-29 month (812-892 day) old mice with global deletion of RSK2 (Rsk2-/-) prior to and following treatment with L-NAME. Cardiac function, vessel stiffness, myogenic responses, Ca2+events, contractility, immuno-staining, histology studies and western blotting were performed. ResultsResting BP and myogenic vasoconstriction were normal in aged global Rsk2-/- mice and elevated in wild type (WT) littermates. L-NAME treatment increased BP in aged Rsk2+/+ but not aged Rsk2-/-. Vessel stiffness and glycation collagen crosslinking increased in both aged Rsk2+/+ and Rsk2-/- compared to young vessels with no remodeling or increase in collagen content, even though BP in aged Rsk2-/- arterioles was normal. Increased vessel stiffness was dissociated from increased BP. Ca2+ transients increased and sensitivity to NO-induced relaxation decreased in aged Rsk2+/+ compared to young WT arterioles. IEL structures, eNOS and Hb distribution at myoendothelial junctions were disturbed impairing vasorelaxation in aged Rsk2+/+ but not aged Rsk2-/- arterioles. ConclusionsRSK2 plays a significant role in hypertension associated with aging by downregulating prorelaxant signaling and promoting procontractile events in the vasculature, offering potential new therapeutic targets.

physiology↗

bioRxiv2022

RNA triplex structures revealed by WAXS-driven MD simulations

RNA triple helices are commonly observed tertiary motifs that are increasingly associated with critical biological functions, including signal transduction. Because the recognition of their biological importance is relatively recent, their full range of structures and function has not yet been elucidated. The integration of solution wide-angle X-ray scattering (WAXS) with data-driven molecular dynamics (MD) simulations, described here, provides a new way to capture the structures of major-groove RNA triplexes that evade crystallographic characterization. This method yields excellent agreement between measured and computed WAXS profiles, and allows for an atomically detailed visualization of these motifs. Using correlation maps, the relationship between well-defined features in the scattering profiles and real space characteristics of RNA molecules is easily defined, including the subtle conformational variations in the double-stranded RNA upon the incorporation of a third strand by base-triples. This readily applicable approach provides unique insight into some of the interactions that stabilize RNA tertiary structure and enable function.

biophysics↗

bioRxiv2021

The polyanionic drug suramin neutralizes histones and prevents endotheliopathy

Drugs are needed to protect against the neutrophil-derived histones responsible for endothelial injury in acute inflammatory conditions such as trauma and sepsis. Heparin and other polyanions can neutralize histones but may cause secondary, deleterious effects such as excessive bleeding. Here, we demonstrate that suramin--a widely available polyanionic drug--completely neutralizes the toxic effects of histones. The sulfate groups on suramin form stable electrostatic interactions with hydrogen bonds in the histone octamer with a dissociation constant of 250 nM. In cultured endothelial cells (Ea.Hy926), histone-induced thrombin generation was significantly decreased by suramin. In isolated murine blood vessels, suramin abolished aberrant endothelial cell calcium signals and rescued impaired endothelial-dependent vasodilation caused by histones. Suramin significantly decreased pulmonary endothelial cell ICAM-1 expression and neutrophil recruitment caused by infusion of sub-lethal doses of histones in vivo. Suramin also prevented lung edema, intra-alveolar hemorrhage and mortality in mice receiving a lethal dose of histones. Protection of vascular endothelial function from histone-induced damage is a novel mechanism of action for suramin with therapeutic implications for conditions characterized by elevated histone levels. Significance StatementPathologic levels of circulating histones cause acute endotheliopathy, characterized by widespread disruption of critical endothelial functions and thromboinflammation. We discovered that suramin binds histones and prevents histone-induced endothelial dysfunction, thrombin generation, lung injury, and death. Histone binding is a novel mechanism of action for suramin, considered among the safest and most effective drugs by the World Health Organization. These results support the use of suramin for protection of blood vessels in conditions exacerbated by circulating histones including trauma and sepsis.

immunology↗

bioRxiv2021

Endothelial Pannexin 1-TRPV4 channel signaling lowers pulmonary arterial pressure

Pannexin 1 (Panx1) is an ATP-efflux channel that controls endothelial function in the systemic circulation. However, the roles of endothelial Panx1 in resistance-sized pulmonary arteries (PAs) are unknown. Extracellular ATP dilates PAs through activation of endothelial TRPV4 (transient receptor potential vanilloid 4) ion channels. We hypothesized that endothelial Panx1-ATP- TRPV4 channel signaling promotes vasodilation and lowers pulmonary arterial pressure (PAP). Endothelial, but not smooth muscle, knockout of Panx1 or TRPV4 increased PA contractility and raised PAP. Panx1-effluxed extracellular ATP signaled through purinergic P2Y2 receptor (P2Y2R) to activate protein kinase C (PKC), which in turn activated endothelial TRPV4 channels. Finally, caveolin-1 provided a signaling scaffold for endothelial Panx1, P2Y2R, PKC, and TRPV4 channels in PAs, promoting their spatial proximity and enabling signaling interactions. These results indicate that endothelial Panx1-P2Y2R-TRPV4 channel signaling, facilitated by caveolin-1, reduces PA contractility and lowers PAP.

biochemistry↗

bioRxiv2019

Categorical Assignment of Pulmonary Embolism is a Simple and More Accurate Indicator of Right Ventricular Dysfunction and Short Team Mortality

Several risk stratification tools are available to predict short-term mortality in patients with acute pulmonary embolism (PE). Right ventricular (RV) dysfunction, which is common to intermediate and high risk PE, is an independent predictor of mortality and may be a faster and simpler way to assess patient risk in acute care settings. We evaluated 571 patients presenting with acute PE as the primary diagnosis, stratifying them by the Pulmonary Embolism Severity Index (PESI), by the BOVA score, or categorically as low risk (no RV dysfunction by imaging), intermediate risk (RV dysfunction by imaging), or high risk PE (RV dysfunction by imaging with sustained hypotension). Using imaging data to firstly define the presence of RV dysfunction, and plasma cardiac troponin T (cTnT) and NT-proBNP as additional evidence for myocardial strain, we evaluated the PESI and BOVA scoring systems compared to categorical assignment of PE as low risk, submassive, and massive PE. Cardiac biomarkers poorly distinguished between PESI classes and BOVA stages in patients with acute PE. Cardiac TnT and NT-proBNP easily distinguished low risk from submassive PE with an area under the curve (AUC) of 0.84 (95% C.I. 0.73 - 0.95, p< 0.0001), and 0.88 (95% C.I. 0.79-0.97, p< 0.0001), respectively, and low risk from massive PE with an area under the curve (AUC) of 0.89 (95% C.I. 0.78 - 1.00, p< 0.0001), and 0.89 (95% C.I. 0.82-0.95, p< 0.0001), respectively. Predicted short-term mortality by PESI score or BOVA stage was lower than the observed mortality for submassive PE by a two-fold order of magnitude. These data suggest the presence of RV dysfunction in the context of acute PE is sufficient for the purposes of risk stratification, while more complicated risk stratification algorithms may under-estimate short-term mortality risk.

biochemistry↗

bioRxiv2019

Targeting the trypanosome kinetochore with CLK1 protein kinase inhibitors

The kinetochore is a macromolecular structure that assembles on the centromeres of chromosomes and provides the major attachment point for spindle microtubules during mitosis. In Trypanosoma brucei the proteins that make up the kinetochore are highly divergent, with the inner kinetochore comprising at least 20 distinct and essential proteins (KKT1-20) that include four protein kinases, CLK1 (KKT10), CLK2 (KKT19), KKT2 and KKT3. We performed a phenotypic screen of T. brucei bloodstream forms with a Novartis kinase-focused inhibitor library, which identified a number of selective inhibitors with potent pan-kinetoplastid activity. Deconvolution of an amidobenzimidazole series using a selection of 37 T. brucei mutants that over-express known essential protein kinases identified CLK1 as the primary target. Biochemical studies show that the irreversible competitive inhibition of CLK1 is dependent on a Michael acceptor forming an irreversible bond with C215 in the ATP binding pocket, a residue that is not present in human CLK1, thereby providing selectivity. Chemical inhibition of CLK1 impairs inner kinetochore recruitment and compromises cell cycle progression, leading to cell death. We show that KKT2 is a substrate for CLK1 and identify phosphorylation of S508 to be essential for KKT2 function and for kinetochore assembly. We propose that CLK1 is part of a novel signalling cascade that controls kinetochore function via phosphorylation of the inner kinetochore protein kinase KKT2. This work highlights a novel drug target for trypanosomatid parasitic protozoa and a new chemical tool for investigating the function of their divergent kinetochores.

microbiology↗