Biology subjects

Sonkusare, S. K.

Publications and source records attributed to Sonkusare, S. K..

9 recordsLinked to original sources

bioRxiv2026

AKAP5 and Caveolin-1 organize opposing nanodomains that regulate smooth muscle contraction and blood pressure

TRPV4 ion channels in vascular smooth muscle cells (SMCs) are crucial regulators of blood pressure, and their functional effects are differentially shaped by their signaling partners. However, the mechanisms by which TRPV4 channels are compartmentalized into distinct signaling nanodomains with opposite impacts on blood pressure remain unclear. Here, we identify the scaffolding proteins that compartmentalize TRPV4 channels into discrete nanometer-scale signaling domains at the SMC plasma membrane and define how these nanodomains produce opposing effects on vasoconstriction and blood pressure. We show that AKAP5 anchors a nanodomain linking 1-adrenergic receptors, protein kinase C and TRPV4 channels, thereby driving sympathetic vasoconstriction and blood pressure elevation. In contrast, caveolin-1 promotes a mechanosensitive nanodomain comprising Piezo1, TRPV4, and BK channels that mediates vasodilation and a decrease in blood pressure. In hypertension, AKAP5-dependent constrictor nanodomains are hyperactive, whereas caveolin-1-based dilator nanodomains are hypoactive, shifting the balance toward pathological vasoconstriction. These findings reveal fundamental mechanisms that organize smooth muscle TRPV4 channels into spatially and functionally distinct nanodomains regulating blood pressure and show how disruption of this organization contributes to blood pressure elevation in hypertension.

physiology↗

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↗

bioRxiv2024

Microenvironment T-Type calcium channels regulate neuronal and glial processes to promote glioblastoma growth

BackgroundGlioblastoma (GBM) is the most common primary malignant brain tumor. The aim of this study was to elucidate the role of microenvironment and intrinsic T-type calcium channels (Cav3) in regulating tumor growth and progression. MethodsWe grafted syngeneic GBM cells into Cav3.2 knockout mice to assess the role of microenvironment T-Type calcium channels on GBM tumor growth. We performed single-cell RNA-seq (scRNA-seq) of tumors from WT and Cav3.2 KO mice to elucidate the regulation of tumors by the microenvironment. We used neurons from WT and Cav3.2 KO mice in co-culture with GBM stem cells (GSC) to assess the effects of Cav3.2 on neuron/GSC synaptic connections and tumor cell growth. ResultsCav3.2 KO in the microenvironment led to significant reduction of GBM growth and prolongation of animal survival. scRNA-seq showed that microenvironment Cav3.2 regulates neuronal and glial biological processes. Microenvironment Cav3.2 downregulated numerous genes associated with regulating the OPC cell state in GBM tumors such as SOX10 and Olig2. Neuronal Cav3.2 promoted neuron/GSC synaptic connections and GSC growth. Treatment of GSCs with the Cav3 blocker mibefradil downregulated genes associated with neuronal processes. The Cav3 blocker drug mibefradil synergized with temozolomide (TMZ) and radiation to reduce in vivo tumor growth and prolong animal survival. ConclusionsTogether these data reveal a role for microenvironment Cav3 in promoting GBM tumor progression through regulating neuronal and glial processes particularly associated with the OPC-cell state. Targeting both intrinsic and microenvironment Cav3 with the inhibitor mibefradil significantly enhanced the anti-GBM effects of TMZ and radiation. Key PointsO_LIMicroenvironment Cav3.2 promotes GBM progression C_LIO_LIMicroenvironment Cav3.2 promotes neuronal and glial processes C_LIO_LIPharmacological targeting of intrinsic and microenvironment Cav3 synergizes with TMZ/radiation C_LI Importance of the StudyIn this study, we demonstrate for the first time that microenvironment Cav3.2 contributes to GBM progression and growth by regulating neuronal and glial processes. Our findings highlight the importance of T-type calcium channels in the microenvironment as well as the tumor and provides preclinically relevant data for the use of mibefradil to inhibit GBM growth in combination with standard of care therapies.

cancer biology↗

bioRxiv2023

Purinergic P2Y2 Receptor-Induced Activation of Endothelial TRPV4 Channels Mediates Lung Ischemia-Reperfusion Injury

Lung ischemia-reperfusion injury (IRI), characterized by inflammation, vascular permeability, and lung edema, is the major cause of primary graft dysfunction after lung transplantation. We recently reported that endothelial cell (EC) TRPV4 channels play a central role in lung edema and dysfunction after IR. However, the cellular mechanisms for lung IR-induced activation of endothelial TRPV4 channels are unknown. In a left-lung hilar ligation model of IRI in mice, we found that lung IR increases the efflux of extracellular ATP (eATP) through pannexin 1 (Panx1) channels at the EC membrane. Elevated eATP activated elementary Ca2+ influx signals through endothelial TRPV4 channels through purinergic P2Y2 receptor (P2Y2R) signaling. P2Y2R-dependent activation of TRPV4 channels was also observed in human and mouse pulmonary microvascular endothelium in ex vivo and in vitro surrogate models of lung IR. Endothelium-specific deletion of P2Y2R, TRPV4, and Panx1 in mice had substantial protective effects against lung IR-induced activation of endothelial TRPV4 channels, lung edema, inflammation, and dysfunction. These results identify endothelial P2Y2R as a novel mediator of lung edema, inflammation, and dysfunction after IR, and show that disruption of endothelial Panx1-P2Y2R-TRPV4 signaling pathway could represent a promising therapeutic strategy for preventing lung IRI after transplantation.

physiology↗

bioRxiv2022

Polarized localization of phosphatidylserine in endothelium regulates Kir2.1

In the resistance artery endothelium, we show phosphatidylserine (PS) localizes to a specific subpopulation of myoendothelial junctions (MEJs), signaling microdomains that regulate vasodilation. In silico data has implied PS may compete with PIP2 binding on Kir2.1, a channel involved in vasodilatory signaling. We found 83.33% of Kir2.1-MEJs also contained PS, possibly indicating an interaction where PS regulates Kir2.1. Electrophysiology experiments on HEK cells demonstrate PS blocks PIP2 activation of Kir2.1, and addition of exogenous PS blocks PIP2-mediated Kir2.1 vasodilation in resistance arteries. Using a mouse model lacking canonical MEJs in resistance arteries (Elnfl/fl/Cdh5-Cre), PS localization in endothelium was disrupted and PIP2 activation of Kir2.1 was significantly increased. Taken together, our data suggests PS enrichment to MEJs inhibits PIP2-mediated activation of Kir2.1 to tightly regulate changes in arterial diameter, and demonstrates the intracellular lipid localization within endothelium is an important determinant of vascular function.

physiology↗

bioRxiv2022

FHL5 controls vascular disease-associated gene programs in smooth muscle cells

BackgroundGenome-wide association studies (GWAS) have identified hundreds of loci associated with common vascular diseases such as coronary artery disease (CAD), myocardial infarction (MI), and hypertension. However, the lack of mechanistic insights for a majority of these loci limits translation of these findings into the clinic. Among these loci with unknown functions is UFL1-FHL5 (chr6q16.1), a locus that reached genome-wide significance in a recent CAD/MI GWAS meta-analysis. In addition to CAD/MI, UFL1-FHL5 is also implicated to coronary calcium, intracranial aneurysm, and migraine risk, consistent with the widespread pleiotropy observed among other GWAS loci. MethodsWe apply a multimodal approach leveraging statistical fine-mapping, epigenomic profiling, and imaging of human coronary artery tissues to implicate Four-and-a-half LIM domain 5 (FHL5) as the top candidate causal gene. We unravel the molecular mechanisms of the cross-phenotype genetic associations through in vitro functional analyses and epigenomic profiling experiments. ResultsWe prioritized FHL5 as the top candidate causal gene at the UFL1-FHL5 locus through eQTL colocalization methods. FHL5 gene expression was enriched in the SMC and pericyte population in human artery tissues with coexpression network analyses supporting a functional role in regulating SMC contraction. Unexpectedly, under procalcifying conditions, FHL5 overexpression promoted vascular calcification and dysregulated processes related to extracellular matrix organization and calcium handling. Lastly, by mapping FHL5 binding sites and inferring FHL5 target gene function using artery tissue gene regulatory network analyses, we highlight regulatory interactions between FHL5 and downstream CAD/MI loci, such as FOXL1 and FN1 that have roles in vascular remodeling. ConclusionTaken together, these studies provide mechanistic insights into the pleiotropic genetic associations of UFL1-FHL5. We show that FHL5 mediates vascular disease risk through transcriptional regulation of downstream vascular remodeling loci. These trans-acting mechanisms may account for a portion of the heritable risk for complex vascular diseases.

genomics↗

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↗

bioRxiv2021

Endothelial alpha globin is a nitrite reductase

Small artery vasodilation in response to hypoxia is essential for matching oxygen supply to tissue oxygen demand. One source of hypoxic dilation via nitric oxide (NO) signaling is nitrite reduction by erythrocytic hemoglobin (2{beta}2). However, the alpha subunit of hemoglobin is also expressed in resistance artery endothelium and localized to myoendothelial junctions, a subcellular domain that contacts underlying vascular smooth muscle cells. We hypothesized that nitrite reduction mediated by endothelial alpha globin may occur at myoendothelial junctions to regulate hypoxic vasodilation. To test this concept, we created two novel mouse strains: one lacking alpha globin specifically in endothelium (EC Hba1{Delta}/{Delta}) and one where alpha globin is mutated such that its inhibitory association with endothelial NO synthase (eNOS) is prevented (Hba1WT/{Delta}36-39). In EC Hba1{Delta}/{Delta} or Hba1WT/{Delta}36-39 mice hemoglobin levels, hematocrit and erythrocyte counts were unchanged from littermate controls. Loss of the full alpha globin protein from the endothelium in the EC Hba1{Delta}/{Delta} model was associated with decreased exercise capacity and decreased intracellular nitrite utilization in hypoxic conditions. These effects were not seen in Hba1WT/{Delta}36-39 animals. Hypoxia induced vasodilation was decreased by 60% in isolated thoracodorsal arteries from EC Hba1{Delta}/{Delta}, while infusion of erythrocytes only partially rescued the dilatory response. Lastly, unlike other models where blood pressure is decreased, EC Hba1{Delta}/{Delta} blood pressure was not altered in response to hypoxia. Overall, we conclude that alpha globin in the resistance artery endothelium can act as a nitrite reductase to provide a local vasodilatory response to hypoxia.

physiology↗