Hypertension is a primary risk factor for cardiovascular diseases including myocardial infarction and stroke. Major determinants of blood pressure are vasodilatory factors such as nitric oxide (NO) released from the endothelium under the influence of fluid shear stress exerted by the flowing blood. Several endothelial signaling processes mediating fluid shear stress–induced formation and release of vasodilatory factors have been described. It is, however, still poorly understood how fluid shear stress induces these endothelial responses. Here we show that the endothelial mechanosensitive cation channel PIEZO1 mediated fluid shear stress–induced release of adrenomedullin, which in turn activated its Gs-coupled receptor. The subsequent increase in cAMP levels promoted the phosphorylation of endothelial NO synthase (eNOS) at serine 633 through protein kinase A (PKA), leading to the activation of the enzyme. This Gs/PKA-mediated pathway synergized with the AKT-mediated pathways leading to eNOS phosphorylation at serine 1177. Mice with endothelium-specific deficiency of adrenomedullin, the adrenomedullin receptor, or Gαs showed reduced flow-induced eNOS activation and vasodilation and developed hypertension. Our data identify fluid shear stress–induced PIEZO1 activation as a central regulator of endothelial adrenomedullin release and establish the adrenomedullin receptor and subsequent Gs-mediated formation of cAMP as a critical endothelial mechanosignaling pathway regulating basal endothelial NO formation, vascular tone, and blood pressure.
Andras Iring, Young-June Jin, Julián Albarrán-Juárez, Mauro Siragusa, ShengPeng Wang, Péter T. Dancs, Akiko Nakayama, Sarah Tonack, Min Chen, Carsten Künne, Anna M. Sokol, Stefan Günther, Alfredo Martínez, Ingrid Fleming, Nina Wettschureck, Johannes Graumann, Lee S. Weinstein, Stefan Offermanns
Combined germline and somatic second hit inactivating mutations of the RASA1 gene, which encodes a negative regulator of the Ras signaling pathway, cause blood and lymphatic vascular lesions in the human autosomal dominant vascular disorder capillary malformation-arteriovenous malformation (CM-AVM). How RASA1 mutations in endothelial cells (EC) result in vascular lesions in CM-AVM is unknown. Here, using different murine models of RASA1-deficiency, we found that RASA1 was essential for the survival of EC during developmental angiogenesis in which primitive vascular plexuses are remodeled into hierarchical vascular networks. RASA1 was required for EC survival during developmental angiogenesis because it was necessary for export of collagen IV from EC and deposition in vascular basement membranes. In the absence of RASA1, dysregulated Ras mitogen-activated protein kinase (MAPK) signal transduction in EC resulted in impaired folding of collagen IV and its retention in the endoplasmic reticulum (ER) leading to EC death. Remarkably, the chemical chaperone, 4-phenylbutyric acid, and small molecule inhibitors of MAPK and 2-oxoglutarate dependent collagen IV modifying enzymes rescued ER retention of collagen IV and EC apoptosis and resulted in normal developmental angiogenesis. These findings have important implications with regards an understanding of the molecular pathogenesis of CM-AVM and possible means of treatment.
Di Chen, Joyce Teng, Paula North, Philip E. Lapinski, Philip D. King
Elevated blood glucose (hyperglycemia) is a hallmark metabolic abnormality in diabetes. Hyperglycemia is associated with protein kinase A (PKA)-mediated stimulation of L-type Ca2+ channels in arterial myocytes resulting in increased vasoconstriction. However, the mechanisms by which glucose activates PKA remain unclear. Here, we showed that elevating extracellular glucose stimulates cAMP production in arterial myocytes, and that this was specifically dependent on adenylyl cyclase 5 (AC5) activity. Super-resolution imaging suggested nanometer proximity between subpopulations of AC5 and the L-type Ca2+ channel pore-forming subunit CaV1.2. In vitro, in silico, ex vivo and in vivo experiments revealed that this close association is critical for stimulation of L-type Ca2+ channels in arterial myocytes and increased myogenic tone upon acute hyperglycemia. This pathway supported the increase in L-type Ca2+ channel activity and myogenic tone in two animal models of diabetes. Our collective findings demonstrate a unique role for AC5 in PKA-dependent modulation of L-type Ca2+ channel activity and vascular reactivity during acute hyperglycemia and diabetes.
Arsalan U. Syed, Gopireddy R. Reddy, Debapriya Ghosh, Maria Paz Prada, Matthew A. Nystoriak, Stefano Morotti, Eleonora Grandi, Padmini Sirish, Nipavan Chiamvimonvat, Johannes W. Hell, Luis F. Santana, Yang K. Xiang, Madeline Nieves-Cintrón, Manuel F. Navedo
Deep vein thrombosis (DVT), caused by alterations in venous homeostasis is the third most common cause of cardiovascular mortality; however, key molecular determinants in venous thrombosis have not been fully elucidated. Several lines of evidence indicate that DVT occurs at the intersection of dysregulated inflammation and coagulation. The enzyme ectonucleoside tri(di)phosphohydrolase (ENTPD1, also known as CD39) is a vascular ecto-apyrase on the surface of leukocytes and the endothelium that inhibits intravascular inflammation and thrombosis by hydrolysis of phosphodiester bonds from nucleotides released by activated cells. Here, we evaluated the contribution of CD39 to venous thrombosis in a restricted-flow model of murine inferior vena cava stenosis. CD39-deficiency conferred a >2-fold increase in venous thrombogenesis, characterized by increased leukocyte engagement, neutrophil extracellular trap formation, fibrin, and local activation of tissue factor in the thrombotic milieu. This was orchestrated by increased phosphorylation of the p65 subunit of NFκB, activation of the NLRP3 inflammasome, and interleukin-1β (IL-1β) release in CD39-deficient mice. Substantiating these findings, an IL-1β-neutralizing antibody attenuated the thrombosis risk in CD39-deficient mice. These data demonstrate that IL-1β is a key accelerant of venous thrombo-inflammation, which can be suppressed by CD39. CD39 inhibits in vivo crosstalk between inflammation and coagulation pathways, and is a critical vascular checkpoint in venous thrombosis.
Vinita Yadav, Liguo Chi, Raymond Zhao, Benjamin Tourdot, Srilakshmi Yalavarthi, Benjamin N. Jacobs, Alison Banka, Hui Liao, Sharon Koonse, Anuli C. Anyanwu, Scott Visovatti, Michael Holinstat, J. Michelle Kahlenberg, Jason S. Knight, David J. Pinsky, Yogendra Kanthi
The lung is a specialized barrier organ that must tightly regulate interstitial fluid clearance and prevent infection in order to maintain effective gas exchange. Lymphatic vessels are important for these functions in other organs, but their roles in the lung have not been fully defined. In the present study, we addressed how the lymphatic vasculature participates in lung homeostasis. Studies using mice carrying a lymphatic reporter allele revealeded that, in contrast to other organs, lung lymphatic collecting vessels lack smooth muscle cells entirely, suggesting that forward lymph flow is highly dependent on movement and changes in pressure associated with respiration. Functional studies using CLEC2-deficient mice in which lymph flow is impaired due to loss of lympho-venous hemostasis or using inducible lung-specific ablation of lymphatic endothelial cells in a lung transplant model revealeded that loss of lymphatic function leads to an inflammatory state characterized by the formation of tertiary lymphoid organs (TLOs). In addition, impaired lymphatic flow in mice resulteds in hypoxia and features of lung injury that resemble emphysema. These findings reveal both a lung-specific mechanism of lymphatic physiology and a lung-specific consequence of lymphatic dysfunction that may contribute to chronic lung diseases that arise in association with TLO formation.
Hasina Outtz Reed, Liqing Wang, Jarrod Sonett, Mei Chen, Jisheng Yang, Larry Li, Petra Aradi, Zoltán Jakus, Jeanine M. D'Armiento, Wayne W. Hancock, Mark L. Kahn
Mice selectively expressing PPARγ dominant negative mutation in vascular smooth muscle exhibit RhoBTB1-deficiency and hypertension. Our rationale was to employ genetic complementation to uncover the mechanism of action of RhoBTB1 in vascular smooth muscle. Inducible smooth muscle-specific restoration of RhoBTB1 fully corrected the hypertension and arterial stiffness by improving vasodilator function. Notably, the cardiovascular protection occurred despite preservation of increased agonist-mediated contraction and RhoA/Rho kinase activity, suggesting RhoBTB1 selectively controls vasodilation. RhoBTB1 augmented the cGMP response to nitric oxide by restraining the activity of phosphodiesterase 5 (PDE5) by acting as a substrate adaptor delivering PDE5 to the Cullin-3 E3 Ring ubiquitin ligase complex for ubiquitination inhibiting PDE5. Angiotensin-II infusion also caused RhoBTB1-deficiency and hypertension which was prevented by smooth muscle specific RhoBTB1 restoration. We conclude that RhoBTB1 protected from hypertension, vascular smooth muscle dysfunction, and arterial stiffness in at least two models of hypertension.
Masashi Mukohda, Shi Fang, Jing Wu, Larry N. Agbor, Anand R. Nair, Stella-Rita C. Ibeawuchi, Chunyan Hu, Xuebo Liu, Ko-Ting Lu, Deng-Fu Guo, Deborah R. Davis, Henry L. Keen, Frederick W. Quelle, Curt D. Sigmund
In tumors, extravascular fibrin forms provisional scaffolds for endothelial cell (EC) growth and motility during angiogenesis. We report that fibrin-mediated angiogenesis was inhibited and tumor growth delayed following postnatal deletion of Tgfbr2 in the endothelium of Cdh5-CreERT2 Tgfbr2fl/fl mice (Tgfbr2iECKO mice). ECs from Tgfbr2iECKO mice failed to upregulate the fibrinolysis inhibitor plasminogen activator inhibitor 1 (Serpine1, also known as PAI-1), due in part to uncoupled TGF-β–mediated suppression of miR-30c. Bypassing TGF-β signaling with vascular tropic nanoparticles that deliver miR-30c antagomiRs promoted PAI-1–dependent tumor growth and increased fibrin abundance, whereas miR-30c mimics inhibited tumor growth and promoted vascular-directed fibrinolysis in vivo. Using single-cell RNA-Seq and a NanoString miRNA array, we also found that subtypes of ECs in tumors showed spectrums of Serpine1 and miR-30c expression levels, suggesting functional diversity in ECs at the level of individual cells; indeed, fresh EC isolates from lung and mammary tumor models had differential abilities to degrade fibrin and launch new vessel sprouts, a finding that was linked to their inverse expression patterns of miR-30c and Serpine1 (i.e., miR-30chi Serpine1lo ECs were poorly angiogenic and miR-30clo Serpine1hi ECs were highly angiogenic). Thus, by balancing Serpine1 expression in ECs downstream of TGF-β, miR-30c functions as a tumor suppressor in the tumor microenvironment through its ability to promote fibrin degradation and inhibit blood vessel formation.
James V. McCann, Lin Xiao, Dae Joong Kim, Omar F. Khan, Piotr S. Kowalski, Daniel G. Anderson, Chad V. Pecot, Salma H. Azam, Joel S. Parker, Yihsuan S. Tsai, Alisa S. Wolberg, Stephen D. Turner, Kohei Tatsumi, Nigel Mackman, Andrew C. Dudley
Upon arterial injury, endothelial denudation leads to platelet activation, and delivery of multiple agents (e.g. TXA2, PDGF) promoting VSMC dedifferentiation, and proliferation, in injury repair (intimal hyperplasia). Resolution of vessel injury repair, and prevention of excessive repair (switching VSMC back to a differentiated quiescent state) is a poorly understood process. We now report that internalization of activated platelets by VSMCs promotes resolution of arterial injury by switching on VSMC quiescence. Ex vivo and in vivo studies using lineage tracing reporter mice (PF4-Cre x mTmG) demonstrated uptake of green platelets by red vascular smooth muscle cells upon arterial wire injury. Genome-wide miRNA sequencing of VSMCs co-cultured with activated platelets identified significant increases in platelet-derived miR-223. miR-223 appears to directly target PDGFRβ (in VSMCs) reversing the injury-induced dedifferentiation. Upon arterial injury platelet miR-223 knockout mice exhibit increased intimal hyperplasia, whereas miR-223 mimics reduced intimal hyperplasia. Diabetic mice with reduced expression of miR-223, exhibited enhanced VSMC dedifferentiation, proliferation, and increased intimal hyperplasia. Horizontal transfer of platelet-derived miRNAs into VSMCs provide a novel mechanism for regulating VSMC phenotypic switching. Platelets thus play a dual role in vascular injury repair, initiating an immediate repair process, and concurrently, a delayed process to prevent excessive repair.
Zhi Zeng, Luoxing Xia, Xuejiao Fan, Allison C. Ostriker, Timur Yarovinsky, Meiling Su, Yuan Zhang, Xiangwen Peng, Xie Yi, Lei Pi, Xiaoqiong Gu, Sookja Kim Chung, Kathleen A. Martin, Renjing Liu, John Hwa, Wai Ho Tang
Local flow patterns determine the uneven distribution of atherosclerotic lesions. This research aims to elucidate the mechanism of regulation of nuclear translocation of Yes-associated protein (YAP) under oscillatory shear stress (OSS) in the atheroprone phenotype of endothelial cells (ECs). We report here that OSS led to tyrosine phosphorylation and strong, continuous nuclear translocation of YAP in ECs that is dependent on integrin α5β1 activation. YAP overexpression in ECs blunted the anti-atheroprone effect of an integrin-α5β1 blocking peptide (ATN161) in Apoe-/- mice. Activation of integrin α5β1 induced tyrosine, but not serine, phosphorylation of YAP in ECs. Blockage of integrin α5β1 with ATN161 abolished the phosphorylation of YAP at Y357 induced by OSS. Mechanistic studies showed that c-Abl inhibitor attenuated the integrin α5β1-induced YAP tyrosine phosphorylation. Furthermore, the phosphorylation of c-Abl and YAPY357 was significantly increased in ECs in atherosclerotic vessels of mice and in human plaques vs. normal vessels. Finally, bosutinib, a tyrosine kinase inhibitor, markedly reduced the level of YAPY357 and the development of atherosclerosis in Apoe-/- mice. The c-Abl/YAPY357 pathway serves as a mechanism for the activation of integrin α5β1 and the atherogenic phenotype of ECs in response to OSS, and provides a potential therapeutic strategy for atherogenesis.
Bochuan Li, Jinlong He, Huizhen Lv, Yajin Liu, Xue Lv, Chenghu Zhang, Yi Zhu, Ding Ai
The aortic root is the predominant site for development of aneurysm caused by heterozygous loss-of-function mutations in positive effectors of the transforming growth factor-β (TGF-β) pathway. Using a mouse model of Loeys-Dietz syndrome (LDS) that carries a heterozygous kinase-inactivating mutation in TGF-β receptor I, we found that the effects of this mutation depend on the lineage of origin of vascular smooth muscle cells (VSMCs). Secondary heart field–derived (SHF-derived), but not neighboring cardiac neural crest–derived (CNC-derived), VSMCs showed impaired Smad2/3 activation in response to TGF-β, increased expression of angiotensin II (AngII) type 1 receptor (Agtr1a), enhanced responsiveness to AngII, and higher expression of TGF-β ligands. The preserved TGF-β signaling potential in CNC-derived VSMCs associated, in vivo, with increased Smad2/3 phosphorylation. CNC-, but not SHF-specific, deletion of Smad2 preserved aortic wall architecture and reduced aortic dilation in this mouse model of LDS. Taken together, these data suggest that aortic root aneurysm predisposition in this LDS mouse model depends both on defective Smad signaling in SHF-derived VSMCs and excessive Smad signaling in CNC-derived VSMCs. This work highlights the importance of considering the regional microenvironment and specifically lineage-dependent variation in the vulnerability to mutations in the development and testing of pathogenic models for aortic aneurysm.
Elena Gallo MacFarlane, Sarah J. Parker, Joseph Y. Shin, Shira G. Ziegler, Tyler J. Creamer, Rustam Bagirzadeh, Djahida Bedja, Yichun Chen, Juan F. Calderon, Katherine Weissler, Pamela A. Frischmeyer-Guerrerio, Mark E. Lindsay, Jennifer P. Habashi, Harry C. Dietz