Publications by authors named "Nina Wettschureck"

63 Publications

Myofibroblast YAP/TAZ is dispensable for liver fibrosis in mice.

J Hepatol 2021 Mar 3. Epub 2021 Mar 3.

Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Key Laboratory of Environment and Genes Related to Diseases, Xi'an, China; Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhep.2021.02.026DOI Listing
March 2021

Adipocyte Piezo1 mediates obesogenic adipogenesis through the FGF1/FGFR1 signaling pathway in mice.

Nat Commun 2020 05 8;11(1):2303. Epub 2020 May 8.

Max Planck Institute for Heart and Lung Research, Department of Pharmacology, Ludwigstr. 43, 61231, Bad Nauheim, Germany.

White adipose tissue (WAT) expansion in obesity occurs through enlargement of preexisting adipocytes (hypertrophy) and through formation of new adipocytes (adipogenesis). Adipogenesis results in WAT hyperplasia, smaller adipocytes and a metabolically more favourable form of obesity. How obesogenic WAT hyperplasia is induced remains, however, poorly understood. Here, we show that the mechanosensitive cationic channel Piezo1 mediates diet-induced adipogenesis. Mice lacking Piezo1 in mature adipocytes demonstrated defective differentiation of preadipocyte into mature adipocytes when fed a high fat diet (HFD) resulting in larger adipocytes, increased WAT inflammation and reduced insulin sensitivity. Opening of Piezo1 in mature adipocytes causes the release of the adipogenic fibroblast growth factor 1 (FGF1), which induces adipocyte precursor differentiation through activation of the FGF-receptor-1. These data identify a central feed-back mechanism by which mature adipocytes control adipogenesis during the development of obesity and suggest Piezo1-mediated adipocyte mechano-signalling as a mechanism to modulate obesity and its metabolic consequences.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-16026-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211025PMC
May 2020

Knockout mouse models reveal the contributions of G protein subunits to complement C5a receptor-mediated chemotaxis.

J Biol Chem 2020 05 24;295(22):7726-7742. Epub 2020 Apr 24.

Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Münster, Germany

G protein-coupled receptor signaling is required for the navigation of immune cells along chemoattractant gradients. However, chemoattractant receptors may couple to more than one type of heterotrimeric G protein, each of which consists of a Gα, Gβ, and Gγ subunit, making it difficult to delineate the critical signaling pathways. Here, we used knockout mouse models and time-lapse microscopy to elucidate Gα and Gβ subunits contributing to complement C5a receptor-mediated chemotaxis. Complement C5a-mediated chemokinesis and chemotaxis were almost completely abolished in macrophages lacking (encoding Gα), consistent with a reduced leukocyte recruitment previously observed in mice, whereas cells lacking (Gα) exhibited only a slight decrease in cell velocity. Surprisingly, C5a-induced Ca transients and lamellipodial membrane spreading were persistent in macrophages. Macrophages lacking both (Gα) and (Gα) or both (Gα) and (Gα) had essentially normal chemotaxis, Ca signaling, and cell spreading, except /-deficient macrophages had increased cell velocity and elongated trailing ends. Moreover, /-deficient cells did not respond to purinergic receptor P2Y stimulation. Genetic deletion of (Gα) virtually abolished C5a-induced Ca transients, but chemotaxis and cell spreading were preserved. Homozygous (Gβ) deletion was lethal, but mice lacking (Gβ) were viable. macrophages exhibited robust Ca transients and cell spreading, albeit decreased cell velocity and impaired chemotaxis. In summary, complement C5a-mediated chemotaxis requires Gα and Gβ, but not Ca signaling, and membrane protrusive activity is promoted by G proteins that deplete phosphatidylinositol 4,5-bisphosphate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.RA119.011984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261795PMC
May 2020

Orphan G Protein-Coupled Receptor GPRC5B Controls Smooth Muscle Contractility and Differentiation by Inhibiting Prostacyclin Receptor Signaling.

Circulation 2020 04 16;141(14):1168-1183. Epub 2020 Jan 16.

Department of Pharmacology (J.C., R.C., R.L., H.K., W.Z., S.T., S.O., N.W.), Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.

Background: G protein-coupled receptors are important regulators of contractility and differentiation in vascular smooth muscle cells (SMCs), but the specific function of SMC-expressed orphan G protein-coupled receptor class C group 5 member B (GPRC5B) is unclear.

Methods: We studied the role of GPRC5B in the regulation of contractility and dedifferentiation in human and murine SMCs in vitro and in iSM--KO (tamoxifen-inducible, SMC-specific knockout) mice under conditions of arterial hypertension and atherosclerosis in vivo.

Results: Mesenteric arteries from SMC-specific -KOs showed ex vivo significantly enhanced prostacyclin receptor (IP)-dependent relaxation, whereas responses to other relaxant or contractile factors were normal. In vitro, knockdown of GPRC5B in human aortic SMCs resulted in increased IP-dependent cAMP production and consecutive facilitation of SMC relaxation. In line with this facilitation of IP-mediated relaxation, iSM--KO mice were protected from arterial hypertension, and this protective effect was abrogated by IP antagonists. Mechanistically, we show that knockdown of GPRC5B increased the membrane localization of IP both in vitro and in vivo and that GPRC5B, but not other G protein-coupled receptors, physically interacts with IP. Last, we show that enhanced IP signaling in GPRC5B-deficient SMCs not only facilitates relaxation but also prevents dedifferentiation during atherosclerosis development, resulting in reduced plaque load and increased differentiation of SMCs in the fibrous cap.

Conclusions: Taken together, our data show that GPRC5B regulates vascular SMC tone and differentiation by negatively regulating IP signaling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCULATIONAHA.119.043703DOI Listing
April 2020

Protein Kinase N Promotes Stress-Induced Cardiac Dysfunction Through Phosphorylation of Myocardin-Related Transcription Factor A and Disruption of Its Interaction With Actin.

Circulation 2019 11 30;140(21):1737-1752. Epub 2019 Sep 30.

Departments of Cardiology (T.S., M.T., K. Kato, T.T., S.E., S.I., Y.M., Y.Y., T.Y., K.U., T.O, H.I., Y.S., Y.K.B., T.M.), Nagoya University School of Medicine, Japan.

Background: Heart failure is a complex syndrome that results from structural or functional impairment of ventricular filling or blood ejection. Protein phosphorylation is a major and essential intracellular mechanism that mediates various cellular processes in cardiomyocytes in response to extracellular and intracellular signals. The RHOA-associated protein kinase (ROCK/Rho-kinase), an effector regulated by the small GTPase RHOA, causes pathological phosphorylation of proteins, resulting in cardiovascular diseases. RHOA also activates protein kinase N (PKN); however, the role of PKN in cardiovascular diseases remains unclear.

Methods: To explore the role of PKNs in heart failure, we generated tamoxifen-inducible, cardiomyocyte-specific PKN1- and PKN2-knockout mice by intercrossing the αMHC-CreERT2 line with and mice and applied a mouse model of transverse aortic constriction- and angiotensin II-induced heart failure. To identify a novel substrate of PKNs, we incubated GST-tagged myocardin-related transcription factor A (MRTFA) with recombinant GST-PKN-catalytic domain or GST-ROCK-catalytic domain in the presence of radiolabeled ATP and detected radioactive GST-MRTFA as phosphorylated MRTFA.

Results: We demonstrated that RHOA activates 2 members of the PKN family of proteins, PKN1 and PKN2, in cardiomyocytes of mice with cardiac dysfunction. Cardiomyocyte-specific deletion of the genes encoding and (cmc-PKN1/2 DKO) did not affect basal heart function but protected mice from pressure overload- and angiotensin II-induced cardiac dysfunction. Furthermore, we identified MRTFA as a novel substrate of PKN1 and PKN2 and found that MRTFA phosphorylation by PKN was considerably more effective than that by ROCK in vitro. We confirmed that endogenous MRTFA phosphorylation in the heart was induced by pressure overload- and angiotensin II-induced cardiac dysfunction in wild-type mice, whereas cmc-PKN1/2 DKO mice suppressed transverse aortic constriction- and angiotensin II-induced phosphorylation of MRTFA. Although RHOA-mediated actin polymerization accelerated MRTFA-induced gene transcription, PKN1 and PKN2 inhibited the interaction of MRTFA with globular actin by phosphorylating MRTFA, causing increased serum response factor-mediated expression of cardiac hypertrophy- and fibrosis-associated genes.

Conclusions: Our results indicate that PKN1 and PKN2 activation causes cardiac dysfunction and is involved in the transition to heart failure, thus providing unique targets for therapeutic intervention for heart failure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCULATIONAHA.119.041019DOI Listing
November 2019

Myogenic vasoconstriction requires G/G and LARG to maintain local and systemic vascular resistance.

Elife 2019 09 24;8. Epub 2019 Sep 24.

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.

Myogenic vasoconstriction is an autoregulatory function of small arteries. Recently, G-protein-coupled receptors have been involved in myogenic vasoconstriction, but the downstream signalling mechanisms and the in-vivo-function of this myogenic autoregulation are poorly understood. Here, we show that small arteries from mice with smooth muscle-specific loss of G/G or the Rho guanine nucleotide exchange factor ARHGEF12 have lost myogenic vasoconstriction. This defect was accompanied by loss of RhoA activation, while vessels showed normal increases in intracellular [Ca]. In the absence of myogenic vasoconstriction, perfusion of peripheral organs was increased, systemic vascular resistance was reduced and cardiac output and left ventricular mass were increased. In addition, animals with defective myogenic vasoconstriction showed aggravated hypotension in response to endotoxin. We conclude that G/G- and Rho-mediated signaling plays a key role in myogenic vasoconstriction and that myogenic tone is required to maintain local and systemic vascular resistance under physiological and pathological condition.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.49374DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777979PMC
September 2019

Shear stress-induced endothelial adrenomedullin signaling regulates vascular tone and blood pressure.

J Clin Invest 2019 06 17;129(7):2775-2791. Epub 2019 Jun 17.

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI123825DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6597232PMC
June 2019

Passing the Vascular Barrier: Endothelial Signaling Processes Controlling Extravasation.

Physiol Rev 2019 07;99(3):1467-1525

Department of Pharmacology, Max Planck Institute for Heart and Lung Research , Bad Nauheim , Germany ; and Centre for Molecular Medicine, Medical Faculty, J.W. Goethe University Frankfurt , Frankfurt , Germany.

A central function of the vascular endothelium is to serve as a barrier between the blood and the surrounding tissue of the body. At the same time, solutes and cells have to pass the endothelium to leave or to enter the bloodstream to maintain homeostasis. Under pathological conditions, for example, inflammation, permeability for fluid and cells is largely increased in the affected area, thereby facilitating host defense. To appropriately function as a regulated permeability filter, the endothelium uses various mechanisms to allow solutes and cells to pass the endothelial layer. These include transcellular and paracellular pathways of which the latter requires remodeling of intercellular junctions for its regulation. This review provides an overview on endothelial barrier regulation and focuses on the endothelial signaling mechanisms controlling the opening and closing of paracellular pathways for solutes and cells such as leukocytes and metastasizing tumor cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/physrev.00037.2018DOI Listing
July 2019

Piezo1 and G/G promote endothelial inflammation depending on flow pattern and integrin activation.

J Exp Med 2018 10 7;215(10):2655-2672. Epub 2018 Sep 7.

Max Planck Institute for Heart and Lung Research, Department of Pharmacology, Bad Nauheim, Germany

The vascular endothelium is constantly exposed to mechanical forces, including fluid shear stress exerted by the flowing blood. Endothelial cells can sense different flow patterns and convert the mechanical signal of laminar flow into atheroprotective signals, including eNOS activation, whereas disturbed flow in atheroprone areas induces inflammatory signaling, including NF-κB activation. How endothelial cells distinguish different flow patterns is poorly understood. Here we show that both laminar and disturbed flow activate the same initial pathway involving the mechanosensitive cation channel Piezo1, the purinergic P2Y receptor, and G/G-mediated signaling. However, only disturbed flow leads to Piezo1- and G/G-mediated integrin activation resulting in focal adhesion kinase-dependent NF-κB activation. Mice with induced endothelium-specific deficiency of Piezo1 or Gα/Gα show reduced integrin activation, inflammatory signaling, and progression of atherosclerosis in atheroprone areas. Our data identify critical steps in endothelial mechanotransduction, which distinguish flow pattern-dependent activation of atheroprotective and atherogenic endothelial signaling and suggest novel therapeutic strategies to treat inflammatory vascular disorders such as atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1084/jem.20180483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6170174PMC
October 2018

Adiponectin release and insulin receptor targeting share trans-Golgi-dependent endosomal trafficking routes.

Mol Metab 2018 02 22;8:167-179. Epub 2017 Nov 22.

Department of Experimental Diabetology, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), 14558 Nuthetal, Germany; German Center for Diabetes Research, München-Neuherberg, 85764 Neuherberg, Germany. Electronic address:

Objective: Intracellular vesicle trafficking maintains cellular structures and functions. The assembly of cargo-laden vesicles at the trans-Golgi network is initiated by the ARF family of small GTPases. Here, we demonstrate the role of the trans-Golgi localized monomeric GTPase ARFRP1 in endosomal-mediated vesicle trafficking of mature adipocytes.

Methods: Control (Arfrp1) and inducible fat-specific Arfrp1 knockout (Arfrp1) mice were metabolically characterized. In vitro experiments on mature 3T3-L1 cells and primary mouse adipocytes were conducted to validate the impact of ARFRP1 on localization of adiponectin and the insulin receptor. Finally, secretion and transferrin-based uptake and recycling assays were performed with HeLa and HeLa M-C1 cells.

Results: We identified the ARFRP1-based sorting machinery to be involved in vesicle trafficking relying on the endosomal compartment for cell surface delivery. Secretion of adiponectin from fat depots was selectively reduced in Arfrp1 mice, and Arfrp1-depleted 3T3-L1 adipocytes revealed an accumulation of adiponectin in Rab11-positive endosomes. Plasma adiponectin deficiency of Arfrp1 mice resulted in deteriorated hepatic insulin sensitivity, increased gluconeogenesis and elevated fasting blood glucose levels. Additionally, the insulin receptor, undergoing endocytic recycling after ligand binding, was less abundant at the plasma membrane of adipocytes lacking Arfrp1. This had detrimental effects on adipose insulin signaling, followed by insufficient suppression of basal lipolytic activity and impaired adipose tissue expansion.

Conclusions: Our findings suggest that adiponectin secretion and insulin receptor surface targeting utilize the same post-Golgi trafficking pathways that are essential for an appropriate systemic insulin sensitivity and glucose homeostasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.molmet.2017.11.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985030PMC
February 2018

Members of Bitter Taste Receptor Cluster Are Expressed in the Epithelium of Murine Airways and Other Non-gustatory Tissues.

Front Physiol 2017 30;8:849. Epub 2017 Oct 30.

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.

The mouse bitter taste receptors Tas2r143, Tas2r135, and Tas2r126 are encoded by genes that cluster on chromosome 6 and have been suggested to be expressed under common regulatory elements. Previous studies indicated that the cluster is expressed in the heart, but other organs had not been systematically analyzed. In order to investigate the expression of this bitter taste receptor gene cluster in non-gustatory tissues, we generated a BAC (bacterial artificial chromosome) based transgenic mouse line, expressing CreERT2 under the control of the promoter. After crossing this line with a mouse line expressing EGFP after Cre-mediated recombination, we were able to validate the -CreERT2 transgenic mouse line and monitor the expression of . EGFP-positive cells, indicating expression of members of the cluster, were found in about 47% of taste buds, and could also be found in several other organs. A population of EGFP-positive cells was identified in thymic epithelial cells, in the lamina propria of the intestine and in vascular smooth muscle cells of cardiac blood vessels. EGFP-positive cells were also identified in the epithelium of organs readily exposed to pathogens including lower airways, the gastrointestinal tract, urethra, vagina, and cervix. With respect to the function of cells expressing this bitter taste receptor cluster, RNA-seq analysis in EGFP-positive cells isolated from the epithelium of trachea and stomach showed expression of genes related to innate immunity. These data further support the concept that bitter taste receptors serve functions outside the gustatory system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphys.2017.00849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5670347PMC
October 2017

Adipocyte cannabinoid receptor CB1 regulates energy homeostasis and alternatively activated macrophages.

J Clin Invest 2017 Nov 16;127(11):4148-4162. Epub 2017 Oct 16.

Institute of Physiological Chemistry, University Medical Center of Johannes Gutenberg University of Mainz, Mainz, Germany.

Dysregulated adipocyte physiology leads to imbalanced energy storage, obesity, and associated diseases, imposing a costly burden on current health care. Cannabinoid receptor type-1 (CB1) plays a crucial role in controlling energy metabolism through central and peripheral mechanisms. In this work, adipocyte-specific inducible deletion of the CB1 gene (Ati-CB1-KO) was sufficient to protect adult mice from diet-induced obesity and associated metabolic alterations and to reverse the phenotype in already obese mice. Compared with controls, Ati-CB1-KO mice showed decreased body weight, reduced total adiposity, improved insulin sensitivity, enhanced energy expenditure, and fat depot-specific cellular remodeling toward lowered energy storage capacity and browning of white adipocytes. These changes were associated with an increase in alternatively activated macrophages concomitant with enhanced sympathetic tone in adipose tissue. Remarkably, these alterations preceded the appearance of differences in body weight, highlighting the causal relation between the loss of CB1 and the triggering of metabolic reprogramming in adipose tissues. Finally, the lean phenotype of Ati-CB1-KO mice and the increase in alternatively activated macrophages in adipose tissue were also present at thermoneutral conditions. Our data provide compelling evidence for a crosstalk among adipocytes, immune cells, and the sympathetic nervous system (SNS), wherein CB1 plays a key regulatory role.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI83626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663356PMC
November 2017

Dual action by fumaric acid esters synergistically reduces adhesion to human endothelium.

Mult Scler 2018 12 6;24(14):1871-1882. Epub 2017 Oct 6.

Department of Neurology, University of Münster, Münster, Germany.

Objective: Dimethyl fumarate (DMF) is prescribed against relapsing-remitting multiple sclerosis (MS). Here, we investigated the effects of DMF and monomethyl fumarate (MMF), its metabolite in vivo, at the (inflamed) blood-brain barrier (BBB).

Methods: Effects of fumaric acid esters were analyzed using primary human brain-derived microvascular endothelial cells (HBMECs) in combination with peripheral blood mononuclear cells (PBMCs) derived from DMF-treated MS patients.

Results: MMF-binding to brain endothelium cells leads to activation of nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2)-induced downregulation of vascular cell adhesion molecule 1 (VCAM-1). This might be mediated via the G-protein-coupled receptor (GPCR) hydroxycarboxylic acid receptor 2 (HCA), a known molecular target of MMF, as we could demonstrate its expression and regulation on HBMECs. DMF treatment in vivo led to a strongly reduced expression of VCAM-1's ligand very late antigen 4 (VLA-4) by selectively reducing integrin high-expressing memory T cells of MS patients, potentially due to inhibition of their maturation by reduced trans-localization of NFκB.

Conclusion: DMF-mediated VCAM-1 downregulation on the endothelial side and reduction in T cells with a migratory phenotype on the lymphocyte side result in a synergistic reduction in T-cell adhesion to activated endothelium and, therefore, to reduced BBB transmigration in the setting of MS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1352458517735189DOI Listing
December 2018

Single-cell profiling reveals GPCR heterogeneity and functional patterning during neuroinflammation.

JCI Insight 2017 Aug 3;2(15). Epub 2017 Aug 3.

Department of Pharmacology.

GPCR expression was intensively studied in bulk cDNA of leukocyte populations, but limited data are available with respect to expression in individual cells. Here, we show a microfluidic-based single-cell GPCR expression analysis in primary T cells, myeloid cells, and endothelial cells under naive conditions and during experimental autoimmune encephalomyelitis, the mouse model of multiple sclerosis. We found that neuroinflammation induces characteristic changes in GPCR heterogeneity and patterning, and we identify various functionally relevant subgroups with specific GPCR profiles among spinal cord-infiltrating CD4 T cells, macrophages, microglia, or endothelial cells. Using GPCRs CXCR4, S1P1, and LPHN2 as examples, we show how this information can be used to develop new strategies for the functional modulation of Th17 cells and activated endothelial cells. Taken together, single-cell GPCR expression analysis identifies functionally relevant subpopulations with specific GPCR repertoires and provides a basis for the development of new therapeutic strategies in immune disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/jci.insight.95063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5543912PMC
August 2017

Corticotropin releasing hormone receptor 2 exacerbates chronic cardiac dysfunction.

J Exp Med 2017 Jul 26;214(7):1877-1888. Epub 2017 May 26.

Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan.

Heart failure occurs when the heart is unable to effectively pump blood and maintain tissue perfusion. Despite numerous therapeutic advancements over previous decades, the prognosis of patients with chronic heart failure remains poor, emphasizing the need to identify additional pathophysiological factors. Here, we show that corticotropin releasing hormone receptor 2 (Crhr2) is a G protein-coupled receptor highly expressed in cardiomyocytes and continuous infusion of the Crhr2 agonist, urocortin 2 (Ucn2), reduced left ventricular ejection fraction in mice. Moreover, plasma Ucn2 levels were 7.5-fold higher in patients with heart failure compared to those in healthy controls. Additionally, cardiomyocyte-specific deletion of Crhr2 protected mice from pressure overload-induced cardiac dysfunction. Mice treated with a Crhr2 antagonist lost maladaptive 3'-5'-cyclic adenosine monophosphate (cAMP)-dependent signaling and did not develop heart failure in response to overload. Collectively, our results indicate that constitutive Crhr2 activation causes cardiac dysfunction and suggests that Crhr2 blockade is a promising therapeutic strategy for patients with chronic heart failure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1084/jem.20161924DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5502432PMC
July 2017

EBI2 Is Highly Expressed in Multiple Sclerosis Lesions and Promotes Early CNS Migration of Encephalitogenic CD4 T Cells.

Cell Rep 2017 01;18(5):1270-1284

Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany. Electronic address:

Arrival of encephalitogenic T cells at inflammatory foci represents a critical step in development of experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. EBI2 and its ligand, 7α,25-OHC, direct immune cell localization in secondary lymphoid organs. CH25H and CYP7B1 hydroxylate cholesterol to 7α,25-OHC. During EAE, we found increased expression of CH25H by microglia and CYP7B1 by CNS-infiltrating immune cells elevating the ligand concentration in the CNS. Two critical pro-inflammatory cytokines, interleukin-23 (IL-23) and interleukin-1 beta (IL-1β), maintained expression of EBI2 in differentiating Th17 cells. In line with this, EBI2 enhanced early migration of encephalitogenic T cells into the CNS in a transfer EAE model. Nonetheless, EBI2 was dispensable in active EAE. Human Th17 cells do also express EBI2, and EBI2 expressing cells are abundant within multiple sclerosis (MS) white matter lesions. These findings implicate EBI2 as a mediator of CNS autoimmunity and describe mechanistically its contribution to the migration of autoreactive T cells into inflamed organs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.celrep.2017.01.020DOI Listing
January 2017

Endothelial cation channel PIEZO1 controls blood pressure by mediating flow-induced ATP release.

J Clin Invest 2016 12 31;126(12):4527-4536. Epub 2016 Oct 31.

Arterial blood pressure is controlled by vasodilatory factors such as nitric oxide (NO) that are released from the endothelium under the influence of fluid shear stress exerted by flowing blood. Flow-induced endothelial release of ATP and subsequent activation of Gq/G11-coupled purinergic P2Y2 receptors have been shown to mediate fluid shear stress-induced stimulation of NO formation. However, the mechanism by which fluid shear stress initiates these processes is unclear. Here, we have shown that the endothelial mechanosensitive cation channel PIEZO1 is required for flow-induced ATP release and subsequent P2Y2/Gq/G11-mediated activation of downstream signaling that results in phosphorylation and activation of AKT and endothelial NOS. We also demonstrated that PIEZO1-dependent ATP release is mediated in part by pannexin channels. The PIEZO1 activator Yoda1 mimicked the effect of fluid shear stress on endothelial cells and induced vasorelaxation in a PIEZO1-dependent manner. Furthermore, mice with induced endothelium-specific PIEZO1 deficiency lost the ability to induce NO formation and vasodilation in response to flow and consequently developed hypertension. Together, our data demonstrate that PIEZO1 is required for the regulation of NO formation, vascular tone, and blood pressure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI87343DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5127677PMC
December 2016

Increased apoptosis and browning of TAK1-deficient adipocytes protects against obesity.

JCI Insight 2016 05 19;1(7):e81175. Epub 2016 May 19.

Department of Pharmacology and.

Obesity is an increasing health problem worldwide, and nonsurgical strategies to treat obesity have remained rather inefficient. We here show that acute loss of TGF-β-activated kinase 1 (TAK1) in adipocytes results in an increased rate of apoptotic adipocyte death and increased numbers of M2 macrophages in white adipose tissue. Mice with adipocyte-specific TAK1 deficiency have reduced adipocyte numbers and are resistant to obesity induced by a high-fat diet or leptin deficiency. In addition, adipocyte-specific TAK1-deficient mice under a high-fat diet showed increased energy expenditure, which was accompanied by enhanced expression of the uncoupling protein UCP1. Interestingly, acute induction of adipocyte-specific TAK1 deficiency in mice already under a high-fat diet was able to stop further weight gain and improved glucose tolerance. Thus, loss of TAK1 in adipocytes reduces the total number of adipocytes, increases browning of white adipose tissue, and may be an attractive strategy to treat obesity, obesity-dependent diabetes, and other associated complications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/jci.insight.81175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5033847PMC
May 2016

Lineage tracing of cells involved in atherosclerosis.

Atherosclerosis 2016 08 11;251:445-453. Epub 2016 Jun 11.

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; Medical Faculty, Goethe University Frankfurt, Germany.

Background And Aims: Despite the clinical importance of atherosclerosis, the origin of cells within atherosclerotic plaques is not fully understood. Due to the lack of a definitive lineage-tracing strategy, previous studies have provided controversial results about the origin of cells expressing smooth muscle and macrophage markers in atherosclerosis. We here aim to identify the origin of vascular smooth muscle (SM) cells and macrophages within atherosclerosis lesions.

Methods: We combined a genetic fate mapping approach with single cell expression analysis in a murine model of atherosclerosis.

Results: We found that 16% of CD68-positive plaque macrophage-like cells were derived from mature SM cells and not from myeloid sources, whereas 31% of αSMA-positive smooth muscle-like cells in plaques were not SM-derived. Further analysis at the single cell level showed that SM-derived CD68(+) cells expressed higher levels of inflammatory markers such as cyclooxygenase 2 (Ptgs2, p = 0.02), and vascular cell adhesion molecule (Vcam1, p = 0.05), as well as increased mRNA levels of genes related to matrix synthesis such as Col1a2 (p = 0.01) and Fn1 (p = 0.04), than non SM-derived CD68(+) cells.

Conclusions: These results demonstrate that smooth muscle cells within atherosclerotic lesions can switch to a macrophage-like phenotype characterized by higher expression of inflammatory and synthetic markers genes that may further contribute to plaque progression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.atherosclerosis.2016.06.012DOI Listing
August 2016

Targeted Ablation of Periostin-Expressing Activated Fibroblasts Prevents Adverse Cardiac Remodeling in Mice.

Circ Res 2016 06 2;118(12):1906-17. Epub 2016 May 2.

From the Department of Pharmacology (H.K., C.Y.N., J.C., S.O., N.W.), Bioinformatics Facility (J.B., M.L.), Nuclear Magnetic Resonance Imaging Facility (A.W.), and Mass Spectrometry Group (A.P., S.H.), Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (M.T.); Department of Pediatrics, Indiana University School of Medicine, Indianapolis (S.J.C.); Department of Cardiology, Kerckhoff Heart and Thorax Center, Bad Nauheim, Germany (H.M., C.T.); and Medical Faculty, J.W. Goethe University Frankfurt, Frankfurt, Germany (S.O., N.W.).

Rationale: Activated cardiac fibroblasts (CF) are crucial players in the cardiac damage response; excess fibrosis, however, may result in myocardial stiffening and heart failure development. Inhibition of activated CF has been suggested as a therapeutic strategy in cardiac disease, but whether this truly improves cardiac function is unclear.

Objective: To study the effect of CF ablation on cardiac remodeling.

Methods And Results: We characterized subgroups of murine CF by single-cell expression analysis and identified periostin as the marker showing the highest correlation to an activated CF phenotype. We generated bacterial artificial chromosome-transgenic mice allowing tamoxifen-inducible Cre expression in periostin-positive cells as well as their diphtheria toxin-mediated ablation. In the healthy heart, periostin expression was restricted to valvular fibroblasts; ablation of this population did not affect cardiac function. After chronic angiotensin II exposure, ablation of activated CF resulted in significantly reduced cardiac fibrosis and improved cardiac function. After myocardial infarction, ablation of periostin-expressing CF resulted in reduced fibrosis without compromising scar stability, and cardiac function was significantly improved. Single-cell transcriptional analysis revealed reduced CF activation but increased expression of prohypertrophic factors in cardiac macrophages and cardiomyocytes, resulting in localized cardiomyocyte hypertrophy.

Conclusions: Modulation of the activated CF population is a promising approach to prevent adverse cardiac remodeling in response to angiotensin II and after myocardial infarction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/CIRCRESAHA.116.308643DOI Listing
June 2016

GNA13 loss in germinal center B cells leads to impaired apoptosis and promotes lymphoma in vivo.

Blood 2016 06 17;127(22):2723-31. Epub 2016 Mar 17.

Duke Cancer Institute and Department of Medicine, Duke University Medical Center, Durham, NC; Duke Center for Genomic and Computational Biology, Duke University, Durham, NC;

GNA13 is the most frequently mutated gene in germinal center (GC)-derived B-cell lymphomas, including nearly a quarter of Burkitt lymphoma and GC-derived diffuse large B-cell lymphoma. These mutations occur in a pattern consistent with loss of function. We have modeled the GNA13-deficient state exclusively in GC B cells by crossing the Gna13 conditional knockout mouse strain with the GC-specific AID-Cre transgenic strain. AID-Cre(+) GNA13-deficient mice demonstrate disordered GC architecture and dark zone/light zone distribution in vivo, and demonstrate altered migration behavior, decreased levels of filamentous actin, and attenuated RhoA activity in vitro. We also found that GNA13-deficient mice have increased numbers of GC B cells that display impaired caspase-mediated cell death and increased frequency of somatic hypermutation in the immunoglobulin VH locus. Lastly, GNA13 deficiency, combined with conditional MYC transgene expression in mouse GC B cells, promotes lymphomagenesis. Thus, GNA13 loss is associated with GC B-cell persistence, in which impaired apoptosis and ongoing somatic hypermutation may lead to an increased risk of lymphoma development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood-2015-07-659938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4991089PMC
June 2016

S1P2/G12/13 Signaling Negatively Regulates Macrophage Activation and Indirectly Shapes the Atheroprotective B1-Cell Population.

Arterioscler Thromb Vasc Biol 2016 Jan 24;36(1):37-48. Epub 2015 Nov 24.

From the Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (M.G., D.T., K.T., J.A.J., K.K.S., N.W.); Pharmazentrum Frankfurt/ZAFES, Clinical Pharmacology (N.F.B., G.G.) and Centre for Molecular Medicine, Medical Faculty (N.W.), J.W. Goethe University Frankfurt, Frankfurt, Germany; and Department of Laboratory Medicine, Medical University of Vienna and Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria (C.J.B.).

Objectives: Monocyte/macrophage recruitment and activation at vascular predilection sites plays a central role in the pathogenesis of atherosclerosis. Heterotrimeric G proteins of the G12/13 family have been implicated in the control of migration and inflammatory gene expression, but their function in myeloid cells, especially during atherogenesis, is unknown.

Approach And Results: Mice with myeloid-specific deficiency for G12/13 show reduced atherosclerosis with a clear shift to anti-inflammatory gene expression in aortal macrophages. These changes are because of neither altered monocyte/macrophage migration nor reduced activation of inflammatory gene expression; on the contrary, G12/13-deficient macrophages show an increased nuclear factor-κB-dependent gene expression in the resting state. Chronically increased inflammatory gene expression in resident peritoneal macrophages results in myeloid-specific G12/13-deficient mice in an altered peritoneal micromilieu with secondary expansion of peritoneal B1 cells. Titers of B1-derived atheroprotective antibodies are increased, and adoptive transfer of peritoneal cells from mutant mice conveys atheroprotection to wild-type mice. With respect to the mechanism of G12/13-mediated transcriptional control, we identify an autocrine feedback loop that suppresses nuclear factor-κB-dependent gene expression through a signaling cascade involving sphingosine 1-phosphate receptor subtype 2, G12/13, and RhoA.

Conclusions: Together, these data show that selective inhibition of G12/13 signaling in macrophages can augment atheroprotective B-cell populations and ameliorate atherosclerosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/ATVBAHA.115.306066DOI Listing
January 2016

Age-dependent blood pressure elevation is due to increased vascular smooth muscle tone mediated by G-protein signalling.

Cardiovasc Res 2016 Jan 3;109(1):131-40. Epub 2015 Nov 3.

Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany Medical Faculty, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany

Aims: Arterial hypertension is a major risk factor for cardiovascular diseases. The kidney and its natriuretic function are in the centre of the prevailing models to explain the pathogenesis of hypertension; however, the mechanisms underlying blood pressure elevation remain unclear in most patients. Development of hypertension is strongly correlated with age, and this blood pressure increase typically accelerates in the fourth decade of life. The cause of age-dependent blood pressure elevation is poorly understood. This study aims to understand the role of procontractile G-protein-mediated signalling pathways in vascular smooth muscle in age-dependent hypertension.

Methods And Results: Similar to humans at mid-life, we observed in 1-year-old mice elevated blood pressure levels without any evidence for increased vessel stiffness, impaired renal function, or endocrine abnormalities. Hypertensive aged mice showed signs of endothelial dysfunction and had an increased vascular formation of reactive oxygen species (ROS) and elevated endothelial ET-1 expression. Age-dependent hypertension could be normalized by ETA receptor blockade, smooth muscle-specific inactivation of the gene encoding the ETA receptor, as well as by acute disruption of downstream signalling via induction of smooth muscle-specific Gα12/Gα13, Gαq/Gα11, or LARG deficiency using tamoxifen-inducible smooth muscle-specific conditional mouse knock-out models. Induction of smooth muscle-specific ETA receptor deficiency normalized the blood pressure in aged mice despite the continuous presence of signs of endothelial dysfunction.

Conclusion: Age-dependent blood pressure elevation is due to a highly reversible activation of procontractile signalling in vascular smooth muscle cells indicating that increased vascular tone can be a primary factor in the development of hypertension.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cvr/cvv249DOI Listing
January 2016

GnRH Neuron-Specific Ablation of Gαq/11 Results in Only Partial Inactivation of the Neuroendocrine-Reproductive Axis in Both Male and Female Mice: In Vivo Evidence for Kiss1r-Coupled Gαq/11-Independent GnRH Secretion.

J Neurosci 2015 Sep;35(37):12903-16

Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115.

Unlabelled: The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility and kisspeptin (KP) is a potent trigger of GnRH secretion from GnRH neurons. KP signals via KISS1R, a Gαq/11-coupled receptor, and mice bearing a global deletion of Kiss1r (Kiss1r(-/-)) or a GnRH neuron-specific deletion of Kiss1r (Kiss1r(d/d)) display hypogonadotropic hypogonadism and infertility. KISS1R also signals via β-arrestin, and in mice lacking β-arrestin-1 or -2, KP-triggered GnRH secretion is significantly diminished. Based on these findings, we hypothesized that ablation of Gαq/11 in GnRH neurons would diminish but not completely block KP-triggered GnRH secretion and that Gαq/11-independent GnRH secretion would be sufficient to maintain fertility. To test this, Gnaq (encodes Gαq) was selectively inactivated in the GnRH neurons of global Gna11 (encodes Gα11)-null mice by crossing Gnrh-Cre and Gnaq(fl/fl);Gna11(-/-) mice. Experimental Gnaq(fl/fl);Gna11(-/-);Gnrh-Cre (Gnaq(d/d)) and control Gnaq(fl/fl);Gna11(-/-) (Gnaq(fl/fl)) littermate mice were generated and subjected to reproductive profiling. This process revealed that testicular development and spermatogenesis, preputial separation, and anogenital distance in males and day of vaginal opening and of first estrus in females were significantly less affected in Gnaq(d/d) mice than in previously characterized Kiss1r(-/-) or Kiss1r(d/d) mice. Additionally, Gnaq(d/d) males were subfertile, and although Gnaq(d/d) females did not ovulate spontaneously, they responded efficiently to a single dose of gonadotropins. Finally, KP stimulation triggered a significant increase in gonadotropins and testosterone levels in Gnaq(d/d) mice. We therefore conclude that the milder reproductive phenotypes and maintained responsiveness to KP and gonadotropins reflect Gαq/11-independent GnRH secretion and activation of the neuroendocrine-reproductive axis in Gnaq(d/d) mice.

Significance Statement: The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility. Over the last decade, several studies have established that the KISS1 receptor, KISS1R, is a potent trigger of GnRH secretion and inactivation of KISS1R on the GnRH neuron results in infertility. While KISS1R is best understood as a Gαq/11-coupled receptor, we previously demonstrated that it could couple to and signal via non-Gαq/11-coupled pathways. The present study confirms these findings and, more importantly, while it establishes Gαq/11-coupled signaling as a major conduit of GnRH secretion, it also uncovers a significant role for non-Gαq/11-coupled signaling in potentiating reproductive development and function. This study further suggests that by augmenting signaling via these pathways, GnRH secretion can be enhanced to treat some forms of infertility.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.0041-15.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4571609PMC
September 2015

Endothelial Gαq/11 is required for VEGF-induced vascular permeability and angiogenesis.

Cardiovasc Res 2015 Oct 13;108(1):171-80. Epub 2015 Aug 13.

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany J.W. Goethe University Frankfurt, 60590 Frankfurt, Germany

Aims: VEGF A (VEGF-A) is a central regulator of pre- and postnatal vascular development. In vitro studies suggested that heterotrimeric G-proteins of the Gq/11 family contribute to VEGF receptor 2 (VEGFR2) signalling, but the mechanism and physiological relevance of this finding is unknown. The aim of this study is to understand the role of endothelial Gαq/11 in VEGF-dependent regulation of vascular permeability and angiogenesis.

Methods And Results: We show here that VEGF-A-induced signalling events, such as VEGFR2 autophosphorylation, calcium mobilization, or phosphorylation of Src and Cdh5, were reduced in Gαq/11-deficient endothelial cells (ECs), resulting in impaired VEGF-dependent barrier opening, tube formation, and proliferation. Agonists at Gq/11-coupled receptors facilitated VEGF-A-induced VEGFR2 autophosphorylation in a Gαq/11-dependent manner, thereby enhancing downstream VEGFR2 signalling. In vivo, EC-specific Gαq/11- and Gαq-deficient mice showed reduced VEGF-induced fluid extravasation, and retinal angiogenesis was significantly impaired. Gαq-deficient ECs showed reduced proliferation, Cdh5 phosphorylation, and fluid extravasation, whereas apoptosis was increased.

Conclusion: Gαq/11 critically contributes to VEGF-A-dependent permeability control and angiogenic behaviour in vitro and in vivo.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/cvr/cvv216DOI Listing
October 2015

P2Y₂ and Gq/G₁₁ control blood pressure by mediating endothelial mechanotransduction.

J Clin Invest 2015 Aug 13;125(8):3077-86. Epub 2015 Jul 13.

Elevated blood pressure is a key risk factor for developing cardiovascular diseases. Blood pressure is largely determined by vasodilatory mediators, such as nitric oxide (NO), that are released from the endothelium in response to fluid shear stress exerted by the flowing blood. Previous work has identified several mechanotransduction signaling processes that are involved in fluid shear stress-induced endothelial effects, but how fluid shear stress initiates the response is poorly understood. Here, we evaluated human and bovine endothelial cells and found that the purinergic receptor P2Y2 and the G proteins Gq/G11 mediate fluid shear stress-induced endothelial responses, including [Ca2+]i transients, activation of the endothelial NO synthase (eNOS), phosphorylation of PECAM-1 and VEGFR-2, as well as activation of SRC and AKT. In response to fluid shear stress, endothelial cells released ATP, which activates the purinergic P2Y2 receptor. Mice with induced endothelium-specific P2Y2 or Gq/G11 deficiency lacked flow-induced vasodilation and developed hypertension that was accompanied by reduced eNOS activation. Together, our data identify P2Y2 and Gq/G11 as a critical endothelial mechanosignaling pathway that is upstream of previously described mechanotransduction processes and demonstrate that P2Y2 and Gq/G11 are required for basal endothelial NO formation, vascular tone, and blood pressure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI81067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4563756PMC
August 2015

Hydroxycarboxylic acid receptor 2 mediates dimethyl fumarate's protective effect in EAE.

J Clin Invest 2014 May 1;124(5):2188-92. Epub 2014 Apr 1.

Taken orally, the drug dimethyl fumarate (DMF) has been shown to improve functional outcomes for patients with MS; however, it is unclear how DMF mediates a protective effect. DMF and, more so, its active metabolite, monomethyl fumarate, are known agonists of the hydroxycarboxylic acid receptor 2 (HCA₂), a G protein-coupled membrane receptor. Here, we evaluated the contribution of HCA₂ in mediating the protective effect afforded by DMF in EAE, a mouse model of MS. DMF treatment reduced neurological deficit, immune cell infiltration, and demyelination of the spinal cords in wild-type mice, but not in Hca2⁻/⁻ mice, indicating that HCA₂ is required for the therapeutic effect of DMF. In particular, DMF decreased the number of infiltrating neutrophils in a HCA₂-dependent manner, likely by interfering with neutrophil adhesion to endothelial cells and chemotaxis. Together, our data indicate that HCA₂ mediates the therapeutic effects of DMF in EAE. Furthermore, identification of HCA₂ as a molecular target may help to optimize MS therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI72151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001545PMC
May 2014

Transforming growth factor-β-activated kinase 1 regulates angiogenesis via AMP-activated protein kinase-α1 and redox balance in endothelial cells.

Arterioscler Thromb Vasc Biol 2013 Dec 26;33(12):2792-9. Epub 2013 Sep 26.

From the Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, Frankfurt, Germany and DZHK (German Centre for Cardiovascular Research) partner site Rhine-Main (N.Z., R.A.M., T.F., R.P., E.B., I.F., B.F.); and Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany (B.S., N.W.).

Objective: Transforming growth factor-β-activated kinase 1 (TAK1) is a mitogen-activated protein 3-kinase and an AMP-activated protein kinase (AMPK) kinase in some cell types. Although TAK1(-/-) mice display defects in developmental vasculogenesis, the role of TAK1 in endothelial cells has not been investigated in detail.

Approach And Results: TAK1 downregulation (small interfering RNA) in human endothelial cells attenuated proliferation without inducing apoptosis and diminished endothelial cell migration, as well as tube formation. Cytokine- and vascular endothelial growth factor (VEGF)-induced endothelial cell sprouting in a modified spheroid assay were abrogated by TAK1 downregulation. Moreover, VEGF-induced endothelial sprouting was impaired in aortic rings from mice lacking TAK1 in endothelial cells (TAK(ΔEC)). TAK1 inhibition and downregulation also inhibited VEGF-stimulated phosphorylation of several kinases, including AMPK. Proteomic analyses revealed that superoxide dismutase 2 (SOD2) expression was reduced in TAK1-deficient endothelial cells, resulting in attenuated hydrogen peroxide production but increased mitochondrial superoxide production. Endothelial cell SOD2 expression was also attenuated by AMPK inhibition and in endothelial cells from AMPKα1(-/-) mice but was unaffected by inhibitors of c-Jun N-terminal kinase, p38, extracellular signal-regulated kinase 1/2, or phosphatidylinositol 3-kinase/Akt. Moreover, the impaired endothelial sprouting from TAK(ΔEC) aortic rings was abrogated in the presence of polyethylene glycol-SOD, and tube formation was normalized by the overexpression of SOD2. A similar rescue of angiogenesis was observed in polyethylene glycol-SOD-treated aortic rings from mice with endothelial cell-specific deletion of the AMPKα1.

Conclusions: These results establish TAK1 as an AMPKα1 kinase that regulates vascular endothelial growth factor-induced and cytokine-induced angiogenesis by modulating SOD2 expression and the superoxide anion:hydrogen peroxide balance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/ATVBAHA.113.301848DOI Listing
December 2013

Response to Harper et al.

Cancer Cell 2013 Sep;24(3):288

Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ccr.2013.08.015DOI Listing
September 2013

Platelet-derived nucleotides promote tumor-cell transendothelial migration and metastasis via P2Y2 receptor.

Cancer Cell 2013 Jul 27;24(1):130-7. Epub 2013 Jun 27.

Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany.

Tumor cells can activate platelets, which in turn facilitate tumor cell survival and dissemination. The exact mechanisms by which platelets promote metastasis have remained unclear. Here, we show that adenine nucleotides released from tumor cell-activated platelets induce opening of the endothelial barrier to allow transendothelial migration of tumor cells and thereby promote cancer cell extravasation. We identified the endothelial P2Y2 receptor, which is activated by ATP, as the primary mediator of this effect. Mice deficient in P2Y2 or lacking ATP secretion from platelets show strongly reduced tumor cell metastasis. These findings demonstrate a mechanism by which platelets promote cancer cell metastasis and suggest the P2Y2 receptor and its endothelial downstream signaling mechanisms as a target for antimetastatic therapies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ccr.2013.05.008DOI Listing
July 2013