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Jerry B. Lingrel - One of the best experts on this subject based on the ideXlab platform.
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reduced levels of micrornas mir 124a and mir 150 are associated with increased proinflammatory mediator expression in kruppel like factor 2 KLF2 deficient macrophages
Journal of Biological Chemistry, 2014Co-Authors: Palanikumar Manoharan, Joshua E Basford, Robyn Pilcherroberts, Jonathan C Neumann, David Y Hui, Jerry B. LingrelAbstract:Previous studies have shown that the myeloid-specific deficiency of the transcription factor Kruppel-like factor 2 (KLF2) accelerates atherosclerosis in hypercholesterolemic Ldlr−/− mice due to the enhanced adhesion of myeloid cells to activated endothelial cells in the vessel wall. This study revealed elevated basal inflammation with elevated plasma levels of Ccl2, Ccl4, Ccl5, and Ccl11 in the myeloid-specific KLF2 knock-out (myeKLF2−/−) mice. Peritoneal macrophages isolated from myeKLF2−/− mice showed increased mRNA levels of several inflammatory mediators, including Ccl2, Ccl5, Ccl7, Cox-2, Cxcl1, and IL-6. In contrast, the levels of two microRNAs, miR-124a and miR-150, were lower in KLF2−/− macrophages compared with KLF2+/+ macrophages. Additional studies showed a direct inverse relationship between miR-124a levels with Ccl2 expression, with anti-miR-124a increasing Ccl2 mRNA levels in KLF2+/+ macrophages, whereas the restoration of miR-124a levels in KLF2−/− macrophages significantly reduced Ccl2 mRNA expression. Likewise, the inverse relationship was observed between miR-150 levels and Cxcl1 expression in KLF2+/+ and KLF2−/− mice. Moreover, miR150 likely regulates the miR124a expression and thus augments expression of inflammatory mediators in myeKLF2−/− macrophages. This study documented that the transcription factor KLF2 modulates inflammatory chemokine production via regulation of microRNA expression levels in immune cells.
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KLF2 transcription factor modulates blood vessel maturation through smooth muscle cell migration
Journal of Biological Chemistry, 2008Co-Authors: Cynthia S Bohanan, Jon C Neumann, Jerry B. LingrelAbstract:Vasculogenesis, angiogenesis, and maturation are three major phases of the development of blood vessels. Although many receptors required for blood vessel formation have been defined, the intracellular signal transduction pathways involved in vascular maturation remain unclear. KLF2–/– embryos fail to develop beyond 13.5 days because of a lack of blood vessel stabilization. The molecular mechanism of KLF2 function in embryonic vascular vessels is still largely unknown. Here we show a normal development pattern of endothelial cells in KLF2–/– embryos but a defect of smooth muscle cells at the dorsal side of the aorta. This phenotype results from arrested vascular maturation characterized by the failure of mural cells to migrate around endothelial cells. This migration defect is also observed when platelet-derived growth factor-B (PDGF) controlled migration is studied in murine embryonic fibroblast (MEF) cells from KLF2–/– animals. In addition, KLF2–/– MEFs exhibit a significant growth defect, indicating that KLF2 is required to maintain the viability of MEF cells. The PDGF signal is mediated through the Src signaling pathway, and a downstream target of KLF2 is sphingosine 1-phosphate receptor 1. These studies demonstrate that KLF2 is required for smooth muscle cell migration and elucidate a novel mechanism involving communication between PDGF and KLF2 in vascular maturation.
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eklf and KLF2 have compensatory roles in embryonic β globin gene expression and primitive erythropoiesis
Blood, 2007Co-Authors: Priyadarshi Basu, Jerry B. Lingrel, Wafaa Lemsaddek, Latasha C Redmond, Jack L Haar, Mohua Basu, Tina K. Lung, Thanh Giang Sargent, David C Williams, Joyce A LloydAbstract:The Kruppel-like C2/H2 zinc finger transcription factors (KLFs) control development and differentiation. Erythroid Kruppel-like factor (EKLF or KLF1) regulates adult β-globin gene expression and is necessary for normal definitive erythropoiesis. KLF2 is required for normal embryonic Ey- and βh1-, but not adult βglobin, gene expression in mice. Both EKLF and KLF2 play roles in primitive erythroid cell development. To investigate potential interactions between these genes, EKLF/KLF2 double-mutant embryos were analyzed. EKLF−/−KLF2−/− mice appear anemic at embryonic day 10.5 (E10.5) and die before E11.5, whereas single-knockout EKLF−/− or KLF2−/− embryos are grossly normal at E10.5 and die later than EKLF−/−KLF2−/− embryos. At E10.5, Ey- and βh1-globin mRNA is greatly reduced in EKLF−/−KLF2−/−, compared with EKLF−/− or KLF2−/− embryos, consistent with the observed anemia. Light and electron microscopic analyses of E9.5 EKLF−/−KLF2−/− yolk sacs, and cytospins, indicate that erythroid and endothelial cells are morphologically more abnormal than in either single knockout. EKLF−/−KLF2−/− erythroid cells are markedly irregularly shaped, suggesting membrane abnormalities. EKLF and KLF2 may have coordinate roles in a common progenitor to erythroid and endothelial cells. The data indicate that EKLF and KLF2 have redundant functions in embryonic β-like globin gene expression, primitive erythropoiesis, and endothelial development.
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kruppel like factor 2 regulates thymocyte and t cell migration
Nature, 2006Co-Authors: Corey M Carlson, Jerry B. Lingrel, Bart T Endrizzi, Jinghai Wu, Xiaojie Ding, Michael A Weinreich, Elizabeth R Walsh, Maqsood A Wani, Kristin A Hogquist, Stephen C JamesonAbstract:The transcription factor KLF2 has long been thought to play a critical role in controlling survival and quiescence of mature T cells, since KLF2-deficient T cells develop in the thymus but fail to populate peripheral lymph organs. A new study offers an alternative explanation for this phenotype, consistent with an entirely different function for KLF2 as a regulator of thymocyte and T-cell migration. Proteins of the KLF (Kruppel-like transcription factor) family are involved in many aspects of vertebrate development and are implicated in a number of disease states. This newly discovered role for KLF2 is similar to some other KLFs that are essential for terminal differentiation of various cell types. The transcription factor KLF2 has been thought to control survival of T lymphocytes, as KLF2-deficient T cells develop in the thymus, but fail to populate the peripheral lymphoid organs. But this report shows that the phenotype results from an unexpected role of KLF2 in regulating the expression of lymphocyte trafficking molecules. Mammalian Kruppel-like transcription factors are implicated in regulating terminal differentiation of several tissue types1,2,3. Deficiency in Kruppel-like factor (KLF) 2 (also known as LKLF) leads to a massive loss of the peripheral T-cell pool4, suggesting KLF2 regulates T-cell quiescence and survival4,5,6,7. Here we show, however, that KLF2 is essential for T-cell trafficking. KLF2-deficient (KLF2-/-) thymocytes show impaired expression of several receptors required for thymocyte emigration and peripheral trafficking, including the sphingosine-1-phosphate (S1P) receptor S1P1, CD62L and β7 integrin. Furthermore, KLF2 both binds and transactivates the promoter for S1P1—a receptor that is critical for thymocyte egress and recirculation through peripheral lymphoid organs. Our findings suggest that KLF2 serves to license mature T cells for trafficking from the thymus and recirculation through secondary lymphoid tissues.
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KLF2 is essential for primitive erythropoiesis and regulates the human and murine embryonic β like globin genes in vivo
Blood, 2005Co-Authors: Priyadarshi Basu, Jerry B. Lingrel, Maqsood A Wani, Jack L Haar, Karin M L Gaensler, Pamela E Morris, Joyce A LloydAbstract:The Kruppel-like factors (KLFs) are a family of C2/H2 zinc finger DNA-binding proteins that are important in controlling developmental programs. Erythroid Kruppel-like factor (EKLF or KLF1) positively regulates the β-globin gene in definitive erythroid cells. KLF2 (LKLF) is closely related to EKLF and is expressed in erythroid cells. KLF2-/- mice die between embryonic day 12.5 (E12.5) and E14.5, because of severe intraembryonic hemorrhaging. They also display growth retardation and anemia. We investigated the expression of the β-like globin genes in KLF2 knockout mice. Our results show that KLF2-/- mice have a significant reduction of murine embryonic Ey- and βh1-globin but not ζ-globin gene expression in the E10.5 yolk sac, compared with wild-type mice. The expression of the adult βmaj- and βmin-globin genes is unaffected in the fetal livers of E12.5 embryos. In mice carrying the entire human globin locus, KLF2 also regulates the expression of the human embryonic e-globin gene but not the adult β-globin gene, suggesting that this developmental-stage-specific role is evolutionarily conserved. KLF2 also plays a role in the maturation and/or stability of erythroid cells in the yolk sac. KLF2-/- embryos have a significantly increased number of primitive erythroid cells undergoing apoptotic cell death. (Blood. 2005;106: 2566-2571)
Anton J G Horrevoets - One of the best experts on this subject based on the ideXlab platform.
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KLF2 Primes the Antioxidant Transcription Factor Nrf2 for Activation in Endothelial Cells
2016Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective—Atheroprotective blood flow induces expression of anti-inflammatory Krüppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results—Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions—We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells. (Arterioscler Thromb Vasc Biol. 2008;28:1339-1346) Key Words: endothelium shear stress KLF2 oxidative stress Nrf
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KLF2 primes the antioxidant transcription factor nrf2 for activation in endothelial cells
Arteriosclerosis Thrombosis and Vascular Biology, 2008Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Seppo Ylaherttuala, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective— Atheroprotective blood flow induces expression of anti-inflammatory Kruppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results— Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions— We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells.
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KLF2 primes the antioxidant transcription factor nrf2 for activation in endothelial cells
Arteriosclerosis Thrombosis and Vascular Biology, 2008Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Seppo Ylaherttuala, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective— Atheroprotective blood flow induces expression of anti-inflammatory Kruppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results— Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions— We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells.
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shear stress sustains atheroprotective endothelial KLF2 expression more potently than statins through mrna stabilization
Cardiovascular Research, 2006Co-Authors: Johannes V Van Thienen, Hans Pannekoek, Joost O. Fledderus, Rob J Dekker, Jakub Rohlena, Gerben A Van Ijzendoorn, Neeltje A Kootstra, Anton J G HorrevoetsAbstract:Objective: The transcription factor KLF2 is considered an important mediator of the anti-inflammatory and anti-thrombotic properties of the endothelium. KLF2 is absent from low-shear, atherosclerosis-prone sites of the vascular tree but is induced by HMG-CoA reductase inhibitors (statins) in vitro. We studied KLF2 -dependent induction of important determinants of the atheroprotective status of the endothelium to determine whether pharmacological intervention, e.g. by statins, can potentially replace shear stress. Methods: Shear stress and statin effects in combination with TNF-α were determined in human umbilical vein endothelial cells by quantitative measurements of the steady-state levels and stability of mRNA for KLF2 and its downstream target genes thrombomodulin (TM) and endothelial nitric oxide synthase (eNOS). Results: We demonstrate that prolonged shear stress has a potential that is superior to that of statins to induce the KLF2 -dependent expression of eNOS and TM, especially in the presence of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). These effects can be attributed to the sustained stabilization of KLF2 mRNA by shear, leading to an increased KLF2 protein expression and concomitant strong induction of KLF2 downstream targets. The stabilization of KLF2 mRNA is demonstrated to be dependent on signaling involving phosphoinositide 3-kinase (PI3K). Conclusion: The stabilization of KLF2 steady-state levels, as induced by prolonged shear stress but not by statins, may be essential for sustaining the quiescent, atheroprotective status of the vascular endothelium under inflammatory conditions.
Guillermo Garciacardena - One of the best experts on this subject based on the ideXlab platform.
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KLF2 exerts antifibrotic and vasoprotective effects in cirrhotic rat livers behind the molecular mechanisms of statins
Gut, 2015Co-Authors: Giusi Marrone, Guillermo Garciacardena, Juan Carlos Garciapagan, Jaime Bosch, Raquel Maesodiaz, Juan G Abraldes, Jordi GraciasanchoAbstract:Objective In the liver, the transcription factor, Kruppel-like factor 2 (KLF2), is induced early during progression of cirrhosis to lessen the development of vascular dysfunction; nevertheless, its endogenous expression results insufficient to attenuate establishment of portal hypertension and aggravation of cirrhosis. Herein, we aimed to explore the effects and the underlying mechanisms of hepatic KLF2 overexpression in in vitro and in vivo models of liver cirrhosis. Design Activation phenotype was evaluated in human and rat cirrhotic hepatic stellate cells (HSC) treated with the pharmacological inductor of KLF2 simvastatin, with adenovirus codifying for this transcription factor (Ad-KLF2), or vehicle, in presence/absence of inhibitors of KLF2. Possible paracrine interactions between parenchymal and non-parenchymal cells overexpressing KLF2 were studied. Effects of in vivo hepatic KLF2 overexpression on liver fibrosis and systemic and hepatic haemodynamics were assessed in cirrhotic rats. Results KLF2 upregulation profoundly ameliorated HSC phenotype (reduced α-smooth muscle actin, procollagen I and oxidative stress) partly via the activation of the nuclear factor (NF)-E2-related factor 2 (Nrf2). Coculture experiments showed that improvement in HSC phenotype paracrinally ameliorated liver sinusoidal endothelial cells probably through a vascular endothelial growth factor-mediated mechanism. No paracrine interactions between hepatocytes and HSC were observed. Cirrhotic rats treated with simvastatin or Ad-KLF2 showed hepatic upregulation in the KLF2-Nrf2 pathway, deactivation of HSC and prominent reduction in liver fibrosis. Hepatic KLF2 overexpression was associated with lower portal pressure (–15%) due to both attenuations in the increased portal blood flow and hepatic vascular resistance, together with a significant improvement in hepatic endothelial dysfunction. Conclusions Exogenous hepatic KLF2 upregulation improves liver fibrosis, endothelial dysfunction and portal hypertension in cirrhosis.
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the transcription factor KLF2 mediates hepatic endothelial protection and paracrine endothelial stellate cell deactivation induced by statins
Journal of Hepatology, 2013Co-Authors: Giusi Marrone, Guillermo Garciacardena, Juan Carlos Garciapagan, Jaime Bosch, Lucia Russo, Eugenio Rosado, Diana Hide, Jorge GraciasanchoAbstract:Background & Aims Statins improve hepatic endothelial function and liver fibrosis in experimental models of cirrhosis, thus they have been proposed as therapeutic options to ameliorate portal hypertension syndrome. The transcription factor Kruppel-like factor 2 (KLF2) may be induced by statins in liver sinusoidal endothelial cells (SEC), orchestrating an efficient vasoprotective response. The present study aimed at characterizing whether KLF2 mediates statins-derived hepatic protection. Methods Expression of KLF2 and its vasoprotective target genes was determined in SEC freshly isolated from control or CCl 4 -cirrhotic rats treated with four different statins (atorvastatin, mevastatin, simvastatin, and lovastatin), in the presence of mevalonate (or vehicle), under static or controlled shear stress conditions. KLF2-derived vasoprotective transcriptional programs were analyzed in SEC transfected with siRNA for KLF2 or siRNA-control, and incubated with simvastatin. Paracrine effects of SEC highly-expressing KLF2 on the activation status of rat and human hepatic stellate cells (HSC) were evaluated. Results Statins administration to SEC induced significant upregulation of KLF2 expression. KLF2 upregulation was observed after 6h of treatment and was accompanied by induction of its vasoprotective programs. Simvastatin vasoprotection was inhibited in the presence of mevalonate, and was magnified in cells cultured under physiological shear stress conditions. Statin-dependent induction of vasoprotective genes was not observed when KLF2 expression was muted with siRNA. SEC overexpressing KLF2 induced quiescence of HSC through a KLF2–nitric oxide–guanylate cyclase-mediated paracrine mechanism. Conclusions Upregulation of hepatic endothelial KLF2-derived transcriptional programs by statins confers vasoprotection and stellate cells deactivation, reinforcing the therapeutic potential of these drugs for liver diseases that course with endothelial dysfunction.
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endothelial expression of transcription factor kruppel like factor 2 and its vasoprotective target genes in the normal and cirrhotic rat liver
Gut, 2011Co-Authors: Jorge Graciasancho, Guillermo Garciacardena, Lucia Russo, Hector Garciacaldero, Joan Carles Garciapagan, Jaime BoschAbstract:Objective The transcription factor Kruppel-like factor 2 (KLF2) modulates the expression of multiple endothelial vasoprotective genes. In the absence of KLF2, the endothelial phenotype becomes dysfunctional. To date, blood-derived shear stress is the main physiological stimulus identified to trigger and sustain endothelial KLF2 expression. Portal hypertension is a common complication of cirrhosis. Sinusoidal distortion and endothelial dysfunction play a significant role in its pathogenesis. This study aimed to assess whether abnormal intrahepatic haemodynamics in cirrhosis could modify KLF2 expression and consequently its downstream transcriptional programmes. Design Rats received carbon tetrachloride or vehicle for two (acute injury), six (early cirrhosis) and twelve weeks (advanced cirrhosis). Systemic and hepatic haemodynamic parameters were measured in vivo. Hepatic expression of KLF2 and its vasoprotective targets were determined. Additionally, KLF2 expression was determined in liver sections, in freshly-isolated hepatic endothelial cells, and in livers from simvastatin-treated cirrhotic animals. Results Cirrhotic livers have increased endothelial KLF2 expression compared with controls. KLF2 elevation, observed at six weeks of cirrhosis induction, was accompanied by a parallel increase in portal pressure and an increase in the expression of its target genes eNOS, thrombomodulin and CNP. Simvastatin administration further increased hepatic KLF2 and target genes expression. Conclusions This study shows an increase in the expression of the vasoprotective transcription factor KLF2 in the cirrhotic liver, accompanied by an activation of its downstream transcriptional programmes. These data suggest that the marked increase in KLF2 expression may represent an endothelial compensatory mechanism to improve the ongoing vascular dysfunction in the cirrhotic liver.
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defining the regulation of klf4 expression and its downstream transcriptional targets in vascular endothelial cells
Biochemical and Biophysical Research Communications, 2010Co-Authors: Guadalupe Villarreal, Yuzhi Zhang, Benjamin H Larman, Jorge Graciasancho, Andrew Koo, Guillermo GarciacardenaAbstract:The Kruppel-like factor 2 (KLF2) and Kruppel-like factor 4 (KLF4) transcription factors have recently been shown to act as critical regulators of endothelial homeostasis. While several insights have been made into the signaling mechanisms orchestrating endothelial KLF2 expression, those governing the expression of KLF4 in the vascular endothelium remain largely unknown. Here, we show that diverse vasoprotective stimuli including an atheroprotective shear stress waveform, simvastatin, and resveratrol induce the expression of KLF4 in cultured human endothelial cells. We further demonstrate that the induction of KLF4 by resveratrol and atheroprotective shear stress occurs via a MEK5/MEF2-dependent signaling pathway. Since MEK5 activation is also critical for the expression of KLF2, we assessed the individual contribution of KLF4 and KLF2 to the global transcriptional activity triggered by MEK5 activation. Genome-wide transcriptional profiling of endothelial cells overexpressing KLF4, KLF2, or constitutively active MEK5 revealed that 59.2% of the genes regulated by the activation of MEK5 were similarly controlled by either KLF2 or KLF4. Collectively, our data identify a significant degree of mechanistic and functional conservation between KLF2 and KLF4, and importantly, provide further insights into the complex regulatory networks governing endothelial vasoprotection.
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kruppel like factor 2 KLF2 regulates endothelial thrombotic function
Circulation Research, 2005Co-Authors: Zhiyong Lin, Ajay Kumar, Sucharita Senbanerjee, Kristine Staniszewski, Kush M Parmar, Douglas E Vaughan, Michael A Gimbrone, Viji Balasubramanian, Guillermo Garciacardena, Mukesh K. JainAbstract:The vascular endothelium maintains blood fluidity by inhibiting blood coagulation, inhibiting platelet aggregation, and promoting fibrinolysis. Endothelial cells lose these nonthrombogenic properties on exposure to proinflammatory stimuli. We recently identified the Kruppel-like factor KLF2 as a novel regulator of endothelial proinflammatory activation. Here it is found that KLF2 differentially regulates key factors involved in maintaining an antithrombotic endothelial surface. Overexpression of KLF2 strongly induced thrombomodulin (TM) and endothelial nitric oxide synthase (eNOS) expression and reduced plasminogen activator inhibitor-1 (PAI-1) expression. Furthermore, overexpression of KLF2 inhibited the cytokine-mediated induction of tissue factor (TF). In contrast, siRNA mediated knockdown of KLF2 reduced antithrombotic gene expression while inducing the expression of pro-coagulant factors. The functional importance of KLF2 was verified by in vitro clotting assays. By comparison to control infected cells, KLF2 overexpression increased blood clotting time as well as flow rates under basal and inflammatory conditions. In contrast, siRNA-mediated knockdown of KLF2 reduced blood clotting time and flow rates. These observations identify KLF2 as a novel transcriptional regulator of endothelial thrombotic function. The full text of this article is available online at http://circres.ahajournals.org.
Jaime Bosch - One of the best experts on this subject based on the ideXlab platform.
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cross talk between autophagy and KLF2 determines endothelial cell phenotype and microvascular function in acute liver injury
Journal of Hepatology, 2017Co-Authors: Sergi Guixemuntet, Fernanda Cristina De Mesquita, Sergi Vila, Virginia Hernandezgea, Carmen A Peralta, Juan Carlos Garciapagan, Jaime Bosch, Jordi GraciasanchoAbstract:Background & Aims The transcription factor Kruppel-like factor 2 (KLF2), inducible by simvastatin, confers endothelial vasoprotection. Considering recent data suggesting activation of autophagy by statins, we aimed to: 1) characterize the relationship between autophagy and KLF2 in the endothelium, 2) assess this relationship in acute liver injury (cold ischemia/reperfusion) and 3) study the effects of modulating KLF2-autophagy in vitro and in vivo . Methods Autophagic flux, the vasoprotective KLF2 pathway, cell viability and microvascular function were assessed in endothelial cells and in various pre-clinical models of acute liver injury (cold storage and warm reperfusion). Results Positive feedback between autophagy and KLF2 was observed in the endothelium: KLF2 inducers, pharmacological (statins, resveratrol, GGTI-298), biomechanical (shear stress) or genetic (adenovirus containing KLF2), caused endothelial KLF2 overexpression through a Rac1-rab7-autophagy dependent mechanism, both in the specialized liver sinusoidal endothelial cells (LSEC) and in human umbilical vein endothelial cells. In turn, KLF2 induction promoted further activation of autophagy. Cold ischemia blunted autophagic flux. Upon reperfusion, LSEC stored in University of Wisconsin solution did not reactivate autophagy, which resulted in autophagosome accumulation probably due to impairment in autophagosome-lysosome fusion, ultimately leading to increased cell death and microvascular dysfunction. Simvastatin pretreatment maintained autophagy (through the upregulation of rab7), resulting in increased KLF2, improved cell viability, and ameliorated hepatic damage and microvascular function. Conclusions We herein describe for the first time the complex autophagy-KLF2 relationship, modulating the phenotype and survival of the endothelium. These results help understanding the mechanisms of protection conferred by KLF2-inducers, such as simvastatin, in hepatic vascular disorders. Lay summary Autophagy and the transcription factor KLF2 share a common activation pathway in the endothelium, being able to regulate each other. Statins maintain microvascular function through the inhibition of Rac1, which consequently liberates Rab7, activates autophagy and increments the expression of KLF2.
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KLF2 exerts antifibrotic and vasoprotective effects in cirrhotic rat livers behind the molecular mechanisms of statins
Gut, 2015Co-Authors: Giusi Marrone, Guillermo Garciacardena, Juan Carlos Garciapagan, Jaime Bosch, Raquel Maesodiaz, Juan G Abraldes, Jordi GraciasanchoAbstract:Objective In the liver, the transcription factor, Kruppel-like factor 2 (KLF2), is induced early during progression of cirrhosis to lessen the development of vascular dysfunction; nevertheless, its endogenous expression results insufficient to attenuate establishment of portal hypertension and aggravation of cirrhosis. Herein, we aimed to explore the effects and the underlying mechanisms of hepatic KLF2 overexpression in in vitro and in vivo models of liver cirrhosis. Design Activation phenotype was evaluated in human and rat cirrhotic hepatic stellate cells (HSC) treated with the pharmacological inductor of KLF2 simvastatin, with adenovirus codifying for this transcription factor (Ad-KLF2), or vehicle, in presence/absence of inhibitors of KLF2. Possible paracrine interactions between parenchymal and non-parenchymal cells overexpressing KLF2 were studied. Effects of in vivo hepatic KLF2 overexpression on liver fibrosis and systemic and hepatic haemodynamics were assessed in cirrhotic rats. Results KLF2 upregulation profoundly ameliorated HSC phenotype (reduced α-smooth muscle actin, procollagen I and oxidative stress) partly via the activation of the nuclear factor (NF)-E2-related factor 2 (Nrf2). Coculture experiments showed that improvement in HSC phenotype paracrinally ameliorated liver sinusoidal endothelial cells probably through a vascular endothelial growth factor-mediated mechanism. No paracrine interactions between hepatocytes and HSC were observed. Cirrhotic rats treated with simvastatin or Ad-KLF2 showed hepatic upregulation in the KLF2-Nrf2 pathway, deactivation of HSC and prominent reduction in liver fibrosis. Hepatic KLF2 overexpression was associated with lower portal pressure (–15%) due to both attenuations in the increased portal blood flow and hepatic vascular resistance, together with a significant improvement in hepatic endothelial dysfunction. Conclusions Exogenous hepatic KLF2 upregulation improves liver fibrosis, endothelial dysfunction and portal hypertension in cirrhosis.
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the transcription factor KLF2 mediates hepatic endothelial protection and paracrine endothelial stellate cell deactivation induced by statins
Journal of Hepatology, 2013Co-Authors: Giusi Marrone, Guillermo Garciacardena, Juan Carlos Garciapagan, Jaime Bosch, Lucia Russo, Eugenio Rosado, Diana Hide, Jorge GraciasanchoAbstract:Background & Aims Statins improve hepatic endothelial function and liver fibrosis in experimental models of cirrhosis, thus they have been proposed as therapeutic options to ameliorate portal hypertension syndrome. The transcription factor Kruppel-like factor 2 (KLF2) may be induced by statins in liver sinusoidal endothelial cells (SEC), orchestrating an efficient vasoprotective response. The present study aimed at characterizing whether KLF2 mediates statins-derived hepatic protection. Methods Expression of KLF2 and its vasoprotective target genes was determined in SEC freshly isolated from control or CCl 4 -cirrhotic rats treated with four different statins (atorvastatin, mevastatin, simvastatin, and lovastatin), in the presence of mevalonate (or vehicle), under static or controlled shear stress conditions. KLF2-derived vasoprotective transcriptional programs were analyzed in SEC transfected with siRNA for KLF2 or siRNA-control, and incubated with simvastatin. Paracrine effects of SEC highly-expressing KLF2 on the activation status of rat and human hepatic stellate cells (HSC) were evaluated. Results Statins administration to SEC induced significant upregulation of KLF2 expression. KLF2 upregulation was observed after 6h of treatment and was accompanied by induction of its vasoprotective programs. Simvastatin vasoprotection was inhibited in the presence of mevalonate, and was magnified in cells cultured under physiological shear stress conditions. Statin-dependent induction of vasoprotective genes was not observed when KLF2 expression was muted with siRNA. SEC overexpressing KLF2 induced quiescence of HSC through a KLF2–nitric oxide–guanylate cyclase-mediated paracrine mechanism. Conclusions Upregulation of hepatic endothelial KLF2-derived transcriptional programs by statins confers vasoprotection and stellate cells deactivation, reinforcing the therapeutic potential of these drugs for liver diseases that course with endothelial dysfunction.
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endothelial expression of transcription factor kruppel like factor 2 and its vasoprotective target genes in the normal and cirrhotic rat liver
Gut, 2011Co-Authors: Jorge Graciasancho, Guillermo Garciacardena, Lucia Russo, Hector Garciacaldero, Joan Carles Garciapagan, Jaime BoschAbstract:Objective The transcription factor Kruppel-like factor 2 (KLF2) modulates the expression of multiple endothelial vasoprotective genes. In the absence of KLF2, the endothelial phenotype becomes dysfunctional. To date, blood-derived shear stress is the main physiological stimulus identified to trigger and sustain endothelial KLF2 expression. Portal hypertension is a common complication of cirrhosis. Sinusoidal distortion and endothelial dysfunction play a significant role in its pathogenesis. This study aimed to assess whether abnormal intrahepatic haemodynamics in cirrhosis could modify KLF2 expression and consequently its downstream transcriptional programmes. Design Rats received carbon tetrachloride or vehicle for two (acute injury), six (early cirrhosis) and twelve weeks (advanced cirrhosis). Systemic and hepatic haemodynamic parameters were measured in vivo. Hepatic expression of KLF2 and its vasoprotective targets were determined. Additionally, KLF2 expression was determined in liver sections, in freshly-isolated hepatic endothelial cells, and in livers from simvastatin-treated cirrhotic animals. Results Cirrhotic livers have increased endothelial KLF2 expression compared with controls. KLF2 elevation, observed at six weeks of cirrhosis induction, was accompanied by a parallel increase in portal pressure and an increase in the expression of its target genes eNOS, thrombomodulin and CNP. Simvastatin administration further increased hepatic KLF2 and target genes expression. Conclusions This study shows an increase in the expression of the vasoprotective transcription factor KLF2 in the cirrhotic liver, accompanied by an activation of its downstream transcriptional programmes. These data suggest that the marked increase in KLF2 expression may represent an endothelial compensatory mechanism to improve the ongoing vascular dysfunction in the cirrhotic liver.
Joost O. Fledderus - One of the best experts on this subject based on the ideXlab platform.
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KLF2 Primes the Antioxidant Transcription Factor Nrf2 for Activation in Endothelial Cells
2016Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective—Atheroprotective blood flow induces expression of anti-inflammatory Krüppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results—Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions—We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells. (Arterioscler Thromb Vasc Biol. 2008;28:1339-1346) Key Words: endothelium shear stress KLF2 oxidative stress Nrf
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KLF2 primes the antioxidant transcription factor nrf2 for activation in endothelial cells
Arteriosclerosis Thrombosis and Vascular Biology, 2008Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Seppo Ylaherttuala, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective— Atheroprotective blood flow induces expression of anti-inflammatory Kruppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results— Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions— We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells.
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KLF2 primes the antioxidant transcription factor nrf2 for activation in endothelial cells
Arteriosclerosis Thrombosis and Vascular Biology, 2008Co-Authors: Joost O. Fledderus, Oscar L Volger, H Hurttila, Anna-liisa Levonen, Reinier A Boon, Seppo Ylaherttuala, Hans Pannekoek, Anton J G HorrevoetsAbstract:Objective— Atheroprotective blood flow induces expression of anti-inflammatory Kruppel-like factor 2 (KLF2) and activates antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in vascular endothelium. Previously, we obtained KLF2-induced gene expression profiles in ECs, containing several Nrf2 target genes. Our aim was to investigate the role of KLF2 in shear stress–mediated activation of Nrf2 in human umbilical vein endothelial cells (HUVECs). Methods and Results— Expression of Nrf2 and its targets NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase (HO-1) was elevated by shear and KLF2. KLF2 knockdown showed that shear-induced expression of NQO1 but not Nrf2 was dependent on KLF2. KLF2 overexpression in absence of flow resulted in more efficient activation of Nrf2 by tert-butyl hydroquinone (tBHQ) through enhanced nuclear localization, and promoted expression of a large panel of Nrf2-dependent genes resulting in superior protection against oxidative stress. Comparison of shear-, KLF2-, and Nrf2-induced transcriptomes showed that the majority of shear-modulated gene sets is influenced by KLF2 or Nrf2. Conclusions— We report that KLF2 substantially enhances antioxidant activity of Nrf2 by increasing its nuclear localization and activation. The synergistic activity of these two transcription factors forms a major contribution to the shear stress–elicited transcriptome in endothelial cells.
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shear stress sustains atheroprotective endothelial KLF2 expression more potently than statins through mrna stabilization
Cardiovascular Research, 2006Co-Authors: Johannes V Van Thienen, Hans Pannekoek, Joost O. Fledderus, Rob J Dekker, Jakub Rohlena, Gerben A Van Ijzendoorn, Neeltje A Kootstra, Anton J G HorrevoetsAbstract:Objective: The transcription factor KLF2 is considered an important mediator of the anti-inflammatory and anti-thrombotic properties of the endothelium. KLF2 is absent from low-shear, atherosclerosis-prone sites of the vascular tree but is induced by HMG-CoA reductase inhibitors (statins) in vitro. We studied KLF2 -dependent induction of important determinants of the atheroprotective status of the endothelium to determine whether pharmacological intervention, e.g. by statins, can potentially replace shear stress. Methods: Shear stress and statin effects in combination with TNF-α were determined in human umbilical vein endothelial cells by quantitative measurements of the steady-state levels and stability of mRNA for KLF2 and its downstream target genes thrombomodulin (TM) and endothelial nitric oxide synthase (eNOS). Results: We demonstrate that prolonged shear stress has a potential that is superior to that of statins to induce the KLF2 -dependent expression of eNOS and TM, especially in the presence of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). These effects can be attributed to the sustained stabilization of KLF2 mRNA by shear, leading to an increased KLF2 protein expression and concomitant strong induction of KLF2 downstream targets. The stabilization of KLF2 mRNA is demonstrated to be dependent on signaling involving phosphoinositide 3-kinase (PI3K). Conclusion: The stabilization of KLF2 steady-state levels, as induced by prolonged shear stress but not by statins, may be essential for sustaining the quiescent, atheroprotective status of the vascular endothelium under inflammatory conditions.