1
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Wu M, Mu C, Yang H, Wang Y, Ma P, Li S, Wang Z, Lan T. 8-Br-cGMP suppresses tumor progression through EGFR/PLC γ1 pathway in epithelial ovarian cancer. Mol Biol Rep 2024; 51:140. [PMID: 38236447 DOI: 10.1007/s11033-023-09037-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 11/28/2023] [Indexed: 01/19/2024]
Abstract
BACKGROUND Cyclic guanosine monophosphate (cGMP)-dependent protein kinase I (PKG-I), a serine/threonine kinase, is important in tumor development. The present study determines that the cGMP/PKG I pathway is essential for promoting cell proliferation and survival in human ovarian cancer cells, whereas cGMP analog has been shown to lead to growth inhibition and apoptosis of various cancer cells. The role of cGMP/PKG I pathway in epithelial ovarian cancer (EOC), therefore, remains controversial. We investigated the effect of cGMP/PKG I pathway and the underlying mechanism in EOC. METHODS AND RESULTS The results showed that exogenous 8-Bromoguanosine-3', 5'-cyclic monophosphate (8-Br-cGMP) (cGMP analog) could antagonize the effects by EGF, including suppressing proliferation, invasion and migration of EOC cells. In vivo, 8-Br-cGMP hampered the growth of the xenograft tumor. Additionally, the expressions of epidermal growth factor receptor (EGFR), matrix metallopeptidase 9 (MMP9), proliferating cell nuclear antigen and Ki67 in xenograft tumor were decreased after 8-Br-cGMP intervention. Further research demonstrated that 8-Br-cGMP decreased the phosphorylation of EGFR (Y992) and downstream proteins phospholipase Cγ1 (PLC γ1) (Y783), calmodulin kinase II (T286) and inhibited cytoplasmic Ca2+ release as well as PKC transferring to cell membrane. It's worth noting that the inhibition was 8-Br-cGMP dose-dependent and 8-Br-cGMP showed similar inhibitory effect on EOC cells compared with U-73122, a specific inhibitor of PLC γ1. CONCLUSIONS The activation of endogenous PKG I by addition of exogenous 8-Br-cGMP could inhibit EOC development probably via EGFR/PLCγ1 signaling pathway. 8-Br-cGMP/PKG I provide a new insight and strategy for EOC treatment.
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Affiliation(s)
- Min Wu
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu, China
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Chunyan Mu
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China
| | - Huiwen Yang
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China
| | - Yue Wang
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China
| | - Ping Ma
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China
- Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Shibao Li
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China
- Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Zhongcheng Wang
- Department of Pathophysiology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China.
| | - Ting Lan
- Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, Xuzhou, Jiangsu, China.
- School of Medical Technology, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, People's Republic of China.
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2
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McCormick LE, Suarez C, Herring LE, Cannon KS, Kovar DR, Brown NG, Gupton SL. Multi-monoubiquitylation controls VASP-mediated actin dynamics. J Cell Sci 2024; 137:jcs261527. [PMID: 38277158 PMCID: PMC10917064 DOI: 10.1242/jcs.261527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 12/13/2023] [Indexed: 01/13/2024] Open
Abstract
The actin cytoskeleton performs multiple cellular functions, and as such, actin polymerization must be tightly regulated. We previously demonstrated that reversible, non-degradative ubiquitylation regulates the function of the actin polymerase VASP in developing neurons. However, the underlying mechanism of how ubiquitylation impacts VASP activity was unknown. Here, we show that mimicking multi-monoubiquitylation of VASP at K240 and K286 negatively regulates VASP interactions with actin. Using in vitro biochemical assays, we demonstrate the reduced ability of multi-monoubiquitylated VASP to bind, bundle, and elongate actin filaments. However, multi-monoubiquitylated VASP maintained the ability to bind and protect barbed ends from capping protein. Finally, we demonstrate the electroporation of recombinant multi-monoubiquitylated VASP protein altered cell spreading morphology. Collectively, these results suggest a mechanism in which ubiquitylation controls VASP-mediated actin dynamics.
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Affiliation(s)
- Laura E. McCormick
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Laura E. Herring
- Michael Hooker Proteomics Core, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kevin S. Cannon
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - David R. Kovar
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Nicholas G. Brown
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Stephanie L. Gupton
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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3
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Gui J, Zhou H, Wan H, Yang D, Liu Q, Zhu L, Mi Y. The Role of Vasodilator-stimulated Phosphoproteins in the Development of Malignant Tumors. Curr Cancer Drug Targets 2024; 24:477-489. [PMID: 37962042 PMCID: PMC11092557 DOI: 10.2174/0115680096262439231023110106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/06/2023] [Accepted: 09/06/2023] [Indexed: 11/15/2023]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is an actin-binding protein that includes three structural domains: Enabled/VASP homolog1 (EVH1), EVH2, and proline-rich (PRR). VASP plays an important role in various cellular behaviors related to cytoskeletal regulation. More importantly, VASP plays a key role in the progression of several malignant tumors and is associated with malignant cell proliferation, invasion, and metastasis. Here, we have summarized current studies on the impact of VASP on the development of several malignant tumors and their mechanisms. This study provides a new theoretical basis for clinical molecular diagnosis and molecular targeted therapy.
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Affiliation(s)
- Jiandong Gui
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Hangsheng Zhou
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Hongyuan Wan
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Dongjie Yang
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Qing Liu
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
- Huadong Sanatorium, 67 Dajishan, Wuxi 214122, Jiangsu Province, China
| | - Lijie Zhu
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Yuanyuan Mi
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
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4
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Ali M, Zuzga DS, Pitari GM. Differential Ser phosphorylation of vasodilator-stimulated phosphoprotein regulates colon tumor formation and growth. Life Sci 2020; 264:118671. [PMID: 33129878 DOI: 10.1016/j.lfs.2020.118671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/17/2020] [Accepted: 10/23/2020] [Indexed: 02/07/2023]
Abstract
AIMS Vasodilator-stimulated phosphoprotein (VASP) controls actin dynamics associated with the malignant phenotype of colorectal tumors. Oncogenic VASP function, in turn, is finely regulated by cyclic nucleotide-dependent phosphorylation of serine (Ser) residues 157 and 239, whose differential expression determines cell survival behavior in colon cancer. However, the role of differential VASP Ser phosphorylation in colorectal carcinogenesis remains unclear. MAIN METHODS Specific VASP phosphomutant constructs were employed to selectively silence Ser157 or Ser239 phosphorylation in human colon carcinoma cells. Cyclic nucleotide-dependent manipulation of VASP Ser phosphorylation was performed with 8-bromoadenosine 3',5'-cyclic adenosine monophosphate (8-Br-cAMP) or 8-chlorophenylthio 3',5'-cyclic guanosine monophosphate (8-CPT-cGMP). Tumorigenic and locomotory phenotypes were examined in vitro with clonogenic and wound healing assays, respectively. Finally, tumor formation and growth were investigated in vivo employing two distinct xenograft models of colorectal cancer. KEY FINDINGS Disruption of VASP Ser157 phosphorylation weakened the clonogenic and migratory abilities of human colon cancer cells, effects mimicked by 8-CPT-cGMP-dependent regulation of VASP Ser239. In contrast, inhibition of VASP Ser239 phosphorylation enhanced cell clonogenicity and migration and was phenocopied by 8-Br-cAMP-dependent regulation of VASP Ser157. Importantly, cancer cells bearing the phosphomutant construct targeting VASP Ser157 decreased, while those with the phosphomutation at Ser239 improved their abilities to establish productive tumor colonies and grow in the peritoneal cavity or subcutaneous tissues of nude mice. SIGNIFICANCE Together, present observations suggest differential VASP Ser phosphorylation is a relevant, targetable molecular event underlying tumor formation and progression in colon cancer.
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Affiliation(s)
- Mehboob Ali
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA; Department of Internal Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Wexner Medical College, The Ohio State University, OH, USA.
| | - David S Zuzga
- Department of Biology, La Salle University, Philadelphia, PA, USA; BioDetego LLC, Philadelphia, PA, USA
| | - Giovanni M Pitari
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, USA; BioDetego LLC, Philadelphia, PA, USA
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5
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Li Y, Talotta-Altenburg LM, Silimperi KA, Ciabattoni GO, Lowe-Krentz LJ. Endothelial nitric oxide synthase activation is required for heparin receptor effects on vascular smooth muscle cells. Am J Physiol Cell Physiol 2019; 318:C463-C475. [PMID: 31891520 DOI: 10.1152/ajpcell.00284.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Published studies indicate that TMEM184A is a heparin receptor that interacts with and transduces stimulation from heparin in vascular cells. Previous studies have indicated that heparin increases endothelial nitric oxide synthase (eNOS) activity in bovine endothelial cells. However, the precise mechanism remains unknown. In this study, we investigated the impact of heparin treatment and TMEM184A on eNOS's activation and the role of eNOS in heparin signaling in the cloned A7r5 rat vascular smooth muscle cell line and confirmed results in endothelial cells. We employed a combination of TMEM184A knockdown A7r5 cells along with transient eNOS knockdown and enzyme inhibitor strategies. The results indicate that heparin induces phosphorylation of eNOS. eNOS can be immunoprecipitated with TMEM184A and is internalized to the perinuclear region in a TMEM184A-dependent manner in response to heparin. We also examined how heparin treatment leads to phosphorylation of eNOS and confirmed that TMEM184A and Ca2+ were required to mediate heparin-elicited eNOS phosphorylation. Evidence supporting the involvement of transient receptor potential cation channel subfamily V member 4 with TMEM184A in this eNOS activation process is also presented.
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Affiliation(s)
- Yaqiu Li
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | | | - Kayli A Silimperi
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Grace O Ciabattoni
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Linda J Lowe-Krentz
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
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6
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Wu Y, Yuan M, Su W, Zhu M, Yao X, Wang Y, Qian H, Jiang L, Tao Y, Wu M, Pang J, Chen Y. The constitutively active PKG II mutant effectively inhibits gastric cancer development via a blockade of EGF/EGFR-associated signalling cascades. Ther Adv Med Oncol 2018; 10:1758834017751635. [PMID: 29434677 PMCID: PMC5802699 DOI: 10.1177/1758834017751635] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 11/06/2017] [Indexed: 12/30/2022] Open
Abstract
Type II cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG II) is a membrane-anchored enzyme expressed mainly in the intestinal mucosa and the brain, and is associated with various physiological or pathological processes. Upregulation of PKG II is known to induce apoptosis and inhibit proliferation and metastasis of cancer cells. The inhibitory effect of PKG II has been shown to be dependent on the inhibition of the activation of epidermal growth factor receptor (EGFR) and blockade of EGFR downstream signal transduction in vitro. However, it remains unclear whether similar phenomena/mechanisms exist in vivo and whether these effects are independent of cGMP or cGMP analogues. In the present work, nude mice with transplanted orthotopic tumours were infected with adenovirus encoding cDNA of constitutively active PKG II mutant (Ad-a-PKG II) and the effect of constitutively active PKG II (a-PKG II) on tumour development was detected. The results showed that a-PKG II effectively ameliorated gastric tumour development through delaying the growth, inducing the apoptosis, and inhibiting the metastasis and angiogenesis. The effect was related to blockade of EGFR activation and abrogation of the downstream signalling cascades. These findings provide novel insight which will benefit the development of new cancer therapies.
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Affiliation(s)
- Yan Wu
- Department of Physiology, School of Medicine, Jiangsu University. 301 Xuefu Road; and The Central Laboratory, the Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, 212013, China
| | - Miaomiao Yuan
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Wenbin Su
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Miaolin Zhu
- Department of Pathology, Jiangsu Cancer Hospital, Nanjing, China
| | - Xiaoyuan Yao
- Department of Basic Medicine, Changchun Medical College, Changchun, China
| | - Ying Wang
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Hai Qian
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Lu Jiang
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Yan Tao
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Min Wu
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Ji Pang
- Department of Physiology, Jiangsu University, Zhenjiang, China
| | - Yongchang Chen
- Department of Physiology, School of Medicine, Jiangsu University. 301 Xuefu Road; Zhenjiang, Jiangsu, 212013, China
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7
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Barone I, Giordano C, Bonofiglio D, Andò S, Catalano S. Phosphodiesterase type 5 and cancers: progress and challenges. Oncotarget 2017; 8:99179-99202. [PMID: 29228762 PMCID: PMC5716802 DOI: 10.18632/oncotarget.21837] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/23/2017] [Indexed: 01/05/2023] Open
Abstract
Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.
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Affiliation(s)
- Ines Barone
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Cinzia Giordano
- Centro Sanitario, University of Calabria, Arcavacata di Rende, CS, Italy
| | - Daniela Bonofiglio
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Sebastiano Andò
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Stefania Catalano
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy
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8
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CCM2 and PAK4 act downstream of atrial natriuretic peptide signaling to promote cell spreading. Biochem J 2017; 474:1897-1918. [PMID: 28432261 DOI: 10.1042/bcj20160841] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 12/27/2022]
Abstract
Atrial natriuretic peptide (ANP) is a cardiac hormone released by the atrium in response to stretching forces. Via its receptor, guanylyl cyclase-A (GC-A), ANP maintains cardiovascular homeostasis by exerting diuretic, natriuretic, and hypotensive effects mediated, in part, by endothelial cells. Both in vivo and in vitro, ANP enhances endothelial barrier function by reducing RhoA activity and reorganizing the actin cytoskeleton. We established mouse endothelial cells that stably express GC-A and used them to analyze the molecular mechanisms responsible for actin reorganization. Stimulation by ANP resulted in phosphorylation of myosin light chain (MLC) and promotion of cell spreading. p21-activated kinase 4 (PAK4) and cerebral cavernous malformations 2 (CCM2), a scaffold protein involved in a cerebrovascular disease, were required for the phosphorylation of MLC and promotion of cell spreading by ANP. Finally, in addition to the GC domain, the kinase homology domain of GC-A was also required for ANP/GC-A signaling. Our results indicate that CCM2 and PAK4 are important downstream mediators of ANP/GC-A signaling involved in cell spreading, an important initial step in the enhancement of endothelial barrier function.
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9
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Zamorano P, Marín N, Córdova F, Aguilar A, Meininger C, Boric MP, Golenhofen N, Contreras JE, Sarmiento J, Durán WN, Sánchez FA. S-nitrosylation of VASP at cysteine 64 mediates the inflammation-stimulated increase in microvascular permeability. Am J Physiol Heart Circ Physiol 2017; 313:H66-H71. [PMID: 28526707 DOI: 10.1152/ajpheart.00135.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/24/2017] [Accepted: 04/25/2017] [Indexed: 01/08/2023]
Abstract
We tested the hypothesis that platelet-activating factor (PAF) induces S-nitrosylation of vasodilator-stimulated phosphoprotein (VASP) as a mechanism to reduce microvascular endothelial barrier integrity and stimulate hyperpermeability. PAF elevated S-nitrosylation of VASP above baseline levels in different endothelial cells and caused hyperpermeability. To ascertain the importance of endothelial nitric oxide synthase (eNOS) subcellular location in this process, we used ECV-304 cells transfected with cytosolic eNOS (GFPeNOSG2A) and plasma membrane eNOS (GFPeNOSCAAX). PAF induced S-nitrosylation of VASP in cells with cytosolic eNOS but not in cells wherein eNOS is anchored to the cell membrane. Reconstitution of VASP knockout myocardial endothelial cells with cysteine mutants of VASP demonstrated that S-nitrosylation of cysteine 64 is associated with PAF-induced hyperpermeability. We propose that regulation of VASP contributes to endothelial cell barrier integrity and to the onset of hyperpermeability. S-nitrosylation of VASP inhibits its function in barrier integrity and leads to endothelial monolayer hyperpermeability in response to PAF, a representative proinflammatory agonist.NEW & NOTEWORTHY Here, we demonstrate that S-nitrosylation of vasodilator-stimulated phosphoprotein (VASP) on C64 is a mechanism for the onset of platelet-activating factor-induced hyperpermeability. Our results reveal a dual role of VASP in endothelial permeability. In addition to its well-documented function in barrier integrity, we show that S-nitrosylation of VASP contributes to the onset of endothelial permeability.
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Affiliation(s)
- Patricia Zamorano
- Instituto de Inmunología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Natalie Marín
- Instituto de Inmunología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Francisco Córdova
- Instituto de Inmunología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Alejandra Aguilar
- Instituto de Inmunología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Cynthia Meininger
- Department of Medical Physiology, Texas A&M Health Science Center, Temple, Texas
| | - Mauricio P Boric
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nikola Golenhofen
- Institute of Anatomy and Cell Biology, University of Ulm, Ulm, Germany; and
| | - Jorge E Contreras
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey
| | - José Sarmiento
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
| | - Walter N Durán
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey
| | - Fabiola A Sánchez
- Instituto de Inmunología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile;
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10
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Fuseler JW, Valarmathi MT. Nitric Oxide Modulates Postnatal Bone Marrow-Derived Mesenchymal Stem Cell Migration. Front Cell Dev Biol 2016; 4:133. [PMID: 27933292 PMCID: PMC5122209 DOI: 10.3389/fcell.2016.00133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/01/2016] [Indexed: 01/06/2023] Open
Abstract
Nitric oxide (NO) is a small free-radical gas molecule, which is highly diffusible and can activate a wide range of downstream effectors, with rapid and widespread cellular effects. NO is a versatile signaling mediator with a plethora of cellular functions. For example, NO has been shown to regulate actin, the microfilament, dependent cellular functions, and also acts as a putative stem cell differentiation-inducing agent. In this study, using a wound-healing model of cellular migration, we have explored the effect of exogenous NO on the kinetics of movement and morphological changes in postnatal bone marrow-derived mesenchymal stem cells (MSCs). Cellular migration kinetics and morphological changes of the migrating MSCs were measured in the presence of an NO donor (S-Nitroso-N-Acetyl-D,L-Penicillamine, SNAP), especially, to track the dynamics of single-cell responses. Two experimental conditions were assessed, in which SNAP (200 μM) was applied to the MSCs. In the first experimental group (SN-1), SNAP was applied immediately following wound formation, and migration kinetics were determined for 24 h. In the second experimental group (SN-2), MSCs were pretreated for 7 days with SNAP prior to wound formation and the determination of migration kinetics. The generated displacement curves were further analyzed by non-linear regression analysis. The migration displacement of the controls and NO treated MSCs (SN-1 and SN-2) was best described by a two parameter exponential functions expressing difference constant coefficients. Additionally, changes in the fractal dimension (D) of migrating MSCs were correlated with their displacement kinetics for all the three groups. Overall, these data suggest that NO may evidently function as a stop migration signal by disordering the cytoskeletal elements required for cell movement and proliferation of MSCs.
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Affiliation(s)
- John W Fuseler
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina Columbia, SC, USA
| | - Mani T Valarmathi
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign Urbana, IL, USA
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11
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Abstract
cGMP controls many cellular functions ranging from growth, viability, and differentiation to contractility, secretion, and ion transport. The mammalian genome encodes seven transmembrane guanylyl cyclases (GCs), GC-A to GC-G, which mainly modulate submembrane cGMP microdomains. These GCs share a unique topology comprising an extracellular domain, a short transmembrane region, and an intracellular COOH-terminal catalytic (cGMP synthesizing) region. GC-A mediates the endocrine effects of atrial and B-type natriuretic peptides regulating arterial blood pressure/volume and energy balance. GC-B is activated by C-type natriuretic peptide, stimulating endochondral ossification in autocrine way. GC-C mediates the paracrine effects of guanylins on intestinal ion transport and epithelial turnover. GC-E and GC-F are expressed in photoreceptor cells of the retina, and their activation by intracellular Ca(2+)-regulated proteins is essential for vision. Finally, in the rodent system two olfactorial GCs, GC-D and GC-G, are activated by low concentrations of CO2and by peptidergic (guanylins) and nonpeptidergic odorants as well as by coolness, which has implications for social behaviors. In the past years advances in human and mouse genetics as well as the development of sensitive biosensors monitoring the spatiotemporal dynamics of cGMP in living cells have provided novel relevant information about this receptor family. This increased our understanding of the mechanisms of signal transduction, regulation, and (dys)function of the membrane GCs, clarified their relevance for genetic and acquired diseases and, importantly, has revealed novel targets for therapies. The present review aims to illustrate these different features of membrane GCs and the main open questions in this field.
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Affiliation(s)
- Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany
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12
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Li H, Liu J, Wang W, Zhang Z, Li D, Lin K, Chen Z, Lin W. Matrix Metalloproteinase 9 and Vasodilator-Stimulated Phosphoprotein Related to Acute Kidney Injury in Severe Acute Pancreatitis Rats. Dig Dis Sci 2015; 60:3647-55. [PMID: 26264698 DOI: 10.1007/s10620-015-3820-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 07/18/2015] [Indexed: 12/26/2022]
Abstract
BACKGROUND Severe acute pancreatitis (SAP) usually results in acute renal failure. Matrix metalloproteinase 9 (MMP-9) and vasodilator-stimulated phosphoprotein (VASP) may participate in disease progression. AIM To investigate the renal expression of MMP-9 and VASP in SAP rats with acute kidney injury. METHODS A total of 100 rats were randomly assigned to sham 6-h, sham 12-h, sham 24-h, sham 36-h, sham 48-h, SAP 6-h, SAP 12-h, SAP 24-h, SAP 36-h, and SAP 48-h treatment groups (n = 10 per group). Levels of serum amylase (AMY), creatinine (Cr), and blood urea nitrogen (BUN) were determined. Renal pathology and ultrastructural examinations were performed, and renal mRNA and protein expression of MMP-9 and VASP were determined by real-time RT-PCR and Western blot, respectively. The activity of MMP-9 was assessed by gelatin zymography. RESULTS In the SAP groups, serum levels of AMY, Cr, and BUN were markedly higher than in the sham groups. The peak value of AMY was observed from 12 to 24 h, but that of Cr and BUN was observed at 36 h. Capillary endothelial cells in the renal interstitium were impaired and expression of MMP-9 and VASP in the kidney was significantly increased when compared with the sham groups. Expression of MMP-9 and VASP declined when renal damage reached a maximum after 24 h. CONCLUSIONS In the presence of acute kidney injury in SAP, the renal expression of MMP-9 and VASP is related to damage of endothelial cells in capillaries, which reached a maximum at 24 h and declined afterwards.
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Affiliation(s)
- Haitao Li
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Jianqiang Liu
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China.
| | - Wen Wang
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Zhijian Zhang
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Dazhou Li
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Kerong Lin
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Zhiping Chen
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
| | - Wulian Lin
- Department of Gastroenterology, Fuzhou General Hospital of Nanjing Command, Fuzong Clinical Medical College of Fujian Medical University, 165 Xi'erhuan North Road, Fuzhou, 350025, Fujian Province, China
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Barone I, Giordano C, Bonofiglio D, Catalano S, Andò S. Phosphodiesterase Type 5 as a Candidate Therapeutic Target in Cancers. CURRENT PATHOBIOLOGY REPORTS 2015. [DOI: 10.1007/s40139-015-0083-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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14
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Liu Y, Park JM, Oh SJ, Chang KH, Lee MY. Antiplatelet effect of a newly developed AMP-activated protein kinase activator YLF-466D. Eur J Pharmacol 2015; 760:81-7. [PMID: 25913239 DOI: 10.1016/j.ejphar.2015.03.084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/21/2015] [Accepted: 03/27/2015] [Indexed: 12/30/2022]
Abstract
AMP-activated protein kinase (AMPK) acts as a major regulator of cellular energy homeostasis. In platelets, AMPK activation stimulates endothelial nitric oxide synthase (eNOS) and its downstream signaling, and thereby inhibits platelet aggregation. In this study, a newly developed AMPK activator 3-[[(3E)-3-[(4-chlorophenyl)phenylmethylene]-2,3-dihydro-2-oxo-1H-indol-1-yl]methyl]-benzoic acid (YLF-466D) was tested for its antiplatelet activity. Treatment of isolated platelets with YLF-466D resulted in AMPK activation in a concentration-dependent manner in a range of 50-150 μM. Under the same experimental condition, YLF-466D effectively inhibited aggregation induced by platelet agonists including thrombin, ADP and collagen. Such AMPK activation and aggregation inhibition were abolished by pretreatment with the AMPK inhibitors compound C (CC) and ara-A, indicating that antiaggregatory effect of YLF-466D is mediated by AMPK. YLF-466D induced an activation-dependent eNOS phosphorylation at Ser1177, an elevation of cyclic nucleotides cGMP and cAMP, and subsequent phosphorylation of vasodilator-stimulated phosphoprotein (VASP) at Ser239 and Ser157. All these events were prevented by CC and ara-A. In addition to isolated platelets, YLF-466D attenuated whole blood aggregation induced by collagen. Taken together, YLF-466D is capable of inhibiting platelet aggregation by activating AMPK and its downstream eNOS-cGMP-PKG signaling axis. This study reconfirms the antiplatelet activity of AMPK activators and suggests the potential application of YLF-466D to antiplatelet therapy, although the in vivo and clinical validation remains to be assessed.
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Affiliation(s)
- Yingqiu Liu
- College of Pharmacy, Dongguk University, Goyang, Gyeonggi-do 410-820, Republic of Korea
| | - Jung-Min Park
- College of Pharmacy, Dongguk University, Goyang, Gyeonggi-do 410-820, Republic of Korea
| | - Seok-Jeong Oh
- College of Pharmacy, Dongguk University, Goyang, Gyeonggi-do 410-820, Republic of Korea
| | - Kyung-Hwa Chang
- College of Pharmacy, Dongguk University, Goyang, Gyeonggi-do 410-820, Republic of Korea
| | - Moo-Yeol Lee
- College of Pharmacy, Dongguk University, Goyang, Gyeonggi-do 410-820, Republic of Korea.
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15
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Serine phosphorylation of vasodilator-stimulated phosphoprotein (VASP) regulates colon cancer cell survival and apoptosis. Life Sci 2014; 123:1-8. [PMID: 25543053 DOI: 10.1016/j.lfs.2014.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/29/2014] [Accepted: 12/15/2014] [Indexed: 12/16/2022]
Abstract
AIMS In colon cancer, disease recurrence and death are associated with abnormal tumor cell survival. Vasodilator-stimulated phosphoprotein (VASP) is an actin binding protein regulating cell shape and polarity through the F-actin cytoskeleton, whose activity is controlled by cAMP-dependent phosphorylation at Ser157 and cGMP-dependent phosphorylation at Ser239. This study examined the role of differential VASP Ser phosphorylation in regulating cell survival and apoptosis in human colon carcinoma cells. MAIN METHODS Selective inhibition of VASP Ser157 or Ser239 phosphorylation in colon cancer cells was performed with specific phosphomutant constructs. F-actin organization was examined by confocal microscopy, and the balance of cell survival and death assessed by measuring acridine orange and ethidium bromide staining, caspase-3 and BAD-pS112 expression and DNA fragmentation. KEY FINDINGS In human colon carcinoma cells suppression of VASP Ser157 phosphorylation reduced F-actin content and survival and increased apoptosis, while inhibition of VASP Ser239 phosphorylation increased F-actin content and survival and reduced cell death. Also, while 8Br-cAMP induced VASP Ser157 phosphorylation and reduced cell death, treatments with 8CPT-cGMP elevated VASP Ser239 phosphorylation and promoted apoptosis. SIGNIFICANCE These findings suggest that differential VASP Ser phosphorylation represents a unique therapeutic target to control cell survival and death behavior in colon cancer. In particular, pharmacological manipulation of VASP Ser phosphorylation could be exploited to affect the malignant actin cytoskeleton and induce apoptosis in colorectal cancer cells.
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16
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Shi Z, Fu F, Yu L, Xing W, Su F, Liang X, Tie R, Ji L, Zhu M, Yu J, Zhang H. Vasonatrin peptide attenuates myocardial ischemia-reperfusion injury in diabetic rats and underlying mechanisms. Am J Physiol Heart Circ Physiol 2014; 308:H281-90. [PMID: 25485902 DOI: 10.1152/ajpheart.00666.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetes mellitus increases morbidity/mortality of ischemic heart disease. Although atrial natriuretic peptide and C-type natriuretic peptide reduce the myocardial ischemia-reperfusion damage in nondiabetic rats, whether vasonatrin peptide (VNP), the artificial synthetic chimera of atrial natriuretic peptide and C-type natriuretic peptide, confers cardioprotective effects against ischemia-reperfusion injury, especially in diabetic patients, is still unclear. This study was designed to investigate the effects of VNP on ischemia-reperfusion injury in diabetic rats and to further elucidate its mechanisms. The high-fat diet-fed streptozotocin-induced diabetic Sprague-Dawley rats were subjected to ischemia-reperfusion operation. VNP treatment (100 μg/kg iv, 10 min before reperfusion) significantly improved the instantaneous first derivation of left ventricle pressure (±LV dP/dtmax) and LV systolic pressure and reduced LV end-diastolic pressure, apoptosis index, caspase-3 activity, plasma creatine kinase (CK), and lactate dehydrogenase (LDH) activities. Moreover, VNP inhibited endoplasmic reticulum (ER) stress by suppressing glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP). These effects were mimicked by 8-bromine-cyclic guanosinemonophosphate (8-Br-cGMP), a cGMP analog, whereas they were inhibited by KT-5823, the selective inhibitor of PKG. In addition, pretreatment with tauroursodeoxycholic acid (TUDCA), a specific inhibitor of ER stress, could not further promote the VNP's cardioprotective effect in diabetic rats. In vitro H9c2 cardiomyocytes were subjected to hypoxia/reoxygenation and incubated with or without VNP (10(-8) mol/l). Gene knockdown of PKG1α with siRNA blunted VNP inhibition of ER stress and apoptosis, while overexpression of PKG1α resulted in significant decreased ER stress and apoptosis. VNP protects the diabetic heart against ischemia-reperfusion injury by inhibiting ER stress via the cGMP-PKG signaling pathway. These results suggest that VNP may have potential therapeutic value for the diabetic patients with ischemic heart disease.
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Affiliation(s)
- Zhenwei Shi
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China
| | - Feng Fu
- Department of Physiology, Fourth Military Medical University, Xi'an, China
| | - Liming Yu
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China
| | - Wenjuan Xing
- Department of Physiology, Fourth Military Medical University, Xi'an, China
| | - Feifei Su
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China; and
| | - Xiangyan Liang
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China
| | - Ru Tie
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China
| | - Lele Ji
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China
| | - Miaozhang Zhu
- Department of Physiology, Fourth Military Medical University, Xi'an, China
| | - Jun Yu
- Experimental Center, The Second Affiliated Hospital, School of Medicine, Xi'an Medical University, Xi'an, China
| | - Haifeng Zhang
- Experiment Teaching Center, Fourth Military Medical University, Xi'an, China;
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17
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Schwappacher R, Rangaswami H, Su-Yuo J, Hassad A, Spitler R, Casteel DE. cGMP-dependent protein kinase Iβ regulates breast cancer cell migration and invasion via interaction with the actin/myosin-associated protein caldesmon. J Cell Sci 2013; 126:1626-36. [PMID: 23418348 DOI: 10.1242/jcs.118190] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The two isoforms of type I cGMP-dependent protein kinase (PKGIα and PKGIβ) differ in their first ∼100 amino acids, giving each isoform unique dimerization and autoinhibitory domains. The dimerization domains form coiled-coil structures and serve as platforms for isoform-specific protein-protein interactions. Using the PKGIβ dimerization domain as an affinity probe in a proteomic screen, we identified the actin/myosin-associated protein caldesmon (CaD) as a PKGIβ-specific binding protein. PKGIβ phosphorylated human CaD on serine 12 in vitro and in intact cells. Phosphorylation on serine 12 or mutation of serine 12 to glutamic acid (S12E) reduced the interaction between CaD and myosin IIA. Because CaD inhibits myosin ATPase activity and regulates cell motility, we examined the effects of PKGIβ and CaD on cell migration and invasion. Inhibition of the NO/cGMP/PKG pathway reduced migration and invasion of human breast cancer cells, whereas PKG activation enhanced their motility and invasion. siRNA-mediated knockdown of endogenous CaD had pro-migratory and pro-invasive effects in human breast cancer cells. Reconstituting cells with wild-type CaD slowed migration and invasion; however, CaD containing a phospho-mimetic S12E mutation failed to reverse the pro-migratory and pro-invasive activity of CaD depletion. Our data suggest that PKGIβ enhances breast cancer cell motility and invasive capacity, at least in part, by phosphorylating CaD. These findings identify a pro-migratory and pro-invasive function for PKGIβ in human breast cancer cells, suggesting that PKGIβ is a potential target for breast cancer treatment.
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Affiliation(s)
- Raphaela Schwappacher
- Department of Medicine and Cancer Center, University of California San Diego, La Jolla, CA 92093, USA
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18
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Gambaryan S, Butt E, Kobsar A, Geiger J, Rukoyatkina N, Parnova R, Nikolaev VO, Walter U. The oligopeptide DT-2 is a specific PKG I inhibitor only in vitro, not in living cells. Br J Pharmacol 2013; 167:826-38. [PMID: 22612416 DOI: 10.1111/j.1476-5381.2012.02044.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE cGMP is involved in the regulation of many cellular processes including cardiac and smooth muscle contractility, aldosterone synthesis and inhibition of platelet activation. Intracellular effects cGMP are mediated by cGMP-dependent PKs, cGMP-regulated PDEs and cGMP-gated ion channels. PKG inhibitors are widely used to discriminate PKG-specific effects. They can be divided into cyclic nucleotide-binding site inhibitors such as Rp-phosphorothioate analogues (Rp-cGMPS), ATP-binding site inhibitors such as KT5823, and substrate binding site inhibitors represented by the recently described DT-oligopeptides. As it has been shown that Rp-cGMPS and KT5823 have numerous non-specific effects, we analysed the pharmacological properties of the oligopeptide (D)-DT-2 described as a highly specific, membrane-permeable, PKG inhibitor. EXPERIMENTAL APPROACH Specificity and potency of (D)-DT-2 to inhibit PKG activity was evaluated using biochemical assays in vitro and by substrate phosphorylation analysis in various cell types including human platelets, rat mesangial cells and rat neonatal cardiomyocytes. KEY RESULTS Despite potent inhibition of PKGI in vitro, (D)-DT-2 lost specificity for PKG in cell homogenates and particularly in living cells, as demonstrated by phosphorylation of different substrates. Instead, (D)-DT-2 modulated activity of other kinases including ERK, p38, PKB and PKC, thereby inducing unpredicted and often opposing functional effects. CONCLUSIONS AND IMPLICATIONS We conclude that DT-oligopeptides, as other inhibitors, cannot be used to specifically inhibit PKG in intact cells. Therefore, no specific pharmacological PKG inhibitors are available, and reliable studies of PKG signalling can only be made by using RNA knockdown or genetic deletion methods.
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Affiliation(s)
- Stepan Gambaryan
- Institute of Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany.
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19
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Cardiomyocyte-restricted overexpression of extracellular superoxide dismutase increases nitric oxide bioavailability and reduces infarct size after ischemia/reperfusion. Basic Res Cardiol 2012; 107:305. [PMID: 23099819 PMCID: PMC3505528 DOI: 10.1007/s00395-012-0305-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 09/19/2012] [Accepted: 10/01/2012] [Indexed: 11/28/2022]
Abstract
Increased levels of extracellular superoxide dismutase (ecSOD) induced by preconditioning or gene therapy protect the heart from ischemia/reperfusion injury. To elucidate the mechanism responsible for this action, we studied the effects of increased superoxide scavenging on nitric oxide (NO) bioavailability in a cardiac myocyte-specific ecSOD transgenic (Tg) mouse. Results indicated that ecSOD overexpression increased cardiac myocyte-specific ecSOD activity 27.5-fold. Transgenic ecSOD was localized to the sarcolemma and, notably, the cytoplasm of cardiac myocytes. Ischemia/reperfusion injury was attenuated in ecSOD Tg hearts, in which infarct size was decreased and LV functional recovery was improved. Using the ROS spin trap, DMPO, electron paramagnetic resonance (EPR) spectroscopy demonstrated a significant decrease in ROS in Tg hearts during the first 20 min of reperfusion. This decrease in ROS was accompanied by an increase in NO production determined by EPR using the NO spin trap, Fe-MGD. Attenuated ROS in ecSOD Tg myocytes was also supported by decreased production of peroxynitrite (ONOO−). Increased NO bioavailability was confirmed by attenuated guanylate cyclase-dependent (p-VASP) signaling. In conclusion, attenuation of ROS levels by cardiac-specific ecSOD overexpression increases NO bioavailability in response to ischemia/reperfusion and protects against reperfusion injury. These findings are the first to demonstrate increased NO bioavailability with attenuation of ROS by direct measurement of these reactive species (EPR, reactive fluorescent dyes) with cardiac-specific ecSOD expression. This is also the first indication that the predominantly extracellular SOD isoform is capable of cytosolic localization that affects myocardial intracellular signal transduction and function.
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Abstract
The cardiac hormone atrial natriuretic peptide (ANP) is critically involved in the maintenance of arterial blood pressure and intravascular volume homeostasis. Its cGMP-producing GC-A receptor is densely expressed in the microvascular endothelium of the lung and systemic circulation, but the functional relevance is controversial. Some studies reported that ANP stimulates endothelial cell permeability, whereas others described that the peptide attenuates endothelial barrier dysfunction provoked by inflammatory agents such as thrombin or histamine. Many studies in vitro addressed the effects of ANP on endothelial proliferation and migration. Again, both pro- and anti-angiogenic properties were described. To unravel the role of the endothelial actions of ANP in vivo, we inactivated the murine GC-A gene selectively in endothelial cells by homologous loxP/Cre-mediated recombination. Our studies in these mice indicate that ANP, via endothelial GC-A, increases endothelial albumin permeability in the microcirculation of the skin and skeletal muscle. This effect is critically involved in the endocrine hypovolaemic, hypotensive actions of the cardiac hormone. On the other hand the homologous GC-A-activating B-type NP (BNP), which is produced by cardiac myocytes and many other cell types in response to stressors such as hypoxia, possibly exerts more paracrine than endocrine actions. For instance, within the ischaemic skeletal muscle BNP released from activated satellite cells can improve the regeneration of neighbouring endothelia. This review will focus on recent advancements in our understanding of endothelial NP/GC-A signalling in the pulmonary versus systemic circulation. It will discuss possible mechanisms accounting for the discrepant observations made for the endothelial actions of this hormone-receptor system and distinguish between (patho)physiological and pharmacological actions. Lastly it will emphasize the potential therapeutical implications derived from the actions of NPs on endothelial permeability and regeneration.
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Affiliation(s)
- Michaela Kuhn
- Physiologisches Institut der Universität Würzburg, Würzburg, Germany.
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21
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Kukreja RC, Salloum FN, Das A. Cyclic guanosine monophosphate signaling and phosphodiesterase-5 inhibitors in cardioprotection. J Am Coll Cardiol 2012; 59:1921-7. [PMID: 22624832 DOI: 10.1016/j.jacc.2011.09.086] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/15/2011] [Accepted: 09/20/2011] [Indexed: 01/15/2023]
Abstract
Cyclic guanosine monophosphate (cGMP) is an important intracellular second messenger that mediates multiple tissue and cellular responses. The cGMP pathway is a key element in the pathophysiology of the heart and its modulation by drugs such as phosphodiesterase (PDE)-5 inhibitors and guanylate cyclase activators may represent a promising therapeutic approach for acute myocardial infarction, cardiac hypertrophy, heart failure, and doxorubicin cardiotoxicity in patients. In addition, PDE-5 inhibitors may prove to be innovative therapeutic agents for enhancing the chemosensitivity of doxorubicin while providing concurrent cardiac benefit.
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Affiliation(s)
- Rakesh C Kukreja
- Pauley Heart Center, Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
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22
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Abstract
Endothelial prostacyclin and nitric oxide potently inhibit platelet functions. Prostacyclin and nitric oxide actions are mediated by platelet adenylyl and guanylyl cyclases, which synthesize cyclic AMP (cAMP) and cyclic GMP (cGMP), respectively. Cyclic nucleotides stimulate cAMP-dependent protein kinase (protein kinase A [PKA]I and PKAII) and cGMP-dependent protein kinase (protein kinase G [PKG]I) to phosphorylate a broad panel of substrate proteins. Substrate phosphorylation results in the inactivation of small G-proteins of the Ras and Rho families, inhibition of the release of Ca(2+) from intracellular stores, and modulation of actin cytoskeleton dynamics. Thus, PKA/PKG substrates translate prostacyclin and nitric oxide signals into a block of platelet adhesion, granule release, and aggregation. cAMP and cGMP are degraded by phosphodiesterases, which might restrict signaling to specific subcellular compartments. An emerging principle of cyclic nucleotide signaling in platelets is the high degree of interconnection between activating and cAMP/cGMP-dependent inhibitory signaling pathways at all levels, including cAMP/cGMP synthesis and breakdown, and PKA/PKG-mediated substrate phosphorylation. Furthermore, defects in cAMP/cGMP pathways might contribute to platelet hyperreactivity in cardiovascular disease. This article focuses on recent insights into the regulation of the cAMP/cGMP signaling network and on new targets of PKA and PKG in platelets.
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Affiliation(s)
- A Smolenski
- UCD Conway Institute, UCD School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland.
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23
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Kobsar A, Siauw C, Gambaryan S, Hebling S, Speer C, Schubert-Unkmeir A, Eigenthaler M. Neisseria meningitidis induces platelet inhibition and increases vascular endothelial permeability via nitric oxide regulated pathways. Thromb Haemost 2011; 106:1127-38. [PMID: 22072136 DOI: 10.1160/th11-07-0491] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/17/2011] [Indexed: 12/23/2022]
Abstract
Despite antibiotic therapy, infections with Neisseria meningitidis still demonstrate a high rate of morbidity and mortality even in developed countries. The fulminant septicaemic course, named Waterhouse-Friderichsen syndrome, with massive haemorrhage into the adrenal glands and widespread petechial bleeding suggest pathophysiological inhibition of platelet function. Our data show that N. meningitidis produces the important physiological platelet inhibitor and cardiovascular signalling molecule nitric oxide (NO), also known as endothelium-derived relaxing factor (EDRF). N. meningitidis -derived NO inhibited ADP-induced platelet aggregation through the activation of soluble guanylyl cyclase (sGC) followed by an increase in platelet cyclic nucleotide levels and subsequent activation of platelet cGMP- and cAMP- dependent protein kinases (PKG and PKA). Furthermore, direct measurement of horseradish peroxidase (HRP) passage through a vascular endothelial cell monolayer revealed that N. meningitidis significantly increased endothelial monolayer permeability. Immunfluorescence analysis demonstrated NO dependent disturbances in the structure of endothelial adherens junctions after co-incubation with N. meningitidis . In contrast to platelet inhibition, the NO effects on HBMEC were not mediated by cyclic nucleotides. Our study provides evidence that NO plays an essential role in the pathophysiology of septicaemic meningococcal infection.
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Affiliation(s)
- Anna Kobsar
- Institute of Clinical Biochemistry and Pathobiochemistry /Central Laboratory, University of Wuerzburg, Germany
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24
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Fuseler JW, Valarmathi MT. Modulation of the migration and differentiation potential of adult bone marrow stromal stem cells by nitric oxide. Biomaterials 2011; 33:1032-43. [PMID: 22071099 DOI: 10.1016/j.biomaterials.2011.10.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 10/11/2011] [Indexed: 11/29/2022]
Abstract
Nitric oxide (NO) is a diffusible free radical, which serves as a pluripotent intracellular messenger in numerous cell systems. NO has been demonstrated to regulate actin dependent cellular functions and functions as a putative inductive agent in directing stem cells differentiation. In this study, we investigated the effect of exogenous NO on the kinetics of movement and morphological changes in adult bone marrow stromal cells (BMSCs) in a wound healing model of cellular migration. Cellular migration and morphological changes were determined by measurement of changes in the area and fractal dimension of BMSCs monolayer as a function of time in the presence of an NO donor (S-Nitroso-N-Acetyl-D,L-Penicillamine, SNAP) compared to untreated BMSCs. Response of the BMSCs' actin cytoskeleton and desmin to NO was assessed by determining changes in their integrated optical density (IOD) and fractal dimension at 24 h and 7 days. NO suppressed BMSCs' migration accompanied by a reduction in cell size, with maintenance of their stellate to polygonal morphology. In response to NO, the actin cytoskeleton expressed an increase in randomness but maintained a constant amount of F-actin relative to the cell size. The presence of NO also induced an increase in randomly organized cytoplasmic desmin. These data suggest that NO has an apparent inductive effect on adult BMSCs and is capable of initiating phenotypic change at the gross cellular, cytoskeletal and molecular levels. It is apparent, however, that additional factors or conditions are required to further drive the differentiation of adult BMSCs into specific phenotypes, such as cardiomyocytes.
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Affiliation(s)
- John W Fuseler
- Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC 29209, USA
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25
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Chen W, Gassner B, Börner S, Nikolaev VO, Schlegel N, Waschke J, Steinbronn N, Strasser R, Kuhn M. Atrial natriuretic peptide enhances microvascular albumin permeability by the caveolae-mediated transcellular pathway. Cardiovasc Res 2011; 93:141-51. [PMID: 22025581 PMCID: PMC3243041 DOI: 10.1093/cvr/cvr279] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Cardiac atrial natriuretic peptide (ANP) participates in the maintenance of arterial blood pressure and intravascular volume homeostasis. The hypovolaemic effects of ANP result from coordinated actions in the kidney and systemic microcirculation. Hence, ANP, via its guanylyl cyclase-A (GC-A) receptor and intracellular cyclic GMP as second messenger, stimulates endothelial albumin permeability. Ultimately, this leads to a shift of plasma fluid into interstitial pools. Here we studied the role of caveolae-mediated transendothelial albumin transport in the hyperpermeability effects of ANP. METHODS AND RESULTS Intravital microscopy studies of the mouse cremaster microcirculation showed that ANP stimulates the extravasation of fluorescent albumin from post-capillary venules and causes arteriolar vasodilatation. The hyperpermeability effect was prevented in mice with conditional, endothelial deletion of GC-A (EC GC-A KO) or with deleted caveolin-1 (cav-1), the caveolae scaffold protein. In contrast, the vasodilating effect was preserved. Concomitantly, the acute hypovolaemic action of ANP was abolished in EC GC-A KO and Cav-1(-/-) mice. In cultured microvascular rat fat pad and mouse lung endothelial cells, ANP stimulated uptake and transendothelial transport of fluorescent albumin without altering endothelial electrical resistance. The stimulatory effect on albumin uptake was prevented in GC-A- or cav-1-deficient pulmonary endothelia. Finally, preparation of caveolin-enriched lipid rafts from mouse lung and western blotting showed that GC-A and cGMP-dependent protein kinase I partly co-localize with Cav-1 in caveolae microdomains. CONCLUSION ANP enhances transendothelial caveolae-mediated albumin transport via its GC-A receptor. This ANP-mediated cross-talk between the heart and the microcirculation is critically involved in the regulation of intravascular volume.
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Affiliation(s)
- Wen Chen
- Institute of Physiology, University of Würzburg, Germany
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cGMP-dependent protein kinases as potential targets for colon cancer prevention and treatment. Future Med Chem 2011; 2:65-80. [PMID: 21426046 DOI: 10.4155/fmc.09.142] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In recent years, several antitumor signaling pathways mediated by the cGMP-dependent protein kinases have been identified in colon cancer cells. This review aims to present the mounting evidence in favor of cGMP/protein kinase G (PKG) signaling as a therapeutic strategy in colon cancer. The homeostatic and tumor suppressive effects of cGMP in the intestine are uncontested, but the signaling details are not understood. PKG is the central cGMP effector, and can block proliferation and tumor angiogenesis by inhibiting β-catenin/TCF and SOX9 signaling. Therapeutic activation of cGMP/PKG offers a promising avenue for the prevention and treatment of colon cancer, but additional preclinical studies are needed to fully understand the potential of this system.
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Routray C, Liu C, Yaqoob U, Billadeau DD, Bloch KD, Kaibuchi K, Shah VH, Kang N. Protein kinase G signaling disrupts Rac1-dependent focal adhesion assembly in liver specific pericytes. Am J Physiol Cell Physiol 2011; 301:C66-74. [PMID: 21451103 DOI: 10.1152/ajpcell.00038.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Nitric oxide (NO) regulates the function of perivascular cells (pericytes), including hepatic stellate cells (HSC), mainly by activating cGMP and cGMP-dependent kinase (PKG) via NO/cGMP paracrine signaling. Although PKG is implicated in integrin-mediated cell adhesion to extracellular matrix, whether or how PKG signaling regulates the assembly of focal adhesion complexes (FA) and migration of HSC is not known. With the help of complementary molecular and cell biological approaches, we demonstrate here that activation of PKG signaling in HSC inhibits vascular tubulogenesis, migration/chemotaxis, and assembly of mature FA plaques, as assessed by vascular tubulogenesis assays and immunofluorescence localization of FA markers such as vinculin and vasodilator-stimulated phosphoprotein (VASP). To determine whether PKG inhibits FA assembly by phosphorylation of VASP at Ser-157, Ser-239, and Thr-278, we mutated these putative phosphorylation sites to alanine (VASP3A, phosphoresistant mutant) or aspartic acid (VASP3D, phosphomimetic), respectively. Data generated from these two mutants suggest that the effect of PKG on FA is independent of these three phosphorylation sites. In contrast, activation of PKG inhibits the activity of small GTPase Rac1 and its association with the effector protein IQGAP1. Moreover, PKG activation inhibits the formation of a trimeric protein complex containing Rac1, IQGAP1, and VASP. Finally, we found that expression of a constitutively active Rac1 mutant abolishes the inhibitory effects of PKG on FA formation. In summary, our data suggest that activation of PKG signaling in pericytes inhibits FA formation by inhibiting Rac1.
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Affiliation(s)
- Chittaranjan Routray
- GI Research Unit and Cancer Cell Biology Program, Mayo Clinic, Rochester, Minnesota 55905, USA
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28
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Sayner SL. Emerging themes of cAMP regulation of the pulmonary endothelial barrier. Am J Physiol Lung Cell Mol Physiol 2011; 300:L667-78. [PMID: 21335524 DOI: 10.1152/ajplung.00433.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The presence of excess fluid in the interstitium and air spaces of the lung presents severe restrictions to gas exchange. The pulmonary endothelial barrier regulates the flux of fluid and plasma proteins from the vascular space into the underlying tissue. The integrity of this endothelial barrier is dynamically regulated by transitions in cAMP (3',5'-cyclic adenosine monophosphate), which are synthesized in discrete subcellular compartments. Cyclic AMP generated in the subplasma membrane compartment acts through PKA and Epac (exchange protein directly activated by cAMP) to tighten cell adhesions, strengthen cortical actin, reduce actomyosin contraction, and decrease permeability. Confining cAMP within the subplasma membrane space is critical to its barrier-protective properties. When cAMP escapes the near membrane compartment and gains access to the cytosolic compartment, or when soluble adenylyl cyclases generate cAMP within the cytosolic compartment, this second messenger activates established cytosolic cAMP signaling cascades to perturb the endothelial barrier through PKA-mediated disruption of microtubules. Thus the concept of cAMP compartmentalization in endothelial barrier regulation is gaining momentum and new possibilities are being unveiled for cytosolic cAMP signaling with the emergence of the bicarbonate-regulated mammalian soluble adenylyl cyclase (sAC or AC10).
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Affiliation(s)
- Sarah L Sayner
- Dept. of Cell Biology and Neuroscience, Member, Center for Lung Biology, College of Medicine, Univ. of South Alabama, Mobile, AL 36688, USA.
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29
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Rangaswami H, Schwappacher R, Marathe N, Zhuang S, Casteel DE, Haas B, Chen Y, Pfeifer A, Kato H, Shattil S, Boss GR, Pilz RB. Cyclic GMP and protein kinase G control a Src-containing mechanosome in osteoblasts. Sci Signal 2010; 3:ra91. [PMID: 21177494 DOI: 10.1126/scisignal.2001423] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mechanical stimulation is crucial for bone growth and remodeling, and fluid shear stress promotes anabolic responses in osteoblasts through multiple second messengers, including nitric oxide (NO). NO triggers production of cyclic guanosine 3',5'-monophosphate (cGMP), which in turn activates protein kinase G (PKG). We found that the NO-cGMP-PKG signaling pathway activates Src in mechanically stimulated osteoblasts to initiate a proliferative response. PKGII was necessary for Src activation, a process that also required the interaction of Src with β₃ integrins and dephosphorylation of Src by a complex containing the phosphatases SHP-1 (Src homology 2 domain-containing tyrosine phosphatase 1) and SHP-2. PKGII directly phosphorylated and stimulated SHP-1 activity, and fluid shear stress triggered the recruitment of PKGII, Src, SHP-1, and SHP-2 to a mechanosome containing β₃ integrins. PKGII-null mice showed defective Src and ERK (extracellular signal-regulated kinase) signaling in osteoblasts and decreased ERK-dependent gene expression in bone. Our findings reveal a convergence of NO-cGMP-PKG and integrin signaling and establish a previously unknown mechanism of Src activation. These results support the use of PKG-activating drugs to mimic the anabolic effects of mechanical stimulation of bone in the treatment of osteoporosis.
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Affiliation(s)
- Hema Rangaswami
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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30
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Lin WH, Nelson SE, Hollingsworth RJ, Chung CY. Functional roles of VASP phosphorylation in the regulation of chemotaxis and osmotic stress response. Cytoskeleton (Hoboken) 2010; 67:259-71. [PMID: 20191567 DOI: 10.1002/cm.20443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) plays crucial roles in controlling F-actin-driven processes and growing evidence indicates that VASP function is modulated by phosphorylation at multiple sites. However, the complexity of mammalian system prevents the clear understanding of the role of VASP phosphorylation. In this study, we took advantage of Dictyostelium which possesses only one member of the Ena/VASP family to investigate the functional roles of VASP phosphorylation. Our results demonstrated that hyperosmotic stress and cAMP stimulation cause VASP phosphorylation. VASP phosphorylation plays a negative role for the early steps of filopodia/microspikes formation. VASP phosphorylation appears to modulate VASP localization at the membrane cortex and its interactions with WASP and WIPa. Analysis of chemotaxis of cells expressing VASP mutants showed that VASP phosphorylation is required for the establishment of cell polarity under a cAMP gradient.
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Affiliation(s)
- Wan-Hsin Lin
- Department of Biological Sciences, School of Art and Science, Vanderbilt University, Nashville, Tennessee, USA
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31
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Kang N, Yaqoob U, Geng Z, Bloch K, Liu C, Gomez T, Billadeau D, Shah V. Focal adhesion assembly in myofibroblasts fosters a microenvironment that promotes tumor growth. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:1888-900. [PMID: 20802179 DOI: 10.2353/ajpath.2010.100187] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cells within the tumor microenvironment influence tumor growth through multiple mechanisms. Pericytes such as hepatic stellate cells are an important cell within the tumor microenvironment; their transformation into highly motile myofibroblasts leads to angiogenesis, stromal cell recruitment, matrix deposition, and ensuing tumor growth. Thus, a better understanding of mechanisms that regulate motility of pericytes is required. Focal adhesions (FAs) form a physical link between the extracellular environment and the actin cytoskeleton, a requisite step for cell motility. FAs contain a collection of proteins including the Ena/VASP family member, vasodilator-stimulated phosphoprotein (VASP); however, a role for VASP in FA development has been elusive. Using a comprehensive siRNA knockdown approach and a variety of VASP mutants coupled with complementary cell imaging methodologies, we demonstrate a requirement of VASP for optimal development of FAs and cell spreading in LX2 liver myofibroblasts, which express high levels of endogenous VASP. Rac1, a binding partner of VASP, acts in tandem with VASP to regulate FAs. In vivo, perturbation of Ena/VASP function in tumor myofibroblast precursor cells significantly reduces pericyte recruitment to tumor vasculature, myofibroblastic transformation, tumor angiogenesis, and tumor growth, providing in vivo pathobiologic relevance to these findings. Taken together, our results identify Ena/VASP as a significant modifier of tumor growth through regulation of FA dynamics and ensuing pericyte/myofibroblast function within the tumor microenvironment.
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32
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Jaeger V, Hoppe S, Petermann P, Liebig T, Jansen MK, Renné T, Knebel-Mörsdorf D. Herpes simplex virus type 1 entry into epithelial MDCKII cells: role of VASP activities. J Gen Virol 2010; 91:2152-7. [PMID: 20463151 DOI: 10.1099/vir.0.021055-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
VASP is an actin-regulatory protein that links signalling to remodelling of the cytoskeleton. We investigated the role of VASP during entry of herpes simplex viruses into epithelial MDCKII cells. As VASP functions are regulated by phosphorylations, the phosphorylation pattern was determined upon infection. Phosphorylated VASP decreased temporarily at 15 and 30 min after infection. The impact of phosphorylated VASP was addressed by overexpression of phosphomimetic VASP mutants. Our results revealed that phosphorylated VASP slightly reduced the number of infected cells. Expression studies with deletion mutants further indicated minor effects of VASP on infection efficiency, whereas RNA interference studies demonstrated that reduced VASP expression did not suppress infection. We conclude that VASP activities alone may contribute to herpes simplex virus infection to only a minor extent.
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Affiliation(s)
- Verena Jaeger
- Max-Planck-Institute for Neurological Research, D-50931 Cologne, Germany
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33
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Ermolina LV, Martynova NI, Zaraĭskiĭ AG. [The cytoskeletal protein zyxin--a universal regulator of cell adhesion and gene expression]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2010; 36:29-37. [PMID: 20386576 DOI: 10.1134/s1068162010010036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The attachment of a cell to an extracellular matrix or the surface of another cells affects not only the cell motility, but also gene expression. In view of this, an important problem is to establish the molecular mechanisms of signal transduction from the receptors of cell adhesion to the nucleus, in particular, to identify and investigate the protein transducers of these signals. One of these transducers, the LIM domain protein zyxin, is predominantly localized at the sites of cell adhesion, where it participates in the assembly of actin filaments. Owing to its location near the inner surface of the membrane, zyxin can interact with the transmembrane receptors of some signaling cascades and affect the signal transduction from the extracellular ligands of these receptors. Furthermore, under particular conditions, zyxin moves from the sites of cell contacts to the nucleus, where it directly participates in the regulation of gene expression. Of particular interest is the function of zyxin as a possible coordinator of gene expression and morphogenetic movements in embryogenesis. The published data discussed in the present review indicate the important role of zyxin in transmitting information from the regions of cell contacts to the genetic apparatus of the cell.
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34
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Schlegel N, Waschke J. Vasodilator-stimulated phosphoprotein: crucial for activation of Rac1 in endothelial barrier maintenance. Cardiovasc Res 2010; 87:1-3. [PMID: 20308204 DOI: 10.1093/cvr/cvq093] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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35
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Ge F, Xiao CL, Yin XF, Lu CH, Zeng HL, He QY. Phosphoproteomic analysis of primary human multiple myeloma cells. J Proteomics 2010; 73:1381-90. [PMID: 20230923 DOI: 10.1016/j.jprot.2010.03.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 02/20/2010] [Accepted: 03/06/2010] [Indexed: 10/19/2022]
Abstract
Multiple myeloma (MM) is a malignant disorder of differentiated B cells. Clonal expansion of the tumor results in the excessive production of monoclonal immunoglobulin (Ig) which is a diagnostic feature of this disease. Previous investigations have demonstrated the alteration of the ERK, jun kinase, STAT, and AKT kinase signaling cascades in MM cells, suggesting that deregulated phosphorylation may contribute to MM pathogenesis. However, systematic analysis of the phosphoproteome in MM cells has not been reported. Here, we described a large-scale phosphorylation analysis of primary MM cells. Using a separation strategy involving immunomagnetic bead-positive selection of MM cells, preparative SDS-PAGE for prefractionation, in-gel digestion with trypsin, and titanium dioxide enrichment of phosphopeptides, followed by LC-MS/MS analysis employing a hybrid LTQ-Orbitrap mass spectrometer, we were able to catalog a substantial portion of the phosphoproteins present in primary MM cells. This analysis led to the identification of 530 phosphorylation sites from 325 unique phosphopeptides corresponding to 260 proteins at false positive rate (FPR) of 1.3%. This dataset provides an important resource for future studies on phosphorylation and carcinogenesis analysis of multiple myeloma.
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Affiliation(s)
- Feng Ge
- Institute of Life and Health Engineering and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
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36
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Defawe OD, Kim S, Chen L, Huang D, Kenagy RD, Renné T, Walter U, Daum G, Clowes AW. VASP phosphorylation at serine239 regulates the effects of NO on smooth muscle cell invasion and contraction of collagen. J Cell Physiol 2009; 222:230-7. [PMID: 19798690 DOI: 10.1002/jcp.21942] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Nitric oxide triggers cGMP-dependent kinase-mediated phosphorylation of the actin regulator vasodilator-stimulated phosphoprotein (VASP) at residue serine239. The function of this phosphorylation for smooth muscle cell (SMC) adhesion, spreading, matrix contraction, and invasion is not well understood. We reconstituted VASP deficient SMC with wild-type VASP (wt-VASP) or VASP mutants that mimic "locked" serine239 phosphorylation (S239D-VASP) or "blocked" serine239 phosphorylation (S239A-VASP). Collagen gel contraction was reduced in S239D-VASP compared to S239A-VASP and wt-VASP expressing cells and nitric oxide (NO) stimulation decreased gel contraction of wt-VASP reconstituted SMC. Invasion of collagen was enhanced in S239D-VASP and NO-stimulated wild-type SMCs compared to S239A-VASP expressing cells. Expression of S239D-VASP impaired SMC attachment to collagen, reduced the number of membrane protrusions, and caused cell rounding compared to expression of S239A-VASP. Treatment of wt-VASP reconstituted SMCs with NO exerted similar effects as expression of S239D-VASP. As unstimulated cells were spreading on collagen S239A-VASP and wt-VASP localized to actin fibers whereas S239D-VASP was enriched in the cytosol. NO interferes with SMC invasion and contraction of collagen matrices. This requires phosphorylation of VASP on serine239, which reduces VASP binding to actin fibers. These findings support the conclusion that VASP phosphorylation at serine239 regulates cytoskeleton remodeling.
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Affiliation(s)
- Olivier D Defawe
- Department of Surgery, University of Washington, Seattle, Washington 98109, USA
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37
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Benz PM, Blume C, Seifert S, Wilhelm S, Waschke J, Schuh K, Gertler F, Münzel T, Renné T. Differential VASP phosphorylation controls remodeling of the actin cytoskeleton. J Cell Sci 2009; 122:3954-65. [PMID: 19825941 DOI: 10.1242/jcs.044537] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins of the Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family link signal transduction pathways to actin cytoskeleton dynamics. VASP is substrate of cAMP-dependent, cGMP-dependent and AMP-activated protein kinases that primarily phosphorylate the sites S157, S239 and T278, respectively. Here, we systematically analyzed functions of VASP phosphorylation patterns for actin assembly and subcellular targeting in vivo and compared the phosphorylation effects of Ena/VASP family members. Methods used were the reconstitution of VASP-null cells with ;locked' phosphomimetic VASP mutants, actin polymerization of VASP mutants in vitro and in living cells, site-specific kinase-mediated VASP phosphorylation, and analysis of the endogenous protein with phosphorylation-status-specific antibodies. Phosphorylation at S157 influenced VASP localization, but had a minor impact on F-actin assembly. Phosphorylation of the S157-equivalent site in the Ena/VASP family members Mena and EVL had no effect on the ratio of cellular F-actin to G-actin. By contrast, VASP phosphorylation at S239 (and the equivalent site in Mena) or T278 impaired VASP-driven actin filament formation. The data show that VASP functions are precisely regulated by differential phosphorylation and provide new insights into cytoskeletal control by serine/threonine kinase-dependent signaling pathways.
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Affiliation(s)
- Peter M Benz
- Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Würzburg, Germany
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38
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Sartoretto JL, Jin BY, Bauer M, Gertler FB, Liao R, Michel T. Regulation of VASP phosphorylation in cardiac myocytes: differential regulation by cyclic nucleotides and modulation of protein expression in diabetic and hypertrophic heart. Am J Physiol Heart Circ Physiol 2009; 297:H1697-710. [PMID: 19734360 DOI: 10.1152/ajpheart.00595.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is a major substrate for cyclic nucleotide-dependent kinases that has been implicated in cardiac pathology, yet many aspects of VASP's molecular regulation in cardiomyocytes are incompletely understood. In these studies, we explored the role of VASP, both in signaling pathways in isolated murine myocytes, as well as in a model of cardiac hypertrophy in VASP(null) mice. We found that the beta-adrenergic agonist isoproterenol promotes the rapid and reversible phosphorylation of VASP at Ser157 and Ser239. Forskolin and the cAMP analog 8-(4-chlorophenylthio)-cAMP promote a similar pattern of VASP phosphorylation at both sites. The effects of isoproterenol are blocked by atenolol and by compound H-89, an inhibitor of the cAMP-dependent protein kinase. By contrast, phosphorylation of VASP only at Ser239 is seen following activation of particulate guanylate cyclase by atrial natriuretic peptide, or following activation of soluble guanylate cyclase by sodium nitroprusside, or following treatment of myocytes with cGMP analog. We found that basal and isoproterenol-induced VASP phosphorylation is entirely unchanged in cardiomyocytes isolated from either endothelial or neuronal nitric oxide synthase knockout mice. In cardiomyocytes isolated from diabetic mice, only basal VASP phosphorylation is increased, whereas, in cells isolated from mice subjected to ascending aortic constriction (AAC), we found a significant increase in basal VASP expression, along with an increase in VASP phosphorylation, compared with cardiac myocytes isolated from sham-operated mice. Moreover, there is further increase in VASP phosphorylation in cells isolated from hypertrophic hearts following isoproterenol treatment. Finally, we found that VASP(null) mice subjected to transverse aortic constriction develop cardiac hypertrophy with a pattern similar to VASP(+/+) mice. Our findings establish differential receptor-modulated regulation of VASP phosphorylation in cardiomyocytes by cyclic nucleotides. Furthermore, these studies demonstrate for the first time that VASP expression is upregulated in hypertrophied heart.
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Affiliation(s)
- Juliano L Sartoretto
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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39
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Kuhn M, Völker K, Schwarz K, Carbajo-Lozoya J, Flögel U, Jacoby C, Stypmann J, van Eickels M, Gambaryan S, Hartmann M, Werner M, Wieland T, Schrader J, Baba HA. The natriuretic peptide/guanylyl cyclase--a system functions as a stress-responsive regulator of angiogenesis in mice. J Clin Invest 2009; 119:2019-30. [PMID: 19487812 DOI: 10.1172/jci37430] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 04/08/2009] [Indexed: 12/22/2022] Open
Abstract
Cardiac atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) modulate blood pressure and volume by activation of the receptor guanylyl cyclase-A (GC-A) and subsequent intracellular cGMP formation. Here we report what we believe to be a novel function of these peptides as paracrine regulators of vascular regeneration. In mice with systemic deletion of the GC-A gene, vascular regeneration in response to critical hind limb ischemia was severely impaired. Similar attenuation of ischemic angiogenesis was observed in mice with conditional, endothelial cell-restricted GC-A deletion (here termed EC GC-A KO mice). In contrast, smooth muscle cell-restricted GC-A ablation did not affect ischemic neovascularization. Immunohistochemistry and RT-PCR revealed BNP expression in activated satellite cells within the ischemic muscle, suggesting that local BNP elicits protective endothelial effects. Since within the heart, BNP is mainly induced in cardiomyocytes by mechanical load, we investigated whether the natriuretic peptide/GC-A system also regulates angiogenesis accompanying load-induced cardiac hypertrophy. EC GC-A KO hearts showed diminished angiogenesis, mild fibrosis, and diastolic dysfunction. In vitro BNP/GC-A stimulated proliferation and migration of cultured microvascular endothelia by activating cGMP-dependent protein kinase I and phosphorylating vasodilator-stimulated phosphoprotein and p38 MAPK. We therefore conclude that BNP, produced by activated satellite cells within ischemic skeletal muscle or by cardiomyocytes in response to pressure load, regulates the regeneration of neighboring endothelia via GC-A. This paracrine communication might be critically involved in coordinating muscle regeneration/hypertrophy and angiogenesis.
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Affiliation(s)
- Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany.
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Cyclic GMP-dependent protein kinase II inhibits cell proliferation, Sox9 expression and Akt phosphorylation in human glioma cell lines. Oncogene 2009; 28:3121-31. [PMID: 19543319 DOI: 10.1038/onc.2009.168] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Earlier we used a glioma model to identify loci in the mouse genome, which were repeatedly targeted by platelet-derived growth factor (PDGF)-containing Moloney murine leukemia viruses. The gene Prkg2, encoding cyclic guanosine monophosphate (cGMP)-dependent protein kinase II, cGKII, was tagged by retroviral insertions in two brain tumors. The insertions were both situated upstream of the kinase domain and suggested creating a truncated form of the cGKII protein. We transfected different human glioma cell lines with Prkg2 and found an overall reduction in colony formation and cell proliferation compared with controls transfected with truncated Prkg2 (lacking the kinase domain) or empty vector. All glioma cells transfected with the cGKII phosphorylate vasodilator-stimulated phosphoprotein, VASP, after cGMP analog treatment. Glioma cell lines positive for the Sox9 transcription factor showed reduced Sox9 expression when Prkg2 was stably transfected. When cGKII was activated by cGMP analog treatment, Sox9 was phosphorylated, Sox9 protein expression was suppressed and the glioma cell lines displayed loss of cell adhesion, inhibition of Akt phosphorylation and G1 arrest. Sox9 repression by siRNA was similarly shown to reduce glioma cell proliferation. Expression analysis of stem and glial lineage cell markers also suggests that cGKII induces differentiation of glioma cell lines. These findings describe an anti-proliferative role of cGKII in human glioma biology and would further explain the retroviral tagging of the cGKII gene during brain tumor formation in PDGF-induced tumors.
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Tsai EJ, Kass DA. Cyclic GMP signaling in cardiovascular pathophysiology and therapeutics. Pharmacol Ther 2009; 122:216-38. [PMID: 19306895 PMCID: PMC2709600 DOI: 10.1016/j.pharmthera.2009.02.009] [Citation(s) in RCA: 298] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 02/07/2023]
Abstract
Cyclic guanosine 3',5'-monophosphate (cGMP) mediates a wide spectrum of physiologic processes in multiple cell types within the cardiovascular system. Dysfunctional signaling at any step of the cascade - cGMP synthesis, effector activation, or catabolism - have been implicated in numerous cardiovascular diseases, ranging from hypertension to atherosclerosis to cardiac hypertrophy and heart failure. In this review, we outline each step of the cGMP signaling cascade and discuss its regulation and physiologic effects within the cardiovascular system. In addition, we illustrate how cGMP signaling becomes dysregulated in specific cardiovascular disease states. The ubiquitous role cGMP plays in cardiac physiology and pathophysiology presents great opportunities for pharmacologic modulation of the cGMP signal in the treatment of cardiovascular diseases. We detail the various therapeutic interventional strategies that have been developed or are in development, summarizing relevant preclinical and clinical studies.
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Affiliation(s)
- Emily J Tsai
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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HDAC5 is a repressor of angiogenesis and determines the angiogenic gene expression pattern of endothelial cells. Blood 2009; 113:5669-79. [PMID: 19351956 DOI: 10.1182/blood-2009-01-196485] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Class IIa histone deacetylases (HDACs) are signal-responsive regulators of gene expression involved in vascular homeostasis. To investigate the differential role of class IIa HDACs for the regulation of angiogenesis, we used siRNA to specifically suppress the individual HDAC isoenzymes. Silencing of HDAC5 exhibited a unique pro-angiogenic effect evidenced by increased endothelial cell migration, sprouting, and tube formation. Consistently, overexpression of HDAC5 decreased sprout formation, indicating that HDAC5 is a negative regulator of angiogenesis. The antiangiogenic activity of HDAC5 was independent of myocyte enhancer factor-2 binding and its deacetylase activity but required a nuclear localization indicating that HDAC5 might affect the transcriptional regulation of gene expression. To identify putative HDAC5 targets, we performed microarray expression analysis. Silencing of HDAC5 increased the expression of fibroblast growth factor 2 (FGF2) and angiogenic guidance factors, including Slit2. Antagonization of FGF2 or Slit2 reduced sprout induction in response to HDAC5 siRNA. Chromatin immunoprecipitation assays demonstrate that HDAC5 binds to the promoter of FGF2 and Slit2. In summary, HDAC5 represses angiogenic genes, such as FGF2 and Slit2, which causally contribute to capillary-like sprouting of endothelial cells. The derepression of angiogenic genes by HDAC5 inactivation may provide a useful therapeutic target for induction of angiogenesis.
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43
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Calcium and cyclic nucleotides affect TNF-alpha-induced stem cell migration. Biochem Biophys Res Commun 2009; 382:241-6. [PMID: 19233128 DOI: 10.1016/j.bbrc.2009.02.068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Accepted: 02/13/2009] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to study the effect of calcium, cyclic AMP (cAMP) and cyclic GMP (cGMP) on embryonic stem cell (ESC) motility during TNF-alpha-induced chemotaxis. ESCs were monitored using a chemotaxis chamber, with different concentrations of calcium or cAMP or cGMP added to the medium. Changes in intracellular calcium ([Ca(2+)](i)) were measured with the fluorescent dye fura-2/AM. We combined migratory parameters in a mathematical model and described it as "mobility". After adding calcium, a dose-dependant increase in cell speed was found. Cyclic AMP increased mobility as well as the [Ca(2+)](i). In contrast, adding dbcGMP resulted in a significant decrease in the mobility of the ESCs. During migration ESCs showed an increase in [Ca(2+)](i). Furthermore, TNF-alpha dramatically increased the movement as well as the directionality of ESCs. These results demonstrate that ESCs are highly motile and respond to different concentrations of calcium in a dose-related manner.
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Schlegel N, Waschke J. VASP is involved in cAMP-mediated Rac 1 activation in microvascular endothelial cells. Am J Physiol Cell Physiol 2008; 296:C453-62. [PMID: 19118163 DOI: 10.1152/ajpcell.00360.2008] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulating evidence points to a significant role of vasodilator-stimulated phosphoprotein (VASP) in the maintenance of endothelial barrier functions. We have recently shown that impaired barrier functions in VASP-deficient microvascular myocardial endothelial cells (MyEnd VASP(-/-)) correlated with decreased Rac 1 activity. To further test the hypothesis that VASP is involved in regulation of Rac 1 activity, we studied cAMP-dependent Rac 1 activation. Both inhibition of Rac 1 activation by NSC-23766 and inhibition of PKA by PKI completely blunted the efficacy of forskolin/rolipram (F/R)-mediated cAMP increase to stabilize barrier functions as revealed by measurements of transendothelial resistance (TER). Because these results indicate that PKA/Rac 1 activation is important for barrier stabilization, we tested this signaling pathway in VASP(-/-) cells. We found that F/R and isoproterenol reduced permeability measured as FITC-dextran flux across VASP(-/-) monolayers, but not below baseline levels of wild-type cells (WT). Moreover, cAMP-mediated Rac 1 activation was reduced to approximately 50% of WT levels, and both PKA inhibition by PKI and PKA anchoring via A kinase anchoring peptides (AKAPs) by HT31 almost completely abolished Rac 1 activation in VASP(-/-) and WT endothelium. Accordingly, HT31 significantly reduced F/R-mediated TER increase in WT cells and completely blocked the protective effect of cAMP on endothelial barrier properties. Together, our data underline the significant role of cAMP-mediated Rac 1 activation for endothelial barrier stabilization and demonstrate that both AKAP-mediated PKA anchoring and VASP are required for this process.
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Affiliation(s)
- Nicolas Schlegel
- Institute of Anatomy and Cell Biology, Julius-Maximilians-Univ., Koellikerstr. 6, 97070 Würzburg, Germany
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Gambaryan S, Kobsar A, Hartmann S, Birschmann I, Kuhlencordt PJ, Müller-Esterl W, Lohmann SM, Walter U. NO-synthase-/NO-independent regulation of human and murine platelet soluble guanylyl cyclase activity. J Thromb Haemost 2008; 6:1376-84. [PMID: 18485089 DOI: 10.1111/j.1538-7836.2008.03014.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Platelets, specialized adhesive cells, play key roles in normal and pathological hemostasis through their ability to rapidly adhere to subendothelial matrix proteins (adhesion) and to other activated platelets (aggregation), functions which are inhibited by nitric oxide (NO). Platelets have been reported to be regulated not only by exogenous endothelium-derived NO, but also by two isoforms of NO synthase, endothelial (eNOS) and inducible (iNOS), endogenously expressed in platelets. however, data concerning expression, regulation and function of eNOS AND iNOS in platelets remain controversial. METHODS AND RESULTS Using important positive (endothelial cells, stimulated macrophages) and negative (eNOS/iNOS knock-out mouse) controls, as well as human platelets highly purified by a newly developed protocol, we now demonstrate that human and mouse platelets do not contain eNOS/iNOS proteins or mRNA. NOS substrate (L-arginine), NOS inhibitors (L-NAME, L-NMMA), and eNOS/iNOS deficiency did not produce detectable functional effects on human and mouse platelets. von Willebrand factor (VWF)/ristocetin treatment of platelets increased cGMP by NO-independent activation of soluble guanylyl cyclase (sGC) which correlated with Src kinase-dependent phosphorylation of sGC beta(1)-subunit-Tyr(192). CONCLUSIONS Human and mouse platelets do not express eNOS/iNOS. VWF/ristocetin-mediated activation of the sGC/cGMP signaling pathway may contribute to feedback platelet inhibition.
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Affiliation(s)
- S Gambaryan
- Institute of Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany
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Schreier B, Börner S, Völker K, Gambaryan S, Schäfer SC, Kuhlencordt P, Gassner B, Kuhn M. The heart communicates with the endothelium through the guanylyl cyclase-A receptor: acute handling of intravascular volume in response to volume expansion. Endocrinology 2008; 149:4193-9. [PMID: 18450968 PMCID: PMC2488219 DOI: 10.1210/en.2008-0212] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Atrial natriuretic peptide (ANP) regulates arterial blood pressure and volume. Its guanylyl cyclase-A (GC-A) receptor is expressed in vascular endothelium and mediates increases in cGMP, but the functional relevance is controversial. Notably, mice with endothelial-restricted GC-A deletion [EC GC-A knockout (KO) mice] exhibit significant chronic hypervolemic hypertension. The present study aimed to characterize the endothelial effects of ANP and their relevance for the acute regulation of intravascular fluid volume. We studied the effect of ANP on microvascular permeability to fluorescein isothiocyanate-labeled albumin (BSA) using intravital microscopy on mouse dorsal skinfold chambers. Local superfusion of ANP (100 nm) increased microvascular fluorescein isothiocyanate-BSA extravasation in control but not EC GC-A KO mice. Intravenous infusion of synthetic ANP (500 ng/kg x min) caused immediate increases in hematocrit in control mice, indicating intravascular volume contraction. In EC GC-A KO mice, the hematocrit responses were not only abolished but even reversed. Furthermore, acute vascular volume expansion, which caused release of endogenous cardiac ANP, did not affect resting central venous pressure of control mice but rapidly and significantly increased central venous pressure of EC GC-A KO mice. In cultured lung endothelial cells, ANP provoked cGMP-dependent protein kinase I-mediated phosphorylation of vasodilator-stimulated phosphoprotein. We conclude that ANP, via GC-A, enhances microvascular endothelial macromolecule permeability in vivo. This effect might be mediated by cGMP-dependent protein kinase I-dependent phosphorylation of vasodilator-stimulated phosphoprotein. Modulation of transcapillary protein and fluid transport may represent one of the most important hypovolemic actions of ANP.
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Affiliation(s)
- Barbara Schreier
- Institutes of Physiology, University of Würzburg, D-97070 Würzburg, Germany
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Zhou Z, Sayed N, Pyriochou A, Roussos C, Fulton D, Beuve A, Papapetropoulos A. Protein kinase G phosphorylates soluble guanylyl cyclase on serine 64 and inhibits its activity. Arterioscler Thromb Vasc Biol 2008; 28:1803-10. [PMID: 18635821 DOI: 10.1161/atvbaha.108.165043] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Binding of nitric oxide (NO) to soluble guanylyl cyclase (sGC) leads to increased cGMP synthesis that activates cGMP-dependent protein kinase (PKG). Herein, we tested whether sGC activity is regulated by PKG. METHODS AND RESULTS Overexpression of a constitutively active form of PKG (DeltaPKG) stimulated (32)P incorporation into the alpha1 subunit. Serine to alanine mutation of putative sites revealed that Ser64 is the main phosphorylation site for PKG. Using a phospho-specific antibody we observed that endogenous sGC phosphorylation on Ser 64 increases in cells and tissues exposed to NO, in a PKG-inhibitable manner. Wild-type (wt) sGC coexpressed with DeltaPKG exhibited lower basal and NO-stimulated cGMP accumulation, whereas the S64A alpha1/beta1 sGC was resistant to the PKG-induced reduction in activity. Using purified sGC we observed that the S64D alpha1 phosphomimetic /beta1 dimer exhibited lower Vmax; moreover, the decrease in Km after NO stimulation was less pronounced in S64D alpha1/beta1 compared to wild-type sGC. Expression of a phosphorylation-deficient sGC showed enhanced responsiveness to endothelium-derived NO, reduced desensitization to acute NO exposure, and allowed for greater VASP phosphorylation. CONCLUSIONS We conclude that PKG phosphorylates sGC on Ser64 of the alpha1 subunit and that phosphorylation inhibits sGC activity, establishing a negative feedback loop.
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Affiliation(s)
- Zongmin Zhou
- Critical Care Department, Evangelismos Hospital, University of Athens School of Medicine, Greece
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Rentsendorj O, Mirzapoiazova T, Adyshev D, Servinsky LE, Renné T, Verin AD, Pearse DB. Role of vasodilator-stimulated phosphoprotein in cGMP-mediated protection of human pulmonary artery endothelial barrier function. Am J Physiol Lung Cell Mol Physiol 2008; 294:L686-97. [PMID: 18281604 DOI: 10.1152/ajplung.00417.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increased pulmonary endothelial cGMP was shown to prevent endothelial barrier dysfunction through activation of protein kinase G (PKG(I)). Vasodilator-stimulated phosphoprotein (VASP) has been hypothesized to mediate PKG(I) barrier protection because VASP is a cytoskeletal phosphorylation target of PKG(I) expressed in cell-cell junctions. Unphosphorylated VASP was proposed to increase paracellular permeability through actin polymerization and stress fiber bundling, a process inhibited by PKG(I)-mediated phosphorylation of Ser(157) and Ser(239). To test this hypothesis, we examined the role of VASP in the transient barrier dysfunction caused by H(2)O(2) in human pulmonary artery endothelial cell (HPAEC) monolayers studied without and with PKG(I) expression introduced by adenoviral infection (Ad.PKG). In the absence of PKG(I) expression, H(2)O(2) (100-250 microM) caused a transient increased permeability and pSer(157)-VASP formation that were both attenuated by protein kinase C inhibition. Potentiation of VASP Ser(157) phosphorylation by either phosphatase 2B inhibition with cyclosporin or protein kinase A activation with forskolin prolonged, rather than inhibited, the increased permeability caused by H(2)O(2). With Ad.PKG infection, inhibition of VASP expression with small interfering RNA exacerbated H(2)O(2)-induced barrier dysfunction but had no effect on cGMP-mediated barrier protection. In addition, expression of a Ser-double phosphomimetic mutant VASP failed to reproduce the protective effects of activated PKG(I). Finally, expression of a Ser-double phosphorylation-resistant VASP failed to interfere with the ability of cGMP/PKG(I) to attenuate H(2)O(2)-induced disruption of VE-cadherin homotypic binding. Our results suggest that VASP phosphorylation does not explain the protective effect of cGMP/PKG(I) on H(2)O(2)-induced endothelial barrier dysfunction in HPAEC.
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Affiliation(s)
- Otgonchimeg Rentsendorj
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD 21224, USA
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Abstract
The actin cytoskeleton is required for many important processes during embryonic development. In later stages of life, important homeostatic processes depend on the actin cytoskeleton, such as immune response, haemostasis and blood vessel preservation. Therefore, the function of the actin cytoskeleton must be tightly regulated, and aberrant regulation may cause disease. A growing number of proteins have been described to bind and regulate the actin cytoskeleton. Amongst them, Ena/VASP proteins function as anti-capping proteins, thereby directly modulating the actin ultrastructure. Ena/VASP function is regulated by their recruitment into protein complexes downstream of plasma membrane receptors and by phosphorylation. As regulators of the actin ultrastructure, Ena/VASP proteins are involved in crucial cellular functions, such as shape change, adhesion, migration and cell-cell interaction and hence are important targets for therapeutic intervention. In this chapter, we will first describe the structure, function and regulation of Ena/VASP proteins. Then, we will review the involvement of Ena/VASP proteins in the development of human diseases. Growing evidence links Ena/VASP proteins to important human diseases, such as thrombosis, cancer, arteriosclerosis, cardiomyopathy and nephritis. Finally, present and future perspectives for the development of therapeutic molecules interfering with Ena/VASP-mediated protein-protein interactions are presented.
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Affiliation(s)
- G Pula
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London, UK
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Chen H, Levine YC, Golan DE, Michel T, Lin AJ. Atrial natriuretic peptide-initiated cGMP pathways regulate vasodilator-stimulated phosphoprotein phosphorylation and angiogenesis in vascular endothelium. J Biol Chem 2007; 283:4439-47. [PMID: 18079117 DOI: 10.1074/jbc.m709439200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Nitric oxide (NO)- and atrial natriuretic peptide (ANP)-initiated cGMP signaling cascades are important in the maintenance of cardiovascular homeostasis. The molecular signaling mechanisms downstream of cGMP are not well understood, however. We have used small interfering RNA (siRNA) approaches to specifically knock down a series of signaling proteins in bovine aortic endothelial cells, and we have combined biochemical analyses with physiological assays to investigate cGMP-mediated signal transduction pathways. Activation of particulate guanylate cyclase (GC-A) by ANP leads to a substantial, dose-dependent, rapid, and sustained increase in intracellular cGMP. In contrast, stimulation of soluble guanylate cyclase by NO yields only a weak and transient increase in cGMP. ANP-induced cGMP production is selectively suppressed by siRNA-mediated knockdown of GC-A. ANP greatly enhances the phosphorylation at Ser-239 of the vasodilator-stimulated phosphoprotein (VASP), a major substrate of cGMP-dependent protein kinase (PKG) that significantly influences actin dynamics. Moreover, the ANP-induced phosphorylation of VASP at Ser-239 is accompanied by increased actin stress fiber formation and enhanced endothelial tube formation. siRNA-mediated knockdown of GC-A, VASP, or PKG abolishes ANP-induced VASP Ser-239 phosphorylation, stress fiber formation, and endothelial tube formation. We have demonstrated similar findings in human umbilical vein endothelial cells, where ANP substantially enhances intracellular cGMP content, phosphorylation of VASP at Ser-239, and endothelial tube formation. Taken together, our findings suggest that ANP-mediated cGMP signal transduction pathways regulate PKG phosphorylation of VASP Ser-239 in endothelial cells, resulting in reorganization of the actin cytoskeleton and enhancement of angiogenesis.
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Affiliation(s)
- Hongjie Chen
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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