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PI3Kγ stimulates a high molecular weight form of myosin light chain kinase to promote myeloid cell adhesion and tumor inflammation. Nat Commun 2022; 13:1768. [PMID: 35365657 PMCID: PMC8975949 DOI: 10.1038/s41467-022-29471-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 03/16/2022] [Indexed: 02/07/2023] Open
Abstract
Myeloid cells play key roles in cancer immune suppression and tumor progression. In response to tumor derived factors, circulating monocytes and granulocytes extravasate into the tumor parenchyma where they stimulate angiogenesis, immune suppression and tumor progression. Chemokines, cytokines and interleukins stimulate PI3Kγ-mediated Rap1 activation, leading to conformational changes in integrin α4β1 that promote myeloid cell extravasation and tumor inflammation Here we show that PI3Kγ activates a high molecular weight form of myosin light chain kinase, MLCK210, that promotes myosin-dependent Rap1 GTP loading, leading to integrin α4β1 activation. Genetic or pharmacological inhibition of MLCK210 suppresses integrin α4β1 activation, as well as tumor inflammation and progression. These results demonstrate a critical role for myeloid cell MLCK210 in tumor inflammation and serve as basis for the development of alternative approaches to develop immune oncology therapeutics. Myeloid cell recruitment during tumor inflammation depends on the VCAM-1 receptor integrin α4β1. Here the authors show that a high molecular weight form of myosin light chain kinase, MLCK210, is required for myeloid cell integrin α4β1 activation and adhesion and that MLCK210 inhibition reduces tumor growth and inflammation in preclinical cancer models.
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Srivastava N, Tauseef M, Amin R, Joshi B, Joshi JC, Kini V, Klomp J, Li W, Knezevic N, Barbera N, Siddiqui S, Obukhov A, Karginov A, Levitan I, Komarova Y, Mehta D. Noncanonical function of long myosin light chain kinase in increasing ER-PM junctions and augmentation of SOCE. FASEB J 2020; 34:12805-12819. [PMID: 32772419 PMCID: PMC7496663 DOI: 10.1096/fj.201902462rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 06/26/2020] [Accepted: 07/16/2020] [Indexed: 12/13/2022]
Abstract
Increased endothelial permeability leads to excessive exudation of plasma proteins and leukocytes in the interstitium, which characterizes several vascular diseases including acute lung injury. The myosin light chain kinase long (MYLK-L) isoform is canonically known to regulate the endothelial permeability by phosphorylating myosin light chain (MLC-P). Compared to the short MYLK isoform, MYLK-L contains an additional stretch of ~919 amino acid at the N-terminus of unknown function. We show that thapsigargin and thrombin-induced SOCE was markedly reduced in Mylk-L-/- endothelial cells (EC) or MYLK-L-depleted human EC. These agonists also failed to increase endothelial permeability in MYLK-L-depleted EC and Mylk-L-/- lungs, thus demonstrating the novel role of MYLK-L-induced SOCE in increasing vascular permeability. MYLK-L augmented SOCE by increasing endoplasmic reticulum (ER)-plasma membrane (PM) junctions and STIM1 translocation to these junctions. Transduction of N-MYLK domain (amino acids 1-919 devoid of catalytic activity) into Mylk-L-/- EC rescued SOCE to the level seen in control EC in a STIM1-dependent manner. N-MYLK-induced SOCE augmented endothelial permeability without MLC-P via an actin-binding motif, DVRGLL. Liposomal-mediated delivery of N-MYLK mutant but not ∆DVRGLL-N-MYLK mutant in Mylk-L-/- mice rescued vascular permeability increase in response to endotoxin, indicating that targeting of DVRGLL motif within MYLK-L may limit SOCE-induced vascular hyperpermeability.
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Affiliation(s)
- Nityanand Srivastava
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Mohammad Tauseef
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
- Department of Pharmaceutical SciencesChicago State University College of PharmacyChicagoILUSA
| | - Ruhul Amin
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Bhagwati Joshi
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Jagdish Chandra Joshi
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Vidisha Kini
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Jennifer Klomp
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Weenan Li
- Department of Cellular and Integrative PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - Nebojsa Knezevic
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Nicolas Barbera
- Department of MedicineThe Uniiversity of IllinoisChicagoILUSA
| | - Shahid Siddiqui
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Alexander Obukhov
- Department of Cellular and Integrative PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - Andrei Karginov
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Irena Levitan
- Department of MedicineThe Uniiversity of IllinoisChicagoILUSA
| | - Yulia Komarova
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
| | - Dolly Mehta
- Department of Pharmacology and Center for Lung and Vascular BiologyThe University of Illinois, College of MedicineChicagoILUSA
- Department of Pharmaceutical SciencesChicago State University College of PharmacyChicagoILUSA
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3
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Kelley CA, Wirshing ACE, Zaidel-Bar R, Cram EJ. The myosin light-chain kinase MLCK-1 relocalizes during Caenorhabditis elegans ovulation to promote actomyosin bundle assembly and drive contraction. Mol Biol Cell 2018; 29:1975-1991. [PMID: 30088798 PMCID: PMC6232974 DOI: 10.1091/mbc.e18-01-0056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
We identify the Caenorhabditis elegans myosin light-chain kinase, MLCK-1, required for contraction of spermathecae. During contraction, MLCK-1 moves from the apical cell boundaries to the basal actomyosin bundles, where it stabilizes myosin downstream of calcium signaling. MLCK and ROCK act in distinct subsets of cells to coordinate the timing of contraction.
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Affiliation(s)
| | | | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Erin J Cram
- Department of Biology, Northeastern University, Boston, MA 02115
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Impact of Atherosclerosis- and Diabetes-Related Dicarbonyls on Vascular Endothelial Permeability: A Comparative Assessment. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1625130. [PMID: 29098058 PMCID: PMC5643129 DOI: 10.1155/2017/1625130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/31/2017] [Accepted: 09/10/2017] [Indexed: 12/05/2022]
Abstract
Background Malondialdehyde (MDA), glyoxal (GO), and methylglyoxal (MGO) levels increase in atherosclerosis and diabetes patients. Recent reports demonstrate that GO and MGO cause vascular endothelial barrier dysfunction whereas no evidence is available for MDA. Methods To compare the effects of MDA, GO, or MGO on endothelial permeability, we used human EA.hy926 endothelial cells as a standard model. To study cortical cytoplasm motility and cytoskeletal organization in endothelial cells, we utilized time-lapse microscopy and fluorescent microscopy. To compare dicarbonyl-modified protein band profiles in these cells, we applied Western blotting with antibodies against MDA- or MGO-labelled proteins. Results MDA (150–250 μM) irreversibly suppressed the endothelial cell barrier, reduced lamellipodial activity, and prevented intercellular contact formation. The motile deficiency of MDA-challenged cells was accompanied by alterations in microtubule and microfilament organization. These detrimental effects were not observed after GO or MGO (250 μM) administration regardless of confirmed modification of cellular proteins by MGO. Conclusions Our comparative study demonstrates that MDA is more damaging to the endothelial barrier than GO or MGO. Considering that MDA endogenous levels exceed those of GO or MGO and tend to increase further during lipoperoxidation, it appears important to reduce oxidative stress and, in particular, MDA levels in order to prevent sustained vascular hyperpermeability in atherosclerosis and diabetes patients.
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Baumann F, Bauer MS, Rees M, Alexandrovich A, Gautel M, Pippig DA, Gaub HE. Increasing evidence of mechanical force as a functional regulator in smooth muscle myosin light chain kinase. eLife 2017; 6. [PMID: 28696205 PMCID: PMC5505704 DOI: 10.7554/elife.26473] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/20/2017] [Indexed: 11/18/2022] Open
Abstract
Mechanosensitive proteins are key players in cytoskeletal remodeling, muscle contraction, cell migration and differentiation processes. Smooth muscle myosin light chain kinase (smMLCK) is a member of a diverse group of serine/threonine kinases that feature cytoskeletal association. Its catalytic activity is triggered by a conformational change upon Ca2+/calmodulin (Ca2+/CaM) binding. Due to its significant homology with the force-activated titin kinase, smMLCK is suspected to be also regulatable by mechanical stress. In this study, a CaM-independent activation mechanism for smMLCK by mechanical release of the inhibitory elements is investigated via high throughput AFM single-molecule force spectroscopy. The characteristic pattern of transitions between different smMLCK states and their variations in the presence of different substrates and ligands are presented. Interaction between kinase domain and regulatory light chain (RLC) substrate is identified in the absence of CaM, indicating restored substrate-binding capability due to mechanically induced removal of the auto-inhibitory regulatory region. DOI:http://dx.doi.org/10.7554/eLife.26473.001
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Affiliation(s)
- Fabian Baumann
- Chair for Applied Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Magnus Sebastian Bauer
- Chair for Applied Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.,Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Martin Rees
- Randall Division of Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, London, United Kingdom
| | - Alexander Alexandrovich
- Randall Division of Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, London, United Kingdom
| | - Mathias Gautel
- Randall Division of Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, London, United Kingdom
| | - Diana Angela Pippig
- Chair for Applied Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Hermann Eduard Gaub
- Chair for Applied Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany
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Khapchaev AY, Shirinsky VP. Myosin Light Chain Kinase MYLK1: Anatomy, Interactions, Functions, and Regulation. BIOCHEMISTRY (MOSCOW) 2017; 81:1676-1697. [PMID: 28260490 DOI: 10.1134/s000629791613006x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This review discusses and summarizes the results of molecular and cellular investigations of myosin light chain kinase (MLCK, MYLK1), the key regulator of cell motility. The structure and regulation of a complex mylk1 gene and the domain organization of its products is presented. The interactions of the mylk1 gene protein products with other proteins and posttranslational modifications of the mylk1 gene protein products are reviewed, which altogether might determine the role and place of MLCK in physiological and pathological reactions of cells and entire organisms. Translational potential of MLCK as a drug target is evaluated.
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Affiliation(s)
- A Y Khapchaev
- Russian Cardiology Research and Production Center, Moscow, 121552, Russia.
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7
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Gaceb A, Vergori L, Martinez MC, Andriantsitohaina R. Activation of Endothelial Pro-resolving Anti-Inflammatory Pathways by Circulating Microvesicles from Non-muscular Myosin Light Chain Kinase-Deficient Mice. Front Pharmacol 2016; 7:322. [PMID: 27708581 PMCID: PMC5030219 DOI: 10.3389/fphar.2016.00322] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/05/2016] [Indexed: 11/13/2022] Open
Abstract
Microvesicles, small membrane vesicles released from cells, have beneficial and/or deleterious effects in sepsis. We previously reported that non-muscle myosin light chain kinase (nmMLCK) deletion protects mice against endotoxic shock by reducing inflammation. Here, we have evaluated the consequences of nmMLCK deletion on microvesicle phenotypes and their effects on mouse aortic endothelial cells in association with vascular inflammation and endothelial dysfunction during endotoxic shock induced by lipopolysaccharide in mice. Treatment with lipopolysaccharide induced an increase in levels of circulating microvesicles in wild type but not in nmMLCK-deficient mice. Microvesicles from nmMLCK-deficient mice (MVsnmMLCK-/-) prevented the inflammatory effects of lipopolysaccharide with concomitant increase of anti- inflammatory and reduction of pro-inflammatory secretome in mouse aortic endothelial cells. In addition, MVsnmMLCK-/- reduced the efficacy of lipopolysaccharide to increase aortic oxidative and nitrosative stresses as well as macrophage infiltration in the aorta. Moreover, MVsnmMLCK-/- prevented ex vivo endothelial dysfunction, vascular hyporeactivity, and in vivo overproduction of nitric oxide in heart and liver in response to lipopolysaccharide. Altogether, these findings provide evidence that nmMLCK deletion generates circulating microvesicles displaying protective effects by activating endothelial pro-resolving anti-inflammatory pathways allowing the effective down-regulation of oxidative and nitrative stresses associated with endotoxic shock. Thus, nmMLCK plays a pivotal role in susceptibility to sepsis via the control of cellular activation and release of circulating microvesicles.
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Affiliation(s)
| | - Luisa Vergori
- INSERM U1063, Université d'AngersAngers, France; Centre Hospitalo-Universitaire d'AngersAngers, France
| | - M C Martinez
- INSERM U1063, Université d'AngersAngers, France; Centre Hospitalo-Universitaire d'AngersAngers, France
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Vilitkevich EL, Khapchaev AY, Kudryashov DS, Nikashin AV, Schavocky JP, Lukas TJ, Watterson DM, Shirinsky VP. Phosphorylation Regulates Interaction of 210-kDa Myosin Light Chain Kinase N-terminal Domain with Actin Cytoskeleton. BIOCHEMISTRY (MOSCOW) 2016; 80:1288-97. [PMID: 26567572 DOI: 10.1134/s0006297915100090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High molecular weight myosin light chain kinase (MLCK210) is a multifunctional protein involved in myosin II activation and integration of cytoskeletal components in cells. MLCK210 possesses actin-binding regions both in the central part of the molecule and in its N-terminal tail domain. In HeLa cells, mitotic protein kinase Aurora B was suggested to phosphorylate MLCK210 N-terminal tail at serine residues (Dulyaninova, N. G., and Bresnick, A. R. (2004) Exp. Cell Res., 299, 303-314), but the functional significance of the phosphorylation was not established. We report here that in vitro, the N-terminal actin-binding domain of MLCK210 is located within residues 27-157 (N27-157, avian MLCK210 sequence) and is phosphorylated by cAMP-dependent protein kinase (PKA) and Aurora B at serine residues 140/149 leading to a decrease in N27-157 binding to actin. The same residues are phosphorylated in a PKA-dependent manner in transfected HeLa cells. Further, in transfected cells, phosphomimetic mutants of N27-157 showed reduced association with the detergent-stable cytoskeleton, whereas in vitro, the single S149D mutation reduced N27-157 association with F-actin to a similar extent as that achieved by N27-157 phosphorylation. Altogether, our results indicate that phosphorylation of MLCK210 at distinct serine residues, mainly at S149, attenuates the interaction of MLCK210 N-terminus with the actin cytoskeleton and might serve to regulate MLCK210 microfilament cross-linking activity in cells.
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Affiliation(s)
- E L Vilitkevich
- Russian Cardiology Research and Production Center, Moscow, 121552, Russia.
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9
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Sundararajan V, Gengenbacher N, Stemmler MP, Kleemann JA, Brabletz T, Brabletz S. The ZEB1/miR-200c feedback loop regulates invasion via actin interacting proteins MYLK and TKS5. Oncotarget 2016; 6:27083-96. [PMID: 26334100 PMCID: PMC4694975 DOI: 10.18632/oncotarget.4807] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 08/07/2015] [Indexed: 02/06/2023] Open
Abstract
Epithelial to mesenchymal transition (EMT) is a developmental process which is aberrantly activated during cancer invasion and metastasis. Elevated expression of EMT-inducers like ZEB1 enables tumor cells to detach from the primary tumor and invade into the surrounding tissue. The main antagonist of ZEB1 in controlling EMT is the microRNA-200 family that is reciprocally linked to ZEB1 in a double negative feedback loop. Here, we further elucidate how the ZEB1/miR-200 feedback loop controls invasion of tumor cells. The process of EMT is attended by major changes in the actin cytoskeleton. Via in silico screening of genes encoding for actin interacting proteins, we identified two novel targets of miR-200c - TKS5 and MYLK (MLCK). Co-expression of both genes with ZEB1 was observed in several cancer cell lines as well as in breast cancer patients and correlated with low miR-200c levels. Depletion of TKS5 or MYLK in breast cancer cells reduced their invasive potential and their ability to form invadopodia. Whereas TKS5 is known to be a major component, we could identify MYLK as a novel player in invadopodia formation. In summary, TKS5 and MYLK represent two mediators of invasive behavior of cancer cells that are regulated by the ZEB1/miR-200 feedback loop.
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Affiliation(s)
- Vignesh Sundararajan
- Department of Visceral Surgery, University Medical Center Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, Freiburg, Germany.,Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Nicolas Gengenbacher
- Division of Vascular Oncology and Metastasis, German Cancer Research Center (DKFZ-ZMBH Alliance), Heidelberg, Germany
| | - Marc P Stemmler
- Department of Experimental Medicine I, Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, Erlangen, Germany
| | - Julia A Kleemann
- Department of Experimental Medicine I, Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, Erlangen, Germany
| | - Thomas Brabletz
- Department of Experimental Medicine I, Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, Erlangen, Germany
| | - Simone Brabletz
- Department of Experimental Medicine I, Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, Erlangen, Germany
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10
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Interaction in endothelium of non-muscular myosin light-chain kinase and the NF-κB pathway is critical to lipopolysaccharide-induced vascular hyporeactivity. Clin Sci (Lond) 2015. [PMID: 26201020 DOI: 10.1042/cs20140625] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During sepsis, endothelial barrier dysfunction contributes to cardiovascular failure, mainly through the release of oxidative metabolites by penetrant leukocytes. We reported the non-muscular isoform of myosin light chain kinase (nmMLCK) playing a pivotal role in endotoxin shock injury associated with oxidative and nitrative stresses, and vascular hyporeactivity. The present study was aimed at understanding the molecular mechanism of lipopolysaccharide (LPS)-induced vascular alterations as well as studying a probable functional association of nmMLCK with nuclear factor κ-light-chain enhancer of activated B cells (NF-κB). Aortic rings from mice were exposed in vitro to LPS and, then, vascular reactivity was measured. Human aortic endothelial cells (HAoECs) were incubated with LPS, and interaction of nmMLCK with NF-κB was analysed. We provide evidence that nmMLCK deletion prevents vascular hyporeactivity induced by in vitro LPS treatment but not endothelial dysfunction in the aorta. Deletion of nmMLCK inhibits LPS-induced NF-κB activation and increases nitric oxide (NO) release via induction of inducible NO synthase (iNOS) within the vascular wall. Also, removal of endothelium prevented both NF-κB and iNOS expression in aortic rings. Among the proinflammatory factors released by LPS-treated endothelial cells, interleukin-6 accounts for the induction of iNOS on smooth muscle cells in response to LPS. Of particular interest is the demonstration that, in HAoECs, LPS-induced NF-κB activation occurs via increased MLCK activity sensitive to the MLCK inhibitor, ML-7, and physical interactions between nmMLCK and NF-κB. We report for the first time on NF-κB as a novel partner of nmMLCK within endothelial cells. The present study demonstrates a pivotal role of nmMLCK in vascular inflammatory pathologies.
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11
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Rossi JL, Todd T, Bazan NG, Belayev L. Inhibition of Myosin light-chain kinase attenuates cerebral edema after traumatic brain injury in postnatal mice. J Neurotrauma 2013; 30:1672-9. [PMID: 23984869 DOI: 10.1089/neu.2013.2898] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Traumatic brain injury (TBI) in children less than 8 years of age leads to decline in intelligence and executive functioning. Neurological outcomes after TBI correlate to development of cerebral edema, which affect survival rates after TBI. It has been shown that myosin light-chain kinase (MLCK) increases cerebral edema and that pretreatment with an MLCK inhibitor (ML-7) reduces cerebral edema. The aim of this study was to determine whether inhibition of MLCK after TBI in postnatal day 24 (PND-24) mice would prevent breakdown of the blood-brain barrier (BBB) and development of cerebral edema and improve neurological outcome. We used a closed head injury model of TBI. ML-7 or saline treatment was administered at 4 h and every 24 h until sacrifice or 5 days after TBI. Mice were sacrificed at 24 h, 48 h, and 72 h and 7 days after impact. Mice treated with ML-7 after TBI had decreased levels of MLCK-expressing cells (20.7±4.8 vs. 149.3±40.6), less albumin extravasation (28.3±11.2 vs. 116.2±60.7 mm(2)) into surrounding parenchymal tissue, less Evans Blue extravasation (339±314 vs. 4017±560 ng/g), and showed a significant difference in wet/dry weight ratio (1.9±0.07 vs. 2.2±0.05 g), compared to saline-treated groups. Treatment with ML-7 also resulted in preserved neurological function measured by the wire hang test (57 vs. 21 sec) and two-object novel recognition test (old vs. new, 10.5 touches). We concluded that inhibition of MLCK reduces cerebral edema and preserves neurological function in PND-24 mice.
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Affiliation(s)
- Janet L Rossi
- 1 Neuroscience Center of Excellence, Louisiana State University Health Sciences Center , New Orleans, Louisiana
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12
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Gautel M. Cytoskeletal protein kinases: titin and its relations in mechanosensing. Pflugers Arch 2011; 462:119-34. [PMID: 21416260 PMCID: PMC3114093 DOI: 10.1007/s00424-011-0946-1] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 12/22/2022]
Abstract
Titin, the giant elastic ruler protein of striated muscle sarcomeres, contains a catalytic kinase domain related to a family of intrasterically regulated protein kinases. The most extensively studied member of this branch of the human kinome is the Ca2+–calmodulin (CaM)-regulated myosin light-chain kinases (MLCK). However, not all kinases of the MLCK branch are functional MLCKs, and about half lack a CaM binding site in their C-terminal autoinhibitory tail (AI). A unifying feature is their association with the cytoskeleton, mostly via actin and myosin filaments. Titin kinase, similar to its invertebrate analogue twitchin kinase and likely other “MLCKs”, is not Ca2+–calmodulin-activated. Recently, local protein unfolding of the C-terminal AI has emerged as a common mechanism in the activation of CaM kinases. Single-molecule data suggested that opening of the TK active site could also be achieved by mechanical unfolding of the AI. Mechanical modulation of catalytic activity might thus allow cytoskeletal signalling proteins to act as mechanosensors, creating feedback mechanisms between cytoskeletal tension and tension generation or cellular remodelling. Similar to other MLCK-like kinases like DRAK2 and DAPK1, TK is linked to protein turnover regulation via the autophagy/lysosomal system, suggesting the MLCK-like kinases have common functions beyond contraction regulation.
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Affiliation(s)
- Mathias Gautel
- King's College London BHF Centre of Research Excellence, Cardiovascular Division, London, SE1 1UL, UK.
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13
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Rossi JL, Ralay Ranaivo H, Patel F, Chrzaszcz M, Venkatesan C, Wainwright MS. Albumin causes increased myosin light chain kinase expression in astrocytes via p38 mitogen-activated protein kinase. J Neurosci Res 2011; 89:852-61. [PMID: 21360574 DOI: 10.1002/jnr.22600] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 12/30/2022]
Abstract
Myosin light chain kinase (MLCK) plays an important role in the reorganization of the cytoskeleton, leading to disruption of vascular barrier integrity in multiple organs, including the blood-brain barrier (BBB), after traumatic brain injury (TBI). MLCK has been linked to transforming growth factor (TGF) and rho kinase signaling pathways, but the mechanisms regulating MLCK expression following TBI are not well understood. Albumin leaks into the brain parenchyma following TBI, activates glia, and has been linked to TGF-β receptor signaling. We investigated the role of albumin in the increase of MLCK in astrocytes and the signaling pathways involved in this increase. After midline closed-skull TBI in mice, there was a significant increase in MLCK-immunoreactive (IR) cells and albumin extravasation, which was prevented by treatment with the MLCK inhibitor ML-7. Using immunohistochemical methods, we identified the MLCK-IR cells as astrocytes. In primary astrocytes, exposure to albumin increased both isoforms of MLCK, 130 and 210. Inhibition of the TGF-β receptor partially prevented the albumin-induced increase in both isoforms, which was not prevented by inhibition of smad3. Inhibition of p38 MAPK, but not ERK, JNK, or rho kinase, also prevented this increase. These results are further evidence of a role of MLCK in the mechanisms of BBB compromise following TBI and identify astrocytes as a cell type, in addition to endothelium in the BBB, that expresses MLCK. These findings implicate albumin, acting through p38 MAPK, in a novel mechanism by which activation of MLCK following TBI may lead to compromise of the BBB.
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Affiliation(s)
- Janet L Rossi
- Department of Pediatrics, Divisions of Critical Care, Children's Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60614, USA
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Thatcher SE, Fultz ME, Tanaka H, Hagiwara H, Zhang HL, Zhang Y, Hayakawa K, Yoshiyama S, Nakamura A, Wang HH, Katayama T, Watanabe M, Lin Y, Wright GL, Kohama K. Myosin Light Chain Kinase / Actin Interaction in Phorbol Dibutyrate–Stimulated Smooth Muscle Cells. J Pharmacol Sci 2011; 116:116-27. [DOI: 10.1254/jphs.10296fp] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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15
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Chavez A, Smith M, Mehta D. New Insights into the Regulation of Vascular Permeability. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 290:205-48. [DOI: 10.1016/b978-0-12-386037-8.00001-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Miao H, Crabb AW, Hernandez MR, Lukas TJ. Modulation of factors affecting optic nerve head astrocyte migration. Invest Ophthalmol Vis Sci 2010; 51:4096-103. [PMID: 20375339 DOI: 10.1167/iovs.10-5177] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE The authors investigated the role of myosin light chain kinase (MYLK) and transforming growth factor beta (TGFbeta) receptor pathways in optic nerve head (ONH) astrocyte migration. They further investigated how the expression of these genes is altered by elevated hydrostatic pressure (HP). METHODS PCR was used to determine the isoforms of MYLK expressed in ONH astrocytes. siRNAs against MYLK (all isoforms) and TGFbeta receptor 2 (TGFBR2) were prepared and tested for effects on the migration of cultured ONH astrocytes. Finally, the effects of elevated HP (24-96 hours) on the expression of MYLK isoforms and selected TGFbeta pathway components were measured. RESULTS Multiple isoforms of MYLK are present in ONH astrocytes from Caucasian (CA) and African American (AA) donors. Both populations express the short form (MYLK-130) and the long form (MYLK-210) of MYLK and a splicing variant within MYLK-210. MYLK-directed siRNA decreased MYLK expression and cell migration compared with control siRNA. siRNA directed against TGFbeta receptor 2 also decreased cell migration compared with control and decreased extracellular matrix genes regulated by TGFbeta signaling. Elevated HP increased the expression of MYLK-130 and MYLK-210 in both populations of astrocytes. However, TGFbeta2 was uniquely upregulated by exposure to elevated HP in CA compared with AA astrocytes. CONCLUSIONS Differential expression of TGFbeta pathway genes and MYLK isoforms observed in populations of glaucomatous astrocytes applies to the elevated HP model system. MYLK may be a new target for intervention in glaucoma to alter reactive astrocyte migration in the ONH.
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Affiliation(s)
- Haixi Miao
- Department of Ophthalmology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
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17
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Lukas TJ, Miao H, Chen L, Riordan SM, Li W, Crabb AM, Wise A, Du P, Lin SM, Hernandez MR. Susceptibility to glaucoma: differential comparison of the astrocyte transcriptome from glaucomatous African American and Caucasian American donors. Genome Biol 2008; 9:R111. [PMID: 18613964 PMCID: PMC2530868 DOI: 10.1186/gb-2008-9-7-r111] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 06/18/2008] [Accepted: 07/09/2008] [Indexed: 12/23/2022] Open
Abstract
Comparison of gene expression in normal and glaucomatous eyes from Caucasian American and African American donors reveals differences that might reflect different susceptibility to glaucoma. Background Epidemiological and genetic studies indicate that ethnic/genetic background plays an important role in susceptibility to primary open angle glaucoma (POAG). POAG is more prevalent among the African-descent population compared to the Caucasian population. Damage in POAG occurs at the level of the optic nerve head (ONH) and is mediated by astrocytes. Here we investigated differences in gene expression in primary cultures of ONH astrocytes obtained from age-matched normal and glaucomatous donors of Caucasian American (CA) and African American (AA) populations using oligonucleotide microarrays. Results Gene expression data were obtained from cultured astrocytes representing 12 normal CA and 12 normal AA eyes, 6 AA eyes with POAG and 8 CA eyes with POAG. Data were normalized and significant differential gene expression levels detected by using empirical Bayesian shrinkage moderated t-statistics. Gene Ontology analysis and networks of interacting proteins were constructed using the BioGRID database. Network maps included regulation of myosin, actin, and protein trafficking. Real-time RT-PCR, western blots, ELISA, and functional assays validated genes in the networks. Conclusion Cultured AA and CA glaucomatous astrocytes retain differential expression of genes that promote cell motility and migration, regulate cell adhesion, and are associated with structural tissue changes that collectively contribute to neural degeneration. Key upregulated genes include those encoding myosin light chain kinase (MYLK), transforming growth factor-β receptor 2 (TGFBR2), rho-family GTPase-2 (RAC2), and versican (VCAN). These genes along with other differentially expressed components of integrated networks may reflect functional susceptibility to chronic elevated intraocular pressure that is enhanced in the optic nerve head of African Americans.
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Affiliation(s)
- Thomas J Lukas
- Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University, E Chicago Ave, Chicago, IL 60611, USA.
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18
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Xu J, Gao XP, Ramchandran R, Zhao YY, Vogel SM, Malik AB. Nonmuscle myosin light-chain kinase mediates neutrophil transmigration in sepsis-induced lung inflammation by activating beta2 integrins. Nat Immunol 2008; 9:880-6. [PMID: 18587400 DOI: 10.1038/ni.1628] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Accepted: 05/29/2008] [Indexed: 11/09/2022]
Abstract
Nonmuscle myosin light-chain kinase (MYLK) mediates increased lung vascular endothelial permeability in lipopolysaccharide-induced lung inflammatory injury, the chief cause of the acute respiratory distress syndrome. In a lung injury model, we demonstrate here that MYLK was also essential for neutrophil transmigration, but that this function was mostly independent of myosin II regulatory light chain, the only known substrate of MYLK. Instead, MYLK in neutrophils was required for the recruitment and activation of the tyrosine kinase Pyk2, which mediated full activation of beta(2) integrins. Our results demonstrate that MYLK-mediated activation of beta(2) integrins through Pyk2 links beta(2) integrin signaling to the actin motile machinery of neutrophils.
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Affiliation(s)
- Jingsong Xu
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
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19
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Moitra J, Evenoski C, Sammani S, Wadgaonkar R, Turner JR, Ma SF, Garcia JGN. A transgenic mouse with vascular endothelial over-expression of the non-muscle myosin light chain kinase-2 isoform is susceptible to inflammatory lung injury: role of sexual dimorphism and age. Transl Res 2008; 151:141-53. [PMID: 18279813 PMCID: PMC2693047 DOI: 10.1016/j.trsl.2007.12.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 12/10/2007] [Accepted: 12/11/2007] [Indexed: 01/11/2023]
Abstract
We have generated genetically engineered mice that are uniquely susceptible to lipopolysaccharide (LPS)-induced and mechanical ventilation-induced lung injury in a sex-specific and age-specific manner. These mice express a nonmuscle isoform of the myosin light chain kinase gene (nmMLCK2) targeted to the endothelium. Homozygous mice have significantly reduced fecundity and litter survival until weaning, and they are initially growth delayed but eventually exceed the size of wild-type littermates. Mice at all ages show increased protein transport across the lung barrier; however, the phenotype is most discernible in 8-12-week-old male mice. When subjected to a clinically relevant LPS-induced lung injury model, 8-12-week-old young females and 30-36-week-old males seem to be the most significantly injured group. In contrast, 30-36-week-old males remain the most significantly injured group when mechanically ventilated at high tidal volumes, which is a clinically relevant model of mechanical stress lung injury. These data reveal that nmMLCK2 overexpression in the endothelium exacerbates lung injury in vivo in a sexually dimorphic and age-dependent manner.
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Affiliation(s)
- Jaideep Moitra
- Department of Medicine, University of Chicago, Chicago, Il 60637-1470, USA
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20
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Takizawa N, Ikebe R, Ikebe M, Luna EJ. Supervillin slows cell spreading by facilitating myosin II activation at the cell periphery. J Cell Sci 2007; 120:3792-803. [DOI: 10.1242/jcs.008219] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
During cell migration, myosin II modulates adhesion, cell protrusion and actin organization at the leading edge. We show that an F-actin- and membrane-associated scaffolding protein, called supervillin (SV, p205), binds directly to the subfragment 2 domains of nonmuscle myosin IIA and myosin IIB and to the N-terminus of the long form of myosin light chain kinase (L-MLCK). SV inhibits cell spreading via an MLCK- and myosin II-dependent mechanism. Overexpression of SV reduces the rate of cell spreading, and RNAi-mediated knockdown of endogenous SV increases it. Endogenous and EGFP-tagged SV colocalize with, and enhance the formation of, cortical bundles of F-actin and activated myosin II during early cell spreading. The effects of SV are reversed by inhibition of myosin heavy chain (MHC) ATPase (blebbistatin), MLCK (ML-7) or MEK (U0126), but not by inhibiting Rho-kinase with Y-27632. Flag-tagged L-MLCK co-localizes in cortical bundles with EGFP-SV, and kinase-dead L-MLCK disorganizes these bundles. The L-MLCK- and myosin-binding site in SV, SV1-171, rearranges and co-localizes with mono- and di-phosphorylated myosin light chain and with L-MLCK, but not with the short form of MLCK (S-MLCK) or with myosin phosphatase. Thus, the membrane protein SV apparently contributes to myosin II assembly during cell spreading by modulating myosin II regulation by L-MLCK.
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Affiliation(s)
- Norio Takizawa
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Cell Dynamics Program, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Reiko Ikebe
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Cell Dynamics Program, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Mitsuo Ikebe
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Cell Dynamics Program, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Elizabeth J. Luna
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Cell Dynamics Program, University of Massachusetts Medical School, Worcester, MA 01605, USA
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Ralay Ranaivo H, Carusio N, Wangensteen R, Ohlmann P, Loichot C, Tesse A, Chalupsky K, Lobysheva I, Haiech J, Watterson DM, Andriantsitohaina R. Protection against endotoxic shock as a consequence of reduced nitrosative stress in MLCK210-null mice. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:439-46. [PMID: 17255312 PMCID: PMC1851870 DOI: 10.2353/ajpath.2007.060219] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study investigated the consequences of deletion of the long isoform of myosin light chain kinase (MLCK210) on the cardiovascular changes induced by the bacterial endotoxin lipopolysaccharide (LPS) and cecal ligation puncture using MLCK210-/- mice. Here, we provide evidence that deletion of MLCK210 enhanced survival after intraperitoneal injection of LPS or cecal ligation puncture. LPS-induced vascular hyporeactivity to vasoconstrictor agents was completely prevented in aorta from MLCK210-/- mice. This was associated with a decreased up-regulation of nuclear facor-kappaB expression and activity, inducible nitric-oxide synthase, and level of oxidative stress in the vascular media. Furthermore, LPS-induced increase of nitric oxide production in the circulation and tissues (including heart, liver, and lung) that was correlated with an increased expression of inducible nitric-oxide synthase was also reduced in MLCK210-/- mice. These data demonstrate a role for MLCK210 in endotoxin shock injury associated with oxidative and nitrosative stresses and vascular hyporeactivity.
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22
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Dudnakova TV, Stepanova OV, Dergilev KV, Chadin AV, Shekhonin BV, Watterson DM, Shirinsky VP. Myosin light chain kinase colocalizes with nonmuscle myosin IIB in myofibril precursors and sarcomeric Z-lines of cardiomyocytes. ACTA ACUST UNITED AC 2006; 63:375-83. [PMID: 16634081 DOI: 10.1002/cm.20127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Myosin light chain kinase (MLCK) is a key regulator of various forms of cell motility involving actin and myosin II. MLCK is widely present in vertebrate tissues including the myocardium. However, the role of MLCK in cardiomyocyte function is not known. Previous attempts to gain insight into possible roles and identify potential molecular partners were disappointing and equivocal due to cross reactivity of early antibodies with striated muscle MLCK, which has a different genetic locus and a divergent amino acid sequence from the above mentioned enzyme. Using an immunofluorescence approach and a panel of antibodies directed against MLCK, cytoskeletal, and sarcomeric proteins, we localized MLCK to myofibril precursors and Z-lines of sarcomeres in embryonic and adult cardiomyocytes. The same structures contained nonmuscle myosin IIB implicating this protein as a possible target of MLCK. Our results suggest a role for MLCK in cardiomyocyte differentiation and contraction through regulation of nonmuscle myosin IIB.
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Affiliation(s)
- T V Dudnakova
- Laboratory of Cell Motility, Russian Cardiology Research Center, Moscow, Russia
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23
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Yang CX, Chen HQ, Chen C, Yu WP, Zhang WC, Peng YJ, He WQ, Wei DM, Gao X, Zhu MS. Microfilament-binding properties of N-terminal extension of the isoform of smooth muscle long myosin light chain kinase. Cell Res 2006; 16:367-76. [PMID: 16617332 DOI: 10.1038/sj.cr.7310047] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Myosin light chain kinases (MLCK) phosphorylate the regulatory light chain of myosin II in thick filaments and bind to F-actin-containing thin filaments with high affinity. The ability of short myosin light chain kinase (S-MLCK) to bind F-actin is structurally attributed to the DFRXXL regions in its N-terminus. The long myosin light chain kinase (L-MLCK) has two additional DFRXXL motifs and six Ig-like modules in its N-terminal extension. The six Ig-like modules are capable of binding to stress fibers independently. Our results from the imaging analysis demonstrated that the first two intact Ig-like modules (2Ig) in N-terminal extension of L-MLCK is the minimal binding module required for microfilament binding. Binding assay confirmed that F-actin was able to bind 2Ig. Stoichiometries of 2Ig peptide were similar for myofilament or pure F-actin. The binding affinities were slightly lower than 5DFRXXL peptide as reported previously. Similar to DFRXXL peptides, the 2Ig peptide also caused efficient F-actin bundle formation in vitro. In the living cell, over-expression of 2Ig fragment increased "spike"-like protrusion formation with over-bundled F-actin. Our results suggest that L-MLCK may act as a potent F-actin bundling protein via its DFRXXL region and the 2Ig region, implying that L-MLCK plays a role in cytoskeleton organization.
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Affiliation(s)
- Chun Xiang Yang
- Model Animal Research Center and National Key Lab of Medicine, Nanjing University, Nanjing 210061, China
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24
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Ohlmann P, Tesse A, Loichot C, Ralay Ranaivo H, Roul G, Philippe C, Watterson DM, Haiech J, Andriantsitohaina R. Deletion of MLCK210 induces subtle changes in vascular reactivity but does not affect cardiac function. Am J Physiol Heart Circ Physiol 2005; 289:H2342-9. [PMID: 16055522 DOI: 10.1152/ajpheart.00511.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myosin light chain kinase (MLCK) plays a key role in the regulation of actomyosin contraction in a large variety of cells. Two isoforms have been described: a short isoform, widely expressed in smooth muscle cells; and a long isoform (MLCK210), mainly localized in the endothelium. This study investigated the consequences on different cardiovascular parameters of MLCK210 gene deletion using MLCK210 knockout mice and of pharmacological inhibition of the kinase using a specific MLCK inhibitor. Deletion of MLCK210 did not affect systolic blood pressure and heart rate or echocardiographic measurements. Electrocardiographic analysis showed neither atrio- nor intraventricular conduction or repolarization defects. Ex vivo responses of aortic rings to vasoconstrictor and vasodilator agonists were not modified in MLCK210 null mice. However, deletion of MLCK210 attenuated shear stress-induced dilation and produced changes in the balance of endothelial-relaxing factors of small mesenteric arteries (SMA). In particular, a reduced flow-mediated NO-dependent dilation was observed. However, it was partially compensated by enhanced indomethacin-sensitive dilation. No significant changes were detected in the endothelium-derived hyperpolarizing component of the vasodilator response. The above effects of MLCK210 gene deletion were confirmed in SMA from wild-type mice by the use of the MLCK enzymatic inhibitor MMZ-10-057. In summary, deletion of MLCK210 was not associated with abnormalities of main in vivo cardiovascular parameters in mice. This study demonstrates a role for MLCK210 in the regulation of flow-dependent dilation in SMA.
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Affiliation(s)
- Patrick Ohlmann
- UMR CNRS 7034, Faculté de Pharmacie, 74, route du Rhin, 67401 Illkirch, France
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25
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Diecke FP, Wen Q, Iserovich P, Li J, Kuang K, Fischbarg J. Regulation of Na-K-2Cl cotransport in cultured bovine corneal endothelial cells. Exp Eye Res 2005; 80:777-85. [PMID: 15939033 DOI: 10.1016/j.exer.2004.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 11/23/2004] [Accepted: 12/08/2004] [Indexed: 11/16/2022]
Abstract
We have previously demonstrated the presence of a Na(+)-K(+)-2Cl cotransporter in cultured bovine corneal endothelial cells (CBCEC) and determined that this cotransporter is located in the basolateral membrane. This transporter may contribute to volume regulation and transendothelial fluid transport. We have now investigated factors regulating the activity of the cotransporter. This activity was assessed by measuring the bumetanide-sensitive (86)Rubidium ((86)Rb) uptake in (86)Rb-containing solutions. Data were normalized to protein content determined with a Lowry protein assay. We investigated the regulation by extracellular and intracellular ion concentrations, by osmotic gradients, and by second messengers. Our results indicate that extracellular Na+ and K+ each are required for activation of the cotransporter and activate with first-order kinetics at half-maximally effective concentrations (k(1/2)) of 21.1 and 1.33 mM, respectively. Extracellular Cl- is also required for cotransport activation, but shows higher order kinetics; the k(1/2) for Cl- is 28.1 mM and the Hill coefficient 2.1. HCO(3)(-) exerts a modulating effect on cotransporter activity; at 0 HCO(3)(-) the bumetanide-sensitive K(+) uptake is reduced by 30% compared to that at 26 mm HCO(3)(-). Manipulations of the intracellular [Cl-] by preincubation in Cl- -free solution or inhibition of Cl- efflux resulted in increased uptake at low [Cl-](i) and decreased uptake at high [Cl-](i). To assess the role of protein kinases in the regulation of cotransport, we have determined the effect of protein kinase inhibitors. H-89 and KT5270, inhibitors of PKA, inhibit cotransport almost completely, while calphostin C, an inhibitor of PKC, produces a small activation of cotransport. The tyrosine kinase inhibitor genistein reduced K+ uptake while its inactive analog daidzein was without effect. The calmodulin kinase inhibitor KN-93 was without effect. We also investigated the effects of phosphatase inhibitors. Calyculin A (k(1/2)=21 nM) and okadaic acid (k(1/2)=915 nM) produced approximate doubling of K+ uptake, suggesting that phosphatase 1 is dominant. We also investigated the role of the cytoskeleton and its activation. Reduction of Ca(i)(2+) by preincubation in Ca2+ -free medium as well as by exposure to W-7, an inhibitor of the binding of Ca(2+) to calmodulin, reduced K+ uptake. Consistent with this, ML-7, a relatively specific inhibitor of the Ca2+ -calmodulin activated myosin light chain kinase, inhibited cotransport by 40%. The Ca2+ -calmodulin activated myosin light chain kinase contributes to the modulation of the cytoskeleton by regulating the actin-myosin interaction. Consistent with the above, disruption of the actin polymerization by cytochalasin D led to a decrease in K+ uptake. We conclude that extracellular Na+, K+ and Cl- are requirements for the function of the CBCEC Na(+)-K(+)-2Cl(-) cotransporter, while intracellular Cl- and extracellular HCO(3)(-) modulate its activity. Several protein kinases, including PKA, PKC, tyrosine kinase, and myosin light chain kinase, modulate the K+ uptake. Another modulating pathway for cotransport involves the state of the cytoskeleton.
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Affiliation(s)
- Friedrich P Diecke
- Department of Physiology and Pharmacology, UMDNJ-New Jersey Medical School, Newark, NJ 07103-2714, USA
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26
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Xia D, Stull JT, Kamm KE. Myosin phosphatase targeting subunit 1 affects cell migration by regulating myosin phosphorylation and actin assembly. Exp Cell Res 2004; 304:506-17. [PMID: 15748895 DOI: 10.1016/j.yexcr.2004.11.025] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 11/22/2004] [Accepted: 11/22/2004] [Indexed: 11/20/2022]
Abstract
Myosin II plays important roles in many contractile-like cell functions, including cell migration, adhesion, and retraction. Myosin II is activated by regulatory light chain (RLC) phosphorylation whereas RLC dephosphorylation by myosin light chain phosphatase containing a myosin phosphatase targeting subunit (MYPT1) leads to myosin inactivation. HeLa cells contain MYPT1 in addition to a newly identified human variant 2 containing an internal deletion. RLC dephosphorylation, cell migration, and adhesion were inhibited when either or both MYPT1 isoforms were knocked down by RNA interference. RLC was highly phosphorylated (60%) when both isoforms were suppressed by siRNA treatment relative to control cells (10%) with serum-starvation and ROCK inhibition. Prominent stress fibers and focal adhesions were associated with the enhanced RLC phosphorylation. The reintroduction of MYPT1 or variant 2 in siRNA-treated cells decreased stress fibers and focal adhesions. MYPT1 knockdown also led to an increase of F-actin relative to G-actin in HeLa cells. The myosin inhibitor blebbistatin did not inhibit this effect, indicating MYPT1 likely affects actin assembly independent of RLC phosphorylation. Proper expression of MYPT1 or variant 2 is critical for RLC phosphorylation and actin assembly, thus maintaining normal cellular functions by simultaneously controlling cytoskeletal architecture and actomyosin activation.
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Affiliation(s)
- Donglan Xia
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040, USA.
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