51
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Soriano-Castell D, Chavero A, Rentero C, Bosch M, Vidal-Quadras M, Pol A, Enrich C, Tebar F. ROCK1 is a novel Rac1 effector to regulate tubular endocytic membrane formation during clathrin-independent endocytosis. Sci Rep 2017; 7:6866. [PMID: 28761175 PMCID: PMC5537229 DOI: 10.1038/s41598-017-07130-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 06/23/2017] [Indexed: 01/10/2023] Open
Abstract
Clathrin-dependent and -independent pathways contribute for β1-integrin endocytosis. This study defines a tubular membrane clathrin-independent endocytic network, induced with the calmodulin inhibitor W13, for β1-integrin internalization. This pathway is dependent on increased phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) levels and dynamin activity at the plasma membrane. Exogenous addition of PI(4,5)P2 or phosphatidylinositol-4-phosphate 5-kinase (PIP5K) expression mimicked W13-generated-tubules which are inhibited by active Rac1. Therefore, the molecular mechanisms downstream of Rac1, that controls this plasma membrane tubulation, were analyzed biochemically and by the expression of different Rac1 mutants. The results indicate that phospholipase C and ROCK1 are the main Rac1 effectors that impair plasma membrane invagination and tubule formation, essentially by decreasing PI(4,5)P2 levels and promoting cortical actomyosin assembly respectively. Interestingly, among the plethora of proteins that participate in membrane remodeling, this study revealed that ROCK1, the well-known downstream RhoA effector, has an important role in Rac1 regulation of actomyosin at the cell cortex. This study provides new insights into Rac1 functioning on plasma membrane dynamics combining phosphatidylinositides and cytoskeleton regulation.
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Affiliation(s)
- David Soriano-Castell
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Albert Chavero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Marta Bosch
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Maite Vidal-Quadras
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Albert Pol
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036, Barcelona, Spain.
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52
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Takaki T, Montagner M, Serres MP, Le Berre M, Russell M, Collinson L, Szuhai K, Howell M, Boulton SJ, Sahai E, Petronczki M. Actomyosin drives cancer cell nuclear dysmorphia and threatens genome stability. Nat Commun 2017; 8:16013. [PMID: 28737169 PMCID: PMC5527285 DOI: 10.1038/ncomms16013] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 05/24/2017] [Indexed: 12/16/2022] Open
Abstract
Altered nuclear shape is a defining feature of cancer cells. The mechanisms underlying nuclear dysmorphia in cancer remain poorly understood. Here we identify PPP1R12A and PPP1CB, two subunits of the myosin phosphatase complex that antagonizes actomyosin contractility, as proteins safeguarding nuclear integrity. Loss of PPP1R12A or PPP1CB causes nuclear fragmentation, nuclear envelope rupture, nuclear compartment breakdown and genome instability. Pharmacological or genetic inhibition of actomyosin contractility restores nuclear architecture and genome integrity in cells lacking PPP1R12A or PPP1CB. We detect actin filaments at nuclear envelope rupture sites and define the Rho-ROCK pathway as the driver of nuclear damage. Lamin A protects nuclei from the impact of actomyosin activity. Blocking contractility increases nuclear circularity in cultured cancer cells and suppresses deformations of xenograft nuclei in vivo. We conclude that actomyosin contractility is a major determinant of nuclear shape and that unrestrained contractility causes nuclear dysmorphia, nuclear envelope rupture and genome instability.
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Affiliation(s)
- Tohru Takaki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Marco Montagner
- Tumour Cell Biology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Murielle P. Serres
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Maël Le Berre
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005 Paris, France
| | - Matt Russell
- Electron Microscopy Group, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Lucy Collinson
- Electron Microscopy Group, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Karoly Szuhai
- Department of Molecular Cell Biology, LUMC, Einthovenweg 20, 2333 ZC Leiden, The Netherlands
| | - Michael Howell
- High Throughput Screening Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Simon J. Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Erik Sahai
- Tumour Cell Biology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Mark Petronczki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- Boehringer Ingelheim RCV GmbH & Co KG, Dr Boehringer Gasse 5-11, A-1121 Vienna, Austria
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53
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Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology. J Physiol Sci 2017; 68:1-17. [PMID: 28681362 PMCID: PMC5754374 DOI: 10.1007/s12576-017-0556-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 06/27/2017] [Indexed: 12/26/2022]
Abstract
Protein phosphatases 1 and 2A (PP1 and PP2A) are the most ubiquitous and abundant serine/threonine phosphatases in eukaryotic cells. They play fundamental roles in the regulation of various cellular functions. This review focuses on recent advances in the functional studies of these enzymes in the field of smooth muscle physiology. Many naturally occurring protein phosphatase inhibitors with different relative PP1/PP2A affinities have been discovered and are widely used as powerful research tools. Current topics in the chemical biology of PP1/PP2A inhibitors are introduced and discussed, highlighting the identification of the gene cluster responsible for the biosynthesis of calyculin A in a symbiont microorganism of a marine sponge.
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54
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Mathiassen SG, De Zio D, Cecconi F. Autophagy and the Cell Cycle: A Complex Landscape. Front Oncol 2017; 7:51. [PMID: 28409123 PMCID: PMC5374984 DOI: 10.3389/fonc.2017.00051] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/10/2017] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a self-degradation pathway, in which cytoplasmic material is sequestered in double-membrane vesicles and delivered to the lysosome for degradation. Under basal conditions, autophagy plays a homeostatic function. However, in response to various stresses, the pathway can be further induced to mediate cytoprotection. Defective autophagy has been linked to a number of human pathologies, including neoplastic transformation, even though autophagy can also sustain the growth of tumor cells in certain contexts. In recent years, a considerable correlation has emerged between autophagy induction and stress-related cell-cycle responses, as well as unexpected roles for autophagy factors and selective autophagic degradation in the process of cell division. These advances have obvious implications for our understanding of the intricate relationship between autophagy and cancer. In this review, we will discuss our current knowledge of the reciprocal regulation connecting the autophagy pathway and cell-cycle progression. Furthermore, key findings involving nonautophagic functions for autophagy-related factors in cell-cycle regulation will be addressed.
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Affiliation(s)
- Søs Grønbæk Mathiassen
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Daniela De Zio
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Francesco Cecconi
- Cell Stress and Survival Unit, Danish Cancer Society Research Center, Copenhagen, Denmark.,Department of Biology, University of Rome Tor Vergata, Rome, Italy.,Department of Pediatric Hematology and Oncology, Istituto di Ricovero e Cura a Carattere Scientifico Bambino Gesù Children's Hospital, Rome, Italy
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55
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Myosin phosphatase and RhoA-activated kinase modulate arginine methylation by the regulation of protein arginine methyltransferase 5 in hepatocellular carcinoma cells. Sci Rep 2017; 7:40590. [PMID: 28074910 PMCID: PMC5225440 DOI: 10.1038/srep40590] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 12/08/2016] [Indexed: 12/25/2022] Open
Abstract
Myosin phosphatase (MP) holoenzyme is a protein phosphatase-1 (PP1) type Ser/Thr specific enzyme that consists of a PP1 catalytic (PP1c) and a myosin phosphatase target subunit-1 (MYPT1). MYPT1 is an ubiquitously expressed isoform and it targets PP1c to its substrates. We identified the protein arginine methyltransferase 5 (PRMT5) enzyme of the methylosome complex as a MYPT1-binding protein uncovering the nuclear MYPT1-interactome of hepatocellular carcinoma cells. It is shown that PRMT5 is regulated by phosphorylation at Thr80 by RhoA-associated protein kinase and MP. Silencing of MYPT1 increased the level of the PRMT5-specific symmetric dimethylation on arginine residues of histone 2 A/4, a repressing gene expression mark, and it resulted in a global change in the expression of genes affecting cellular processes like growth, proliferation and cell death, also affecting the expression of the retinoblastoma protein and c-Myc. The phosphorylation of the MP inhibitory MYPT1T850 and the regulatory PRMT5T80 residues as well as the symmetric dimethylation of H2A/4 were elevated in human hepatocellular carcinoma and in other types of cancers. These changes correlated positively with the grade and state of the tumors. Our results suggest the tumor suppressor role of MP via inhibition of PRMT5 thereby regulating gene expression through histone arginine dimethylation.
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56
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The protective role of MLCP-mediated ERM dephosphorylation in endotoxin-induced lung injury in vitro and in vivo. Sci Rep 2016; 6:39018. [PMID: 27976727 PMCID: PMC5157034 DOI: 10.1038/srep39018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 11/17/2016] [Indexed: 12/13/2022] Open
Abstract
The goal of this study was to investigate the role of MLC phosphatase (MLCP) in a LPS model of acute lung injury (ALI). We demonstrate that ectopic expression of a constitutively-active (C/A) MLCP regulatory subunit (MYPT1) attenuates the ability of LPS to increase endothelial (EC) permeability. Down-regulation of MYPT1 exacerbates LPS-induced expression of ICAM1 suggesting an anti-inflammatory role of MLCP. To determine whether MLCP contributes to LPS-induced ALI in vivo, we utilized a nanoparticle DNA delivery method to specifically target lung EC. Expression of a C/A MYPT1 reduced LPS-induced lung inflammation and vascular permeability. Further, increased expression of the CS1β (MLCP catalytic subunit) also reduced LPS-induced lung inflammation, whereas the inactive CS1β mutant increased vascular leak. We next examined the role of the cytoskeletal targets of MLCP, the ERM proteins (Ezrin/Radixin/Moesin), in mediating barrier dysfunction. LPS-induced increase in EC permeability was accompanied by PKC-mediated increase in ERM phosphorylation, which was more prominent in CS1β-depleted cells. Depletion of Moesin and Ezrin, but not Radixin attenuated LPS-induced increases in permeability. Further, delivery of a Moesin phospho-null mutant into murine lung endothelium attenuated LPS-induced lung inflammation and vascular leak suggesting that MLCP opposes LPS-induced ALI by mediating the dephosphorylation of Moesin and Ezrin.
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57
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Myosin phosphatase Fine-tunes Zebrafish Motoneuron Position during Axonogenesis. PLoS Genet 2016; 12:e1006440. [PMID: 27855159 PMCID: PMC5147773 DOI: 10.1371/journal.pgen.1006440] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 10/21/2016] [Indexed: 01/30/2023] Open
Abstract
During embryogenesis the spinal cord shifts position along the anterior-posterior axis relative to adjacent tissues. How motor neurons whose cell bodies are located in the spinal cord while their axons reside in adjacent tissues compensate for such tissue shift is not well understood. Using live cell imaging in zebrafish, we show that as motor axons exit from the spinal cord and extend through extracellular matrix produced by adjacent notochord cells, these cells shift several cell diameters caudally. Despite this pronounced shift, individual motoneuron cell bodies stay aligned with their extending axons. We find that this alignment requires myosin phosphatase activity within motoneurons, and that mutations in the myosin phosphatase subunit mypt1 increase myosin phosphorylation causing a displacement between motoneuron cell bodies and their axons. Thus, we demonstrate that spinal motoneurons fine-tune their position during axonogenesis and we identify the myosin II regulatory network as a key regulator.
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58
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Wang Z, Ma B, Li H, Xiao X, Zhou W, Liu F, Zhang B, Zhu M, Yang Q, Zeng Y, Sun Y, Sun S, Wang Y, Zhang Y, Weng H, Chen L, Ye M, An X, Liu J. Protein 4.1N acts as a potential tumor suppressor linking PP1 to JNK-c-Jun pathway regulation in NSCLC. Oncotarget 2016; 7:509-23. [PMID: 26575790 PMCID: PMC4808014 DOI: 10.18632/oncotarget.6312] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 11/02/2015] [Indexed: 12/15/2022] Open
Abstract
Protein 4.1N is a member of protein 4.1 family and has been recognized as a potential tumor suppressor in solid tumors. Here, we aimed to investigate the role and mechanisms of 4.1N in non-small cell lung cancer (NSCLC). We confirmed that the expression level of 4.1N was inversely correlated with the metastatic properties of NSCLC cell lines and histological grade of clinical NSCLC tissues. Specific knockdown of 4.1N promoted tumor cell proliferation, migration and adhesion in vitro, and tumor growth and metastasis in mouse xenograft models. Furthermore, we identified PP1 as a novel 4.1N-interacting molecule, and the FERM domain of 4.1N mediated the interaction between 4.1N and PP1. Further, ectopic expression of 4.1N could inactivate JNK-c-Jun signaling pathway through enhancing PP1 activity and interaction between PP1 and p-JNK. Correspondingly, expression of potential downstream metastasis targets (ezrin and MMP9) and cell cycle targets (p53, p21 and p19) of JNK-c-Jun pathway were also regulated by 4.1N. Our data suggest that down-regulation of 4.1N expression is a critical step for NSCLC development and that repression of JNK-c-Jun signaling through PP1 is one of the key anti-tumor mechanisms of 4.1N.
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Affiliation(s)
- Zi Wang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China.,Department of Medicine, University of California, Irvine, CA, USA
| | - Bianyin Ma
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Hui Li
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Xiaojuan Xiao
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Weihua Zhou
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China.,Department of Biochemistry, College of Medicine, Jishou University, Jishou, China
| | - Feng Liu
- Department of Medicine, University of California, Irvine, CA, USA
| | - Bin Zhang
- Department of Histology and Embryology, Xiangya School of Medicine, Central South University, Changsha, China
| | - Min Zhu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Qin Yang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yayue Zeng
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yang Sun
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University, Changsha, China
| | - Shuming Sun
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yanpeng Wang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yibin Zhang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Haibo Weng
- College of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Lixiang Chen
- College of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Mao Ye
- Molecular Science and Biomedicine Laboratory, State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University, Changsha, China
| | - Xiuli An
- College of Life Sciences, Zhengzhou University, Zhengzhou, China.,Laboratory of Membrane Biology, New York Blood Center, New York, NY, USA
| | - Jing Liu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
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59
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Liu L, Chen L, Mai Z, Peng Z, Yu K, Liu G, Ai H. Cyclical compressive stress induces differentiation of rat primary mandibular condylar chondrocytes through phosphorylated myosin light chain II. Mol Med Rep 2016; 14:4293-4300. [PMID: 27748856 DOI: 10.3892/mmr.2016.5788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 09/05/2016] [Indexed: 11/05/2022] Open
Abstract
The role of myosin light chain II (MLC‑II) in cellular differentiation of rat mandibular condylar chondrocytes (MCCs) induced by cyclical uniaxial compressive stress (CUCS) remains unclear. In the current study, a four‑point bending system was used to apply CUCS to primary cultured MCCs from rats. It was identified that CUCS stimulated features of cellular differentiation including morphological alterations, cytoskeleton rearrangement and overproduction of proteoglycans. Furthermore, CUCS promoted runt‑related transcription factor‑2 (RUNX2) expression at mRNA (P<0.01) and protein levels (P<0.05) and elevated alkaline phosphatase (ALP) activity (P<0.01), which are both markers of osteogenic differentiation. Under conditions of stress, western blotting indicated that the ratio of phosphorylated MLC‑II to total MLC‑II was increased significantly (P<0.05). Silencing MLC‑II by RNA interference reduced ALP activity (P<0.01), and eliminated RUNX2 mRNA expression (P<0.01). Addition of the MLC kinase inhibitor, ML‑7, reduced the CUCS‑associated upregulation of RUNX2 expression (P<0.01) and ALP activity (P<0.01). The data indicated that CUCS promoted cellular differentiation of rat primary MCCs, and this was suggested to be via the phosphorylation of MLC‑II.
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Affiliation(s)
- Limin Liu
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Lin Chen
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Zhihui Mai
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Zhuli Peng
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Kafung Yu
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Guanqi Liu
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Hong Ai
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
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60
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Al-Ghabkari A, Deng JT, McDonald PC, Dedhar S, Alshehri M, Walsh MP, MacDonald JA. A novel inhibitory effect of oxazol-5-one compounds on ROCKII signaling in human coronary artery vascular smooth muscle cells. Sci Rep 2016; 6:32118. [PMID: 27573465 PMCID: PMC5004178 DOI: 10.1038/srep32118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/02/2016] [Indexed: 12/27/2022] Open
Abstract
The selectivity of (4Z)-2-(4-chloro-3-nitrophenyl)-4-(pyridin-3-ylmethylidene)-1,3-oxazol-5-one (DI) for zipper-interacting protein kinase (ZIPK) was previously described by in silico computational modeling, screening a large panel of kinases, and determining the inhibition efficacy. Our assessment of DI revealed another target, the Rho-associated coiled-coil-containing protein kinase 2 (ROCKII). In vitro studies showed DI to be a competitive inhibitor of ROCKII (Ki, 132 nM with respect to ATP). This finding was supported by in silico molecular surface docking of DI with the ROCKII ATP-binding pocket. Time course analysis of myosin regulatory light chain (LC20) phosphorylation catalyzed by ROCKII in vitro revealed a significant decrease upon treatment with DI. ROCKII signaling was investigated in situ in human coronary artery vascular smooth muscle cells (CASMCs). ROCKII down-regulation using siRNA revealed several potential substrates involved in smooth muscle contraction (e.g., LC20, Par-4, MYPT1) and actin cytoskeletal dynamics (cofilin). The application of DI to CASMCs attenuated LC20, Par-4, LIMK, and cofilin phosphorylations. Notably, cofilin phosphorylation was not significantly decreased with a novel ZIPK selective inhibitor (HS-38). In addition, CASMCs treated with DI underwent cytoskeletal changes that were associated with diminution of cofilin phosphorylation. We conclude that DI is not selective for ZIPK and is a potent inhibitor of ROCKII.
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Affiliation(s)
- Abdulhameed Al-Ghabkari
- Department of Biochemistry &Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Jing-Ti Deng
- Department of Biochemistry &Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Paul C McDonald
- Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10th Ave, Vancouver, BC, V5Z 1L3, Canada
| | - Shoukat Dedhar
- Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10th Ave, Vancouver, BC, V5Z 1L3, Canada
| | - Mana Alshehri
- Department of Biochemistry &Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Michael P Walsh
- Department of Biochemistry &Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
| | - Justin A MacDonald
- Department of Biochemistry &Molecular Biology, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, T2N 4Z6, Canada
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61
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MURC deficiency in smooth muscle attenuates pulmonary hypertension. Nat Commun 2016; 7:12417. [PMID: 27546070 PMCID: PMC4996946 DOI: 10.1038/ncomms12417] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 06/30/2016] [Indexed: 02/06/2023] Open
Abstract
Emerging evidence suggests that caveolin-1 (Cav1) is associated with pulmonary arterial hypertension. MURC (also called Cavin-4) is a member of the cavin family, which regulates caveolar formation and functions together with caveolins. Here, we show that hypoxia increased Murc mRNA expression in the mouse lung, and that Murc-null mice exhibited attenuation of hypoxia-induced pulmonary hypertension (PH) accompanied by reduced ROCK activity in the lung. Conditional knockout mice lacking Murc in smooth muscle also resist hypoxia-induced PH. MURC regulates the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) through Rho/ROCK signalling. Cav1 suppresses RhoA activity in PASMCs, which is reversed by MURC. MURC binds to Cav1 and inhibits the association of Cav1 with the active form of Gα13, resulting in the facilitated association of the active form of Gα13 with p115RhoGEF. These results reveal that MURC has a function in the development of PH through modulating Rho/ROCK signalling. MURC protein regulates the function of caveolae, the small invaginations of the plasma membrane in muscle cells. Here the authors show that by interacting with caveolin proteins, MURC affects RhoA/ROCK signalling and regulates proliferation and migration of pulmonary artery smooth muscle cells, suggesting a new target in therapy of pulmonary hypertension.
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62
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Li J, Wang R, Tang DD. Vimentin dephosphorylation at ser-56 is regulated by type 1 protein phosphatase in smooth muscle. Respir Res 2016; 17:91. [PMID: 27457922 PMCID: PMC4960799 DOI: 10.1186/s12931-016-0415-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 07/21/2016] [Indexed: 11/22/2022] Open
Abstract
Background The intermediate filament protein vimentin undergoes reversible phosphorylation and dephosphorylation at Ser-56, which plays an important role in regulating the contraction-relaxation cycles of smooth muscle. The protein phosphatases that mediate vimentin dephosphorylation in smooth muscle have not been previously investigated. Methods The associations of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) with vimentin in mouse tracheal rings was evaluated by co-immunoprecipitation. Lentivirus-mediated shRNA against PP1 was used to assess the role of PP1 in vimentin dephosphorylation and the vimentin-associated process in smooth muscle. Results Co-immunoprecipitation analysis showed that vimentin interacted with PP1, but barely with PP2A, in airway smooth muscle. Knockdown of PP1 by lentivirus-mediated shRNA increased the acetylcholine-induced vimentin phosphorylation and smooth muscle contraction. Because vimentin phosphorylation is able to modulate p130 Crk-associated substrate (p130CAS) and actin polymerization, we also evaluated the role of PP1 in the biological processes. Silencing of PP1 also enhanced the agonist-induced the dissociation of p130CAS from vimentin and F/G-actin ratios (an index of actin polymerization). However, PP1 knockdown did not affect c-Abl tyrosine phosphorylation, an important molecule that controls actin dynamics. Conclusions Taken together, these findings suggest that PP1 is a key protein serine/threonine phosphatase that controls vimentin Ser-56 dephosphorylation in smooth muscle. PP1 regulates actin polymerization by modulating the dissociation of p130CAS from vimentin, but not by affecting c-Abl tyrosine kinase.
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Affiliation(s)
- Jia Li
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, MC-8, Albany, New York, USA
| | - Ruping Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, MC-8, Albany, New York, USA
| | - Dale D Tang
- Department of Molecular and Cellular Physiology, Albany Medical College, 47 New Scotland Avenue, MC-8, Albany, New York, USA.
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Zhang Y, Kawamichi H, Kohama K, Nakamura A. Calcium-mediated regulation of recombinant hybrids of full-length Physarum myosin heavy chain with Physarum/scallop myosin light chains. Acta Biochim Biophys Sin (Shanghai) 2016; 48:536-43. [PMID: 27125976 DOI: 10.1093/abbs/gmw031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/21/2016] [Indexed: 11/14/2022] Open
Abstract
Physarum myosin is a Ca(2+)-binding protein and its activity is inhibited by Ca(2+) In the present study, to clarify the light chains (LCs) from the different species (Physarum and scallop) and to determine the specific Ca(2+)-regulated effects, we constructed hybrid myosins with a Physarum myosin heavy chain (Ph·HC) and Physarum and/or scallop myosin LCs, and examined Ca(2+)-mediated regulation of ATPases and motor activities. In these experiments, it was found that Ca(2+) inhibited motilities and ATPase activities of Physarum hybrid myosin with scallop regulatory light chain (ScRLC) and Physarum essential light chain (PhELC) but could not inhibit those of the Physarum hybrid myosin mutant Ph·HC/ScRLC/PhELC-3A which lacks Ca(2+)-binding ability, indicating that PhELC plays a critical role in Ca(2+)-mediated regulation of Physarum myosin. Furthermore, the effects of Ca(2+) on ATPase activities of Physarum myosin constructs are in the following order: Ph·HC/PhRLC/PhELC > Ph·HC/ScRLC/PhELC > Ph·HC/PhRLC/ScELC > Ph·HC/ScRLC/ScELC, suggesting that the presence of PhRLC and PhELC leads to the greatest Ca(2+) sensitivity of Physarum myosin. Although we did not observe the motilities of Physarum hybrid myosin Ph·HC/PhRLC/ScELC and Ph·HC/ScRLC/ScELC, our results suggest that Ca(2+)-binding to the PhELC may alter the flexibility of the regulatory domain and induce a 'closed' state, which may consequently prevent full activity and force generation.
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Affiliation(s)
- Ying Zhang
- Department of Molecular Physiology and Medical Bioregulation, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi 755-8505, Japan
| | - Hozumi Kawamichi
- Department of Molecular Pharmacology and Oncology, Faculty of Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Kazuhiro Kohama
- Research Institute of Pharmaceutical Sciences, Musashino University, Nishitokyo, Tokyo 202-8585, Japan
| | - Akio Nakamura
- Department of Molecular Pharmacology and Oncology, Faculty of Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
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Characterization of isoform expression and subcellular distribution of MYPT1 in intestinal epithelial cells. Gene 2016; 588:1-6. [PMID: 27129938 DOI: 10.1016/j.gene.2016.04.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 04/07/2016] [Accepted: 04/23/2016] [Indexed: 11/21/2022]
Abstract
The regulation of intestinal epithelial permeability requires phosphorylation of myosin regulatory light chain (MLC). The phosphorylation status of MLC is regulated by myosin light chain phosphatase (MLCP) activities. The activity of the catalytic subunit of MLCP (PP1cδ) toward MLC depends on its regulatory subunit (MYPT1). In this study, we revealed the presence of two MYPT1 isoforms, full length and variant 2 in human intestinal (Caco-2) epithelial cells and isolated intestinal epithelial cells (IECs) from mice. In confluent Caco-2 cells, MYPT1 was distributed at cell-cell contacts and colocalized with F-actin. These results suggest that MYPT1 isoforms are expressed in intestinal epithelial cells and MYPT1 may be involved in the regulation of intestinal epithelial barrier function.
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65
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Liu B, Lee YC, Alwaal A, Wang G, Banie L, Lin CS, Lin G, Lue TF. Carbachol-induced signaling through Thr696-phosphorylation of myosin phosphatase-targeting subunit 1 (MYPT1) in rat bladder smooth muscle cells. Int Urol Nephrol 2016; 48:1237-1242. [PMID: 27118568 DOI: 10.1007/s11255-016-1303-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 04/19/2016] [Indexed: 12/18/2022]
Abstract
PURPOSE Lines of evidence suggest that Rho-associated protein kinase (ROCK)-mediated myosin phosphatase-targeting subunit 1 (MYPT1) phosphorylation plays a central role in smooth muscle contraction. However, the physiological significance of MYPT1 phosphorylation at Thr696 catalyzed by ROCK in bladder smooth muscle remains controversial. We attempt to directly observe the quantitative protein expression of Rho A/ROCK and phosphorylation of MYPT1 at Thr696 after carbachol administration in rat bladder smooth muscle cells (RBMSCs). MATERIALS AND METHODS Primary cultured smooth muscle cells were obtained from rat bladders. The effects of both concentration and time-course induced by the muscarinic agonist carbachol were investigated by assessing the expression of Rho A/ROCK and MYPT1 phosphorylation at Thr696 using Western blot. RESULTS In the dose-course studies, carbachol showed significant increase in phosphorylation of MYPT1 at Thr696 (p-MYPT1) from concentrations of 15-100 μM based on Western blot results (p < 0.05, ANOVA test). In the time-course studies, treatment of cells with 15 μM of carbachol significantly enhanced the expression of p-MYPT1 from 3 to 15 h (p < 0.05, ANOVA test) and induced the expression of Rho A from 10 to 120 min (p < 0.05, ANOVA test). CONCLUSIONS Carbachol can induce the expression of ROCK pathway, leading to MYPT1 phosphorylation at Thr696 and thereby sustained RBSMCs contraction.
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Affiliation(s)
- Benchun Liu
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Yung-Chin Lee
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
- Department of Urology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Amjad Alwaal
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Guifang Wang
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Lia Banie
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Ching-Shwun Lin
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Guiting Lin
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA
| | - Tom F Lue
- Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, 400 Parnassus Ave., Ste A-610, San Francisco, CA, 94143-0738, USA.
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Perrino BA. Calcium Sensitization Mechanisms in Gastrointestinal Smooth Muscles. J Neurogastroenterol Motil 2016; 22:213-25. [PMID: 26701920 PMCID: PMC4819859 DOI: 10.5056/jnm15186] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 12/22/2014] [Indexed: 01/05/2023] Open
Abstract
An increase in intracellular Ca2+ is the primary trigger of contraction of gastrointestinal (GI) smooth muscles. However, increasing the Ca2+ sensitivity of the myofilaments by elevating myosin light chain phosphorylation also plays an essential role. Inhibiting myosin light chain phosphatase activity with protein kinase C-potentiated phosphatase inhibitor protein-17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation is considered to be the primary mechanism underlying myofilament Ca2+ sensitization. The relative importance of Ca2+ sensitization mechanisms to the diverse patterns of GI motility is likely related to the varied functional roles of GI smooth muscles. Increases in CPI-17 and MYPT1 phosphorylation in response to agonist stimulation regulate myosin light chain phosphatase activity in phasic, tonic, and sphincteric GI smooth muscles. Recent evidence suggests that MYPT1 phosphorylation may also contribute to force generation by reorganization of the actin cytoskeleton. The mechanisms responsible for maintaining constitutive CPI-17 and MYPT1 phosphorylation in GI smooth muscles are still largely unknown. The characteristics of the cell-types comprising the neuroeffector junction lead to fundamental differences between the effects of exogenous agonists and endogenous neurotransmitters on Ca2+ sensitization mechanisms. The contribution of various cell-types within the tunica muscularis to the motor responses of GI organs to neurotransmission must be considered when determining the mechanisms by which Ca2+ sensitization pathways are activated. The signaling pathways regulating Ca2+ sensitization may provide novel therapeutic strategies for controlling GI motility. This article will provide an overview of the current understanding of the biochemical basis for the regulation of Ca2+ sensitization, while also discussing the functional importance to different smooth muscles of the GI tract.
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Affiliation(s)
- Brian A Perrino
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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67
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Gao N, Chang AN, He W, Chen CP, Qiao YN, Zhu M, Kamm KE, Stull JT. Physiological signalling to myosin phosphatase targeting subunit-1 phosphorylation in ileal smooth muscle. J Physiol 2016; 594:3209-25. [PMID: 26847850 DOI: 10.1113/jp271703] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/21/2016] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS The extent of myosin regulatory light chain phosphorylation (RLC) necessary for smooth muscle contraction depends on the respective activities of Ca(2+) /calmodulin-dependent myosin light chain kinase and myosin light chain phosphatase (MLCP), which contains a regulatory subunit MYPT1 bound to the phosphatase catalytic subunit and myosin. MYPT1 showed significant constitutive T696 and T853 phosphorylation, which is predicted to inhibit MLCP activity in isolated ileal smooth muscle tissues, with additional phosphorylation upon pharmacological treatment with the muscarinic agonist carbachol. Electrical field stimulation (EFS), which releases ACh from nerves, increased force and RLC phosphorylation but not MYPT1 T696 or T853 phosphorylation. The conditional knockout of MYPT1 or the knockin mutation T853A in mice had no effect on the frequency-maximal force responses to EFS in isolated ileal tissues. Physiological RLC phosphorylation and force development in ileal smooth muscle depend on myosin light chain kinase and MLCP activities without changes in constitutive MYPT1 phosphorylation. ABSTRACT Smooth muscle contraction initiated by myosin regulatory light chain (RLC) phosphorylation is dependent on the relative activities of Ca(2+) /calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We have investigated the physiological role of the MLCP regulatory subunit MYPT1 in ileal smooth muscle in adult mice with (1) smooth muscle-specific deletion of MYPT1; (2) non-phosphorylatable MYPT1 containing a T853A knockin mutation; and (3) measurements of force and protein phosphorylation responses to cholinergic neurostimulation initiated by electric field stimulation. Isolated MYPT1-deficient tissues from MYPT1(SM-/-) mice contracted and relaxed rapidly with moderate differences in sustained responses to KCl and carbachol treatments and washouts, respectively. Similarly, measurements of regulatory proteins responsible for RLC phosphorylation during contractions also revealed moderate changes. There were no differences in contractile or RLC phosphorylation responses to carbachol between tissues from normal mice vs. MYPT1 T853A knockin mice. Quantitatively, there was substantial MYPT1 T696 and T853 phosphorylation in wild-type tissues under resting conditions, predicting a high extent of MLCP phosphatase inhibition. Reduced PP1cδ activity in MYPT1-deficient tissues may be similar to attenuated MLCP activity in wild-type tissues resulting from constitutively phosphorylated MYPT1. Electric field stimulation increased RLC phosphorylation and force development in tissues from wild-type mice without an increase in MYPT1 phosphorylation. Thus, physiological RLC phosphorylation and force development in ileal smooth muscle appear to be dependent on MLCK and MLCP activities without changes in constitutive MYPT1 phosphorylation.
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Affiliation(s)
- Ning Gao
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Audrey N Chang
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Weiqi He
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China.,Current address: Cambridge-Suda (CAM-SU) Genomic Resource Centre, Soochow University, Suzhou, China
| | - Cai-Ping Chen
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Yan-Ning Qiao
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Minsheng Zhu
- Model Animal Research Centre and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
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Wernike D, Chen Y, Mastronardi K, Makil N, Piekny A. Mechanical forces drive neuroblast morphogenesis and are required for epidermal closure. Dev Biol 2016; 412:261-77. [PMID: 26923492 DOI: 10.1016/j.ydbio.2016.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/24/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
Abstract
Tissue morphogenesis requires myosin-dependent events such as cell shape changes and migration to be coordinated between cells within a tissue, and/or with cells from other tissues. However, few studies have investigated the simultaneous morphogenesis of multiple tissues in vivo. We found that during Caenorhabditis elegans ventral enclosure, when epidermal cells collectively migrate to cover the ventral surface of the embryo, the underlying neuroblasts (neuronal precursor cells) also undergo morphogenesis. We found that myosin accumulates as foci along the junction-free edges of the ventral epidermal cells to form a ring, whose closure is myosin-dependent. We also observed the accumulation of myosin foci and the adhesion junction proteins E-cadherin and α-catenin in the underlying neuroblasts. Myosin may help to reorganize a subset of neuroblasts into a rosette-like pattern, and decrease their surface area as the overlying epidermal cells constrict. Since myosin is required in the neuroblasts for ventral enclosure, we propose that mechanical forces in the neuroblasts influence constriction of the overlying epidermal cells. In support of this model, disrupting neuroblast cell division or altering their fate influences myosin localization in the overlying epidermal cells. The coordination of myosin-dependent events and forces between cells in different tissues could be a common theme for coordinating morphogenetic events during metazoan development.
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Affiliation(s)
- Denise Wernike
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Yun Chen
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | | - Neetha Makil
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, Quebec, Canada.
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Interaction of Myosin Phosphatase Target Subunit (MYPT1) with Myosin Phosphatase-RhoA Interacting Protein (MRIP): A Role of Glutamic Acids in the Interaction. PLoS One 2015; 10:e0139875. [PMID: 26445108 PMCID: PMC4596477 DOI: 10.1371/journal.pone.0139875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 09/18/2015] [Indexed: 11/19/2022] Open
Abstract
Scaffold proteins bind to and functionally link protein members of signaling pathways. Interaction of the scaffold proteins, myosin phosphatase target subunit (MYPT1) and myosin phosphatase-RhoA interacting protein (MRIP), causes co-localization of myosin phosphatase and RhoA to actomyosin. To examine biophysical properties of interaction of MYPT1 with MRIP, we employed analytical ultracentrifugation and surface plasmon resonance. In regard to MRIP, its residues 724-837 are sufficient for the MYPT1/MRIP interaction. Moreover, MRIP binds to MYPT1 as either a monomer or a dimer. With respect to MYPT1, its leucine repeat region, LR (residues 991-1030) is sufficient to account for the MYPT1/MRIP interaction. Furthermore, point mutations that replace glutamic acids 998-1000 within LR reduced the binding affinity toward MRIP. This suggests that the glutamic acids of MYPT1 play an important role in the interaction.
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70
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Anderson CD, Kendig DM, Al-Qudah M, Mahavadi S, Murthy KS, Grider JR. Role of various kinases in muscarinic M3 receptor-mediated contraction of longitudinal muscle of rat colon. J Smooth Muscle Res 2015; 50:103-19. [PMID: 25891767 PMCID: PMC4862207 DOI: 10.1540/jsmr.50.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The longitudinal muscle layer in gut is the functional opponent to the circular muscle
layer during peristalsis. Differences in innervation of the layers allow for the
contraction of one layer concurrently with the relaxation of the other, enabling the
passage of gut contents in a controlled fashion. Differences in development have given the
cells of the two layers differences in receptor populations, membrane lipid handling, and
calcium handling profiles/behaviors. The contractile activity of the longitudinal muscle
is largely mediated by cholinergic neural input from myenteric plexus. Activation of
muscarinic receptors leads to rapid activation of several kinases including MLC kinase,
ERK1/2, CaMKII and Rho kinase. Phosphorylation of myosin light chain (MLC20) by
MLC kinase (MLCK) is a prerequisite for contraction in both circular and longitudinal
muscle cells. In rat colonic longitudinal muscle strips, we measured muscarinic
receptor-mediated contraction following incubation with kinase inhibitors. Basal tension
was differentially regulated by Rho kinase, ERK1/2, CaMKII and CaMKK. Selective inhibitors
of Rho kinase, ERK1/2, CaMKK/AMPK, and CaMKII each reduced carbachol-induced contraction
in the innervated muscle strips. These inhibitors had no direct effect on MLCK activity.
Thus unlike previously reported for isolated muscle cells where CaMKII and ERK1/2 are not
involved in contraction, we conclude that the regulation of carbachol-induced contraction
in innervated longitudinal muscle strips involves the interplay of Rho kinase, ERK1/2,
CaMKK/AMPK, and CAMKII.
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Affiliation(s)
- Charles D Anderson
- Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences, Virginia Commonwealth University, USA
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CRB3A Controls the Morphology and Cohesion of Cancer Cells through Ehm2/p114RhoGEF-Dependent Signaling. Mol Cell Biol 2015. [PMID: 26217016 DOI: 10.1128/mcb.00673-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transmembrane protein CRB3A controls epithelial cell polarization. Elucidating the molecular mechanisms of CRB3A function is essential as this protein prevents the epithelial-to-mesenchymal transition (EMT), which contributes to tumor progression. To investigate the functional impact of altered CRB3A expression in cancer cells, we expressed CRB3A in HeLa cells, which are devoid of endogenous CRB3A. While control HeLa cells display a patchy F-actin distribution, CRB3A-expressing cells form a circumferential actomyosin belt. This reorganization of the cytoskeleton is accompanied by a transition from an ameboid cell shape to an epithelial-cell-like morphology. In addition, CRB3A increases the cohesion of HeLa cells. To perform these functions, CRB3A recruits p114RhoGEF and its activator Ehm2 to the cell periphery using both functional motifs of its cytoplasmic tail and increases RhoA activation levels. ROCK1 and ROCK2 (ROCK1/2), which are critical effectors of RhoA, are also essential to modulate the cytoskeleton and cell shape downstream of CRB3A. Overall, our study highlights novel roles for CRB3A and deciphers the signaling pathway conferring to CRB3A the ability to fulfill these functions. Thereby, our data will facilitate further investigation of CRB3A functions and increase our understanding of the cellular defects associated with the loss of CRB3A expression in cancer cells.
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Blaschke M, McKinnon R, Nguyen CH, Holzner S, Zehl M, Atanasov AG, Schelch K, Krieger S, Diaz R, Frisch R, Feistel B, Jäger W, Ecker GF, Dirsch VM, Grusch M, Zupko I, Urban E, Kopp B, Krupitza G. A eudesmane-type sesquiterpene isolated from Pluchea odorata (L.) Cass. combats three hallmarks of cancer cells: Unrestricted proliferation, escape from apoptosis and early metastatic outgrowth in vitro. Mutat Res 2015; 777:79-90. [PMID: 25989051 DOI: 10.1016/j.mrfmmm.2015.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 04/05/2015] [Accepted: 04/24/2015] [Indexed: 06/04/2023]
Abstract
Pluchea odorata is ethno pharmaceutically used to treat inflammation-associated disorders. The dichloromethane extract (DME) was tested in the carrageenan-induced rat paw oedema assay investigating its effect on inflammation that was inhibited by 37%. Also an in vitro anti-neoplastic potential was reported. However, rather limited information about the bio-activity of purified compounds and their cellular mechanisms are available. Therefore, two of the most abundant eudesmanes in P. odorata were isolated and their anti-neoplastic and anti-intravasative activities were studied. HL-60 cells were treated with P. odorata compounds and metabolic activity, cell number reduction, cell cycle progression and apoptosis induction were correlated with relevant protein expression. Tumour cell intravasation through lymph endothelial monolayers was measured and potential causal mechanisms were analyzed by Western blotting. Compound PO-1 decreased the metabolic activity of HL-60 cells (IC50 = 8.9 μM after 72 h) and 10 μM PO-1 induced apoptosis, while PO-2 showed just weak anti-neoplastic activities at concentrations beyond 100 μM. PO-1 arrested the cell cycle in G1 and this correlated with induction of JunB expression. Independent of this mechanism 25 μM PO-1 decreased MCF-7 spheroid intravasation through the lymph endothelial barrier. Hence, PO-1 inhibits an early step of metastasis, impairs unrestricted proliferation and induces apoptosis at low micromolar concentrations. These results warrant further testing in vivo to challenge the potential of PO-1 as novel lead compound.
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Affiliation(s)
- Michael Blaschke
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria; Department of Clinical Pathology, Medical University of Vienna, Waehringer Guertel 18-20, Austria
| | - Ruxandra McKinnon
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Chi Huu Nguyen
- Department of Clinical Pathology, Medical University of Vienna, Waehringer Guertel 18-20, Austria; Department of Clinical Pharmacy and Diagnostics, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Silvio Holzner
- Department of Clinical Pathology, Medical University of Vienna, Waehringer Guertel 18-20, Austria
| | - Martin Zehl
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria; Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | | | - Karin Schelch
- Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Centre Vienna, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Sigurd Krieger
- Department of Clinical Pathology, Medical University of Vienna, Waehringer Guertel 18-20, Austria
| | - Rene Diaz
- Institute for Ethnobiology, Playa Diana, San José/Petén, Guatemala
| | - Richard Frisch
- Institute for Ethnobiology, Playa Diana, San José/Petén, Guatemala
| | - Björn Feistel
- Finzelberg GmbH & Co. KG, Koblenzer Strasse 48-54, D-56626 Andernach, Germany
| | - Walter Jäger
- Department of Clinical Pharmacy and Diagnostics, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Gerhard F Ecker
- Department of Pharmaceutical Chemistry, Division of Drug Design and Medicinal Chemistry, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
| | - Verena M Dirsch
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Michael Grusch
- Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Centre Vienna, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Istvan Zupko
- Department of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary
| | - Ernst Urban
- Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Brigitte Kopp
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Georg Krupitza
- Department of Clinical Pathology, Medical University of Vienna, Waehringer Guertel 18-20, Austria.
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PPP1R12A Copy Number Is Associated with Clinical Outcomes of Stage III CRC Receiving Oxaliplatin-Based Chemotherapy. Mediators Inflamm 2015; 2015:417184. [PMID: 26113782 PMCID: PMC4465766 DOI: 10.1155/2015/417184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
AIM To investigate the correlation between PPP1R12A gene copy number and clinical outcomes of oxaliplatin-based regimen in stage III colorectal cancer (CRC). METHODS A total of 139 paraffin-embedded tissue samples of stage III CRC patients who received oxaliplatin-based treatment after radical surgery were recruited. Genomic DNA was extracted and purified from paraffin-embedded sections. Quantitative PCR methods were used to detect the relative copy number (RCN) of PPP1R12A. RESULTS Statistical analysis demonstrated that low PPP1R12A RCN was associated with poor RFS (HR = 2.186, 95% CI: 1.293-3.696; P = 0.003) and OS (HR = 2.782, 95% CI: 1.531-5.052; P < 0.001). Additionally, when patients were stratified according to subgroups of stage III and tumor location, poor RFS and OS were also observed in the low PPP1R12A RCN group with significance (RFS: IIIB HR = 2.870, P < 0.001; colon HR = 1.910, P = 0.037; OS: IIIB HR = 3.527, P < 0.001; IIIC HR = 2.662, P = 0.049; rectum HR = 4.229, P = 0.002). CONCLUSION Our findings suggest the copy number of PPP1R12A can independently predict recurrence and overall survival of stage III colorectal cancer patients receiving oxaliplatin-based chemotherapy.
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Choi JW, Choi BH, Lee SH, Lee SS, Kim HC, Yu D, Chung WH, Lee KT, Chai HH, Cho YM, Lim D. Whole-Genome Resequencing Analysis of Hanwoo and Yanbian Cattle to Identify Genome-Wide SNPs and Signatures of Selection. Mol Cells 2015; 38:466-73. [PMID: 26018558 PMCID: PMC4443289 DOI: 10.14348/molcells.2015.0019] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/20/2015] [Accepted: 03/13/2015] [Indexed: 01/11/2023] Open
Abstract
Over the last 30 years, Hanwoo has been selectively bred to improve economically important traits. Hanwoo is currently the representative Korean native beef cattle breed, and it is believed that it shared an ancestor with a Chinese breed, Yanbian cattle, until the last century. However, these two breeds have experienced different selection pressures during recent decades. Here, we whole-genome sequenced 10 animals each of Hanwoo and Yanbian cattle (20 total) using the Illumina HiSeq 2000 sequencer. A total of approximately 3.12 and 3.07 billion sequence reads were mapped to the bovine reference sequence assembly (UMD 3.1) at an average of approximately 10.71- and 10.53-fold coverage for Hanwoo and Yanbian cattle, respectively. A total of 17,936,399 single nucleotide polymorphisms (SNPs) were yielded, of which 22.3% were found to be novel. By annotating the SNPs, we further retrieved numerous nonsynonymous SNPs that may be associated with traits of interest in cattle. Furthermore, we performed whole-genome screening to detect signatures of selection throughout the genome. We located several promising selective sweeps that are potentially responsible for economically important traits in cattle; the PPP1R12A gene is an example of a gene that potentially affects intramuscular fat content. These discoveries provide valuable genomic information regarding potential genomic markers that could predict traits of interest for breeding programs of these cattle breeds.
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Affiliation(s)
- Jung-Woo Choi
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Bong-Hwan Choi
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Seung-Hwan Lee
- Division of Animal and Dairy Science, Chung Nam National University, Daejeon 305-764,
Korea
| | - Seung-Soo Lee
- Animal Genetic and Breeding Division, National Institute of Animal Science, Cheon-An 331-808,
Korea
| | - Hyeong-Cheol Kim
- Hanwoo Experiment Station, National Institute of Animal Science, RDA, Pyeongchang 232-950,
Korea
| | - Dayeong Yu
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Won-Hyong Chung
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Kyung-Tai Lee
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Han-Ha Chai
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Yong-Min Cho
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
| | - Dajeong Lim
- Animal Genomics and Bioinformatics Division, National Institute of Animal Science, Rural Development Administration, Suwon 441-706,
Korea
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Abstract
Cellular responses to environmental cues involve the mobilization of GTPases, protein kinases and phosphoprotein phosphatases. The spatial organization of these signalling enzymes by scaffold proteins helps to guide the flow of molecular information. Allosteric modulation of scaffolded enzymes can alter their catalytic activity or sensitivity to second messengers in a manner that augments, insulates or terminates local cellular events. This Review examines the features of scaffold proteins and highlights examples of locally organized groups of signalling enzymes that drive essential physiological processes, including hormone action, heart rate, cell division, organelle movement and synaptic transmission.
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76
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Chang AN, Battiprolu PK, Cowley PM, Chen G, Gerard RD, Pinto JR, Hill JA, Baker AJ, Kamm KE, Stull JT. Constitutive phosphorylation of cardiac myosin regulatory light chain in vivo. J Biol Chem 2015; 290:10703-16. [PMID: 25733667 DOI: 10.1074/jbc.m115.642165] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 01/03/2023] Open
Abstract
In beating hearts, phosphorylation of myosin regulatory light chain (RLC) at a single site to 0.45 mol of phosphate/mol by cardiac myosin light chain kinase (cMLCK) increases Ca(2+) sensitivity of myofilament contraction necessary for normal cardiac performance. Reduction of RLC phosphorylation in conditional cMLCK knock-out mice caused cardiac dilation and loss of cardiac performance by 1 week, as shown by increased left ventricular internal diameter at end-diastole and decreased fractional shortening. Decreased RLC phosphorylation by conventional or conditional cMLCK gene ablation did not affect troponin-I or myosin-binding protein-C phosphorylation in vivo. The extent of RLC phosphorylation was not changed by prolonged infusion of dobutamine or treatment with a β-adrenergic antagonist, suggesting that RLC is constitutively phosphorylated to maintain cardiac performance. Biochemical studies with myofilaments showed that RLC phosphorylation up to 90% was a random process. RLC is slowly dephosphorylated in both noncontracting hearts and isolated cardiac myocytes from adult mice. Electrically paced ventricular trabeculae restored RLC phosphorylation, which was increased to 0.91 mol of phosphate/mol of RLC with inhibition of myosin light chain phosphatase (MLCP). The two RLCs in each myosin appear to be readily available for phosphorylation by a soluble cMLCK, but MLCP activity limits the amount of constitutive RLC phosphorylation. MLCP with its regulatory subunit MYPT2 bound tightly to myofilaments was constitutively phosphorylated in beating hearts at a site that inhibits MLCP activity. Thus, the constitutive RLC phosphorylation is limited physiologically by low cMLCK activity in balance with low MLCP activity.
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Affiliation(s)
| | | | - Patrick M Cowley
- the Veterans Affairs Medical Center, San Francisco, California 94143, the University of California, San Francisco, California 94143, and
| | | | - Robert D Gerard
- Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Jose R Pinto
- the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306
| | - Joseph A Hill
- Internal Medicine (Cardiology), and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Anthony J Baker
- the Veterans Affairs Medical Center, San Francisco, California 94143, the University of California, San Francisco, California 94143, and
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77
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Beach JR, Hammer JA. Myosin II isoform co-assembly and differential regulation in mammalian systems. Exp Cell Res 2015; 334:2-9. [PMID: 25655283 DOI: 10.1016/j.yexcr.2015.01.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 10/24/2022]
Abstract
Non-muscle myosin 2 (NM2) is a major force-producing, actin-based motor in mammalian non-muscle cells, where it plays important roles in a broad range of fundamental biological processes, including cytokinesis, cell migration, and epithelial barrier function. This breadth of function at the tissue and cellular levels suggests extensive diversity and differential regulation of NM2 bipolar filaments, the major, if not sole, functional form of NM2s in vivo. Previous in vitro, cellular and animal studies indicate that some of this diversity is supported by the existence of multiple NM2 isoforms. Moreover, two recent studies have shown that these isoforms can co-assemble to form heterotypic filaments, further expanding functional diversity. In addition to isoform co-assembly, cells may differentially regulate NM2 function via isoform-specific expression, RLC phosphorylation, MHC phosphorylation or regulation via binding partners. Here, we provide a brief summary of NM2 filament assembly, summarize the recent findings regarding NM2 isoform co-assembly, consider the mechanisms cells might utilize to differentially regulate NM2 isoforms, and review the data available to support these mechanisms.
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Affiliation(s)
- Jordan R Beach
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - John A Hammer
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Madsen CD, Hooper S, Tozluoglu M, Bruckbauer A, Fletcher G, Erler JT, Bates PA, Thompson B, Sahai E. STRIPAK components determine mode of cancer cell migration and metastasis. Nat Cell Biol 2015; 17:68-80. [PMID: 25531779 PMCID: PMC5354264 DOI: 10.1038/ncb3083] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 11/11/2014] [Indexed: 12/15/2022]
Abstract
The contractile actomyosin cytoskeleton and its connection to the plasma membrane are critical for control of cell shape and migration. We identify three STRIPAK complex components, FAM40A, FAM40B and STRN3, as regulators of the actomyosin cortex. We show that FAM40A negatively regulates the MST3 and MST4 kinases, which promote the co-localization of the contractile actomyosin machinery with the Ezrin/Radixin/Moesin family proteins by phosphorylating the inhibitors of PPP1CB, PPP1R14A-D. Using computational modelling, in vitro cell migration assays and in vivo breast cancer metastasis assays we demonstrate that co-localization of contractile activity and actin-plasma membrane linkage reduces cell speed on planar surfaces, but favours migration in confined environments similar to those observed in vivo. We further show that FAM40B mutations found in human tumours uncouple it from PP2A and enable it to drive a contractile phenotype, which may underlie its role in human cancer.
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Affiliation(s)
- Chris D. Madsen
- Tumour Cell Biology Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
| | - Steven Hooper
- Tumour Cell Biology Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Melda Tozluoglu
- Biomolecular Modelling Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Andreas Bruckbauer
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Georgina Fletcher
- Epithelial Biology Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Janine T. Erler
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
| | - Paul A. Bates
- Biomolecular Modelling Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Barry Thompson
- Epithelial Biology Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
| | - Erik Sahai
- Tumour Cell Biology Laboratory, Cancer Research UK London Research Institute, 44 Lincoln’s Inn Fields, London, WC2A 3LY, UK
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79
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Ihara E, Yu Q, Chappellaz M, MacDonald JA. ERK and p38MAPK pathways regulate myosin light chain phosphatase and contribute to Ca2+ sensitization of intestinal smooth muscle contraction. Neurogastroenterol Motil 2015; 27:135-46. [PMID: 25557225 DOI: 10.1111/nmo.12491] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/20/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND Mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase (ERK) and p38MAPK, are known regulators of smooth muscle contractility. The contraction of smooth muscle is mainly regulated by the phosphorylation of regulatory light chains of myosin II (LC20), which is driven by the balance between myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We hypothesized that one possible mechanism for MAPK-dependent modulation of intestinal smooth muscle contractility is via the regulation of MLCP activity. METHODS Contractile responses to carbachol (CCh) and effects of MAPK inhibitors on CCh-induced contractions were assessed with isolated rat ileal longitudinal smooth muscle strips. Biochemical assessments of MLCP activity and myosin phosphatse targeting subunit (MYPT1) and CPI-17 phosphorylations were completed. KEY RESULTS Treatment of ileal smooth muscle with PD98059 (10 μM; MEK inhibitor) or SB203580 (10 μM; p38MAPK inhibitor) significantly inhibited CCh-induced contractile force. Decreased MLCP activity was observed during sustained contractions induced by CCh; the MLCP activity was recovered by treatment with PD98059 and SB203580. However, MYPT1 (Thr697 and Thr855) and CPI-17 (Thr38) phosphorylations were not affected. Application of ML-7 (MLCK inhibitor) during CCh-induced sustained contraction elicited an MLCP-dependent relaxation, the rate of which was accelerated by application of PD98059 and SB203580 with proportional changes in LC20 phosphorylation levels but not MYPT1 phosphorylation (Thr697 or Thr855). CONCLUSIONS & INFERENCES ERK and p38MAPK contribute to CCh-induced sustained contraction in a LC20 phosphorylation dependent manner. Moreover, both kinases inhibit MLCP activity possibly by a novel mechanism.
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Affiliation(s)
- E Ihara
- Smooth Muscle Research Group at the Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB, Canada; Department of Medicine and Bioregulatory Science, Kyushu University, Higashi-ku, Fukuoka, Japan
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Chen CP, Chen X, Qiao YN, Wang P, He WQ, Zhang CH, Zhao W, Gao YQ, Chen C, Tao T, Sun J, Wang Y, Gao N, Kamm KE, Stull JT, Zhu MS. In vivo roles for myosin phosphatase targeting subunit-1 phosphorylation sites T694 and T852 in bladder smooth muscle contraction. J Physiol 2014; 593:681-700. [PMID: 25433069 DOI: 10.1113/jphysiol.2014.283853] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/18/2014] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Force production and maintenance in smooth muscle is largely controlled by myosin regulatory light chain (RLC) phosphorylation, which relies on a balance between Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) activities. MYPT1 is the regulatory subunit of MLCP that biochemically inhibits MLCP activity via T694 or T852 phosphorylation in vitro. Here we separately investigated the contribution of these two phosphorylation sites in bladder smooth muscles by establishing two single point mutation mouse lines, T694A and T852A, and found that phosphorylation of MYPT1 T694, but not T852, mediates force maintenance via inhibition of MLCP activity and enhancement of RLC phosphorylation in vivo. Our findings reveal the role of MYPT1 T694/T852 phosphorylation in vivo in regulation of smooth muscle contraction. ABSTRACT Force production and maintenance in smooth muscle is largely controlled by different signalling modules that fine tune myosin regulatory light chain (RLC) phosphorylation, which relies on a balance between Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) activities. To investigate the regulation of MLCP activity in vivo, we analysed the role of two phosphorylation sites on MYPT1 (regulatory subunit of MLCP) that biochemically inhibit MLCP activity in vitro. MYPT1 is constitutively phosphorylated at T694 by unidentified kinases in vivo, whereas the T852 site is phosphorylated by RhoA-associated protein kinase (ROCK). We established two mouse lines with alanine substitution of T694 or T852. Isolated bladder smooth muscle from T852A mice displayed no significant changes in RLC phosphorylation or force responses, but force was inhibited with a ROCK inhibitor. In contrast, smooth muscles containing the T694A mutation showed a significant reduction of force along with reduced RLC phosphorylation. The contractile responses of T694A mutant smooth muscle were also independent of ROCK activation. Thus, phosphorylation of MYPT1 T694, but not T852, is a primary mechanism contributing to inhibition of MLCP activity and enhancement of RLC phosphorylation in vivo. The constitutive phosphorylation of MYPT1 T694 may provide a mechanism for regulating force maintenance of smooth muscle.
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Affiliation(s)
- Cai-Ping Chen
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing, China
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81
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Oridonin suppress cell migration via regulation of nonmuscle myosin IIA. Cytotechnology 2014; 68:389-97. [PMID: 25297007 DOI: 10.1007/s10616-014-9790-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/19/2014] [Indexed: 12/15/2022] Open
Abstract
Oridonin, which is isolated from Chinese herb Rabdosia rubescens (Hemsl.) Hara, has been implicated in regulation of tumor cell migration and invasion. In this study, treatment with oridonin enhanced the phosphorylation of myosin regulatory light chain (T18/S19) that regulates the ATPase activity of myosin IIA. Meanwhile, stress fibers were significantly more prominent after oridonin incubation, which impaired cell migration in transwell migration assays. All of these effects may be caused by the decreased interaction between myosin IIA and myosin phosphatase complex, but not kinases. Our data provide clear evidence of this novel pharmacological function for oridonin in treating cancer cell migration.
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82
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Mahavadi S, Nalli A, Al-Shboul O, Murthy KS. Inhibition of MLC20 phosphorylation downstream of Ca2+ and RhoA: A novel mechanism involving phosphorylation of myosin phosphatase interacting protein (M-RIP) by PKG and stimulation of MLC phosphatase activity. Cell Biochem Biophys 2014; 68:1-8. [PMID: 23723008 DOI: 10.1007/s12013-013-9677-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous studies have shown that cGMP-dependent protein kinase (PKG) act on several targets in the contractile pathway to reduce intracellular Ca(2+) and/or augment RhoA-regulated myosin light chain phosphatase (MLCP) activity and cause muscle relaxation. Recent studies have identified a novel protein M-RIP that associates with MYPT1, the regulatory subunit of MLCP. Herein, we examine whether PKG enhance MLCP activity downstream of Ca(2+) and RhoA via phosphorylation of M-RIP in gastric smooth muscle cells. Treatment of permeabilized muscle cells with 10 μM Ca(2+) caused an increase in MLC20 phosphorylation and muscle contraction, but had no effect on Rho kinase activity. Activators of PKG (GSNO or cGMP) decreased MLC20 phosphorylation and contraction in response to 10 μM Ca(2+), implying existence of inhibitory mechanism independent of Ca(2+) and RhoA. The effect of PKG on Ca(2+)-induced MLC20 phosphorylation was attenuated by M-RIP siRNA. Both GSNO and 8-pCPT-cGMP induced phosphorylation of M-RIP; phosphorylation was accompanied by an increase in the association of M-RIP with MYPT1 and MLCP activity. Taken together, these results provide evidence that PKG induces phosphorylation of M-RIP and enhances its association with MYPT1 to augment MLCP activity and MLC20 dephosphorylation and inhibits muscle contraction, downstream of Ca(2+)- or RhoA-dependent pathways.
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Affiliation(s)
- Sunila Mahavadi
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, 23298-0711, USA
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83
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Abstract
AIM: To investigate the expression of myosin light chain kinase (MLCK) in pancreatic tissue of severe acute pancreatitis (SAP) rats.
METHODS: Fifty-six male SD rats were randomly and equally assigned into a normal control group (C) and a SAP group (S). SAP was reproduced in rats of group S by retrograde injection of 4% sodium taurocholate into the biliopancreatic duct, while group C underwent a sham operation. The rats were killed at 6, 12, 24 and 48 h after SAP induction. Serum amylase (AMY) was measured dynamically. The gross and pathological changes in the pancreas were observed under a light microscope. The ultrastructure and tight junction (TJ) changes in the pancreas were observed with an electron microscope. The localization and expression of MLCK in pancreatic tissue were investigated by immunohistochemical method. The concentration of serum tumor necrosis factor α (TNF-α) was determined by ELISA.
RESULTS: Compared to group C, the AMY concentration and pancreatic pathology score were significantly higher (P < 0.05); pancreatic ultrastructure damage was more obvious and TJ widened significantly; MLCK was positively expressed in the cytoplasm of cells in the pancreas, and the mean density was elevated more significantly (P < 0.05); and serum TNF-α concentration significantly increased in group S (P < 0.05). The mean density of MLCK in the pancreas was positively correlated with pathological score and serum TNF-α concentration (r = 0.804, 0.796, P < 0.05 for both).
CONCLUSION: Up-regulated expression of MLCK protein in the pancreas and elevated serum TNF-α concentration may regulate the integrity of intercellular tight junctions, which may be associated with the severity of SAP and play a role in the pathogenesis of acute pancreatitis.
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1α,25-dihydroxyvitamin D3 ameliorates seawater aspiration-induced acute lung injury via NF-κB and RhoA/Rho kinase pathways. PLoS One 2014; 9:e104507. [PMID: 25118599 PMCID: PMC4132109 DOI: 10.1371/journal.pone.0104507] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 07/10/2014] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION Inflammation and pulmonary edema are involved in the pathogenesis of seawater aspiration-induced acute lung injury (ALI). Although several studies have reported that 1α,25-Dihydroxyvitamin D3 (calcitriol) suppresses inflammation, it has not been confirmed to be effective in seawater aspiration-induced ALI. Thus, we investigated the effect of calcitriol on seawater aspiration-induced ALI and explored the probable mechanism. METHODS Male SD rats receiving different doses of calcitriol or not, underwent seawater instillation. Then lung samples were collected at 4 h for analysis. In addition, A549 cells and rat pulmonary microvascular endothelial cells (RPMVECs) were cultured with calcitriol or not and then stimulated with 25% seawater for 40 min. After these treatments, cells samples were collected for analysis. RESULTS Results from real-time PCR showed that seawater stimulation up-regulated the expression of vitamin D receptor in lung tissues, A549 cells and RPMVECs. Seawater stimulation also activates NF-κB and RhoA/Rho kinase pathways. However, we found that pretreatment with calcitriol significantly inhibited the activation of NF-κB and RhoA/Rho kinase pathways. Meanwhile, treatment of calcitriol also improved lung histopathologic changes, reduced inflammation, lung edema and vascular leakage. CONCLUSIONS These results demonstrated that NF-κB and RhoA/Rho kinase pathways are critical in the development of lung inflammation and pulmonary edema and that treatment with calcitriol could ameliorate seawater aspiration-induced ALI, which was probably through the inhibition of NF-κB and RhoA/Rho kinase pathways.
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Dippold RP, Fisher SA. A bioinformatic and computational study of myosin phosphatase subunit diversity. Am J Physiol Regul Integr Comp Physiol 2014; 307:R256-70. [PMID: 24898838 PMCID: PMC4121627 DOI: 10.1152/ajpregu.00145.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 05/25/2014] [Indexed: 01/01/2023]
Abstract
Variability in myosin phosphatase (MP) subunits may provide specificity in signaling pathways that regulate muscle tone. We utilized public databases and computational algorithms to investigate the phylogenetic diversity of MP regulatory (PPP1R12A-C) and inhibitory (PPP1R14A-D) subunits. The comparison of exonic coding sequences and expression data confirmed or refuted the existence of isoforms and their tissue-specific expression in different model organisms. The comparison of intronic and exonic sequences identified potential expressional regulatory elements. As examples, smooth muscle MP regulatory subunit (PPP1R12A) is highly conserved through evolution. Its alternative exon E24 is present in fish through mammals with two invariant features: 1) a reading frame shift generating a premature termination codon and 2) a hexanucleotide sequence adjacent to the 3' splice site hypothesized to be a novel suppressor of exon splicing. A characteristic of the striated muscle MP regulatory subunit (PPP1R12B) locus is numerous and phylogenetically variable transcriptional start sites. In fish this locus only codes for the small (M21) subunit, suggesting the primordial function of this gene. Inhibitory subunits show little intragenic variability; their diversity is thought to have arisen by expansion and tissue-specific expression of different gene family members. We demonstrate differences in the regulatory landscape between smooth muscle enriched (PPP1R14A) and more ubiquitously expressed (PPP1R14B) family members and identify deeply conserved intronic sequence and predicted transcriptional cis-regulatory elements. This bioinformatic and computational study has uncovered a number of attributes of MP subunits that supports selection of ideal model organisms and testing of hypotheses regarding their physiological significance and regulated expression.
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Affiliation(s)
- Rachael P Dippold
- Department of Medicine, Cardiology, University of Maryland Baltimore, Baltimore, Maryland
| | - Steven A Fisher
- Department of Medicine, Cardiology, University of Maryland Baltimore, Baltimore, Maryland
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Betapudi V. Life without double-headed non-muscle myosin II motor proteins. Front Chem 2014; 2:45. [PMID: 25072053 PMCID: PMC4083560 DOI: 10.3389/fchem.2014.00045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 06/19/2014] [Indexed: 11/20/2022] Open
Abstract
Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC) belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients' life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.
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Affiliation(s)
- Venkaiah Betapudi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Department of Physiology and Biophysics, Case Western Reserve University Cleveland, OH, USA
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87
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Zhang X, Ma D, Caruso M, Lewis M, Qi Y, Yi Z. Quantitative phosphoproteomics reveals novel phosphorylation events in insulin signaling regulated by protein phosphatase 1 regulatory subunit 12A. J Proteomics 2014; 109:63-75. [PMID: 24972320 DOI: 10.1016/j.jprot.2014.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/11/2014] [Accepted: 06/14/2014] [Indexed: 01/07/2023]
Abstract
UNLABELLED Serine/threonine protein phosphatase 1 regulatory subunit 12A (PPP1R12A) modulates the activity and specificity of the catalytic subunit of protein phosphatase 1, regulating various cellular processes via dephosphorylation. Nonetheless, little is known about phosphorylation events controlled by PPP1R12A in skeletal muscle insulin signaling. Here, we used quantitative phosphoproteomics to generate a global picture of phosphorylation events regulated by PPP1R12A in a L6 skeletal muscle cell line, which were engineered for inducible PPP1R12A knockdown. Phosphoproteomics revealed 3876 phosphorylation sites (620 were novel) in these cells. Furthermore, PPP1R12A knockdown resulted in increased overall phosphorylation in L6 cells at the basal condition, and changed phosphorylation levels for 698 sites (assigned to 295 phosphoproteins) at the basal and/or insulin-stimulated conditions. Pathway analysis on the 295 phosphoproteins revealed multiple significantly enriched pathways related to insulin signaling, such as mTOR signaling and RhoA signaling. Moreover, phosphorylation levels for numerous regulatory sites in these pathways were significantly changed due to PPP1R12A knockdown. These results indicate that PPP1R12A indeed plays a role in skeletal muscle insulin signaling, providing novel insights into the biology of insulin action. This new information may facilitate the design of experiments to better understand mechanisms underlying skeletal muscle insulin resistance and type 2 diabetes. BIOLOGICAL SIGNIFICANCE These results identify a large number of potential new substrates of serine/threonine protein phosphatase 1 and suggest that serine/threonine protein phosphatase 1 regulatory subunit 12A indeed plays a regulatory role in multiple pathways related to insulin action, providing novel insights into the biology of skeletal muscle insulin signaling. This information may facilitate the design of experiments to better understand the molecular mechanism responsible for skeletal muscle insulin resistance and associated diseases, such as type 2 diabetes and cardiovascular diseases.
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Affiliation(s)
- Xiangmin Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Danjun Ma
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Michael Caruso
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Monique Lewis
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Yue Qi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA.
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88
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Qiao YN, He WQ, Chen CP, Zhang CH, Zhao W, Wang P, Zhang L, Wu YZ, Yang X, Peng YJ, Gao JM, Kamm KE, Stull JT, Zhu MS. Myosin phosphatase target subunit 1 (MYPT1) regulates the contraction and relaxation of vascular smooth muscle and maintains blood pressure. J Biol Chem 2014; 289:22512-23. [PMID: 24951589 DOI: 10.1074/jbc.m113.525444] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Myosin light chain phosphatase with its regulatory subunit, myosin phosphatase target subunit 1 (MYPT1) modulates Ca(2+)-dependent phosphorylation of myosin light chain by myosin light chain kinase, which is essential for smooth muscle contraction. The role of MYPT1 in vascular smooth muscle was investigated in adult MYPT1 smooth muscle specific knock-out mice. MYPT1 deletion enhanced phosphorylation of myosin regulatory light chain and contractile force in isolated mesenteric arteries treated with KCl and various vascular agonists. The contractile responses of arteries from knock-out mice to norepinephrine were inhibited by Rho-associated kinase (ROCK) and protein kinase C inhibitors and were associated with inhibition of phosphorylation of the myosin light chain phosphatase inhibitor CPI-17. Additionally, stimulation of the NO/cGMP/protein kinase G (PKG) signaling pathway still resulted in relaxation of MYPT1-deficient mesenteric arteries, indicating phosphorylation of MYPT1 by PKG is not a major contributor to the relaxation response. Thus, MYPT1 enhances myosin light chain phosphatase activity sufficient for blood pressure maintenance. Rho-associated kinase phosphorylation of CPI-17 plays a significant role in enhancing vascular contractile responses, whereas phosphorylation of MYPT1 in the NO/cGMP/PKG signaling module is not necessary for relaxation.
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Affiliation(s)
- Yan-Ning Qiao
- From the Key Laboratory of MOE for Modern Teaching Technology, Shaanxi Normal University, Xi'an 710062, China, Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Wei-Qi He
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Cai-Ping Chen
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Cheng-Hai Zhang
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Wei Zhao
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Pei Wang
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Lin Zhang
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, Wenzhou 325035, China
| | - Yan-Ze Wu
- From the Key Laboratory of MOE for Modern Teaching Technology, Shaanxi Normal University, Xi'an 710062, China
| | - Xiao Yang
- State Key Laboratory of Proteomics, Genetic Laboratory of Development and Disease, Institute of Biotechnology, Beijing 100071, China, and
| | - Ya-Jing Peng
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China
| | - Ji-Min Gao
- Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, Wenzhou 325035, China
| | - Kristine E Kamm
- the Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9040
| | - James T Stull
- the Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9040
| | - Min-Sheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Animal Models of Disease, Nanjing University, Nanjing 210061, China, Zhejiang Provincial Key Laboratory for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, Wenzhou 325035, China,
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89
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Tsai MH, Chang AN, Huang J, He W, Sweeney HL, Zhu M, Kamm KE, Stull JT. Constitutive phosphorylation of myosin phosphatase targeting subunit-1 in smooth muscle. J Physiol 2014; 592:3031-51. [PMID: 24835173 DOI: 10.1113/jphysiol.2014.273011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Smooth muscle contraction initiated by myosin regulatory light chain (RLC) phosphorylation is dependent on the relative activities of Ca(2+)-calmodulin-dependent myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We have investigated the physiological role of the MLCP regulatory subunit MYPT1 in bladder smooth muscle containing a smooth muscle-specific deletion of MYPT1 in adult mice. Deep-sequencing analyses of mRNA and immunoblotting revealed that MYPT1 depletion reduced the amount of PP1cδ with no compensatory changes in expression of other MYPT1 family members. Phosphatase activity towards phosphorylated smooth muscle heavy meromyosin was proportional to the amount of PP1cδ in total homogenates from wild-type or MYPT1-deficient tissues. Isolated MYPT1-deficient tissues from MYPT1(SM-/-) mice contracted with moderate differences in response to KCl and carbachol treatments, and relaxed rapidly with comparable rates after carbachol removal and only 1.5-fold slower after KCl removal. Measurements of phosphorylated proteins in the RLC signalling and actin polymerization modules during contractions revealed moderate changes. Using a novel procedure to quantify total phosphorylation of MYPT1 at Thr696 and Thr853, we found substantial phosphorylation in wild-type tissues under resting conditions, predicting attenuation of MLCP activity. Reduced PP1cδ activity in MYPT1-deficient tissues may be similar to the attenuated MLCP activity in wild-type tissues resulting from constitutively phosphorylated MYPT1. Constitutive phosphorylation of MYPT1 Thr696 and Thr853 may thus represent a physiological mechanism acting in concert with agonist-induced MYPT1 phosphorylation to inhibit MLCP activity. In summary, MYPT1 deficiency may not cause significant derangement of smooth muscle contractility because the effective MLCP activity is not changed.
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Affiliation(s)
- Ming-Ho Tsai
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Audrey N Chang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jian Huang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Weiqi He
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - H Lee Sweeney
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Minsheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
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90
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Khasnis M, Nakatomi A, Gumpper K, Eto M. Reconstituted human myosin light chain phosphatase reveals distinct roles of two inhibitory phosphorylation sites of the regulatory subunit, MYPT1. Biochemistry 2014; 53:2701-9. [PMID: 24712327 PMCID: PMC4010256 DOI: 10.1021/bi5001728] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
The myosin light chain phosphatase
(MLCP) is a cytoskeleton-associated
protein phosphatase-1 (PP1) holoenzyme and a RhoA/ROCK effector, regulating
cytoskeletal reorganization. ROCK-induced phosphorylation of the MLCP
regulatory subunit (MYPT1) at two sites, Thr696 and Thr853, suppresses
the activity, although little is known about the difference in the
role. Here, we developed a new method for the preparation of the recombinant
human MLCP complex and determined the molecular and cellular basis
of inhibitory phosphorylation. The recombinant MLCP partially purified
from mammalian cell lysates retained characteristics of the native
enzyme, such that it was fully active without Mn2+ and
sensitive to PP1 inhibitor compounds. Selective thio-phosphorylation
of MYPT1 at Thr696 with ROCK inhibited the MLCP activity 30%, whereas
the Thr853 thio-phosphorylation did not alter the phosphatase activity.
Interference with the docking of phospho-Thr696 at the active site
weakened the inhibition, suggesting selective autoinhibition induced
by phospho-Thr696. Both Thr696 and Thr853 sites underwent autodephosphorylation.
Compared with that of Thr853, phosphorylation of Thr696 was more stable,
and it facilitated Thr853 phosphorylation. Endogenous MYPT1 at Thr696
was spontaneously phosphorylated in quiescent human leiomyosarcoma
cells. Serum stimulation of the cells resulted in dissociation of
MYPT1 from myosin and PP1C in parallel with an increase in the level
of Thr853 phosphorylation. The C-terminal domain of human MYPT1(495–1030)
was responsible for the binding to the N-terminal portion of myosin
light meromyosin. The spontaneous phosphorylation at Thr696 may adjust
the basal activity of cellular MLCP and affect the temporal phosphorylation
at Thr853 that is synchronized with myosin targeting.
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Affiliation(s)
- Mukta Khasnis
- Department of Molecular Physiology and Biophysics, Thomas Jefferson University Jefferson Medical School , and Kimmel Cancer Center , 1020 Locust Street, Philadelphia, Pennsylvania 19107, United States
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91
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Joo EE, Yamada KM. MYPT1 regulates contractility and microtubule acetylation to modulate integrin adhesions and matrix assembly. Nat Commun 2014; 5:3510. [PMID: 24667306 DOI: 10.1038/ncomms4510] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/25/2014] [Indexed: 01/16/2023] Open
Abstract
Although much is known about how individual cytoskeletal systems contribute to physiological processes such as cell migration and branching morphogenesis, little is known about how these different systems actively coordinate their functions after polymerization. Here we show that both fibroblasts and developing glands reciprocally coordinate levels of cellular contractility and microtubule acetylation. We find that this balance is achieved by interaction of the myosin phosphatase target subunit of myosin phosphatase with either myosin light chain or HDAC6, a microtubule deacetylase. This balance of contractility and microtubule acetylation controls progression of adhesion maturation by regulating surface density of α5β1 integrin and fibronectin. Thus, we propose that a homeostatic balance between contractility and microtubule acetylation is mediated by myosin phosphatase via controlled activation and deactivation of myosin II and HDAC6. This regulates the surface density of α5β1 integrin to modulate fibronectin matrix assembly and governs rates of cell migration and branching morphogenesis.
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Affiliation(s)
- E Emily Joo
- Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kenneth M Yamada
- Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
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92
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Inhibition of tumour spheroid-induced prometastatic intravasation gates in the lymph endothelial cell barrier by carbamazepine: drug testing in a 3D model. Arch Toxicol 2013; 88:691-9. [PMID: 24352538 DOI: 10.1007/s00204-013-1183-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 12/09/2013] [Indexed: 01/26/2023]
Abstract
Metastatic breast cancer is linked to an undesired prognosis. One early and crucial metastatic step is the interaction of cancer emboli with adjacent stroma or endothelial cells, and understanding the mechanisms of this interaction provides the basis to define new targets as well as drugs for therapy and disease management. A three-dimensional (3D) co-culture model allowing the examination of lymphogenic dissemination of breast cancer cells was recently developed which facilitates not only the study of metastatic processes but also the testing of therapeutic concepts. This 3D setting consists of MCF-7 breast cancer cell spheroids (representing a ductal and hormone-dependent subtype) and of hTERT-immortalised lymph endothelial cell (LEC; derived from foreskin) monolayers. Tumour spheroids repel the continuous LEC layer, thereby generating "circular chemorepellent-induced defects" (CCIDs) that are reminiscent to the entry gates through which tumour emboli intravasate lymphatics. We found that the ion channel blocker carbamazepine (which is clinically used to treat epilepsy, schizophrenia and other neurological disorders) inhibited CCID formation significantly. This effect correlated with the inhibition of the activities of NF-κB, which contributes to cell motility, and with the inactivation of the mobility proteins MLC2, MYPT1 and FAK which are necessary for LEC migration. NF-κB activity and cell movement are prerequisites of CCID formation. On the other hand, the expression of the motility protein paxillin and of the NF-κB-dependent adhesion mediator ICAM-1 was unchanged. Also the activity of ALOX12 was unaffected. ALOX12 is the main enzyme synthesising 12(S)-HETE, which then triggers CCID formation. The relevance of the inhibition of CYP1A1, which is also involved in the generation of mid-chain HETEs such as 12(S)-HETE, by carbamazepine remains to be established, because the constitutive level of 12(S)-HETE did not change upon carbamazepine treatment. Nevertheless, the effect of carbamazepine on the inhibition of CCID formation as an early step of breast cancer metastasis was significant and substantial (~30 %) and achieved at concentrations that are found in the plasma of carbamazepine-treated adults (40-60 μM). The fact that carbamazepine is a drug approved by the US Food and Drug Administration facilitates a "from-bench-to-bedside" perspective. Therefore, the here presented data should undergo scrutiny in vivo.
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93
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Simard E, Kovacs JJ, Miller WE, Kim J, Grandbois M, Lefkowitz RJ. β-Arrestin regulation of myosin light chain phosphorylation promotes AT1aR-mediated cell contraction and migration. PLoS One 2013; 8:e80532. [PMID: 24255721 PMCID: PMC3821855 DOI: 10.1371/journal.pone.0080532] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 10/14/2013] [Indexed: 12/20/2022] Open
Abstract
Over the last decade, it has been established that G-protein-coupled receptors (GPCRs) signal not only through canonical G-protein-mediated mechanisms, but also through the ubiquitous cellular scaffolds β-arrestin-1 and β-arrestin-2. Previous studies have implicated β-arrestins as regulators of actin reorganization in response to GPCR stimulation while also being required for membrane protrusion events that accompany cellular motility. One of the most critical events in the active movement of cells is the cyclic phosphorylation and activation of myosin light chain (MLC), which is required for cellular contraction and movement. We have identified the myosin light chain phosphatase Targeting Subunit (MYPT-1) as a binding partner of the β-arrestins and found that β-arrestins play a role in regulating the turnover of phosphorylated myosin light chain. In response to stimulation of the angiotensin Type 1a Receptor (AT1aR), MLC phosphorylation is induced quickly and potently. We have found that β-arrestin-2 facilitates dephosphorylation of MLC, while, in a reciprocal fashion, β-arrestin 1 limits dephosphorylation of MLC. Intriguingly, loss of either β-arrestin-1 or 2 blocks phospho-MLC turnover and causes a decrease in the contraction of cells as monitored by atomic force microscopy (AFM). Furthermore, by employing the β-arrestin biased ligand [Sar1,Ile4,Ile8]-Ang, we demonstrate that AT1aR-mediated cellular motility involves a β-arrestin dependent component. This suggests that the reciprocal regulation of MLC phosphorylation status by β-arrestins-1 and 2 causes turnover in the phosphorylation status of MLC that is required for cell contractility and subsequent chemotaxic motility.
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Affiliation(s)
- Elie Simard
- Département de Pharmacologie, Faculté de Médecine et des Sciences de la Santé de l’Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Jeffrey J. Kovacs
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - William E. Miller
- Department of Molecular Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Jihee Kim
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Michel Grandbois
- Département de Pharmacologie, Faculté de Médecine et des Sciences de la Santé de l’Université de Sherbrooke, Sherbrooke, Québec, Canada
- Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé de l’Université de Sherbrooke, Sherbrooke, Québec, Canada
- Chaire de Recherche Canadienne en Nanopharmacologie et Microscopie à Force Atomique, Faculté de Médecine et des Sciences de la Santé de l’Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Robert J. Lefkowitz
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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94
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Laughlin MH, Davis MJ, Secher NH, van Lieshout JJ, Arce-Esquivel AA, Simmons GH, Bender SB, Padilla J, Bache RJ, Merkus D, Duncker DJ. Peripheral circulation. Compr Physiol 2013; 2:321-447. [PMID: 23728977 DOI: 10.1002/cphy.c100048] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Blood flow (BF) increases with increasing exercise intensity in skeletal, respiratory, and cardiac muscle. In humans during maximal exercise intensities, 85% to 90% of total cardiac output is distributed to skeletal and cardiac muscle. During exercise BF increases modestly and heterogeneously to brain and decreases in gastrointestinal, reproductive, and renal tissues and shows little to no change in skin. If the duration of exercise is sufficient to increase body/core temperature, skin BF is also increased in humans. Because blood pressure changes little during exercise, changes in distribution of BF with incremental exercise result from changes in vascular conductance. These changes in distribution of BF throughout the body contribute to decreases in mixed venous oxygen content, serve to supply adequate oxygen to the active skeletal muscles, and support metabolism of other tissues while maintaining homeostasis. This review discusses the response of the peripheral circulation of humans to acute and chronic dynamic exercise and mechanisms responsible for these responses. This is accomplished in the context of leading the reader on a tour through the peripheral circulation during dynamic exercise. During this tour, we consider what is known about how each vascular bed controls BF during exercise and how these control mechanisms are modified by chronic physical activity/exercise training. The tour ends by comparing responses of the systemic circulation to those of the pulmonary circulation relative to the effects of exercise on the regional distribution of BF and mechanisms responsible for control of resistance/conductance in the systemic and pulmonary circulations.
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Affiliation(s)
- M Harold Laughlin
- Department of Medical Pharmacology and Physiology, and the Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA.
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95
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Jayashankar V, Nguyen MJ, Carr BW, Zheng DC, Rosales JB, Rosales JB, Weiser DC. Protein phosphatase 1 β paralogs encode the zebrafish myosin phosphatase catalytic subunit. PLoS One 2013; 8:e75766. [PMID: 24040418 PMCID: PMC3770619 DOI: 10.1371/journal.pone.0075766] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/19/2013] [Indexed: 12/21/2022] Open
Abstract
Background The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the invivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. Methodology/Principal Findings We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Conclusions/Significance Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required.
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Affiliation(s)
- Vaishali Jayashankar
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Michael J. Nguyen
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Brandon W. Carr
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Dale C. Zheng
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Joseph B. Rosales
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Joshua B. Rosales
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America
- * E-mail:
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96
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Arf guanine nucleotide-exchange factors BIG1 and BIG2 regulate nonmuscle myosin IIA activity by anchoring myosin phosphatase complex. Proc Natl Acad Sci U S A 2013; 110:E3162-70. [PMID: 23918382 DOI: 10.1073/pnas.1312531110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Brefeldin A-inhibited guanine nucleotide-exchange factors BIG1 and BIG2 activate, through their Sec7 domains, ADP ribosylation factors (Arfs) by accelerating the replacement of Arf-bound GDP with GTP for initiation of vesicular transport or activation of specific enzymes that modify important phospholipids. They are also implicated in regulation of cell polarization and actin dynamics for directed migration. Reciprocal coimmunoprecipitation of endogenous HeLa cell BIG1 and BIG2 with myosin IIA was demonstrably independent of Arf guanine nucleotide-exchange factor activity, because effects of BIG1 and BIG2 depletion were reversed by overexpression of the cognate BIG molecule C-terminal sequence that follows the Arf activation site. Selective depletion of BIG1 or BIG2 enhanced specific phosphorylation of myosin regulatory light chain (T18/S19) and F-actin content, which impaired cell migration in Transwell assays. Our data are clear evidence of these newly recognized functions for BIG1 and BIG2 in transduction or integration of mechanical signals from integrin adhesions and myosin IIA-dependent actin dynamics. Thus, by anchoring or scaffolding the assembly, organization, and efficient operation of multimolecular myosin phosphatase complexes that include myosin IIA, protein phosphatase 1δ, and myosin phosphatase-targeting subunit 1, BIG1 and BIG2 serve to integrate diverse biophysical and biochemical events in cells.
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97
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The 2-arachidonoylglycerol effect on myosin light chain phosphorylation in human platelets. Biochimie 2013; 95:1620-8. [DOI: 10.1016/j.biochi.2013.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/10/2013] [Indexed: 12/13/2022]
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98
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Yamamoto S, Bayat V, Bellen HJ, Tan C. Protein phosphatase 1ß limits ring canal constriction during Drosophila germline cyst formation. PLoS One 2013; 8:e70502. [PMID: 23936219 PMCID: PMC3723691 DOI: 10.1371/journal.pone.0070502] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 06/20/2013] [Indexed: 12/15/2022] Open
Abstract
Germline cyst formation is essential for the propagation of many organisms including humans and flies. The cytoplasm of germline cyst cells communicate with each other directly via large intercellular bridges called ring canals. Ring canals are often derived from arrested contractile rings during incomplete cytokinesis. However how ring canal formation, maintenance and growth are regulated remains unclear. To better understand this process, we carried out an unbiased genetic screen in Drosophila melanogaster germ cells and identified multiple alleles of flapwing (flw), a conserved serine/threonine-specific protein phosphatase. Flw had previously been reported to be unnecessary for early D. melanogaster oogenesis using a hypomorphic allele. We found that loss of Flw leads to over-constricted nascent ring canals and subsequently tiny mature ring canals, through which cytoplasmic transfer from nurse cells to the oocyte is impaired, resulting in small, non-functional eggs. Flw is expressed in germ cells undergoing incomplete cytokinesis, completely colocalized with the Drosophila myosin binding subunit of myosin phosphatase (DMYPT). This colocalization, together with genetic interaction studies, suggests that Flw functions together with DMYPT to negatively regulate myosin activity during ring canal formation. The identification of two subunits of the tripartite myosin phosphatase as the first two main players required for ring canal constriction indicates that tight regulation of myosin activity is essential for germline cyst formation and reproduction in D. melanogaster and probably other species as well.
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Affiliation(s)
- Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
| | - Vafa Bayat
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Change Tan
- Division of Biological Sciences, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- * E-mail:
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He W, Qiao Y, Peng Y, Zha J, Zhang C, Chen C, Chen C, Wang P, Yang X, Li C, Kamm KE, Stull JT, Zhu M. Altered contractile phenotypes of intestinal smooth muscle in mice deficient in myosin phosphatase target subunit 1. Gastroenterology 2013; 144:1456-65, 1465.e1-5. [PMID: 23499953 PMCID: PMC3782749 DOI: 10.1053/j.gastro.2013.02.045] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 01/31/2013] [Accepted: 02/05/2013] [Indexed: 01/02/2023]
Abstract
BACKGROUND & AIMS The regulatory subunit of myosin light chain phosphatase, MYPT1, has been proposed to control smooth muscle contractility by regulating phosphorylation of the Ca(2+)-dependent myosin regulatory light chain. We generated mice with a smooth muscle-specific deletion of MYPT1 to investigate its physiologic role in intestinal smooth muscle contraction. METHODS We used the Cre-loxP system to establish Mypt1-floxed mice, with the promoter region and exon 1 of Mypt1 flanked by 2 loxP sites. These mice were crossed with SMA-Cre transgenic mice to generate mice with smooth muscle-specific deletion of MYPT1 (Mypt1(SMKO) mice). The phenotype was assessed by histologic, biochemical, molecular, and physiologic analyses. RESULTS Young adult Mypt1(SMKO) mice had normal intestinal motility in vivo, with no histologic abnormalities. On stimulation with KCl or acetylcholine, intestinal smooth muscles isolated from Mypt1(SMKO) mice produced robust and increased sustained force due to increased phosphorylation of the myosin regulatory light chain compared with muscle from control mice. Additional analyses of contractile properties showed reduced rates of force development and relaxation, and decreased shortening velocity, compared with muscle from control mice. Permeable smooth muscle fibers from Mypt1(SMKO) mice had increased sensitivity and contraction in response to Ca(2+). CONCLUSIONS MYPT1 is not essential for smooth muscle function in mice but regulates the Ca(2+) sensitivity of force development and contributes to intestinal phasic contractile phenotype. Altered contractile responses in isolated tissues could be compensated by adaptive physiologic responses in vivo, where gut motility is affected by lower intensities of smooth muscle stimulation for myosin phosphorylation and force development.
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Affiliation(s)
- Wei–Qi He
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Yan–Ning Qiao
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Ya–Jing Peng
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Juan–Min Zha
- Department of Gerontology, The First Hospital Affiliated with Nanjing Medical University, Nanjing, China
| | - Cheng–Hai Zhang
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Chen Chen
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Cai–Ping Chen
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Pei Wang
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China
| | - Xiao Yang
- State Key Laboratory of Proteomics, Genetic Laboratory of Development and Disease, Institute of Biotechnology, Beijing, China
| | - Chao–Jun Li
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China,School of Medicine, Nanjing University, Nanjing, China
| | - Kristine E. Kamm
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - James T. Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Min–Sheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing, China,Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, School of Life Sciences, Wenzhou Medical College, Wenzhou, China
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Gao N, Huang J, He W, Zhu M, Kamm KE, Stull JT. Signaling through myosin light chain kinase in smooth muscles. J Biol Chem 2013; 288:7596-7605. [PMID: 23362260 DOI: 10.1074/jbc.m112.427112] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) phosphorylates smooth muscle myosin regulatory light chain (RLC) to initiate contraction. We used a tamoxifen-activated, smooth muscle-specific inactivation of MLCK expression in adult mice to determine whether MLCK was differentially limiting in distinct smooth muscles. A 50% decrease in MLCK in urinary bladder smooth muscle had no effect on RLC phosphorylation or on contractile responses, whereas an 80% decrease resulted in only a 20% decrease in RLC phosphorylation and contractile responses to the muscarinic agonist carbachol. Phosphorylation of the myosin light chain phosphatase regulatory subunit MYPT1 at Thr-696 and Thr-853 and the inhibitor protein CPI-17 were also stimulated with carbachol. These results are consistent with the previous findings that activation of a small fraction of MLCK by limiting amounts of free Ca(2+)/calmodulin combined with myosin light chain phosphatase inhibition is sufficient for robust RLC phosphorylation and contractile responses in bladder smooth muscle. In contrast, a 50% decrease in MLCK in aortic smooth muscle resulted in 40% inhibition of RLC phosphorylation and aorta contractile responses, whereas a 90% decrease profoundly inhibited both responses. Thus, MLCK content is limiting for contraction in aortic smooth muscle. Phosphorylation of CPI-17 and MYPT1 at Thr-696 and Thr-853 were also stimulated with phenylephrine but significantly less than in bladder tissue. These results indicate differential contributions of MLCK to signaling. Limiting MLCK activity combined with modest Ca(2+) sensitization responses provide insights into how haploinsufficiency of MLCK may result in contractile dysfunction in vivo, leading to dissections of human thoracic aorta.
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Affiliation(s)
- Ning Gao
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Jian Huang
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Weiqi He
- Model Animal Research Center and Ministry of Education Key Laboratory of Model Animal for Disease Study, Nanjing University, 210061 Nanjing, China
| | - Minsheng Zhu
- Model Animal Research Center and Ministry of Education Key Laboratory of Model Animal for Disease Study, Nanjing University, 210061 Nanjing, China
| | - Kristine E Kamm
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - James T Stull
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390.
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