1
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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2
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Prichard KL, O'Brien NS, Murcia SR, Baker JR, McCluskey A. Role of Clathrin and Dynamin in Clathrin Mediated Endocytosis/Synaptic Vesicle Recycling and Implications in Neurological Diseases. Front Cell Neurosci 2022; 15:754110. [PMID: 35115907 PMCID: PMC8805674 DOI: 10.3389/fncel.2021.754110] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/10/2021] [Indexed: 12/17/2022] Open
Abstract
Endocytosis is a process essential to the health and well-being of cell. It is required for the internalisation and sorting of “cargo”—the macromolecules, proteins, receptors and lipids of cell signalling. Clathrin mediated endocytosis (CME) is one of the key processes required for cellular well-being and signalling pathway activation. CME is key role to the recycling of synaptic vesicles [synaptic vesicle recycling (SVR)] in the brain, it is pivotal to signalling across synapses enabling intracellular communication in the sensory and nervous systems. In this review we provide an overview of the general process of CME with a particular focus on two key proteins: clathrin and dynamin that have a central role to play in ensuing successful completion of CME. We examine these two proteins as they are the two endocytotic proteins for which small molecule inhibitors, often of known mechanism of action, have been identified. Inhibition of CME offers the potential to develop therapeutic interventions into conditions involving defects in CME. This review will discuss the roles and the current scope of inhibitors of clathrin and dynamin, providing an insight into how further developments could affect neurological disease treatments.
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Budai Z, Al-Zaeed N, Szentesi P, Halász H, Csernoch L, Szondy Z, Sarang Z. Impaired Skeletal Muscle Development and Regeneration in Transglutaminase 2 Knockout Mice. Cells 2021; 10:3089. [PMID: 34831312 PMCID: PMC8623654 DOI: 10.3390/cells10113089] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/13/2021] [Accepted: 11/04/2021] [Indexed: 12/25/2022] Open
Abstract
Skeletal muscle regeneration is triggered by local inflammation and is accompanied by phagocytosis of dead cells at the injury site. Efferocytosis regulates the inflammatory program in macrophages by initiating the conversion of their inflammatory phenotype into the healing one. While pro-inflammatory cytokines induce satellite cell proliferation and differentiation into myoblasts, growth factors, such as GDF3, released by healing macrophages drive myoblast fusion and myotube growth. Therefore, improper efferocytosis may lead to impaired muscle regeneration. Transglutaminase 2 (TG2) is a versatile enzyme participating in efferocytosis. Here, we show that TG2 ablation did not alter the skeletal muscle weights or sizes but led to the generation of small size myofibers and to decreased grip force in TG2 null mice. Following cardiotoxin-induced injury, the size of regenerating fibers was smaller, and the myoblast fusion was delayed in the tibialis anterior muscle of TG2 null mice. Loss of TG2 did not affect the efferocytic capacity of muscle macrophages but delayed their conversion to Ly6C-CD206+, GDF3 expressing cells. Finally, TG2 promoted myoblast fusion in differentiating C2C12 myoblasts. These results indicate that TG2 expressed by both macrophages and myoblasts contributes to proper myoblast fusion, and its ablation leads to impaired muscle development and regeneration in mice.
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Affiliation(s)
- Zsófia Budai
- Doctoral School of Molecular Cell and Immune Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.B.); (N.A.-Z.); (H.H.)
| | - Nour Al-Zaeed
- Doctoral School of Molecular Cell and Immune Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.B.); (N.A.-Z.); (H.H.)
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (P.S.); (L.C.)
| | - Hajnalka Halász
- Doctoral School of Molecular Cell and Immune Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (Z.B.); (N.A.-Z.); (H.H.)
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (P.S.); (L.C.)
| | - Zsuzsa Szondy
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
- Division of Dental Biochemistry, Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Zsolt Sarang
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
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Kitakaze T, Yoshikawa M, Kobayashi Y, Kimura N, Goshima N, Ishikawa T, Ogata Y, Yamashita Y, Ashida H, Harada N, Yamaji R. Extracellular transglutaminase 2 induces myotube hypertrophy through G protein-coupled receptor 56. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118563. [PMID: 31666191 DOI: 10.1016/j.bbamcr.2019.118563] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 12/15/2022]
Abstract
Skeletal muscle secretes biologically active proteins that contribute to muscle hypertrophy in response to either exercise or dietary intake. The identification of skeletal muscle-secreted proteins that induces hypertrophy can provide critical information regarding skeletal muscle health. Dietary provitamin A, β-carotene, induces hypertrophy of the soleus muscle in mice. Here, we hypothesized that skeletal muscle produces hypertrophy-inducible secretory proteins via dietary β-carotene. Knockdown of retinoic acid receptor (RAR) γ inhibited the β-carotene-induced increase soleus muscle mass in mice. Using RNA sequencing, bioinformatic analyses, and literature searching, we predicted transglutaminase 2 (TG2) to be an all-trans retinoic acid (ATRA)-induced secretory protein in cultured C2C12 myotubes. Tg2 mRNA expression increased in ATRA- or β-carotene-stimulated myotubes and in the soleus muscle of β-carotene-treated mice. Knockdown of RARγ inhibited β-carotene-increased mRNA expression of Tg2 in the soleus muscle. ATRA increased endogenous TG2 levels in conditioned medium from myotubes. Extracellular TG2 promoted the phosphorylation of Akt, mechanistic target of rapamycin (mTOR), and ribosomal p70 S6 kinase (p70S6K), and inhibitors of mTOR, phosphatidylinositol 3-kinase, and Src (rapamycin, LY294002, and Src I1, respectively) inhibited TG2-increased phosphorylation of mTOR and p70S6K. Furthermore, extracellular TG2 promoted protein synthesis and hypertrophy in myotubes. TG2 mutant lacking transglutaminase activity exerted the same effects as wild-type TG2. Knockdown of G protein-coupled receptor 56 (GPR56) inhibited the effects of TG2 on mTOR signaling, protein synthesis, and hypertrophy. These results indicated that TG2 expression was upregulated through ATRA-mediated RARγ and that extracellular TG2 induced myotube hypertrophy by activating mTOR signaling-mediated protein synthesis through GPR56, independent of transglutaminase activity.
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MESH Headings
- Animals
- Cell Enlargement/drug effects
- Cell Line
- GTP-Binding Proteins/genetics
- GTP-Binding Proteins/metabolism
- Insulin-Like Growth Factor I/genetics
- Insulin-Like Growth Factor I/metabolism
- Mice
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Myoblasts/cytology
- Myoblasts/metabolism
- Phosphorylation/drug effects
- Protein Glutamine gamma Glutamyltransferase 2
- Proto-Oncogene Proteins c-akt/metabolism
- RNA Interference
- RNA, Small Interfering/metabolism
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Retinoic Acid/antagonists & inhibitors
- Receptors, Retinoic Acid/genetics
- Receptors, Retinoic Acid/metabolism
- Retinoic Acid Receptor alpha/antagonists & inhibitors
- Retinoic Acid Receptor alpha/genetics
- Retinoic Acid Receptor alpha/metabolism
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- Signal Transduction/drug effects
- TOR Serine-Threonine Kinases/metabolism
- Transglutaminases/genetics
- Transglutaminases/metabolism
- Tretinoin/pharmacology
- beta Carotene/administration & dosage
- beta Carotene/pharmacology
- Retinoic Acid Receptor gamma
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Affiliation(s)
- Tomoya Kitakaze
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan; Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Miki Yoshikawa
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Yasuyuki Kobayashi
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Naohiro Kimura
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Naoki Goshima
- National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Takahiro Ishikawa
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Shimane, Japan
| | - Yoshiyuki Ogata
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Yoko Yamashita
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Hitoshi Ashida
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Naoki Harada
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan
| | - Ryoichi Yamaji
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan.
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5
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Zhao J, Stenzel MH. Entry of nanoparticles into cells: the importance of nanoparticle properties. Polym Chem 2018. [DOI: 10.1039/c7py01603d] [Citation(s) in RCA: 228] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Knowledge of the interactions between nanoparticles (NPs) and cell membranes is of great importance for the design of safe and efficient nanomedicines.
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Affiliation(s)
- Jiacheng Zhao
- Centre for Advanced Macromolecular Design
- The University of New South Wales
- Sydney
- Australia
- School of Chemical Engineering
| | - Martina H. Stenzel
- Centre for Advanced Macromolecular Design
- The University of New South Wales
- Sydney
- Australia
- School of Chemistry
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6
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Price D, Ackland ML, Suphioglu C. Identifying Epithelial Endocytotic Mechanisms of the Peanut Allergens Ara h 1 and Ara h 2. Int Arch Allergy Immunol 2017; 172:106-115. [DOI: 10.1159/000451085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/27/2016] [Indexed: 01/08/2023] Open
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Dutta D, Donaldson JG. Search for inhibitors of endocytosis: Intended specificity and unintended consequences. CELLULAR LOGISTICS 2014; 2:203-208. [PMID: 23538558 PMCID: PMC3607622 DOI: 10.4161/cl.23967] [Citation(s) in RCA: 326] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We discuss here the variety of approaches that have been taken to inhibit different forms of endocytosis. Typically, both non-specific and specific chemical inhibitors of endocytosis are tried in order to “classify” entry of a new plasma membrane protein into one of the various types of endocytosis. This classification can be confirmed through genetic approaches of protein depletion or overexpression of mutants of known endocytosis machinery components. Although some new compounds have been designed to be selective in biochemical assays, we caution investigators to be alert to the unintended consequences that sometimes arise when these compounds are applied to intact cells.
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Affiliation(s)
- Dipannita Dutta
- Cell Biology & Physiology Center; National Heart, Lung, and Blood Institute; National Institutes of Health; Bethesda, MD USA
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8
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Eckert RL, Kaartinen MT, Nurminskaya M, Belkin AM, Colak G, Johnson GVW, Mehta K. Transglutaminase regulation of cell function. Physiol Rev 2014; 94:383-417. [PMID: 24692352 DOI: 10.1152/physrev.00019.2013] [Citation(s) in RCA: 289] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Transglutaminases (TGs) are multifunctional proteins having enzymatic and scaffolding functions that participate in regulation of cell fate in a wide range of cellular systems and are implicated to have roles in development of disease. This review highlights the mechanism of action of these proteins with respect to their structure, impact on cell differentiation and survival, role in cancer development and progression, and function in signal transduction. We also discuss the mechanisms whereby TG level is controlled and how TGs control downstream targets. The studies described herein begin to clarify the physiological roles of TGs in both normal biology and disease states.
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9
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Ivanov AI. Pharmacological inhibition of endocytic pathways: is it specific enough to be useful? Methods Mol Biol 2008; 440:15-33. [PMID: 18369934 DOI: 10.1007/978-1-59745-178-9_2] [Citation(s) in RCA: 453] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Eukaryotic cells constantly form and internalize plasma membrane vesicles in a process known as endocytosis. Endocytosis serves a variety of housekeeping and specialized cellular functions, and it can be mediated by distinct molecular pathways. Among them, internalization via clathrin-coated pits, lipid raft/caveolae-mediated endocytosis and macropinocytosis/phagocytosis are the most extensively characterized. The major endocytic pathways are usually distinguished on the basis of their differential sensitivity to pharmacological/chemical inhibitors, although the possibility of nonspecific effects of such inhibitors is frequently overlooked. This review provides a critical evaluation of the selectivity of the most widely used pharmacological inhibitors of clathrin-mediated, lipid raft/caveolae-mediated endocytosis and macropinocytosis/phagocytosis. The mechanisms of actions of these agents are described with special emphasis on their reported side effects on the alternative internalization modes and the actin cytoskeleton. The most and the least-selective inhibitors of each major endocytic pathway are highlighted.
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Affiliation(s)
- Andrei I Ivanov
- Department of Medicine, Gastroenterology and Hepatology Division, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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10
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McGrath MJ, Cottle DL, Nguyen MA, Dyson JM, Coghill ID, Robinson PA, Holdsworth M, Cowling BS, Hardeman EC, Mitchell CA, Brown S. Four and a half LIM protein 1 binds myosin-binding protein C and regulates myosin filament formation and sarcomere assembly. J Biol Chem 2006; 281:7666-83. [PMID: 16407297 DOI: 10.1074/jbc.m512552200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Four and a half LIM protein 1 (FHL1/SLIM1) is highly expressed in skeletal and cardiac muscle; however, the function of FHL1 remains unknown. Yeast two-hybrid screening identified slow type skeletal myosin-binding protein C as an FHL1 binding partner. Myosin-binding protein C is the major myosin-associated protein in striated muscle that enhances the lateral association and stabilization of myosin thick filaments and regulates actomyosin interactions. The interaction between FHL1 and myosin-binding protein C was confirmed using co-immunoprecipitation of recombinant and endogenous proteins. Recombinant FHL2 and FHL3 also bound myosin-binding protein C. FHL1 impaired co-sedimentation of myosin-binding protein C with reconstituted myosin filaments, suggesting FHL1 may compete with myosin for binding to myosin-binding protein C. In intact skeletal muscle and isolated myofibrils, FHL1 localized to the I-band, M-line, and sarcolemma, co-localizing with myosin-binding protein C at the sarcolemma in intact skeletal muscle. Furthermore, in isolated myofibrils FHL1 staining at the M-line appeared to extend partially into the C-zone of the A-band, where it co-localized with myosin-binding protein C. Overexpression of FHL1 in differentiating C2C12 cells induced "sac-like" myotube formation (myosac), associated with impaired Z-line and myosin thick filament assembly. This phenotype was rescued by co-expression of myosin-binding protein C. FHL1 knockdown using RNAi resulted in impaired myosin thick filament formation associated with reduced incorporation of myosin-binding protein C into the sarcomere. This study identified FHL1 as a novel regulator of myosin-binding protein C activity and indicates a role for FHL1 in sarcomere assembly.
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Affiliation(s)
- Meagan J McGrath
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
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11
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Aeschlimann D, Thomazy V. Protein crosslinking in assembly and remodelling of extracellular matrices: the role of transglutaminases. Connect Tissue Res 2000; 41:1-27. [PMID: 10826705 DOI: 10.3109/03008200009005638] [Citation(s) in RCA: 244] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Transglutaminases form a family of proteins that have evolved for specialized functions such as protein crosslinking in haemostasis, semen coagulation, or keratinocyte cornified envelope formation. In contrast to the other members of this protein family, tissue transglutaminase is a multifunctional enzyme apparently involved in very disparate biological processes. By virtue of its reciprocal Ca2+-dependent crosslinking activity or GTP-dependent signal transducing activity, tissue transglutaminase exhibits true multifunctionality at the molecular level. The crosslinking activity can subserve disparate biological phenomena depending on the location of the target proteins. Intracellular activation of tissue transglutaminase can give rise to crosslinked protein envelopes in apoptotic cells, whereas extracellular activation contributes to stabilization of the extracellular matrix and promotes cell-substrate interaction. While tissue transglutaminase synthesis and activation is normally part of a protective cellular response contributing to tissue homeostasis, the enzyme has also been implicated in a number of pathological conditions including fibrosis, atherosclerosis, neurodegenerative diseases, celiac disease, and cancer metastasis. This review discusses the role of transglutaminases in extracellular matrix crosslinking with a focus on the multifunctional enzyme tissue transglutaminase.
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Affiliation(s)
- D Aeschlimann
- Division of Orthopedic Surgery, University of Wisconsin, Clinical Science Center, Madison 53792, USA
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12
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Kun Kim D, Kyung Hong E, Ho Lee K, Il Kim J, Keun Song W. Molecular cloning and expression of nitric oxide synthase gene in chick embryonic muscle cells. Cell Biochem Funct 1999; 17:261-70. [PMID: 10587613 DOI: 10.1002/(sici)1099-0844(199912)17:4<261::aid-cbf838>3.0.co;2-t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The chick skeletal muscle nitric oxide synthase (NOS) gene was cloned in order to further define the involvement of NOS in the differentiation of skeletal muscle cells. The respective cDNA had an open reading frame of 1136 amino acid residues, predicting a protein of 129,709.85 Da, and recognition sites for FAD, FMN, NADPH, and a calmodulin-binding site like those of other mammalian NOS's. Alignment of the deduced amino acid sequence revealed high homology with mammalian inducible NOS (iNOS), but not other NOS isoforms, suggesting chick skeletal muscle NOS may be an iNOS isoform. Immunoblots showed that NOS expression was highly restricted in embryonic muscle, but not in adult skeletal muscle: NOS expression markedly increased from embryonic day 9, reached a maximum by embryonic day 13, and then gradually declined until it was no longer detectable on embryonic day 19. When muscle cells obtained on embryonic day 12 were cultured, NOS expression increased transiently prior to the onset of differentiation and decreased thereafter. Inhibition of NOS expression by PDTC completely prevented muscle cell differentiation, as indicated by the inhibition of expression of myosin heavy chain and creatine kinase. The inhibitory effect of PDTC was completely reversed by addition of sodium nitroprusside, a compound that produces NO. These results clearly indicate that NOS is significantly involved in the differentiation of chick skeletal muscle cells.
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Affiliation(s)
- D Kun Kim
- Department of Molecular Biology and Research Center for Cell Differentiation, Seoul National University, Seoul 151-742, Korea
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13
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Abstract
Autoimmune diseases are characterized by multiple autoantibodies and/or autoreactive T cells that recognize a large number of antigens. Many of these antigens undergo extensive post-translational modifications during apoptosis and act as substrates for the proapoptotic cystein proteases. Here, Mauro Piacentini and Vittorio Colizzi discuss the effects on autoimmunity produced by post-translational modifications of proteins catalysed by the proapoptotic enzyme tissue transglutaminase.
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Affiliation(s)
- M Piacentini
- Dept of Biology, University of Rome Tor Vergata, Italy.
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14
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Gorza L, Menabó R, Di Lisa F, Vitadello M. Troponin T cross-linking in human apoptotic cardiomyocytes. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 150:2087-97. [PMID: 9176400 PMCID: PMC1858314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Intracellular calcium overload of guinea pig cardiomyocytes is accompanied by troponin T cross-linking, which is revealed by changes in immunoreactivity of anti-troponin T antibodies. We presently investigated whether the same process is detectable in the human heart. Immunohistochemistry shows myofibrillar staining with BN-59 anti-troponin T antibody with rare cardiomyocytes in samples obtained at surgery, whereas approximately 50% of myocytes are labeled in heart samples taken at autopsy within 3 hours of death, and every cardiomyocyte is stained after exposure of biopsy sections to 10 mmol/L calcium. Western blot analysis shows reactive polypeptides of approximately 70 and 85 to 90 kd in addition to troponin T in both treated and autopsy heart sections. Neither reactivity in immunohistochemistry nor additional reactive polypeptides in Western blot are detectable when calpain or transglutaminase is inhibited during exposure of sections to high calcium. Troponin T crosslinking occurs also in isolated myofibrils, which show staining with BN-59 at either sarcomeric A or I bands. Labeling with TdT-mediated dUTP nick and labeling (TUNEL) to demonstrate apoptosis reveals DNA fragmentation in BN-59-positive myocytes. Thus, troponin T cross-linking occurs in human cardiac myocytes concomitantly with apoptosis and autopsy autolysis, suggesting that similar cytosolic alterations can be produced by different types of myocyte death.
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Affiliation(s)
- L Gorza
- CNR-Unit for Muscle Biology, University of Padova, Italy
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15
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Lee KH, Kim DG, Shin NY, Song WK, Kwon H, Chung CH, Kang MS. NF-kappaB-dependent expression of nitric oxide synthase is required for membrane fusion of chick embryonic myoblasts. Biochem J 1997; 324 ( Pt 1):237-42. [PMID: 9164862 PMCID: PMC1218422 DOI: 10.1042/bj3240237] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The activity of nitric oxide synthase (NOS) has recently been shown to increase transiently but dramatically in chick embryonic myoblasts that are competent for fusion and that NO acts as a messenger for the cell fusion. Here we show that the rise in NOS activity is tightly correlated with an increase in NOS protein level, and its synthesis is under transcriptional control. In addition, a partial cDNA sequence of NOS obtained by reverse transcription PCR on total RNA from chick myoblasts was found to be identical with that of the inducible type of NOS (iNOS) from chick macrophage. Thus chick myoblast NOS must belong to the family of iNOS. Consistently, pyrrolidine dithiocarbamate, a potent inhibitor of nuclear factor kappaB (NF-kappaB), prevented the expression of myoblast NOS. Furthermore the antioxidant also strongly inhibited cell fusion, and its inhibitory effect was reversed by treatment with sodium nitroprusside, an NO-generating agent. In addition, nuclear extracts obtained from myoblasts that were competent for fusion, but not those from proliferating cells or from fully differentiated myotubes, were capable of binding to the consensus NF-kappaB site in the promoter region of the gene encoding iNOS. These results suggest that NF-kappaB-dependent expression of NOS is an important step in membrane fusion of chick embryonic myoblasts.
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Affiliation(s)
- K H Lee
- Department of Molecular Biology and Research Center for Cell Differentiation, Seoul National University, Seoul 151-742, Korea
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