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Can Blebbistatin block the hypertrophy status in the zebrafish exvivo cardiac model? Biochim Biophys Acta Mol Basis Dis 2022; 1868:166471. [PMID: 35750268 DOI: 10.1016/j.bbadis.2022.166471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/31/2022] [Accepted: 06/16/2022] [Indexed: 11/23/2022]
Abstract
Ex-vivo simple models are powered tools to study cardiac hypertrophy. It is possible to control the activation of critical genes and thus test the effects of drug therapies before the in vivo tests. A zebrafish cardiac hypertrophy developed by 500 μM phenylephrine (PE) treatment in ex vivo culture has been demonstrated to activate the essential expression of the embryonal genes. These genes are the same as those described in several previous pieces of research on hypertrophic pathology in humans. The efficacy of the chemical drug Blebbistatin (BL) on hypertrophy induced ex vivo cultured hearts is studied in this research. BL can inhibit the myosins and the calcium wave in counteracting the hypertrophy status caused by PE. Samples treated with PE, BL and PE simultaneously, or pre/post-treatment with BL, have been analysed for the embryonal gene activation concerning the hypertrophy status. The qRTPCR has shown an inhibitory effect of BL treatments on the microRNAs downregulation with the consequent low expression of essential embryonal genes. In particular, BL seems to be effective in blocking the hyperplasia of the epicardium but less effective in myocardium hypertrophy. The model can make it possible to obtain knowledge on the transduction pathways activated by BL and investigate the potential use of this drug in treating cardiac hypertrophy in humans.
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2
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Błaszczyk M, Gajewska M, Dymowska M, Majewska A, Domoradzki T, Prostek A, Pingwara R, Hulanicka M, Grzelkowska-Kowalczyk K. Interleukin-6 mimics insulin-dependent cellular distribution of some cytoskeletal proteins and Glut4 transporter without effect on glucose uptake in 3T3-L1 adipocytes. Histochem Cell Biol 2022; 157:525-546. [PMID: 35230485 DOI: 10.1007/s00418-022-02091-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2022] [Indexed: 11/04/2022]
Abstract
Interleukin (IL)-6, a known proinflammatory cytokine, is released in both visceral adipose tissue and contracting skeletal muscle. In this study, we used microRNA profiling as a screening method to identify miRNA species modified by IL-6 treatment in mouse 3T3-L1 adipocytes. miRNA microarray analysis and qRT-PCR revealed increased expression of miR-146b-3p in adipocytes exposed to IL-6 (1 ng/ml) during 8-day differentiation. On the basis of ontological analysis of potential targets, selected proteins associated with cytoskeleton and transport were examined in the context of adipocyte response to insulin, using immunofluorescence and confocal microscopy. We concluded that IL-6: (i) does not affect insulin action on actin cellular distribution; (ii) modulates the effect of insulin on myosin light chain kinase (Mylk) distribution by preventing its shift toward cytoplasm; (iii) mimics the effect of insulin on dynein distribution by increasing its near-nuclear accumulation; (iv) mimics the effect of insulin on glucose transporter Glut4 distribution, especially by increasing its near-nuclear accumulation; (v) supports insulin action on early endosome marker Rab4A near-nuclear accumulation. Moreover, as IL-6 did not disturb insulin-dependent glucose uptake, our results do not confirm the IL-6-induced impairment of insulin action observed in some in vitro studies, suggesting that the effect of IL-6 is dose dependent.
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Affiliation(s)
- Maciej Błaszczyk
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Małgorzata Gajewska
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Marta Dymowska
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Alicja Majewska
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Tomasz Domoradzki
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Adam Prostek
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Rafał Pingwara
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Magdalena Hulanicka
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Katarzyna Grzelkowska-Kowalczyk
- Department of Physiological Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-776, Warsaw, Poland.
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Kislev N, Mor-Yossef Moldovan L, Barak R, Egozi M, Benayahu D. MYH10 Governs Adipocyte Function and Adipogenesis through Its Interaction with GLUT4. Int J Mol Sci 2022; 23:ijms23042367. [PMID: 35216482 PMCID: PMC8875441 DOI: 10.3390/ijms23042367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 12/10/2022] Open
Abstract
Adipogenesis is dependent on cytoskeletal remodeling that determines and maintains cellular shape and function. Cytoskeletal proteins contribute to the filament-based network responsible for controlling the shape of adipocytes and promoting the intracellular trafficking of cellular components. Currently, the understanding of these mechanisms and their effect on differentiation and adipocyte function remains incomplete. In this study, we identified the non-muscle myosin 10 (MYH10) as a novel regulator of adipogenesis and adipocyte function through its interaction with the insulin-dependent glucose transporter 4 (GLUT4). MYH10 depletion in preadipocytes resulted in impaired adipogenesis, with knockdown cells exhibiting an absence of morphological alteration and molecular signals. MYH10 was shown in a complex with GLUT4 in adipocytes, an interaction regulated by insulin induction. The missing adipogenic capacity of MYH10 knockdown cells was restored when the cells took up GLUT4 vesicles from neighbor wildtype cells in a co-culture system. This signaling cascade is regulated by the protein kinase C ζ (PKCζ), which interacts with MYH10 to modify the localization and interaction of both GLUT4 and MYH10 in adipocytes. Overall, our study establishes MYH10 as an essential regulator of GLUT4 translocation, affecting both adipogenesis and adipocyte function, highlighting its importance in future cytoskeleton-based studies in adipocytes.
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Romani P, Valcarcel-Jimenez L, Frezza C, Dupont S. Crosstalk between mechanotransduction and metabolism. Nat Rev Mol Cell Biol 2021; 22:22-38. [PMID: 33188273 DOI: 10.1038/s41580-020-00306-w] [Citation(s) in RCA: 183] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2020] [Indexed: 12/22/2022]
Abstract
Mechanical forces shape cells and tissues during development and adult homeostasis. In addition, they also signal to cells via mechanotransduction pathways to control cell proliferation, differentiation and death. These processes require metabolism of nutrients for both energy generation and biosynthesis of macromolecules. However, how cellular mechanics and metabolism are connected is still poorly understood. Here, we discuss recent evidence indicating how the mechanical cues exerted by the extracellular matrix (ECM), cell-ECM and cell-cell adhesion complexes influence metabolic pathways. Moreover, we explore the energy and metabolic requirements associated with cell mechanics and ECM remodelling, implicating a reciprocal crosstalk between cell mechanics and metabolism.
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Affiliation(s)
- Patrizia Romani
- Department of Molecular Medicine, University of Padua Medical School, Padua, Italy
| | | | - Christian Frezza
- MRC Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Cambridge, UK.
| | - Sirio Dupont
- Department of Molecular Medicine, University of Padua Medical School, Padua, Italy.
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5
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Inoue H, Inazu M, Konishi M, Yokoyama U. Functional expression of TRPM7 as a Ca 2+ influx pathway in adipocytes. Physiol Rep 2020; 7:e14272. [PMID: 31650715 PMCID: PMC6813326 DOI: 10.14814/phy2.14272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 09/20/2019] [Accepted: 10/04/2019] [Indexed: 02/01/2023] Open
Abstract
In adipocytes, intracellular Ca2+ and Mg2+ modulates physiological functions, such as insulin action and the secretion of adipokines. TRPM7 is a Ca2+/Mg2+‐permeable non‐selective cation channel. TRPM7 mRNA is highly expressed in adipose tissue, however, its functional expression in adipocytes remains to be elucidated. In this study, we demonstrated for the first time that TRPM7 was functionally expressed in both freshly isolated white adipocytes and in 3T3‐L1 adipocytes differentiated from a 3T3‐L1 pre‐adipocyte cell line by whole‐cell patch‐clamp recordings. Consistent with known properties of TRPM7 current, the current in adipocytes was activated by the elimination of extracellular divalent cations and the reduction of intracellular free Mg2+ concentrations, and was inhibited by the TRPM7 inhibitors, 2‐aminoethyl diphenylborinate (2‐APB), hydrogen peroxide (H2O2), N‐methyl maleimide (NMM), NS8593, and 2‐amino‐2‐[2‐(4‐octylphenyl)ethyl]‐1,3‐propanediol (FTY720). Treatment with small‐interfering (si) RNA targeting TRPM7 resulted in a reduction in the current to 23 ± 7% of nontargeting siRNA‐treated adipocytes. Moreover a TRPM7 activator, naltriben, increased the TRPM7‐like current and [Ca2+]i in 3T3‐L1 adipocytes but not in TRPM7‐knockdown adipocytes. These findings indicate that TRPM7 is functionally expressed, and plays a role as a Ca2+ influx pathway in adipocytes.
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Affiliation(s)
- Hana Inoue
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Masato Inazu
- Institute of Medical Science, Tokyo Medical University, Tokyo, Japan
| | - Masato Konishi
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Utako Yokoyama
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
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6
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Crajoinas RO, Polidoro JZ, Girardi ACC. The potential role of myosin motor proteins in mediating the subcellular distribution of NHE3 in the renal proximal tubule. Am J Physiol Renal Physiol 2019; 316:F986-F992. [PMID: 30864843 DOI: 10.1152/ajprenal.00577.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Isoform 3 of the Na+/H+ exchanger (NHE3) is responsible for the majority of the reabsorption of NaCl, NaHCO3, and, consequently, water in the renal proximal tubule. As such, this transporter plays an essential role in acid-base balance and extracellular fluid volume homeostasis and determining systemic arterial blood pressure levels. NHE3 activity is modulated by a number of mechanisms, including the redistribution of the transporter between the body of the microvilli (where NHE3 is active) and the base of the microvilli (where NHE3 is less active). Although the physiological, pathophysiological, and pharmacological importance of the subcellular distribution of NHE3 has been well established, the exact mechanism whereby NHE3 is translocated along microvilli microdomains of the proximal tubule apical membrane is unknown. Nonmuscle myosin IIA and unconventional myosin VI move cargoes in anterograde and retrograde directions, respectively, and are known to redistribute along with NHE3 in the proximal tubule in response to a variety of natriuretic and antinatriuretic stimuli, including stimulation or inhibition of the renin-angiotensin system, high dietary Na+ intake, and high blood pressure. Therefore, this review aims to discuss the current evidence that suggests a potential role of myosin IIA and myosin VI in mediating the subcellular distribution of NHE3 along the kidney proximal tubule microvilli and their possible contribution in modifying NHE3-mediated Na+ reabsorption under both physiological and pathophysiological conditions.
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Affiliation(s)
- Renato O Crajoinas
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
| | - Juliano Z Polidoro
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
| | - Adriana C C Girardi
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
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Wasik AA, Dash SN, Lehtonen S. Septins in kidney: A territory little explored. Cytoskeleton (Hoboken) 2018; 76:154-162. [PMID: 30004646 PMCID: PMC6585700 DOI: 10.1002/cm.21477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/15/2018] [Accepted: 07/03/2018] [Indexed: 12/15/2022]
Abstract
Septins are a conserved family of GTP‐binding proteins that assemble into cytoskeletal filaments to function in a highly sophisticated and physiologically regulated manner. Originally septins were discovered in the budding yeast as membrane‐associated filaments that affect cell polarity and cytokinesis. In the last decades, much progress has been made in understanding the biochemical properties and cell biological functions of septins. In line with this, mammalian septins have been shown to be involved in various cellular processes, including regulation of cell polarity, cytoskeletal organization, vesicle trafficking, ciliogenesis, and cell–pathogen interactions. A growing number of studies have shown that septins play important roles in tissue and organ development and physiology; yet, little is known about their role in the kidney. In the following review, we discuss the structure and functions of septins in general and summarize the evidence for their presence and roles in the kidney.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Surjya N Dash
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland
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8
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Wasik AA, Lehtonen S. Glucose Transporters in Diabetic Kidney Disease-Friends or Foes? Front Endocrinol (Lausanne) 2018; 9:155. [PMID: 29686650 PMCID: PMC5900043 DOI: 10.3389/fendo.2018.00155] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/22/2018] [Indexed: 12/16/2022] Open
Abstract
Diabetic kidney disease (DKD) is a major microvascular complication of diabetes and a common cause of end-stage renal disease worldwide. DKD manifests as an increased urinary protein excretion (albuminuria). Multiple studies have shown that insulin resistance correlates with the development of albuminuria in non-diabetic and diabetic patients. There is also accumulating evidence that glomerular epithelial cells or podocytes are insulin sensitive and that insulin signaling in podocytes is essential for maintaining normal kidney function. At the cellular level, the mechanisms leading to the development of insulin resistance include mutations in the insulin receptor gene, impairments in the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway, or perturbations in the trafficking of glucose transporters (GLUTs), which mediate the uptake of glucose into cells. Podocytes express several GLUTs, including GLUT1, GLUT2, GLUT3, GLUT4, and GLUT8. Of these, the most studied ones are GLUT1 and GLUT4, both shown to be insulin responsive in podocytes. In the basal state, GLUT4 is preferentially located in perinuclear and cytosolic vesicular structures and to a lesser extent at the plasma membrane. After insulin stimulation, GLUT4 is sorted into GLUT4-containing vesicles (GCVs) that translocate to the plasma membrane. GCV trafficking consists of several steps, including approaching of the GCVs to the plasma membrane, tethering, and docking, after which the lipid bilayers of the GCVs and the plasma membrane fuse, delivering GLUT4 to the cell surface for glucose uptake into the cell. Studies have revealed novel molecular regulators of the GLUT trafficking in podocytes and unraveled unexpected roles for GLUT1 and GLUT4 in the development of DKD, summarized in this review. These findings pave the way for better understanding of the mechanistic pathways associated with the development and progression of DKD and aid in the development of new treatments for this devastating disease.
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Bedi D, Dennis JC, Morrison EE, Braden TD, Judd RL. Regulation of intracellular trafficking and secretion of adiponectin by myosin II. Biochem Biophys Res Commun 2017; 490:202-208. [PMID: 28606474 DOI: 10.1016/j.bbrc.2017.06.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 06/07/2017] [Indexed: 01/08/2023]
Abstract
Adiponectin is a protein secreted by white adipocytes that plays an important role in insulin action, energy homeostasis and the development of atherosclerosis. The intracellular localization and trafficking of GLUT4 and leptin in adipocytes has been well studied, but little is known regarding the intracellular trafficking of adiponectin. Recent studies have demonstrated that constitutive adiponectin secretion is dependent on PIP2 levels and the integrity of cortical F-actin. Non-muscle myosin II is an actin-based motor that is associated with membrane vesicles and participates in vesicular trafficking in mammalian cells. Therefore, we investigated the role of myosin II in the trafficking and secretion of adiponectin in 3T3-L1 adipocytes. Confocal microscopy revealed that myosin IIA and IIB were dispersed throughout the cytoplasm of the adipocyte. Both myosin isoforms were localized in the Golgi/TGN region as evidenced by colocalization with the cis-Golgi marker, p115 and the trans-Golgi marker, γ-adaptin. Inhibition of myosin II activity by blebbistatin or actin depolymerization by latrunculin B dispersed myosin IIA and IIB towards the periphery while significantly inhibiting adiponectin secretion. Therefore, the constitutive trafficking and secretion of adiponectin in 3T3-L1 adipocytes occurs by an actin-dependent mechanism that involves the actin-based motors, myosin IIA and IIB.
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Affiliation(s)
- Deepa Bedi
- Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, United States.
| | - John C Dennis
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Edward E Morrison
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Tim D Braden
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Robert L Judd
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
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10
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Wasik AA, Dumont V, Tienari J, Nyman TA, Fogarty CL, Forsblom C, Lehto M, Lehtonen E, Groop PH, Lehtonen S. Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion. Exp Cell Res 2016; 350:336-348. [PMID: 28011197 PMCID: PMC5243148 DOI: 10.1016/j.yexcr.2016.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/10/2016] [Accepted: 12/17/2016] [Indexed: 12/28/2022]
Abstract
Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Vincent Dumont
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, 05850 Hyvinkää, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Christopher L Fogarty
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Carol Forsblom
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Eero Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland; Laboratory Animal Centre, University of Helsinki, 00014 Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland; Baker IDI Heart & Diabetes Institute, 3004 Melbourne, Australia
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland.
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11
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Hatakeyama H, Nakahata Y, Yarimizu H, Kanzaki M. Live-cell single-molecule labeling and analysis of myosin motors with quantum dots. Mol Biol Cell 2016; 28:173-181. [PMID: 28035048 PMCID: PMC5221621 DOI: 10.1091/mbc.e16-06-0413] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/28/2016] [Accepted: 11/01/2016] [Indexed: 01/07/2023] Open
Abstract
Quantum dots (QDs) are a powerful tool for quantitative biology, but two challenges are associated with using them to track intracellular molecules in live cells. A simple and convenient method is presented for labeling intracellular molecules by using HaloTag technology and electroporation and is used to successfully track myosins within live cells. Quantum dots (QDs) are a powerful tool for quantitatively analyzing dynamic cellular processes by single-particle tracking. However, tracking of intracellular molecules with QDs is limited by their inability to penetrate the plasma membrane and bind to specific molecules of interest. Although several techniques for overcoming these problems have been proposed, they are either complicated or inconvenient. To address this issue, in this study, we developed a simple, convenient, and nontoxic method for labeling intracellular molecules in cells using HaloTag technology and electroporation. We labeled intracellular myosin motors with this approach and tracked their movement within cells. By simultaneously imaging myosin movement and F-actin architecture, we observed that F-actin serves not only as a rail but also as a barrier for myosin movement. We analyzed the effect of insulin on the movement of several myosin motors, which have been suggested to regulate intracellular trafficking of the insulin-responsive glucose transporter GLUT4, but found no significant enhancement in myosin motor motility as a result of insulin treatment. Our approach expands the repertoire of proteins for which intracellular dynamics can be analyzed at the single-molecule level.
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Affiliation(s)
- Hiroyasu Hatakeyama
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8579, Japan .,Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579, Japan
| | - Yoshihito Nakahata
- Department of Information and Intelligent Systems, Tohoku University, Sendai 980-8579, Japan
| | - Hirokazu Yarimizu
- Department of Information and Intelligent Systems, Tohoku University, Sendai 980-8579, Japan
| | - Makoto Kanzaki
- Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579, Japan.,Department of Information and Intelligent Systems, Tohoku University, Sendai 980-8579, Japan
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12
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Trefely S, Khoo PS, Krycer JR, Chaudhuri R, Fazakerley DJ, Parker BL, Sultani G, Lee J, Stephan JP, Torres E, Jung K, Kuijl C, James DE, Junutula JR, Stöckli J. Kinome Screen Identifies PFKFB3 and Glucose Metabolism as Important Regulators of the Insulin/Insulin-like Growth Factor (IGF)-1 Signaling Pathway. J Biol Chem 2015; 290:25834-46. [PMID: 26342081 DOI: 10.1074/jbc.m115.658815] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Indexed: 01/02/2023] Open
Abstract
The insulin/insulin-like growth factor (IGF)-1 signaling pathway (ISP) plays a fundamental role in long term health in a range of organisms. Protein kinases including Akt and ERK are intimately involved in the ISP. To identify other kinases that may participate in this pathway or intersect with it in a regulatory manner, we performed a whole kinome (779 kinases) siRNA screen for positive or negative regulators of the ISP, using GLUT4 translocation to the cell surface as an output for pathway activity. We identified PFKFB3, a positive regulator of glycolysis that is highly expressed in cancer cells and adipocytes, as a positive ISP regulator. Pharmacological inhibition of PFKFB3 suppressed insulin-stimulated glucose uptake, GLUT4 translocation, and Akt signaling in 3T3-L1 adipocytes. In contrast, overexpression of PFKFB3 in HEK293 cells potentiated insulin-dependent phosphorylation of Akt and Akt substrates. Furthermore, pharmacological modulation of glycolysis in 3T3-L1 adipocytes affected Akt phosphorylation. These data add to an emerging body of evidence that metabolism plays a central role in regulating numerous biological processes including the ISP. Our findings have important implications for diseases such as type 2 diabetes and cancer that are characterized by marked disruption of both metabolism and growth factor signaling.
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Affiliation(s)
- Sophie Trefely
- From the Garvan Institute of Medical Research, Sydney 2010 NSW, Australia
| | - Poh-Sim Khoo
- From the Garvan Institute of Medical Research, Sydney 2010 NSW, Australia, Genentech Inc., South San Francisco, California 94080
| | - James R Krycer
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and
| | - Rima Chaudhuri
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and
| | - Daniel J Fazakerley
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and
| | - Benjamin L Parker
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and
| | - Ghazal Sultani
- From the Garvan Institute of Medical Research, Sydney 2010 NSW, Australia
| | - James Lee
- Genentech Inc., South San Francisco, California 94080
| | | | - Eric Torres
- Genentech Inc., South San Francisco, California 94080
| | - Kenneth Jung
- Genentech Inc., South San Francisco, California 94080
| | | | - David E James
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and the Sydney Medical School, University of Sydney, Sydney 2006 NSW, Australia
| | | | - Jacqueline Stöckli
- the Charles Perkins Centre, School of Molecular Bioscience, University of Sydney, Sydney 2006 NSW, Australia, and
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13
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Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca(2+) release. Mol Metab 2014; 3:742-53. [PMID: 25353002 PMCID: PMC4209358 DOI: 10.1016/j.molmet.2014.07.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/11/2014] [Accepted: 07/16/2014] [Indexed: 12/25/2022] Open
Abstract
Understanding how muscle contraction orchestrates insulin-independent muscle glucose transport may enable development of hyperglycemia-treating drugs. The prevailing concept implicates Ca2+ as a key feed forward regulator of glucose transport with secondary fine-tuning by metabolic feedback signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca2+ release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport during muscle contraction, and call for a major reconsideration of the established Ca2+ centric paradigm.
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da Costa AV, Calábria LK, de Souza Santos P, Goulart LR, Espindola FS. Glibenclamide treatment modulates the expression and localization of myosin-IIB in diabetic rat brain. J Neurol Sci 2014; 340:159-64. [PMID: 24725740 DOI: 10.1016/j.jns.2014.03.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/10/2014] [Accepted: 03/11/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Myosin-IIB is a non-muscle isoform in the brain with increased expression in the brains of diabetic rats. Chronic hyperglycemia caused by diabetes can impair learning and memory. Oral hypoglycemic agents such as glibenclamide have been used to control hyperglycemia. We report changes in the expression and distribution of myosin-IIB in the frontal cortex and hippocampus of diabetic rats treated with glibenclamide. METHODS The brains were removed after 43 days of treatment with glibenclamide (6 mg/kg bw orally), homogenized and analyzed by Western blotting, qRT-PCR and immunohistochemistry. RESULTS Myosin-IIB expression increased in the brains of diabetic rats. However, protein expression returned to control levels when treated with glibenclamide. In addition, the expression of MYH10 gene encoding non-muscle myosin heavy chain-B decreased in diabetic rats treated with glibenclamide. Moreover, we found weak myosin-IIB labeling in the hippocampus and frontal cortex of rats treated with glibenclamide. Therefore, the expression of myosin-IIB is affected by diabetes mellitus and may be modulated by glibenclamide treatment in rats. Structural changes in the hippocampus and prefrontal cortex are reversible, and glibenclamide treatment may reduce the patho-physiological changes in the brain. CONCLUSIONS Our findings can contribute to the understanding of the regulation of myosins in the brains of diabetic rats.
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Affiliation(s)
- Alice Vieira da Costa
- Institute of Genetics and Biochemistry, Federal University of Uberlândia, Campus Umuarama, Uberlândia, MG 38400-902, Brazil
| | - Luciana Karen Calábria
- Institute of Genetics and Biochemistry, Federal University of Uberlândia, Campus Umuarama, Uberlândia, MG 38400-902, Brazil; Faculty of Integrated Sciences, Federal University of Uberlândia, Campus Pontal, Ituiutaba, MG 38304-402, Brazil
| | - Paula de Souza Santos
- Institute of Genetics and Biochemistry, Federal University of Uberlândia, Campus Umuarama, Uberlândia, MG 38400-902, Brazil
| | - Luiz Ricardo Goulart
- Institute of Genetics and Biochemistry, Federal University of Uberlândia, Campus Umuarama, Uberlândia, MG 38400-902, Brazil
| | - Foued Salmen Espindola
- Institute of Genetics and Biochemistry, Federal University of Uberlândia, Campus Umuarama, Uberlândia, MG 38400-902, Brazil.
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15
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Stall R, Ramos J, Kent Fulcher F, Patel YM. Regulation of myosin IIA and filamentous actin during insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Exp Cell Res 2013; 322:81-8. [PMID: 24374234 DOI: 10.1016/j.yexcr.2013.12.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/04/2013] [Accepted: 12/08/2013] [Indexed: 11/18/2022]
Abstract
Insulin stimulated glucose uptake requires the colocalization of myosin IIA (MyoIIA) and the insulin-responsive glucose transporter 4 (GLUT4) at the plasma membrane for proper GLUT4 fusion. MyoIIA facilitates filamentous actin (F-actin) reorganization in various cell types. In adipocytes F-actin reorganization is required for insulin-stimulated glucose uptake. What is not known is whether MyoIIA interacts with F-actin to regulate insulin-induced GLUT4 fusion at the plasma membrane. To elucidate the relationship between MyoIIA and F-actin, we examined the colocalization of MyoIIA and F-actin at the plasma membrane upon insulin stimulation as well as the regulation of this interaction. Our findings demonstrated that MyoIIA and F-actin colocalized at the site of GLUT4 fusion with the plasma membrane upon insulin stimulation. Furthermore, inhibition of MyoII with blebbistatin impaired F-actin localization at the plasma membrane. Next we examined the regulatory role of calcium in MyoIIA-F-actin colocalization. Reduced calcium or calmodulin levels decreased colocalization of MyoIIA and F-actin at the plasma membrane. While calcium alone can translocate MyoIIA it did not stimulate F-actin accumulation at the plasma membrane. Taken together, we established that while MyoIIA activity is required for F-actin localization at the plasma membrane, it alone is insufficient to localize F-actin to the plasma membrane.
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Affiliation(s)
- Richard Stall
- Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA
| | - Joseph Ramos
- Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA
| | - F Kent Fulcher
- Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA
| | - Yashomati M Patel
- Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA.
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16
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Woody S, Stall R, Ramos J, Patel YM. Regulation of myosin light chain kinase during insulin-stimulated glucose uptake in 3T3-L1 adipocytes. PLoS One 2013; 8:e77248. [PMID: 24116218 PMCID: PMC3792908 DOI: 10.1371/journal.pone.0077248] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/09/2013] [Indexed: 11/25/2022] Open
Abstract
Myosin II (MyoII) is required for insulin-responsive glucose transporter 4 (GLUT4)-mediated glucose uptake in 3T3-L1 adipocytes. Our previous studies have shown that insulin signaling stimulates phosphorylation of the regulatory light chain (RLC) of MyoIIA via myosin light chain kinase (MLCK). The experiments described here delineate upstream regulators of MLCK during insulin-stimulated glucose uptake. Since 3T3-L1 adipocytes express two MyoII isoforms, we wanted to determine which isoform was required for insulin-stimulated glucose uptake. Using a siRNA approach, we demonstrate that a 60% decrease in MyoIIA protein expression resulted in a 40% inhibition of insulin-stimulated glucose uptake. We also show that insulin signaling stimulates the phosphorylation of MLCK. We further show that MLCK can be activated by calcium as well as signaling pathways. We demonstrate that adipocytes treated with the calcium chelating agent, 1,2-b (iso-aminophenoxy) ethane-N,N,N',N'-tetra acetic acid, (BAPTA) (in the presence of insulin) impaired the insulin-induced phosphorylation of MLCK by 52% and the RLC of MyoIIA by 45% as well as impairing the recruitment of MyoIIA to the plasma membrane when compared to cells treated with insulin alone. We further show that the calcium ionophore, A23187 alone stimulated the phosphorylation of MLCK and the RLC associated with MyoIIA to the same extent as insulin. To identify signaling pathways that might regulate MLCK, we examined ERK and CaMKII. Inhibition of ERK2 impaired phosphorylation of MLCK and insulin-stimulated glucose uptake. In contrast, while inhibition of CaMKII did inhibit phosphorylation of the RLC associated with MyoIIA, inhibition of CAMKIIδ did not impair MLCK phosphorylation or translocation to the plasma membrane or glucose uptake. Collectively, our results are the first to delineate a role for calcium and ERK in the activation of MLCK and thus MyoIIA during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.
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Affiliation(s)
- Shelly Woody
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Richard Stall
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Joseph Ramos
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Yashomati M. Patel
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
- * E-mail:
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Cholangiocyte myosin IIB is required for localized aggregation of sodium glucose cotransporter 1 to sites of Cryptosporidium parvum cellular invasion and facilitates parasite internalization. Infect Immun 2010; 78:2927-36. [PMID: 20457792 DOI: 10.1128/iai.00077-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Internalization of the obligate intracellular apicomplexan parasite, Cryptosporidium parvum, results in the formation of a unique intramembranous yet extracytoplasmic niche on the apical surfaces of host epithelial cells, a process that depends on host cell membrane extension. We previously demonstrated that efficient C. parvum invasion of biliary epithelial cells (cholangiocytes) requires host cell actin polymerization and localized membrane translocation/insertion of Na(+)/glucose cotransporter 1 (SGLT1) and of aquaporin 1 (Aqp1), a water channel, at the attachment site. The resultant localized water influx facilitates parasite cellular invasion by promoting host-cell membrane protrusion. However, the molecular mechanisms by which C. parvum induces membrane translocation/insertion of SGLT1/Aqp1 are obscure. We report here that cultured human cholangiocytes express several nonmuscle myosins, including myosins IIA and IIB. Moreover, C. parvum infection of cultured cholangiocytes results in the localized selective aggregation of myosin IIB but not myosin IIA at the region of parasite attachment, as assessed by dual-label immunofluorescence confocal microscopy. Concordantly, treatment of cells with the myosin light chain kinase inhibitor ML-7 or the myosin II-specific inhibitor blebbistatin or selective RNA-mediated repression of myosin IIB significantly inhibits (P < 0.05) C. parvum cellular invasion (by 60 to 80%). Furthermore ML-7 and blebbistatin significantly decrease (P < 0.02) C. parvum-induced accumulation of SGLT1 at infection sites (by approximately 80%). Thus, localized actomyosin-dependent membrane translocation of transporters/channels initiated by C. parvum is essential for membrane extension and parasite internalization, a phenomenon that may also be relevant to the mechanisms of cell membrane protrusion in general.
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Ahmed M, Neville MJ, Edelmann MJ, Kessler BM, Karpe F. Proteomic analysis of human adipose tissue after rosiglitazone treatment shows coordinated changes to promote glucose uptake. Obesity (Silver Spring) 2010; 18:27-34. [PMID: 19556978 DOI: 10.1038/oby.2009.208] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The aim of this study was to identify potential protein targets for insulin sensitization in human adipose tissue using unbiased proteomic approaches. Ten moderately obese, but otherwise healthy, subjects were treated with rosiglitazone 4 mg b.i.d. for 14 days and global protein and gene expression changes were monitored. Proteomic analysis revealed distinct up- or downregulation (greater than twofold) in 187 protein spots on the two-dimensional (2-D) gel images between day 0 and day 1 adipose tissue samples. When comparing the protein spots on the gels from day 0 with that of 14-day-treated samples, 122 spots showed differential expression. There was a striking increase in the expression of proteins involved in glucose transporter-4 (GLUT4) granule transport and fusion (actin, myosin-9, tubulin, vimentin, annexins, moesin, LIM, and SH3 domain protein-1), signaling (calmodulin, guanine nucleotide-binding proteins), redox regulation (superoxide dismutase, catalase, ferritin, transferrin, heat shock proteins), and adipogenesis (collagens, galectin-1, nidogen-1, laminin, lamin A/C). However, there was an intriguing absence of correlated changes in mRNA expression, suggesting adaptation at a post-transcriptional level in response to rosiglitazone. Thus, the major changes observed were among proteins involved in cytoskeletal rearrangement, insulin and calcium signaling, and inflammatory and redox signals that decisively upregulate GLUT4 granule trafficking in human adipose tissue. Such orchestrated changes in expression of multiple proteins provide insights into the mechanism underlying the increased efficiency in glucose uptake and improvement of insulin sensitivity in response to rosiglitazone treatment.
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Affiliation(s)
- Meftun Ahmed
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
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19
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Myosin IIA participates in docking of Glut4 storage vesicles with the plasma membrane in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2009; 391:995-9. [PMID: 19968963 DOI: 10.1016/j.bbrc.2009.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 12/02/2009] [Indexed: 01/27/2023]
Abstract
In adipocytes and myocytes, insulin stimulation translocates glucose transporter 4 (Glut4) storage vesicles (GSVs) from their intracellular storage sites to the plasma membrane (PM) where they dock with the PM. Then, Glut4 is inserted into the PM and initiates glucose uptake into these cells. Previous studies using chemical inhibitors demonstrated that myosin II participates in fusion of GSVs and the PM and increase in the intrinsic activity of Glut4. In this study, the effect of myosin IIA on GSV trafficking was examined by knocking down myosin IIA expression. Myosin IIA knockdown decreased both glucose uptake and exposures of myc-tagged Glut4 to the cell surface in insulin-stimulated cells, but did not affect insulin signal transduction. Interestingly, myosin IIA knockdown failed to decrease insulin-dependent trafficking of Glut4 to the PM. Moreover, in myosin IIA knockdown cells, insulin-stimulated binding of GSV SNARE protein, vesicle-associated membrane protein 2 (VAMP2) to PM SNARE protein, syntaxin 4 was inhibited. These data suggest that myosin IIA plays a role in insulin-stimulated docking of GSVs to the PM in 3T3-L1 adipocytes through SNARE complex formation.
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20
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Megalin and nonmuscle myosin heavy chain IIA interact with the adaptor protein Disabled-2 in proximal tubule cells. Kidney Int 2009; 75:1308-1315. [PMID: 19340093 DOI: 10.1038/ki.2009.85] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Megalin plays a critical role in the endocytosis of albumin and other filtered low-molecular-weight proteins. Here we studied the interaction between megalin and Disabled-2 (Dab2), an adaptor protein that binds to the cytoplasmic domain of megalin and appears to control its trafficking. We co-immunoprecipitated megalin and Dab2 from cultured proximal tubule cells and identified the proteins by liquid chromatography and tandem mass spectrometry. We found two proteins associated with the megalin/Dab2 complex, nonmuscle myosin heavy chain IIA (NMHC-IIA) and beta-actin. Subcellular fractionation followed by sucrose velocity gradient separation showed that megalin, Dab2, and NMHC-IIA existed as a complex in the same endosomal fractions. In vitro pull-down assays demonstrated that NMHC-IIA was bound to the carboxyl-terminal region of Dab2, but not to megalin's cytoplasmic domain. We then transfected COS-7 cells with plasmids that induced the expression of Dab2, NMHC-IIA, and the megalin minireceptor, a truncated form of megalin. Co-immunoprecipitation studies showed that the minireceptor and NMHC-IIA co-immunoprecipitated only with Dab2. Furthermore, the uptake of (125)I-lactoferrin, an endocytic ligand of megalin, by rat yolk sac-derived megalin-expressing L2 cells was inhibited by blebbistatin, a specific inhibitor of nonmuscle myosin II. Our study shows that NMHC-IIA is functionally linked to megalin by interaction with Dab2 and is likely involved in megalin-mediated endocytosis in proximal tubule cells.
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21
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Duan R, Gallagher PJ. Dependence of myoblast fusion on a cortical actin wall and nonmuscle myosin IIA. Dev Biol 2008; 325:374-85. [PMID: 19027000 DOI: 10.1016/j.ydbio.2008.10.035] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 10/23/2008] [Accepted: 10/27/2008] [Indexed: 01/22/2023]
Abstract
Cell-cell fusion is a fundamental cellular process that is essential for development as well as fertilization. Myoblast fusion to form multinucleated skeletal muscle myotubes is a well studied, yet incompletely understood example of cell-cell fusion that is essential for formation of contractile skeletal muscle tissue. Studies in this report identify several novel cytoskeletal events essential to an early phase of myoblast fusion among cultured murine myoblasts. During myoblast pairing and alignment, cortical actin filaments organize into a dense actin wall structure that parallels and extends the length of the plasma membrane of the bipolar, aligned cells. As fusion progresses, gaps appear within the actin wall at sites of vesicle accumulation, the vesicles pair across the aligned myoblasts, cell-cell contacts and fusion pores form. Inhibition of nonmuscle myosin IIA (NM-MHC-IIA) motor activity prevents formation of this cortical actin wall, as well as the appearance of vesicles at a membrane proximal location, and myoblast fusion. These results suggest that early formation of a subplasmalemmal actin wall during myoblast alignment is a critical event for myoblast fusion that supports bipolar membrane alignment and temporally regulates trafficking of vesicles to the nascent fusion sites during skeletal muscle myoblast differentiation.
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Affiliation(s)
- Rui Duan
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202-5120, USA
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22
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Dual role for myosin II in GLUT4-mediated glucose uptake in 3T3-L1 adipocytes. Exp Cell Res 2008; 314:3264-74. [PMID: 18773891 DOI: 10.1016/j.yexcr.2008.08.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 08/07/2008] [Accepted: 08/10/2008] [Indexed: 01/15/2023]
Abstract
Insulin-stimulated glucose uptake requires the activation of several signaling pathways to mediate the translocation and fusion of GLUT4 vesicles to the plasma membrane. Our previous studies demonstrated that GLUT4-mediated glucose uptake is a myosin II-dependent process in adipocytes. The experiments described in this report are the first to show a dual role for the myosin IIA isoform specifically in regulating insulin-stimulated glucose uptake in adipocytes. We demonstrate that inhibition of MLCK but not RhoK results in impaired insulin-stimulated glucose uptake. Furthermore, our studies show that insulin specifically stimulates the phosphorylation of the RLC associated with the myosin IIA isoform via MLCK. In time course experiments, we determined that GLUT4 translocates to the plasma membrane prior to myosin IIA recruitment. We further show that recruitment of myosin IIA to the plasma membrane requires that myosin IIA be activated via phosphorylation of the RLC by MLCK. Our findings also reveal that myosin II is required for proper GLUT4-vesicle fusion at the plasma membrane. We show that once at the plasma membrane, myosin II is involved in regulating the intrinsic activity of GLUT4 after insulin stimulation. Collectively, our results are the first to reveal that myosin IIA plays a critical role in mediating insulin-stimulated glucose uptake in 3T3-LI adipocytes, via both GLUT4 vesicle fusion at the plasma membrane and GLUT4 activity.
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23
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Dou Y, Arlock P, Arner A. Blebbistatin specifically inhibits actin-myosin interaction in mouse cardiac muscle. Am J Physiol Cell Physiol 2007; 293:C1148-53. [PMID: 17615158 DOI: 10.1152/ajpcell.00551.2006] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Blebbistatin is a powerful inhibitor of actin-myosin interaction in isolated contractile proteins. To examine whether blebbistatin acts in a similar manner in the organized contractile system of striated muscle, the effects of blebbistatin on contraction of cardiac tissue from mouse were studied. The contraction of paced intact papillary muscle preparations and shortening of isolated cardiomyocytes were inhibited by blebbistatin with inhibitory constants in the micromolar range (1.3-2.8 muM). The inhibition constants are similar to those previously reported for isolated cardiac myosin subfragments showing that blebbistatin action is similar in filamentous myosin of the cardiac contractile apparatus and isolated proteins. The inhibition was not associated with alterations in action potential duration or decreased influx through L-type Ca(2+) channels. Experiments on permeabilized cardiac muscle preparations showed that the inhibition was not due to alterations in Ca(2+) sensitivity of the contractile filaments. The maximal shortening velocity was not affected by 1 muM blebbistatin. In conclusion, we show that blebbistatin is an inhibitor of the actin-myosin interaction in the organized contractile system of cardiac muscle and that its action is not due to effects on the Ca(2+) influx and activation systems.
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Affiliation(s)
- Ying Dou
- Dept. of Physiology and Pharmacology, Karolinska Institutet, SE 171 77 Stockholm, Sweden
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24
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Funaki M, DiFransico L, Janmey PA. PI 4,5-P2 stimulates glucose transport activity of GLUT4 in the plasma membrane of 3T3-L1 adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:889-99. [PMID: 16828894 PMCID: PMC3118463 DOI: 10.1016/j.bbamcr.2006.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/08/2006] [Accepted: 05/09/2006] [Indexed: 12/16/2022]
Abstract
Insulin-stimulated glucose uptake through GLUT4 plays a pivotal role in maintaining normal blood glucose levels. Glucose transport through GLUT4 requires both GLUT4 translocation to the plasma membrane and GLUT4 activation at the plasma membrane. Here we report that a cell-permeable phosphoinositide-binding peptide, which induces GLUT4 translocation without activation, sequestered PI 4,5-P2 in the plasma membrane from its binding partners. Restoring PI 4,5-P2 to the plasma membrane after the peptide treatment increased glucose uptake. No additional glucose transporters were recruited to the plasma membrane, suggesting that the increased glucose uptake was attributable to GLUT4 activation. Cells overexpressing phosphatidylinositol-4-phosphate 5-kinase treated with the peptide followed by its removal exhibited a higher level of glucose transport than cells stimulated with a submaximal level of insulin. However, only cells treated with submaximal insulin exhibited translocation of the PH-domains of the general receptor for phosphoinositides (GRP1) to the plasma membrane. Thus, PI 4,5-P2, but not PI 3,4,5-P3 converted from PI 4,5-P2, induced GLUT4 activation. Inhibiting F-actin remodeling after the peptide treatment significantly impaired GLUT4 activation induced either by PI 4,5-P2 or by insulin. These results suggest that PI 4,5-P2 in the plasma membrane acts as a second messenger to activate GLUT4, possibly through F-actin remodeling.
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Affiliation(s)
- Makoto Funaki
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, 1080 Vagelos Research Laboratories, 3340 Smith Walk, Philadelphia, 19104, USA.
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Russ M, Croft D, Ali O, Martinez R, Steimle P. Myosin heavy-chain kinase A from Dictyostelium possesses a novel actin-binding domain that cross-links actin filaments. Biochem J 2006; 395:373-83. [PMID: 16372899 PMCID: PMC1422765 DOI: 10.1042/bj20051376] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Myosin heavy-chain kinase A (MHCK A) catalyses the disassembly of myosin II filaments in Dictyostelium cells via myosin II heavy-chain phosphorylation. MHCK A possesses a 'coiled-coil'-enriched domain that mediates the oligomerization, cellular localization and actin-binding activities of the kinase. F-actin (filamentous actin) binding by the coiled-coil domain leads to a 40-fold increase in MHCK A activity. In the present study we examined the actin-binding characteristics of the coiled-coil domain as a means of identifying mechanisms by which MHCK A-mediated disassembly of myosin II filaments can be regulated in the cell. Co-sedimentation assays revealed that the coiled-coil domain of MHCK A binds co-operatively to F-actin with an apparent K(D) of approx. 0.5 muM and a stoichiometry of approx. 5:1 [actin/C(1-498)]. Further analyses indicate that the coiled-coil domain binds along the length of the actin filament and possesses at least two actin-binding regions. Quite surprisingly, we found that the coiled-coil domain cross-links actin filaments into bundles, indicating that MHCK A can affect the cytoskeleton in two important ways: (1) by driving myosin II-filament disassembly via myosin II heavy-chain phosphorylation, and (2) by cross-linking/bundling actin filaments. This discovery, along with other supporting data, suggests a model in which MHCK A-mediated bundling of actin filaments plays a central role in the recruitment and activation of the kinase at specific sites in the cell. Ultimately this provides a means for achieving the robust and highly localized disruption of myosin II filaments that facilitates polarized changes in cell shape during processes such as chemotaxis, cytokinesis and multicellular development.
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Affiliation(s)
- Misty Russ
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, U.S.A
| | - Daniel Croft
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, U.S.A
| | - Omar Ali
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, U.S.A
| | - Raquel Martinez
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, U.S.A
| | - Paul A. Steimle
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, U.S.A
- To whom correspondence should be addressed (email )
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