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Liu PJ, Sayeeda K, Zhuang C, Krendel M. Roles of myosin 1e and the actin cytoskeleton in kidney functions and familial kidney disease. Cytoskeleton (Hoboken) 2024. [PMID: 38708443 DOI: 10.1002/cm.21861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 03/21/2024] [Accepted: 04/04/2024] [Indexed: 05/07/2024]
Abstract
Mammalian kidneys are responsible for removing metabolic waste and maintaining fluid and electrolyte homeostasis via selective filtration. One of the proteins closely linked to selective renal filtration is myosin 1e (Myo1e), an actin-dependent molecular motor found in the specialized kidney epithelial cells involved in the assembly and maintenance of the renal filter. Point mutations in the gene encoding Myo1e, MYO1E, have been linked to familial kidney disease, and Myo1e knockout in mice leads to the disruption of selective filtration. In this review, we discuss the role of the actin cytoskeleton in renal filtration, the known and hypothesized functions of Myo1e, and the possible explanations for the impact of MYO1E mutations on renal function.
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Affiliation(s)
- Pei-Ju Liu
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Kazi Sayeeda
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Cindy Zhuang
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA
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2
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Zanni-Ruiz E, Mayorga L, Pavarotti M. Flow cytometry protocol for GLUT4-myc detection on cell surfaces. Biosci Rep 2024; 44:BSR20231987. [PMID: 38533799 PMCID: PMC11016532 DOI: 10.1042/bsr20231987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/05/2024] [Accepted: 03/26/2024] [Indexed: 03/28/2024] Open
Abstract
Insulin and muscle contraction trigger GLUT4 translocation to the plasma membrane, which increases glucose uptake by muscle cells. Insulin resistance and Type 2 diabetes are the result of impaired GLUT4 translocation. Quantifying GLUT4 translocation is essential for comprehending the intricacies of both physiological and pathophysiological processes involved in glucose metabolism. The most commonly used methods for measuring GLUT4 translocation are the ELISA-type assay and the immunofluorescence assay. While some reports suggest that flow cytometry could be useful in quantifying GLUT4 translocation, this technique is not frequently used. Much of our current understanding of the regulation of GLUT4 has been based on experiments using the rat myoblast cell line (L6 cell) which expresses GLUT4 with a myc epitope on the exofacial loop. In the present study, we use the L6-GLUT4myc cell line to develop a flow cytometry-based approach to detect GLUT4 translocation. Flow cytometry offers the advantages of both immunofluorescence and ELISA-based assays. It allows easy identification of separate cell populations in the sample, similar to immunofluorescence, while providing results based on a population-level analysis of multiple individual cells, like an ELISA-based assay. Our results demonstrate a 0.6-fold increase with insulin stimulation compared with basal conditions. Finally, flow cytometry consistently yielded results across different experiments and exhibited sensitivity under the tested conditions.
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Affiliation(s)
- Emilia Zanni-Ruiz
- Laboratorio de Transporte Intracelular, Instituto de Histología y Embriología de Mendoza Dr. Mario H Burgos, Mendoza, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Luis Segundo Mayorga
- Laboratorio de Transporte Intracelular, Instituto de Histología y Embriología de Mendoza Dr. Mario H Burgos, Mendoza, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
- Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Martin Alejandro Pavarotti
- Laboratorio de Transporte Intracelular, Instituto de Histología y Embriología de Mendoza Dr. Mario H Burgos, Mendoza, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- Universidad Nacional de Cuyo, Mendoza, Argentina
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3
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Sato Y, Yoshimura K, Matsuda K, Haraguchi T, Marumo A, Yamagishi M, Sato S, Ito K, Yajima J. Membrane-bound myosin IC drives the chiral rotation of the gliding actin filament around its longitudinal axis. Sci Rep 2023; 13:19908. [PMID: 37963943 PMCID: PMC10646037 DOI: 10.1038/s41598-023-47125-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/09/2023] [Indexed: 11/16/2023] Open
Abstract
Myosin IC, a single-headed member of the myosin I family, specifically interacts with anionic phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) in the cell membrane via the pleckstrin homology domain located in the myosin IC tail. Myosin IC is widely expressed and physically links the cell membrane to the actin cytoskeleton; it plays various roles in membrane-associated physiological processes, including establishing cellular chirality, lipid transportation, and mechanosensing. In this study, we evaluated the motility of full-length myosin IC of Drosophila melanogaster via the three-dimensional tracking of quantum dots bound to actin filaments that glided over a membrane-bound myosin IC-coated surface. The results revealed that myosin IC drove a left-handed rotational motion in the gliding actin filament around its longitudinal axis, indicating that myosin IC generated a torque perpendicular to the gliding direction of the actin filament. The quantification of the rotational motion of actin filaments on fluid membranes containing different PI(4,5)P2 concentrations revealed that the rotational pitch was longer at lower PI(4,5)P2 concentrations. These results suggest that the torque generated by membrane-bound myosin IC molecules can be modulated based on the phospholipid composition of the cell membrane.
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Affiliation(s)
- Yusei Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Kohei Yoshimura
- Department of Biology, Graduate School of Science, Chiba University, 1-33, Inage, Chiba, Japan
| | - Kyohei Matsuda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Takeshi Haraguchi
- Department of Biology, Graduate School of Science, Chiba University, 1-33, Inage, Chiba, Japan
| | - Akisato Marumo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Suguru Sato
- Department of Biology, Graduate School of Science, Chiba University, 1-33, Inage, Chiba, Japan
| | - Kohji Ito
- Department of Biology, Graduate School of Science, Chiba University, 1-33, Inage, Chiba, Japan.
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
- Komaba Institute for Science, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
- Research Center for Complex Systems Biology, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
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4
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Venit T, Sapkota O, Abdrabou WS, Loganathan P, Pasricha R, Mahmood SR, El Said NH, Sherif S, Thomas S, Abdelrazig S, Amin S, Bedognetti D, Idaghdour Y, Magzoub M, Percipalle P. Positive regulation of oxidative phosphorylation by nuclear myosin 1 protects cells from metabolic reprogramming and tumorigenesis in mice. Nat Commun 2023; 14:6328. [PMID: 37816864 PMCID: PMC10564744 DOI: 10.1038/s41467-023-42093-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/29/2023] [Indexed: 10/12/2023] Open
Abstract
Metabolic reprogramming is one of the hallmarks of tumorigenesis. Here, we show that nuclear myosin 1 (NM1) serves as a key regulator of cellular metabolism. NM1 directly affects mitochondrial oxidative phosphorylation (OXPHOS) by regulating mitochondrial transcription factors TFAM and PGC1α, and its deletion leads to underdeveloped mitochondria inner cristae and mitochondrial redistribution within the cell. These changes are associated with reduced OXPHOS gene expression, decreased mitochondrial DNA copy number, and deregulated mitochondrial dynamics, which lead to metabolic reprogramming of NM1 KO cells from OXPHOS to aerobic glycolysis.This, in turn, is associated with a metabolomic profile typical for cancer cells, namely increased amino acid-, fatty acid-, and sugar metabolism, and increased glucose uptake, lactate production, and intracellular acidity. NM1 KO cells form solid tumors in a mouse model, suggesting that the metabolic switch towards aerobic glycolysis provides a sufficient carcinogenic signal. We suggest that NM1 plays a role as a tumor suppressor and that NM1 depletion may contribute to the Warburg effect at the onset of tumorigenesis.
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Affiliation(s)
- Tomas Venit
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Oscar Sapkota
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Wael Said Abdrabou
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
- Center for Genomics and Systems Biology, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Palanikumar Loganathan
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Renu Pasricha
- Core Technology Platforms, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Syed Raza Mahmood
- Center for Genomics and Systems Biology, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Nadine Hosny El Said
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Shimaa Sherif
- Translational Medicine Department, Research Branch, Sidra Medicine, Doha, Qatar
| | - Sneha Thomas
- Core Technology Platforms, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Salah Abdelrazig
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Shady Amin
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Davide Bedognetti
- Translational Medicine Department, Research Branch, Sidra Medicine, Doha, Qatar
- Department of Internal Medicine and Medical Specialties (DiMI), University of Genoa, Genoa, Italy
- College of Health and Life Sciences, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar
| | - Youssef Idaghdour
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
- Center for Genomics and Systems Biology, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Mazin Magzoub
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates
| | - Piergiorgio Percipalle
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates.
- Center for Genomics and Systems Biology, New York University Abu Dhabi (NYUAD), P.O. Box, 129188, Abu Dhabi, United Arab Emirates.
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden.
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SMOC2 promotes aggressive behavior of fibroblast-like synoviocytes in rheumatoid arthritis through transcriptional and post-transcriptional regulating MYO1C. Cell Death Dis 2022; 13:1035. [PMID: 36513634 PMCID: PMC9747908 DOI: 10.1038/s41419-022-05479-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022]
Abstract
Fibroblast-like synoviocytes (FLSs), play a key role in perpetuating synovial inflammation and bone erosion in rheumatoid arthritis (RA), however, the underlying mechanism(s) of RA FLSs activation and aggression remain unclear. Identifying endogenous proteins that selectively target FLSs is urgently needed. Here, we systematically identified that secreted modular calcium-binding protein 2 (SMOC2), was significantly increased in RA FLSs and synovial tissues. SMOC2 knockdown specifically regulated cytoskeleton remodeling and decreased the migration and invasion of RA FLSs. Mechanistically, cytoskeleton-related genes were significantly downregulated in RA FLSs with reduced SMOC2 expression, especially the motor protein myosin1c (MYO1C). SMOC2 controlled MYO1C expression by SRY-related high-mobility group box 4 (SOX4) and AlkB homolog 5 (ALKHB5) mediated-m6A modification through transcriptional and post-transcriptional regulation. Furthermore, intra-articular Ad-shRNA-SMOC2 treatment attenuated synovial inflammation as well as bone and cartilage erosion in rats with collagen-induced arthritis (CIA). Our findings suggest that increased SMOC2 expression in FLSs may contribute to synovial aggression and joint destruction in RA. SMOC2 may serve as a potential target against RA. SMOC2-mediated regulation of the synovial migration and invasion in RA FLSs. In RA FLSs, SMOC2 is significantly increased, leading to the increased level of MYO1C via SOX4-mediated transcriptional regulation and ALKBH5-mediated m6A modification, thereby causing cytoskeleton remodeling and promoting RA FLSs migration and invasion. The Figure was drawn by Figdraw.
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Pernier J, Schauer K. Does the Actin Network Architecture Leverage Myosin-I Functions? BIOLOGY 2022; 11:biology11070989. [PMID: 36101369 PMCID: PMC9311500 DOI: 10.3390/biology11070989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/24/2022] [Accepted: 06/26/2022] [Indexed: 11/16/2022]
Abstract
The actin cytoskeleton plays crucial roles in cell morphogenesis and functions. The main partners of cortical actin are molecular motors of the myosin superfamily. Although our understanding of myosin functions is heavily based on myosin-II and its ability to dimerize, the largest and most ancient class is represented by myosin-I. Class 1 myosins are monomeric, actin-based motors that regulate a wide spectrum of functions, and whose dysregulation mediates multiple human diseases. We highlight the current challenges in identifying the “pantograph” for myosin-I motors: we need to reveal how conformational changes of myosin-I motors lead to diverse cellular as well as multicellular phenotypes. We review several mechanisms for scaling, and focus on the (re-) emerging function of class 1 myosins to remodel the actin network architecture, a higher-order dynamic scaffold that has potential to leverage molecular myosin-I functions. Undoubtfully, understanding the molecular functions of myosin-I motors will reveal unexpected stories about its big partner, the dynamic actin cytoskeleton.
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Affiliation(s)
- Julien Pernier
- Institute for Integrative Biology of the Cell (I2BC), Centre National de la Recherche Scientifique (CNRS), Commissariat à L’Énergie Atomique et aux Énergies Alternatives (CEA), Université Paris-Saclay, 91198 Gif-sur-Yvette, France;
| | - Kristine Schauer
- Tumor Cell Dynamics Unit, Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, 94800 Villejuif, France
- Correspondence:
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7
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Reindl T, Giese S, Greve JN, Reinke PY, Chizhov I, Latham SL, Mulvihill DP, Taft MH, Manstein DJ. Distinct actin–tropomyosin cofilament populations drive the functional diversification of cytoskeletal myosin motor complexes. iScience 2022; 25:104484. [PMID: 35720262 PMCID: PMC9204724 DOI: 10.1016/j.isci.2022.104484] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 05/02/2022] [Accepted: 05/24/2022] [Indexed: 11/02/2022] Open
Abstract
The effects of N-terminal acetylation of the high molecular weight tropomyosin isoforms Tpm1.6 and Tpm2.1 and the low molecular weight isoforms Tpm1.12, Tpm3.1, and Tpm4.2 on the actin affinity and the thermal stability of actin-tropomyosin cofilaments are described. Furthermore, we show how the exchange of cytoskeletal tropomyosin isoforms and their N-terminal acetylation affects the kinetic and chemomechanical properties of cytoskeletal actin-tropomyosin-myosin complexes. Our results reveal the extent to which the different actin-tropomyosin-myosin complexes differ in their kinetic and functional properties. The maximum sliding velocity of the actin filament as well as the optimal motor density for continuous unidirectional movement, parameters that were previously considered to be unique and invariant properties of each myosin isoform, are shown to be influenced by the exchange of the tropomyosin isoform and the N-terminal acetylation of tropomyosin. Tpm diversity is largely determined by sequences contributing to the overlap region Global sequence differences are of greater importance than variable exon 6 usage Tpm isoforms confer distinctly altered properties to cytoskeletal myosin motors Cytoskeletal myosins are differentially affected by N-terminal acetylation of Tpm
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8
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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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Fazakerley DJ, Koumanov F, Holman GD. GLUT4 On the move. Biochem J 2022; 479:445-462. [PMID: 35147164 PMCID: PMC8883492 DOI: 10.1042/bcj20210073] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 01/11/2022] [Accepted: 01/14/2022] [Indexed: 12/16/2022]
Abstract
Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream signalling changes in serine/threonine kinases within timescales of seconds, and this is followed by delivery and accumulation of the glucose transporter GLUT4 at the plasma membrane. Kinetic studies have led to realisation that there are distinct phases of this stimulation by insulin. There is a rapid initial burst of GLUT4 delivered to the cell surface from a subcellular reservoir compartment and this is followed by a steady-state level of continuing stimulation in which GLUT4 recycles through a large itinerary of subcellular locations. Here, we provide an overview of the phases of insulin stimulation of GLUT4 translocation and the molecules that are currently considered to activate these trafficking steps. Furthermore, we suggest how use of new experimental approaches together with phospho-proteomic data may help to further identify mechanisms for activation of these trafficking processes.
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Affiliation(s)
- Daniel J Fazakerley
- Metabolic Research Laboratories, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, U.K
| | - Francoise Koumanov
- Department for Health, Centre for Nutrition, Exercise, and Metabolism, University of Bath, Bath, Somerset BA2 7AY, U.K
| | - Geoffrey D Holman
- Department of Biology and Biochemistry, University of Bath, Bath, Somerset BA2 7AY, U.K
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Solanki AK, Biswal MR, Walterhouse S, Martin R, Kondkar AA, Knölker HJ, Rahman B, Arif E, Husain S, Montezuma SR, Nihalani D, Lobo GP. Loss of Motor Protein MYO1C Causes Rhodopsin Mislocalization and Results in Impaired Visual Function. Cells 2021; 10:cells10061322. [PMID: 34073294 PMCID: PMC8229726 DOI: 10.3390/cells10061322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/12/2022] Open
Abstract
Unconventional myosins, linked to deafness, are also proposed to play a role in retinal cell physiology. However, their direct role in photoreceptor function remains unclear. We demonstrate that systemic loss of the unconventional myosin MYO1C in mice, specifically causes rhodopsin mislocalization, leading to impaired visual function. Electroretinogram analysis of Myo1c knockout (Myo1c-KO) mice showed a progressive loss of photoreceptor function. Immunohistochemistry and binding assays demonstrated MYO1C localization to photoreceptor inner and outer segments (OS) and identified a direct interaction of rhodopsin with MYO1C. In Myo1c-KO retinas, rhodopsin mislocalized to rod inner segments (IS) and cell bodies, while cone opsins in OS showed punctate staining. In aged mice, the histological and ultrastructural examination of the phenotype of Myo1c-KO retinas showed progressively shorter photoreceptor OS. These results demonstrate that MYO1C is important for rhodopsin localization to the photoreceptor OS, and for normal visual function.
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Affiliation(s)
- Ashish K. Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (S.W.); (B.R.); (E.A.)
| | - Manas R. Biswal
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL 33612, USA;
| | - Stephen Walterhouse
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (S.W.); (B.R.); (E.A.)
| | - René Martin
- Faculty of Chemistry, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany; (R.M.); (H.-J.K.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia;
| | - Hans-Joachim Knölker
- Faculty of Chemistry, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany; (R.M.); (H.-J.K.)
| | - Bushra Rahman
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (S.W.); (B.R.); (E.A.)
| | - Ehtesham Arif
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (S.W.); (B.R.); (E.A.)
| | - Shahid Husain
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, USA;
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, 516 Delaware Street S.E., 9th Floor, Minneapolis, MN 55455, USA;
| | - Deepak Nihalani
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bldg. 2DEM, Room 6085, 6707 Democracy Blvd., Bethesda, MD 20817, USA
- Correspondence: (D.N.); (G.P.L.)
| | - Glenn Prazere Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA; (A.K.S.); (S.W.); (B.R.); (E.A.)
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, USA;
- Department of Ophthalmology and Visual Neurosciences, Lions Research Building, University of Minnesota, 2001 6th Street S.E., Room 225, Minneapolis, MN 55455, USA
- Correspondence: (D.N.); (G.P.L.)
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11
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Åslund A, Bokhari MH, Wetterdal E, Martin R, Knölker HJ, Bengtsson T. Myosin 1c: A novel regulator of glucose uptake in brown adipocytes. Mol Metab 2021; 53:101247. [PMID: 33965643 PMCID: PMC8182130 DOI: 10.1016/j.molmet.2021.101247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/26/2021] [Accepted: 05/03/2021] [Indexed: 12/02/2022] Open
Abstract
Objective The potential of brown adipose tissue (BAT) to influence energy homeostasis in animals and humans is encouraging as this tissue can increase fatty acid and glucose utilization to produce heat through uncoupling protein 1 (UCP1), but the actual mechanism of how the cell regulates glucose uptake is not fully understood. Myosin 1c (Myo1c) is an unconventional motor protein involved in several cellular processes, including insulin-mediated glucose uptake via GLUT4 vesicle fusion in white adipocytes, but its role in glucose uptake in BAT has not previously been investigated. Methods Using the specific inhibitor pentachloropseudilin (PClP), a neutralizing antibody assay, and siRNA, we examined the role of Myo1c in mechanisms leading to glucose uptake both in vitro in isolated mouse primary adipocytes and in vivo in mice. Results Our results show that inhibition of Myo1c removes insulin-stimulated glucose uptake in white adipocytes, while inducing glucose uptake in brown adipocytes, independent of GLUT4, by increasing the expression, translation, and translocation of GLUT1 to the plasma membrane. Inhibition of Myo1c leads to the activation of PKA and downstream substrates p38 and ATF-2, which are known to be involved in the expression of β-adrenergic genes. Conclusions Myo1c is a PKA repressor and regulates glucose uptake into BAT. Myo1c is a BAT-specific regulator of glucose uptake. Myo1c inhibition leads to increased expression, translation, and translocation of GLUT1. Myo1c inhibition results in increased activation of PKA and its downstream targets.
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Affiliation(s)
- Alice Åslund
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Muhammad Hamza Bokhari
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Erika Wetterdal
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - René Martin
- Faculty of Chemistry, Technical University of Dresden, Bergstrasse 66, 01069, Dresden, Germany
| | - Hans-Joachim Knölker
- Faculty of Chemistry, Technical University of Dresden, Bergstrasse 66, 01069, Dresden, Germany
| | - Tore Bengtsson
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden.
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12
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Abstract
As the principal tissue for insulin-stimulated glucose disposal, skeletal muscle is a primary driver of whole-body glycemic control. Skeletal muscle also uniquely responds to muscle contraction or exercise with increased sensitivity to subsequent insulin stimulation. Insulin's dominating control of glucose metabolism is orchestrated by complex and highly regulated signaling cascades that elicit diverse and unique effects on skeletal muscle. We discuss the discoveries that have led to our current understanding of how insulin promotes glucose uptake in muscle. We also touch upon insulin access to muscle, and insulin signaling toward glycogen, lipid, and protein metabolism. We draw from human and rodent studies in vivo, isolated muscle preparations, and muscle cell cultures to home in on the molecular, biophysical, and structural elements mediating these responses. Finally, we offer some perspective on molecular defects that potentially underlie the failure of muscle to take up glucose efficiently during obesity and type 2 diabetes.
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13
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Complexin-2 redistributes to the membrane of muscle cells in response to insulin and contributes to GLUT4 translocation. Biochem J 2021; 478:407-422. [DOI: 10.1042/bcj20200542] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/11/2020] [Accepted: 01/04/2021] [Indexed: 11/17/2022]
Abstract
Insulin stimulates glucose uptake in muscle cells by rapidly redistributing vesicles containing GLUT4 glucose transporters from intracellular compartments to the plasma membrane (PM). GLUT4 vesicle fusion requires the formation of SNARE complexes between vesicular VAMP and PM syntaxin4 and SNAP23. SNARE accessory proteins usually regulate vesicle fusion processes. Complexins aide in neuro-secretory vesicle-membrane fusion by stabilizing trans-SNARE complexes but their participation in GLUT4 vesicle fusion is unknown. We report that complexin-2 is expressed and homogeneously distributed in L6 rat skeletal muscle cells. Upon insulin stimulation, a cohort of complexin-2 redistributes to the PM. Complexin-2 knockdown markedly inhibited GLUT4 translocation without affecting proximal insulin signalling of Akt/PKB phosphorylation and actin fiber remodelling. Similarly, complexin-2 overexpression decreased maximal GLUT4 translocation suggesting that the concentration of complexin-2 is finely tuned to vesicle fusion. These findings reveal an insulin-dependent regulation of GLUT4 insertion into the PM involving complexin-2.
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14
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Wang T, Wang J, Hu X, Huang XJ, Chen GX. Current understanding of glucose transporter 4 expression and functional mechanisms. World J Biol Chem 2020; 11:76-98. [PMID: 33274014 PMCID: PMC7672939 DOI: 10.4331/wjbc.v11.i3.76] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/22/2020] [Accepted: 09/22/2020] [Indexed: 02/05/2023] Open
Abstract
Glucose is used aerobically and anaerobically to generate energy for cells. Glucose transporters (GLUTs) are transmembrane proteins that transport glucose across the cell membrane. Insulin promotes glucose utilization in part through promoting glucose entry into the skeletal and adipose tissues. This has been thought to be achieved through insulin-induced GLUT4 translocation from intracellular compartments to the cell membrane, which increases the overall rate of glucose flux into a cell. The insulin-induced GLUT4 translocation has been investigated extensively. Recently, significant progress has been made in our understanding of GLUT4 expression and translocation. Here, we summarized the methods and reagents used to determine the expression levels of Slc2a4 mRNA and GLUT4 protein, and GLUT4 translocation in the skeletal muscle, adipose tissues, heart and brain. Overall, a variety of methods such real-time polymerase chain reaction, immunohistochemistry, fluorescence microscopy, fusion proteins, stable cell line and transgenic animals have been used to answer particular questions related to GLUT4 system and insulin action. It seems that insulin-induced GLUT4 translocation can be observed in the heart and brain in addition to the skeletal muscle and adipocytes. Hormones other than insulin can induce GLUT4 translocation. Clearly, more studies of GLUT4 are warranted in the future to advance of our understanding of glucose homeostasis.
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Affiliation(s)
- Tiannan Wang
- Department of Nutrition, The University of Tennessee, Knoxville, TN 37996, United States
| | - Jing Wang
- College of Pharmacy, South-Central University for Nationalities, Wuhan 430074, Hubei Province, China
| | - Xinge Hu
- Department of Nutrition, The University of Tennessee, Knoxville, TN 37996, United States
| | - Xian-Ju Huang
- College of Pharmacy, South-Central University for Nationalities, Wuhan 430074, Hubei Province, China
| | - Guo-Xun Chen
- Department of Nutrition, The University of Tennessee, Knoxville, TN 37996, United States
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15
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Abstract
Myosins constitute a superfamily of actin-based molecular motor proteins that mediates a variety of cellular activities including muscle contraction, cell migration, intracellular transport, the formation of membrane projections, cell adhesion, and cell signaling. The 12 myosin classes that are expressed in humans share sequence similarities especially in the N-terminal motor domain; however, their enzymatic activities, regulation, ability to dimerize, binding partners, and cellular functions differ. It is becoming increasingly apparent that defects in myosins are associated with diseases including cardiomyopathies, colitis, glomerulosclerosis, neurological defects, cancer, blindness, and deafness. Here, we review the current state of knowledge regarding myosins and disease.
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16
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Ji HH, Ostap EM. The regulatory protein 14-3-3β binds to the IQ motifs of myosin-IC independent of phosphorylation. J Biol Chem 2020; 295:3749-3756. [PMID: 31811090 PMCID: PMC7086031 DOI: 10.1074/jbc.ra119.011227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 11/21/2019] [Indexed: 12/30/2022] Open
Abstract
Myosin-IC (Myo1c) has been proposed to function in delivery of glucose transporter type 4 (GLUT4)-containing vesicles to the plasma membrane in response to insulin stimulation. Current evidence suggests that, upon insulin stimulation, Myo1c is phosphorylated at Ser701, leading to binding of the signaling protein 14-3-3β. Biochemical and functional details of the Myo1c-14-3-3β interaction have yet to be described. Using recombinantly expressed proteins and mass spectrometry-based analyses to monitor Myo1c phosphorylation, along with pulldown, fluorescence binding, and additional biochemical assays, we show here that 14-3-3β is a dimer and, consistent with previous work, that it binds to Myo1c in the presence of calcium. This interaction was associated with dissociation of calmodulin (CaM) from the IQ motif in Myo1c. Surprisingly, we found that 14-3-3β binds to Myo1c independent of Ser701 phosphorylation in vitro Additionally, in contrast to previous reports, we did not observe Myo1c Ser701 phosphorylation by Ca2+/CaM-dependent protein kinase II (CaMKII), although CaMKII phosphorylated four other Myo1c sites. The presence of 14-3-3β had little effect on the actin-activated ATPase or motile activities of Myo1c. Given these results, it is unlikely that 14-3-3β acts as a cargo adaptor for Myo1c-powered transport; rather, we propose that 14-3-3β binds Myo1c in the presence of calcium and stabilizes the calmodulin-dissociated, nonmotile myosin.
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Affiliation(s)
- Huan-Hong Ji
- Pennsylvania Muscle Institute, Department of Physiology, and Center for Engineering Mechanobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - E Michael Ostap
- Pennsylvania Muscle Institute, Department of Physiology, and Center for Engineering Mechanobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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17
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Eddington C, Titus MA. Putting the brakes on a myosin motor. J Biol Chem 2020; 295:3757-3758. [PMID: 32198186 DOI: 10.1074/jbc.h120.013153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-stimulated trafficking of GLUT4 requires the myosin motor Myo1C and signaling adaptor 14-3-3β. Originally, it was thought that 14-3-3β promotes GLUT4 transport by binding the Myo1C lever arm and activating the Myo1C motor. New work by Ji and Ostap using in vitro assays reveals that 14-3-3β binding actually inhibits Myo1C motility, prompting reconsideration of the functional relationship between 14-3-3β and Myo1C and the regulatory potential of atypical light chains.
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Affiliation(s)
- Casey Eddington
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Margaret A Titus
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
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18
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Minami S, Yokota N, Kawahara H. BAG6 contributes to glucose uptake by supporting the cell surface translocation of the glucose transporter GLUT4. Biol Open 2020; 9:bio.047324. [PMID: 31911483 PMCID: PMC6994957 DOI: 10.1242/bio.047324] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Defective translocation of glucose transporter 4 (GLUT4) to the cell surface is a key feature of insulin resistance in type 2 diabetes. Therefore, elucidating the mechanism of GLUT4 translocation is of primary importance. The mammalian Bag6/Bat3 gene has been suggested to be linked with potential obesity- and diabetes-associated loci, while its function in the control of glucose incorporation into the cytoplasm has not been investigated. In this study, we established a series of cell lines that stably expressed GLUT4 with three tandem repeats of the antigenic peptide inserted into its 1st extracellular loop. With these cell lines, we found that the depletion of endogenous BAG6 downregulated the cell surface expression of GLUT4, concomitant with the reduced incorporation of a glucose analog into the cells. Defective intracellular translocation of GLUT4 in BAG6-depleted cells is similar to the case observed for the depletion of Rab8a, an essential regulator of insulin-stimulated GLUT4 translocation. In addition, we observed that the assembly of syntaxin 6 into the endoplasmic reticulum membrane was slightly disturbed under BAG6 depletion. Given that Rab8a and syntaxin 6 are critical for GLUT4 translocation, we suggest that BAG6 may play multiple roles in the trafficking of glucose transporters to the cell surface. This article has an associated First Person interview with the first author of the paper. Summary: BAG6 is critical for the insulin-stimulated translocation of GLUT4 from its peri-nuclear storage compartments to the cell surface.
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Affiliation(s)
- Setsuya Minami
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Naoto Yokota
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Hiroyuki Kawahara
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
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19
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Zhang Y, Jiang X, Deng Q, Gao Z, Tang X, Fu R, Hu J, Li Y, Li L, Gao N. Downregulation of MYO1C mediated by cepharanthine inhibits autophagosome-lysosome fusion through blockade of the F-actin network. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:457. [PMID: 31699152 PMCID: PMC6836678 DOI: 10.1186/s13046-019-1449-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/15/2019] [Indexed: 01/10/2023]
Abstract
Background MYO1C, an actin-based motor protein, is involved in the late stages of autophagosome maturation and fusion with the lysosome. The molecular mechanism by which MYO1C regulates autophagosome-lysosome fusion remains largely unclear. Methods Western blotting was used to determine the expression of autophagy-related proteins. Transmission electron microscopy (TEM) was used to observe the ultrastructural changes. An immunoprecipitation assay was utilized to detect protein-protein interactions. Immunofluorescence analysis was used to detect autophagosome-lysosome fusion and colocalization of autophagy-related molecules. An overexpression plasmid or siRNA against MYO1C were sequentially introduced into human breast cancer MDA-MB-231 cells. Results We show here that cepharanthine (CEP), a novel autophagy inhibitor, inhibited autophagy/mitophagy through blockage of autophagosome-lysosome fusion in human breast cancer cells. Mechanistically, we found for the first time that MYO1C was downregulated by CEP treatment. Furthermore, the interaction/colocalization of MYO1C and F-actin with either LC3 or LAMP1 was inhibited by CEP treatment. Knockdown of MYO1C further decreased the interaction/colocalization of MYO1C and F-actin with either LC3 or LAMP1 inhibited by CEP treatment, leading to blockade of autophagosome-lysosome fusion. In contrast, overexpression of MYO1C significantly restored the interaction/colocalization of MYO1C and F-actin with either LC3 or LAMP1 inhibited by CEP treatment. Conclusion These findings highlight a key role of MYO1C in the regulation of autophagosome-lysosome fusion through F-actin remodeling. Our findings also suggest that CEP could potentially be further developed as a novel autophagy/mitophagy inhibitor, and a combination of CEP with classic chemotherapeutic drugs could become a promising treatment for breast cancer.
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Affiliation(s)
- Yanhao Zhang
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Xiuxing Jiang
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Qin Deng
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Ziyi Gao
- Greater Philadelphia Pharmacy, Philadelphia, USA
| | - Xiangyu Tang
- Biomedical Analysis Center, Army Medical University, Chongqing, 400038, China
| | - Ruoqiu Fu
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Jinjiao Hu
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Yunong Li
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Lirong Li
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China
| | - Ning Gao
- College of Pharmacy, Army Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing, 400038, China. .,Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China.
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20
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Abstract
A pivotal metabolic function of insulin is the stimulation of glucose uptake into muscle and adipose tissues. The discovery of the insulin-responsive glucose transporter type 4 (GLUT4) protein in 1988 inspired its molecular cloning in the following year. It also spurred numerous cellular mechanistic studies laying the foundations for how insulin regulates glucose uptake by muscle and fat cells. Here, we reflect on the importance of the GLUT4 discovery and chronicle additional key findings made in the past 30 years. That exocytosis of a multispanning membrane protein regulates cellular glucose transport illuminated a novel adaptation of the secretory pathway, which is to transiently modulate the protein composition of the cellular plasma membrane. GLUT4 controls glucose transport into fat and muscle tissues in response to insulin and also into muscle during exercise. Thus, investigation of regulated GLUT4 trafficking provides a major means by which to map the essential signaling components that transmit the effects of insulin and exercise. Manipulation of the expression of GLUT4 or GLUT4-regulating molecules in mice has revealed the impact of glucose uptake on whole-body metabolism. Remaining gaps in our understanding of GLUT4 function and regulation are highlighted here, along with opportunities for future discoveries and for the development of therapeutic approaches to manage metabolic disease.
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Affiliation(s)
- Amira Klip
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Timothy E McGraw
- Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10065
| | - David E James
- Charles Perkins Centre, School of Life and Environmental Sciences, Sydney Medical School, University of Sydney, Camperdown, New South Wales 2050, Australia
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21
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Arif E, Solanki AK, Srivastava P, Rahman B, Tash BR, Holzman LB, Janech MG, Martin R, Knölker HJ, Fitzgibbon WR, Deng P, Budisavljevic MN, Syn WK, Wang C, Lipschutz JH, Kwon SH, Nihalani D. The motor protein Myo1c regulates transforming growth factor-β-signaling and fibrosis in podocytes. Kidney Int 2019; 96:139-158. [PMID: 31097328 DOI: 10.1016/j.kint.2019.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/07/2019] [Accepted: 02/14/2019] [Indexed: 01/19/2023]
Abstract
Transforming growth factor-β (TGF-β) is known to play a critical role in the pathogenesis of many progressive podocyte diseases. However, the molecular mechanisms regulating TGF-β signaling in podocytes remain unclear. Using a podocyte-specific myosin (Myo)1c knockout, we demonstrate whether Myo1c is critical for TGF-β-signaling in podocyte disease pathogenesis. Specifically, podocyte-specific Myo1c knockout mice were resistant to fibrotic injury induced by Adriamycin or nephrotoxic serum. Further, loss of Myo1c also protected from injury in the TGF-β-dependent unilateral ureteral obstruction mouse model of renal interstitial fibrosis. Mechanistic analyses showed that loss of Myo1c significantly blunted TGF-β signaling through downregulation of canonical and non-canonical TGF-β pathways. Interestingly, nuclear rather than the cytoplasmic Myo1c was found to play a central role in controlling TGF-β signaling through transcriptional regulation. Differential expression analysis of nuclear Myo1c-associated gene promoters showed that nuclear Myo1c targeted the TGF-β responsive gene growth differentiation factor (GDF)-15 and directly bound to the GDF-15 promoter. Importantly, GDF15 was found to be involved in podocyte pathogenesis, where GDF15 was upregulated in glomeruli of patients with focal segmental glomerulosclerosis. Thus, Myo1c-mediated regulation of TGF-β-responsive genes is central to the pathogenesis of podocyte injury. Hence, inhibiting this process may have clinical application in treating podocytopathies.
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Affiliation(s)
- Ehtesham Arif
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Ashish K Solanki
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pankaj Srivastava
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Bushra Rahman
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Brian R Tash
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Lawrence B Holzman
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael G Janech
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA; College of Charleston, Charleston, South Carolina, USA
| | - René Martin
- Department of Chemistry, TU Dresden, Dresden, Germany
| | | | - Wayne R Fitzgibbon
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Peifeng Deng
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Milos N Budisavljevic
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Wing-Kin Syn
- Department of Gastroenterology & Hepatology, Medical University of South Carolina, Charleston, South Carolina, USA; Section of Gastroenterology, Ralph H Johnson VA Medical Center, Charleston, South Carolina, USA; Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country, (UPV/EHU), Vizcaya, Spain
| | - Cindy Wang
- Department of Gastroenterology & Hepatology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Joshua H Lipschutz
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Sang-Ho Kwon
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, USA
| | - Deepak Nihalani
- Department of Medicine, Nephrology Division, Medical University of South Carolina, Charleston, South Carolina, USA.
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22
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Capmany A, Yoshimura A, Kerdous R, Caorsi V, Lescure A, Nery ED, Coudrier E, Goud B, Schauer K. MYO1C stabilizes actin and facilitates arrival of transport carriers at the Golgi apparatus. J Cell Sci 2019; 132:jcs.225029. [DOI: 10.1242/jcs.225029] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 03/01/2019] [Indexed: 12/22/2022] Open
Abstract
We aim to identify the myosin motor proteins that control trafficking at the Golgi apparatus. In addition to the known Golgi-associated myosins MYO6, MYO18A and MYH9 (myosin IIA), we identify MYO1C as a novel player at the Golgi. We demonstrate that depletion of MYO1C induces Golgi apparatus fragmentation and decompaction. MYO1C accumulates at dynamic structures around the Golgi apparatus that colocalize with Golgi-associated actin dots. MYO1C depletion leads to loss of cellular F-actin, and Golgi apparatus decompaction is also observed after the inhibition or loss of the Arp2/3 complex. We show that the functional consequences of MYO1C depletion is a delay in the arrival of incoming transport carriers, both from the anterograde and retrograde routes. We propose that MYO1C stabilizes actin at the Golgi apparatus facilitating the arrival of incoming transport carriers at the Golgi.
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Affiliation(s)
- Anahi Capmany
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
| | - Azumi Yoshimura
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
| | - Rachid Kerdous
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
| | | | - Aurianne Lescure
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Department of Translational Research, BioPhenics High-Content Screening Laboratory, Cell and Tissue Imaging Facility (PICT-IBiSA), Paris, France
| | - Elaine Del Nery
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Department of Translational Research, BioPhenics High-Content Screening Laboratory, Cell and Tissue Imaging Facility (PICT-IBiSA), Paris, France
| | - Evelyne Coudrier
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
| | - Bruno Goud
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
| | - Kristine Schauer
- Institut Curie, PSL Research University, Molecular Mechanisms of Intracellular Transport group, 75248 Paris Cedex 05, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche144, 75005 Paris, France
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23
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Tokarz VL, MacDonald PE, Klip A. The cell biology of systemic insulin function. J Cell Biol 2018; 217:2273-2289. [PMID: 29622564 PMCID: PMC6028526 DOI: 10.1083/jcb.201802095] [Citation(s) in RCA: 230] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/21/2018] [Accepted: 03/23/2018] [Indexed: 12/12/2022] Open
Abstract
Insulin is the paramount anabolic hormone, promoting carbon energy deposition in the body. Its synthesis, quality control, delivery, and action are exquisitely regulated by highly orchestrated intracellular mechanisms in different organs or "stations" of its bodily journey. In this Beyond the Cell review, we focus on these five stages of the journey of insulin through the body and the captivating cell biology that underlies the interaction of insulin with each organ. We first analyze insulin's biosynthesis in and export from the β-cells of the pancreas. Next, we focus on its first pass and partial clearance in the liver with its temporality and periodicity linked to secretion. Continuing the journey, we briefly describe insulin's action on the blood vasculature and its still-debated mechanisms of exit from the capillary beds. Once in the parenchymal interstitium of muscle and adipose tissue, insulin promotes glucose uptake into myofibers and adipocytes, and we elaborate on the intricate signaling and vesicle traffic mechanisms that underlie this fundamental function. Finally, we touch upon the renal degradation of insulin to end its action. Cellular discernment of insulin's availability and action should prove critical to understanding its pivotal physiological functions and how their failure leads to diabetes.
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Affiliation(s)
- Victoria L Tokarz
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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24
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Koshida R, Tome S, Takei Y. Myosin Id localizes in dendritic spines through the tail homology 1 domain. Exp Cell Res 2018; 367:65-72. [PMID: 29559226 DOI: 10.1016/j.yexcr.2018.03.021] [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: 01/17/2018] [Revised: 03/15/2018] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
Abstract
Dendritic spines, the postsynaptic compartments at excitatory synapses, are capable of changing their shape and size to modulate synaptic transmission. The actin cytoskeleton and a variety of actin-binding proteins play a critical role in the dynamics of dendritic spines. Class I myosins are monomeric motor proteins that move along actin filaments using the energy of ATP hydrolysis. Of these class I myosins, myosin Id, the mammalian homolog of Drosophila Myo31DF, has been reported to be expressed in neurons, whereas its subcellular localization in neurons remained unknown. Here, we investigated the subcellular localization of myosin Id and determined the domain responsible for it. We found that myosin Id is enriched in the F-actin-rich pseudopodia of HEK293T cells and in the dendritic spines of primary hippocampal neurons. Both deletion and substitution of the tail homology 1 (TH1) domain drastically diminishes its colocalization with F-actin. In addition, the mutant form lacking the TH1 domain is less distributed in dendritic spines than is the full-length form. Taken together, our findings reveal that myosin Id localizes in dendritic spines through the TH1 domain.
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Affiliation(s)
- Ryusuke Koshida
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan.
| | - Saki Tome
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Yosuke Takei
- Department of Anatomy and Neuroscience, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8577, Japan.
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25
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Dissanayake WC, Sorrenson B, Cognard E, Hughes WE, Shepherd PR. β-catenin is important for the development of an insulin responsive pool of GLUT4 glucose transporters in 3T3-L1 adipocytes. Exp Cell Res 2018. [PMID: 29540328 DOI: 10.1016/j.yexcr.2018.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
GLUT4 is unique among specialized glucose transporters in being exclusively expressed in muscle and adipocytes. In the absence of insulin the distribution of GLUT4 is preferentially intracellular and insulin stimulation results in the movement of GLUT4 containing vesicles to the plasma membrane. This process is responsible for the insulin stimulation of glucose uptake in muscle and fat. While signalling pathways triggering the translocation of GLUT4 are well understood, the mechanisms regulating the intracellular retention of GLUT4 are less well understood. Here we report a role for β-catenin in this process. In 3T3-L1 adipocytes in which β-catenin is depleted, the levels of GLUT4 at and near the plasma membrane rise in unstimulated cells while the subsequent increase in GLUT4 at the plasma membrane upon insulin stimulation is reduced. Small molecule approaches to acutely activate or inhibit β-catenin give results that support the results obtained with siRNA and these changes are accompanied by matching changes in glucose transport into these cells. Together these results indicate that β-catenin is a previously unrecognized regulator of the mechanisms that control the insulin sensitive pool of GLUT4 transporters inside these adipocyte cells.
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Affiliation(s)
- Waruni C Dissanayake
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Brie Sorrenson
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Emmanuelle Cognard
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - William E Hughes
- Department of Medicine, St. Vincent's Hospital, Victoria Street, Sydney 2010, Australia; The Garvan Institute of Medical Research, 384 Victoria Street, Sydney 2010, Australia
| | - Peter R Shepherd
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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26
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McIntosh BB, Pyrpassopoulos S, Holzbaur ELF, Ostap EM. Opposing Kinesin and Myosin-I Motors Drive Membrane Deformation and Tubulation along Engineered Cytoskeletal Networks. Curr Biol 2018; 28:236-248.e5. [PMID: 29337076 DOI: 10.1016/j.cub.2017.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 09/29/2017] [Accepted: 12/07/2017] [Indexed: 01/22/2023]
Abstract
Microtubule and actin filament molecular motors such as kinesin-1 and myosin-Ic (Myo1c) transport and remodel membrane-bound vesicles; however, it is unclear how they coordinate to accomplish these tasks. We introduced kinesin-1- and Myo1c-bound giant unilamellar vesicles (GUVs) into a micropatterned in vitro cytoskeletal matrix modeled after the subcellular architecture where vesicular sorting and membrane remodeling are observed. This array was composed of sparse microtubules intersecting regions dense with actin filaments, and revealed that Myo1c-dependent tethering of GUVs enabled kinesin-1-driven membrane deformation and tubulation. Membrane remodeling at actin/microtubule intersections was modulated by lipid composition and the addition of the Bin-Amphiphysin-Rvs-domain (BAR-domain) proteins endophilin or FCH-domain-only (FCHo). Myo1c not only tethered microtubule-transported cargo, but also transported, deformed, and tubulated GUVs along actin filaments in a lipid-composition- and BAR-protein-responsive manner. These results suggest a mechanism for actin-based involvement in vesicular transport and remodeling of intracellular membranes, and implicate lipid composition as a key factor in determining whether vesicles will undergo transport, deformation, or tubulation driven by opposing actin and microtubule motors and BAR-domain proteins.
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Affiliation(s)
- Betsy B McIntosh
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; Center for Engineering MechanoBiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Serapion Pyrpassopoulos
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; Center for Engineering MechanoBiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Erika L F Holzbaur
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; Center for Engineering MechanoBiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA.
| | - E Michael Ostap
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; Center for Engineering MechanoBiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA.
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27
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Jaldin-Fincati JR, Bilan PJ, Klip A. GLUT4 Translocation in Single Muscle Cells in Culture: Epitope Detection by Immunofluorescence. Methods Mol Biol 2018; 1713:175-192. [PMID: 29218526 DOI: 10.1007/978-1-4939-7507-5_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
GLUT4 is the major glucose transporter in skeletal muscle. GLUT4 cycles to and from the plasma membrane and its exocytic rate is accelerated by insulin and muscle contraction to achieve a new steady state with more GLUT4 proteins at the muscle cell surface. To gain a better understanding of the molecular and cellular mechanisms that govern GLUT4 protein recycling, we developed an in vitro model in which myc-epitope-tagged GLUT4 or GLUT4-GFP is expressed in L6 skeletal muscle cells. The myc-epitope is inserted into an exofacial domain that is accessible to anti-myc antibodies from the outside of non-permeabilized cells, allowing one to count the number of transporters at the cell surface. This enables one to perform single-cell analysis using confocal fluorescence microscopy to quantify cell surface GLUT4myc or GLUT4myc-GFP in cells co-transfected with diverse cDNA constructs, treated with siRNAs, or co-stained with antibodies for other proteins of interest. Herein, we describe the methodology to perform these experimental approaches in insulin-stimulated L6 muscle cells.
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Affiliation(s)
- Javier R Jaldin-Fincati
- Cell Biology Program, Research Institute, The Hospital for Sick Children, 686 Bay Street, PGCRL, Room 19.9709, Toronto, ON, Canada, M5G 0A4
| | - Philip J Bilan
- Cell Biology Program, Research Institute, The Hospital for Sick Children, 686 Bay Street, PGCRL, Room 19.9709, Toronto, ON, Canada, M5G 0A4
| | - Amira Klip
- Cell Biology Program, Research Institute, The Hospital for Sick Children, 686 Bay Street, PGCRL, Room 19.9709, Toronto, ON, Canada, M5G 0A4.
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28
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Jaldin-Fincati JR, Pavarotti M, Frendo-Cumbo S, Bilan PJ, Klip A. Update on GLUT4 Vesicle Traffic: A Cornerstone of Insulin Action. Trends Endocrinol Metab 2017; 28:597-611. [PMID: 28602209 DOI: 10.1016/j.tem.2017.05.002] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/08/2017] [Accepted: 05/09/2017] [Indexed: 12/20/2022]
Abstract
Glucose transport is rate limiting for dietary glucose utilization by muscle and fat. The glucose transporter GLUT4 is dynamically sorted and retained intracellularly and redistributes to the plasma membrane (PM) by insulin-regulated vesicular traffic, or 'GLUT4 translocation'. Here we emphasize recent findings in GLUT4 translocation research. The application of total internal reflection fluorescence microscopy (TIRFM) has increased our understanding of insulin-regulated events beneath the PM, such as vesicle tethering and membrane fusion. We describe recent findings on Akt-targeted Rab GTPase-activating proteins (GAPs) (TBC1D1, TBC1D4, TBC1D13) and downstream Rab GTPases (Rab8a, Rab10, Rab13, Rab14, and their effectors) along with the input of Rac1 and actin filaments, molecular motors [myosinVa (MyoVa), myosin1c (Myo1c), myosinIIA (MyoIIA)], and membrane fusion regulators (syntaxin4, munc18c, Doc2b). Collectively these findings reveal novel events in insulin-regulated GLUT4 traffic.
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Affiliation(s)
| | - Martin Pavarotti
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5J 2L4, Canada; IHEM, Universidad Nacional de Cuyo, CONICET, Mendoza 5500, Argentina
| | - Scott Frendo-Cumbo
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5J 2L4, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Philip J Bilan
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5J 2L4, Canada
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5J 2L4, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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29
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González-Jamett AM, Baez-Matus X, Olivares MJ, Hinostroza F, Guerra-Fernández MJ, Vasquez-Navarrete J, Bui MT, Guicheney P, Romero NB, Bevilacqua JA, Bitoun M, Caviedes P, Cárdenas AM. Dynamin-2 mutations linked to Centronuclear Myopathy impair actin-dependent trafficking in muscle cells. Sci Rep 2017; 7:4580. [PMID: 28676641 PMCID: PMC5496902 DOI: 10.1038/s41598-017-04418-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 05/16/2017] [Indexed: 12/20/2022] Open
Abstract
Dynamin-2 is a ubiquitously expressed GTP-ase that mediates membrane remodeling. Recent findings indicate that dynamin-2 also regulates actin dynamics. Mutations in dynamin-2 cause dominant centronuclear myopathy (CNM), a congenital myopathy characterized by progressive weakness and atrophy of skeletal muscles. However, the muscle-specific roles of dynamin-2 affected by these mutations remain elusive. Here we show that, in muscle cells, the GTP-ase activity of dynamin-2 is involved in de novo actin polymerization as well as in actin-mediated trafficking of the glucose transporter GLUT4. Expression of dynamin-2 constructs carrying CNM-linked mutations disrupted the formation of new actin filaments as well as the stimulus-induced translocation of GLUT4 to the plasma membrane. Similarly, mature muscle fibers isolated from heterozygous knock-in mice that harbor the dynamin-2 mutation p.R465W, an animal model of CNM, exhibited altered actin organization, reduced actin polymerization and impaired insulin-induced translocation of GLUT4 to the sarcolemma. Moreover, GLUT4 displayed aberrant perinuclear accumulation in biopsies from CNM patients carrying dynamin-2 mutations, further suggesting trafficking defects. These results suggest that dynamin-2 is a key regulator of actin dynamics and GLUT4 trafficking in muscle cells. Our findings also support a model in which impairment of actin-dependent trafficking contributes to the pathological mechanism in dynamin-2-associated CNM.
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Affiliation(s)
- Arlek M González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile. .,Programa de Farmacología Molecular y Clinica, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
| | - Ximena Baez-Matus
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - María José Olivares
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Fernando Hinostroza
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Doctorado en Ciencias, mención Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Maria José Guerra-Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Jacqueline Vasquez-Navarrete
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Mai Thao Bui
- Université Sorbonne, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France.,Centre de référence de Pathologie Neuromusculaire Paris-Est, Institut de Myologie, GHU Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, GH Pitié-Salpêtrière, Paris, France
| | - Pascale Guicheney
- INSERM, UMR_S1166, Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Norma Beatriz Romero
- Université Sorbonne, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France.,Centre de référence de Pathologie Neuromusculaire Paris-Est, Institut de Myologie, GHU Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, GH Pitié-Salpêtrière, Paris, France
| | - Jorge A Bevilacqua
- Programa de Anatomía y Biología del Desarrollo, ICBM, Facultad de Medicina, Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile, Universidad de Chile, Santiago, Chile
| | - Marc Bitoun
- Research Center for Myology, UPMC Univ Paris 06 and INSERM UMRS 974, Institute of Myology, Paris, France
| | - Pablo Caviedes
- Programa de Farmacología Molecular y Clinica, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso. Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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30
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Beg M, Abdullah N, Thowfeik FS, Altorki NK, McGraw TE. Distinct Akt phosphorylation states are required for insulin regulated Glut4 and Glut1-mediated glucose uptake. eLife 2017; 6. [PMID: 28589878 PMCID: PMC5462539 DOI: 10.7554/elife.26896] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/22/2017] [Indexed: 01/01/2023] Open
Abstract
Insulin, downstream of Akt activation, promotes glucose uptake into fat and muscle cells to lower postprandial blood glucose, an enforced change in cellular metabolism to maintain glucose homeostasis. This effect is mediated by the Glut4 glucose transporter. Growth factors also enhance glucose uptake to fuel an anabolic metabolism required for tissue growth and repair. This activity is predominantly mediated by the Glut1. Akt is activated by phosphorylation of its kinase and hydrophobic motif (HM) domains. We show that insulin-stimulated Glut4-mediated glucose uptake requires PDPK1 phosphorylation of the kinase domain but not mTORC2 phosphorylation of the HM domain. Nonetheless, an intact HM domain is required for Glut4-mediated glucose uptake. Whereas, Glut1-mediated glucose uptake also requires mTORC2 phosphorylation of the HM domain, demonstrating both phosphorylation-dependent and independent roles of the HM domain in regulating glucose uptake. Thus, mTORC2 links Akt to the distinct physiologic programs related to Glut4 and Glut1-mediated glucose uptake. DOI:http://dx.doi.org/10.7554/eLife.26896.001
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Affiliation(s)
- Muheeb Beg
- Department of Biochemistry, Weill Cornell Medicine, New York, United States
| | - Nazish Abdullah
- Department of Biochemistry, Weill Cornell Medicine, New York, United States
| | - Fathima Shazna Thowfeik
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, United States.,Lung Cancer Program, Meyer Cancer Center, Weill Cornell Medicine, New York, United States
| | - Nasser K Altorki
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, United States.,Lung Cancer Program, Meyer Cancer Center, Weill Cornell Medicine, New York, United States
| | - Timothy E McGraw
- Department of Biochemistry, Weill Cornell Medicine, New York, United States.,Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, United States.,Lung Cancer Program, Meyer Cancer Center, Weill Cornell Medicine, New York, United States
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31
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Tunduguru R, Thurmond DC. Promoting Glucose Transporter-4 Vesicle Trafficking along Cytoskeletal Tracks: PAK-Ing Them Out. Front Endocrinol (Lausanne) 2017; 8:329. [PMID: 29209279 PMCID: PMC5701999 DOI: 10.3389/fendo.2017.00329] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/06/2017] [Indexed: 12/27/2022] Open
Abstract
Glucose is the principal cellular energy source in humans and maintenance of glucose homeostasis is critical for survival. Glucose uptake into peripheral skeletal muscle and adipose tissues requires the trafficking of vesicles containing glucose transporter-4 (GLUT4) from the intracellular storage compartments to the cell surface. Trafficking of GLUT4 storage vesicles is initiated via the canonical insulin signaling cascade in skeletal muscle and fat cells, as well as via exercise-induced contraction in muscle cells. Recent studies have elucidated steps in the signaling cascades that involve remodeling of the cytoskeleton, a process that underpins the mechanical movement of GLUT4 vesicles. This review is focused upon an alternate phosphoinositide-3 kinase-dependent pathway involving Ras-related C3 botulinum toxin substrate 1 signaling through the p21-activated kinase p21-activated kinase 1 and showcases related signaling events that co-regulate both the depolymerization and re-polymerization of filamentous actin. These new insights provide an enriched understanding into the process of glucose transport and yield potential new targets for interventions aimed to improve insulin sensitivity and remediate insulin resistance, pre-diabetes, and the progression to type 2 diabetes.
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Affiliation(s)
- Ragadeepthi Tunduguru
- Department of Molecular and Cellular Endocrinology, Diabetes and Metabolism Research Institute of City of Hope, Duarte, CA, United States
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Diabetes and Metabolism Research Institute of City of Hope, Duarte, CA, United States
- *Correspondence: Debbie C. Thurmond,
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32
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Esteves JV, Enguita FJ, Machado UF. MicroRNAs-Mediated Regulation of Skeletal Muscle GLUT4 Expression and Translocation in Insulin Resistance. J Diabetes Res 2017; 2017:7267910. [PMID: 28428964 PMCID: PMC5385897 DOI: 10.1155/2017/7267910] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/22/2017] [Accepted: 02/27/2017] [Indexed: 01/12/2023] Open
Abstract
The solute carrier family 2 facilitated glucose transporter member 4 (GLUT4) plays a key role in the insulin-induced glucose uptake by muscle and adipose tissues. In prediabetes and diabetes, GLUT4 expression/translocation has been detected as reduced, participating in mechanisms that impair glycemic control. Recently, a class of short endogenous noncoding RNAs named microRNAs (miRNAs) has been increasingly described as involved in the posttranscriptional epigenetic regulation of gene expression. The present review focuses on miRNAs potentially involved in the expression of GLUT4 expression, and proteins related to GLUT4 and translocation in skeletal muscle, seeking to correlate them with insulin resistance and diabetes. So far, miR-21a-5p, miR-29a-3p, miR-29c-3p, miR-93-5p, miR-106b-5p, miR-133a-3p, miR-133b-3p, miR-222-3p, and miR-223-3p have been reported to directly and/or indirectly regulate the GLUT4 expression; and their expression is altered under diabetes-related conditions. Besides, some miRNAs that have been linked to the expression of proteins involved in GLUT4 translocation machinery in muscle could also impact glucose uptake. That makes these miRNAs promising targets for preventive and/or therapeutic approaches, which could improve glycemic control, thus deserving future new investigations.
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Affiliation(s)
- João Victor Esteves
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Francisco Javier Enguita
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ubiratan Fabres Machado
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
- *Ubiratan Fabres Machado:
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Visuttijai K, Pettersson J, Mehrbani Azar Y, van den Bout I, Örndal C, Marcickiewicz J, Nilsson S, Hörnquist M, Olsson B, Ejeskär K, Behboudi A. Lowered Expression of Tumor Suppressor Candidate MYO1C Stimulates Cell Proliferation, Suppresses Cell Adhesion and Activates AKT. PLoS One 2016; 11:e0164063. [PMID: 27716847 PMCID: PMC5055341 DOI: 10.1371/journal.pone.0164063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 09/18/2016] [Indexed: 12/12/2022] Open
Abstract
Myosin-1C (MYO1C) is a tumor suppressor candidate located in a region of recurrent losses distal to TP53. Myo1c can tightly and specifically bind to PIP2, the substrate of Phosphoinositide 3-kinase (PI3K), and to Rictor, suggesting a role for MYO1C in the PI3K pathway. This study was designed to examine MYO1C expression status in a panel of well-stratified endometrial carcinomas as well as to assess the biological significance of MYO1C as a tumor suppressor in vitro. We found a significant correlation between the tumor stage and lowered expression of MYO1C in endometrial carcinoma samples. In cell transfection experiments, we found a negative correlation between MYO1C expression and cell proliferation, and MYO1C silencing resulted in diminished cell migration and adhesion. Cells expressing excess of MYO1C had low basal level of phosphorylated protein kinase B (PKB, a.k.a. AKT) and cells with knocked down MYO1C expression showed a quicker phosphorylated AKT (pAKT) response in reaction to serum stimulation. Taken together the present study gives further evidence for tumor suppressor activity of MYO1C and suggests MYO1C mediates its tumor suppressor function through inhibition of PI3K pathway and its involvement in loss of contact inhibition.
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Affiliation(s)
- Kittichate Visuttijai
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
- Department of Medical and Clinical Genetics, Sahlgrenska Academy, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - Jennifer Pettersson
- Department of Medical and Clinical Genetics, Sahlgrenska Academy, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - Yashar Mehrbani Azar
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Iman van den Bout
- Department of physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, 0007, South Africa
| | - Charlotte Örndal
- Department of Pathology, Sahlgrenska University Hospital, SE-413 45, Gothenburg, Sweden
| | - Janusz Marcickiewicz
- Department of Obstetrics and Gynecology, Halland Hospital Varberg, SE- 432 37, Varberg, Sweden
| | - Staffan Nilsson
- Institute of Mathematical Statistics, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Michael Hörnquist
- Department of Science and Technology, University of Linköping, ITN, SE-601 74, Norrköping, Sweden
| | - Björn Olsson
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Katarina Ejeskär
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Afrouz Behboudi
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
- * E-mail:
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Finkenstaedt-Quinn SA, Qiu TA, Shin K, Haynes CL. Super-resolution imaging for monitoring cytoskeleton dynamics. Analyst 2016; 141:5674-5688. [PMID: 27549146 DOI: 10.1039/c6an00731g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cytoskeleton is a key cellular structure that is important in the control of cellular movement, structure, and sensing. To successfully image the individual cytoskeleton components, high resolution and super-resolution fluorescence imaging methods are needed. This review covers the three basic cytoskeletal elements and the relative benefits and drawbacks of fixed versus live cell imaging before moving on to recent studies using high resolution and super-resolution techniques. The techniques covered include the near-diffraction limited imaging methods of confocal microscopy and TIRF microscopy and the super-resolution fluorescence imaging methods of STORM, PALM, and STED.
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35
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Abstract
Myosin-I molecular motors are proposed to play various cellular roles related to membrane dynamics and trafficking. In this Cell Science at a Glance article and the accompanying poster, we review and illustrate the proposed cellular functions of metazoan myosin-I molecular motors by examining the structural, biochemical, mechanical and cell biological evidence for their proposed molecular roles. We highlight evidence for the roles of myosin-I isoforms in regulating membrane tension and actin architecture, powering plasma membrane and organelle deformation, participating in membrane trafficking, and functioning as a tension-sensitive dock or tether. Collectively, myosin-I motors have been implicated in increasingly complex cellular phenomena, yet how a single isoform accomplishes multiple types of molecular functions is still an active area of investigation. To fully understand the underlying physiology, it is now essential to piece together different approaches of biological investigation. This article will appeal to investigators who study immunology, metabolic diseases, endosomal trafficking, cell motility, cancer and kidney disease, and to those who are interested in how cellular membranes are coupled to the underlying actin cytoskeleton in a variety of different applications.
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Affiliation(s)
- Betsy B McIntosh
- Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - E Michael Ostap
- Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
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36
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Structural Analysis of the Myo1c and Neph1 Complex Provides Insight into the Intracellular Movement of Neph1. Mol Cell Biol 2016; 36:1639-54. [PMID: 27044863 DOI: 10.1128/mcb.00020-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/21/2016] [Indexed: 11/20/2022] Open
Abstract
The Myo1c motor functions as a cargo transporter supporting various cellular events, including vesicular trafficking, cell migration, and stereociliary movements of hair cells. Although its partial crystal structures were recently described, the structural details of its interaction with cargo proteins remain unknown. This study presents the first structural demonstration of a cargo protein, Neph1, attached to Myo1c, providing novel insights into the role of Myo1c in intracellular movements of this critical slit diaphragm protein. Using small angle X-ray scattering studies, models of predominant solution conformation of unliganded full-length Myo1c and Myo1c bound to Neph1 were constructed. The resulting structures show an extended S-shaped Myo1c with Neph1 attached to its C-terminal tail. Importantly, binding of Neph1 did not induce a significant shape change in Myo1c, indicating this as a spontaneous process or event. Analysis of interaction surfaces led to the identification of a critical residue in Neph1 involved in binding to Myo1c. Indeed, a point mutant from this site abolished interaction between Neph1 and Myo1c when tested in the in vitro and in live-cell binding assays. Live-cell imaging, including fluorescence recovery after photobleaching, provided further support for the role of Myo1c in intracellular vesicular movement of Neph1 and its turnover at the membrane.
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Kittelberger N, Breunig M, Martin R, Knölker HJ, Miklavc P. The role of myosin 1c and myosin 1b in surfactant exocytosis. J Cell Sci 2016; 129:1685-96. [PMID: 26940917 PMCID: PMC4852769 DOI: 10.1242/jcs.181313] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/25/2016] [Indexed: 12/19/2022] Open
Abstract
Actin and actin-associated proteins have a pivotal effect on regulated exocytosis in secretory cells and influence pre-fusion as well as post-fusion stages of exocytosis. Actin polymerization on secretory granules during the post-fusion phase (formation of an actin coat) is especially important in cells with large secretory vesicles or poorly soluble secretions. Alveolar type II (ATII) cells secrete hydrophobic lipo-protein surfactant, which does not easily diffuse from fused vesicles. Previous work showed that compression of actin coat is necessary for surfactant extrusion. Here, we investigate the role of class 1 myosins as possible linkers between actin and membranes during exocytosis. Live-cell microscopy showed translocation of fluorescently labeled myosin 1b and myosin 1c to the secretory vesicle membrane after fusion. Myosin 1c translocation was dependent on its pleckstrin homology domain. Expression of myosin 1b and myosin 1c constructs influenced vesicle compression rate, whereas only the inhibition of myosin 1c reduced exocytosis. These findings suggest that class 1 myosins participate in several stages of ATII cell exocytosis and link actin coats to the secretory vesicle membrane to influence vesicle compression.
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Affiliation(s)
- Nadine Kittelberger
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
| | - Markus Breunig
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
| | - René Martin
- Department of Chemistry, Technische Universität Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Hans-Joachim Knölker
- Department of Chemistry, Technische Universität Dresden, Bergstr. 66, Dresden 01069, Germany
| | - Pika Miklavc
- Institute of General Physiology, Ulm University, Albert-Einstein Allee 11, Ulm 89081, Germany
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Sun Y, Jaldin-Fincati J, Liu Z, Bilan PJ, Klip A. A complex of Rab13 with MICAL-L2 and α-actinin-4 is essential for insulin-dependent GLUT4 exocytosis. Mol Biol Cell 2015; 27:75-89. [PMID: 26538022 PMCID: PMC4694764 DOI: 10.1091/mbc.e15-05-0319] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/26/2015] [Indexed: 01/11/2023] Open
Abstract
Rab13 is necessary for insulin-regulated GLUT4-vesicle exocytosis in muscle. Biochemical and imaging analyses provide evidence that activated Rab13 engages a scaffold protein MICAL-L2 to form a complex with Rab13 and α-actinin-4. Through GLUT4 interaction with α-actinin-4, GLUT4 vesicles are recruited to the muscle plasma membrane. Insulin promotes glucose uptake into skeletal muscle through recruitment of glucose transporter 4 (GLUT4) to the plasma membrane. Rab GTPases are molecular switches mobilizing intracellular vesicles, and Rab13 is necessary for insulin-regulated GLUT4–vesicle exocytic translocation in muscle cells. We show that Rab13 engages the scaffold protein MICAL-L2 in this process. RNA interference–mediated knockdown of MICAL-L2 or truncated MICAL-L2 (MICAL-L2-CT) impaired insulin-stimulated GLUT4 translocation. Insulin increased Rab13 binding to MICAL-L2, assessed by pull down and colocalization under confocal fluorescence and structured illumination microscopies. Association was also visualized at the cell periphery using TIRF microscopy. Insulin further increased binding of MICAL-L2 to α-actinin-4 (ACTN4), a protein involved in GLUT4 translocation. Rab13, MICAL-L2, and ACTN4 formed an insulin-dependent complex assessed by pull down and confocal fluorescence imaging. Of note, GLUT4 associated with the complex in response to insulin, requiring the ACTN4-binding domain in MICAL-L2. This was demonstrated by pull down with distinct fragments of MICAL-L2 and confocal and structured illumination microscopies. Finally, expression of MICAL-L2-CT abrogated the insulin-dependent colocalization of Rab13 with ACTN4 or Rab13 with GLUT4. Our findings suggest that MICAL-L2 is an effector of insulin-activated Rab13, which links to GLUT4 through ACTN4, localizing GLUT4 vesicles at the muscle cell periphery to enable their fusion with the membrane.
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Affiliation(s)
- Yi Sun
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | | | - Zhi Liu
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Philip J Bilan
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Amira Klip
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
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Komaba S, Coluccio LM. Myosin 1b Regulates Amino Acid Transport by Associating Transporters with the Apical Plasma Membrane of Kidney Cells. PLoS One 2015; 10:e0138012. [PMID: 26361046 PMCID: PMC4567078 DOI: 10.1371/journal.pone.0138012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 08/24/2015] [Indexed: 01/11/2023] Open
Abstract
Amino acid transporters (AATers) in the brush border of the apical plasma membrane (APM) of renal proximal tubule (PT) cells mediate amino acid transport (AAT). We found that the membrane-associated class I myosin myosin 1b (Myo1b) localized at the apical brush border membrane of PTs. In opossum kidney (OK) 3B/2 epithelial cells, which are derived from PTs, expressed rat Myo1b-GFP colocalized in patched microvilli with expressed mouse V5-tagged SIT1 (SIT1-V5), which mediates neutral amino acid transport in OK cells. Lentivirus-mediated delivery of opossum Myo1b-specific shRNA resulted in knockdown (kd) of Myo1b expression, less SIT1-V5 at the APM as determined by localization studies, and a decrease in neutral AAT as determined by radioactive uptake assays. Myo1b kd had no effect on Pi transport or noticeable change in microvilli structure as determined by rhodamine phalloidin staining. The studies are the first to define a physiological role for Myo1b, that of regulating renal AAT by modulating the association of AATers with the APM.
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Affiliation(s)
- Shigeru Komaba
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Lynne M. Coluccio
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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40
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Kee AJ, Yang L, Lucas CA, Greenberg MJ, Martel N, Leong GM, Hughes WE, Cooney GJ, James DE, Ostap EM, Han W, Gunning PW, Hardeman EC. An actin filament population defined by the tropomyosin Tpm3.1 regulates glucose uptake. Traffic 2015; 16:691-711. [PMID: 25783006 PMCID: PMC4945106 DOI: 10.1111/tra.12282] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 03/10/2015] [Accepted: 03/11/2015] [Indexed: 12/21/2022]
Abstract
Actin has an ill-defined role in the trafficking of GLUT4 glucose transporter vesicles to the plasma membrane (PM). We have identified novel actin filaments defined by the tropomyosin Tpm3.1 at glucose uptake sites in white adipose tissue (WAT) and skeletal muscle. In Tpm 3.1-overexpressing mice, insulin-stimulated glucose uptake was increased; while Tpm3.1-null mice they were more sensitive to the impact of high-fat diet on glucose uptake. Inhibition of Tpm3.1 function in 3T3-L1 adipocytes abrogates insulin-stimulated GLUT4 translocation and glucose uptake. In WAT, the amount of filamentous actin is determined by Tpm3.1 levels and is paralleled by changes in exocyst component (sec8) and Myo1c levels. In adipocytes, Tpm3.1 localizes with MyoIIA, but not Myo1c, and it inhibits Myo1c binding to actin. We propose that Tpm3.1 determines the amount of cortical actin that can engage MyoIIA and generate contractile force, and in parallel limits the interaction of Myo1c with actin filaments. The balance between these actin filament populations may determine the efficiency of movement and/or fusion of GLUT4 vesicles with the PM.
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Affiliation(s)
- Anthony J. Kee
- Cellular and Genetic Medicine UnitSchool of Medical Sciences, UNSW AustraliaSydneyNSW2052Australia
| | - Lingyan Yang
- Cellular and Genetic Medicine UnitSchool of Medical Sciences, UNSW AustraliaSydneyNSW2052Australia
| | - Christine A. Lucas
- Cellular and Genetic Medicine UnitSchool of Medical Sciences, UNSW AustraliaSydneyNSW2052Australia
| | - Michael J. Greenberg
- The Pennsylvania Muscle Institute and Department of PhysiologyPerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA19104‐6085USA
| | - Nick Martel
- Obesity Research Centre, Institute for Molecular BioscienceThe University of QueenslandSt LuciaQLD4072Australia
| | - Gary M. Leong
- Obesity Research Centre, Institute for Molecular BioscienceThe University of QueenslandSt LuciaQLD4072Australia
- Department of Paediatric Endocrinology and DiabetesMater Children's HospitalSouth BrisbaneQLD4010Australia
| | - William E. Hughes
- Diabetes and Obesity ProgramGarvan Institute of Medical ResearchSydneyNSW2010Australia
| | - Gregory J. Cooney
- Diabetes and Obesity ProgramGarvan Institute of Medical ResearchSydneyNSW2010Australia
| | - David E. James
- Charles Perkins Centre, School of Molecular BioscienceUniversity of SydneySydneyNSW2006Australia
| | - E. Michael Ostap
- The Pennsylvania Muscle Institute and Department of PhysiologyPerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA19104‐6085USA
| | - Weiping Han
- Singapore Bioimaging ConsortiumAgency for Science, Technology and Research (A*STAR)Singapore138667Singapore
| | - Peter W. Gunning
- Oncology Research UnitSchool of Medical Sciences, UNSW AustraliaSydneyNSW2052Australia
| | - Edna C. Hardeman
- Cellular and Genetic Medicine UnitSchool of Medical Sciences, UNSW AustraliaSydneyNSW2052Australia
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Glade MJ, Smith K. A glance at … exercise and glucose uptake. Nutrition 2015; 31:893-7. [PMID: 25933500 DOI: 10.1016/j.nut.2014.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/03/2014] [Indexed: 10/24/2022]
Affiliation(s)
| | - Kyl Smith
- Progressive Laboratories Inc., Irving, Texas
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42
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McIntosh BB, Holzbaur ELF, Ostap EM. Control of the initiation and termination of kinesin-1-driven transport by myosin-Ic and nonmuscle tropomyosin. Curr Biol 2015; 25:523-9. [PMID: 25660542 DOI: 10.1016/j.cub.2014.12.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/14/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
Intracellular transport is largely driven by processive microtubule- and actin-based molecular motors. Nonprocessive motors have also been localized to trafficking cargos, but their roles are not well understood. Myosin-Ic (Myo1c), a nonprocessive actin motor, functions in a variety of exocytic events, although the underlying mechanisms are not yet clear. To investigate the interplay between myosin-I and the canonical long-distance transport motor kinesin-1, we attached both motor types to lipid membrane-coated bead cargo, using an attachment strategy that allows motors to actively reorganize within the membrane in response to the local cytoskeletal environment. We compared the motility of kinesin-1-driven cargos in the absence and presence of Myo1c at engineered actin/microtubule intersections. We found that Myo1c significantly increases the frequency of kinesin-1-driven microtubule-based runs that begin at actin/microtubule intersections. Myo1c also regulates the termination of processive runs. Beads with both motors bound have a significantly higher probability of pausing at actin/microtubule intersections, remaining tethered for an average of 20 s, with some pauses lasting longer than 200 s. The actin-binding protein nonmuscle tropomyosin (Tm) provides spatially specific regulation of interactions between myosin motors and actin filaments in vivo; in the crossed-filament in vitro assay, we found that Tm2-actin abolishes Myo1c-specific effects on both run initiation and run termination. Together, these observations suggest Myo1c is important for the selective initiation and termination of kinesin-1-driven runs along microtubules at specific actin filament populations within the cell.
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Affiliation(s)
- Betsy B McIntosh
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Erika L F Holzbaur
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA.
| | - E Michael Ostap
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA.
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Benton MC, Johnstone A, Eccles D, Harmon B, Hayes MT, Lea RA, Griffiths L, Hoffman EP, Stubbs RS, Macartney-Coxson D. An analysis of DNA methylation in human adipose tissue reveals differential modification of obesity genes before and after gastric bypass and weight loss. Genome Biol 2015; 16:8. [PMID: 25651499 PMCID: PMC4301800 DOI: 10.1186/s13059-014-0569-x] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 12/11/2014] [Indexed: 12/18/2022] Open
Abstract
Background Environmental factors can influence obesity by epigenetic mechanisms. Adipose tissue plays a key role in obesity-related metabolic dysfunction, and gastric bypass provides a model to investigate obesity and weight loss in humans. Results Here, we investigate DNA methylation in adipose tissue from obese women before and after gastric bypass and significant weight loss. In total, 485,577 CpG sites were profiled in matched, before and after weight loss, subcutaneous and omental adipose tissue. A paired analysis revealed significant differential methylation in omental and subcutaneous adipose tissue. A greater proportion of CpGs are hypermethylated before weight loss and increased methylation is observed in the 3′ untranslated region and gene bodies relative to promoter regions. Differential methylation is found within genes associated with obesity, epigenetic regulation and development, such as CETP, FOXP2, HDAC4, DNMT3B, KCNQ1 and HOX clusters. We identify robust correlations between changes in methylation and clinical trait, including associations between fasting glucose and HDAC4, SLC37A3 and DENND1C in subcutaneous adipose. Genes investigated with differential promoter methylation all show significantly different levels of mRNA before and after gastric bypass. Conclusions This is the first study reporting global DNA methylation profiling of adipose tissue before and after gastric bypass and associated weight loss. It provides a strong basis for future work and offers additional evidence for the role of DNA methylation of adipose tissue in obesity. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0569-x) contains supplementary material, which is available to authorized users.
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44
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Tropomodulin3 is a novel Akt2 effector regulating insulin-stimulated GLUT4 exocytosis through cortical actin remodeling. Nat Commun 2015; 6:5951. [PMID: 25575350 PMCID: PMC4354152 DOI: 10.1038/ncomms6951] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/25/2014] [Indexed: 12/19/2022] Open
Abstract
Akt2 and its downstream effectors mediate insulin-stimulated GLUT4-storage vesicle (GSV) translocation and fusion with the plasma membrane (PM). Using mass spectrometry, we identify actin-capping protein Tropomodulin 3 (Tmod3) as an Akt2-interacting partner in 3T3-L1 adipocytes. We demonstrate that Tmod3 is phosphorylated at Ser71 on insulin-stimulated Akt2 activation, and Ser71 phosphorylation is required for insulin-stimulated GLUT4 PM insertion and glucose uptake. Phosphorylated Tmod3 regulates insulin-induced actin remodelling, an essential step for GSV fusion with the PM. Furthermore, the interaction of Tmod3 with its cognate tropomyosin partner, Tm5NM1 is necessary for GSV exocytosis and glucose uptake. Together these results establish Tmod3 as a novel Akt2 effector that mediates insulin-induced cortical actin remodelling and subsequent GLUT4 membrane insertion. Our findings suggest that defects in cytoskeletal remodelling may contribute to impaired GLUT4 exocytosis and glucose uptake.
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45
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Lu Q, Li J, Ye F, Zhang M. Structure of myosin-1c tail bound to calmodulin provides insights into calcium-mediated conformational coupling. Nat Struct Mol Biol 2014; 22:81-8. [PMID: 25437912 DOI: 10.1038/nsmb.2923] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/29/2014] [Indexed: 12/27/2022]
Abstract
Class I myosins can sense cellular mechanical forces and function as tension-sensitive anchors or transporters. How mechanical load is transduced from the membrane-binding tail to the force-generating head in myosin-1 is unknown. Here we determined the crystal structure of the entire tail of mouse myosin-1c in complex with apocalmodulin, showing that myosin-1c adopts a stable monomer conformation suited for force transduction. The lever-arm helix and the C-terminal extended PH domain of the motor are coupled by a stable post-IQ domain bound to calmodulin in a highly unusual mode. Ca(2+) binding to calmodulin induces major conformational changes in both IQ motifs and the post-IQ domain and increases flexibility of the myosin-1c tail. Our study provides a structural blueprint for the neck and tail domains of myosin-1 and expands the target binding modes of the master Ca(2+)-signal regulator calmodulin.
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Affiliation(s)
- Qing Lu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianchao Li
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Fei Ye
- 1] Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. [2] Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- 1] Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. [2] Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. [3] State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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46
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The cultural divide: exponential growth in classical 2D and metabolic equilibrium in 3D environments. PLoS One 2014; 9:e106973. [PMID: 25222612 PMCID: PMC4164521 DOI: 10.1371/journal.pone.0106973] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/04/2014] [Indexed: 01/26/2023] Open
Abstract
INTRODUCTION Cellular metabolism can be considered to have two extremes: one is characterized by exponential growth (in 2D cultures) and the other by a dynamic equilibrium (in 3D cultures). We have analyzed the proteome and cellular architecture at these two extremes and found that they are dramatically different. RESULTS Structurally, actin organization is changed, microtubules are increased and keratins 8 and 18 decreased. Metabolically, glycolysis, fatty acid metabolism and the pentose phosphate shunt are increased while TCA cycle and oxidative phosphorylation is unchanged. Enzymes involved in cholesterol and urea synthesis are increased consistent with the attainment of cholesterol and urea production rates seen in vivo. DNA repair enzymes are increased even though cells are predominantly in Go. Transport around the cell--along the microtubules, through the nuclear pore and in various types of vesicles has been prioritized. There are numerous coherent changes in transcription, splicing, translation, protein folding and degradation. The amount of individual proteins within complexes is shown to be highly coordinated. Typically subunits which initiate a particular function are present in increased amounts compared to other subunits of the same complex. SUMMARY We have previously demonstrated that cells at dynamic equilibrium can match the physiological performance of cells in tissues in vivo. Here we describe the multitude of protein changes necessary to achieve this performance.
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47
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Contreras-Ferrat A, Lavandero S, Jaimovich E, Klip A. Calcium signaling in insulin action on striated muscle. Cell Calcium 2014; 56:390-6. [PMID: 25224502 DOI: 10.1016/j.ceca.2014.08.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 08/24/2014] [Accepted: 08/26/2014] [Indexed: 02/07/2023]
Abstract
Striated muscles (skeletal and cardiac) are major physiological targets of insulin and this hormone triggers complex signaling pathways regulating cell growth and energy metabolism. Insulin increases glucose uptake into muscle cells by stimulating glucose transporter (GLUT4) translocation from intracellular compartments to the cell surface. The canonical insulin-triggered signaling cascade controlling this process is constituted by well-mapped tyrosine, lipid and serine/threonine phosphorylation reactions. In parallel to these signals, recent findings reveal insulin-dependent Ca(2+) mobilization in skeletal muscle cells and cardiomyocytes. Specifically, insulin activates the sarco-endoplasmic reticulum (SER) channels that release Ca(2+) into the cytosol i.e., the Ryanodine Receptor (RyR) and the inositol 1,4,5-triphosphate receptor (IP3R). In skeletal muscle cells, a rapid, insulin-triggered Ca(2+) release occurs through RyR, that is brought about upon S-glutathionylation of cysteine residues in the channel by reactive oxygen species (ROS) produced by the early activation of the NADPH oxidase (NOX2). In cardiomyocytes insulin induces a fast and transient increase in cytoplasmic [Ca(2+)]i trough L-type Ca(2+) channels activation. In both cell types, a relatively slower Ca(2+) release also occurs through IP3R activation, and is required for GLUT4 translocation and glucose uptake. The insulin-dependent Ca(2+) released from IP3R of skeletal muscle also promotes mitochondrial Ca(2+) uptake. We review here these actions of insulin on intracellular Ca(2+) channel activation and their impact on GLUT4 traffic in muscle cells, as well as other implications of insulin-dependent Ca(2+) release from the SER.
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Affiliation(s)
- A Contreras-Ferrat
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile; Advanced Center for Chronic Disease (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences & Faculty of Medicine, Chile; Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago 8380492, Chile.
| | - S Lavandero
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile; Advanced Center for Chronic Disease (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences & Faculty of Medicine, Chile
| | - E Jaimovich
- Center for Molecular Studies of the Cell (CEMC), Faculty of Medicine, Chile
| | - A Klip
- The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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Li Q, Zhu X, Ishikura S, Zhang D, Gao J, Sun Y, Contreras-Ferrat A, Foley KP, Lavandero S, Yao Z, Bilan PJ, Klip A, Niu W. Ca²⁺ signals promote GLUT4 exocytosis and reduce its endocytosis in muscle cells. Am J Physiol Endocrinol Metab 2014; 307:E209-24. [PMID: 24895284 DOI: 10.1152/ajpendo.00045.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Elevating cytosolic Ca(2+) stimulates glucose uptake in skeletal muscle, but how Ca(2+) affects intracellular traffic of GLUT4 is unknown. In tissue, changes in Ca(2+) leading to contraction preclude analysis of the impact of individual, Ca(2+)-derived signals. In L6 muscle cells stably expressing GLUT4myc, the Ca(2+) ionophore ionomycin raised cytosolic Ca(2+) and caused a gain in cell surface GLUT4myc. Extra- and intracellular Ca(2+) chelators (EGTA, BAPTA-AM) reversed this response. Ionomycin activated calcium calmodulin kinase II (CaMKII), AMPK, and PKCs, but not Akt. Silencing CaMKIIδ or AMPKα1/α2 partly reduced the ionomycin-induced gain in surface GLUT4myc, as did peptidic or small molecule inhibitors of CaMKII (CN21) and AMPK (Compound C). Compared with the conventional isoenzyme PKC inhibitor Gö6976, the conventional plus novel PKC inhibitor Gö6983 lowered the ionomycin-induced gain in cell surface GLUT4myc. Ionomycin stimulated GLUT4myc exocytosis and inhibited its endocytosis in live cells. siRNA-mediated knockdown of CaMKIIδ or AMPKα1/α2 partly reversed ionomycin-induced GLUT4myc exocytosis but did not prevent its reduced endocytosis. Compared with Gö6976, Gö6983 markedly reversed the slowing of GLUT4myc endocytosis triggered by ionomycin. In summary, rapid Ca(2+) influx into muscle cells accelerates GLUT4myc exocytosis while slowing GLUT4myc endocytosis. CaMKIIδ and AMPK stimulate GLUT4myc exocytosis, whereas novel PKCs reduce endocytosis. These results identify how Ca(2+)-activated signals selectively regulate GLUT4 exocytosis and endocytosis in muscle cells.
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Affiliation(s)
- Q Li
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - X Zhu
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - S Ishikura
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - D Zhang
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - J Gao
- Clinical Laboratory, First Teaching Hospital of Tianjin University of TCM, Tianjin, China; and
| | - Y Sun
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - A Contreras-Ferrat
- Advanced Center for Chronic Diseases and Center for Molecular Studies of the Cell, Facultad de Ciencias Quimicas y Farmaceuticas/Facultad Medicina; Universidad de Chile; Santiago, Chile
| | - K P Foley
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - S Lavandero
- Advanced Center for Chronic Diseases and Center for Molecular Studies of the Cell, Facultad de Ciencias Quimicas y Farmaceuticas/Facultad Medicina; Universidad de Chile; Santiago, Chile
| | - Z Yao
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - P J Bilan
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - A Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - W Niu
- Department of Immunology, Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital and Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China;
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49
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Klip A, Sun Y, Chiu TT, Foley KP. Signal transduction meets vesicle traffic: the software and hardware of GLUT4 translocation. Am J Physiol Cell Physiol 2014; 306:C879-86. [DOI: 10.1152/ajpcell.00069.2014] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Skeletal muscle is the major tissue disposing of dietary glucose, a function regulated by insulin-elicited signals that impart mobilization of GLUT4 glucose transporters to the plasma membrane. This phenomenon, also central to adipocyte biology, has been the subject of intense and productive research for decades. We focus on muscle cell studies scrutinizing insulin signals and vesicle traffic in a spatiotemporal manner. Using the analogy of an integrated circuit to approach the intersection between signal transduction and vesicle mobilization, we identify signaling relays (“software”) that engage structural/mechanical elements (“hardware”) to enact the rapid mobilization and incorporation of GLUT4 into the cell surface. We emphasize how insulin signal transduction switches from tyrosine through lipid and serine phosphorylation down to activation of small G proteins of the Rab and Rho families, describe key negative regulation step of Rab GTPases through the GTPase-activating protein activity of the Akt substrate of 160 kDa (AS160), and focus on the mechanical effectors engaged by Rabs 8A and 10 (the molecular motor myosin Va), and the Rho GTPase Rac1 (actin filament branching and severing through Arp2/3 and cofilin). Finally, we illustrate how actin filaments interact with myosin 1c and α-Actinin4 to promote vesicle tethering as preamble to fusion with the membrane.
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Affiliation(s)
- Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and
- Department of Biochemistry, The University of Toronto, Ontario, Canada
| | - Yi Sun
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and
| | - Tim Ting Chiu
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and
- Department of Biochemistry, The University of Toronto, Ontario, Canada
| | - Kevin P. Foley
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and
- Department of Biochemistry, The University of Toronto, Ontario, Canada
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Foley KP, Klip A. Dynamic GLUT4 sorting through a syntaxin-6 compartment in muscle cells is derailed by insulin resistance-causing ceramide. Biol Open 2014; 3:314-25. [PMID: 24705014 PMCID: PMC4021353 DOI: 10.1242/bio.20147898] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
GLUT4 constitutively recycles between the plasma membrane and intracellular depots. Insulin shifts this dynamic equilibrium towards the plasma membrane by recruiting GLUT4 to the plasma membrane from insulin-responsive vesicles. Muscle is the primary site for dietary glucose deposition; however, how GLUT4 sorts into insulin-responsive vesicles, and if and how insulin resistance affects this process, is unknown. In L6 myoblasts stably expressing myc-tagged GLUT4, we analyzed the intracellular itinerary of GLUT4 as it internalizes from the cell surface and examined if such sorting is perturbed by C2-ceramide, a lipid metabolite causing insulin resistance. Surface-labeled GLUT4myc that internalized for 30 min accumulated in a Syntaxin-6 (Stx6)- and Stx16-positive perinuclear sub-compartment devoid of furin or internalized transferrin, and displayed insulin-responsive re-exocytosis. C2-ceramide dispersed the Stx6-positive sub-compartment and prevented insulin-responsive re-exocytosis of internalized GLUT4myc, even under conditions not affecting insulin-stimulated signaling towards Akt. Microtubule disruption with nocodazole prevented pre-internalized GLUT4myc from reaching the Stx6-positive perinuclear sub-compartment and from undergoing insulin-responsive exocytosis. Removing nocodazole allowed both parameters to recover, suggesting that the Stx6-positive perinuclear sub-compartment was required for GLUT4 insulin-responsiveness. Accordingly, Stx6 knockdown inhibited by ∼50% the ability of internalized GLUT4myc to undergo insulin-responsive re-exocytosis without altering its overall perinuclear accumulation. We propose that Stx6 defines the insulin-responsive compartment in muscle cells. Our data are consistent with a model where ceramide could cause insulin resistance by altering intracellular GLUT4 sorting.
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Affiliation(s)
- Kevin P Foley
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Amira Klip
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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