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Bi J, Carroll RT, James ML, Ouderkirk JL, Krendel M, Sirotkin V. Effects of FSGS-associated mutations on the stability and function of myosin-1 in fission yeast. Dis Model Mech 2015; 8:891-902. [PMID: 26092123 PMCID: PMC4527290 DOI: 10.1242/dmm.020214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/09/2015] [Indexed: 12/26/2022] Open
Abstract
Point mutations in the human MYO1E gene, encoding class I myosin Myo1e, are associated with focal segmental glomerulosclerosis (FSGS), a primary kidney disorder that leads to end-stage kidney disease. In this study, we used a simple model organism, fission yeast Schizosaccharomyces pombe, to test the effects of FSGS-associated mutations on myosin activity. Fission yeast has only one class I myosin, Myo1, which is involved in actin patch assembly at the sites of endocytosis. The amino acid residues mutated in individuals with FSGS are conserved between human Myo1e and yeast Myo1, which allowed us to introduce equivalent mutations into yeast myosin and use the resulting mutant strains for functional analysis. Yeast strains expressing mutant Myo1 exhibited defects in growth and endocytosis similar to those observed in the myo1 deletion strain. These mutations also disrupted Myo1 localization to endocytic actin patches and resulted in mis-localization of Myo1 to eisosomes, linear membrane microdomains found in yeast cells. Although both mutants examined in this study exhibited loss of function, one of these mutants was also characterized by the decreased protein stability. Thus, using the yeast model system, we were able to determine that the kidney-disease-associated mutations impair myosin functional activity and have differential effects on protein stability. Summary: In the fission yeast S. pombe, kidney disease-associated mutations in Myo1, a homolog of human Myo1e, disrupt myosin localization and function.
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Affiliation(s)
- Jing Bi
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| | - Robert T Carroll
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| | - Michael L James
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| | - Jessica L Ouderkirk
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| | - Mira Krendel
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
| | - Vladimir Sirotkin
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
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52
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Inoue K, Ishibe S. Podocyte endocytosis in the regulation of the glomerular filtration barrier. Am J Physiol Renal Physiol 2015; 309:F398-405. [PMID: 26084928 DOI: 10.1152/ajprenal.00136.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023] Open
Abstract
Severe defects in the glomerular filtration barrier result in nephrotic syndrome, which is characterized by massive proteinuria. The podocyte, a specialized epithelial cell with interdigitating foot processes separated by a slit diaphragm, plays a vital role in regulating the passage of proteins from the capillary lumen to Bowman's space. Recent findings suggest a critical role for endocytosis in podocyte biology as highlighted by genetic mouse models of disease and human genetic mutations that result in the loss of the integrity of the glomerular filtration barrier. In vitro podocyte studies have also unraveled a plethora of constituents that are differentially internalized to maintain homeostasis. These observations provide a framework and impetus for understanding the precise regulation of podocyte endocytic machinery in both health and disease.
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Affiliation(s)
- Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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53
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Maxeiner S, Shi N, Schalla C, Aydin G, Hoss M, Vogel S, Zenke M, Sechi AS. Crucial role for the LSP1-myosin1e bimolecular complex in the regulation of Fcγ receptor-driven phagocytosis. Mol Biol Cell 2015; 26:1652-64. [PMID: 25717183 PMCID: PMC4436777 DOI: 10.1091/mbc.e14-05-1005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 02/19/2015] [Indexed: 01/24/2023] Open
Abstract
The actin cytoskeleton is fundamental for the innate immune process of phagocytosis. This study shows that LSP1 plays a pivotal role in the regulation of actin cytoskeleton remodeling during Fcγ receptor–mediated phagocytosis and that its interactions with myosin1e and actin are crucial for the efficiency of this actin-driven process. Actin cytoskeleton remodeling is fundamental for Fcγ receptor–driven phagocytosis. In this study, we find that the leukocyte-specific protein 1 (LSP1) localizes to nascent phagocytic cups during Fcγ receptor–mediated phagocytosis, where it displays the same spatial and temporal distribution as the actin cytoskeleton. Down-regulation of LSP1 severely reduces the phagocytic activity of macrophages, clearly demonstrating a crucial role for this protein in Fcγ receptor–mediated phagocytosis. We also find that LSP1 binds to the class I molecular motor myosin1e. LSP1 interacts with the SH3 domain of myosin1e, and the localization and dynamics of both proteins in nascent phagocytic cups mirror those of actin. Furthermore, inhibition of LSP1–myosin1e and LSP1–actin interactions profoundly impairs pseudopodial formation around opsonized targets and their subsequent internalization. Thus the LSP1–myosin1e bimolecular complex plays a pivotal role in the regulation of actin cytoskeleton remodeling during Fcγ receptor–driven phagocytosis.
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Affiliation(s)
- Sebastian Maxeiner
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
| | - Nian Shi
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
| | - Carmen Schalla
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
| | - Guelcan Aydin
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
| | - Mareike Hoss
- Electron Microscopy Facility, Uniklinik RWTH Aachen, Applied Ecology, D-52074 Aachen, Germany
| | - Simon Vogel
- Fraunhofer Institute for Molecular Biology and Applied Ecology, D-52074 Aachen, Germany
| | - Martin Zenke
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
| | - Antonio S Sechi
- Institute of Biomedical Engineering, Department of Cell Biology, Applied Ecology, D-52074 Aachen, Germany
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54
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Cortesio CL, Lewellyn EB, Drubin DG. Control of lipid organization and actin assembly during clathrin-mediated endocytosis by the cytoplasmic tail of the rhomboid protein Rbd2. Mol Biol Cell 2015; 26:1509-22. [PMID: 25694450 PMCID: PMC4395130 DOI: 10.1091/mbc.e14-11-1540] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 02/09/2015] [Indexed: 12/13/2022] Open
Abstract
Clathrin-mediated endocytosis (CME) requires precise regulation of the actin cytoskeleton. The yeast rhomboid protein Rbd2 controls the timing of actin polymerization during CME through its cytoplasmic tail and a PtdIns(4,5)P2-dependent mechanism. Clathrin-mediated endocytosis (CME) is facilitated by a precisely regulated burst of actin assembly. PtdIns(4,5)P2 is an important signaling lipid with conserved roles in CME and actin assembly regulation. Rhomboid family multipass transmembrane proteins regulate diverse cellular processes; however, rhomboid-mediated CME regulation has not been described. We report that yeast lacking the rhomboid protein Rbd2 exhibit accelerated endocytic-site dynamics and premature actin assembly during CME through a PtdIns(4,5)P2-dependent mechanism. Combined genetic and biochemical studies showed that the cytoplasmic tail of Rbd2 binds directly to PtdIns(4,5)P2 and is sufficient for Rbd2's role in actin regulation. Analysis of an Rbd2 mutant with diminished PtdIns(4,5)P2-binding capacity indicates that this interaction is necessary for the temporal regulation of actin assembly during CME. The cytoplasmic tail of Rbd2 appears to modulate PtdIns(4,5)P2 distribution on the cell cortex. The syndapin-like F-BAR protein Bzz1 functions in a pathway with Rbd2 to control the timing of type 1 myosin recruitment and actin polymerization onset during CME. This work reveals that the previously unstudied rhomboid protein Rbd2 functions in vivo at the nexus of three highly conserved processes: lipid regulation, endocytic regulation, and cytoskeletal function.
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Affiliation(s)
- Christa L Cortesio
- Department of Molecular- and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Eric B Lewellyn
- Department of Molecular- and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - David G Drubin
- Department of Molecular- and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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55
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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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56
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Wenzel J, Ouderkirk JL, Krendel M, Lang R. Class I myosin Myo1e regulates TLR4-triggered macrophage spreading, chemokine release, and antigen presentation via MHC class II. Eur J Immunol 2014; 45:225-37. [PMID: 25263281 DOI: 10.1002/eji.201444698] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 08/26/2014] [Accepted: 09/24/2014] [Indexed: 12/25/2022]
Abstract
TLR-mediated recognition of microbial danger induces substantial changes in macrophage migration, adherence, and phagocytosis. Recently, we described the LPS-regulated phosphorylation of many cytoskeleton-associated proteins by phosphoproteomics. The functional role of these cytoskeletal and motor proteins in innate immune cell responses is largely unexplored. Here, we first identified both long-tailed class I myosins Myo1e and Myo1f as important contributors to LPS-triggered macrophage spreading. Mouse bone marrow-derived macrophages and DCs deficient in Myo1e selectively secreted increased amounts of the chemokine CCL2. In addition, the cell surface expression of MHC class II (MHC-II) on both cell types was reduced in the absence of Myo1e. However, transcriptional changes in CCL2 and MHC-II were not observed in the absence of Myo1e, indicating that Myo1e regulates specific intracellular transport processes. The capacity of macrophages and DCs lacking Myo1e to stimulate antigen-specific CD4(+) T-cell proliferation was impaired, consistent with the reduced MHC-II surface protein levels. Surprisingly, in Myo1e-deficient DCs, the proteolytic cleavage of endocytosed antigen was also increased. Together, our results provide evidence for a non-redundant function of the motor protein Myo1e in the regulation of TLR4-controlled, cytoskeleton-associated functional properties of macrophages and DCs, and in induction of a full MHC-II-restricted adaptive immune response.
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Affiliation(s)
- Jens Wenzel
- Institute of Clinical Microbiology, Immunology and Hygiene, University Hospital Erlangen, Friedrich Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
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57
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Coudrier E, Almeida CG. Myosin 1 controls membrane shape by coupling F-Actin to membrane. BIOARCHITECTURE 2014; 1:230-235. [PMID: 22754614 PMCID: PMC3384575 DOI: 10.4161/bioa.18406] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cellular functions are intimately associated with rapid changes in membrane shape. Different mechanisms interfering with the lipid bilayer, such as the insertion of proteins with amphipatic helices or the association of a protein scaffold, trigger membrane bending. By exerting force on membranes, molecular motors can also contribute to membrane remodeling. Previous studies have shown that actin and myosin 1 participate in the invagination of the plasma membrane during endocytosis while kinesins and dynein with microtubules provide the force to elongate membrane buds at recycling endosomes and at the trans-Golgi network (TGN). Using live cell imaging we have recently shown that a myosin 1 (myosin 1b) regulates the actin dependent post-Golgi traffic of cargo and generates force that controls the assembly of F-actin foci and promotes with the actin cytoskeleton the formation of tubules at the TGN. Our data provide evidence that actin and myosin 1 can regulate membrane remodeling of organelles as well as having an unexpected role in the spatial organization of the actin cytoskeleton. Here, we discuss our results together with the role of actin and other myosins that have been implicated in the traffic of cargo.
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58
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Ouderkirk JL, Krendel M. Non-muscle myosins in tumor progression, cancer cell invasion, and metastasis. Cytoskeleton (Hoboken) 2014; 71:447-63. [PMID: 25087729 DOI: 10.1002/cm.21187] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 07/28/2014] [Accepted: 07/29/2014] [Indexed: 02/06/2023]
Abstract
The actin cytoskeleton, which regulates cell polarity, adhesion, and migration, can influence cancer progression, including initial acquisition of malignant properties by normal cells, invasion of adjacent tissues, and metastasis to distant sites. Actin-dependent molecular motors, myosins, play key roles in regulating tumor progression and metastasis. In this review, we examine how non-muscle myosins regulate neoplastic transformation and cancer cell migration and invasion. Members of the myosin superfamily can act as either enhancers or suppressors of tumor progression. This review summarizes the current state of knowledge on how mutations or epigenetic changes in myosin genes and changes in myosin expression may affect tumor progression and patient outcomes and discusses the proposed mechanisms linking myosin inactivation or upregulation to malignant phenotype, cancer cell migration, and metastasis.
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Affiliation(s)
- Jessica L Ouderkirk
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, New York
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59
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60
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Flores JA, Balseiro-Gomez S, Cabeza JM, Acosta J, Ramirez-Ponce P, Ales E. A new role for myosin II in vesicle fission. PLoS One 2014; 9:e100757. [PMID: 24959909 PMCID: PMC4069105 DOI: 10.1371/journal.pone.0100757] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022] Open
Abstract
An endocytic vesicle is formed from a flat plasma membrane patch by a sequential process of invagination, bud formation and fission. The scission step requires the formation of a tubular membrane neck (the fission pore) that connects the endocytic vesicle with the plasma membrane. Progress in vesicle fission can be measured by the formation and closure of the fission pore. Live-cell imaging and sensitive biophysical measurements have provided various glimpses into the structure and behaviour of the fission pore. In the present study, the role of non-muscle myosin II (NM-2) in vesicle fission was tested by analyzing the kinetics of the fission pore with perforated-patch clamp capacitance measurements to detect single vesicle endocytosis with millisecond time resolution in peritoneal mast cells. Blebbistatin, a specific inhibitor of NM-2, dramatically increased the duration of the fission pore and also prevented closure during large endocytic events. Using the fluorescent markers FM1-43 and pHrodo Green dextran, we found that NM-2 inhibition greatly arrested vesicle fission in a late phase of the scission event when the pore reached a final diameter of ∼ 5 nm. Our results indicate that loss of the ATPase activity of myosin II drastically reduces the efficiency of membrane scission by making vesicle closure incomplete and suggest that NM-2 might be especially relevant in vesicle fission during compound endocytosis.
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Affiliation(s)
- Juan A. Flores
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Santiago Balseiro-Gomez
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Jose M. Cabeza
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Jorge Acosta
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Pilar Ramirez-Ponce
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
| | - Eva Ales
- Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain
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61
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Granger E, McNee G, Allan V, Woodman P. The role of the cytoskeleton and molecular motors in endosomal dynamics. Semin Cell Dev Biol 2014; 31:20-9. [PMID: 24727350 PMCID: PMC4071412 DOI: 10.1016/j.semcdb.2014.04.011] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/01/2014] [Accepted: 04/03/2014] [Indexed: 12/28/2022]
Abstract
The endocytic pathway is essential for processes that define how cells interact with their environment, including receptor signalling, cell adhesion and migration, pathogen entry, membrane protein turnover and nutrient uptake. The spatial organisation of endocytic trafficking requires motor proteins that tether membranes or transport them along the actin and microtubule cytoskeletons. Microtubules, actin filaments and motor proteins also provide force to deform and assist in the scission of membranes, thereby facilitating endosomal sorting and the generation of transport intermediates.
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Affiliation(s)
- Elizabeth Granger
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Gavin McNee
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Victoria Allan
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
| | - Philip Woodman
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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62
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Dewerchin HL, Desmarets LM, Noppe Y, Nauwynck HJ. Myosins 1 and 6, myosin light chain kinase, actin and microtubules cooperate during antibody-mediated internalisation and trafficking of membrane-expressed viral antigens in feline infectious peritonitis virus infected monocytes. Vet Res 2014; 45:17. [PMID: 24517254 PMCID: PMC3937040 DOI: 10.1186/1297-9716-45-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/29/2014] [Indexed: 12/20/2022] Open
Abstract
Monocytes infected with feline infectious peritonitis virus, a coronavirus, express viral proteins in their plasma membranes. Upon binding of antibodies, these proteins are quickly internalised through a new clathrin- and caveolae-independent internalisation pathway. By doing so, the infected monocytes can escape antibody-dependent cell lysis. In the present study, we investigated which kinases and cytoskeletal proteins are of importance during internalisation and subsequent intracellular transport. The experiments showed that myosin light chain kinase (MLCK) and myosin 1 are crucial for the initiation of the internalisation. With co-localisation stainings, it was found that MLCK and myosin 1 co-localise with antigens even before internalisation started. Myosin 6 co-localised with the internalising complexes during passage through the cortical actin, were it might play a role in moving or disintegrating actin filaments, to overcome the actin barrier. One minute after internalisation started, vesicles had passed the cortical actin, co-localised with microtubules and association with myosin 6 was lost. The vesicles were further transported over the microtubules and accumulated at the microtubule organising centre after 10 to 30 min. Intracellular trafficking over microtubules was mediated by MLCK, myosin 1 and a small actin tail. Since inhibiting MLCK with ML-7 was so efficient in blocking the internalisation pathway, this target can be used for the development of a new treatment for FIPV.
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Affiliation(s)
| | | | | | - Hans J Nauwynck
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
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63
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Bi J, Pellenz CD, Krendel M. Visualization of cytoskeletal dynamics in podocytes using adenoviral vectors. Cytoskeleton (Hoboken) 2014; 71:145-56. [PMID: 24415679 DOI: 10.1002/cm.21162] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/03/2014] [Indexed: 02/01/2023]
Abstract
Glomerular visceral epithelial cells (podocytes) play a key role in maintaining selective protein filtration in the kidney. Podocytes have a complex cell shape characterized by the presence of numerous actin-rich processes, which cover the surface of glomerular capillaries and are connected by specialized cell-cell adhesion complexes (slit diaphragms). Human genetic studies and experiments in knockout mouse models show that actin filaments and actin-associated proteins are indispensable for the maintenance of podocyte shape, slit diaphragm integrity, and normal glomerular filtration. The ability to examine cytoskeletal protein organization and dynamics in podocytes and to test the effects of disease-associated mutations on protein localization provides valuable information for researchers aiming to dissect the molecular mechanisms of podocyte dysfunction. We describe how adenovirus-mediated transduction of cultured podocytes with DNA constructs can be used to reliably introduce fluorescently tagged cytoskeletal markers for live cell imaging with high efficiency and low toxicity. This technique can be used to study the dynamic reorganization of the podocyte cytoskeleton and to test the effects of novel mutations on podocyte cytoskeletal dynamics.
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Affiliation(s)
- Jing Bi
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York
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64
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Ouderkirk JL, Krendel M. Myosin 1e is a component of the invadosome core that contributes to regulation of invadosome dynamics. Exp Cell Res 2014; 322:265-76. [PMID: 24462457 DOI: 10.1016/j.yexcr.2014.01.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 01/09/2014] [Accepted: 01/15/2014] [Indexed: 01/07/2023]
Abstract
Myosin 1e (myo1e) is an actin-based motor protein that has been implicated in cell adhesion and migration. We examined the role of myo1e in invadosomes, actin-rich adhesion structures that are important for degradation and invasion of the extracellular matrix. RSV-transformed BHK-21 cells, which readily form invadosomes and invadosome rosettes, were used as the experimental model. Myo1e localization to the actin-rich core of invadosomes required the proline-rich Tail Homology 2 (TH2) domain. During invadosome rosette expansion, we observed myo1e recruitment to newly forming invadosomes via Tail Homology 1 (TH1)-dependent interactions with the plasma membrane, where it preceded actin and paxillin. Dominant-negative inhibition of myo1e resulted in mislocalized invadosome formation, usually at the center of the rosette. We propose that TH2 domain of myo1e provides the key signal for localization to invadosomes, while TH1 domain interactions facilitate myo1e targeting to the plasma membrane-proximal locations within the rosettes. Myo1e may then act as a scaffold, linking the plasma membrane with the actin cytoskeleton and helping direct new invadosome formation to the periphery of the rosette.
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Affiliation(s)
- Jessica L Ouderkirk
- Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY 13210, United States
| | - Mira Krendel
- Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY 13210, United States.
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65
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Lennon R, Randles MJ, Humphries MJ. The importance of podocyte adhesion for a healthy glomerulus. Front Endocrinol (Lausanne) 2014; 5:160. [PMID: 25352829 PMCID: PMC4196579 DOI: 10.3389/fendo.2014.00160] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/21/2014] [Indexed: 12/23/2022] Open
Abstract
Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. Unique cell junctions, known as slit diaphragms, which feature nephrin and Neph family proteins in addition to components of adherens, tight, and gap junctions, connect adjacent podocyte foot processes. Single gene disorders affecting the slit diaphragm result in nephrotic syndrome in humans, characterized by massive loss of protein across the capillary wall. In addition to specialized cell junctions, interconnecting podocytes also adhere to the glomerular basement membrane (GBM) of the capillary wall. The GBM is a dense network of secreted, extracellular matrix (ECM) components and contains tissue-restricted isoforms of collagen IV and laminin in addition to other structural proteins and ECM regulators such as proteases and growth factors. The specialized niche of the GBM provides a scaffold for endothelial cells and podocytes to support their unique functions and human genetic mutations in GBM components lead to renal failure, thus highlighting the importance of cell-matrix interactions in the glomerulus. Cells adhere to ECM via adhesion receptors, including integrins, syndecans, and dystroglycan and in particular the integrin heterodimer α3β1 is required to maintain barrier integrity. Therefore, the sophisticated function of glomerular filtration relies on podocyte adhesion both at cell junctions and at the interface with the ECM. In health, the podocyte coordinates signals from cell junctions and cell-matrix interactions, in response to environmental cues in order to regulate filtration and as our understanding of mechanisms that control cell adhesion in the glomerulus develops, then insight into the effects of disease will improve. The ultimate goal will be to develop targeted therapies to prevent or repair defects in the filtration barrier and to restore glomerular function.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
- Department of Paediatric Nephrology, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
- *Correspondence: Rachel Lennon, Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Michael Smith Building, Manchester M13 9PT, UK e-mail:
| | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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Gupta P, Gauthier NC, Cheng-Han Y, Zuanning Y, Pontes B, Ohmstede M, Martin R, Knölker HJ, Döbereiner HG, Krendel M, Sheetz M. Myosin 1E localizes to actin polymerization sites in lamellipodia, affecting actin dynamics and adhesion formation. Biol Open 2013; 2:1288-99. [PMID: 24337113 PMCID: PMC3863413 DOI: 10.1242/bio.20135827] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Because the actin network in active lamellipodia is continuously assembling at the edge, moving inward and disassembling, there is a question as to how actin-binding proteins and other components are transported to the leading edge and how nascent adhesions are stabilized. Active transport could play a significant role in these functions but the components involved are unknown. We show here that Myosin 1E (a long tailed Myosin 1 isoform) rapidly moves to the tips of active lamellipodia and to actin-rich early adhesions, unlike Myosin 1G, 1B or 1C (short tailed isoforms). Myosin 1E co-localizes with CARMIL, FHOD1, Arp3 and β3-integrin in those early adhesions. But these structures precede stable paxillin-rich adhesions. Myosin 1E movement depends upon actin-binding domains and the presence of an SH3 oligomerization domain. Overexpression of a Myosin 1E deletion mutant without the extreme C-terminal interacting (SH3) domain (Myosin 1EΔSH3) increases edge fluctuations and decreases stable adhesion lifetimes. In contrast, overexpression of Myosin 1E full tail domain (TH1+TH2+TH3/SH3) decreases edge fluctuation. In Myosin 1E knockdown cells, and more prominently in cells treated with Myosin 1 inhibitor, cell-matrix adhesions are also short-lived and fail to mature. We suggest that, by moving to actin polymerization sites and early adhesion sites in active lamellipodia, Myosin 1E might play important roles in transporting not only important polymerizing proteins but also proteins involved in adhesion stabilization.
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Affiliation(s)
- Prabuddha Gupta
- Mechanobiology Institute, National University of Singapore, Singapore 117411
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67
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Abstract
PURPOSE OF REVIEW In this review, we discuss the role of endocytosis, a fundamental process internalizing molecules from the plasma membrane, and its critical importance in podocyte biology. RECENT FINDINGS Endocytic clathrin and nonclathrin-coated pits have been visualized in podocytes using electron microscopy, but the functional biological relevance has not been well defined. Recent evidence suggests that loss of key clathrin endocytic regulatory apparatus, such as dynamin, synaptojanin 1 or endophilin, in genetic mouse models of disease results in severe proteinuria and foot process effacement. In addition, several genes implicated in human nephrotic syndrome directly or indirectly associate with these endocytic proteins, thus creating a protein network that is linked in actin dynamics, signalling and endocytosis. SUMMARY This review summarizes our current understanding of membrane trafficking specifically in podocytes, thus giving further novel insights into the molecular mechanisms and pathogenesis of nephrotic syndrome.
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Affiliation(s)
- Keita Soda
- Department of Internal Medicine, Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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68
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Bi J, Chase SE, Pellenz CD, Kurihara H, Fanning AS, Krendel M. Myosin 1e is a component of the glomerular slit diaphragm complex that regulates actin reorganization during cell-cell contact formation in podocytes. Am J Physiol Renal Physiol 2013; 305:F532-44. [PMID: 23761676 DOI: 10.1152/ajprenal.00223.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glomerular visceral epithelial cells, also known as podocytes, are critical to both normal kidney function and the development of kidney disease. Podocyte actin cytoskeleton and their highly specialized cell-cell junctions (also called slit diaphragm complexes) play key roles in controlling glomerular filtration. Myosin 1e (myo1e) is an actin-based molecular motor that is expressed in renal glomeruli. Disruption of the Myo1e gene in mice and humans promotes podocyte injury and results in the loss of the integrity of the glomerular filtration barrier. Here, we have used biochemical and microscopic approaches to determine whether myo1e is associated with the slit diaphragm complexes in glomerular podocytes. Myo1e was consistently enriched in the slit diaphragm fraction during subcellular fractionation of renal glomeruli and colocalized with the slit diaphragm markers in mouse kidney. Live cell imaging studies showed that myo1e was recruited to the newly formed cell-cell junctions in cultured podocytes, where it colocalized with the actin filament cables aligned with the nascent contacts. Myo1e-null podocytes expressing FSGS-associated myo1e mutant (A159P) did not efficiently assemble actin cables along new cell-cell junctions. We have mapped domains in myo1e that were critical for its localization to cell-cell junctions and determined that the SH3 domain of myo1e tail interacts with ZO-1, a component of the slit diaphragm complex and tight junctions. These findings suggest that myo1e represents a component of the slit diaphragm complex and may contribute to regulating junctional integrity in kidney podocytes.
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Affiliation(s)
- J Bi
- Dept. of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210.
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69
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Arif E, Kumari B, Wagner MC, Zhou W, Holzman LB, Nihalani D. Myo1c is an unconventional myosin required for zebrafish glomerular development. Kidney Int 2013; 84:1154-65. [PMID: 23715127 PMCID: PMC3844053 DOI: 10.1038/ki.2013.201] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 03/14/2013] [Accepted: 03/21/2013] [Indexed: 12/17/2022]
Abstract
The targeting and organization of podocyte slit diaphragm proteins nephrin and neph1 is critical for development and maintenance of a functional glomerular filtration barrier. Myo1c is a non-muscle myosin motor protein that interacts directly with nephrin and neph1 and mediates their intracellular transport to the podocyte intercellular junction. Here we investigated the necessity of Myo1c in podocyte development using zebrafish as a model system. Immunofluorescence microscopy and in situ RNA hybridization analysis of zebrafish embryos showed that Myo1c is widely expressed in various tissues including the zebrafish glomerulus. Knockdown of the Myo1c gene in zebrafish using antisense morpholino derivatives resulted in an abnormal developmental phenotype that included pericardial edema and dilated renal tubules. Ultra-structural analysis of the glomerulus in Myo1c depleted zebrafish showed abnormal podocyte morphology and absence of the slit diaphragm. Consistent with these observations, the glomerular filter permeability appeared altered in zebrafish in which Myo1c expression was attenuated. The specificity of Myo1c knockdown was confirmed by a rescue experiment in which co-injection of Myo1c morpholino derivatives with orthologous Myo1c mRNA prepared from mouse cDNA lessened phenotypic abnormalities including edema in Myo1c morphants. Thus, our results demonstrate that Myo1c is necessary for podocyte morphogenesis.
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Affiliation(s)
- Ehtesham Arif
- Renal Electrolyte and Hypertension Division, Perlman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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70
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Hsu F, Mao Y. The Sac domain-containing phosphoinositide phosphatases: structure, function, and disease. ACTA ACUST UNITED AC 2013; 8:395-407. [PMID: 24860601 DOI: 10.1007/s11515-013-1258-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Phosphoinositides (PIs) have long been known to have an essential role in cell physiology. Their intracellular localization and concentration must be tightly regulated for their proper function. This spatial and temporal regulation is achieved by a large number of PI kinases and phosphatases that are present throughout eukaryotic species. One family of these enzymes contains a conserved PI phosphatase domain termed Sac. Although the Sac domain is homologous among different Sac domain-containing proteins, all appear to exhibit varied substrate specificity and subcellular localization. Dysfunctions in several members of this family are implicated in a range of human diseases such as cardiac hypertrophy, bipolar disorder, Down's syndrome, Charcot-Marie-Tooth disease (CMT) and Amyotrophic Lateral Sclerosis (ALS). In plant, several Sac domain-containing proteins have been implicated in the stress response, chloroplast function and polarized secretion. In this review, we focus on recent findings in the family of Sac domain-containing PI phosphatases in yeast, mammal and plant, including the structural analysis into the mechanism of enzymatic activity, cellular functions, and their roles in disease pathophysiology.
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Affiliation(s)
- FoSheng Hsu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Yuxin Mao
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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71
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Affiliation(s)
- M Amanda Hartman
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
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72
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Greenberg MJ, Ostap EM. Regulation and control of myosin-I by the motor and light chain-binding domains. Trends Cell Biol 2012. [PMID: 23200340 DOI: 10.1016/j.tcb.2012.10.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Members of the myosin-I family of molecular motors are expressed in many eukaryotes, where they are involved in a multitude of critical processes. Humans express eight distinct members of the myosin-I family, making it the second largest family of myosins expressed in humans. Despite the high degree of sequence conservation in the motor and light chain-binding domains (LCBDs) of these myosins, recent studies have revealed surprising diversity of function and regulation arising from isoform-specific differences in these domains. Here we review the regulation of myosin-I function and localization by the motor and LCBDs.
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Affiliation(s)
- Michael J Greenberg
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
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73
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Soda K, Balkin DM, Ferguson SM, Paradise S, Milosevic I, Giovedi S, Volpicelli-Daley L, Tian X, Wu Y, Ma H, Son SH, Zheng R, Moeckel G, Cremona O, Holzman LB, De Camilli P, Ishibe S. Role of dynamin, synaptojanin, and endophilin in podocyte foot processes. J Clin Invest 2012. [PMID: 23187129 DOI: 10.1172/jci65289] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Podocytes are specialized cells that play an integral role in the renal glomerular filtration barrier via their foot processes. The foot processes form a highly organized structure, the disruption of which causes nephrotic syndrome. Interestingly, several similarities have been observed between mechanisms that govern podocyte organization and mechanisms that mediate neuronal synapse development. Dynamin, synaptojanin, and endophilin are functional partners in synaptic vesicle recycling via interconnected actions in clathrin-mediated endocytosis and actin dynamics in neurons. A role of dynamin in the maintenance of the kidney filtration barrier via an action on the actin cytoskeleton of podocytes was suggested. Here we used a conditional double-KO of dynamin 1 (Dnm1) and Dnm2 in mouse podocytes to confirm dynamin's role in podocyte foot process maintenance. In addition, we demonstrated that while synaptojanin 1 (Synj1) KO mice and endophilin 1 (Sh3gl2), endophilin 2 (Sh3gl1), and endophilin 3 (Sh3gl3) triple-KO mice had grossly normal embryonic development, these mutants failed to establish a normal filtration barrier and exhibited severe proteinuria due to abnormal podocyte foot process formation. These results strongly implicate a protein network that functions at the interface between endocytosis and actin at neuronal synapses in the formation and maintenance of the kidney glomerular filtration barrier.
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Affiliation(s)
- Keita Soda
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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74
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Abstract
Endocytosis includes a number of processes by which cells internalize segments of their plasma membrane, enclosing a wide variety of material from outside the cell. Endocytosis can contribute to uptake of nutrients, regulation of signaling molecules, control of osmotic pressure, and function of synapses. The actin cytoskeleton plays an essential role in several of these processes. Actin assembly can create protrusions that encompass extracellular materials. Actin can also support the processes of invagination of a membrane segment into the cytoplasm, elongation of the invagination, scission of the new vesicle from the plasma membrane, and movement of the vesicle away from the membrane. We briefly discuss various types of endocytosis, including phagocytosis, macropinocytosis, and clathrin-independent endocytosis. We focus mainly on new findings on the relative importance of actin in clathrin-mediated endocytosis (CME) in yeast versus mammalian cells.
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Affiliation(s)
- Olivia L Mooren
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
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75
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Cheng J, Grassart A, Drubin DG. Myosin 1E coordinates actin assembly and cargo trafficking during clathrin-mediated endocytosis. Mol Biol Cell 2012; 23:2891-904. [PMID: 22675027 PMCID: PMC3408416 DOI: 10.1091/mbc.e11-04-0383] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
An actin-dependent role is shown for Myo1E in the trafficking of newly internalized cargo to early endosomes during CME. The results establish for mammalian cells, similar to budding yeast, interdependence in the recruitment of type I myosins, WIP/WIRE, and N-WASP to endocytic sites to assemble F-actin as endocytic vesicles are being formed. Myosin 1E (Myo1E) is recruited to sites of clathrin-mediated endocytosis coincident with a burst of actin assembly. The recruitment dynamics and lifetime of Myo1E are similar to those of tagged actin polymerization regulatory proteins. Like inhibition of actin assembly, depletion of Myo1E causes reduced transferrin endocytosis and a significant delay in transferrin trafficking to perinuclear compartments, demonstrating an integral role for Myo1E in these actin-mediated steps. Mistargeting of GFP-Myo1E or its src-homology 3 domain to mitochondria results in appearance of WIP, WIRE, N-WASP, and actin filaments at the mitochondria, providing evidence for Myo1E's role in actin assembly regulation. These results suggest for mammalian cells, similar to budding yeast, interdependence in the recruitment of type I myosins, WIP/WIRE, and N-WASP to endocytic sites for Arp2/3 complex activation to assemble F-actin as endocytic vesicles are being formed.
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Affiliation(s)
- Jackie Cheng
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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76
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Chandhoke SK, Mooseker MS. A role for myosin IXb, a motor-RhoGAP chimera, in epithelial wound healing and tight junction regulation. Mol Biol Cell 2012; 23:2468-80. [PMID: 22573889 PMCID: PMC3386211 DOI: 10.1091/mbc.e11-09-0803] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Myo9b is a motor–RhoGAP chimera that has been implicated in inflammatory bowel disease. Findings suggest that Myo9b is essential during both collective and individual wound-induced cell migration. It is also important for maintaining tight junction barrier integrity. Polymorphisms in the gene encoding the heavy chain of myosin IXb (Myo9b) have been linked to several forms of inflammatory bowel disease (IBD). Given that Myo9b contains a RhoGTPase-activating protein domain within its tail, it may play key roles in Rho-mediated actin cytoskeletal modifications critical to intestinal barrier function. In wounded monolayers of the intestinal epithelial cell line Caco2BBe (BBe), Myo9b localizes to the extreme leading edge of lamellipodia of migrating cells. BBe cells exhibiting loss of Myo9b expression with RNA interference or Myo9b C-terminal dominant-negative (DN) tail-tip expression lack lamellipodia, fail to migrate into the wound, and form stress fiber–like arrays of actin at the free edges of cells facing the wound. These cells also exhibit disruption of tight junction (TJ) protein localization, including ZO-1, occludin, and claudin-1. Torsional motility and junctional permeability to dextran are greatly increased in cells expressing DN-tail-tip. Of interest, this effect is propagated to neighboring cells. Consistent with a role for Myo9b in regulating levels of active Rho, localization of both RhoGTP and myosin light chain phosphorylation corresponds to Myo9b-knockdown regions of BBe monolayers. These data reveal critical roles for Myo9b during epithelial wound healing and maintenance of TJ integrity—key functions that may be altered in patients with Myo9b-linked IBD.
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Affiliation(s)
- Surjit K Chandhoke
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
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77
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Kravtsov DV, Caputo C, Collaco A, Hoekstra N, Egan ME, Mooseker MS, Ameen NA. Myosin Ia is required for CFTR brush border membrane trafficking and ion transport in the mouse small intestine. Traffic 2012; 13:1072-82. [PMID: 22510086 DOI: 10.1111/j.1600-0854.2012.01368.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 04/12/2012] [Accepted: 04/17/2012] [Indexed: 12/16/2022]
Abstract
In enterocytes of the small intestine, endocytic trafficking of CFTR channels from the brush border membrane (BBM) to the subapical endosomes requires the minus-end motor, myosin VI (Myo6). The subapical localization of Myo6 is dependent on myosin Ia (Myo1a) the major plus-end motor associated with the BBM, suggestive of functional synergy between these two motors. In villus enterocytes of the Myo1a KO mouse small intestine, CFTR accumulated in syntaxin-3 positive subapical endosomes, redistributed to the basolateral domain and was absent from the BBM. In colon, where villi are absent and Myo1a expression is low, CFTR exhibited normal localization to the BBM in the Myo1a KO similar to WT. cAMP-stimulated CFTR anion transport in the small intestine was reduced by 58% in the KO, while anion transport in the colon was comparable to WT. Co-immunoprecipitation confirmed the association of CFTR with Myo1a. These data indicate that Myo1a is an important regulator of CFTR traffic and anion transport in the BBM of villus enterocytes and suggest that Myo1a may power apical CFTR movement into the BBM from subapical endosomes. Alternatively, it may anchor CFTR channels in the BBM of villus enterocytes as was proposed for Myo1a's role in BBM localization of sucrase-isomaltase.
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Affiliation(s)
- Dmitri V Kravtsov
- Department of Pediatrics/Gastroenterology & Hepatology, Yale University School of Medicine, 333 Cedar Street, FMP 408, P.O. Box 208064, New Haven, CT 06520, USA
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78
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Abstract
Proteinuria is often accompanied by a pathological change in the glomerulus that is refereed as effacement of the podocyte foot processes. The highly dynamic podocyte foot processes contain an actin-based contractile apparatus comparable to that of pericytes, which needs to be precisely and temporally controlled to withstand high pressure in the capillaries and to maintain intact glomerular filtration properties. This review outlines the most recent concepts on the function of the podocyte contractile apparatus with a focus on the role of non-muscle myosins as they have been highlighted by studies in monogenic hereditary proteinuric diseases.
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Affiliation(s)
- Marina Noris
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases "Aldo e Cele Daccò", Department of Molecular Medicine, Ranica, Italy
| | - Giuseppe Remuzzi
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy.,Unit of Nephrology and Dialysis, Azienda Ospedaliera, Ospedali Riuniti di Bergamo, Italy
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79
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Garg P, Holzman LB. Podocytes: gaining a foothold. Exp Cell Res 2012; 318:955-63. [PMID: 22421512 DOI: 10.1016/j.yexcr.2012.02.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 02/24/2012] [Indexed: 01/29/2023]
Abstract
In an attempt to understand the basis of glomerular disease, significant progress has been made in understanding the mechanisms that determine podocyte development and the maintenance of podocyte health. This review examines recent advances in this area focusing on the podocyte intercellular junction, actin cytoskeletal dynamics, and determinants of podocyte cell polarity, autophagy and mTOR biology.
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Affiliation(s)
- Puneet Garg
- Division of Nephrology, University of Michigan, Ann Arbor, MI, USA
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80
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Hegan PS, Giral H, Levi M, Mooseker MS. Myosin VI is required for maintenance of brush border structure, composition, and membrane trafficking functions in the intestinal epithelial cell. Cytoskeleton (Hoboken) 2012; 69:235-51. [PMID: 22328452 DOI: 10.1002/cm.21018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 01/26/2012] [Accepted: 02/06/2012] [Indexed: 12/11/2022]
Abstract
Characterization of the intestinal epithelium of the Snell's waltzer (sv/sv) mouse revealed that myosin VI (Myo6) is required for proper brush border (BB) ultrastructure, composition and membrane traffic. The defects observed were distinct from that observed in the myosin Ia KO, even though Myo6 is lost from the BB in this KO. Myo6 is expressed throughout the length of the small and large intestine; it is localized to the subapical inter-microvillar (MV) domain and basolateral membrane. Defects in the BB include apparent lifting of the plasma membrane off of the actin cytoskeleton in the inter-MV region, fusion of MV, and disorganized morphology of the terminal web. The molecular composition of the sv/sv BB is altered. This includes increased expression of myosin Va, myosin Ie and the MV actin binding proteins espin and phosphorylated-ezrin; myosin Id is reduced. Changes in endocytic components include reduced clathrin and adaptin β, and increased disabled-2. Endocytic uptake of lumenal lactoferrin is inhibited in adult, but not neonatal intestinal epithelial cells. There is increased BB membrane-associated expression of both the Na(+)/H(+) exchanger, NHE3 and the Na(+)/phosphate transporter, NaPi2b. These results suggest that Myo6 is involved in the regulated trafficking of NHE3 and NaPi2b between the BB membrane and endosome.
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Affiliation(s)
- Peter S Hegan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
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81
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Brzeska H, Guag J, Preston GM, Titus MA, Korn ED. Molecular basis of dynamic relocalization of Dictyostelium myosin IB. J Biol Chem 2012; 287:14923-36. [PMID: 22367211 DOI: 10.1074/jbc.m111.318667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Class I myosins have a single heavy chain comprising an N-terminal motor domain with actin-activated ATPase activity and a C-terminal globular tail with a basic region that binds to acidic phospholipids. These myosins contribute to the formation of actin-rich protrusions such as pseudopodia, but regulation of the dynamic localization to these structures is not understood. Previously, we found that Acanthamoeba myosin IC binds to acidic phospholipids in vitro through a short sequence of basic and hydrophobic amino acids, BH site, based on the charge density of the phospholipids. The tail of Dictyostelium myosin IB (DMIB) also contains a BH site. We now report that the BH site is essential for DMIB binding to the plasma membrane and describe the molecular basis of the dynamic relocalization of DMIB in live cells. Endogenous DMIB is localized uniformly on the plasma membrane of resting cells, at active protrusions and cell-cell contacts of randomly moving cells, and at the front of motile polarized cells. The BH site is required for association of DMIB with the plasma membrane at all stages where it colocalizes with phosphoinositide bisphosphate/phosphoinositide trisphosphate (PIP(2)/PIP(3)). The charge-based specificity of the BH site allows for in vivo specificity of DMIB for PIP(2)/PIP(3) similar to the PH domain-based specificity of other class I myosins. However, DMIB-head is required for relocalization of DMIB to the front of migrating cells. Motor activity is not essential, but the actin binding site in the head is important. Thus, dynamic relocalization of DMIB is determined principally by the local PIP(2)/PIP(3) concentration in the plasma membrane and cytoplasmic F-actin.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
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82
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Dyson JM, Fedele CG, Davies EM, Becanovic J, Mitchell CA. Phosphoinositide phosphatases: just as important as the kinases. Subcell Biochem 2012; 58:215-279. [PMID: 22403078 DOI: 10.1007/978-94-007-3012-0_7] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phosphoinositide phosphatases comprise several large enzyme families with over 35 mammalian enzymes identified to date that degrade many phosphoinositide signals. Growth factor or insulin stimulation activates the phosphoinositide 3-kinase that phosphorylates phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] to form phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)], which is rapidly dephosphorylated either by PTEN (phosphatase and tensin homologue deleted on chromosome 10) to PtdIns(4,5)P(2), or by the 5-phosphatases (inositol polyphosphate 5-phosphatases), generating PtdIns(3,4)P(2). 5-phosphatases also hydrolyze PtdIns(4,5)P(2) forming PtdIns(4)P. Ten mammalian 5-phosphatases have been identified, which regulate hematopoietic cell proliferation, synaptic vesicle recycling, insulin signaling, and embryonic development. Two 5-phosphatase genes, OCRL and INPP5E are mutated in Lowe and Joubert syndrome respectively. SHIP [SH2 (Src homology 2)-domain inositol phosphatase] 2, and SKIP (skeletal muscle- and kidney-enriched inositol phosphatase) negatively regulate insulin signaling and glucose homeostasis. SHIP2 polymorphisms are associated with a predisposition to insulin resistance. SHIP1 controls hematopoietic cell proliferation and is mutated in some leukemias. The inositol polyphosphate 4-phosphatases, INPP4A and INPP4B degrade PtdIns(3,4)P(2) to PtdIns(3)P and regulate neuroexcitatory cell death, or act as a tumor suppressor in breast cancer respectively. The Sac phosphatases degrade multiple phosphoinositides, such as PtdIns(3)P, PtdIns(4)P, PtdIns(5)P and PtdIns(3,5)P(2) to form PtdIns. Mutation in the Sac phosphatase gene, FIG4, leads to a degenerative neuropathy. Therefore the phosphatases, like the lipid kinases, play major roles in regulating cellular functions and their mutation or altered expression leads to many human diseases.
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Affiliation(s)
- Jennifer M Dyson
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, 3800, Clayton, Australia
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83
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Anitei M, Hoflack B. Bridging membrane and cytoskeleton dynamics in the secretory and endocytic pathways. Nat Cell Biol 2011; 14:11-9. [PMID: 22193159 DOI: 10.1038/ncb2409] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Transport carriers regulate membrane flow between compartments of the secretory and endocytic pathways in eukaryotic cells. Carrier biogenesis is assisted by microtubules, actin filaments and their associated motors that link to membrane-associated coats, adaptors and accessory proteins. We summarize here how the biochemical properties of membranes inform their interactions with cytoskeletal regulators. We also discuss how the forces generated by the cytoskeleton and motor proteins alter the biophysical properties and the shape of membranes. The interplay between the cytoskeleton and membrane proteins ensures tight spatial and temporal control of carrier biogenesis, which is essential for cellular homeostasis.
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Affiliation(s)
- Mihaela Anitei
- Biotechnology Centre, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
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84
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Abstract
High-resolution structural analysis of branched actin networks at the sites of clathrin-mediated endocytosis sheds light on the role of actin in endocytosis and mechanisms controlling actin assembly.
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Affiliation(s)
- Vladimir Sirotkin
- Department of Cell and Developmental Biology, State University of New York (SUNY) Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210, USA.
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85
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Yang JD, Seol SY, Leem SH, Kim YH, Sun Z, Lee JS, Thorgeirsson SS, Chu IS, Roberts LR, Kang KJ. Genes associated with recurrence of hepatocellular carcinoma: integrated analysis by gene expression and methylation profiling. J Korean Med Sci 2011; 26:1428-38. [PMID: 22065898 PMCID: PMC3207045 DOI: 10.3346/jkms.2011.26.11.1428] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Accepted: 09/06/2011] [Indexed: 12/28/2022] Open
Abstract
Gene expression is suppressed by DNA methylation. The goal of this study was to identify genes whose CpG site methylation and mRNA expression are associated with recurrence after surgical resection for hepatocellular carcinoma (HCC). Sixty-two HCCs were examined by both whole genome DNA methylation and transcriptome analysis. The Cox model was used to select genes associated with recurrence. A validation was performed in an independent cohort of 66 HCC patients. Among fifty-nine common genes, increased CpG site methylation and decreased mRNA expression were associated with recurrence for 12 genes (Group A), whereas decreased CpG site methylation and increased mRNA expression were associated with recurrence for 25 genes (Group B). The remaining 22 genes were defined as Group C. Complement factor H (CFH) and myosin VIIA and Rab interacting protein (MYRIP) in Group A; proline/serine-rich coiled-coil 1 (PSRC1), meiotic recombination 11 homolog A (MRE11A), and myosin IE (MYO1E) in Group B; and autophagy-related protein LC3 A (MAP1LC3A), and NADH dehydrogenase 1 alpha subcomplex assembly factor 1 (NDUFAF1) in Group C were validated. In conclusion, potential tumor suppressor (CFH, MYRIP) and oncogenes (PSRC1, MRE11A, MYO1E) in HCC are reported. The regulation of individual genes by methylation in hepatocarcinogenesis needs to be validated.
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Affiliation(s)
- Ju Dong Yang
- Miles and Shirley Fiterman Center for Digestive Diseases, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - So-Young Seol
- Department of Biological Sciences, Dong-A University, Busan, Korea
| | - Sun-Hee Leem
- Department of Biological Sciences, Dong-A University, Busan, Korea
| | - Yong Hoon Kim
- Department of Surgery, Keimyung University School of Medicine, Daegu, Korea
| | - Zhifu Sun
- Division of Biomedical Statistics and Informatics, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Ju-Seog Lee
- Department of Systems Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX, USA
| | | | - In-Sun Chu
- Korean Bioinformation Center, Korea Research Institute of Bioscience & Biotechnology, Daejeon, Korea
| | - Lewis R. Roberts
- Miles and Shirley Fiterman Center for Digestive Diseases, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Koo Jeong Kang
- Miles and Shirley Fiterman Center for Digestive Diseases, College of Medicine, Mayo Clinic, Rochester, MN, USA
- Department of Surgery, Keimyung University School of Medicine, Daegu, Korea
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86
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Gopaldass N, Patel D, Kratzke R, Dieckmann R, Hausherr S, Hagedorn M, Monroy R, Krüger J, Neuhaus EM, Hoffmann E, Hille K, Kuznetsov SA, Soldati T. Dynamin A, Myosin IB and Abp1 couple phagosome maturation to F-actin binding. Traffic 2011; 13:120-30. [PMID: 22008230 DOI: 10.1111/j.1600-0854.2011.01296.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The role of actin, class I myosins and dynamin in endocytic uptake processes is well characterized, but their role during endo-phagosomal membrane trafficking and maturation is less clear. In Dictyostelium, knockout of myosin IB (myoB) leads to a defect in membrane protein recycling from endosomes back to the plasma membrane. Here, we show that actin plays a central role in the morphology and function of the endocytic pathway. Indeed, latrunculin B (LatB) induces endosome tubulation, a phenotype also observed in dynamin A (dymA)-null cells. Knockout of dymA impairs phagosome acidification, whereas knockout of myoB delays reneutralization, a phenotype mimicked by a low dose of LatB. As a read out for actin-dependent processes during maturation, we monitored the capacity of purified phagosomes to bind F-actin in vitro, and correlated this with the presence of actin-binding and membrane-trafficking proteins. Phagosomes isolated from myoB-null cells showed an increased binding to F-actin, especially late phagosomes. In contrast, early phagosomes from dymA-null cells showed reduced binding to F-actin while late phagosomes were unaffected. We provide evidence that Abp1 is the main F-actin-binding protein in this assay and is central for the interplay between DymA and MyoB during phagosome maturation.
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Affiliation(s)
- Navin Gopaldass
- Départment de Biochimie, Faculté des Sciences, Université de Genève, Sciences II, 30 quai Ernest Ansermet, Geneva, Switzerland
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87
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Maravillas-Montero JL, Santos-Argumedo L. The myosin family: unconventional roles of actin-dependent molecular motors in immune cells. J Leukoc Biol 2011; 91:35-46. [DOI: 10.1189/jlb.0711335] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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88
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Function and regulation of Saccharomyces cerevisiae myosins-I in endocytic budding. Biochem Soc Trans 2011; 39:1185-90. [DOI: 10.1042/bst0391185] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Myosins-I are widely expressed actin-dependent motors which bear a phospholipid-binding domain. In addition, some members of the family can trigger Arp2/3 complex (actin-related protein 2/3 complex)-dependent actin polymerization. In the early 1990s, the development of powerful genetic tools in protozoa and mammals and discovery of these motors in yeast allowed the demonstration of their roles in membrane traffic along the endocytic and secretory pathways, in vacuole contraction, in cell motility and in mechanosensing. The powerful yeast genetics has contributed towards dissecting in detail the function and regulation of Saccharomyces cerevisiae myosins-I Myo3 and Myo5 in endocytic budding from the plasma membrane. In the present review, we summarize the evidence, dissecting their exact role in membrane budding and the molecular mechanisms controlling their recruitment and biochemical activities at the endocytic sites.
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89
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Maravillas-Montero JL, Gillespie PG, Patiño-López G, Shaw S, Santos-Argumedo L. Myosin 1c participates in B cell cytoskeleton rearrangements, is recruited to the immunologic synapse, and contributes to antigen presentation. THE JOURNAL OF IMMUNOLOGY 2011; 187:3053-63. [PMID: 21841128 DOI: 10.4049/jimmunol.1004018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Myosin 1c (Myo1c) is a member of the unconventional class I myosins of vertebrates, which directly link the plasma membrane with the microfilament cortical web. Although this molecular motor has been implicated in cell functions such as cytoskeleton organization, cell motility, nuclear transcription, and endocytosis, its role in hematopoietic cells is largely unknown. In this study, we show that Myo1c is abundantly expressed in murine B lymphocytes and is preferentially located at the plasma membrane, especially in peripheral processes such as microvilli. We observed that this motor concentrates at the growing membrane protrusions generated during B cell spreading and that it is actively recruited to the immune synapse. Interestingly, Myo1c was detected in lipid rafts of B cells and showed strong colocalization with MHC-II, particularly after cross-linking of these molecules. By transfection of a dominant negative form of Myo1c or specific siRNA, we also detected alterations in the spreading and Ag-presenting ability of these cells. The data suggest that Myo1c is involved in the cytoskeleton dynamics and membrane protein anchoring or sorting in B lymphocytes.
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Affiliation(s)
- José L Maravillas-Montero
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City CP 07360, México
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90
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Mele C, Iatropoulos P, Donadelli R, Calabria A, Maranta R, Cassis P, Buelli S, Tomasoni S, Piras R, Krendel M, Bettoni S, Morigi M, Delledonne M, Pecoraro C, Abbate I, Capobianchi MR, Hildebrandt F, Otto E, Schaefer F, Macciardi F, Ozaltin F, Emre S, Ibsirlioglu T, Benigni A, Remuzzi G, Noris M. MYO1E mutations and childhood familial focal segmental glomerulosclerosis. N Engl J Med 2011; 365:295-306. [PMID: 21756023 PMCID: PMC3701523 DOI: 10.1056/nejmoa1101273] [Citation(s) in RCA: 201] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Focal segmental glomerulosclerosis is a kidney disease that is manifested as the nephrotic syndrome. It is often resistant to glucocorticoid therapy and progresses to end-stage renal disease in 50 to 70% of patients. Genetic studies have shown that familial focal segmental glomerulosclerosis is a disease of the podocytes, which are major components of the glomerular filtration barrier. However, the molecular cause in over half the cases of primary focal segmental glomerulosclerosis is unknown, and effective treatments have been elusive. METHODS We performed whole-genome linkage analysis followed by high-throughput sequencing of the positive-linkage area in a family with autosomal recessive focal segmental glomerulosclerosis (index family) and sequenced a newly discovered gene in 52 unrelated patients with focal segmental glomerulosclerosis. Immunohistochemical studies were performed on human kidney-biopsy specimens and cultured podocytes. Expression studies in vitro were performed to characterize the functional consequences of the mutations identified. RESULTS We identified two mutations (A159P and Y695X) in MYO1E, which encodes a nonmuscle class I myosin, myosin 1E (Myo1E). The mutations in MYO1E segregated with focal segmental glomerulosclerosis in two independent pedigrees (the index family and Family 2). Patients were homozygous for the mutations and did not have a response to glucocorticoid therapy. Electron microscopy showed thickening and disorganization of the glomerular basement membrane. Normal expression of Myo1E was documented in control human kidney-biopsy specimens in vivo and in glomerular podocytes in vitro. Transfection studies revealed abnormal subcellular localization and function of the A159P-Myo1E mutant. The Y695X mutation causes loss of calmodulin binding and of the tail domains of Myo1E. CONCLUSIONS MYO1E mutations are associated with childhood-onset, glucocorticoid-resistant focal segmental glomerulosclerosis. Our data provide evidence of a role of Myo1E in podocyte function and the consequent integrity of the glomerular filtration barrier.
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Affiliation(s)
- Caterina Mele
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Paraskevas Iatropoulos
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Roberta Donadelli
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Andrea Calabria
- Department of Medicine, Surgery and Dentistry, Università degli Studi di Milano, Milan, Italy
| | - Ramona Maranta
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Paola Cassis
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Simona Buelli
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Susanna Tomasoni
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Rossella Piras
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Mira Krendel
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Serena Bettoni
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
| | - Marina Morigi
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Massimo Delledonne
- Center of Functional Genomics, Department of Biotechnologies, University of Verona, Verona Italy
| | - Carmine Pecoraro
- Department of Nephrology and Dialysis ‘Santobono’ Hospital, Napoli, Italy
| | | | | | - Friedhelm Hildebrandt
- Department of Pediatrics, University of Michigan, Ann Arbor MI, USA
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor MI, USA
| | - Edgar Otto
- Department of Pediatrics, University of Michigan, Ann Arbor MI, USA
| | - Franz Schaefer
- Pediatric Nephrology Division, Center for Pediatrics and Adolescent Medicine, Heidelberg, Germany
| | - Fabio Macciardi
- Department of Medicine, Surgery and Dentistry, Università degli Studi di Milano, Milan, Italy
| | - Fatih Ozaltin
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Sevinc Emre
- Department of Pediatric Nephrology, Instanbul Medical Faculty, Instanbul University, Instanbul, Turkey
| | - Tulin Ibsirlioglu
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Ariela Benigni
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Giuseppe Remuzzi
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori Science and Technology Park Kilometro Rosso, Bergamo, Italy
- Unit of Nephrology and Dialysis, Ospedali Riuniti di Bergamo, Bergamo Italy
| | - Marina Noris
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases ‘Aldo e Cele Daccò’, Ranica, Bergamo, Italy
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91
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Paul P, van den Hoorn T, Jongsma MLM, Bakker MJ, Hengeveld R, Janssen L, Cresswell P, Egan DA, van Ham M, Ten Brinke A, Ovaa H, Beijersbergen RL, Kuijl C, Neefjes J. A Genome-wide multidimensional RNAi screen reveals pathways controlling MHC class II antigen presentation. Cell 2011; 145:268-83. [PMID: 21458045 DOI: 10.1016/j.cell.2011.03.023] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 10/27/2010] [Accepted: 03/06/2011] [Indexed: 12/31/2022]
Abstract
MHC class II molecules (MHC-II) present peptides to T helper cells to facilitate immune responses and are strongly linked to autoimmune diseases. To unravel processes controlling MHC-II antigen presentation, we performed a genome-wide flow cytometry-based RNAi screen detecting MHC-II expression and peptide loading followed by additional high-throughput assays. All data sets were integrated to answer two fundamental questions: what regulates tissue-specific MHC-II transcription, and what controls MHC-II transport in dendritic cells? MHC-II transcription was controlled by nine regulators acting in feedback networks with higher-order control by signaling pathways, including TGFβ. MHC-II transport was controlled by the GTPase ARL14/ARF7, which recruits the motor myosin 1E via an effector protein ARF7EP. This complex controls movement of MHC-II vesicles along the actin cytoskeleton in human dendritic cells (DCs). These genome-wide systems analyses have thus identified factors and pathways controlling MHC-II transcription and transport, defining targets for manipulation of MHC-II antigen presentation in infection and autoimmunity.
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Affiliation(s)
- Petra Paul
- Division of Cell Biology and Centre for Biomedical Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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92
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Taylor MJ, Perrais D, Merrifield CJ. A high precision survey of the molecular dynamics of mammalian clathrin-mediated endocytosis. PLoS Biol 2011; 9:e1000604. [PMID: 21445324 PMCID: PMC3062526 DOI: 10.1371/journal.pbio.1000604] [Citation(s) in RCA: 559] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 02/10/2011] [Indexed: 12/15/2022] Open
Abstract
The molecular dynamics of clathrin-mediated endocytosis in living cells has been mapped with an approximately ten-fold improvement in temporal accuracy, yielding new insights into the molecular mechanism. Dual colour total internal reflection fluorescence microscopy is a powerful tool for decoding the molecular dynamics of clathrin-mediated endocytosis (CME). Typically, the recruitment of a fluorescent protein–tagged endocytic protein was referenced to the disappearance of spot-like clathrin-coated structure (CCS), but the precision of spot-like CCS disappearance as a marker for canonical CME remained unknown. Here we have used an imaging assay based on total internal reflection fluorescence microscopy to detect scission events with a resolution of ∼2 s. We found that scission events engulfed comparable amounts of transferrin receptor cargo at CCSs of different sizes and CCS did not always disappear following scission. We measured the recruitment dynamics of 34 types of endocytic protein to scission events: Abp1, ACK1, amphiphysin1, APPL1, Arp3, BIN1, CALM, CIP4, clathrin light chain (Clc), cofilin, coronin1B, cortactin, dynamin1/2, endophilin2, Eps15, Eps8, epsin2, FBP17, FCHo1/2, GAK, Hip1R, lifeAct, mu2 subunit of the AP2 complex, myosin1E, myosin6, NECAP, N-WASP, OCRL1, Rab5, SNX9, synaptojanin2β1, and syndapin2. For each protein we aligned ∼1,000 recruitment profiles to their respective scission events and constructed characteristic “recruitment signatures” that were grouped, as for yeast, to reveal the modular organization of mammalian CME. A detailed analysis revealed the unanticipated recruitment dynamics of SNX9, FBP17, and CIP4 and showed that the same set of proteins was recruited, in the same order, to scission events at CCSs of different sizes and lifetimes. Collectively these data reveal the fine-grained temporal structure of CME and suggest a simplified canonical model of mammalian CME in which the same core mechanism of CME, involving actin, operates at CCSs of diverse sizes and lifetimes. The molecular machinery of clathrin-mediated endocytosis concentrates receptors at the cell surface in a patch of membrane that curves into a vesicle, pinches off, and internalizes membrane cargo and a tiny volume of extracellular fluid. We know that dozens of proteins are involved in this process, but precisely when and where they act remains poorly understood. Here we used a fluorescence imaging assay to detect the moment of scission in living cells and used this as a reference point from which to measure the characteristic recruitment signatures of 34 fluorescently tagged endocytic proteins. Pair-wise comparison of these recruitment signatures allowed us to identify seven modules of proteins that were recruited with similar kinetics. For the most part the recruitment signatures were consistent with what was previously known about the proteins' structure and their binding affinities; however, the recruitment signatures for some components (such as some BAR and F-BAR domain proteins) could not have been predicted from existing structural or biochemical data. This study provides a paradigm for mapping molecular dynamics in living cells and provides new insights into the mechanism of clathrin-mediated endocytosis.
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Affiliation(s)
- Marcus J. Taylor
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - David Perrais
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - Christien J. Merrifield
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
- * E-mail:
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93
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Feeser EA, Ignacio CMG, Krendel M, Ostap EM. Myo1e binds anionic phospholipids with high affinity. Biochemistry 2010; 49:9353-60. [PMID: 20860408 PMCID: PMC2976041 DOI: 10.1021/bi1012657] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myo1e is a single-headed motor protein that has been shown to play roles in clathrin-mediated endocytosis in HeLa cells and podocyte function in the kidney. The myo1e C-terminal tail domain includes a basic region that is required for localization to clathrin-coated vesicles and contains a putative pleckstrin-homology (PH) domain that has been shown to play a role in phospholipid binding in other myosin-I proteins. We used sedimentation assays, stopped-flow fluorescence, and fluorescence microscopy to determine the membrane binding affinities, kinetics, and in vivo localization of fluorescently labeled recombinant myo1e-tail constructs. We found that the myo1e tail binds tightly to large unilamellar vesicles (LUVs) containing physiological concentrations of the anionic phospholipids phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) or phosphatidylserine. The rate of myo1e attachment to LUVs nears the diffusion limit while the calculated rate of detachment from LUVs is slow (k(diss) ≤ 0.4 s(-1)). Mutation of conserved residues in the myo1e PH domain has little effect on lipid binding in vitro or membrane localization in vivo. Soluble inositol phosphate headgroups, such as inositol 1,4,5-trisphosphate, can compete with PtdIns(4,5)P(2) for binding, but the apparent affinity for the soluble inositol phosphate is substantially lower than that for PtdIns(4,5)P(2). These results suggest that myo1e binds lipids through nonspecific electrostatic interactions rather than a stereospecific protein-phosphoinositide interaction.
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Affiliation(s)
- Elizabeth A. Feeser
- Pennsylvania Muscle Institute and Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA
| | - Cherry Mae G. Ignacio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Mira Krendel
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
| | - E. Michael Ostap
- Pennsylvania Muscle Institute and Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA
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94
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Calmodulin dissociation regulates Myo5 recruitment and function at endocytic sites. EMBO J 2010; 29:2899-914. [PMID: 20647997 DOI: 10.1038/emboj.2010.159] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 06/21/2010] [Indexed: 11/09/2022] Open
Abstract
Myosins-I are conserved proteins that bear an N-terminal motor head followed by a Tail Homology 1 (TH1) lipid-binding domain. Some myosins-I have an additional C-terminal extension (C(ext)) that promotes Arp2/3 complex-dependent actin polymerization. The head and the tail are separated by a neck that binds calmodulin or calmodulin-related light chains. Myosins-I are known to participate in actin-dependent membrane remodelling. However, the molecular mechanisms controlling their recruitment and their biochemical activities in vivo are far from being understood. In this study, we provided evidence suggesting the existence of an inhibitory interaction between the TH1 domain of the yeast myosin-I Myo5 and its C(ext). The TH1 domain prevented binding of the Myo5 C(ext) to the yeast WIP homologue Vrp1, Myo5 C(ext)-induced actin polymerization and recruitment of the Myo5 C(ext) to endocytic sites. Our data also indicated that calmodulin dissociation from Myo5 weakened the interaction between the neck and TH1 domains and the C(ext). Concomitantly, calmodulin dissociation triggered Myo5 binding to Vrp1, extended the myosin-I lifespan at endocytic sites and activated Myo5-induced actin polymerization.
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95
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Conibear E. Converging views of endocytosis in yeast and mammals. Curr Opin Cell Biol 2010; 22:513-8. [PMID: 20538447 DOI: 10.1016/j.ceb.2010.05.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/18/2010] [Accepted: 05/19/2010] [Indexed: 10/19/2022]
Abstract
Receptor-mediated endocytosis is important for the selective internalization of membrane proteins. In mammals, clathrin, adaptors, and dynamin play prominent roles in regulating cargo selection and vesicle formation. Endocytosis in yeast is generally conserved, but exhibits significant and perplexing differences in the relative importance of clathrin adaptors, dynamin-like proteins, and actin. Recent studies are now reconciling divergent views of endocytic processes in yeast and mammals. The discovery of cargo-specific functions for yeast homologs of mammalian clathrin adaptors has rapidly expanded the number of endocytic adaptors in yeast. Moreover, unifying models have been advanced to explain how dynamin, actin, and membrane-deforming proteins drive membrane scission. While differences remain, discoveries from each system will continue to inform the other.
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Affiliation(s)
- Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
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96
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McConnell RE, Tyska MJ. Leveraging the membrane - cytoskeleton interface with myosin-1. Trends Cell Biol 2010; 20:418-26. [PMID: 20471271 DOI: 10.1016/j.tcb.2010.04.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 12/19/2022]
Abstract
Class 1 myosins are small motor proteins with the ability to simultaneously bind to actin filaments and cellular membranes. Given their ability to generate mechanical force, and their high prevalence in many cell types, these molecules are well positioned to carry out several important biological functions at the interface of membrane and the actin cytoskeleton. Indeed, recent studies implicate these motors in endocytosis, exocytosis, release of extracellular vesicles, and the regulation of tension between membrane and the cytoskeleton. Many class 1 myosins also exhibit a load-dependent mechano-chemical cycle that enables them to maintain tension for long periods of time without hydrolyzing ATP. These properties put myosins-1 in a unique position to regulate dynamic membrane-cytoskeleton interactions and respond to physical forces during these events.
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Affiliation(s)
- Russell E McConnell
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37205, USA
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97
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Bridgman PC. Myosin motor proteins in the cell biology of axons and other neuronal compartments. Results Probl Cell Differ 2010; 48:91-105. [PMID: 19554282 DOI: 10.1007/400_2009_10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Most neurons of both the central and peripheral nervous systems express multiple members of the myosin superfamily that include nonmuscle myosin II, and a number of classes of unconventional myosins. Several classes of unconventional myosins found in neurons have been shown to play important roles in transport processes. A general picture of the myosin-dependent transport processes in neurons is beginning to emerge, although much more work still needs to be done to fully define these roles and establish the importance of myosin for axonal transport. Myosins appear to contribute to three types of transport processes in neurons; recycling of receptors or other membrane components, dynamic tethering of vesicular components, and transport or tethering of protein translational machinery including mRNA. Defects in one or more of these functions have potential to contribute to disease processes.
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Affiliation(s)
- Paul C Bridgman
- Department of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 Euclid Avenue, St. Louis, MO 63110, USA.
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98
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Liang Y, Niederstrasser H, Edwards M, Jackson CE, Cooper JA. Distinct roles for CARMIL isoforms in cell migration. Mol Biol Cell 2010; 20:5290-305. [PMID: 19846667 DOI: 10.1091/mbc.e08-10-1071] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Molecular mechanisms for cell migration, especially how signaling and cytoskeletal systems are integrated, are not understood well. Here, we examined the role of CARMIL (capping protein, Arp2/3, and Myosin-I linker) family proteins in migrating cells. Vertebrates express three conserved genes for CARMIL, and we examined the functions of the two CARMIL genes expressed in migrating human cultured cells. Both isoforms, CARMIL1 and 2, were necessary for cell migration, but for different reasons. CARMIL1 localized to lamellipodia and macropinosomes, and loss of its function caused loss of lamellipodial actin, along with defects in protrusion, ruffling, and macropinocytosis. CARMIL1-knockdown cells showed loss of activation of Rac1, and CARMIL1 was biochemically associated with the GEF Trio. CARMIL2, in contrast, colocalized with vimentin intermediate filaments, and loss of its function caused a distinctive multipolar phenotype. Loss of CARMIL2 also caused decreased levels of myosin-IIB, which may contribute to the polarity phenotype. Expression of one CARMIL isoform was not able to rescue the knockdown phenotypes of the other. Thus, the two isoforms are both important for cell migration, but they have distinct functions.
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Affiliation(s)
- Yun Liang
- Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110, USA
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Dieckmann R, von Heyden Y, Kistler C, Gopaldass N, Hausherr S, Crawley SW, Schwarz EC, Diensthuber RP, Côté GP, Tsiavaliaris G, Soldati T. A myosin IK-Abp1-PakB circuit acts as a switch to regulate phagocytosis efficiency. Mol Biol Cell 2010; 21:1505-18. [PMID: 20200225 PMCID: PMC2861610 DOI: 10.1091/mbc.e09-06-0485] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Actin dynamics and myosin (Myo) contractile forces are necessary for formation and closure of the phagocytic cup. In Dictyostelium, the actin-binding protein Abp1 and myosin IK are enriched in the closing cup and especially at an actin-dense constriction furrow formed around the neck of engulfed budded yeasts. This phagocytic furrow consists of concentric overlapping rings of MyoK, Abp1, Arp3, coronin, and myosin II, following an order strikingly reminiscent of the overall organization of the lamellipodium of migrating cells. Mutation analyses of MyoK revealed that both a C-terminal farnesylation membrane anchor and a Gly-Pro-Arg domain that interacts with profilin and Abp1 were necessary for proper localization in the furrow and efficient phagocytosis. Consequently, we measured the binding affinities of these interactions and unraveled further interactions with profilins, dynamin A, and PakB. Due to the redundancy of the interaction network, we hypothesize that MyoK and Abp1 are restricted to regulatory roles and might affect the dynamic of cup progression. Indeed, phagocytic uptake was regulated antagonistically by MyoK and Abp1. MyoK is phosphorylated by PakB and positively regulates phagocytosis, whereas binding of Abp1 negatively regulates PakB and MyoK. We conclude that a MyoK-Abp1-PakB circuit acts as a switch regulating phagocytosis efficiency of large particles.
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Affiliation(s)
- Régis Dieckmann
- Départment de Biochimie, Faculté des Sciences, Université de Genève, Sciences II, CH-1211-Genève-4, Switzerland
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100
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Dynamin 2 and human diseases. J Mol Med (Berl) 2010; 88:339-50. [PMID: 20127478 DOI: 10.1007/s00109-009-0587-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 12/21/2009] [Accepted: 12/25/2009] [Indexed: 10/25/2022]
Abstract
Dynamin 2 (DNM2) mutations cause autosomal dominant centronuclear myopathy, a rare form of congenital myopathy, and intermediate and axonal forms of Charcot-Marie-Tooth disease, a peripheral neuropathy. DNM2 is a large GTPase mainly involved in membrane trafficking through its function in the formation and release of nascent vesicles from biological membranes. DNM2 participates in clathrin-dependent and clathrin-independent endocytosis and intracellular membrane trafficking (from endosomes and Golgi apparatus). Recent studies have also implicated DNM2 in exocytosis. DNM2 belongs to the machinery responsible for the formation of vesicles and regulates the cytoskeleton providing intracellular vesicle transport. In addition, DNM2 tightly interacts with and is involved in the regulation of actin and microtubule networks, independent from membrane trafficking processes. We summarize here the molecular, biochemical, and functional data on DNM2 and discuss the possible pathophysiological mechanisms via which DNM2 mutations can lead to two distinct neuromuscular disorders.
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