1
|
Schmid SL. Reciprocal regulation of signaling and endocytosis: Implications for the evolving cancer cell. J Cell Biol 2017; 216:2623-2632. [PMID: 28674108 PMCID: PMC5584184 DOI: 10.1083/jcb.201705017] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/05/2017] [Accepted: 06/08/2017] [Indexed: 12/19/2022] Open
Abstract
Schmid provides a perspective on exciting new research examining the relationship between signaling and endocytosis in cancer. Cell surface receptor uptake via clathrin-mediated endocytosis (CME) and subsequent intracellular sorting for degradation or recycling regulates the strength and specificity of downstream signaling. Signaling, in turn, modulates early endocytic trafficking. This reciprocal regulation of signaling and endocytosis provides opportunities for the establishment of feedback loops to enhance or suppress surface-derived signals. Recent studies suggest that dynamin-1, a presumed neuron-specific isoform of the large, membrane fission GTPase, can be activated in nonneuronal cells downstream of cancer-relevant signaling pathways and thereby function as a nexus between signaling and early endocytic trafficking. I speculate that sustained up-regulation and/or acute activation of dynamin-1 in cancer cells contributes to a program of “adaptive” CME that alters signaling to enhance cancer cell survival, migration, and proliferation.
Collapse
Affiliation(s)
- Sandra L Schmid
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| |
Collapse
|
2
|
Abstract
The GTPase dynamin is essential for CME (clathrin-mediated endocytosis), but its exact function and mechanism of action have been controversial. Here, we review findings that have led to the current models for dynamin function, either as a mechanochemical enzyme driving membrane fission or as a regulatory GTPase monitoring rate-limiting steps in CME. However, these models are not mutually exclusive and subsequent studies have provided evidence for both dynamin functions. Recent evidence derived from divergent in vivo and in vitro approaches suggests that dynamin plays a dual role in CME, functioning at early stages as a fidelity monitor to regulate clathrin-coated pit maturation and at later stages to directly catalyse membrane fission and clathrin-coated vesicle formation.
Collapse
|
3
|
Kirchhausen T, Macia E, Pelish HE. Use of dynasore, the small molecule inhibitor of dynamin, in the regulation of endocytosis. Methods Enzymol 2008; 438:77-93. [PMID: 18413242 DOI: 10.1016/s0076-6879(07)38006-3] [Citation(s) in RCA: 334] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The large GTPase dynamin is essential for clathrin-dependent coated-vesicle formation. Dynasore is a cell-permeable small molecule that inhibits the GTPase activity of dynamin1, dynamin2 and Drp1, the mitochondrial dynamin. Dynasore was discovered in a screen of approximately 16,000 compounds for inhibitors of the dynamin2 GTPase. Dynasore is a noncompetitive inhibitor of dynamin GTPase activity and blocks dynamin-dependent endocytosis in cells, including neurons. It is fast acting (seconds) and its inhibitory effect in cells can be reversed by washout. Here we present a detailed synthesis protocol for dynasore, and describe a series of experiments used to analyze the inhibitory effects of dynasore on dynamin in vitro and to study the effects of dynasore on endocytosis in cells.
Collapse
Affiliation(s)
- Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School, and IDI Immune Research Institute, Boston, Massachusetts, USA
| | | | | |
Collapse
|
4
|
Macia E, Ehrlich M, Massol R, Boucrot E, Brunner C, Kirchhausen T. Dynasore, a Cell-Permeable Inhibitor of Dynamin. Dev Cell 2006; 10:839-50. [PMID: 16740485 DOI: 10.1016/j.devcel.2006.04.002] [Citation(s) in RCA: 1583] [Impact Index Per Article: 87.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 03/22/2006] [Accepted: 04/03/2006] [Indexed: 11/25/2022]
Abstract
Dynamin is essential for clathrin-dependent coated vesicle formation. It is required for membrane budding at a late stage during the transition from a fully formed pit to a pinched-off vesicle. Dynamin may also fulfill other roles during earlier stages of vesicle formation. We have screened about 16,000 small molecules and have identified 1, named here dynasore, that interferes in vitro with the GTPase activity of dynamin1, dynamin2, and Drp1, the mitochondrial dynamin, but not of other small GTPases. Dynasore acts as a potent inhibitor of endocytic pathways known to depend on dynamin by rapidly blocking coated vesicle formation within seconds of dynasore addition. Two types of coated pit intermediates accumulate during dynasore treatment, U-shaped, half formed pits and O-shaped, fully formed pits, captured while pinching off. Thus, dynamin acts at two steps during clathrin coat formation; GTP hydrolysis is probably needed at both steps.
Collapse
Affiliation(s)
- Eric Macia
- Department of Cell Biology, Harvard Medical School and the CBR Institute for Biomedical Research, Inc., 200 Longwood Avenue, Boston, Massachusetts 02115, USA
| | | | | | | | | | | |
Collapse
|
5
|
Abstract
In this review we describe the potential roles of the actin cytoskeleton in receptor-mediated endocytosis in mammalian cells and summarize the efforts of recent years in establishing a relationship between these two cellular functions. With molecules such as dynamin, syndapin, HIP1R, Abp1, synaptojanin, N-WASP, intersectin, and cortactin a set of molecular links is now available and it is likely that their further characterization will reveal the basic principles of a functional interconnection between the membrane cytoskeleton and the vesicle-budding machinery. We will therefore discuss proteins involved in endocytic clathrin coat formation and accessory factors to control and regulate coated vesicle formation but we will also focus on actin cytoskeletal components such as the Arp2/3 complex, spectrin, profilin, and motor proteins involved in actin dynamics and organization. Additionally, we will discuss how phosphoinositides, such as PI(4,5)P2, small GTPases thought to control the actin cytoskeleton, such as Rho, Rac, and Cdc42, or membrane trafficking, such as Rab GTPases and ARF proteins, and different kinases may participate in the functional connection of actin and endocytosis. We will compare the concepts and different molecular mechanisms involved in mammalian cells with yeast as well as with specialized cells, such as epithelial cells and neurons, because different model organisms often offer complementary advantages for further studies in this thriving field of current cell biological research.
Collapse
Affiliation(s)
- Britta Qualmann
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | |
Collapse
|
6
|
Yaguchi H, Ohkura N, Tsukada T, Yamaguchi K. Menin, the multiple endocrine neoplasia type 1 gene product, exhibits GTP-hydrolyzing activity in the presence of the tumor metastasis suppressor nm23. J Biol Chem 2002; 277:38197-204. [PMID: 12145286 DOI: 10.1074/jbc.m204132200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MEN1, the gene responsible for multiple endocrine neoplasia type 1, is a tumor suppressor gene that encodes a protein called menin, of unknown function with no homology to any known protein. Here we demonstrate that menin interacts with a putative tumor metastasis suppressor nm23H1/nucleoside diphosphate (NDP) kinase A in mammalian cells. Given the roles of nm23 as a multi-functional protein, we searched for the possible function of menin. Menin has no effect on the known activities of nm23; that is, nucleoside diphosphate kinase, protein kinase, or GTPase-activating protein for Ras-related GTPase Rad. However, we found that menin hydrolyzes GTP to GDP efficiently in the presence of nm23, whereas nm23 or menin alone shows little or no detectable GTPase activity. Furthermore, menin contains sequence motifs similar to those found in all known GTPases or GTP-binding proteins and shows low affinity but specific binding to GTP/GDP. These results suggest that menin is an atypical GTPase stimulated by nm23.
Collapse
Affiliation(s)
- Hiroko Yaguchi
- Growth Factor Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | | | | | | |
Collapse
|
7
|
Abstract
The process of endocytosis is a complex series of events involving the coordinated activity of many proteins. In animal cells, clathrin plays a vital role in the invagination of the plasma membrane leading to formation of vesicles during endocytosis. The study of endocytosis in yeast cells has been hindered by a debate about the role of clathrin in early internalization steps. This review summarizes the evidence for and against clathrin's involvement in internalization from the yeast plasma membrane.
Collapse
Affiliation(s)
- J J Baggett
- Department of Biology, The Johns Hopkins University, 3400 N. Charles St Baltimore, MD 21218, USA
| | | |
Collapse
|
8
|
Niemann HH, Knetsch ML, Scherer A, Manstein DJ, Kull F. Crystal structure of a dynamin GTPase domain in both nucleotide-free and GDP-bound forms. EMBO J 2001; 20:5813-21. [PMID: 11689422 PMCID: PMC125706 DOI: 10.1093/emboj/20.21.5813] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dynamins form a family of multidomain GTPases involved in endocytosis, vesicle trafficking and maintenance of mitochondrial morphology. In contrast to the classical switch GTPases, a force-generating function has been suggested for dynamins. Here we report the 2.3 A crystal structure of the nucleotide-free and GDP-bound GTPase domain of Dictyostelium discoideum dynamin A. The GTPase domain is the most highly conserved region among dynamins. The globular structure contains the G-protein core fold, which is extended from a six-stranded beta-sheet to an eight-stranded one by a 55 amino acid insertion. This topologically unique insertion distinguishes dynamins from other subfamilies of GTP-binding proteins. An additional N-terminal helix interacts with the C-terminal helix of the GTPase domain, forming a hydrophobic groove, which could be occupied by C-terminal parts of dynamin not present in our construct. The lack of major conformational changes between the nucleotide-free and the GDP-bound state suggests that mechanochemical rearrangements in dynamin occur during GTP binding, GTP hydrolysis or phosphate release and are not linked to loss of GDP.
Collapse
Affiliation(s)
| | | | | | | | - F.Jon Kull
- Department of Biophysics, Max-Planck-Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
Corresponding author e-mail:
| |
Collapse
|
9
|
Pucharcos C, Casas C, Nadal M, Estivill X, de la Luna S. The human intersectin genes and their spliced variants are differentially expressed. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1521:1-11. [PMID: 11690630 DOI: 10.1016/s0167-4781(01)00276-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Human intersectins (ITSN1 and ITSN2) are members of a conserved family of proteins involved in clathrin-mediated endocytosis. A short and a long isoform with different protein domain compositions have been described for both human intersectins. Here, we have resolved the exon/intron structure of the ITSN2 gene to explain the genomic origin of its alternatively spliced transcripts. Comparison of the two ITSN human genes shows a high level of conservation in their genomic organization, including the main alternative splicing events. An extensive tissue expression analysis of the two predominant transcripts as well as other minor variants shows that ITSN expression is under tissue and developmental controls. Their differential expression is made more evident when the expression of both intersectins is studied by in situ hybridization in mouse brain.
Collapse
Affiliation(s)
- C Pucharcos
- Down Syndrome Research Group, Medical and Molecular Genetics Center-IRO, Gran Via s/n Km 2.7, L'Hospitalet de Llobregat, 08907, Barcelona, Spain
| | | | | | | | | |
Collapse
|
10
|
Fukushima NH, Brisch E, Keegan BR, Bleazard W, Shaw JM. The GTPase effector domain sequence of the Dnm1p GTPase regulates self-assembly and controls a rate-limiting step in mitochondrial fission. Mol Biol Cell 2001; 12:2756-66. [PMID: 11553714 PMCID: PMC59710 DOI: 10.1091/mbc.12.9.2756] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2001] [Revised: 05/30/2001] [Accepted: 06/19/2001] [Indexed: 12/23/2022] Open
Abstract
Dnm1p belongs to a family of dynamin-related GTPases required to remodel different cellular membranes. In budding yeast, Dnm1p-containing complexes assemble on the cytoplasmic surface of the outer mitochondrial membrane at sites where mitochondrial tubules divide. Our previous genetic studies suggested that Dnm1p's GTPase activity was required for mitochondrial fission and that Dnm1p interacted with itself. In this study, we show that bacterially expressed Dnm1p can bind and hydrolyze GTP in vitro. Coimmunoprecipitation studies and yeast two-hybrid analysis suggest that Dnm1p oligomerizes in vivo. With the use of the yeast two-hybrid system, we show that this Dnm1p oligomerization is mediated, in part, by a C-terminal sequence related to the GTPase effector domain (GED) in dynamin. The Dnm1p interactions characterized here are similar to those reported for dynamin and dynamin-related proteins that form higher order structures in vivo, suggesting that Dnm1p assembles to form rings or collars that surround mitochondrial tubules. Based on previous findings, a K705A mutation in the Dnm1p GED is predicted to interfere with GTP hydrolysis, stabilize active Dnm1p-GTP, and stimulate a rate-limiting step in fission. Here we show that expression of the Dnm1 K705A protein in yeast enhances mitochondrial fission. Our results provide evidence that the GED region of a dynamin-related protein modulates a rate-limiting step in membrane fission.
Collapse
Affiliation(s)
- N H Fukushima
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | | | | | | | | |
Collapse
|
11
|
Jeong MJ, Yoo J, Lee SS, Lee KI, Cho A, Kwon BM, Moon MJ, Park YM, Han MY. Increased GTP-binding to dynamin II does not stimulate receptor-mediated endocytosis. Biochem Biophys Res Commun 2001; 283:136-42. [PMID: 11322780 DOI: 10.1006/bbrc.2001.4681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regarding the molecular mechanism of dynamin in receptor-mediated endocytosis, GTPase activity of dynamin has been thought to have a critical role in endocytic vesicle internalization. However, a recent report suggested that GTP-binding to dynamin itself activates the dynamin to recruit molecular machinery necessary for endocytosis. In this study, to investigate the role of GTP binding to dynamin II, we generated two mutant dynamin II constructs: G38V and K44E. G38V, its GTP binding site might be mainly occupied by GTP caused by reduced GTPase activity, and K44E mutant, its GTP binding site might be vacant, caused by its decreased affinity for GTP and GDP. From the analysis of the ratio of GTP vs GDP bound to dynamin, we confirmed these properties. To test the effect of these mutant dynamins on endocytosis, we performed flow cytometry and confocal immunofluorescence analysis and found that these two mutants have inhibitory effect on transferrin-induced endocytosis. Whereas fluorescent transferrin was completely internalized in wild-type (WT) dynamin II expressing cells, no intracellular accumulation of fluorescent transferrin was found in the cells overexpressing K44E and G38V mutant. Interestingly, the amount of GTP bound to K44E was increased when endocytosis was induced than that bound to WT. The present results suggested that the GTPase activity of dynamin II is required for formation of endocytic vesicle and GTP-binding to dynamin II per se is not sufficient for stimulating endocytosis.
Collapse
Affiliation(s)
- M J Jeong
- Cell Biology Laboratory, Korea Research Institute of Bioscience and Biotechnology, Taejon, Yusung, 305-600, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Lee A, Lemmon MA. Analysis of phosphoinositide binding by pleckstrin homology domain from dynamin. Methods Enzymol 2001; 329:457-68. [PMID: 11210566 DOI: 10.1016/s0076-6879(01)29107-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- A Lee
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Johnson Research Foundation, Philadelphia, Pennsylvania 19104-6059, USA
| | | |
Collapse
|
13
|
Abstract
Genetic and biochemical studies in yeast and animal cells have led to the identification of many components required for endocytosis. In this review, we summarize our understanding of the endocytic machinery with an emphasis on the proteins regulating the internalization step of endocytosis and endosome fusion. Even though the overall endocytic machinery appears to be conserved between yeast and animals, clear differences exist. We also discuss the roles of phosphoinositides, sterols, and sphingolipid precursors in endocytosis, because in addition to proteins, these lipids have emerged as important determinants in the spatial and most likely temporal specificity of endocytic membrane trafficking events.
Collapse
Affiliation(s)
- K D'Hondt
- Biozentrum-University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
| | | | | |
Collapse
|
14
|
Hill E, van der Kaay J, Downes CP, Smythe E. The role of dynamin and its binding partners in coated pit invagination and scission. J Cell Biol 2001; 152:309-23. [PMID: 11266448 PMCID: PMC2199618 DOI: 10.1083/jcb.152.2.309] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Plasma membrane clathrin-coated vesicles form after the directed assembly of clathrin and the adaptor complex, AP2, from the cytosol onto the membrane. In addition to these structural components, several other proteins have been implicated in clathrin-coated vesicle formation. These include the large molecular weight GTPase, dynamin, and several Src homology 3 (SH3) domain-containing proteins which bind to dynamin via interactions with its COOH-terminal proline/arginine-rich domain (PRD). To understand the mechanism of coated vesicle formation, it is essential to determine the hierarchy by which individual components are targeted to and act in coated pit assembly, invagination, and scission. To address the role of dynamin and its binding partners in the early stages of endocytosis, we have used well-established in vitro assays for the late stages of coated pit invagination and coated vesicle scission. Dynamin has previously been shown to have a role in scission of coated vesicles. We show that dynamin is also required for the late stages of invagination of clathrin-coated pits. Furthermore, dynamin must bind and hydrolyze GTP for its role in sequestering ligand into deeply invaginated coated pits. We also demonstrate that the SH3 domain of endophilin, which binds both synaptojanin and dynamin, inhibits both late stages of invagination and also scission in vitro. This inhibition results from a reduction in phosphoinositide 4,5-bisphosphate levels which causes dissociation of AP2, clathrin, and dynamin from the plasma membrane. The dramatic effects of the SH3 domain of endophilin led us to propose a model for the temporal order of addition of endophilin and its binding partner synaptojanin in the coated vesicle cycle.
Collapse
Affiliation(s)
- Elaine Hill
- Division of Molecular Cell Biology, Wellcome Trust Biocentre, Dundee DD1 5EH, United Kingdom
| | - Jeroen van der Kaay
- Medical Sciences Institute, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - C. Peter Downes
- Medical Sciences Institute, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Elizabeth Smythe
- Division of Molecular Cell Biology, Wellcome Trust Biocentre, Dundee DD1 5EH, United Kingdom
| |
Collapse
|
15
|
Abstract
Cargo molecules have to be included in carrier vesicles of different forms and sizes to be transported between organelles. During this process, a limited set of proteins, including the coat proteins COPI, COPII and clathrin, carries out a programmed set of sequential interactions that lead to the budding of vesicles. A general model to explain the formation of coated vesicles is starting to emerge but the picture is more complex than we had imagined.
Collapse
Affiliation(s)
- T Kirchhausen
- Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
| |
Collapse
|
16
|
Vestal DJ, Gorbacheva VY, Sen GC. Different subcellular localizations for the related interferon-induced GTPases, MuGBP-1 and MuGBP-2: implications for different functions? J Interferon Cytokine Res 2000; 20:991-1000. [PMID: 11096456 DOI: 10.1089/10799900050198435] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The guanylate-binding proteins (GBPs) are a family of 65-67-kDa proteins induced by both type I and type II interferons (IFN). Members of the GBP family of GTPases are among the most abundant IFN-gamma-induced proteins. GBPs contain an unusual GTP binding site, which is consistent with GBP hydrolysis of GTP to both GDP and GMP. In addition, six of the eight known GBPs have a carboxy-terminal CaaX motif for the addition of isoprenyl lipids. Despite their abundance, however, little is known about the biologic function or cellular location of GBPs. We report here on studies to localize both a newly identified murine GBP (MuGBP-2) and its closely related family member, MuGBP-1. In both IFN-treated macrophages and fibroblasts, MuGBP-2 is found in both a granular distribution throughout the cytoplasm and localized to vesicle populations of heterogeneous sizes. The localization of MuGBP-2 to vesicles is dependent on its isoprenylation. Despite a high degree of sequence identity and the presence of an identical CaaX sequence, MuGBP-1 has a very homogeneous cytoplasmic distribution and fails to localize to intracellular vesicles. The different intracellular distribution of these two closely related family members suggests differential function(s).
Collapse
Affiliation(s)
- D J Vestal
- Department of Molecular Biology of the Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
| | | | | |
Collapse
|
17
|
Abstract
The GTPase dynamin is essential for clathrin-mediated endocytosis. Numerous new and exciting discoveries regarding dynamin function in vivo and in vitro have led to various models in which dynamin functions directly in membrane fission and the release of clathrin-coated vesicles from the plasma membrane. This would make dynamin unique among GTPases in its ability to act as a mechanochemical enzyme. Here we review the various models and their supporting data. We then discuss new findings that raise doubts as to whether dynamin breaks the paradigm that governs regulatory GTPases.
Collapse
Affiliation(s)
- S Sever
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Dana Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
| | | | | |
Collapse
|
18
|
McNiven MA, Cao H, Pitts KR, Yoon Y. The dynamin family of mechanoenzymes: pinching in new places. Trends Biochem Sci 2000; 25:115-20. [PMID: 10694881 DOI: 10.1016/s0968-0004(99)01538-8] [Citation(s) in RCA: 284] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The large GTPase dynamin is a mechanoenzyme that mediates the liberation of nascent clathrin-coated pits from the plasma membrane during endocytosis. Recently, this enzyme has been demonstrated to comprise an extensive family of related proteins that have been implicated in a large variety of vesicle trafficking events during endocytosis, secretion and even maintenance of mitochondrial form. The potential contributions by the dynamin family to these diverse but related functions are discussed.
Collapse
Affiliation(s)
- M A McNiven
- Dept of Biochemistry and Molecular Biology, The Center for Basic Research in Digestive Diseases, Mayo Foundation, Rochester, MN 55905, USA.
| | | | | | | |
Collapse
|
19
|
Roy AM, Parker JS, Parrish CR, Whittaker GR. Early stages of influenza virus entry into Mv-1 lung cells: involvement of dynamin. Virology 2000; 267:17-28. [PMID: 10648179 DOI: 10.1006/viro.1999.0109] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Viruses generally have one of two mechanisms for entry and uncoating. They can enter the cell either by endocytosis or by direct fusion at the plasma membrane. We have established a novel mink lung (Mv-1) cell line that expresses a dominant-interfering form of dynamin-1 (K44A) under the control of a tetracycline-responsive element and studied the early events in influenza infection using these cells. We found that influenza virus binds equally to both induced and uninduced cells, but in K44A-expressing cells, electron microscopy showed viruses trapped in deep coated pits and irregular-shaped tubular structures that contain discrete coated regions. We also show by immunofluorescence and confocal microscopy that entry of incoming virus into the nucleus is blocked in K44A-expressing cells. Virus replication was assayed by immunofluorescence microscopy and was strongly inhibited at both early and late times postinfection in K44A-expressing cells. Virus infectivity was inhibited by approximately 2 log units in cells expressing K44A dynamin when analyzed by influenza plaque assay. Overall these data show that dynamin is required for efficient influenza virus entry, presumably due to its function in release of vesicles from coated pits.
Collapse
Affiliation(s)
- A M Roy
- Department of Microbiology, Cornell University, Ithaca, New York, 14853, USA
| | | | | | | |
Collapse
|
20
|
Kranenburg O, Verlaan I, Moolenaar WH. Dynamin is required for the activation of mitogen-activated protein (MAP) kinase by MAP kinase kinase. J Biol Chem 1999; 274:35301-4. [PMID: 10585393 DOI: 10.1074/jbc.274.50.35301] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Internalization of activated receptors from the plasma membrane has been implicated in the activation of mitogen-activated protein (MAP) kinase. However, the mechanism whereby membrane trafficking may regulate mitogenic signaling remains unclear. Here we report that dominant-negative dynamin (K44A), an inhibitor of endocytic vesicle formation, abrogates MAP kinase activation in response to epidermal growth factor, lysophosphatidic acid, and protein kinase C-activating phorbol ester. In contrast, dynamin-K44A does not affect the activation of Ras, Raf, and MAP kinase kinase (MEK) by either agonist. Through immunofluorescence and subcellular fractionation studies, we find that activated MEK is present both at the plasma membrane and in intracellular vesicles but not in the cytosol. Our findings suggest that dynamin-regulated endocytosis of activated MEK, rather than activated receptors, is a critical event in the MAP kinase activation cascade.
Collapse
Affiliation(s)
- O Kranenburg
- Division of Cellular Biochemistry, The Netherlands Cancer Institute and Centre for Biomedical Genetics, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
| | | | | |
Collapse
|