101
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The ubiquitin ligase HACE1 regulates Golgi membrane dynamics during the cell cycle. Nat Commun 2011; 2:501. [PMID: 21988917 DOI: 10.1038/ncomms1509] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 09/13/2011] [Indexed: 11/09/2022] Open
Abstract
Partitioning of the Golgi membrane into daughter cells during mammalian cell division occurs through a unique disassembly and reassembly process that is regulated by ubiquitination. However, the identity of the ubiquitin ligase is unknown. Here we show that the Homologous to the E6-AP Carboxyl Terminus (HECT) domain containing ubiquitin ligase HACE1 is targeted to the Golgi membrane through interactions with Rab proteins. The ubiquitin ligase activity of HACE1 in mitotic Golgi disassembly is required for subsequent postmitotic Golgi membrane fusion. Depletion of HACE1 using small interfering RNAs or expression of an inactive HACE1 mutant protein in cells impaired postmitotic Golgi membrane fusion. The identification of HACE1 as a Golgi-localized ubiquitin ligase provides evidence that ubiquitin has a critical role in Golgi biogenesis during the cell cycle.
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102
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Abstract
The Golgi is an essential membrane-bound organelle in the secretary pathway of eukaryotic cells. In mammalian cells, the Golgi stacks are integrated into a continuous perinuclear ribbon, which poses a challenge for the daughter cells to inherit this membrane organelle during cell division. To facilitate proper partitioning, the mammalian Golgi ribbon is disassembled into vesicles in early mitosis. Following segregation into the daughter cells, a functional Golgi is reformed. Here we summarize our current understanding of the molecular mechanisms that control the mitotic Golgi disassembly and postmitotic reassembly cycle in mammalian cells.
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Affiliation(s)
- Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
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103
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Abstract
During the G2-M transition, the highly organized Golgi apparatus undergoes reversible fragmentation through unstacking of the cisternal ribbon and disassembly into radially dispersed vesicles and tubules. These Golgi-derived fragments redistribute randomly within the cytoplasm, partition stochastically, and in telophase coalesce to generate a functionally and structurally intact Golgi complex. Here we identified a novel step in postmitotic Golgi reassembly that requires the clathrin heavy chain (CHC). We used siRNA-mediated CHC knockdown, biochemistry, and morphological analysis and showed that the spindle- and spindle pole-associated clathrin pools are membrane-bound and required for postmitotic Golgi reassembly. The results presented here show that clathrin remains associated with the spindle poles throughout mitosis and that this clathrin pool is distinct from the previously characterized spindle-associated population. We suggest that clathrin may provide a template for postmitotic Golgi reassembly and cisternal remodeling. In absence of the CHC, the Golgi apparatus remained disconnected and disordered and failed to regain its characteristic perinuclear, lace-like morphology. Our findings build on previous independent reports that clathrin is required for Golgi reassembly following disruption with pharmacological agents and for mitotic chromosome congression.
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Affiliation(s)
- Andreea E Radulescu
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
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104
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Abstract
The Golgi is essential for processing proteins and sorting them, as well as plasma membrane components, to their final destinations. Not surprisingly, this organelle, a major compartment of the secretory pathway, is an important venue for regulating many aspects of development in both invertebrates and vertebrates. Through its role as a site for protein cleavage and glycosylation as well as through changes in its spatial organization and secretory trafficking, the Golgi exerts highly specific effects on cellular differentiation and morphogenesis by spatially and temporally constraining developmental pathways.
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105
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Tängemo C, Ronchi P, Colombelli J, Haselmann U, Simpson JC, Antony C, Stelzer EHK, Pepperkok R, Reynaud EG. A novel laser nanosurgery approach supports de novo Golgi biogenesis in mammalian cells. J Cell Sci 2011; 124:978-87. [PMID: 21378314 DOI: 10.1242/jcs.079640] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Golgi complex has a central role in the secretory pathway of all higher organisms. To explain the synthesis of its unique stacked structure in mammalian cells, two major models have been proposed. One suggests that it is synthesized de novo from the endoplasmic reticulum. The second model postulates a pre-existing Golgi template that serves as a scaffold for its biogenesis. To test these hypotheses directly, we have developed an approach in which we deplete the Golgi complex from living cells by laser nanosurgery, and subsequently analyze the 'Golgi-depleted' karyoplast using time-lapse and electron microscopy. We show that biosynthetic transport is blocked after Golgi depletion, but is restored 12 hours later. This recovery of secretory transport coincides with an ordered assembly of stacked Golgi structures, and we also observe the appearance of matrix proteins before that of Golgi enzymes. Functional experiments using RNA interference-mediated knockdown of GM130 further demonstrate the importance of the matrix during Golgi biogenesis. By contrast, the centrosome, which can also be removed by laser nanosurgery and is not reformed within the considered time frame, is not required for this process. Altogether, our data provide evidence that de novo Golgi biogenesis can occur in mammalian cells.
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Affiliation(s)
- Carolina Tängemo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
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106
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Litterman N, Ikeuchi Y, Gallardo G, O'Connell BC, Sowa ME, Gygi SP, Harper JW, Bonni A. An OBSL1-Cul7Fbxw8 ubiquitin ligase signaling mechanism regulates Golgi morphology and dendrite patterning. PLoS Biol 2011; 9:e1001060. [PMID: 21572988 PMCID: PMC3091842 DOI: 10.1371/journal.pbio.1001060] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 03/25/2011] [Indexed: 12/22/2022] Open
Abstract
The elaboration of dendrites in neurons requires secretory trafficking through the Golgi apparatus, but the mechanisms that govern Golgi function in neuronal morphogenesis in the brain have remained largely unexplored. Here, we report that the E3 ubiquitin ligase Cul7Fbxw8 localizes to the Golgi complex in mammalian brain neurons. Inhibition of Cul7Fbxw8 by independent approaches including Fbxw8 knockdown reveals that Cul7Fbxw8 is selectively required for the growth and elaboration of dendrites but not axons in primary neurons and in the developing rat cerebellum in vivo. Inhibition of Cul7Fbxw8 also dramatically impairs the morphology of the Golgi complex, leading to deficient secretory trafficking in neurons. Using an immunoprecipitation/mass spectrometry screening approach, we also uncover the cytoskeletal adaptor protein OBSL1 as a critical regulator of Cul7Fbxw8 in Golgi morphogenesis and dendrite elaboration. OBSL1 forms a physical complex with the scaffold protein Cul7 and thereby localizes Cul7 at the Golgi apparatus. Accordingly, OBSL1 is required for the morphogenesis of the Golgi apparatus and the elaboration of dendrites. Finally, we identify the Golgi protein Grasp65 as a novel and physiologically relevant substrate of Cul7Fbxw8 in the control of Golgi and dendrite morphogenesis in neurons. Collectively, these findings define a novel OBSL1-regulated Cul7Fbxw8 ubiquitin signaling mechanism that orchestrates the morphogenesis of the Golgi apparatus and patterning of dendrites, with fundamental implications for our understanding of brain development. The growth and elaboration of dendrites is an essential step in the establishment of neuronal circuits in the brain. Because dendrites house the receptive components of neurotransmission and actively integrate synaptic inputs, variations in dendrite architecture have important consequences for information processing. The development of dendrites relies on secretory trafficking through the Golgi apparatus. In this study, we have identified an E3 ubiquitin ligase, Cul7Fbxw8, that localizes to the Golgi apparatus in neurons. E3 ubiquitin ligases regulate the abundance of target proteins by directing ubiquitin-dependent proteolysis of specific targets. We have found that Cul7Fbxw8 operates at the Golgi apparatus to control Golgi integrity and dendrite patterning. We have also identified the cytoskeletal adaptor protein OBSL1 as an important regulator of Cul7Fbxw8 function in neurons. OBSL1 promotes the function of Cul7Fbxw8 by localizing Cul7 at the Golgi apparatus. Finally, we have found that Cul7Fbxw8 induces the ubiquitination and degradation of the Golgi protein Grasp65 to control Golgi morphology and dendrite elaboration. We conclude that the signaling cascade from OBSL1 to Cul7Fbxw8 to Grasp65 is an important means of regulating Golgi morphology and consequently the shape and size of dendrite arbors in neurons.
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Affiliation(s)
- Nadia Litterman
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yoshiho Ikeuchi
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gilbert Gallardo
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Brenda C. O'Connell
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mathew E. Sowa
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - J. Wade Harper
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Azad Bonni
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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107
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Abstract
The eukaryotic Golgi apparatus is characterized by a stack of flattened cisternae that are surrounded by transport vesicles. The organization and function of the Golgi require Golgi matrix proteins, including GRASPs and golgins, which exist primarily as fiber-like bridges between Golgi cisternae or between cisternae and vesicles. In this review, we highlight recent findings on Golgi matrix proteins, including their roles in maintaining the Golgi structure, vesicle tethering, and novel, unexpected functions. These new discoveries further our understanding of the molecular mechanisms that maintain the structure and the function of the Golgi, as well as its relationship with other cellular organelles such as the centrosome.
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108
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Pokrovskaya ID, Willett R, Smith RD, Morelle W, Kudlyk T, Lupashin VV. Conserved oligomeric Golgi complex specifically regulates the maintenance of Golgi glycosylation machinery. Glycobiology 2011; 21:1554-69. [PMID: 21421995 DOI: 10.1093/glycob/cwr028] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cell surface lectin staining, examination of Golgi glycosyltransferases stability and localization, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis were employed to investigate conserved oligomeric Golgi (COG)-dependent glycosylation defects in HeLa cells. Both Griffonia simplicifolia lectin-II and Galanthus nivalus lectins were specifically bound to the plasma membrane glycoconjugates of COG-depleted cells, indicating defects in activity of medial- and trans-Golgi-localized enzymes. In response to siRNA-induced depletion of COG complex subunits, several key components of Golgi glycosylation machinery, including MAN2A1, MGAT1, B4GALT1 and ST6GAL1, were severely mislocalized. MALDI-TOF analysis of total N-linked glycoconjugates indicated a decrease in the relative amount of sialylated glycans in both COG3 KD and COG4 KD cells. In agreement to a proposed role of the COG complex in retrograde membrane trafficking, all types of COG-depleted HeLa cells were deficient in the Brefeldin A- and Sar1 DN-induced redistribution of Golgi resident glycosyltransferases to the endoplasmic reticulum. The retrograde trafficking of medial- and trans-Golgi-localized glycosylation enzymes was affected to a larger extent, strongly indicating that the COG complex regulates the intra-Golgi protein movement. COG complex-deficient cells were not defective in Golgi re-assembly after the Brefeldin A washout, confirming specificity in the retrograde trafficking block. The lobe B COG subcomplex subunits COG6 and COG8 were localized on trafficking intermediates that carry Golgi glycosyltransferases, indicating that the COG complex is directly involved in trafficking and maintenance of Golgi glycosylation machinery.
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Affiliation(s)
- Irina D Pokrovskaya
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, 4301 W. Markham, Slot 505, Little Rock, AR 72205, USA
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109
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Fiset A, Xu E, Bergeron S, Marette A, Pelletier G, Siminovitch KA, Olivier M, Beauchemin N, Faure RL. Compartmentalized CDK2 is connected with SHP-1 and β-catenin and regulates insulin internalization. Cell Signal 2011; 23:911-9. [PMID: 21262353 DOI: 10.1016/j.cellsig.2011.01.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 01/14/2011] [Indexed: 12/31/2022]
Abstract
The cyclin-dependant kinase Cdk2 is compartmentalized in endosomes but its role is poorly understood. Here we show that Cdk2 present in hepatic endosome fractions is strictly located in a Triton X-100-resistant environment. The endosomal Cdk2 was found to be associated with the protein tyrosine phosphatase SHP-1, a regulator of insulin clearance, and the actin anchor β-catenin, a known substrate for both Cdk2 and SHP-1. In the plasma membranes and endosome fractions, β-catenin is associated with CEACAM1, also known as regulator of insulin clearance. We show that β-catenin, not CEACAM1, is a substrate for Cdk2. Partial down-modulation of Cdk2 in HEK293 cells increased the rate of insulin internalization. These findings reveal that Cdk2 functions, at least in part, via a Cdk2/SHP-1/β-catenin/CEACAM1 axis, and show for the first time that Cdk2 has the capacity to regulate insulin internalization.
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Affiliation(s)
- Annie Fiset
- Department of Pediatrics, CHUL-CRCHUQ, Quebec, PQ, G1V 4G2, Canada
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110
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Affiliation(s)
- Sascha Martens
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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111
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Sohda M, Misumi Y, Yamamoto A, Nakamura N, Ogata S, Sakisaka S, Hirose S, Ikehara Y, Oda K. Interaction of Golgin-84 with the COG complex mediates the intra-Golgi retrograde transport. Traffic 2010; 11:1552-66. [PMID: 20874812 DOI: 10.1111/j.1600-0854.2010.01123.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The coiled-coil Golgi membrane protein golgin-84 functions as a tethering factor for coat protein I (COPI) vesicles. Protein interaction analyses have revealed that golgin-84 interacts with another tether, the conserved oligomeric Golgi (COG) complex, through its subunit Cog7. Therefore, we explored the function of golgin-84 as the tether for COPI vesicles of intra-Golgi retrograde traffic. First, glycosylic maturation of both plasma membrane (CD44) and lysosomal (lamp1) glycoproteins was distorted in golgin-84 knockdown (KD) cells. The depletion of golgin-84 caused fragmentation of the Golgi with the mislocalization of Golgi resident proteins, resulting in the accumulation of vesicles carrying intra-Golgi soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and cis-Golgi membrane protein GPP130. Similar observations were obtained by diminution of the COG complex, suggesting a strong correlation between the two tethers. Indeed, COG complex-dependent (CCD) vesicles that accumulate in Cog3 or Cog7 KD cells carried golgin-84. Surprisingly, the interaction between golgin-84 and another candidate tethering partner CASP (CDP/cut alternatively spliced product) decreased in Cog3 KD cells. These results indicate that golgin-84 on COPI vesicles interact with the COG complex before SNARE assembly, suggesting that the interaction of golgin-84 with COG plays an important role in the tethering process of intra-Golgi retrograde vesicle traffic.
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Affiliation(s)
- Miwa Sohda
- Division of Oral Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata 951-8514, Japan
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112
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Reynders E, Foulquier F, Annaert W, Matthijs G. How Golgi glycosylation meets and needs trafficking: the case of the COG complex. Glycobiology 2010; 21:853-63. [PMID: 21112967 DOI: 10.1093/glycob/cwq179] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Protein glycosylation is one of the major biosynthetic functions occurring in the endoplasmic reticulum and Golgi compartments. It requires an amazing number of enzymes, chaperones, lectins and transporters whose actions delicately secure the fidelity of glycan structures. Over the past 30 years, glycobiologists hammered that glycan structures are not mere decorative elements but serve crucial cellular functions. This becomes dramatically illustrated by a group of mostly severe, inherited human disorders named congenital disorders of glycosylation (CDG). To date, many types of CDG have been defined genetically and most of the time the defects impair the biosynthesis, transfer and remodeling of N-glycans. Recently, the identification of the several types of CDG caused by deficiencies in the conserved oligomeric Golgi (COG) complex, a complex involved in vesicular Golgi trafficking, expanded the field of CDG but also brought novel insights in glycosylation. The molecular mechanisms underlying the complex pathway of N-glycosylation in the Golgi are far from understood. The availability of COG-deficient CDG patients and patients' cells offered a new way to study how COG, and its different subunits, could influence the Golgi N-glycosylation machinery and localization. This review summarizes the recent findings on the implication of COG in Golgi glycosylation. It highlights the need for a dynamic, finely tuned balance between anterograde and retrograde trafficking for the correct localization of Golgi enzymes to assure the stepwise maturation of N-glycan chains.
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Affiliation(s)
- Ellen Reynders
- Laboratory for Membrane Trafficking, Center for Human Genetics, KULeuven, Department for Molecular and Developmental Genetics (VIB), Leuven, Belgium
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113
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Abstract
The Golgi complex is a central processing compartment in the secretory pathway of eukaryotic cells. This essential compartment processes more than 30% of the proteins encoded by the human genome, yet we still do not fully understand how the Golgi is assembled and how proteins pass through it. Recent advances in our understanding of the molecular basis for protein transport through the Golgi and within the endocytic pathway provide clues to how this complex organelle may function and how proteins may be transported through it. Described here is a possible model for transport of cargo through a tightly stacked Golgi that involves continual fusion and fission of stable, "like" subcompartments and provides a mechanism to grow the Golgi complex from a stable progenitor, in an ordered manner.
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114
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Persico A, Cervigni RI, Barretta ML, Corda D, Colanzi A. Golgi partitioning controls mitotic entry through Aurora-A kinase. Mol Biol Cell 2010; 21:3708-21. [PMID: 20844084 PMCID: PMC2965687 DOI: 10.1091/mbc.e10-03-0243] [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: 12/27/2022] Open
Abstract
At the onset of mitosis, the Golgi complex undergoes a multistep fragmentation process that is required for its correct partitioning into the daughter cells. Inhibition of this Golgi fragmentation results in cell cycle arrest at the G2 stage, suggesting that correct inheritance of the Golgi complex is monitored by a "Golgi mitotic checkpoint." However, the molecular basis of this G2 block is not known. Here, we show that the G2-specific Golgi fragmentation stage is concomitant with centrosome recruitment and activation of the mitotic kinase Aurora-A, an essential regulator for entry into mitosis. We show that a block of Golgi partitioning impairs centrosome recruitment and activation of Aurora-A, which results in the G2 block of cell cycle progression. Overexpression of Aurora-A overrides this cell cycle block, indicating that Aurora-A is a major effector of the Golgi checkpoint. Our findings provide the basis for further understanding of the signaling pathways that coordinate organelle inheritance and cell duplication.
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Affiliation(s)
- Angela Persico
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, Chieti, Italy
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115
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Boassa D, Solan JL, Papas A, Thornton P, Lampe PD, Sosinsky GE. Trafficking and recycling of the connexin43 gap junction protein during mitosis. Traffic 2010; 11:1471-86. [PMID: 20716111 DOI: 10.1111/j.1600-0854.2010.01109.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During the cell cycle, gap junction communication, morphology and distribution of connexin43 (Cx43)-containing structures change dramatically. As cells round up in mitosis, Cx43 labeling is mostly intracellular and intercellular coupling is reduced. We investigated Cx43 distributions during mitosis both in endogenous and exogenous expressing cells using optical pulse-chase labeling, correlated light and electron microscopy, immunocytochemistry and biochemical analysis. Time-lapse imaging of green fluorescent protein (GFP)/tetracysteine tagged Cx43 (Cx43-GFP-4C) expressing cells revealed an early disappearance of gap junctions, progressive accumulation of Cx43 in cytoplasmic structures, and an unexpected subset pool of protein concentrated in the plasma membrane surrounding the midbody region in telophase followed by rapid reappearance of punctate plaques upon mitotic exit. These distributions were also observed in immuno-labeled endogenous Cx43-expressing cells. Photo-oxidation of ReAsH-labeled Cx43-GFP-4C cells in telophase confirmed that Cx43 is distributed in the plasma membrane surrounding the midbody as apparent connexons and in cytoplasmic vesicles. We performed optical pulse-chase labeling and single label time-lapse imaging of synchronized cells stably expressing Cx43 with internal tetracysteine domains through mitosis. In late telophase, older Cx43 is segregated mainly to the plasma membrane while newer Cx43 is intracellular. This older population nucleates new gap junctions permitting rapid resumption of communication upon mitotic exit.
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Affiliation(s)
- Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
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116
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Molecular mechanisms of organelle inheritance: lessons from peroxisomes in yeast. Nat Rev Mol Cell Biol 2010; 11:644-54. [PMID: 20717147 DOI: 10.1038/nrm2960] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Preserving a functional set of cytoplasmic organelles in a eukaryotic cell requires a process of accurate organelle inheritance at cell division. Studies of peroxisome inheritance in yeast have revealed that polarized transport of a subset of peroxisomes to the emergent daughter cell is balanced by retention mechanisms operating in both mother cell and bud to achieve an equitable distribution of peroxisomes between them. It is becoming apparent that some common mechanistic principles apply to the inheritance of all organelles, but at the same time, inheritance factors specific for each organelle type allow the cell to differentially and specifically control the inheritance of its different organelle populations.
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117
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118
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Wei JH, Seemann J. Spindle-dependent partitioning of the Golgi ribbon. Commun Integr Biol 2010; 2:406-7. [PMID: 19907701 DOI: 10.4161/cib.2.5.8764] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 04/17/2009] [Indexed: 11/19/2022] Open
Abstract
During mitosis, the Golgi apparatus needs to be divided into the daughter cells. To achieve successful division, the single continuous Golgi ribbon is disassembled in early mitosis into vesicular and tubular membranes, which upon segregation fuse to reform a functional Golgi complex in telophase. Although the process of Golgi division has been well described, the underlying mechanisms remain largely unknown. The observation that Golgi membranes accumulate around the spindle poles implies a role of the mitotic spindle in Golgi partitioning. By inducing asymmetrical cell division where the spindle goes into only one of the daughter cells, we have recently shown that the inheritance of a continuous Golgi ribbon critically relies on the mitotic spindle, while membranes sufficient to reassemble polarized, functional Golgi stacks are inherited independently.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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119
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Zhou Z, Sun X, Zou Z, Sun L, Zhang T, Guo S, Wen Y, Liu L, Wang Y, Qin J, Li L, Gong W, Bao S. PRMT5 regulates Golgi apparatus structure through methylation of the golgin GM130. Cell Res 2010; 20:1023-33. [PMID: 20421892 DOI: 10.1038/cr.2010.56] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Maintenance of the Golgi apparatus (GA) structure and function depends on Golgi matrix proteins. The posttranslational modification of Golgi proteins such as phosphorylation of members of the golgin and GRASP families is important for determining Golgi architecture. Some Golgi proteins including golgin-84 are also known to be methylated, but the function of golgin methylation remains unclear. Here, we show that the protein arginine methyltransferase 5 (PRMT5) localizes to the GA and forms complexes with several components involved in GA ribbon formation and vesicle tethering. PRMT5 interacts with the golgin GM130, and depletion of PRMT5 causes defects in Golgi ribbon formation. Furthermore, PRMT5 methylates N-terminal arginines in GM130, and such arginine methylation appears critical for GA ribbon formation. Our findings reveal a molecular mechanism by which PRMT5-dependent arginine methylation of GM130 controls the maintenance of GA architecture.
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Affiliation(s)
- Zhongwei Zhou
- Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology (IGDB), Chinese Academy of Sciences, Beijing 100101, China
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120
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Phosphorylation and membrane dissociation of the ARF exchange factor GBF1 in mitosis. Biochem J 2010; 427:401-12. [PMID: 20175751 DOI: 10.1042/bj20091681] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Secretory protein trafficking is arrested and the Golgi apparatus fragmented when mammalian cells enter mitosis. These changes are thought to facilitate cell-cycle progression and Golgi inheritance, and are brought about through the actions of mitotically active protein kinases. To better understand how the Golgi apparatus undergoes mitotic fragmentation we have sought to identify novel Golgi targets for mitotic kinases. We report in the present paper the identification of the ARF (ADP-ribosylation factor) exchange factor GBF1 (Golgi-specific brefeldin A-resistant guanine nucleotide-exchange factor 1) as a Golgi phosphoprotein. GBF1 is phosphorylated by CDK1 (cyclin-dependent kinase 1)-cyclin B in mitosis, which results in its dissociation from Golgi membranes. Consistent with a reduced level of GBF1 activity at the Golgi membrane there is a reduction in levels of membrane-associated GTP-bound ARF in mitotic cells. Despite the reduced levels of membrane-bound GBF1 and ARF, COPI (coat protein I) binding to the Golgi membrane appears unaffected in mitotic cells. Surprisingly, this pool of COPI is dependent upon GBF1 for its recruitment to the membrane, suggesting that a low level of GBF1 activity persists in mitosis. We propose that the phosphorylation and membrane dissociation of GBF1 and the consequent reduction in ARF-GTP levels in mitosis are important for changes in Golgi dynamics and possibly other mitotic events mediated through effectors other than the COPI vesicle coat.
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121
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Reconstitution of the cell cycle-regulated Golgi disassembly and reassembly in a cell-free system. Nat Protoc 2010; 5:758-72. [PMID: 20360770 DOI: 10.1038/nprot.2010.38] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Golgi apparatus undergoes extensive disassembly during mitosis and reassembly in post-mitotic daughter cells. This process has been mimicked in vitro by treating Golgi membranes with mitotic and interphase cytosol. To determine the minimal machinery that controls the morphological change, we have developed a defined Golgi disassembly and reassembly assay that reconstitutes this process using purified proteins instead of cytosol. Treatment of Golgi membranes with mitotic kinases and COPI coat proteins efficiently disassembles the membranes into mitotic Golgi fragments, whereas further incubation with p97 or N-ethylmaleimide-sensitive factor (two AAA ATPases involved in membrane fusion) and their cofactors, in combination with protein phosphatase PP2A, leads to reassembly of the membranes into new Golgi stacks. The whole process takes 3-4 d and is applicable for identification and determination of novel cytosolic and membrane proteins that regulate Golgi membrane dynamics in the cell cycle.
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122
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Nakamura N. Emerging new roles of GM130, a cis-Golgi matrix protein, in higher order cell functions. J Pharmacol Sci 2010; 112:255-64. [PMID: 20197635 DOI: 10.1254/jphs.09r03cr] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
GM130 is a peripheral membrane protein strongly attached to the Golgi membrane and is isolated from the detergent and salt resistant Golgi matrix. GM130 is rich in coiled-coil structures and predicted to take a rod-like shape. Together with p115, giantin, and GRASP65, GM130 facilitates vesicle fusion to the Golgi membrane as a vesicle "tethering factor". GM130 is also involved in the maintenance of the Golgi structure and plays a major role in the disassembly and reassembly of the Golgi apparatus during mitosis. Emerging evidence suggests that GM130 is involved in the control of glycosylation, cell cycle progression, and higher order cell functions such as cell polarization and directed cell migration. This creates the potential for novel Golgi-targeted drugs and treatments for various diseases including glycosylation defects, immune diseases, and cancer.
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Affiliation(s)
- Nobuhiro Nakamura
- Cell Biology, Division of Life Science, Graduate School of Natural Science and Technologies, Kanazawa University, Japan.
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123
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Abstract
In vitro assays identified the Golgi peripheral protein GRASP65 as a Golgi stacking factor that links adjacent Golgi cisternae by forming mitotically regulated trans-oligomers. These conclusions, however, require further confirmation in the cell. In this study, we showed that the first 112 amino acids at the N-terminus (including the first PDZ domain, PDZ1) of the protein are sufficient for oligomerization. Systematic electron microscopic analysis showed that the expression of non-regulatable GRASP65 mutants in HeLa cells enhanced Golgi stacking in interphase and inhibited Golgi fragmentation during mitosis. Depletion of GRASP65 by small interference RNA (siRNA) reduced the number of cisternae in the Golgi stacks; this reduction was rescued by expressing exogenous GRASP65. These results provided evidence and a molecular mechanism by which GRASP65 stacks Golgi cisternal membranes. Further experiments revealed that inhibition of mitotic Golgi disassembly by expressing non-regulatable GRASP65 mutants did not affect equal partitioning of the Golgi membranes into the daughter cells. However, it delayed mitotic entry and suppressed cell growth; this effect was diminished by dispersing the Golgi apparatus with Brefeldin A treatment prior to mitosis, suggesting that Golgi disassembly at the onset of mitosis plays a role in cell cycle progression.
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Affiliation(s)
- Danming Tang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, USA
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124
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Chen X, Simon ES, Xiang Y, Kachman M, Andrews PC, Wang Y. Quantitative proteomics analysis of cell cycle-regulated Golgi disassembly and reassembly. J Biol Chem 2010; 285:7197-207. [PMID: 20056612 DOI: 10.1074/jbc.m109.047084] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During mitosis, the stacked structure of the Golgi undergoes a continuous fragmentation process. The generated mitotic fragments are evenly distributed into the daughter cells and reassembled into new Golgi stacks. This disassembly and reassembly process is critical for Golgi biogenesis during cell division, but the underlying molecular mechanism is poorly understood. In this study, we have recapitulated this process using an in vitro assay and analyzed the proteins associated with interphase and mitotic Golgi membranes using a proteomic approach. Incubation of purified rat liver Golgi membranes with mitotic HeLa cell cytosol led to fragmentation of the membranes; subsequent treatment of these membranes with interphase cytosol allowed the reassembly of the Golgi fragments into new Golgi stacks. These membranes were then used for quantitative proteomics analyses by combining the isobaric tags for relative and absolute quantification approach with OFFGEL isoelectric focusing separation and liquid chromatography-matrix assisted laser desorption ionization-tandem mass spectrometry. In three independent experiments, a total of 1,193 Golgi-associated proteins were identified and quantified. These included broad functional categories, such as Golgi structural proteins, Golgi resident enzymes, SNAREs, Rab GTPases, cargo, and cytoskeletal proteins. More importantly, the combination of the quantitative approach with Western blotting allowed us to unveil 84 proteins with significant changes in abundance under the mitotic condition compared with the interphase condition. Among these proteins, several COPI coatomer subunits (alpha, beta, gamma, and delta) are of particular interest. Altogether, this systematic quantitative proteomic study revealed candidate proteins of the molecular machinery that control the Golgi disassembly and reassembly processes in the cell cycle.
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Affiliation(s)
- Xuequn Chen
- Department of Molecular and Integrative Physiology, The University of Michigan, Ann Arbor, Michigan 48109-1048, USA
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125
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Abstract
Newly synthesized secretory cargo molecules pass through the Golgi apparatus while resident Golgi proteins remain in the organelle. However, the pathways of membrane traffic within the Golgi are still uncertain. Most of the available data can be accommodated by the cisternal maturation model, which postulates that Golgi cisternae form de novo, carry secretory cargoes forward and ultimately disappear. The entry face of the Golgi receives material that has been exported from transitional endoplasmic reticulum sites, and the exit face of the Golgi is intimately connected with endocytic compartments. These conserved features are enhanced by cell-type-specific elaborations such as tubular connections between mammalian Golgi cisternae. Key mechanistic questions remain about the formation and maturation of Golgi cisternae, the recycling of resident Golgi proteins, the origins of Golgi compartmental identity, the establishment of Golgi architecture, and the roles of Golgi structural elements in membrane traffic.
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Affiliation(s)
- Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA.
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126
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Errico A, Deshmukh K, Tanaka Y, Pozniakovsky A, Hunt T. Identification of substrates for cyclin dependent kinases. ACTA ACUST UNITED AC 2010; 50:375-99. [DOI: 10.1016/j.advenzreg.2009.12.001] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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127
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Wei JH, Seemann J. Mitotic division of the mammalian Golgi apparatus. Semin Cell Dev Biol 2009; 20:810-6. [PMID: 19508856 DOI: 10.1016/j.semcdb.2009.03.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 03/16/2009] [Accepted: 03/16/2009] [Indexed: 10/21/2022]
Abstract
Successful cell reproduction requires faithful duplication and proper segregation of cellular contents, including not only the genome but also intracellular organelles. Since the Golgi apparatus is an essential organelle of the secretory pathway, its accurate inheritance is therefore of importance to sustain cellular function. Regulation of Golgi division and its coordination with cell cycle progression involves a series of sequential events that are subjected to a precise spatiotemporal control. Here, we summarize the current knowledge about the underlying mechanisms, the molecular players and the biological relevance of this process, particularly in mammalian cells, and discuss the unsolved problems and future perspectives opened by the recent studies.
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Affiliation(s)
- Jen-Hsuan Wei
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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128
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Kirk SJ, Cliff JM, Thomas JA, Ward TH. Biogenesis of secretory organelles during B cell differentiation. J Leukoc Biol 2009; 87:245-55. [PMID: 19889725 DOI: 10.1189/jlb.1208774] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The differentiation of B cells into Ig-secreting plasma cells requires the expansion of secretory organelles to cope with the increased cargo load. To evaluate the timeline of this process, we have quantitated the kinetics of secretory organelle expansion relative to Ig secretion and examined regulatory components of secretory transport following in vitro activation of human B lymphocytes. Unstimulated B cells contain minimal endomembranes. After activation, ER membrane induction appears as tightly packed spherical structures of 0.5-1 mum diameter concentrated in a juxtanuclear position. When the cells differentiate into plasmablasts, there is dramatic cell-size increase, but the ER remains concentrated close to the nucleus and only later fills the entire cell. In sharp contrast, previous studies in other cell types have found that the ER expands in synchrony with increasing cell size during interphase, by extension of ER tubules under the PM. In this study, the Golgi remains consistently as a single juxtanuclear structure but linearly expands sixfold in volume during B cell activation. Furthermore, following active cell proliferation, ER exit sites proliferate rapidly, increasing almost fourfold in number, in parallel with a sharp increase in Ig secretion. These findings demonstrate that the control of organelle biogenesis and expansion in primary human B cells are differentially regulated by cargo flux caused by Ig synthesis.
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Affiliation(s)
- Semra J Kirk
- Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
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129
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Persico A, Cervigni RI, Barretta ML, Colanzi A. Mitotic inheritance of the Golgi complex. FEBS Lett 2009; 583:3857-62. [PMID: 19879264 DOI: 10.1016/j.febslet.2009.10.077] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 10/26/2009] [Accepted: 10/27/2009] [Indexed: 12/13/2022]
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130
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Papanikou E, Glick BS. The yeast Golgi apparatus: insights and mysteries. FEBS Lett 2009; 583:3746-51. [PMID: 19879270 DOI: 10.1016/j.febslet.2009.10.072] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 10/26/2009] [Accepted: 10/27/2009] [Indexed: 11/28/2022]
Abstract
The Golgi apparatus is known to modify and sort newly synthesized secretory proteins. However, fundamental mysteries remain about the structure, operation, and dynamics of this organelle. Important insights have emerged from studying the Golgi in yeasts. For example, yeasts have provided direct evidence for Golgi cisternal maturation, a mechanism that is likely to be broadly conserved. Here, we highlight features of the yeast Golgi as well as challenges that lie ahead.
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Affiliation(s)
- Effrosyni Papanikou
- The University of Chicago, Molecular Genetics and Cell Biology, 920 East 58th St., Chicago, IL 60637, USA
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131
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Kondylis V, Rabouille C. The Golgi apparatus: lessons from Drosophila. FEBS Lett 2009; 583:3827-38. [PMID: 19800333 DOI: 10.1016/j.febslet.2009.09.048] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 09/10/2009] [Accepted: 09/26/2009] [Indexed: 11/19/2022]
Abstract
Historically, Drosophila has been a model organism for studying molecular and developmental biology leading to many important discoveries in this field. More recently, the fruit fly has started to be used to address cell biology issues including studies of the secretory pathway, and more specifically on the functional integrity of the Golgi apparatus. A number of advances have been made that are reviewed below. Furthermore, with the development of RNAi technology, Drosophila tissue culture cells have been used to perform genome-wide screens addressing similar issues. Last, the Golgi function has been involved in specific developmental processes, thus shedding new light on the functions of a number of Golgi proteins.
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Affiliation(s)
- Vangelis Kondylis
- Cell Microscopy Centre, Department of Cell Biology, UMC Utrecht, AZU H02.313, Heidelberglaan 100, Utrecht, The Netherlands.
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132
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Sevova ES, Bangs JD. Streamlined architecture and glycosylphosphatidylinositol-dependent trafficking in the early secretory pathway of African trypanosomes. Mol Biol Cell 2009; 20:4739-50. [PMID: 19759175 DOI: 10.1091/mbc.e09-07-0542] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The variant surface glycoprotein (VSG) of bloodstream form Trypanosoma brucei (Tb) is a critical virulence factor. The VSG glycosylphosphatidylinositol (GPI)-anchor strongly influences passage through the early secretory pathway. Using a dominant-negative mutation of TbSar1, we show that endoplasmic reticulum (ER) exit of secretory cargo in trypanosomes is dependent on the coat protein complex II (COPII) machinery. Trypanosomes have two orthologues each of the Sec23 and Sec24 COPII subunits, which form specific heterodimeric pairs: TbSec23.1/TbSec24.2 and TbSec23.2/TbSec24.1. RNA interference silencing of each subunit is lethal but has minimal effects on trafficking of soluble and transmembrane proteins. However, silencing of the TbSec23.2/TbSec24.1 pair selectively impairs ER exit of GPI-anchored cargo. All four subunits colocalize to one or two ER exit sites (ERES), in close alignment with the postnuclear flagellar adherence zone (FAZ), and closely juxtaposed to corresponding Golgi clusters. These ERES are nucleated on the FAZ-associated ER. The Golgi matrix protein Tb Golgi reassembly stacking protein defines a region between the ERES and Golgi, suggesting a possible structural role in the ERES:Golgi junction. Our results confirm a selective mechanism for GPI-anchored cargo loading into COPII vesicles and a remarkable degree of streamlining in the early secretory pathway. This unusual architecture probably maximizes efficiency of VSG transport and fidelity in organellar segregation during cytokinesis.
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Affiliation(s)
- Elitza S Sevova
- Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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133
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Judson BL, Brown WJ. Assembly of an intact Golgi complex requires phospholipase A2 (PLA2) activity, membrane tubules, and dynein-mediated microtubule transport. Biochem Biophys Res Commun 2009; 389:473-7. [PMID: 19747452 DOI: 10.1016/j.bbrc.2009.08.173] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 08/31/2009] [Indexed: 12/23/2022]
Abstract
Previous studies have shown that treatment of mammalian cells with phospholipase A(2) (PLA(2)) antagonists cause the normally interconnected Golgi ribbon to break up into large fragments of stacked Golgi cisternae ("mini-stacks") that remain located in the juxtanuclear region. Using the reversible PLA(2) antagonist, ONO-RS-082 (ONO) and live-cell, time-lapse microscopy to image the Golgi reassembly process, we found that Golgi mini-stacks underwent a burst of membrane tubule formation following washout of ONO: before washout only 4.3+/-3.8 tubules/cell/10 min were formed, whereas after washout 29.9+/-11.9 tubules/cell/10 min formed. These membranes tubules formed bridges between physically separate mini-stacks, thus mediating their coalescence into intact Golgi ribbons. Formation of inter-stack tubules and an intact Golgi ribbon was also facilitated by microtubules because treatment with nocodazole significantly inhibited both processes. This microtubule-dependent process was also dependent on dynein because the dynein inhibitor nordihydroguaiaretic acid (NDGA) inhibited reassembly. These studies show that a late stage of Golgi assembly occurs via membrane tubules, whose formation is dependent on PLA(2) activity and microtubules. Considering these results together, we concluded that the maintenance and assembly of normal Golgi architecture is dependent on the PLA(2)-mediated, dynamic formation of inter-Golgi membrane tubules.
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Affiliation(s)
- Bret L Judson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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134
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Miller PM, Folkmann AW, Maia ARR, Efimova N, Efimov A, Kaverina I. Golgi-derived CLASP-dependent microtubules control Golgi organization and polarized trafficking in motile cells. Nat Cell Biol 2009; 11:1069-80. [PMID: 19701196 PMCID: PMC2748871 DOI: 10.1038/ncb1920] [Citation(s) in RCA: 230] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 05/22/2009] [Indexed: 01/10/2023]
Abstract
Microtubules are indispensable for Golgi complex assembly and maintenance, which are integral parts of cytoplasm organization during interphase in mammalian cells. Here, we show that two discrete microtubule subsets drive two distinct, yet simultaneous, stages of Golgi assembly. In addition to the radial centrosomal microtubule array, which positions the Golgi in the centre of the cell, we have identified a role for microtubules that form at the Golgi membranes in a manner dependent on the microtubule regulators CLASPs. These Golgi-derived microtubules draw Golgi ministacks together in tangential fashion and are crucial for establishing continuity and proper morphology of the Golgi complex. We propose that specialized functions of these two microtubule arrays arise from their specific geometries. Further, we demonstrate that directional post-Golgi trafficking and cell migration depend on Golgi-associated CLASPs, suggesting that correct organization of the Golgi complex by microtubules is essential for cell polarization and motility.
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Affiliation(s)
- Paul M Miller
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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135
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Maekawa M, Inoue T, Kobuna H, Nishimura T, Gengyo-Ando K, Mitani S, Arai H. Functional analysis of GS28, an intra-Golgi SNARE, in Caenorhabditis elegans. Genes Cells 2009; 14:1003-13. [PMID: 19624756 DOI: 10.1111/j.1365-2443.2009.01325.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intra-Golgi retrograde transport is assumed to maintain Golgi function by recycling Golgi-resident proteins to younger cisternae in the progression of entire Golgi stack from cis to trans. GS28 (Golgi SNARE of 28 kDa, also known as GOS28) is a Golgi-localized SNARE protein and has been implicated in intra-Golgi retrograde transport. However, the in vivo functions of GS28, and consequently, the roles of the intra-Golgi retrograde transport in animal development are largely unknown. In this study, we generated deletion mutants of Caenorhabditis elegans GS28 and performed a synthetic lethal RNAi screen using GS28 mutants. We found that another Golgi-localized SNARE, Ykt6, functions cooperatively with GS28 in embryonic development. During post-embryonic development, GS28 mutants exhibited reduced seam cell numbers and a missing ray phenotype under Ykt6 knockdown conditions, suggesting that cell proliferation and/or differentiation of stem cell-like seam cells are impaired in GS28- and Ykt6-depleted worms. We also demonstrated that GS28 and Ykt6 act redundantly for the proper expression of Golgi-resident proteins in adult intestinal cells. This study reveals the in vivo importance of the Golgi-localized SNAREs GS28 and Ykt6.
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Affiliation(s)
- Masashi Maekawa
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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136
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Cobbold C, Coventry J, Ponnambalam S, Monaco AP. Actin and microtubule regulation ofTrans-Golgi network architecture, and copper-dependent protein transport to the cell surface. Mol Membr Biol 2009; 21:59-66. [PMID: 14668139 DOI: 10.1080/096870310001607350] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The Menkes disease ATPase (MNK) is a copper transporter that localizes to the mammalian trans-Golgi network (TGN) and shows substantial co-localization wih a ubiquitous TGN resident protein and marker, TGN46. We tested our hypothesis that these two TGN residents and integral membrane proteins are localized to biochemically distinct TGN sub-compartments using constitutively active mutant proteins and drugs that disrupt membrane traffic, lumenal pH and the cellular cytoskeleton. The pH-disrupting agent, monensin, causes MNK to be more diffusely distributed with partial separation of staining patterns for these two TGN residents. Expression of a constitutively active Rho-kinase (ROCK-KIN), which causes formation of juxta-nuclear astral actin arrays, also effects separation of MNK and TGN46 staining patterns. Treatment of ROCK-KIN expressing cells with latrunculin B, an actin-depolymerizing agent, causes complete overlap of MNK and TGN46 staining patterns with concomitant disappearance of polymerized actin. When microtubules are depolymerized in ROCK-KIN expressing cells by nocodazole, both MNK and TGN46 are found in puncate structures throughout the cell. However, a substantial proportion of MNK is still found in a juxta-nuclear location in contrast to TGN46. Actin distribution in these cells reveals that juxta-nuclear MNK is distinct to the astral actin clusters in ROCK-KIN expressing cells where the microtubules were depolymerized. The TGN to cell-surface transport of MNK requires both actin and microtubules networks, whilst the constitutive trafficking of proteins is independent of actin. Taken together, our findings indicate that at least two TGN sub-domains are regulated by separate cytoskeletal dynamics involving actin and tubulin.
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Affiliation(s)
- Christian Cobbold
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, 0X3 7BN Oxford, UK
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137
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Morriswood B, He CY, Sealey-Cardona M, Yelinek J, Pypaert M, Warren G. The bilobe structure of Trypanosoma brucei contains a MORN-repeat protein. Mol Biochem Parasitol 2009; 167:95-103. [PMID: 19445968 DOI: 10.1016/j.molbiopara.2009.05.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 05/04/2009] [Accepted: 05/05/2009] [Indexed: 11/16/2022]
Abstract
The Golgi of the kinetoplastid parasite Trypanosoma brucei is closely apposed to a bilobe structure containing TbCentrin2 and TbCentrin4 in procyclic cells. However, both are additionally localized to the basal bodies. Here we report the characterization of a membrane occupation and recognition nexus (MORN)-repeat protein, TbMORN1, present at the bilobe but not at the basal body. The anterior part of the TbMORN1 structure partially overlapped with the flagellar attachment zone while the posterior part overlapped with the flagellar pocket. Depletion studies using RNAi showed that there was a modest growth inhibition in procyclic cells but lethality in bloodstream cells, showing that it is an essential protein in the bloodstream form of the organism. TbMORN1 appears to be a useful marker for the bilobe in T. brucei.
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Affiliation(s)
- Brooke Morriswood
- Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
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138
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Abstract
Golgi duplication in the protozoan parasite Trypanosoma brucei has been tracked using serial thin section three-dimensional reconstructions of transmission electron micrographs. The old Golgi maintains a constant size (approximately 0.060 microm(3)) throughout the cell cycle. A morphologically identifiable new Golgi appears at approximately 0.20 of the cell cycle (defined by the size of the nucleus and lasting about 9 h) and grows from approximately 0.018 microm(3) until it is the same size as the old Golgi (by approximately 0.55 of the cell cycle). Morphologically identifiable late Golgi appear at approximately 0.58 of the cell cycle, but their volume ( approximately 0.036 microm(3)) did not change significantly. Cryoimmunoelectron microscopy was used to identify candidates for the earliest new Golgi structures, and these comprised clusters of vesicles containing Golgi reassembly stacking protein (GRASP) near an endoplasmic reticulum exit site. These results, combined with earlier fluorescence data, suggest that the new Golgi begins functioning before cisternal stacks are formed.
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Affiliation(s)
- Jordan T Yelinek
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
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139
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Beck R, Adolf F, Weimer C, Bruegger B, Wieland FT. ArfGAP1 Activity and COPI Vesicle Biogenesis. Traffic 2009; 10:307-15. [DOI: 10.1111/j.1600-0854.2008.00865.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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140
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Hölzenspies JJ, Stoorvogel W, Colenbrander B, Roelen BAJ, Gutknecht DR, van Haeften T. CDC2/SPDY transiently associates with endoplasmic reticulum exit sites during oocyte maturation. BMC DEVELOPMENTAL BIOLOGY 2009; 9:8. [PMID: 19187565 PMCID: PMC2644288 DOI: 10.1186/1471-213x-9-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/03/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Mammalian oocytes acquire competence to be fertilized during meiotic maturation. The protein kinase CDC2 plays a pivotal role in several key maturation events, in part through controlled changes in CDC2 localization. Although CDC2 is involved in initiation of maturation, a detailed analysis of CDC2 localization at the onset of maturation is lacking. In this study, the subcellular distribution of CDC2 and its regulatory proteins cyclin B and SPDY in combination with several organelle markers at the onset of pig oocyte maturation has been investigated. RESULTS Our results demonstrate that CDC2 transiently associates with a single domain, identified as a cluster of endoplasmic reticulum (ER) exit sites (ERES) by the presence of SEC23, in the cortex of maturing porcine oocytes prior to germinal vesicle break down. Inhibition of meiosis resumption by forskolin treatment prevented translocation of CDC2 to this ERES cluster. Phosphorylated GM130 (P-GM130), which is a marker for fragmented Golgi, localized to ERES in almost all immature oocytes and was not affected by forskolin treatment. After removal of forskolin from the culture media, the transient translocation of CDC2 to ERES was accompanied by a transient dispersion of P-GM130 into the ER suggesting a role for CDC2 in redistributing Golgi components that have collapsed into ERES further into the ER during meiosis. Finally, we show that SPDY, rather than cyclin B, colocalizes with CDC2 at ERES, suggesting a role for the CDC2/SPDY complex in regulating the secretory pathway during oocyte maturation. CONCLUSION Our data demonstrate the presence of a novel structure in the cortex of porcine oocytes that comprises ERES and transiently accumulates CDC2 prior to germinal vesicle breakdown. In addition, we show that SPDY, but not cyclin B, localizes to this ERES cluster together with CDC2.
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Affiliation(s)
- Jurriaan J Hölzenspies
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Willem Stoorvogel
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Ben Colenbrander
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Bernard AJ Roelen
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Dagmar R Gutknecht
- Department of Reproductive Medicine, University Medical Centre, Utrecht, the Netherlands
| | - Theo van Haeften
- Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
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141
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Chapter 3. New insights into plant vacuolar structure and dynamics. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 277:103-35. [PMID: 19766968 DOI: 10.1016/s1937-6448(09)77003-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant vacuole is a multifunctional organelle and is essential for plant development and growth. The most distinctive feature of the plant vacuole is its size, which usually occupies over 80-90% of the cell volume in well-developed somatic cells, and is therefore highly involved in cell growth and plant body size. Recent progress in the visualization of the vacuole, together with developments in image analysis, has revealed the highly organized and complex morphology of the vacuole, as well as its dynamics. The plant vacuolar membrane (VM) forms not only a typically large vacuole but also other structures, such as tubular structures, transvacuolar strands, bulbs, and sheets. In higher plant cells, actin microfilaments are mainly located near the VM and are involved in vacuolar shape changes with the actin-myosin systems. Most recently, microtubule-dependent regulation of vacuolar structures in moss plant cells was reported, suggesting a diversity of mechanisms regulating vacuolar morphogenesis.
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142
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Field MC, Lumb JH, Adung'a VO, Jones NG, Engstler M. Chapter 1 Macromolecular Trafficking and Immune Evasion in African Trypanosomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:1-67. [DOI: 10.1016/s1937-6448(09)78001-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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143
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Tseng SY, Waite JC, Liu M, Vardhana S, Dustin ML. T cell-dendritic cell immunological synapses contain TCR-dependent CD28-CD80 clusters that recruit protein kinase C theta. THE JOURNAL OF IMMUNOLOGY 2008; 181:4852-63. [PMID: 18802089 DOI: 10.4049/jimmunol.181.7.4852] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Short-lived TCR microclusters and a longer-lived protein kinase Ctheta-focusing central supramolecular activation cluster (cSMAC) have been defined in model immunological synapses (IS). In different model systems, CD28-mediated costimulatory interactions have been detected in microclusters, the cSMAC, or segregated from the TCR forming multiple distinct foci. The relationship between TCR and costimulatory molecules in the physiological IS of T cell-dendritic cell (DC) is obscure. To study the dynamic relationship of CD28-CD80 and TCR interactions in the T cell-DC IS during Ag-specific T cell activation, we generated CD80-eCFP mice using bacterial artificial chromosome transgenic technology. In splenic DCs, endogenous CD80 and CD80-eCFP localized to plasma membrane and Golgi apparatus, and CD80-eCFP was functional in vivo. In the OT-II T cell-DC IS, multiple segregated TCR, CD80, and LFA-1 clusters were detected. In the T cell-DC synapse CD80 clusters were colocalized with CD28 and PKCtheta, a characteristic of the cSMAC. Acute blockade of TCR signaling with anti-MHC Ab resulted in a rapid reduction in Ca(2+) signaling and the number and size of the CD80 clusters, a characteristic of TCR microclusters. Thus, the T cell-DC interface contains dynamic costimulatory foci that share characteristics of microclusters and cSMACs.
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Affiliation(s)
- Su-Yi Tseng
- Program in Molecular Pathogenesis, Helen L. and Martin S. Kimmel Center for Biology and Medicine of the Skirball Institute of Biomolecular Medicine and Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
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144
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Plk3 interacts with and specifically phosphorylates VRK1 in Ser342, a downstream target in a pathway that induces Golgi fragmentation. Mol Cell Biol 2008; 29:1189-201. [PMID: 19103756 DOI: 10.1128/mcb.01341-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Golgi fragmentation is a process that is necessary to allow its redistribution into daughter cells during mitosis, a process controlled by serine-threonine kinases. This Golgi fragmentation is activated by MEK1 and Plk3. Plk3 is a kinase that is a downstream target in the Golgi fragmentation pathway induced by MEK1 or by nocodazole. In this work, we have identified that Plk3 and VRK1 are two consecutive steps in this signaling pathway. Plk3 interacts with VRK1, forming a stable complex detected by reciprocal immunoprecipitations and pull-down assays; VRK1 colocalizes with giantin in the Golgi apparatus, as Plk3 also does, forming clearly detectable granules. VRK1 does not phosphorylate Plk3, but Plk3 phosphorylates the C-terminal region of VRK1 in Ser342. VRK1 with substitutions in S342 is catalytically active but blocks Golgi fragmentation, indicating that its specific phosphorylation is necessary for this process. The induction of Golgi fragmentation by MEK1 and Plk3 can be inhibited by kinase-dead VRK1, the knockdown of VRK1 by siVRK1, kinase-dead Plk3, or PD98059, a MEK1 inhibitor. The Plk3-VRK1 kinase module might represent two consecutive steps of a signaling cascade that participates in the regulation of Golgi fragmentation.
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145
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Heuer D, Rejman Lipinski A, Machuy N, Karlas A, Wehrens A, Siedler F, Brinkmann V, Meyer TF. Chlamydia causes fragmentation of the Golgi compartment to ensure reproduction. Nature 2008; 457:731-5. [PMID: 19060882 DOI: 10.1038/nature07578] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 10/22/2008] [Indexed: 01/30/2023]
Abstract
The obligate intracellular bacterium Chlamydia trachomatis survives and replicates within a membrane-bound vacuole, termed the inclusion, which intercepts host exocytic pathways to obtain nutrients. Like many other intracellular pathogens, C. trachomatis has a marked requirement for host cell lipids, such as sphingolipids and cholesterol, produced in the endoplasmic reticulum and the Golgi apparatus. However, the mechanisms by which intracellular pathogens acquire host cell lipids are not well understood. In particular, no host cell protein responsible for transporting Golgi-derived lipids to the chlamydial inclusions has yet been identified. Here we show that Chlamydia infection in human epithelial cells induces Golgi fragmentation to generate Golgi ministacks surrounding the bacterial inclusion. Ministack formation is triggered by the proteolytic cleavage of the Golgi matrix protein golgin-84. Inhibition of golgin-84 truncation prevents Golgi fragmentation, causing a block in lipid acquisition and maturation of C. trachomatis. Golgi fragmentation by means of RNA-interference-mediated knockdown of distinct Golgi matrix proteins before infection enhances bacterial maturation. Our data functionally connect bacteria-induced golgin-84 cleavage, Golgi ministack formation, lipid acquisition and intracellular pathogen growth. We show that C. trachomatis subverts the structure and function of an entire host cell organelle for its own advantage.
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Affiliation(s)
- Dagmar Heuer
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Charitéplatz 1, 10117 Berlin, Germany
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146
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Mukherjee S, Shields D. Nuclear import is required for the pro-apoptotic function of the Golgi protein p115. J Biol Chem 2008; 284:1709-17. [PMID: 19028683 DOI: 10.1074/jbc.m807263200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During apoptosis the Golgi apparatus undergoes irreversible fragmentation. In part, this results from caspase-mediated cleavage of several high molecular weight coiled-coil proteins, termed golgins. These include GM130, golgin 160, and the Golgi vesicle tethering protein p115, whose caspase cleavage generates a C-terminal fragment (CTF) of 205 residues. Here we demonstrate that early during apoptosis, following the rapid cleavage of p115, endogenous CTF translocated to the cell nucleus and its nuclear import was required to enhance the apoptotic response. Expression of a series of deletion constructs identified a putative alpha-helical region of 26 amino acids, whose expression alone was sufficient to induce apoptosis; deletion of these 26 residues from the CTF diminished its proapoptotic activity. This region contains several potential SUMOylation sites and co-expression of SUMO together with the SUMO ligase, UBC9, resulted in SUMOylation of the p115 CTF. Significantly, when cells were treated with drugs that induce apoptosis, SUMOylation enhanced the efficiency of p115 cleavage and the kinetics of apoptosis. A construct in which a nuclear export signal was fused to the N terminus of p115 CTF accumulated in the cytoplasm and surprisingly, its expression did not induce apoptosis. In contrast, treatment of cells expressing this chimera with the antibiotic leptomycin induced its translocation into the nucleus and resulted in the concomitant induction of apoptosis. These results demonstrate that nuclear import of the p115 CTF is required for it to stimulate the apoptotic response and suggest that its mode of action is confined to the nucleus.
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Affiliation(s)
- Shaeri Mukherjee
- Department of Developmental, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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147
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Zhong W. Timing cell-fate determination during asymmetric cell divisions. Curr Opin Neurobiol 2008; 18:472-8. [PMID: 18983918 DOI: 10.1016/j.conb.2008.10.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 10/19/2008] [Accepted: 10/22/2008] [Indexed: 01/05/2023]
Abstract
From invertebrates to mammals, cell-cycle progression during an asymmetric cell division is accompanied by precisely timed redistribution of cell-fate determinants so that they segregate asymmetrically to enable the two daughter cells to choose different fates. Interestingly, studies on how cell fates are specified in such divisions reveal that the same fate determinants can be reiteratively used to specify a variety of cell types through multiple rounds of cell divisions or to exert seemingly contradictory effects on cell proliferation and differentiation. Here I summarize the molecular mechanisms governing asymmetric cell division and review recent findings pointing to a novel mechanism for coupling intracellular signaling and cell-cycle progression. This mechanism uses changes in the morphology, subcellular distribution, and molecular composition of cellular organelles like the Golgi apparatus and centrosomes, which not only accompany the progression of cell cycle to activate but also temporally constrain the activity of fate determinants during asymmetric cell divisions.
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Affiliation(s)
- Weimin Zhong
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
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148
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Jackson-Hayes L, Hill TW, Loprete DM, Fay LM, Gordon BS, Nkashama SA, Patel RK, Sartain CV. Two GDP-mannose transporters contribute to hyphal form and cell wall integrity in Aspergillus nidulans. MICROBIOLOGY-SGM 2008; 154:2037-2047. [PMID: 18599832 DOI: 10.1099/mic.0.2008/017483-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In order to identify novel genes affecting cell wall integrity, we have generated mutant strains of the filamentous fungus Aspergillus nidulans that show hypersensitivity to the chitin-binding agent Calcofluor White (CFW). Affected loci are designated cal loci. The phenotype of one of these alleles, calI11, also includes shortened hyphal compartments and increased density of branching in the absence of CFW, as well as reduced staining of cell walls by the lectin FITC-Concanavalin A (ConA), which has strong binding affinity for mannosyl residues. We have identified two A. nidulans genes (AN8848.3 and AN9298.3, designated gmtA and gmtB, respectively) that complement all aspects of the phenotype. Both genes show strong sequence similarity to GDP-mannose transporters (GMTs) of Saccharomyces and other yeasts. Sequencing of gmtA from the calI11 mutant strain reveals a G to C mutation at position 943, resulting in a predicted alanine to proline substitution at amino acid position 315 within a region that is highly conserved among other fungi. No mutations were observed in the mutant strain's allele of gmtB. Meiotic mapping demonstrated a recombination frequency of under 1 % between the calI locus and the phenA locus (located approximately 9.5 kb from AN8848.3), confirming that gmtA and calI are identical. A GmtA-GFP chimera exhibits a punctate distribution pattern, consistent with that shown by putative Golgi markers in A. nidulans. However, this distribution did not overlap with that of the putative Golgi equivalent marker CopA-monomeric red fluorescent protein (mRFP), which may indicate that the physically separated Golgi-equivalent organelles of A. nidulans represent physiologically distinct counterparts of the stacked cisternae of plants and animals. These findings demonstrate that gmtA and gmtB play roles in cell wall metabolism in A. nidulans similar to those previously reported for GMTs in yeasts.
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Affiliation(s)
| | - Terry W Hill
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Darlene M Loprete
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Lauren M Fay
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Barbara S Gordon
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Sonia A Nkashama
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Ravi K Patel
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
| | - Caroline V Sartain
- Departments of Chemistry and Biology, Rhodes College, Memphis, TN 38112, USA
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149
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Bisel B, Wang Y, Wei JH, Xiang Y, Tang D, Miron-Mendoza M, Yoshimura SI, Nakamura N, Seemann J. ERK regulates Golgi and centrosome orientation towards the leading edge through GRASP65. ACTA ACUST UNITED AC 2008; 182:837-43. [PMID: 18762583 PMCID: PMC2528584 DOI: 10.1083/jcb.200805045] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Directed cell migration requires the orientation of the Golgi and centrosome toward the leading edge. We show that stimulation of interphase cells with the mitogens epidermal growth factor or lysophosphatidic acid activates the extracellular signal-regulated kinase (ERK), which phosphorylates the Golgi structural protein GRASP65 at serine 277. Expression of a GRASP65 Ser277 to alanine mutant or a GRASP65 1-201 truncation mutant, neither of which can be phosphorylated by ERK, prevents Golgi orientation to the leading edge in a wound assay. We show that phosphorylation of GRASP65 with recombinant ERK leads to the loss of GRASP65 oligomerization and causes Golgi cisternal unstacking. Furthermore, preventing Golgi polarization by expressing mutated GRASP65 inhibits centrosome orientation, which is rescued upon disassembly of the Golgi structure by brefeldin A. We conclude that Golgi remodeling, mediated by phosphorylation of GRASP65 by ERK, is critical for the establishment of cell polarity in migrating cells.
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Affiliation(s)
- Blaine Bisel
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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150
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Struck NS, Herrmann S, Langer C, Krueger A, Foth BJ, Engelberg K, Cabrera AL, Haase S, Treeck M, Marti M, Cowman AF, Spielmann T, Gilberger TW. Plasmodium falciparumpossesses two GRASP proteins that are differentially targeted to the Golgi complex via a higher- and lower-eukaryote-like mechanism. J Cell Sci 2008; 121:2123-9. [DOI: 10.1242/jcs.021154] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum, the causative agent of malaria, relies on a complex protein-secretion system for protein targeting into numerous subcellular destinations. Recently, a homologue of the Golgi re-assembly stacking protein (GRASP) was identified and used to characterise the Golgi organisation in this parasite. Here, we report on the presence of a splice variant that leads to the expression of a GRASP isoform. Although the first GRASP protein (GRASP1) relies on a well-conserved myristoylation motif, the variant (GRASP2) displays a different N-terminus, similar to GRASPs found in fungi. Phylogenetic analyses between GRASP proteins of numerous taxa point to an independent evolution of the unusual N-terminus that could reflect unique requirements for Golgi-dependent protein sorting and organelle biogenesis in P. falciparum. Golgi association of GRASP2 depends on the hydrophobic N-terminus that resembles a signal anchor, leading to a unique mode of Golgi targeting and membrane attachment.
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Affiliation(s)
- Nicole S. Struck
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Susann Herrmann
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Christine Langer
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Andreas Krueger
- German Armed Forces, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Bernardo J. Foth
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Klemens Engelberg
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Ana L. Cabrera
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Silvia Haase
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Moritz Treeck
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Matthias Marti
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
| | - Alan F. Cowman
- The Walter and Eliza Hall Institute of Medical Research, Melbourne 3050, Australia
| | - Tobias Spielmann
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
| | - Tim W. Gilberger
- Bernhard Nocht Institute for Tropical Medicine, Malaria II, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
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