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Small GTPases 2012Small GTPases regulate a wide range of homeostatic processes such as cytoskeletal dynamics, organelle homeostasis, cell migration and vesicle trafficking, as well as in... (Review)
Review
Small GTPases regulate a wide range of homeostatic processes such as cytoskeletal dynamics, organelle homeostasis, cell migration and vesicle trafficking, as well as in pathologic conditions such as carcinogenesis and metastatic spreading. Therefore, it is important to understand the regulation of small GTPase signaling, but this is complicated by the fact that crosstalk exists between different GTPase families and that we have to understand how they signal in time and space. The Golgi apparatus represents a hub for several signaling molecules and its importance in this field is constantly increasing. In this review we will discuss small GTPases signaling at the Golgi apparatus. Then, we will highlight recent work that contributed to a better understanding of crosstalk between different small GTPase families, with a special emphasis on their crosstalk at the Golgi apparatus. Finally, we will give a brief overview of available methods and tools to investigate spatio-temporal small GTPase crosstalk.
Topics: Animals; Biosensing Techniques; Golgi Apparatus; Humans; Monomeric GTP-Binding Proteins; Signal Transduction; Up-Regulation
PubMed: 22790194
DOI: 10.4161/sgtp.19842 -
Cell Death and Differentiation Aug 2019LC3 is a protein that can associate with autophagosomes, autolysosomes, and phagosomes. Here, we show that LC3 can also redistribute toward the damaged Golgi apparatus...
LC3 is a protein that can associate with autophagosomes, autolysosomes, and phagosomes. Here, we show that LC3 can also redistribute toward the damaged Golgi apparatus where it clusters with SQSTM1/p62 and lysosomes. This organelle-specific relocation, which did not involve the generation of double-membraned autophagosomes, could be observed after Golgi damage was induced by various strategies, namely (i) laser-induced localized cellular damage, (ii) local expression of peroxidase and exposure to peroxide and diaminobenzidine, (iii) treatment with the Golgi-tropic photosensitizer redaporfin and light, (iv) or exposure to the Golgi-tropic anticancer peptidomimetic LTX-401. Mechanistic exploration led to the conclusion that both reactive oxygen species-dependent and -independent Golgi damage induces a similar phenotype that depended on ATG5 yet did not depend on phosphatidylinositol-3-kinase catalytic subunit type 3 and Beclin-1. Interestingly, knockout of ATG5 sensitized cells to Golgi damage-induced cell death, suggesting that the pathway culminating in the relocation of LC3 to the damaged Golgi may have a cytoprotective function.
Topics: Antineoplastic Agents; Cell Death; Golgi Apparatus; Green Fluorescent Proteins; HeLa Cells; Humans; Microtubule-Associated Proteins; Tumor Cells, Cultured; beta-Alanine
PubMed: 30349077
DOI: 10.1038/s41418-018-0221-5 -
Free Radical Biology & Medicine Apr 2022Since the first fluorescent proteins (FPs) were identified and isolated over fifty years ago, FPs have become commonplace yet indispensable tools for studying the... (Review)
Review
Since the first fluorescent proteins (FPs) were identified and isolated over fifty years ago, FPs have become commonplace yet indispensable tools for studying the constitutive secretory pathway in live cells. At the same time, genetically encoded chemical tags have provided a new use for much older fluorescent dyes. Innovation has also produced several specialized methods to allow synchronous release of cargo proteins from the endoplasmic reticulum (ER), enabling precise characterization of sequential trafficking steps in the secretory pathway. Without the constant innovation of the researchers who design these tools to control, image, and quantitate protein secretion, major discoveries about ER-to-Golgi transport and later stages of the constitutive secretory pathway would not have been possible. We review many of the tools and tricks, some 25 years old and others brand new, that have been successfully implemented to study ER-to-Golgi transport in intact and living cells.
Topics: Endoplasmic Reticulum; Golgi Apparatus; Protein Transport
PubMed: 35272000
DOI: 10.1016/j.freeradbiomed.2022.03.004 -
Glycobiology Dec 2011Cell surface lectin staining, examination of Golgi glycosyltransferases stability and localization, and matrix-assisted laser desorption ionization-time of flight...
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.
Topics: Adaptor Proteins, Vesicular Transport; Animals; CHO Cells; Cells, Cultured; Cricetinae; Evolution, Molecular; Glycosylation; Glycosyltransferases; Golgi Apparatus; HeLa Cells; Humans
PubMed: 21421995
DOI: 10.1093/glycob/cwr028 -
The Journal of Histochemistry and... Dec 2012Heparan sulfate is perhaps the most complex polysaccharide known from animals. The basic repeating disaccharide is extensively modified by sulfation and uronic acid... (Review)
Review
Heparan sulfate is perhaps the most complex polysaccharide known from animals. The basic repeating disaccharide is extensively modified by sulfation and uronic acid epimerization. Despite this, the fine structure of heparan sulfate is remarkably consistent with a particular cell type. This suggests that the synthesis of heparan sulfate is tightly controlled. Although genomics has identified the enzymes involved in glycosaminoglycan synthesis in a number of vertebrates and invertebrates, the regulation of the process is not understood. Moreover, the localization of the various enzymes in the Golgi apparatus has not been carried out in a detailed way using high-resolution microscopy. We have begun this process, using well-known markers for the various Golgi compartments, coupled with the use of characterized antibodies and cDNA expression. Laser scanning confocal microscopy coupled with line scanning provides high-quality resolution of the distribution of enzymes. The EXT2 protein, which when combined as heterodimers with EXT1 comprises the major polymerase in heparan sulfate synthesis, has been studied in depth. All the data are consistent with a cis-Golgi distribution and provide a starting point to establish whether all the enzymes are clustered in a multimolecular complex or are distributed through the various compartments of the Golgi apparatus.
Topics: Animals; Endoplasmic Reticulum; Golgi Apparatus; Heparitin Sulfate; Humans; Immunohistochemistry; Microscopy, Confocal; Multienzyme Complexes
PubMed: 22899865
DOI: 10.1369/0022155412460056 -
Traffic (Copenhagen, Denmark) Sep 2000The new millennium coincides within 1 year of Camillo Golgi's centennial celebrations. It is quite remarkable that the structure and formation of this organelle is as... (Review)
Review
The new millennium coincides within 1 year of Camillo Golgi's centennial celebrations. It is quite remarkable that the structure and formation of this organelle is as controversial today as was its mere existence from Golgi's time to the 1950s, when EM approaches were introduced. Since the late 1950s, two opposing models of Golgi structure and function have split the Golgi scientific community, namely vesicular transport versus organelle maturation. Although a few years ago Golgi maturation seemed to be 'out for the count', it has recently seen an almost messianic revival. In this review, I argue that this large-scale desertion from the vesicle transport model to the maturation camp is premature. I propose an alternative, dynamic steady-state model, in which transient tubular connections function in parallel to vesicular transport and that the biosynthetic pathway is made up of three major distinct compartments: the ER, the Golgi and the TGN.
Topics: Animals; Cell Differentiation; Endoplasmic Reticulum; Golgi Apparatus; Humans; Membrane Proteins; Models, Biological; Protein Transport; Transport Vesicles; trans-Golgi Network
PubMed: 11208161
DOI: 10.1034/j.1600-0854.2000.010906.x -
Biochimica Et Biophysica Acta Aug 1998The creation and propagation of the intricate Golgi architecture during the cell cycle poses a fascinating problem for biologists. Similar to the inheritance process for... (Review)
Review
The creation and propagation of the intricate Golgi architecture during the cell cycle poses a fascinating problem for biologists. Similar to the inheritance process for nuclear DNA, the inheritance of the Golgi apparatus consists of biogenesis (replication) and partitioning (mitosis/meiosis) phases, in which Golgi components must double in unit mass, then be appropriately divided between nascent daughter cells during cytokinesis. In this article we focus discussion on the recent advances in the area of Golgi inheritance, first outlining our current understanding of the behaviour of the Golgi apparatus during cell division, then concluding with a more conceptual discussion of the Golgi biogenesis problem. Throughout, we attempt to integrate ultrastructural and biochemical findings with more recent information obtained using live cell microscopy and morphological techniques.
Topics: Animals; Cell Cycle; Cell Division; Golgi Apparatus; Humans; Mammals
PubMed: 9714778
DOI: 10.1016/s0167-4889(98)00051-2 -
Journal of Electron Microscopy Technique Feb 1991The Golgi apparatus response to pathological disorders is predominantly as an intermediary component of membrane biogenesis where it is involved in processing, sorting... (Review)
Review
The Golgi apparatus response to pathological disorders is predominantly as an intermediary component of membrane biogenesis where it is involved in processing, sorting and secretion of materials via secretory granules, and in the formation of lysosomes. A common initial response of the Golgi apparatus to any stress is an alteration or cessation of secretory activity. In the transformed cell, the Golgi apparatus is altered both morphologically and biochemically, suggesting a shift from a secretory to a membrane-generating mode of functioning. However, since fewer or less well-developed Golgi apparatus are frequently found in transformed cells, analytical methods of membrane isolation developed for normal tissues may not always yield equivalent results when applied to tumors. Cell surface alterations characteristic of malignant cells may result from modifications occurring at the level of the Golgi apparatus. Some lysosomal dysfunctions may result from underglycosylation of acid hydrolases by the Golgi apparatus. The use of cell-free systems between endoplasmic reticulum and Golgi apparatus or within Golgi apparatus cisterane is providing a new approach to the elucidation of the role of the Golgi apparatus in normal as well as pathological states.
Topics: Animals; Biological Transport; Cytoplasmic Granules; Golgi Apparatus; Humans; Lysosomes; Secretory Rate
PubMed: 2013821
DOI: 10.1002/jemt.1060170207 -
Cellular and Molecular Life Sciences :... Jan 2004The yeast Saccharomyces cerevisiae is one of the best-studied organisms to understand molecular mechanisms of membrane traffic, but as far as the organization of the... (Review)
Review
The yeast Saccharomyces cerevisiae is one of the best-studied organisms to understand molecular mechanisms of membrane traffic, but as far as the organization of the Golgi apparatus is concerned, yeast is only just beginning to yield clues about how dynamic and flexible the organelle is.
Topics: Endoplasmic Reticulum; Golgi Apparatus; Microscopy, Confocal; Protein Transport; Proteins; Saccharomyces cerevisiae
PubMed: 14745497
DOI: 10.1007/s00018-003-3356-5 -
The Plant Journal : For Cell and... Dec 2009Brefeldin A (BFA) is a useful tool for studying protein trafficking and identifying organelles in the plant secretory and endocytic pathways. At low concentrations (5-10...
Brefeldin A (BFA) is a useful tool for studying protein trafficking and identifying organelles in the plant secretory and endocytic pathways. At low concentrations (5-10 microg ml(-1)), BFA caused both the Golgi apparatus and trans-Golgi network (TGN), an early endosome (EE) equivalent in plant cells, to form visible aggregates in transgenic tobacco BY-2 cells. Here we show that these BFA-induced aggregates from the Golgi apparatus and TGN are morphologically and functionally distinct in plant cells. Confocal immunofluorescent and immunogold electron microscope (EM) studies demonstrated that BFA-induced Golgi- and TGN-derived aggregates are physically distinct from each other. In addition, the internalized endosomal marker FM4-64 co-localized with the TGN-derived aggregates but not with the Golgi aggregates. In the presence of the endocytosis inhibitor tyrphostin A23, which acts in a dose- and time-dependent manner, SCAMP1 (secretory carrier membrane protein 1) and FM4-64 are mostly excluded from the SYP61-positive BFA-induced TGN aggregates, indicating that homotypic fusion of the TGN rather than de novo endocytic trafficking is important for the formation of TGN/EE-derived BFA-induced aggregates. As the TGN also serves as an EE, continuously receiving materials from the plasma membrane, our data support the notion that the secretory Golgi organelle is distinct from the endocytic TGN/EE in terms of its response to BFA treatment in plant cells. Thus, the Golgi and TGN are probably functionally distinct organelles in plants.
Topics: Brefeldin A; Cells, Cultured; Endosomes; Golgi Apparatus; Molecular Sequence Data; Plant Proteins; Protein Transport; Pyridinium Compounds; Quaternary Ammonium Compounds; Nicotiana; Tyrphostins; trans-Golgi Network
PubMed: 19709389
DOI: 10.1111/j.1365-313X.2009.04007.x