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FEBS Letters Jun 2001The N-glycans found on eukaryotic glycoproteins occur in a vast range of different structures. A universal N-glycan core is attached to proteins during synthesis in the... (Review)
Review
The N-glycans found on eukaryotic glycoproteins occur in a vast range of different structures. A universal N-glycan core is attached to proteins during synthesis in the endoplasmic reticulum, and then diversity is generated as the proteins pass through the Golgi apparatus. Many of the Golgi-localised glycosyltransferases have now been identified in both yeast and mammalian cells, but it is still unclear how these enzymes are integrated into the Golgi and the rest of the cell so as to ensure efficient and specific processing of passing substrates. This review discusses the potential of the yeast system to address these issues.
Topics: Glycosylation; Glycosyltransferases; Golgi Apparatus; Humans; Mannans; Molecular Structure; Polysaccharides; Saccharomyces cerevisiae; Substrate Specificity
PubMed: 11412862
DOI: 10.1016/s0014-5793(01)02488-7 -
Histochemistry and Cell Biology Feb 2014Various proteins are involved in the generation and maintenance of the membrane complex known as the Golgi apparatus. We have used mutant Chinese hamster ovary (CHO)...
Various proteins are involved in the generation and maintenance of the membrane complex known as the Golgi apparatus. We have used mutant Chinese hamster ovary (CHO) cell lines Lec4 and Lec4A lacking N-acetylglucosaminyltransferase V (GlcNAcT-V, MGAT5) activity and protein in the Golgi apparatus to study the effects of the absence of a single glycosyltransferase on the Golgi apparatus dimension. Quantification of immunofluorescence in serial confocal sections for Golgi α-mannosidase II and electron microscopic morphometry revealed a reduction in Golgi volume density up to 49 % in CHO Lec4 and CHO Lec4A cells compared to parental CHO cells. This reduction in Golgi volume density could be reversed by stable transfection of Lec4 cells with a cDNA encoding Mgat5. Inhibition of the synthesis of β1,6-branched N-glycans by swainsonine had no effect on Golgi volume density. In addition, no effect on Golgi volume density was observed in CHO Lec1 cells that contain enzymatically active GlcNAcT-V, but cannot synthesize β1,6-branched glycans due to an inactive GlcNAcT-I in their Golgi apparatus. These results indicate that it may be the absence of the GlcNAcT-V protein that is the determining factor in reducing Golgi volume density. No dimensional differences existed in cross-sectioned cisternal stacks between Lec4 and control CHO cells, but significantly reduced Golgi stack hits were observed in cross-sectioned Lec4 cells. Therefore, the Golgi apparatus dimensional change in Lec4 and Lec4A cells may be due to a compaction of the organelle.
Topics: Animals; CHO Cells; Cricetinae; Cricetulus; Golgi Apparatus; Microscopy, Confocal; Mutation; N-Acetylglucosaminyltransferases
PubMed: 24078077
DOI: 10.1007/s00418-013-1146-1 -
Current Biology : CB Apr 2018Muschalik and Munro introduce golgins and their roles as vesicle tethers and scaffolds at the Golgi. (Review)
Review
Muschalik and Munro introduce golgins and their roles as vesicle tethers and scaffolds at the Golgi.
Topics: Animals; Autoantigens; Biological Evolution; Evolution, Molecular; Golgi Apparatus; Golgi Matrix Proteins; Humans; Mammals; Membrane Proteins
PubMed: 29689216
DOI: 10.1016/j.cub.2018.01.006 -
Autophagy Jul 2024The development of alcohol-associated liver disease (ALD) is associated with disorganized Golgi apparatus and accelerated phagophore formation. While Golgi membranes may...
The development of alcohol-associated liver disease (ALD) is associated with disorganized Golgi apparatus and accelerated phagophore formation. While Golgi membranes may contribute to phagophores, association between Golgi alterations and macroautophagy/autophagy remains unclear. GOLGA4/p230 (golgin A4), a dimeric Golgi matrix protein, participates in phagophore formation, but the underlying mechanism is elusive. Our prior research identified ethanol (EtOH)-induced Golgi scattering, disrupting intra-Golgi trafficking and depleting RAB3D GTPase from the -Golgi. Employing various techniques, we analyzed diverse cellular and animal models representing chronic and chronic/binge alcohol consumption. In -Golgi of non-treated hepatocytes, we found a triple complex formed between RAB3D, GOLGA4, and MYH10/NMIIB (myosin, heavy polypeptide 10, non-muscle). However, EtOH-induced RAB3D downregulation led to MYH10 segregation from the Golgi, accompanied by Golgi fragmentation and tethering of the MYH10 isoform, MYH9/NMIIA, to dispersed Golgi membranes. EtOH-activated autophagic flux is evident through increased WIPI2 recruitment to the Golgi, phagophore formation, enhanced LC3B lipidation, and reduced SQSTM1/p62. Although GOLGA4 dimerization and intra-Golgi localization are unaffected, loss of RAB3D leads to an extension of the cytoplasmic N terminal domain of GOLGA4, forming GOLGA4-positive phagophores. Autophagy inhibition by hydroxychloroquine (HCQ) prevents alcohol-mediated Golgi disorganization, restores distribution of ASGR (asialoglycoprotein receptor), and mitigates COL (collagen) deposition and steatosis. In contrast to short-term exposure to HCQ, extended co-treatment with both EtOH and HCQ results in the depletion of LC3B protein via proteasomal degradation. Thus, (a) RAB3D deficiency and GOLGA4 conformational changes are pivotal in MYH9-driven, EtOH-mediated Golgiphagy, and (b) HCQ treatment holds promise as a therapeutic approach for alcohol-induced liver injury.: ACTB: actin, beta; ALD: alcohol-associated liver disease; ASGR: asialoglycoprotein receptor; AV: autophagic vacuoles; EM: electron microscopy; ER: endoplasmic reticulum; EtOH: ethanol; HCQ: hydroxychloroquine; IP: immunoprecipitation; KD: knockdown; KO: knockout; MYH10/NMIIB: myosin, heavy polypeptide 10, non-muscle; MYH9/NMIIA: myosin, heavy polypeptide 9, non-muscle; PLA: proximity ligation assay; ORO: Oil Red O staining; PM: plasma membrane; TGN: -Golgi network; SIM: structured illumination super-resolution microscopy.
Topics: Golgi Apparatus; Humans; Animals; Down-Regulation; Autophagy; Ethanol; rab3 GTP-Binding Proteins; Mice; Hepatocytes; Mice, Inbred C57BL
PubMed: 38591519
DOI: 10.1080/15548627.2024.2329476 -
Current Opinion in Cell Biology Aug 2017The Golgi apparatus is tightly integrated into the cellular system where it plays essential roles required for a variety of cellular processes. Its vital functions... (Review)
Review
The Golgi apparatus is tightly integrated into the cellular system where it plays essential roles required for a variety of cellular processes. Its vital functions include not only processing and sorting of proteins and lipids, but also serving as a signaling hub and a microtubule-organizing center. Golgi stacks in mammalian cells are interconnected into a compact ribbon in the perinuclear region. However, the ribbon can undergo distinct disassembly processes that reflect the cellular state or environmental demands and stress. For instance, its most dramatic change takes place in mitosis when the ribbon is efficiently disassembled into vesicles through a combination of ribbon unlinking, cisternal unstacking and vesiculation. Furthermore, the ribbon can also be detached and positioned at specific cellular locations to gain additional functionalities during differentiation, or fragmented to different degrees along disease progression or upon cell death. Here, we describe the major morphological alterations of Golgi ribbon disassembly under physiological and pathological conditions and discuss the underlying mechanisms that drive these changes.
Topics: Animals; Cell Differentiation; Disease Progression; Golgi Apparatus; Humans; Microtubules; Mitosis; Organ Specificity; Protein Transport; Signal Transduction
PubMed: 28390244
DOI: 10.1016/j.ceb.2017.03.008 -
Cell and Tissue Research Jun 2011The eukaryotic Golgi apparatus is characterized by a stack of flattened cisternae that are surrounded by transport vesicles. The organization and function of the Golgi... (Review)
Review
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.
Topics: Animals; Golgi Apparatus; Humans
PubMed: 21494806
DOI: 10.1007/s00441-011-1166-x -
FEBS Letters Jun 1996The mitotic disassembly and reassembly of the mammalian Golgi apparatus is an ideal system to study the molecular mechanisms involved in biogenesis and maintenance of... (Review)
Review
The mitotic disassembly and reassembly of the mammalian Golgi apparatus is an ideal system to study the molecular mechanisms involved in biogenesis and maintenance of membranous organelles. As cells enter M-phase, Golgi stacks are converted into Golgi clusters of small membrane fragments, which are dispersed throughout the cytoplasmic space during metaphase. Disassembly is dependent on the action of cdc2-kinase and at least two distinct pathways contribute to the fragmentation: one involves the budding of COP I-coated vesicles from Golgi cisternae, the other is a less well characterised COP I-independent pathway. During telophase, the Golgi fragments reassemble and fuse into a fully functional Golgi stack, using at least two distinct ATPase-mediated fusion pathways.
Topics: Animals; Golgi Apparatus; Mammals; Mitosis
PubMed: 8682208
DOI: 10.1016/0014-5793(96)00518-2 -
Traffic (Copenhagen, Denmark) Mar 2008The secretory route in eukaryotic cells has been regarded as one common pathway from the endoplasmic reticulum (ER) through the Golgi cisternae to the trans Golgi... (Review)
Review
The secretory route in eukaryotic cells has been regarded as one common pathway from the endoplasmic reticulum (ER) through the Golgi cisternae to the trans Golgi network where recognition, sorting and exit of cargo molecules are thought to occur. Morphologically, the ribosome-coated ER is observed throughout the cytoplasm, while the Golgi apparatus usually is confined to a perinuclear position in mammalian cells. However, Golgi outposts have been observed in neuronal dendrites and dispersed Golgi elements in skeletal muscle myofibers. In insects, like in Drosophila melanogaster imaginal disc cells and epidermal cells of Tobacco and Arabidopsis leafs, individual Golgi stacks are distributed throughout the cytoplasm. Golgi stacks do not only differ in their intracellular localization but also in the number of stacks from one to several hundreds. Each stack consists of closely aligned, flattened, membrane-limited cisternae. The number of cisternae in a Golgi stack is also variable, 2-3 in some ciliates, 10 in many plant cell types and up to 30 in certain euglenoids. The yeast Saccharomyces cerevisiae has a Golgi structure of minimal complexity with scattered solitary cisternae. It is assumed that the number of Golgi cisternae reflects the overall complexity of the enzymatic reactions that occur in their lumen, while the number of stacks reflects the load of macromolecules arriving at the cis side. In this review, we will focus on how the available morphological and biochemical data fit with the current view of protein sorting in the secretory pathway, particularly in polarized cells like neuronal and epithelial cells.
Topics: Animals; Cell Polarity; Endoplasmic Reticulum; Epithelial Cells; Golgi Apparatus; Models, Biological; Protein Transport; trans-Golgi Network
PubMed: 18088319
DOI: 10.1111/j.1600-0854.2007.00690.x -
The Journal of Cell Biology Dec 2001In this issue, Short et al. report the discovery of a protein named Golgin-45 that is located on the surface of the middle (or medial) cisternae of the Golgi complex.... (Review)
Review
In this issue, Short et al. report the discovery of a protein named Golgin-45 that is located on the surface of the middle (or medial) cisternae of the Golgi complex. Depletion of this protein disrupts the Golgi complex and leads to the return of a resident, lumenal, medial Golgi enzyme to the endoplasmic reticulum. These findings suggest that Golgin-45 serves as a linchpin for the maintenance of Golgi complex structure, and offer hints as to the mechanisms by which the polarized Golgi complex is constructed.
Topics: Animals; Golgi Apparatus; Humans; Membrane Proteins; Protein Transport
PubMed: 11739400
DOI: 10.1083/jcb.200109095 -
Trends in Cell Biology Jan 1998The thin membrane of the endoplasmic reticulum matures into the thick plasma membrane in the Golgi apparatus. Along the way, the concentrations of cholesterol and... (Review)
Review
The thin membrane of the endoplasmic reticulum matures into the thick plasma membrane in the Golgi apparatus. Along the way, the concentrations of cholesterol and sphingolipids increase. Here, Gerrit van Meer discusses how this phenomenon may reflect an intricate lipid-protein sorting machinery. Synthesis of sphingolipids, translocation across the Golgi membrane and lateral segregation into lumenal domains seem to be key events. In addition, signalling lipids indicate the lipid status of the Golgi and interact with proteins of the transport machinery to regulate membrane flux.
Topics: Animals; Biological Transport; Golgi Apparatus; Humans; Intracellular Membranes; Membrane Lipids; Models, Biological; Signal Transduction
PubMed: 9695805
DOI: 10.1016/s0962-8924(97)01196-3