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PubMed1998

The fragmented neuronal Golgi apparatus in amyotrophic lateral sclerosis includes the trans-Golgi-network: functional implications.

The Golgi apparatus (GA) of spinal cord motor neurons is fragmented in sporadic amyotrophic lateral sclerosis (ALS), and in asymptomatic and symptomatic transgenic mice expressing the G93A mutation of the gene of the human Cu,Zn superoxide dismutase, found in certain cases of familial ALS (FALS) [Gonatas NK (1994) Am J Pathol 145:751-761; Mourelatos Z, et al. (1996) Proc Natl Acad Sci USA 93:5472-5477]. A similar fragmentation of the GA has been described in cells treated with microtubule-depolymerizing drugs, where the organelle is functional and contains both Golgi stacks and trans-Golgi network (TGN), the compartment of exit and targeting of proteins processed by the GA. To gain a better definition of the structure of the fragmented neuronal GA in ALS, four cases of sporadic ALS with numerous Bunina bodies in spinal cord motor neurons were stained with antibodies against human TGN and against the lumenal and cytoplasmic domains of MG160, a protein of the medial cisternae of the GA. The fragmented GA was stained with the three antibodies, indicating the presence of both Golgi stacks and TGN. Furthermore, the staining of the fragmented GA by the antiserum against the cytoplasmic domain of MG160 indicates that the fragmentation of the GA is not the result of a terminal and global cytoplasmic lytic event. The Bunina bodies were not stained by the anti-MG160 antibodies, suggesting that they are not derived from the GA. The perikarya of neurons with fragmented GA showed normal immunoreactivity with antibodies against the heavy neurofilament subunit and alpha-tubulin. However, because of the lack of appropriate antibodies the localization of proteins such as spectrin, ankyrin, centractin and others which link the microtubules with the GA were not done. The findings support the hypothesis that, in ALS, the fragmented neuronal GA is functional. Additional work with animal models of ALS may establish whether the fragmentation of the GA is a sign of early degeneration or a compensatory reaction of the injured motor neuron.

Aged↗
PubMed1994

Inhibition by brefeldin A of NADH oxidation activity of rat liver Golgi apparatus accelerated by GDP.

Reduced pyridine nucleotide has been reported to enhance cell-free transfer of membrane material from a radiolabeled Golgi apparatus donor fraction from rat liver to an acceptor fraction consisting of inside-out plasma vesicles immobilized on nitrocellulose [(1992) Biochim. Biophys. Acta 1107, 131]. As part of a continuing effort to identify NADH-requiring enzymes in the Golgi apparatus which may be important to membrane trafficking, highly purified fractions of Golgi apparatus from rat liver were tested for their ability to oxidize NADH and the inhibition of the oxidation of NADH by brefeldin A. The isolated Golgi apparatus fractions were found to oxidize NADH with a specific activity comparable to that of the plasma membrane of rat liver. The activity was inhibited by brefeldin A and this inhibition was augmented by GDP. At near optimal concentrations of 7 microM brefeldin A and 1 microM GDP, the activity was > 90% inhibited. Brefeldin A inhibition of NADH oxidation by the Golgi apparatus was time-dependent and GDP appeared to accelerate the inhibition by brefeldin A.

Animals↗
PubMed1996

Rate of retrograde transport of cholera toxin from the plasma membrane to the Golgi apparatus and endoplasmic reticulum decreases during neuronal development.

Various glycolipid-binding toxins are internalized from the cell surface to the Golgi apparatus. Prominent among these is cholera toxin (CT), which consists of a pentameric B subunit that binds to ganglioside GM1 and an A subunit that mediates toxicity. We now demonstrate that rhodamine (Rh)-CT can be further internalized from the Golgi apparatus to the endoplasmic reticulum (ER) in cultured hippocampal neurons and in neuroblastoma N18TG-2 cells and that the A subunit is essential for retrograde transport to the ER. In addition, the rate of internalization of Rh-CT to the Golgi apparatus and ER decreases dramatically as hippocampal neurons mature. The Golgi apparatus was labeled in almost all 1-day-old neurons after < 1 h of incubation with Rh-CT but was labeled in < 10% of 14-day-old neurons after 1 h. During the first 14 days in culture, there was a 15-fold increase in the number of 125I-CT-binding sites per cell, indicating that the decrease in the rate of internalization of Rh-CT is not due to reduced levels of cell surface GM1 in older neurons. These results imply that the rate of retrograde transport of CT from the plasma membrane to the Golgi apparatus and ER is regulated during neuronal development and differentiation.

Animals↗
PubMed1999

Dynamic association of cytoplasmic dynein heavy chain 1a with the Golgi apparatus and intermediate compartment.

Microtubule motors, such as the minus end-directed motor, cytoplasmic dynein, play an important role in maintaining the integrity, intracellular location, and function of the Golgi apparatus, as well as in the translocation of membrane between the endoplasmic reticulum and Golgi apparatus. We have immunolocalised conventional cytoplasmic dynein heavy chain to the Golgi apparatus in cultured vertebrate cells. In addition, we present evidence that cytoplasmic dynein heavy chain cycles constitutively between the endoplasmic reticulum and Golgi apparatus: it colocalises partially with the intermediate compartment, it is found on nocodazole-induced peripheral Golgi elements and, most strikingly, on Brefeldin A-induced tubules that are moving towards microtubule plus ends. The direction of movement of membrane between the endoplasmic reticulum and Golgi apparatus is therefore unlikely to be regulated by controlling motor-membrane interactions: rather, the motors probably remain bound throughout the whole cycle, with their activity being modulated instead. We also report that the overexpression of p50/dynamitin results in the loss of cytoplasmic dynein heavy chain from the membrane of peripheral Golgi elements. These results explain how dynamitin overexpression causes the inhibition of endoplasmic reticulum-to-Golgi transport complex movement towards the centrosomal region, and support the general model that an intact dynactin complex is required for cytoplasmic dynein binding to all cargoes.

Amino Acid Sequence↗
PubMed1981

A quantitative study of the position of the Golgi apparatus in the early developing chick eye.

A quantitative evaluation of the positional changes of the Golgi apparatus during the invagination of the lens placode and the presumptive neural retina of the chick embryo was carried out by silver impregnation. The Golgi apparatus is predominantly polarized in the apical process of the elongated interphasic cells; however, basal and lateral positions are also present. When the nuclei are located close to the luminal surface, basal and lateral positions increase significantly showing that a loss of Golgi apparatus polarization takes place, associated with the mitotic cycle. At the beginning of the invagination of lens and neural retina rudiments, a marked shift in orientation occurs between lateral and apical positions of the Golgi apparatus; this is associated with the nuclei located close to the luminal surface. The possible significance of these results is related to some processes concerning the invagination of these rudiments, such as interkinetic nuclear migration and secretion of extracellular materials.

Animals↗
PubMed1997

Partitioning of the Golgi apparatus during mitosis in living HeLa cells.

The Golgi apparatus of HeLa cells was fluorescently tagged with a green fluorescent protein (GFP), localized by attachment to the NH2-terminal retention signal of N-acetylglucosaminyltransferase I (NAGT I). The location was confirmed by immunogold and immunofluorescence microscopy using a variety of Golgi markers. The behavior of the fluorescent Golgi marker was observed in fixed and living mitotic cells using confocal microscopy. By metaphase, cells contained a constant number of Golgi fragments dispersed throughout the cytoplasm. Conventional and cryoimmunoelectron microscopy showed that the NAGT I-GFP chimera (NAGFP)-positive fragments were tubulo-vesicular mitotic Golgi clusters. Mitotic conversion of Golgi stacks into mitotic clusters had surprisingly little effect on the polarity of Golgi membrane markers at the level of fluorescence microscopy. In living cells, there was little self-directed movement of the clusters in the period from metaphase to early telophase. In late telophase, the Golgi ribbon began to be reformed by a dynamic process of congregation and tubulation of the newly inherited Golgi fragments. The accuracy of partitioning the NAGFP-tagged Golgi was found to exceed that expected for a stochastic partitioning process. The results provide direct evidence for mitotic clusters as the unit of partitioning and suggest that precise regulation of the number, position, and compartmentation of mitotic membranes is a critical feature for the ordered inheritance of the Golgi apparatus.

Cells, Cultured↗
PubMed1995

Redistribution of microtubules and Golgi apparatus in herpes simplex virus-infected cells and their role in viral exocytosis.

Earlier studies have shown that the Golgi apparatus was fragmented and dispersed in herpes simplex virus 1-infected Vero and HEp-2 cells but not in human 143TK- cells, that the fragmentation and dispersal required viral functions expressed concurrently with or after the onset of DNA synthesis (G. Campadelli-Fiume, R. Brandimarti, C. Di Lazzaro, P. L. Ward, B. Roizman, and M. R. Torrisi, Proc. Natl. Acad. Sci. USA 90:2798-2802, 1993), and that in 143TK- cells, but not Vero or HEp-2 cells, infected with viral mutants lacking the UL20 gene virions were glycosylated and transported to extracellular space (J. D. Baines, P. L. Ward, G. Campadelli-Fiume, and B. Roizman, J. Virol. 65:6414-6424, 1991; E. Avitabile, P. L. Ward, C. Di Lazzaro, M. R. Torrisi, B. Roizman, and G. Campadelli-Fiume, J. Virol. 68:7397-7405, 1994). Experiments designed to elucidate the role of the microtubules and of intact or fragmented Golgi apparatus in the exocytosis of virions showed the following. (i) In all cell lines tested (Vero, 143TK-, BHK, and Hep-2) microtubules underwent fragmentation particularly evident at the cell periphery and then reorganized into bundles which circumvent the nucleus. This event was not affected by inhibitors of viral DNA synthesis. We conclude that redistribution of microtubules may be required but is not sufficient for the fragmentation and dispersal of the Golgi apparatus. (ii) In all infected cell lines tested, nocodazole caused fragmentation and dispersal of the Golgi and a far more extensive depolymerization of the microtubules than was seen in untreated, infected Vero or HEp-2 cells. Taxol precluded the depolymerization of the microtubules and fragmentation of the Golgi in both infected cell lines. Neither nocodazole nor taxol affected the exocytosis of infectious virus from Vero, HEp-2, or 143TK- cells infected with wild-type virus. We conclude that the effects of nocodazole or of taxol are dominant over the effects of viral infection in the cell lines tested and that viral exocytosis is independent of the organization of microtubules or of the integrity of the Golgi apparatus. Lastly, the data suggest that herpes simplex viruses have evolved an exocytic pathway for which the UL20 protein is a component required in some cells but not others and in which this protein does not merely compensate for the fragmentation and dispersal of the Golgi apparatus.

Animals↗
PubMed1998

Direct pathway from early/recycling endosomes to the Golgi apparatus revealed through the study of shiga toxin B-fragment transport.

Shiga toxin and other toxins of this family can escape the endocytic pathway and reach the Golgi apparatus. To synchronize endosome to Golgi transport, Shiga toxin B-fragment was internalized into HeLa cells at low temperatures. Under these conditions, the protein partitioned away from markers destined for the late endocytic pathway and colocalized extensively with cointernalized transferrin. Upon subsequent incubation at 37 degreesC, ultrastructural studies on cryosections failed to detect B-fragment-specific label in multivesicular or multilamellar late endosomes, suggesting that the protein bypassed the late endocytic pathway on its way to the Golgi apparatus. This hypothesis was further supported by the rapid kinetics of B-fragment transport, as determined by quantitative confocal microscopy on living cells and by B-fragment sulfation analysis, and by the observation that actin- depolymerizing and pH-neutralizing drugs that modulate vesicular transport in the late endocytic pathway had no effect on B-fragment accumulation in the Golgi apparatus. B-fragment sorting at the level of early/recycling endosomes seemed to involve vesicular coats, since brefeldin A treatment led to B-fragment accumulation in transferrin receptor-containing membrane tubules, and since B-fragment colocalized with adaptor protein type 1 clathrin coat components on early/recycling endosomes. Thus, we hypothesize that Shiga toxin B-fragment is transported directly from early/recycling endosomes to the Golgi apparatus. This pathway may also be used by cellular proteins, as deduced from our finding that TGN38 colocalized with the B-fragment on its transport from the plasma membrane to the TGN.

Adaptor Protein Complex gamma Subunits↗
PubMed1977

Histochemical studies on the morphology of the Golgi apparatus and on the distribution of some enzymes concerned with carbodydrate metabolism in the rat cerebellum.

Detailed histochemical studies have been conducted on the distribution of various enzymes, including thiamine pyrophosphatase, alpha-glucan phosphorylase, hexokinase, glucose-6-phosphate dehydrogenase, aldolase, glycerol-3-phosphate dehydrogenase; menadion oxidoreductase, lactate dehydrogenase and succinate dehydrogenase in various components of the cerebellum of healthy adult male rats of the Wistar strain. The thiamine pyrophosphatase reaction showed the morphological patterns of the GOLGI apparatus characteristic for each kind of cells. The GOLGI apparatus is a simple network in stellate cells, but it can be classified into the same 5 categories in basket cells and GOLGI type II cells. The GOLGI apparatus in the latter 2 cell types appears to undergo cyclic changes. A few GOLGI type II cells have a supranuclear form (Type II) and some cells show disintegration and "budding-off" of the GOLGI apparatus. The GOLGI apparatus in PURKINJE cells can be classified into 4 categories including a perinuclear strand form (Type III), but most of them show randomly distributed granules and vesicles. Lightly stained networks are observable in astrocytes and oligodendrocytes. They do not show polarity in astrocytes whereas they have extensions in a few oligodendrocytes. BERGMANN glia may undergo cyclic changes indicating more advance differentiation than astrocytes and oligodendrocytes. Cerebellar glomerula show lightly stained networks with many fine granules. Granule cells, stellate cells, and basket cells are all poorly equipped equally with the EMBDEN-MEYERHOF (EM) pathway and with the hexosemonophosphate (HMP) shunt. GOLGI type II cells are richly equipped almost equally with both the EM pathway and the HMP shunt. All these neurons probably derive energy mainly from glucose in the circulating blood. PURKINJE cells may belong to the category of "usual neurons", because they are moderately equipped both with the EM pathway and the HMP shunt. However, they may derive their energy from the BERGMANN glia which have intense hexokinase activity but weak succinate dehydrogenase activity. The BERGMANN glia are more richly equipped with the HMP shunt than with the EM pathway and are rich in lactate dehydrogenase suggesting an "exceptional metabolic pattern". These glia may have active synthesizing ability. Astrocytes and oligodendrocytes are equipped with all the enzymes tested, and they show a tendency to surround the glomeruli. It is suggested that the glomerula may be surrounded by the glial sheaths with strong hexokinase activity, and that they may contain alpha-glucan phosphorylase, glucose-6-phosphate dehydrogenase, and glycerol-3-phosphate dehydrogenase in addition to the succinate dehydrogenase already reported. A few PURKINJE cells showed perinuclear concentrations of the reaction product only of succinate dehydrogenase at the sites of contacts between nucleoli and nuclear membranes. It is suggested that the nucleolus may receive adenosine at the sites of contacts between nucleoli and nuclear membranes...

Animals↗
PubMed2004

The AE2 anion exchanger is necessary for the structural integrity of the Golgi apparatus in mammalian cells.

The structural integrity of the Golgi apparatus is known to be dependent on multiple factors, including the organizational status of microtubules, actin and the ankyrin/spectrin-based Golgi membrane skeleton, as well as vesicular trafficking and pH homeostasis. In this respect, our recently identified Golgi-associated anion exchanger, AE2, may also be of importance, since it potentially acts as a Golgi pH regulator and as a novel membrane anchor for the spectrin-based Golgi membrane skeleton. Here, we show that inhibition (>75%) of AE2 expression by antisense oligonucleotides in COS-7 cells results in the fragmentation of the juxtanuclear Golgi apparatus and in structural disorganization of the Golgi stacks, the cisternae becoming generally shorter, distorted, vesiculated and/or swollen. These structural changes occurred without apparent dissociation of the Golgi membrane skeletal protein Ankyrin(195), but were accompanied by the disappearance of the well-focused microtubule-organizing center (MTOC), suggesting the involvement of microtubule reorganization. Similar changes in Golgi structure and assembly of the MTOC were also observed upon transient overexpression of the EGFP-AE2 fusion protein. These data implicate a clear structural role for the AE2 protein in the Golgi and in its cytological positioning around the MTOC.

Animals↗
PubMed1973

The effect of a lipid-rich diet on the properties and composition of lipoprotein particles from the Golgi apparatus of guinea-pig liver.

1. A cell fraction rich in Golgi apparatus was isolated from the livers of guinea pigs fed on a lipid-rich diet (1.6% cholesterol, 15% corn oil). 2. The Golgi cisternae and secretory vesicles contained electron-dense particles which were tentatively identified as VLD (very-low-density) and LD (low-density) lipoproteins. Particles of moderate electron density, 150-500nm in diameter, were seen associated with membranous elements of the Golgi-apparatus cell fraction. Disruption of this cell fraction permitted the release of these three species of particles, which were separated into particulate lipid, and VLD and LD lipoproteins. 3. The large particles of moderate electron density, isolated as particulate lipid, were distinct from both species of Golgi particles in their chemical composition and in possessing an immunochemically unreactive apolipoprotein(s). Morphological observations suggest that the particulate lipid arose from cytoplasmic lipid droplets which were present as contaminants of the Golgi-rich fraction. 4. The chemical and immunochemical results are consistent with the suggestion that the Golgi LD particles are precursors of the VLD particles, into which they may be transformed by the addition of both triglyceride and cholesteryl ester. The present results provide further support for the proposal that the Golgi VLD particles are precursors of the serum VLD lipoproteins in the guinea pig. 5. Hepatic Golgi VLD particles isolated from guinea pigs fed on the lipid-rich diet contained significantly higher molar amounts (relative to protein) of both cholesteryl ester and triglyceride than similar particles from animals fed on a normal diet. These results suggest that the type of Golgi VLD particle produced from the LD particle is a direct consequence of the amount and composition of the dietary lipid. 6. Hepatic Golgi LD particles isolated from guinea pigs fed on different diets were similar in chemical composition and contained approx. 50% by weight of phospholipid. We conclude that the Golgi LD particle is normally present in the Golgi-apparatus cell fraction from guinea-pig liver, and may represent the end product of lipoprotein biosynthesis in the smooth endoplasmic reticulum. 7. The serum LD lipoproteins and Golgi LD particles were quite distinct in chemical composition. However, these two lipoprotein species were immunochemically identical and exhibited a similar range of flotation rate. It appears unlikely that the Golgi LD particles are secreted as the precursors of the serum LD lipoproteins.

Animals↗
PubMed1991

Localization of glycosylation sites in the Golgi apparatus using immunolabeling and cytochemistry.

This review summarizes data on the distribution of certain glycosylation steps in the Golgi apparatus as revealed by immunolabeling and lectin techniques. The methodical basis for such investigations was provided by the introduction of the colloidal gold marker system for immunolabeling and the development of new means of tissue processing such as the low-temperature embedding technique using Lowicryl K4M. The application of these techniques together with highly specific antibodies has provided much of the basis for our current understanding of the Golgi apparatus in functional terms. Thus, in many cell types, three Golgi apparatus compartments can be distinguished, whereas in others no such functional subdivision is evident. Investigations on sialyltransferase distribution have also provided direct evidence that GERL is structurally and functionally part of the Golgi apparatus.

Animals↗
PubMed1991

Behavior of a transitional tubulovesicular compartment at the cis side of the Golgi apparatus in in vivo fusion studies of mammalian cells.

We have investigated the behavior in in vivo cell fusion experiments of a transitional compartment lying between the endoplasmic reticulum and Golgi apparatus to determine if the compartment, as recognized by the antibody G1/93, might congregate in a similar manner to Golgi apparatus [W. C. Ho et al. (1990) Eur. J. Cell Biol. 52, 315-327]. The distributions of the transitional tubulovesicular compartment, endoplasmic reticulum, and Golgi apparatus in HeLa cells were assessed by immunofluorescent staining using mouse monoclonal antibody G1/93, mouse monoclonal antibody HP 24, and rabbit anti-galactosyltransferase, respectively. In agreement with previous results [W. C. Ho et al. (1990) Eur. J. Cell Biol. 52, 315-327], the Golgi apparatus was observed to congregate gradually over a 3- to 6-h period, forming a large, extended, central Golgi complex in uv-inactivated Sindbis virus-fused HeLa cells. Concomitant with this was a marked congregation of the transitional tubulovesicular compartment. Congregation of the tubulovesicular compartment was not affected by cycloheximide. The endoplasmic reticulum retained its web-like distribution throughout the syncytoplasm and rimmed the nuclear periphery. Treatment of HeLa cells with nocodazole prior to fusion followed by incubation of the syncytia in drug-containing media blocked congregation of the G1/93-positive compartment. With this long-term nocodazole treatment, Golgi apparatus was dispersed into scattered Golgi elements and the G1/93 distribution was endoplasmic reticulum-like. These results suggest that the transitional tubulovesicular compartment recognized by G1/93 is normally structured on microtubules and microtubule organizing centers and may be considered to be a subcompartment of a greater, perinuclear, Golgi complex.

Antibodies, Monoclonal↗
PubMed1981

Ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) in the Golgi apparatus of early spermatids of the rat.

At the early steps 3-7 of spermiogenesis the hemispherical Golgi apparatus elaborates and is closely associated to the acrosomic system which grows at the surface of the spermatid's nucleus. It shows two distinct zones, a cortex made up of flattened saccules and related membranous tubules, and a medulla containing various types of vesicular profiles. The various components of the cortex of the Golgi apparatus were tested for their reactivity to three phosphatases. Nicotinamide adenine dinucleotide phosphatase activity (NADPase, Smith, 1980) was observed in the middle two to six saccules in the stack with a midsaccule being more reactive than the saccules above and below. A weak and spotty reaction was also noted in the remaining saccules on the trans-face of the stack and in the thick elements making up the GERL on the trans aspect of the stacks of saccules. Thiamine pyrophosphatase activity (TPPase, Novikoff and Goldfisher, 1961) was found in one or two saccules on the trans-face of the stacks but was absent from the other Golgi components. Cytidine monophosphatase activity (CMPase, Novikoff, 1967) was observed in the GERL, in vesicles of the medulla and in the developing acrosomic system. In the intersaccular regions of the cortex the branching membranous tubules showed the same reactivity for the phosphatases to that of the saccules to which they are connected. ER cisternae associated with the Golgi apparatus, anastomotic membranous tubules seen in the peripheral Golgi region, small vesicles, as well as the first saccule on the cis-face of the stacks were all negative for the three enzymes studied. These data indicated that in the cortex of the Golgi apparatus there were several distinct compartments that could be distinguished on the basis of structural and cytochemical features.

Animals↗
PubMed2002

Inactivation of Galpha(z) causes disassembly of the Golgi apparatus.

We showed previously that overexpression of the alpha subunit of G(z) or G(i2) suppresses nordihydroguaiaretic acid-induced Golgi disassembly. To determine whether the active form of Galpha is required to maintain the structure of the Golgi apparatus, we examined the effects of a series of Galpha GAPs, regulators of G protein signaling (RGS) proteins, on the Golgi structure. Expression of RGSZ1 or RGSZ2, both of which exhibit high selectivity for Galpha(z), markedly induced dispersal of the Golgi apparatus, whereas expression of RGS proteins that are rather selective for Galpha(q) or other Galpha(i) species did not. A mutated RGSZ1, which is deficient in the interaction with Galpha(z), did not induce Golgi disassembly. These results suggest that the active form of Galpha(z), but not Galpha(i2), is crucial for maintenance of the structure of the Golgi apparatus. Consistent with this idea, Golgi disruption also took place in cells transfected with a dominant-negative Galpha(z) mutant. Although previous studies showed that the expression of Galpha(z) is confined to neuronal cells and platelets, immunofluorescence and mRNA expression analyses revealed that it is also expressed, albeit at low levels, in non-neuronal cells, and is located in the Golgi apparatus. These results taken together suggest a general regulatory role for Galpha(z) in the control of the Golgi structure.

Animals↗
PubMed1999

Low cytoplasmic pH causes fragmentation and dispersal of the Golgi apparatus in human hepatoma cells.

The centrosomal localization of the Golgi apparatus in interphase cells is thought to be maintained by retrograde microtubule-based motility. It is well established that, when intracellular pH is lowered, lysosomes and endosomes, also showing pericentrosomal localization, translocate towards the plus ends of microtubules within 15 min. In this study, we found that prolonged incubation in low pH medium (pH 6.6) with 20 mM Na acetate induced the fragmentation and dispersal of the Golgi apparatus in the human hepatoma cell line PLC/PRF/5. The fraction of Golgi-dispersed cells increased in a time-dependent manner, and reached over 60% after the 16-h incubation. The cytoplasmic pH was dropped to approximately 7.10. Replacement with normal pH medium restored the structure and localization of the apparatus within 30 min. In the low pH condition, the microtubular network and endoplasmic reticulum appeared normal, and cytoplasmic dynein was still bound to the fragmented Golgi membranes. These findings suggest that low cytoplasmic pH suppresses the retrograde movement of the Golgi apparatus as well as that of lysosomes and endosomes.

Carcinoma, Hepatocellular↗
PubMed1996

Golgi apparatus and intraneuronal inclusions of anterior horn cells in amyotrophic lateral sclerosis: an immunohistochemical study.

We applied immunohistochemical techniques to study alterations of the Golgi apparatus, and to determine possible relationships between this complex and the intraneuronal inclusions of lower motor neurons of patients with the sporadic form of amyotrophic lateral sclerosis (ALS). Spinal cords from normal individuals served as controls. Monoclonal antibodies to the Golgi zone and to Golgi beta-COP protein were used. Immunoreactivity with these antibodies was seen in frozen sections of paraformaldehyde-fixed spinal cord tissue, but not in formalin-fixed, paraffin-embedded specimens. The immunoreaction products were seen as granular structures, diffusely distributed in neurons and glial cells. Although immunostaining of some ALS neurons was reduced, fragmentation of the Golgi apparatus was not evident with either antibody. Bunina bodies and skein-like inclusions, characteristically found in spinal anterior horn cells of ALS patients, were not stained by these antibodies to epitopes of the Golgi apparatus, nor were Lewy body-like hyaline inclusions, present in some cases of sporadic ALS and reported to be characteristic to familial ALS with posterior column degeneration. These results suggest that components of the Golgi apparatus are not directly incorporated into intraneuronal inclusions. However, the possibility that abnormal proteinaceous material of the Golgi apparatus may be involved in their genesis cannot be ruled out.

Adult↗
PubMed1990

Transfer of secretory proteins from the endoplasmic reticulum to the Golgi apparatus: discrimination between homologous and heterologous transfer in intact heterokaryons.

To examine aspects of the transfer of secretory proteins from the endoplasmic reticulum to the Golgi apparatus in situ, heterokaryons were formed between Hep G2 human hepatoma cells and WI-38 human fibroblasts. The cells were appropriately treated with cycloheximide before fusion, which emptied them of their respective secretory proteins, serum albumin for the Hep G2 cells and procollagen I for the WI-38 cells. After fusion was complete, the cycloheximide was washed out, protein synthesis was resumed, and the rates of reappearance of serum albumin and procollagen I in the two separated Golgi apparatuses within each heterokaryon were followed by immunofluorescence microscopy. Serum albumin was found to always reappear first in the Golgi apparatus contributed by the Hep G2 half of the heterokaryon, and procollagen I in the Golgi apparatus of the WI-38 half. These results suggest that the endoplasmic reticulum-to-Golgi apparatus transfer in situ is not simply a stochastic process but is either spatially restricted or exhibits cell-type specificity or both.

Carcinoma, Hepatocellular↗