scholarly journals Stacks off tracks: A role for the golgin AtCASP in plant endoplasmic reticulum – Golgi apparatus tethering

2017 ◽  
Author(s):  
Anne Osterrieder ◽  
Stan W Botchway ◽  
Andy Ward ◽  
Tijs Ketelaar ◽  
Norbert de Ruijter ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Matrix Material ◽  
Coiled Coil ◽  
Golgi Body ◽  
In Planta ◽  
Golgi Bodies ◽  
Dual Colour

AbstractThe plant Golgi apparatus modifies and sorts incoming proteins from the endoplasmic reticulum (ER), and synthesises cell wall matrix material. Plant cells possess numerous motile Golgi bodies, which are connected to the ER by yet to be identified tethering factors. Previous studies indicated a role of cis-Golgi plant golgins (long coiled-coil domains proteins anchored to Golgi membranes) in Golgi biogenesis. Here we show a tethering role for the golgin AtCASP at the ER-Golgi interface. Using live-cell imaging, Golgi body dynamics were compared in Arabidopsis thaliana leaf epidermal cells expressing fluorescently tagged AtCASP, a truncated AtCASP-ΔCC lacking the coiled-coil domains, and the Golgi marker STtmd. Golgi body speed and displacement were significantly reduced in AtCASP-ΔCC lines. Using a dual-colour optical trapping system and a TIRF-tweezer system, individual Golgi bodies were captured in planta. Golgi bodies in AtCASP-ΔCC lines were easier to trap, and the ER-Golgi connection was more easily disrupted. Occasionally, the ER tubule followed a trapped Golgi body with a gap, indicating the presence of other tethering factors. Our work confirms that the intimate ER-Golgi association can be disrupted or weakened by expression of truncated AtCASP-ΔCC, and suggests that this connection is most likely maintained by a golgin-mediated tethering complex.HighlightHere we show that the Golgi-associated Arabidopsis thaliana protein AtCASP may form part of a golgin-mediated tethering complex involved in anchoring plant Golgi stacks to the endoplasmic reticulum (ER).

scholarly journals The pattern of appearance of enzymic activity during the development of the Golgi apparatus in amoebae

1978 ◽  
Vol 34 (1) ◽  
pp. 53-63
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Enzymic Activity ◽  
Nuclear Transplantation ◽  
Similar Distribution ◽  
Cytochemical Staining ◽  
Light Reaction ◽  
Golgi Bodies ◽  
Golgi Membranes

The appearance of enzymic activity during the development of the Golgi apparatus was studied by cytochemical staining of renucleated amoebae. In cells enucleated for 4 days, there was a great decline in size and number of Golgi bodies, or dictyosomes. Subsequent renucleation by nuclear transplantation resulted in a regeneration of Golgi bodies. Samples of amoebae were fixed and incubated for cytochemical staining at intervals of 1, 6, or 24 h after renucleation. Enzymes selected for study were guanosine diphosphatase (GDPase), esterase, and thiamine pyrophosphatase (TPPase). All three were found in the Golgi apparatus of normal amoebae but they differed in their overall intracellular distribution. GDPase was normally present at the convex pole of the Golgi apparatus, in rough endoplasmic reticulum, and in the nuclear envelope. In amoebae renucleated for 1 h, light reaction product for GDPase was present throughout the small stacks of cisternae that represented the forming Golgi apparatus. By 6 h following the operation GDPase reaction product was concentrated at the convex pole of the Golgi apparatus. Esterase, which was distributed throughout the stacks of normal Golgi cisternae, displayed a similar distribution in the forming Golgi bodies as soon as they were visible. TPPase was normally present in the Golgi apparatus but was not found in the endoplasmic reticulum. In contrast to the other enzymes, TPPase reaction product was absent from the forming Golgi apparatus 1 and 6 h after renucleation, and did not appear in the Golgi apparatus until 24 h after operation. Thus, enzymes held in common between the rough endoplasmic reticulum and the Golgi apparatus were present in the forming Golgi apparatus as soon as it was detectable, but an enzyme cytochemically localized to the Golgi apparatus only appeared later in development of the organelle. It is suggested that Golgi membranes might be derived from the endoplasmic reticulum and thus immediately contain endoplasmic reticulum enzymes, while Golgi-specific enzymes are added later in development.

scholarly journals Initial embedding of TRANSPARENT TESTA GLABRA 1 in the Arabidopsis thaliana flowering time regulatory pathway

2019 ◽  
Author(s):  
Barbara A M Paffendorf ◽  
Rawan Qassrawi ◽  
Andrea M Meys ◽  
Laura Trimborn ◽  
Andrea Schrader
Keyword(s):  
Arabidopsis Thaliana ◽  
Circadian Clock ◽  
Flowering Time ◽  
Response Regulator ◽  
Regulatory Pathway ◽  
In Planta ◽  
Transcript Levels ◽  
Transparent Testa ◽  
Flowering Locus

Pleiotropic regulatory factors mediate concerted responses of the plant’s trait network to endogenous and exogenous cues. TRANSPARENT TESTA GLABRA 1 (TTG1) is a pleiotropic regulator that has been predominantly described in its role as a regulator of early accessible developmental traits. Although its closest homologs LIGHT-REGULATED WD1 (LWD1) and LWD2 are regulators of photoperiodic flowering, a role of TTG1 in flowering time regulation has not been reported. Here we reveal that TTG1 is a regulator of flowering time in Arabidopsis thaliana and changes transcription levels of different targets within the flowering time regulatory pathway. TTG1 mutants flower early and TTG1 overexpression lines flower late at long-day conditions. Consistently, TTG1 can suppress the transcript levels of the floral integrators FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CO1 and can act as an activator of circadian clock components. Moreover, TTG1 might form feedback loops at the protein level. The TTG1 protein interacts with PSEUDO RESPONSE REGULATOR (PRR)s and basic HELIX-LOOP-HELIX 92 (bHLH92) in yeast. In planta, the respective pairs exhibit interesting patterns of localization including a recruitment of TTG1 by PRR5 to subnuclear foci. This mechanism proposes additional layers of regulation by TTG1 and might aid to specify the function of bHLH92. Within another branch of the pathway, TTG1 can elevate FLOWERING LOCUS C (FLC) transcript levels. FLC mediates signals from the vernalization, ambient temperature and autonomous pathway and the circadian clock is pivotal for the plant to synchronize with diurnal cycles of environmental stimuli like light and temperature. Our results suggest an unexpected positioning of TTG1 upstream of FLC and upstream of the circadian clock. In this light, this points to an adaptive value of the role of TTG1 in respect to flowering time regulation.

Suggested role of the Golgi apparatus and endoplasmic reticulum for crucial sites of hepatitis C virus replication in human lymphoblastoid cells infected in vitro

2003 ◽  
Vol 70 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Annalucia Serafino ◽  
Maria Beatrice Valli ◽  
Federica Andreola ◽  
Annalisa Crema ◽  
Giampietro Ravagnan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Golgi Apparatus ◽  
Virus Replication ◽  
Lymphoblastoid Cells

scholarly journals TRANSPARENT TESTA GLABRA 1 participates in flowering time regulation in Arabidopsis thaliana

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8303 ◽  
Author(s):  
Barbara A.M. Paffendorf ◽  
Rawan Qassrawi ◽  
Andrea M. Meys ◽  
Laura Trimborn ◽  
Andrea Schrader
Keyword(s):  
Arabidopsis Thaliana ◽  
Circadian Clock ◽  
Flowering Time ◽  
Response Regulator ◽  
In Planta ◽  
Transcript Levels ◽  
Autonomous Pathway ◽  
Transparent Testa ◽  
Flowering Locus

Pleiotropic regulatory factors mediate concerted responses of the plant’s trait network to endogenous and exogenous cues. TRANSPARENT TESTA GLABRA 1 (TTG1) is such a factor that has been predominantly described as a regulator of early developmental traits. Although its closest homologs LIGHT-REGULATED WD1 (LWD1) and LWD2 affect photoperiodic flowering, a role of TTG1 in flowering time regulation has not been reported. Here we reveal that TTG1 is a regulator of flowering time in Arabidopsis thaliana and changes transcript levels of different targets within the flowering time regulatory pathway. TTG1 mutants flower early and TTG1 overexpression lines flower late at long-day conditions. Consistently, TTG1 can suppress the transcript levels of the floral integrators FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CO1 and can act as an activator of circadian clock components. Moreover, TTG1 might form feedback loops at the protein level. The TTG1 protein interacts with PSEUDO RESPONSE REGULATOR (PRR)s and basic HELIX-LOOP-HELIX 92 (bHLH92) in yeast. In planta, the respective pairs exhibit interesting patterns of localization including a recruitment of TTG1 by PRR5 to subnuclear foci. This mechanism proposes additional layers of regulation by TTG1 and might aid to specify the function of bHLH92. Within another branch of the pathway, TTG1 can elevate FLOWERING LOCUS C (FLC) transcript levels. FLC mediates signals from the vernalization, ambient temperature and autonomous pathway and the circadian clock is pivotal for the plant to synchronize with diurnal cycles of environmental stimuli like light and temperature. Our results suggest an unexpected positioning of TTG1 upstream of FLC and upstream of the circadian clock. In this light, this points to an adaptive value of the role of TTG1 in respect to flowering time regulation.

scholarly journals Role of Disulfide Bridges Formed in the Luminal Domain of ATF6 in Sensing Endoplasmic Reticulum Stress

2006 ◽  
Vol 27 (3) ◽  
pp. 1027-1043 ◽  
Author(s):  
Satomi Nadanaka ◽  
Tetsuya Okada ◽  
Hiderou Yoshida ◽  
Kazutoshi Mori
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Golgi Apparatus ◽  
Er Stress ◽  
Disulfide Bridges ◽  
Sequential Action ◽  
Er Chaperone ◽  
Glycosylation Inhibitor ◽  
Membrane Bound

ABSTRACT ATF6 is a membrane-bound transcription factor activated by proteolysis in response to endoplasmic reticulum (ER) stress to induce the transcription of ER chaperone genes. We show here that, owing to the presence of intra- and intermolecular disulfide bridges formed between the two conserved cysteine residues in the luminal domain, ATF6 occurs in unstressed ER in monomer, dimer, and oligomer forms. Disulfide-bonded ATF6 is reduced upon treatment of cells with not only the reducing reagent dithiothreitol but also the glycosylation inhibitor tunicamycin, and the extent of reduction correlates with that of activation. Although reduction is not sufficient for activation, fractionation studies show that only reduced monomer ATF6 reaches the Golgi apparatus, where it is cleaved by the sequential action of the two proteases S1P and S2P. Reduced monomer ATF6 is found to be a better substrate than disulfide-bonded forms for S1P. ER stress-induced reduction is specific to ATF6 as the oligomeric status of a second ER membrane-bound transcription factor, LZIP/Luman, is not changed upon tunicamycin treatment and LZIP/Luman is well cleaved by S1P in the absence of ER stress. This mechanism ensures the strictness of regulation, in that the cell can only process ATF6 which has experienced the changes in the ER.

scholarly journals Dynein Supports Motility of Endoplasmic Reticulum in the FungusUstilago maydis

2002 ◽  
Vol 13 (3) ◽  
pp. 965-977 ◽  
Author(s):  
Roland Wedlich-Söldner ◽  
Irene Schulz ◽  
Anne Straube ◽  
Gero Steinberg
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Intracellular Transport ◽  
Fluorescent Protein ◽  
Brefeldin A ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Minor Importance ◽  
Dependent Transport

The endoplasmic reticulum (ER) of most vertebrate cells is spread out by kinesin-dependent transport along microtubules, whereas studies in Saccharomyces cerevisiae indicated that motility of fungal ER is an actin-based process. However, microtubules are of minor importance for organelle transport in yeast, but they are crucial for intracellular transport within numerous other fungi. Herein, we set out to elucidate the role of the tubulin cytoskeleton in ER organization and dynamics in the fungal pathogen Ustilago maydis. An ER-resident green fluorescent protein (GFP)-fusion protein localized to a peripheral network and the nuclear envelope. Tubules and patches within the network exhibited rapid dynein-driven motion along microtubules, whereas conventional kinesin did not participate in ER motility. Cortical ER organization was independent of microtubules or F-actin, but reformation of the network after experimental disruption was mediated by microtubules and dynein. In addition, a polar gradient of motile ER-GFP stained dots was detected that accumulated around the apical Golgi apparatus. Both the gradient and the Golgi apparatus were sensitive to brefeldin A or benomyl treatment, suggesting that the gradient represents microtubule-dependent vesicle trafficking between ER and Golgi. Our results demonstrate a role of cytoplasmic dynein and microtubules in motility, but not peripheral localization of the ER inU. maydis.

Memoirs: Variations in the Form of the Golgi Bodies during the Development of Neurones

1925 ◽  
Vol s2-69 (275) ◽  
pp. 509-517
Author(s):  
A. SUBBA RAU ◽  
R. J. LUDFORD
Keyword(s):  
Spinal Cord ◽  
Golgi Apparatus ◽  
Ganglion Cells ◽  
Early Stage ◽  
Golgi Body ◽  
Spinal Ganglia ◽  
Golgi Bodies ◽  
Stage Of Development ◽  
The Central Nervous System ◽  
High Degree

1. In the spinal ganglia of the chick of four days the Golgi apparatus or body is in the form of a cluster of granules or rodlets, grouped around the centrosphere, at one side of the nucleus (fig. 1, Pl. 39). 2. In a seven-day chick the Golgi body has increased in size and has begun to spread farther around the nucleus (fig. 3, Pl. 39). 3. All ganglion cells examined, both those of the spinal cord and of ganglia, have the Golgi apparatus in this compacted form during their early stage. 4. At a certain period which varies in the different cells the apparatus spreads out in the cytoplasm (fig. 4, Pl. 39), so that in the adult ganglia the apparatus is more or less scattered throughout the cell (figs. 5, 6, and 7, Pl. 39). 5. It is uncertain to what extent variations in the form of the apparatus, whether reticulate or in the form of individual rodlets, are due to differences in the degree of impregnation with the silver. The plane of the section is also an important factor in determining the appearance presented by the apparatus. 6. The medullary cells of the suprarenal body, which are derived from the central nervous system, have the apparatus in the form of a coiled network or cluster of granules at one pole of the nucleus, similar to the cells of the spinal ganglia at the early stage of development. 7. It is suggested that the scattered form of the Golgi apparatus in adult ganglion cells is an expression of the high degree of metabolism existing in these cells.

scholarly journals The plant endoplasmic reticulum: a cell-wide web

2009 ◽  
Vol 423 (2) ◽  
pp. 145-155 ◽  
Author(s):  
Imogen A. Sparkes ◽  
Lorenzo Frigerio ◽  
Nicholas Tolley ◽  
Chris Hawes
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Actin Cytoskeleton ◽  
Higher Plants ◽  
Direct Interaction ◽  
Present Review ◽  
A Cell ◽  
Myosin Motors

The ER (endoplasmic reticulum) in higher plants forms a pleomorphic web of membrane tubules and small cisternae that pervade the cytoplasm, but in particular form a polygonal network at the cortex of the cell which may be anchored to the plasma membrane. The network is associated with the actin cytoskeleton and demonstrates extensive mobility, which is most likely to be dependent on myosin motors. The ER is characterized by a number of domains which may be associated with specific functions such as protein storage, or with direct interaction with other organelles such as the Golgi apparatus, peroxisomes and plastids. In the present review we discuss the nature of the network, the role of shape-forming molecules such as the recently described reticulon family of proteins and the function of some of the major domains within the ER network.

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