scholarly journals Analysis of De Novo Golgi Complex Formation after Enzyme-based Inactivation

2007 ◽  
Vol 18 (11) ◽  
pp. 4637-4647 ◽  
Author(s):  
Florence Jollivet ◽  
Graça Raposo ◽  
Ariane Dimitrov ◽  
Rachid Sougrat ◽  
Bruno Goud ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
De Novo ◽  
Living Cells ◽  
Integrative Model ◽  
Interphase Cells ◽  
Golgi Structure ◽  
Dynamics And Function ◽  
And Function ◽  
Drug Free

The Golgi complex is characterized by its unique morphology of closely apposed flattened cisternae that persists despite the large quantity of lipids and proteins that transit bidirectionally. Whether such a structure is maintained through endoplasmic reticulum (ER)-based recycling and auto-organization or whether it depends on a permanent Golgi structure is strongly debated. To further study Golgi maintenance in interphase cells, we developed a method allowing for a drug-free inactivation of Golgi dynamics and function in living cells. After Golgi inactivation, a new Golgi-like structure, containing only certain Golgi markers and newly synthesized cargos, was produced. However, this structure did not acquire a normal Golgi architecture and was unable to ensure a normal trafficking activity. This suggests an integrative model for Golgi maintenance in interphase where the ER is able to autonomously produce Golgi-like structures that need pre-existing Golgi complexes to be organized as morphologically normal and active Golgi elements.

scholarly journals Modulating dynamics and function of nuclear actin with synthetic bicyclic peptides

2020 ◽  
Author(s):  
Nanako Machida ◽  
Daisuke Takahashi ◽  
Yuya Ueno ◽  
Yoshihiro Nakama ◽  
Raphael J Gubeli ◽  
...  
Keyword(s):  
Regulation Of Gene Expression ◽  
Living Cells ◽  
Actin Binding ◽  
Nuclear Actin ◽  
Dna Double Strand Breaks ◽  
Cytoplasmic Actin ◽  
Localization Signal ◽  
Dynamics And Function ◽  
And Function ◽  
Analytical Tools

Abstract Actin exists in monomeric globular (G-) and polymerized filamentous (F-) forms and the dynamics of its polymerization/depolymerization are tightly regulated in both the cytoplasm and the nucleus. Various essential functions of nuclear actin have been identified including regulation of gene expression and involvement in the repair of DNA double-strand breaks (DSB). Small G-actin-binding molecules affect F-actin formation and can be utilized for analysis and manipulation of actin in living cells. However, these G-actin-binding molecules are obtained by extraction from natural sources or through complex chemical synthesis procedures, and therefore, the generation of their derivatives for analytical tools is underdeveloped. In addition, their effects on nuclear actin cannot be separately evaluated from those on cytoplasmic actin. Previously, we have generated synthetic bicyclic peptides, consisting of two macrocyclic rings, which bind to G-actin but not to F-actin. Here, we describe the introduction of these bicyclic peptides into living cells. Furthermore, by conjugation to a nuclear localization signal (NLS), the bicyclic peptides accumulated in the nucleus. The NLS-bicyclic peptides repress the formation of nuclear F-actin, and impair transcriptional regulation and DSB repair. These observations highlight a potential role for NLS-linked bicyclic peptides in the manipulation of dynamics and functions of nuclear actin.

scholarly journals Golgi spectrin: identification of an erythroid beta-spectrin homolog associated with the Golgi complex.

1994 ◽  
Vol 127 (3) ◽  
pp. 707-723 ◽  
Author(s):  
K A Beck ◽  
J A Buchanan ◽  
V Malhotra ◽  
W J Nelson
Keyword(s):  
Golgi Complex ◽  
Structural Integrity ◽  
Functional Organization ◽  
Brefeldin A ◽  
Cell Types ◽  
Loss Of Function ◽  
Dynamic Relationship ◽  
Golgi Membranes ◽  
Golgi Structure ◽  
And Function

Spectrin is a major component of a membrane-associated cytoskeleton involved in the maintenance of membrane structural integrity and the generation of functionally distinct membrane protein domains. Here, we show that a homolog of erythrocyte beta-spectrin (beta I sigma*) co-localizes with markers of the Golgi complex in a variety of cell types, and that microinjected beta-spectrin codistributes with elements of the Golgi complex. Significantly, we show a dynamic relationship between beta-spectrin and the structural and functional organization of the Golgi complex. Disruption of both Golgi structure and function, either in mitotic cells or following addition of brefeldin A, is accompanied by loss of beta-spectrin from Golgi membranes and dispersal in the cytoplasm. In contrast, perturbation of Golgi structure without a loss of function, by the addition of nocodazole, results in retention of beta-spectrin with the dispersed Golgi elements. These results indicate that the association of beta-spectrin with Golgi membranes is coupled to Golgi organization and function.

A small GTPase involved in mitochondrial morphology and function

2015 ◽  
Vol 43 (1) ◽  
pp. 108-110 ◽  
Author(s):  
Anne Spang
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Essential Role ◽  
Small Gtpase ◽  
Mitochondrial Morphology ◽  
Interconnected Network ◽  
Contact Sites ◽  
Close Proximity ◽  
And Function ◽  
Adp Ribosylation Factor

Mitochondria are the powerhouse of cells as they produce the bulk of ATP which is consumed by the cell. They form a highly interconnected network that is governed by fission and fusion processes. In addition, mitochondria and the endoplasmic reticulum (ER) are found in close proximity to each other and it is thought that they maintain contact sites to exchange molecules. The regulation and the function of these contact sites need to be further explored. The small GTPase Arf1 (ADP-ribosylation factor 1), which is best known for its essential role in the generation of coatomer protein I (COPI)-coated vesicles at the Golgi complex appears to be also essential for the dynamics and maintenance of mitochondrial function, presumably at ER–mitochondrial contact sites.

Disruption of Golgi structure and function in mammalian cells expressing a mutant dynamin

2000 ◽  
Vol 113 (11) ◽  
pp. 1993-2002 ◽  
Author(s):  
H. Cao ◽  
H.M. Thompson ◽  
E.W. Krueger ◽  
M.A. McNiven
Keyword(s):  
Mammalian Cells ◽  
Living Cells ◽  
Dominant Negative ◽  
Coated Vesicle ◽  
Large Numbers ◽  
Golgi Structure ◽  
And Function ◽  
Golgi Network ◽  
Mutant Cells

The large GTPase dynamin is a mechanoenzyme that participates in the scission of nascent vesicles from the plasma membrane. Recently, dynamin has been demonstrated to associate with the Golgi apparatus in mammalian cells by morphological and biochemical methods. Additional studies using a well characterized, cell-free assay have supported these findings by demonstrating a requirement for dynamin function in the formation of clathrin-coated, and non-clathrin-coated vesicles from the trans-Golgi network (TGN). In this study, we tested if dynamin participates in Golgi function in living cells through the expression of a dominant negative dynamin construct (K44A). Cells co-transfected to express this mutant dynamin and a GFP-tagged Golgi resident protein (TGN38) exhibit Golgi structures that are either compacted, vesiculated, or tubulated. Electron microscopy of these mutant cells revealed large numbers of Golgi stacks comprised of highly tubulated cisternae and an extraordinary number of coated vesicle buds. Cells expressing mutant dynamin and GFP-tagged VSVG demonstrated a marked retention (8- to 11-fold) of the nascent viral G-protein in the Golgi compared to control cells. These observations in living cells are consistent with previous morphological and in vitro studies demonstrating a role for dynamin in the formation of secretory vesicles from the TGN.

scholarly journals Fluorescent conjugates of brefeldin A selectively stain the endoplasmic reticulum and Golgi complex of living cells.

1995 ◽  
Vol 43 (9) ◽  
pp. 907-915 ◽  
Author(s):  
Y Deng ◽  
J R Bennink ◽  
H C Kang ◽  
R P Haugland ◽  
J W Yewdell
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Golgi Complex ◽  
Intracellular Transport ◽  
Brefeldin A ◽  
Living Cells ◽  
Vesicular Trafficking ◽  
Cellular Functions ◽  
Animal Cells ◽  
Specific Localization

The fungal metabolite brefeldin A (BFA) interferes with vesicular trafficking in most animal cells. To gain insight into the mechanism of BFA action, we esterified it to the fluorophore, boron dipyromethene difluoride (BODIPY). BODIPY-BEA localized predominantly in the endoplasmic reticulum (ER) and Golgi complex of viable cells and was extracted by detergent treatment, suggesting it interacts primarily with lipid bilayers. The localization of the conjugate is conferred by BFA, since free BODIPY or BODIPY esterified to cyclopentanol did not specifically localize to internal membranes. BODIPY-BFA exhibited a similar biological activity to BFA, but only when used at higher concentrations and after a delay. HPLC analysis revealed that over this period, cells converted BODIPY-BFA to species co-eluting with free BODIPY and BFA. Therefore, BODIPY-BFA is probably inactive until BFA is released by cellular esterases. The specific localization of BODIPY-BFA to the ER and Golgi complex suggests that BFA might exert its effects on vesicular trafficking by perturbing the lipid bilayer of its target organelles. Because BODIPY-BFA intensely stains the ER at concentrations that have no discernible effects on intracellular transport or other cellular functions, it should be useful for visualizing the ER in living cells.

scholarly journals The Intraflagellar Transport Protein IFT20 Is Associated with the Golgi Complex and Is Required for Cilia Assembly

2006 ◽  
Vol 17 (9) ◽  
pp. 3781-3792 ◽  
Author(s):  
John A. Follit ◽  
Richard A. Tuft ◽  
Kevin E. Fogarty ◽  
Gregory J. Pazour
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Basal Body ◽  
Binding Sites ◽  
Mammalian Cells ◽  
Intraflagellar Transport ◽  
Living Cells ◽  
Large Protein ◽  
Protein Particles ◽  
Golgi Structure

Eukaryotic cilia are assembled via intraflagellar transport (IFT) in which large protein particles are motored along ciliary microtubules. The IFT particles are composed of at least 17 polypeptides that are thought to contain binding sites for various cargos that need to be transported from their site of synthesis in the cell body to the site of assembly in the cilium. We show here that the IFT20 subunit of the particle is localized to the Golgi complex in addition to the basal body and cilia where all previous IFT particle proteins had been found. In living cells, fluorescently tagged IFT20 is highly dynamic and moves between the Golgi complex and the cilium as well as along ciliary microtubules. Strong knock down of IFT20 in mammalian cells blocks ciliary assembly but does not affect Golgi structure. Moderate knockdown does not block cilia assembly but reduces the amount of polycystin-2 that is localized to the cilia. This work suggests that IFT20 functions in the delivery of ciliary membrane proteins from the Golgi complex to the cilium.

scholarly journals Learning Naturalistic Temporal Structure in the Posterior Medial Network

2018 ◽  
Vol 30 (9) ◽  
pp. 1345-1365 ◽  
Author(s):  
Mariam Aly ◽  
Janice Chen ◽  
Nicholas B. Turk-Browne ◽  
Uri Hasson
Keyword(s):  
De Novo ◽  
Temporal Structure ◽  
Temporal Integration ◽  
Functional Coupling ◽  
Relative Role ◽  
Dynamics And Function ◽  
And Function ◽  
The Brain ◽  
Event Schemas

The posterior medial network is at the apex of a temporal integration hierarchy in the brain, integrating information over many seconds of viewing intact, but not scrambled, movies. This has been interpreted as an effect of temporal structure. Such structure in movies depends on preexisting event schemas, but temporal structure can also arise de novo from learning. Here, we examined the relative role of schema-consistent temporal structure and arbitrary but consistent temporal structure on the human posterior medial network. We tested whether, with repeated viewing, the network becomes engaged by scrambled movies with temporal structure. Replicating prior studies, activity in posterior medial regions was immediately locked to stimulus structure upon exposure to intact, but not scrambled, movies. However, for temporally structured scrambled movies, functional coupling within the network increased across stimulus repetitions, rising to the level of intact movies. Thus, temporal structure is a key determinant of network dynamics and function in the posterior medial network.

Sign in / Sign up

Export Citation Format

Share Document