Involvement of the Actin Cytoskeleton and Homotypic Membrane Fusion in ER Dynamics in<i>Caenorhabditis elegans</i>

Poteryaev, Dmitry; Squirrell, Jayne M.; Campbell, Jay M.; White, John; Spang, Anne

doi:10.1091/mbc.e04-08-0726

Cited by 140 publications

(190 citation statements)

References 53 publications

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“…These observations indicate that ER tubulation might be an experimental artifact due to chemical fixation of cells, in which the ER has been depleted of attached ribosomes during mitosis or by puromycin treatment. 4) Finally, we note that curvilinear ER profiles, very similar to ours, were observed by fluorescence confocal microscopy during mitosis in developing embryos of C. elegans, and analysis of the 3D images led to the conclusion that the ER forms sheets (Poteryaev et al, 2005). Therefore, we propose that the ER undergoes a transformation during cell division, from a network of cisternae and tubules characteristic of cells in interphase, to an organization dominated by extended cisternae during mitosis.…”

Section: Discussionsupporting

confidence: 78%

“…These include the ER markers Sec61␤ (Anderson and Hetzer, 2007; this work); ss-GFP (or RFP)-KDEL (Terasaki, 2000;Altan-Bonnet et al, 2006;this work); ␤-galactosyltransferase (Terasaki, 2000;Altan-Bonnet et al, 2006;this work); reticulon4HD (this work); ER Tracker Red (this work); SP12 (Poteryaev et al, 2005), PDI (Bobinnec et al, 2003); and the nuclear envelope markers emerin (this work), LBR (Ellenberg et al, 1997;this work), and POM121, gp210 (Anderson and Hetzer, 2007). In all cases, the pattern within a single optical section always seems as long, smooth, curvilinear tracings spanning 3 m or more.…”

Section: Discussionmentioning

confidence: 99%

“…Such studies are challenging, because of the complex, three-dimensional morphology of the ER and because of the rapidity of the changes in cell organization that accompany cell division. A recent live-cell imaging study, which used the signal peptidase SP12 fused to green fluorescent protein (GFP) to follow ER dynamics during early Caenorhabditis elegans embryogenesis, found that the mitotic ER contains extensive, sheet-like structures (Poteryaev et al, 2005). A different morphological study, which used electron microscopy to visualize at higher resolution the osmium-stained ER membranes of mitotic HeLa cells, also found that the mitotic ER maintains a cisternal organization; indeed, the electron micrographs show dramatic curvilinear ER tracing within the plane of the section (McCullough and Lucocq, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Cisternal Organization of the Endoplasmic Reticulum during Mitosis

Lü

Ladinsky

Kirchhausen

2009

MBoC

205

221

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The endoplasmic reticulum (ER) of animal cells is a single, dynamic, and continuous membrane network of interconnected cisternae and tubules spread out throughout the cytosol in direct contact with the nuclear envelope. During mitosis, the nuclear envelope undergoes a major rearrangement, as it rapidly partitions its membrane-bound contents into the ER. It is therefore of great interest to determine whether any major transformation in the architecture of the ER also occurs during cell division. We present structural evidence, from rapid, live-cell, three-dimensional imaging with confirmation from high-resolution electron microscopy tomography of samples preserved by high-pressure freezing and freeze substitution, unambiguously showing that from prometaphase to telophase of mammalian cells, most of the ER is organized as extended cisternae, with a very small fraction remaining organized as tubules. In contrast, during interphase, the ER displays the familiar reticular network of convolved cisternae linked to tubules.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cisternal Organization of the Endoplasmic Reticulum during Mitosis

Lü

Ladinsky

Kirchhausen

2009

MBoC

205

221

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“…Later, evidence was presented that Cdc48 works in conjunction with the ER-localized target-soluble NSF attachment protein (SNAP) receptor (t-SNARE) Ufe1p [14]. Subsequent work has confirmed the role of p97 in the dynamics of ER architecture [15,16], but also indicates the participation of additional mechanisms. Thus, antibodies against p97 or its cofactors only partially disrupt ER organization in living cells [17] or in cell-free reconstituted systems [18].…”

Section: Homotypic Fusionmentioning

confidence: 99%

Endoplasmic reticulum architecture: structures in flux

Borgese

Francolini

Snapp

2006

Current Opinion in Cell Biology

206

147

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The endoplasmic reticulum (ER) is a dynamic pleiomorphic organelle containing continuous but distinct subdomains. The diversity of ER structures parallels its many functions, including secretory protein biogenesis, lipid synthesis, drug metabolism and Ca 2+ signaling. Recent studies are revealing how elaborate ER structures arise in response to subtle changes in protein levels, dynamics, and interactions as well as in response to alterations in cytosolic ion concentrations. Subdomain formation appears to be governed by principles of self-organization. Once formed, ER subdomains remain malleable and can be rapidly transformed into alternative structures in response to altered conditions. The mechanisms that modulate ER structure are likely to be important for the generation of the characteristic shapes of other organelles.

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“…The ER is normally relatively evenly distributed in interphase embryos and then condenses to form patches as embryos enter mitosis (Poteryaev et al 2005;Audhya et al 2007). ER morphology was noticeably altered in cnep-1D embryos with prominent ER patches apparent prior to the onset of mitosis (Fig.…”

Section: Spatial Control Of Phospholipid Flux Allows Nebd Genes and Devmentioning

confidence: 99%

Spatial control of phospholipid flux restricts endoplasmic reticulum sheet formation to allow nuclear envelope breakdown

et al. 2014

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The nuclear envelope is a subdomain of the endoplasmic reticulum (ER). Here we characterize CNEP-1 (CTD [Cterminal domain] nuclear envelope phosphatase-1), a nuclear envelope-enriched activator of the ER-associated phosphatidic acid phosphatase lipin that promotes synthesis of major membrane phospholipids over phosphatidylinositol (PI). CNEP-1 inhibition led to ectopic ER sheets in the vicinity of the nucleus that encased the nuclear envelope and interfered with nuclear envelope breakdown (NEBD) during cell division. Reducing PI synthesis suppressed these phenotypes, indicating that CNEP-1 spatially regulates phospholipid flux, biasing it away from PI production in the vicinity of the nuclear envelope to prevent excess ER sheet formation and NEBD defects.Supplemental material is available for this article.Received September 11, 2013; revised version accepted December 13, 2013. The endoplasmic reticulum (ER) is composed of sheets and tubules bounded by a membrane bilayer that faces the cytoplasm on one side and an internal lumen on the other. The ER is partitioned into subdomains specialized for different functions. The nuclear envelope subdomain is a spherical sheet perforated by nuclear pores that encases the chromatin. The outer membrane and lumen of the nuclear envelope are directly contiguous with other ER structural elements, whereas passage of proteins to the inner nuclear membrane (INM) is gated by the nuclear pores (Hetzer 2010;English and Voeltz 2013). The chromatin-facing INM is associated with the nuclear lamina, a dense filament meshwork that provides structural support (Hetzer 2010;Gerace and Huber 2012).The ER also serves as a platform for de novo phospholipid synthesis (Fagone and Jackowski 2009;Lagace and Ridgway 2013). A central player is the conserved phosphatase lipin, which converts phosphatidic acid (PA) to diacylglycerol (DAG) Siniossoglou 2013). In metazoans, lipin is at a branching point in the phospholipid synthesis pathway; the major building blocks of membrane bilayers (phosphatidylcholine [PC] and phosphatidylethanolamine [PE]) are synthesized from the lipin product DAG, whereas phosphatidylinositol (PI) is synthesized from the lipin substrate PA Lagace and Ridgway 2013;Siniossoglou 2013). PI is converted to phosphoinositides (PIPs) when transported to other organelles that house specific PIP kinases and phosphatases (Balla 2013). Within the ER, PC and PE make up >70% of total phospholipid, whereas PI makes up <10% (van Meer et al. 2008). In metazoans, decreased lipin activity is predicted to shift phospholipid flux away from production of DAG and the major membrane phospholipids PC and PE toward the production of PI. This is in contrast to budding yeast, where a pathway that is not present in metazoans (the CDP-DAG pathway) (Supplemental Fig. S1A) converts PA to major membrane phospholipids (Carman and Han 2011;Siniossoglou 2013). Thus, lipin inhibition in budding yeast leads to an increase in all phospholipids and an abnormal expansion of the nuclear envelope that does not occu...

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Involvement of the Actin Cytoskeleton and Homotypic Membrane Fusion in ER Dynamics inCaenorhabditis elegans

Cited by 140 publications

References 53 publications

Cisternal Organization of the Endoplasmic Reticulum during Mitosis

Cisternal Organization of the Endoplasmic Reticulum during Mitosis

Endoplasmic reticulum architecture: structures in flux

Spatial control of phospholipid flux restricts endoplasmic reticulum sheet formation to allow nuclear envelope breakdown

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