Reticulon 4a/NogoA locates to regions of high membrane curvature and may have a role in nuclear envelope growth

Киселева, Елена; Morozova, Ksenia N.; Voeltz, Gia K.; Allen, Terrence D.; Goldberg, Martin W.

doi:10.1016/j.jsb.2007.08.005

Cited by 48 publications

(57 citation statements)

References 37 publications

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“…In fact, Rtns are not only specifically localized to tubular ER domains but also to the edges of cisternae and edges of the fenestra found within cisternae (Fig. 1D,E) (Kiseleva et al 2007;Schuck et al 2009;Shibata et al 2010). Consistent with this localization, yeast cells in which Rtn/Yop1 have been deleted lack tubules but also contain expansive cisternae that are no longer fenestrated .…”

mentioning

confidence: 59%

Endoplasmic Reticulum Structure and Interconnections with Other Organelles

English

Voeltz

2013

Cold Spring Harbor Perspectives in Biology

286

220

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The endoplasmic reticulum (ER) is a large, continuous membrane-bound organelle comprised of functionally and structurally distinct domains including the nuclear envelope, peripheral tubular ER, peripheral cisternae, and numerous membrane contact sites at the plasma membrane, mitochondria, Golgi, endosomes, and peroxisomes. These domains are required for multiple cellular processes, including synthesis of proteins and lipids, calcium level regulation, and exchange of macromolecules with various organelles at ER-membrane contact sites. The ER maintains its unique overall structure regardless of dynamics or transfer at ER-organelle contacts. In this review, we describe the numerous factors that contribute to the structure of the ER.T he endoplasmic reticulum (ER) is a dynamic organelle responsible for many cellular functions, including the synthesis of proteins and lipids, and regulation of intracellular calcium levels. This review focuses on the distinct and complex morphology of the ER. The structure of the ER is complex because of the numerous distinct domains that exist within one continuous membrane bilayer. These domains are shaped by interactions with the cytoskeleton, by proteins that stabilize membrane shape, and by a homotypic fusion machinery that allows the ER membrane to maintain its continuity and identity. The ER also contains domains that contact the plasma membrane (PM) and other organelles including the Golgi, endosomes, mitochondria, lipid droplets, and peroxisomes. ER contact sites with other organelles and the PM are both abundant and dispersed throughout the cytoplasm, suggesting that they too could influence the overall architecture of the ER. As we will discuss here, ER shape and distribution are regulated by many intrinsic and extrinsic forces. ER STRUCTURE AND FORMATION Domains of the ER Are Stabilized by Membrane-Shaping ProteinsThe endoplasmic reticulum (ER) is a large membrane-bound compartment spread throughout the cytoplasm of eukaryotic cells. It is divided into three major morphologies that include the nuclear envelope (NE), peripheral ER cisternae, and an interconnected tubular network

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mentioning

confidence: 59%

Endoplasmic Reticulum Structure and Interconnections with Other Organelles

English

Voeltz

2013

Cold Spring Harbor Perspectives in Biology

286

220

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“…Deletion of both RTN1 and YOP1, encoding two of the reticulons of S. cerevisiae, causes defects in nucleoporin localization and NPC distribution within the NE (10). In metazoan cells, reticulons are required for proper reassembly of the NE following mitosis (41,42). Using a Xenopus laevis in vitro system where de novo assembly of new NPCs takes place, Dawson et al (2009) showed that addition of an anti-reticulon antibody to the system led to a block in the assembly of new NPCs (10).…”

Section: Discussionmentioning

confidence: 99%

Yeast Integral Membrane Proteins Apq12, Brl1, and Brr6 Form a Complex Important for Regulation of Membrane Homeostasis and Nuclear Pore Complex Biogenesis

et al. 2015

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bProper functioning of intracellular membranes is critical for many cellular processes. A key feature of membranes is their ability to adapt to changes in environmental conditions by adjusting their composition so as to maintain constant biophysical properties, including fluidity and flexibility. Similar changes in the biophysical properties of membranes likely occur when intracellular processes, such as vesicle formation and fusion, require dramatic changes in membrane curvature. Similar modifications must also be made when nuclear pore complexes (NPCs) are constructed within the existing nuclear membrane, as occurs during interphase in all eukaryotes. Here we report on the role of the essential nuclear envelope/endoplasmic reticulum (NE/ER) protein Brl1 in regulating the membrane composition of the NE/ER. We show that Brl1 and two other proteins characterized previously-Brr6, which is closely related to Brl1, and Apq12-function together and are required for lipid homeostasis. All three transmembrane proteins are localized to the NE and can be coprecipitated. As has been shown for mutations affecting Brr6 and Apq12, mutations in Brl1 lead to defects in lipid metabolism, increased sensitivity to drugs that inhibit enzymes involved in lipid synthesis, and strong genetic interactions with mutations affecting lipid metabolism. Mutations affecting Brl1 or Brr6 or the absence of Apq12 leads to hyperfluid membranes, because mutant cells are hypersensitive to agents that increase membrane fluidity. We suggest that the defects in nuclear pore complex biogenesis and mRNA export seen in these mutants are consequences of defects in maintaining the biophysical properties of the NE. T he nuclear envelope (NE) of eukaryotic cells compartmentalizes the nuclear material and separates it from the cytoplasm. The double membrane of the NE consists of an outer and an inner nuclear membrane (ONM and INM) that differ in protein and lipid composition. The NE is structurally and functionally related to the endoplasmic reticulum (ER), and the ONM is contiguous with the ER (1, 2). Embedded in the NE are the nuclear pore complexes (NPCs) and, in budding yeast, the spindle pole body (SPB). NPCs are extremely large and are constructed from multiple copies of about 30 different nucleoporins (nups) (3, 4). NPCs mediate selective trafficking of proteins and other macromolecules between the nucleus and the cytoplasm but also serve other important functions, including gene activation and mRNA surveillance (5, 6). The biogenesis of NPCs and their distribution over the NE are highly regulated processes and are coordinated with the cell cycle (7). During interphase, the number of NPCs doubles. In budding yeast, the NE remains intact throughout the cell cycle, and all the formation of NPCs occurs through de novo construction within the NE.In addition to the ONM and the INM, the NE contains a pore membrane domain (POM), formed by the fusion of the INM and ONM at sites where NPCs are assembled (8). The POM is a highly curved region of the NE that is i...

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“…The ER exists as a continuous meshwork of membrane sheets and membrane tubules. Proteins known as reticulons cause tubule formation in the ER (Voeltz et al, 2006), and high levels of reticulons are inhibitory to nuclear growth, which suggests that the availability of membrane in the form of sheets can put an upper limit on nuclear size (Anderson and Hetzer, 2008;Kiseleva et al, 2007). Work in the Xenopus system has demonstrated a requirement for NPCs and nuclear import in nuclear growth after NE assembly (D'Angelo et al, 2006;Newport et al, 1990), which suggests that the import of one or more nuclear proteins contributes to sizing the nucleus.…”

Section: Factors That Affect Nuclear Volumementioning

confidence: 99%

Sizing up the nucleus: nuclear shape, size and nuclear-envelope assembly

Webster

Witkin

Cohen-Fix

2009

Journal of Cell Science

377

342

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The nucleus is one of the most prominent cellular organelles, yet surprisingly little is known about how it is formed, what determines its shape and what defines its size. As the nuclear envelope (NE) disassembles in each and every cell cycle in metazoans, the process of rebuilding the nucleus is crucial for proper development and cell proliferation. In this Commentary, we summarize what is known about the regulation of nuclear shape and size, and highlight recent findings that shed light on the process of building a nucleus, including new discoveries related to NE assembly and the relationship between the NE and the endoplasmic reticulum (ER). Throughout our discussion, we note interesting aspects of nuclear structure that have yet to be resolved. Finally, we present an idea -which we refer to as 'the limited flat membrane hypothesis' -to explain the formation of a single nucleus that encompasses of all of the cell's chromosomes following mitosis. Nuclear shapeThe nuclei of most cells are either round or oval. This, in itself, is hardly remarkable except for the fact that various diseases, as well as aging, are associated with alterations in nuclear shape (Fig. 3). Moreover, in certain specialized cell types, altered nuclear shape is important for cell function. But what determines nuclear shape, and how does shape affect function? In many cell types, altered nuclear shape is due to changes in the nuclear lamina. In some cases, however, the shape of the nucleus is altered by forces that act from the cytoplasm. In either case, it is still not entirely clear how nuclear shape affects function, although two main hypotheses exist. The first hypothesis posits that changes in nuclear shape alter the rigidity of the nucleus; this could be beneficial for cells that need to squeeze through tight spaces, but deleterious to cells that are under mechanical duress. The second hypothesis proposes that changes in nuclear shape result in chromatin reorganization and thereby affect gene expression. It is important to note that these two hypotheses are not mutually exclusive. In addition, because nuclear shape changes are often accompanied by an altered nuclear lamina, it is possible that the dramatic effect on cell function is due to aberrant properties of the lamina rather than nuclear shape changes per se. In this section, we examine some of the cell types and conditions that are associated with irregular nuclear shape, and we discuss, when known, the causes of these shape changes and how they affect cell function. Normal cells with abnormal nucleiOf all the cell types that normally exhibit unusual nuclear shape, neutrophils have been studied the most thoroughly. Neutrophils are cells of the immune system that migrate through tissue towards sites of infection. They are characterized by their multi-lobed nuclei, typically exhibiting three or four lobes that are connected by thin DNA-containing filaments ( Fig. 3B) (reviewed by Hoffmann et al., 2007). Neutrophils with hypolobulated nuclei are associated with Pelger-Huet anoma...

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Reticulon 4a/NogoA locates to regions of high membrane curvature and may have a role in nuclear envelope growth

Cited by 48 publications

References 37 publications

Endoplasmic Reticulum Structure and Interconnections with Other Organelles

Endoplasmic Reticulum Structure and Interconnections with Other Organelles

Yeast Integral Membrane Proteins Apq12, Brl1, and Brr6 Form a Complex Important for Regulation of Membrane Homeostasis and Nuclear Pore Complex Biogenesis

Sizing up the nucleus: nuclear shape, size and nuclear-envelope assembly

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