Nucleus–vacuole junctions in yeast: anatomy of a membrane contact site

Kvam, Erik; Goldfarb, David S.

doi:10.1042/bst0340340

Cited by 45 publications

(48 citation statements)

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“…It is initiated at nucleus-vacuole (NV) junctions, highly localized membranemembrane contact zones at which membrane reorganization occurs (Kvam and Goldfarb, 2006;Krick et al, 2009;Dawaliby and Mayer, 2010). NV junctions are formed by interactions between Vac8, located in the vacuolar membrane, and Nvj1, in the nuclear envelope (step 1).…”

Section: Piecemeal Microautophagy Of the Nucleusmentioning

confidence: 99%

Nucleophagy at a glance

Mijaljica

Devenish

2013

Journal of Cell Science

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Under certain circumstances, the removal of damaged or non-essential parts of the nucleus, or even an entire nucleus, is crucial in order to promote cell longevity and enable proper function. A selective form of autophagy, known as nucleophagy, can be used to accomplish the degradation of nucleusderived material. In this Cell Science at a Glance article and the accompanying poster, we summarize the similarities and differences between the divergent modes of nucleophagy that have been described to date, emphasizing, where possible, the molecular mechanism, the membrane interactions and rearrangements, and the nature of the nucleus-derived material that is degraded. In turn, we will consider nucleophagy processes in the lower eukaryotes, the budding yeast Saccharomyces cerevisiae, filamentous fungi Aspergillus and Magnaporthe oryzae and the ciliated protozoan Tetrahymena thermophila, and finally in mammalian cells. We will also briefly discuss the emerging links between nucleophagy and human disease.

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Section: Piecemeal Microautophagy Of the Nucleusmentioning

confidence: 99%

Nucleophagy at a glance

Mijaljica

Devenish

2013

Journal of Cell Science

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“…Osh1p is thought to mediate sterol-dependent trafficking of the high-affinity tryptophan permease, Tat2p, that is routed to either the plasma membrane or the vacuole depending on the concentration of tryptophan in the medium. [90][91][92] Targeting of Osh1p to NV junctions is specified by the ankyrin repeat region; Osh1p is diffusely distributed in strains lacking either Nvj1p or Vac8p alone, implying that binding requires both Nvj1p and Vac8p. Targeting would seem to require correct formation of the NV junction structure, such that Osh1p binds only to the Nvj1p/Vac8p complex, or to some other factor recruited to this complex.…”

Section: A Second Form Of Autophagic Degradation Of the Yeast Nucleusmentioning

confidence: 99%

“…40,90,91,95,96 Whether Tsc13p requires Nvj1p or Vac8p for localization to NV junctions remains to be determined. VLCFAs are important constituents of several complex lipid species in yeast including ceramides, sphingolipids, inositolphospholipids and glycosylphosphatidylinositol anchors, and as such, play important roles in membrane and lipid raft biogenesis, membrane fluidity and thickness and cell signalling.…”

Section: A Second Form Of Autophagic Degradation Of the Yeast Nucleusmentioning

confidence: 99%

“…VLCFAs are important constituents of several complex lipid species in yeast including ceramides, sphingolipids, inositolphospholipids and glycosylphosphatidylinositol anchors, and as such, play important roles in membrane and lipid raft biogenesis, membrane fluidity and thickness and cell signalling. 40,90,91 The human homologue of Tsc13p, SC2, exhibits similar enoyl-CoA reductase activity during fatty acid elongation in vitro. 40,97 Vesicles, highly enriched in Tsc13p, are observed to bud off the NE into the lumen of the vacuole (these vesicles markedly resemble PMN vesicles) when cells enter stationary phase in the presence of non-fermentable carbon sources, or in elo2 and elo3 mutants (both genes are required for VLCFA synthesis) indicating that nuclear-vacuolar interactions may provide a preferred site for NE recycling.…”

Section: A Second Form Of Autophagic Degradation Of the Yeast Nucleusmentioning

confidence: 99%

“…In addition to mediating PMN, Nvj1p also functions in sequestering two conserved proteins, namely, Osh1p and Tsc13p, 40,90,91 with roles in lipid biosynthesis and trafficking to the NV junctions. Osh1p is thought to mediate sterol-dependent trafficking of the high-affinity tryptophan permease, Tat2p, that is routed to either the plasma membrane or the vacuole depending on the concentration of tryptophan in the medium.…”

Section: A Second Form Of Autophagic Degradation Of the Yeast Nucleusmentioning

confidence: 99%

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The intricacy of nuclear membrane dynamics during nucleophagy

Mijaljica

Prescott

Devenish

2010

Nucleus

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The nucleus is a site of a number of essential metabolic activities relating to maintenance and expression of the genome. Such activities include: DNA replication, recombination and repair, gene transcription, RNA processing and ribosome subunit maturation and assembly. 1,2 In order for these essential activities to be carried out in a correct and efficient manner the corresponding machinery must be maintained. Consequently, it is to be expected there are processes within cells which act to 'repair' nuclear damage through the coordinated removal of damaged non-functional components, or those surplus to requirement. A growing body of evidence indicates that parts of the nucleus can be specifically degraded by nucleophagy (micronucleophagy), an autophagic process involving localized changes in membrane organization and dynamics. Here, we discuss nucleophagy in this context as well as its role in 'housecleaning' during nutrient Nuclear Structure, Function and CompartmentalizationThe nucleus is not only the largest membrane-enclosed organelle in eukaryotic cells, but arguably the most elaborate. Two main structures make up the metazoan (including mammalian) nucleus. The first of these is the nuclear envelope (NE) that acts as the interface between the nucleus and the rest of the cell enclosing the contents of the nucleus. 3,4 The second is the nuclear lamina, a dense but fenestrated network composed of intermediate filaments made of lamins and lamin-associated (e.g., emerin) proteins underlying the inner surface of the NE. The NE is required for maintenance of nuclear shape, spacing of nuclear pore complexes (NPCs), organization of heterochromatin, DNA replication and regulation of transcription factors (Fig. 1). [5][6][7][8][9][10][11] Certain organisms, such as fungi or plants lack lamins 12 and consequently lack a nuclear lamina. 13 Plants contain coiled-coil proteins, apparently unrelated to lamins, which serve as nucleoskeleton components.12,14,15 Coiled-coil proteins have been implicated also as nucleoskeleton components in non-metazoans, notably yeast and Trypanosoma brucei. 12,16,17 The NE is comprised of two concentric, closely opposed lipid bilayers, the outer and inner nuclear membranes (ONM and INM, respectively). 4,18 The ONM is continuous with the rough endoplasmic reticulum (rER), studded with ribosomes and functions in secretion and lipid biosynthesis. The ribosome-free INM faces the viscous nucleoplasm, and contains a unique spectrum of integral and membrane-associated proteins that provide binding sites for the nuclear lamina and chromatin. The ONM and INM are separated by a luminal space but become contiguous at sites of high membrane curvature occupied by the NPCs (Fig. 1). NPCs exclusively mediate and regulate nucleocytoplasmic trafficking, the signal-dependent, bidirectional trafficking of macromolecules between the nucleus and cytoplasm which is crucial for both gene expression and chromosomal maintenance. 7,[18][19][20] The interior of the nucleus lacks membrane-bound subcompartments, but is...

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Nuclear envelope‐remodeling events as models to assess the potential role of membranes on genome stability

Bâcle,

Groizard,

Kumanski

et al. 2023

FEBS Letters

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The nuclear envelope (NE) encloses the genetic material and functions in chromatin organization and stability. In Saccharomyces cerevisiae, the NE is bound to the ribosomal DNA (rDNA), highly repeated and transcribed, thus prone to genetic instability. While tethering limits instability, it simultaneously triggers notable NE remodeling. We posit here that NE remodeling may contribute to genome integrity maintenance. The NE importance in genome expression, structure, and integrity is well recognized, yet studies mostly focus on peripheral proteins and nuclear pores, not on the membrane itself. We recently characterized a NE invagination drastically obliterating the rDNA, which we propose here as a model to probe if and how membranes play an active role in genome stability preservation.

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Nucleus–vacuole junctions in yeast: anatomy of a membrane contact site

Cited by 45 publications

References 19 publications

Nucleophagy at a glance

Nucleophagy at a glance

The intricacy of nuclear membrane dynamics during nucleophagy

Nuclear envelope‐remodeling events as models to assess the potential role of membranes on genome stability

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