Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

ER network formation requires a balance of the dynamin-like GTPase Sey1p and the Lunapark family member Lnp1p.

ABSTRACT: Although studies on endoplasmic reticulum (ER) structure and dynamics have focused on the ER tubule-forming proteins (reticulons and DP1/Yop1p) and the tubule fusion protein atlastin, nothing is known about the proteins and processes that act to counterbalance this machinery. Here we show that Lnp1p, a member of the conserved Lunapark family, plays a role in ER network formation. Lnp1p binds to the reticulons and Yop1p and resides at ER tubule junctions in both yeast and mammalian cells. In the yeast Saccharomyces cerevisiae, the interaction of Lnp1p with the reticulon protein, Rtn1p, and the localization of Lnp1p to ER junctions are regulated by Sey1p, the yeast orthologue of atlastin. We propose that Lnp1p and Sey1p act antagonistically to balance polygonal network formation. In support of this proposal, we show that the collapsed, densely reticulated ER network in lnp1 ? cells is partially restored when the GTPase activity of Sey1p is abrogated.

SUBMITTER: Chen S

PROVIDER: S-EPMC3389217 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

ER network formation requires a balance of the dynamin-like GTPase Sey1p and the Lunapark family member Lnp1p.

Chen Shuliang S Novick Peter P Ferro-Novick Susan S

Nature cell biology 20120624 7

Although studies on endoplasmic reticulum (ER) structure and dynamics have focused on the ER tubule-forming proteins (reticulons and DP1/Yop1p) and the tubule fusion protein atlastin, nothing is known about the proteins and processes that act to counterbalance this machinery. Here we show that Lnp1p, a member of the conserved Lunapark family, plays a role in ER network formation. Lnp1p binds to the reticulons and Yop1p and resides at ER tubule junctions in both yeast and mammalian cells. In the ...[more]

PMID: 22729086

Similar Datasets

Arabidopsis Lunapark proteins are involved in ER cisternae formation.

Project description:The plant endoplasmic reticulum (ER) is crucial to the maintenance of cellular homeostasis. The ER consists of a dynamic and continuously remodelling network of tubules and cisternae. Several conserved membrane proteins have been implicated in formation and maintenance of the ER network in plants, such as RHD3 and the reticulon proteins. Despite the recent work in mammalian and yeast cells, the detailed molecular mechanisms of ER network organization in plants remain largely unknown. Recently, novel ER network-shaping proteins called Lunapark (LNP) have been identified in yeast and mammalian cells. Here we identify two Arabidopsis LNP homologues and investigate their subcellular localization via confocal microscopy and potential function in shaping the ER network using protein-protein interaction assays and mutant analysis. We show that AtLNP1 overexpression in tobacco leaf epidermal cells mainly labels cisternae in the ER network, whereas AtLNP2 labels the whole ER. Overexpression of LNP proteins results in an increased abundance of ER cisternae and lnp1 and lnp1lnp2 amiRNA lines display a reduction in cisternae and larger polygonal areas. Thus, we hypothesize that AtLNP1 and AtLNP2 are involved in determining the network morphology of the plant ER, possibly by regulating the formation of ER cisternae.

| S-EPMC6055799 | biostudies-literature

Reciprocal regulation between lunapark and atlastin facilitates ER three-way junction formation.

Project description:Three-way junctions are characteristic structures of the tubular endoplasmic reticulum (ER) network. Junctions are formed through atlastin (ATL)-mediated membrane fusion and stabilized by lunapark (Lnp). However, how Lnp is preferentially enriched at three-way junctions remains elusive. Here, we showed that Lnp loses its junction localization when ATLs are deleted. Reintroduction of ATL1 R77A and ATL3, which have been shown to cluster at the junctions, but not wild-type ATL1, relocates Lnp to the junctions. Mutations in the N-myristoylation site or hydrophobic residues in the coiled coil (CC1) of Lnp N-terminus (NT) cause mis-targeting of Lnp. Conversely, deletion of the lunapark motif in the C-terminal zinc finger domain, which affects the homo-oligomerization of Lnp, does not alter its localization. Purified Lnp-NT attaches to the membrane in a myristoylation-dependent manner. The mutation of hydrophobic residues in CC1 does not affect membrane association, but compromises ATL interactions. In addition, Lnp-NT inhibits ATL-mediated vesicle fusion in vitro. These results suggest that CC1 in Lnp-NT contacts junction-enriched ATLs for proper localization; subsequently, further ATL activity is limited by Lnp after the junction is formed. The proposed mechanism ensures coordinated actions of ATL and Lnp in generating and maintaining three-way junctions.

| S-EPMC6588657 | biostudies-literature

ER stress signaling requires RHD3, a functionally conserved ER-shaping GTPase.

Project description:Whether structure and function are correlated features of organelles is a fundamental question in cell biology. Here, we have assessed the ability of Arabidopsis mutants with a defective endoplasmic reticulum (ER) structure to invoke the unfolded protein response (UPR), an essential ER signaling pathway. Through molecular and genetic approaches, we show that loss of the ER-shaping GTPase Root Hair Defective 3 (RHD3) specifically disrupts the UPR by interfering with the mRNA splicing function of the master regulator IRE1. These findings establish a new role for RHD3 in the ER and support specificity of the effects of ER-shaping mutations on ER function.

| S-EPMC4117228 | biostudies-literature

The ER morphology-regulating lunapark protein induces the formation of stacked bilayer discs.

Project description:Lunapark (Lnp) is a conserved membrane protein that localizes to and stabilizes three-way junctions of the tubular ER network. In higher eukaryotes, phosphorylation of Lnp may contribute to the conversion of the ER from tubules to sheets during mitosis. Here, we report on the reconstitution of purified Lnp with phospholipids. Surprisingly, Lnp induces the formation of stacked membrane discs. Each disc is a bicelle, with Lnp sitting in the bilayer facing both directions. The interaction between bicelles is mediated by the cytosolic domains of Lnp, resulting in a constant distance between the discs. A phosphomimetic Lnp mutant shows reduced bicelle stacking. Based on these results, we propose that Lnp tethers ER membranes in vivo in a cell cycle-dependent manner. Lnp appears to be the first membrane protein that induces the formation of stacked bicelles.

| S-EPMC6238531 | biostudies-literature

Lunapark-dependent formation of a virus-induced ER exit site contains multi-tubular ER junctions that promote viral ER-to-cytosol escape.

Project description:Viruses rearrange host membranes to support different entry steps. Polyomavirus simian virus 40 (SV40) reorganizes the endoplasmic reticulum (ER) membrane to generate focus structures that enable virus ER-to-cytosol escape, a decisive infection step. The molecular architecture of the ER exit site that might illuminate why it is ideally suited for membrane penetration is unknown. Here 3D focused ion beam scanning electron microscopy (FIB-SEM) reconstruction reveals that the ER focus structure consists of multi-tubular ER junctions where SV40 preferentially localizes, suggesting that tubular branch points are virus ER-to-cytosol penetration sites. Functional analysis demonstrates that lunapark-an ER membrane protein that typically stabilizes three-way ER junctions-relocates to the ER foci, where it supports focus formation, leading to SV40 ER escape and infection. Our results reveal how a virus repurposes the activity of an ER membrane protein to form a virus-induced ER substructure required for membrane escape and suggest that ER tubular junctions are vulnerable sites exploited by viruses for membrane penetration.

| S-EPMC8759150 | biostudies-literature

Pollen-tube tip growth requires a balance of lateral propagation and global inhibition of Rho-family GTPase activity.

Project description:Rapid tip growth allows for efficient development of highly elongated cells (e.g. neuronal axons, fungal hyphae and pollen tubes) and requires an elaborate spatiotemporal regulation of the growing region. Here, we use the pollen tube as a model to investigate the mechanism regulating the growing region. ROPs (Rho-related GTPases from plants) are essential for pollen tip growth and display oscillatory activity changes in the apical plasma membrane (PM). By manipulating the ROP activity level, we showed that the PM distribution of ROP activity as an apical cap determines the tip growth region and that efficient tip growth requires an optimum level of the apical ROP1 activity. Excessive ROP activation induced the enlargement of the tip growth region, causing growth depolarization and reduced tube elongation. Time-lapse analysis suggests that the apical ROP1 cap is generated by lateral propagation of a localized ROP activity. Subcellular localization and gain- and loss-of-function analyses suggest that RhoGDI- and RhoGAP-mediated global inhibition limits the lateral propagation of apical ROP1 activity. We propose that the balance between the lateral propagation and the global inhibition maintains an optimal apical ROP1 cap and generates the apical ROP1 activity oscillation required for efficient pollen-tube elongation.

| S-EPMC2816183 | biostudies-literature

Structures of the yeast dynamin-like GTPase Sey1p provide insight into homotypic ER fusion.

Project description:Homotypic membrane fusion of the endoplasmic reticulum is mediated by dynamin-like guanosine triphosphatases (GTPases), which include atlastin (ATL) in metazoans and Sey1p in yeast. In this paper, we determined the crystal structures of the cytosolic domain of Sey1p derived from Candida albicans. The structures reveal a stalk-like, helical bundle domain following the GTPase, which represents a previously unidentified configuration of the dynamin superfamily. This domain is significantly longer than that of ATL and critical for fusion. Sey1p forms a side-by-side dimer in complex with GMP-PNP or GDP/AlF4(-) but is monomeric with GDP. Surprisingly, Sey1p could mediate fusion without GTP hydrolysis, even though fusion was much more efficient with GTP. Sey1p was able to replace ATL in mammalian cells, and the punctate localization of Sey1p was dependent on its GTPase activity. Despite the common function of fusogenic GTPases, our results reveal unique features of Sey1p.

| S-EPMC4576867 | biostudies-literature

Neurolastin, a Dynamin Family GTPase, Regulates Excitatory Synapses and Spine Density.

Project description:Membrane trafficking and spinogenesis contribute significantly to changes in synaptic strength during development and in various paradigms of synaptic plasticity. GTPases of the dynamin family are key players regulating membrane trafficking. Here, we identify a brain-specific dynamin family GTPase, neurolastin (RNF112/Znf179), with closest homology to atlastin. We demonstrate that neurolastin has functional GTPase and RING domains, making it a unique protein identified with this multi-enzymatic domain organization. We also show that neurolastin is a peripheral membrane protein that localizes to endosomes and affects endosomal membrane dynamics via its RING domain. In addition, neurolastin knockout mice have fewer dendritic spines, and rescue of the wild-type phenotype requires both the GTPase and RING domains. Furthermore, we find fewer functional synapses and reduced paired pulse facilitation in neurolastin knockout mice. Thus, we identify neurolastin as a dynamin family GTPase that affects endosome size and spine density.

| S-EPMC4567839 | biostudies-literature

The anti-viral dynamin family member MxB participates in mitochondrial integrity.

Project description:The membrane deforming dynamin family members MxA and MxB are large GTPases that convey resistance to a variety of infectious viruses. During viral infection, Mx proteins are known to show markedly increased expression via an interferon-responsive promoter to associate with nuclear pores. In this study we report that MxB is an inner mitochondrial membrane GTPase that plays an important role in the morphology and function of this organelle. Expression of mutant MxB or siRNA knockdown of MxB leads to fragmented mitochondria with disrupted inner membranes that are unable to maintain a proton gradient, while expelling their nucleoid-based genome into the cytoplasm. These findings implicate a dynamin family member in mitochondrial-based changes frequently observed during an interferon-based, anti-viral response.

| S-EPMC7044337 | biostudies-literature

The large GTPase dynamin regulates actin comet formation and movement in living cells.

Project description:The large GTPase dynamin (Dyn2) has been demonstrated by us and others to interact with several different actin-binding proteins. To define how Dyn2 might participate in actin dynamics in livings cells we have expressed green fluorescent protein (GFP)-tagged Dyn2 in cultured cells and observed labeling of comet-like vesicles and macropinosomes. The comet structures progressed with a constant velocity and were reminiscent of actin comets associated with motile vesicles in cells expressing type I phosphatidylinositol phosphate 5-kinases. Based on these observations we sought to determine whether Dyn2 is an integral component of actin comets. Cells expressing type I phosphatidylinositol phosphate 5-kinase and Dyn2-GFP revealed a prominent colocalization of Dyn2 and actin in comet structures. Interestingly, comet formation and motility were normal in cells expressing wild-type Dyn2-GFP but altered markedly in Dyn2 mutant-expressing cells. Dyn2K44A-GFP mutant cells displayed a significant reduction in comet number, length, velocity, and efficiency of movement. In contrast, comets in cells expressing Dyn2DeltaPRD-GFP appeared dark and did not incorporate the mutant Dyn2 protein, indicating that the proline-rich domain (PRD) is required for Dyn2 recruitment. Further, these comets were significantly longer and slower than those in control cells. These findings demonstrate a role for Dyn2 in actin-based vesicle motility.

| S-EPMC117533 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data