unc-83encodes a novel component of the nuclear envelope and is essential for proper nuclear migration

Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 5039-5050 ◽  
Author(s):  
Daniel A. Starr ◽  
Greg J. Hermann ◽  
Christian J. Malone ◽  
William Fixsen ◽  
James R. Priess ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Essential Role ◽  
Transmembrane Protein ◽  
Nuclear Lamina ◽  
Nuclear Migration ◽  
C Elegans ◽  
Specific Manner ◽  
Sun Domain ◽  
P Cells

Nuclear migration plays an essential role in the growth and development of a wide variety of eukaryotes. Mutations in unc-84, which encodes a conserved component of the nuclear envelope, have been shown to disrupt nuclear migration in two C. elegans tissues. We show that mutations in unc-83 disrupt nuclear migration in a similar manner in migrating P cells, hyp7 precursors and the intestinal primordium, but have no obvious defects in the association of centrosomes with nuclei or the structure of the nuclear lamina of migrating nuclei. We also show that unc-83 encodes a novel transmembrane protein. We identified three unc-83 transcripts that are expressed in a tissue-specific manner. Antibodies against UNC-83 co-localized to the nuclear envelope with lamin and UNC-84. Unlike UNC-84, UNC-83 localized to only specific nuclei, many of which were migratory. UNC-83 failed to localize to the nuclear envelope in unc-84 mutants with lesions in the conserved SUN domain of UNC-84, and UNC-83 interacted with the SUN domain of UNC-84 in vitro, suggesting that these two proteins function together during nuclear migration. We favor a model in which UNC-84 directly recruits UNC-83 to the nuclear envelope where they help transfer force between the cytoskeleton and the nucleus.

Cellular Samurai: katanin and the severing of microtubules

2000 ◽  
Vol 113 (16) ◽  
pp. 2821-2827 ◽  
Author(s):  
L. Quarmby
Keyword(s):  
Epithelial Cells ◽  
Essential Role ◽  
Aaa Atpase ◽  
C Elegans ◽  
Microtubule Severing ◽  
Biochemical Studies ◽  
New Evidence

Recent biochemical studies of the AAA ATPase, katanin, provide a foundation for understanding how microtubules might be severed along their length. These in vitro studies are complemented by a series of recent reports of direct in vivo observation of microtubule breakage, which indicate that the in vitro phenomenon of catalysed microtubule severing is likely to be physiological. There is also new evidence that microtubule severing by katanin is important for the production of non-centrosomal microtubules in cells such as neurons and epithelial cells. Although it has been difficult to establish the role of katanin in mitosis, new genetic evidence indicates that a katanin-like protein, MEI-1, plays an essential role in meiosis in C. elegans. Finally, new proteins involved in the severing of axonemal microtubules have been discovered in the deflagellation system of Chlamydomonas.

scholarly journals Supramolecular Structures of the Dictyostelium Lamin NE81

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 162
Author(s):  
Marianne Grafe ◽  
Petros Batsios ◽  
Irene Meyer ◽  
Daria Lisin ◽  
Otto Baumann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Model Organism ◽  
Super Resolution ◽  
Nuclear Lamina ◽  
Stimulated Emission ◽  
Structural Level ◽  
Animal Cells ◽  
Nuclear Lamins

Nuclear lamins are nucleus-specific intermediate filaments (IF) found at the inner nuclear membrane (INM) of the nuclear envelope (NE). Together with nuclear envelope transmembrane proteins, they form the nuclear lamina and are crucial for gene regulation and mechanical robustness of the nucleus and the whole cell. Recently, we characterized Dictyostelium NE81 as an evolutionarily conserved lamin-like protein, both on the sequence and functional level. Here, we show on the structural level that the Dictyostelium NE81 is also capable of assembling into filaments, just as metazoan lamin filament assemblies. Using field-emission scanning electron microscopy, we show that NE81 expressed in Xenopous oocytes forms filamentous structures with an overall appearance highly reminiscent of Xenopus lamin B2. The in vitro assembly properties of recombinant His-tagged NE81 purified from Dictyostelium extracts are very similar to those of metazoan lamins. Super-resolution stimulated emission depletion (STED) and expansion microscopy (ExM), as well as transmission electron microscopy of negatively stained purified NE81, demonstrated its capability of forming filamentous structures under low-ionic-strength conditions. These results recommend Dictyostelium as a non-mammalian model organism with a well-characterized nuclear envelope involving all relevant protein components known in animal cells.

scholarly journals A laminopathic mutation disrupting lamin filament assembly causes disease-like phenotypes in Caenorhabditis elegans

2011 ◽  
Vol 22 (15) ◽  
pp. 2716-2728 ◽  
Author(s):  
Erin M. Bank ◽  
Kfir Ben-Harush ◽  
Naama Wiesel-Motiuk ◽  
Rachel Barkan ◽  
Naomi Feinstein ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Fluorescent Protein ◽  
Electron Tomography ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
C Elegans ◽  
Filament Assembly ◽  
Filament Structure ◽  
Green Fluorescent

Mutations in the human LMNA gene underlie many laminopathic diseases, including Emery-Dreifuss muscular dystrophy (EDMD); however, a mechanistic link between the effect of mutations on lamin filament assembly and disease phenotypes has not been established. We studied the ΔK46 Caenorhabditis elegans lamin mutant, corresponding to EDMD-linked ΔK32 in human lamins A and C. Cryo-electron tomography of lamin ΔK46 filaments in vitro revealed alterations in the lateral assembly of dimeric head-to-tail polymers, which causes abnormal organization of tetrameric protofilaments. Green fluorescent protein (GFP):ΔK46 lamin expressed in C. elegans was found in nuclear aggregates in postembryonic stages along with LEM-2. GFP:ΔK46 also caused mislocalization of emerin away from the nuclear periphery, consistent with a decreased ability of purified emerin to associate with lamin ΔK46 filaments in vitro. GFP:ΔK46 animals had motility defects and muscle structure abnormalities. These results show that changes in lamin filament structure can translate into disease-like phenotypes via altering the localization of nuclear lamina proteins, and suggest a model for how the ΔK32 lamin mutation may cause EDMD in humans.

scholarly journals DrosophilaklaroidEncodes a SUN Domain Protein Required for Klarsicht Localization to the Nuclear Envelope and Nuclear Migration in the Eye

Fly ◽  
2007 ◽  
Vol 1 (2) ◽  
pp. 75-85 ◽  
Author(s):  
Martin P. Kracklauer ◽  
Susan M.L. Banks ◽  
Xuanhua Xie ◽  
Yaning Wu ◽  
Janice A. Fischer
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Migration ◽  
Domain Protein ◽  
Sun Domain

scholarly journals Cytomegaloviral proteins that associate with the nuclear lamina: components of a postulated nuclear egress complex

2009 ◽  
Vol 90 (3) ◽  
pp. 579-590 ◽  
Author(s):  
Jens Milbradt ◽  
Sabrina Auerochs ◽  
Heinrich Sticht ◽  
Manfred Marschall
Keyword(s):  
Nuclear Envelope ◽  
Transmembrane Protein ◽  
Nuclear Lamina ◽  
Cellular Proteins ◽  
Lamin B ◽  
Nuclear Egress ◽  
Lamin B Receptor ◽  
Individual Interaction ◽  
Sequence Elements ◽  
Protein Recruitment

The nuclear egress of cytomegaloviral capsids traversing the nuclear envelope is dependent on a locally restricted destabilization of the rigid nuclear lamina. It has been suggested that the multi-component nuclear egress complex (NEC) that is formed is comprised of both viral and cellular proteins which act to recruit lamin-phosphorylating protein kinases. Recently, we reported that the lamina-associated human cytomegalovirus-encoded proteins pUL50 and pUL53, conserved among herpesviruses, interact with each other and recruit protein kinase C (PKC) to the nuclear envelope in transfected cells. The multiple interactions of the transmembrane protein pUL50 with pUL53, PKC and cellular PKC-binding protein p32, appear crucial to the formation of the NEC. In this study, we mapped individual interaction sequence elements of pUL50 by coimmunoprecipitation analysis of deletion mutants and yeast two-hybrid studies. Amino acids 1–250 were shown to be responsible for interaction with pUL53, 100–280 for PKC and 100–358 for p32. Interestingly, p32 specifically interacted with multiple NEC components, including the kinases PKC and pUL97, thus possibly acting as an adaptor for protein recruitment to the lamin B receptor. Notably, p32 was the only protein that interacted with the lamin B receptor. Immunofluorescence studies visualized the colocalization of NEC components at the nuclear rim in coexpression studies. The data imply that a tight interaction between at least six viral and cellular proteins leads to the formation of a postulated multi-protein complex required for nuclear egress.

scholarly journals A role for Rab5 in structuring the endoplasmic reticulum

2007 ◽  
Vol 178 (1) ◽  
pp. 43-56 ◽  
Author(s):  
Anjon Audhya ◽  
Arshad Desai ◽  
Karen Oegema
Keyword(s):  
Endoplasmic Reticulum ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Rab Gtpases ◽  
C Elegans ◽  
Rab Family ◽  
Kinetics Of

The endoplasmic reticulum (ER) is a contiguous network of interconnected membrane sheets and tubules. The ER is differentiated into distinct domains, including the peripheral ER and nuclear envelope. Inhibition of two ER proteins, Rtn4a and DP1/NogoA, was previously shown to inhibit the formation of ER tubules in vitro. We show that the formation of ER tubules in vitro also requires a Rab family GTPase. Characterization of the 29 Caenorhabditis elegans Rab GTPases reveals that depletion of RAB-5 phenocopies the defects in peripheral ER structure that result from depletion of RET-1 and YOP-1, the C. elegans homologues of Rtn4a and DP1/NogoA. Perturbation of endocytosis by other means did not affect ER structure; the role of RAB-5 in ER morphology is thus independent of its well-studied requirement for endocytosis. RAB-5 and YOP-1/RET-1 also control the kinetics of nuclear envelope disassembly, which suggests an important role for the morphology of the peripheral ER in this process.

scholarly journals Decreased torsinA or LINC Complex Function Rescues a Laminopathy in Caenorhabditis elegans

2020 ◽  
Author(s):  
Gabriela Huelgas-Morales ◽  
Mark Sanders ◽  
Gemechu Mekonnen ◽  
Tatsuya Tsukamoto ◽  
David Greenstein
Keyword(s):  
Nuclear Envelope ◽  
Complex Function ◽  
Nuclear Lamina ◽  
Premature Aging ◽  
Linc Complex ◽  
Force Transmission ◽  
Complex Activity ◽  
Aaa Atpase ◽  
C Elegans ◽  
Associated Proteins

AbstractThe function of the nucleus depends on the integrity of the nuclear lamina, an intermediate filament network associated with the linker of nucleoskeleton and cytoskeleton (LINC) complex spanning the nuclear envelope. In turn, the AAA+ ATPase torsinA regulates force transmission from the cytoskeleton to the nucleus. In humans, mutations affecting nuclear envelope-associated proteins cause laminopathies, including progeria, myopathy, and dystonia. We report that decreasing the function of the C. elegans torsinA homolog, OOC-5, rescues the sterility and premature aging caused by a null mutation in the single worm lamin homolog, lmn-1. Loss of OOC-5 activity prevents nuclear collapse in lmn-1 mutants by disrupting the function of the LINC complex. These results suggest that LINC complex-transmitted forces damage nuclei with a compromised nuclear lamina.One Sentence SummaryInhibiting LINC complex activity prevents a progeric syndrome in C. elegans.

scholarly journals spe-43 is required for sperm activation in C. elegans

2017 ◽  
Author(s):  
Amber R. Krauchunas ◽  
Ernesto Mendez ◽  
Julie Zhouli Ni ◽  
Marina Druzhinina ◽  
Amanda Mulia ◽  
...  
Keyword(s):  
Transmembrane Protein ◽  
Activation Process ◽  
Deletion Mapping ◽  
Cell Periphery ◽  
Wild Type ◽  
Sperm Activation ◽  
C Elegans ◽  
Phenotypic And Genetic Characterization

ABSTRACTSuccessful fertilization requires that sperm are activated prior to contacting an oocyte. In C. elegans, this activation process, called spermiogenesis, transforms round immobile spermatids into motile, fertilization-competent spermatozoa. We describe the phenotypic and genetic characterization of spe-43, a new component of the spe-8 pathway, which is required for spermiogenesis in hermaphrodites; spe-43 hermaphrodites are self-sterile, while spe-43 males show wild-type fertility. When exposed to Pronase to activate sperm in vitro, spe-43 spermatids form long rigid spikes radiating outward from the cell periphery instead of forming a motile pseudopod, indicating that spermiogenesis initiates but is not completed. Using a combination of recombinant and deletion mapping and whole genome sequencing, we identified F09E8.1 as spe-43. SPE-43 is predicted to exist in two isoforms; one isoform appears to be a single-pass transmembrane protein while the other is predicted to be a secreted protein. SPE-43 can bind to other known sperm proteins, including SPE-4 and SPE-29, which are known to impact spermiogenesis. In summary, we have identified a membrane protein that is present in C. elegans sperm and is required for sperm activation via the hermaphrodite activation signal.

scholarly journals Decreased mechanotransduction prevents nuclear collapse in aCaenorhabditis eleganslaminopathy

2020 ◽  
Vol 117 (49) ◽  
pp. 31301-31308
Author(s):  
Gabriela Huelgas-Morales ◽  
Mark Sanders ◽  
Gemechu Mekonnen ◽  
Tatsuya Tsukamoto ◽  
David Greenstein
Keyword(s):  
Nuclear Envelope ◽  
Complex Function ◽  
Nuclear Lamina ◽  
Premature Aging ◽  
Nuclear Pore ◽  
Linc Complex ◽  
Force Transmission ◽  
Cell Nuclei ◽  
Aaa Atpase ◽  
C Elegans

The function of the nucleus depends on the integrity of the nuclear lamina, an intermediate filament network associated with the linker of nucleoskeleton and cytoskeleton (LINC) complex. The LINC complex spans the nuclear envelope and mediates nuclear mechanotransduction, the process by which mechanical signals and forces are transmitted across the nuclear envelope. In turn, the AAA+ ATPase torsinA is thought to regulate force transmission from the cytoskeleton to the nucleus. In humans, mutations affecting nuclear envelope-associated proteins cause laminopathies, including progeria, myopathy, and dystonia, though the extent to which endogenous mechanical stresses contribute to these pathologies is unclear. Here, we use theCaenorhabditis elegansgermline as a model to investigate mechanisms that maintain nuclear integrity as germ cell nuclei progress through meiotic development and migrate for gametogenesis—processes that require LINC complex function. We report that decreasing the function of theC. eleganstorsinA homolog, OOC-5, rescues the sterility and premature aging caused by a null mutation in the single worm lamin homolog. We show that decreasing OOC-5/torsinA activity prevents nuclear collapse in lamin mutants by disrupting the function of the LINC complex. At a mechanistic level, OOC-5/torsinA promotes the assembly or maintenance of the lamin-associated LINC complex and this activity is also important for interphase nuclear pore complex insertion into growing germline nuclei. These results demonstrate that LINC complex-transmitted forces damage nuclei with a compromised nuclear lamina. Thus, the torsinA–LINC complex nexus might comprise a therapeutic target for certain laminopathies by preventing damage from endogenous cellular forces.

scholarly journals A network of nuclear envelope proteins and cytoskeletal force generators mediates movements of and within nuclei throughout Caenorhabditis elegans development

2019 ◽  
Vol 244 (15) ◽  
pp. 1323-1332 ◽  
Author(s):  
Daniel A Starr
Keyword(s):  
Dna Damage ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Dna Damage Repair ◽  
Nuclear Migration ◽  
Envelope Proteins ◽  
Nuclear Positioning ◽  
C Elegans ◽  
Damage Repair

Nuclear migration and anchorage, together referred to as nuclear positioning, are central to many cellular and developmental events. Nuclear positioning is mediated by a conserved network of nuclear envelope proteins that interacts with force generators in the cytoskeleton. At the heart of this network are linker of nucleoskeleton and cytoskeleton (LINC) complexes made of Sad1 and UNC-84 (SUN) proteins at the inner nuclear membrane and Klarsicht, ANC-1, and Syne homology (KASH) proteins in the outer nuclear membrane. LINC complexes span the nuclear envelope, maintain nuclear envelope architecture, designate the surface of nuclei distinctly from the contiguous endoplasmic reticulum, and were instrumental in the early evolution of eukaryotes. LINC complexes interact with lamins in the nucleus and with various cytoplasmic KASH effectors from the surface of nuclei. These effectors regulate the cytoskeleton, leading to a variety of cellular outputs including pronuclear migration, nuclear migration through constricted spaces, nuclear anchorage, centrosome attachment to nuclei, meiotic chromosome movements, and DNA damage repair. How LINC complexes are regulated and how they function are reviewed here. The focus is on recent studies elucidating the best-understood network of LINC complexes, those used throughout Caenorhabditis elegans development. Impact statement Defects in nuclear positioning disrupt development in many mammalian tissues. In human development, LINC complexes play important cellular functions including nuclear positioning, homolog pairing in meiosis, DNA damage repair, wound healing, and gonadogenesis. The topics reviewed here are relevant to public health because defects in nuclear positioning and mutations in LINC components are associated with a wide variety of human diseases including muscular dystrophies, neurological disorders, progeria, aneurysms, hearing loss, blindness, sterility, and multiple cancers. Although this review focuses on findings in the model nematode Caenorhabditis elegans, the studies are relevant because almost all the findings originally made in C. elegans are conserved to humans. Furthermore, C. elegans remains the best described network for how LINC complexes are regulated and function.

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