scholarly journals Lamin-dependent Localization of UNC-84, A Protein Required for Nuclear Migration in Caenorhabditis elegans

2002 ◽  
Vol 13 (3) ◽  
pp. 892-901 ◽  
Author(s):  
Kenneth K. Lee ◽  
Daniel Starr ◽  
Merav Cohen ◽  
Jun Liu ◽  
Min Han ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Periphery ◽  
Nuclear Migration ◽  
Cell Stage ◽  
Inner Nuclear Membrane ◽  
Late Anaphase

Mutations in the Caenorhabditis elegans unc-84 gene cause defects in nuclear migration and anchoring. We show that endogenous UNC-84 protein colocalizes with Ce-lamin at the nuclear envelope and that the envelope localization of UNC-84 requires Ce-lamin. We also show that during mitosis, UNC-84 remains at the nuclear periphery until late anaphase, similar to known inner nuclear membrane proteins. UNC-84 protein is first detected at the 26-cell stage and thereafter is present in most cells during development and in adults. UNC-84 is properly expressed in unc-83 andanc-1 lines, which have phenotypes similar tounc-84, suggesting that neither the expression nor nuclear envelope localization of UNC-84 depends on UNC-83 or ANC-1 proteins. The envelope localization of Ce-lamin, Ce-emerin, Ce-MAN1, and nucleoporins are unaffected by the loss of UNC-84. UNC-84 is not required for centrosome attachment to the nucleus because centrosomes are localized normally in unc-84 hyp7 cells despite a nuclear migration defect. Models for UNC-84 localization are discussed.

scholarly journals SUN-1 and ZYG-12, Mediators of Centrosome–Nucleus Attachment, Are a Functional SUN/KASH Pair in Caenorhabditis elegans

2009 ◽  
Vol 20 (21) ◽  
pp. 4586-4595 ◽  
Author(s):  
IL Minn ◽  
Melissa M. Rolls ◽  
Wendy Hanna-Rose ◽  
Christian J. Malone
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Coiled Coil ◽  
Physical Interaction ◽  
Type Ii ◽  
Inner Nuclear Membrane ◽  
Sequence Elements ◽  
Inner Nuclear Membrane Protein ◽  
Sun Domain

Klarsicht/ANC-1/Syne/homology (KASH)/Sad-1/UNC-84 (SUN) protein pairs can act as connectors between cytoplasmic organelles and the nucleoskeleton. Caenorhabditis elegans ZYG-12 and SUN-1 are essential for centrosome–nucleus attachment. Although SUN-1 has a canonical SUN domain, ZYG-12 has a divergent KASH domain. Here, we establish that the ZYG-12 mini KASH domain is functional and, in combination with a portion of coiled-coil domain, is sufficient for nuclear envelope localization. ZYG-12 and SUN-1 are hypothesized to be outer and inner nuclear membrane proteins, respectively, and to interact, but neither their topologies nor their physical interaction has been directly investigated. We show that ZYG-12 is a type II outer nuclear membrane (ONM) protein and that SUN-1 is a type II inner nuclear membrane protein. The proteins interact in the luminal space of the nuclear envelope via the ZYG-12 mini KASH domain and a region of SUN-1 that does not include the SUN domain. SUN-1 is hypothesized to restrict ZYG-12 to the ONM, preventing diffusion through the endoplasmic reticulum. We establish that ZYG-12 is indeed immobile at the ONM by using fluorescence recovery after photobleaching and show that SUN-1 is sufficient to localize ZYG-12 in cells. This work supports current models of KASH/SUN pairs and highlights the diversity in sequence elements defining KASH domains.

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.

scholarly journals Nuclear envelope proteomics: Novel integral membrane proteins of the inner nuclear membrane

2001 ◽  
Vol 98 (21) ◽  
pp. 11943-11948 ◽  
Author(s):  
M. Dreger ◽  
L. Bengtsson ◽  
T. Schoneberg ◽  
H. Otto ◽  
F. Hucho
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Integral Membrane Proteins ◽  
Inner Nuclear Membrane

The Nuclear Envelope and Human Disease

Physiology ◽  
2004 ◽  
Vol 19 (5) ◽  
pp. 309-314 ◽  
Author(s):  
Antoine Muchir ◽  
Howard J. Worman
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Intermediate Filament ◽  
Human Disease ◽  
Aging Process ◽  
Intermediate Filament Proteins ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamins ◽  
Nuclear Lamin

Mutations in nuclear lamins A and C, intermediate filament proteins of the nuclear envelope, cause diseases affecting various tissues and the aging process. We review what is known about nuclear lamin function and the different diseases caused by mutations in lamins A and C and associated inner nuclear membrane proteins.

scholarly journals The inner nuclear membrane proteins Man1 and Ima1 link to two different types of chromatin at the nuclear periphery inS. pombe

Nucleus ◽  
2012 ◽  
Vol 3 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Babett Steglich ◽  
Guillaume Filion ◽  
Bas van Steensel ◽  
Karl Ekwall
Keyword(s):  
Membrane Proteins ◽  
Nuclear Membrane ◽  
Nuclear Periphery ◽  
Inner Nuclear Membrane ◽  
Different Types

scholarly journals The Caenorhabditis elegans SUN protein UNC-84 interacts with lamin to transfer forces from the cytoplasm to the nucleoskeleton during nuclear migration

2014 ◽  
Vol 25 (18) ◽  
pp. 2853-2865 ◽  
Author(s):  
Courtney R. Bone ◽  
Erin C. Tapley ◽  
Mátyás Gorjánácz ◽  
Daniel A. Starr
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Missense Mutation ◽  
Nuclear Membrane ◽  
Nuclear Migration ◽  
Live Imaging ◽  
Mechanical Forces ◽  
The Sun ◽  
Critical Component ◽  
Linc Complex

Nuclear migration is a critical component of many cellular and developmental processes. The nuclear envelope forms a barrier between the cytoplasm, where mechanical forces are generated, and the nucleoskeleton. The LINC complex consists of KASH proteins in the outer nuclear membrane and SUN proteins in the inner nuclear membrane that bridge the nuclear envelope. How forces are transferred from the LINC complex to the nucleoskeleton is poorly understood. The Caenorhabditis elegans lamin, LMN-1, is required for nuclear migration and interacts with the nucleoplasmic domain of the SUN protein UNC-84. This interaction is weakened by the unc-84(P91S) missense mutation. These mutant nuclei have an intermediate nuclear migration defect—live imaging of nuclei or LMN-1::GFP shows that many nuclei migrate normally, others initiate migration before subsequently failing, and others fail to begin migration. At least one other component of the nucleoskeleton, the NET5/Samp1/Ima1 homologue SAMP-1, plays a role in nuclear migration. We propose a nut-and-bolt model to explain how forces are dissipated across the nuclear envelope during nuclear migration. In this model, SUN/KASH bridges serve as bolts through the nuclear envelope, and nucleoskeleton components LMN-1 and SAMP-1 act as both nuts and washers on the inside of the nucleus.

scholarly journals System analysis shows distinct mechanisms and common principles of nuclear envelope protein dynamics

2011 ◽  
Vol 193 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Nikolaj Zuleger ◽  
David A. Kelly ◽  
A. Christine Richardson ◽  
Alastair R. W. Kerr ◽  
Martin W. Goldberg ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
System Analysis ◽  
Nuclear Pore ◽  
Binding Affinities ◽  
Inner Nuclear Membrane ◽  
Wide Range ◽  
Recovery Times

The nuclear envelope contains >100 transmembrane proteins that continuously exchange with the endoplasmic reticulum and move within the nuclear membranes. To better understand the organization and dynamics of this system, we compared the trafficking of 15 integral nuclear envelope proteins using FRAP. A surprising 30-fold range of mobilities was observed. The dynamic behavior of several of these proteins was also analyzed after depletion of ATP and/or Ran, two functions implicated in endoplasmic reticulum–inner nuclear membrane translocation. This revealed that ATP- and Ran-dependent translocation mechanisms are distinct and not used by all inner nuclear membrane proteins. The Ran-dependent mechanism requires the phenylalanine-glycine (FG)-nucleoporin Nup35, which is consistent with use of the nuclear pore complex peripheral channels. Intriguingly, the addition of FGs to membrane proteins reduces FRAP recovery times, and this also depends on Nup35. Modeling of three proteins that were unaffected by either ATP or Ran depletion indicates that the wide range in mobilities could be explained by differences in binding affinities in the inner nuclear membrane.

scholarly journals Evolvement of LEM proteins as chromatin tethers at the nuclear periphery

2011 ◽  
Vol 39 (6) ◽  
pp. 1735-1741 ◽  
Author(s):  
Andreas Brachner ◽  
Roland Foisner
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Periphery ◽  
Transmembrane Proteins ◽  
Signal Transducer ◽  
Protein Inhibitor ◽  
Inner Nuclear Membrane ◽  
Unicellular Eukaryotes ◽  
Attachment Factor ◽  
Affect Gene Expression

The nuclear envelope in eukaryotic cells has important roles in chromatin organization. The inner nuclear membrane contains over 60 transmembrane proteins. LEM [LAP2 (lamina-associated polypeptide 2)/emerin/MAN1] domain-containing proteins of the inner nuclear membrane are involved in tethering chromatin to the nuclear envelope and affect gene expression. They contain a common structural, bihelical motif, the so-called LEM domain, which mediates binding to a conserved chromatin protein, BAF (barrier to autointegration factor). Interestingly, this domain is highly related to other bihelical motifs, termed HeH (helix–extension–helix) and SAP {SAF (scaffold attachment factor)/acinus/PIAS [protein inhibitor of activated STAT (signal transducer and activator of transcription)]} motifs, which are directly linked to DNA. In the present paper, we summarize evidence that the LEM motif evolved from the HeH and SAP domains concomitantly with BAF. In addition, we discuss the potential evolution of HeH/SAP and LEM domain-containing proteins and their role in chromatin tethering and gene regulation from unicellular eukaryotes to mammals.

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