Nuclear Envelope Retention of LINC Complexes Is Promoted by SUN-1 Oligomerization in the <i>Caenorhabditis elegans</i> Germ Line

Daryabeigi, Anahita; Woglar, Alexander; Baudrimont, Antoine; Silva, Nicola; Paouneskou, Dimitra; Vesely, Cornelia; Rauter, Manuel; Penkner, Alexandra; Jantsch, Michael F.; Jantsch, Verena

doi:10.1534/genetics.116.188094

Cited by 8 publications

(5 citation statements)

References 66 publications

(107 reference statements)

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“…Finally, we cannot overlook the possibility of different mechanisms of LINC formation and function across organisms. For example, contrary to all published data on human and mouse LINC complexes, Daryabeigi et al (64) recently showed that in Caenorhabditis elegans, the oligomerization of SUN1 is not required for the formation of a functional LINC complex. It would be interesting to see how altered oligomerization states could relate to the diverse functions of these highly conserved SUN domain proteins across organisms (65).…”

Section: Autoinhibition Of the Kash Lid In Sun1mentioning

confidence: 75%

Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope

Jahed

Fadavi

et al. 2018

Biophysical Journal

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The LINC complex is found in a wide variety of organisms and is formed by the transluminal interaction between outer- and inner-nuclear-membrane KASH and SUN proteins, respectively. Most extensively studied are SUN1 and SUN2 proteins, which are widely expressed in mammals. Although SUN1 and SUN2 play functionally redundant roles in several cellular processes, more recent studies have revealed diverse and distinct functions for SUN1. While several recent in vitro structural studies have revealed the molecular details of various fragments of SUN2, no such structural information is available for SUN1. Herein, we conduct a systematic analysis of the molecular relationships between SUN1 and SUN2, highlighting key similarities and differences that could lead to clues into their distinct functions. We use a wide range of computational tools, including multiple sequence alignments, homology modeling, molecular docking, and molecular dynamic simulations, to predict structural differences between SUN1 and SUN2, with the goal of understanding the molecular mechanisms underlying SUN1 oligomerization in the nuclear envelope. Our simulations suggest that the structural model of SUN1 is stable in a trimeric state and that SUN1 trimers can associate through their SUN domains to form lateral complexes. We also ask whether SUN1 could adopt an inactive monomeric conformation as seen in SUN2. Our results imply that the KASH binding domain of SUN1 is also inhibited in monomeric SUN1 but through weaker interactions than in monomeric SUN2.

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Section: Autoinhibition Of the Kash Lid In Sun1mentioning

confidence: 75%

Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope

Jahed

Fadavi

et al. 2018

Biophysical Journal

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“…Using the subcellular localization of UAD-2 and the USTC complex as reporters, we have searched for factors that are engaged in H3K27me3-marked facultative heterochromatin compaction and subnuclear localization. SUN-1 is an inner nuclear membrane adaptor protein and is essential for centrosome localization (67). Our candidate-based RNAi screening identified SUN-1, suggesting that SUN-1 may play key roles in recruiting UAD-2 and the USTC complex or heterochromatin to the inner nuclear membrane to create the proper chromatin environment for piRNA transcription.…”

Section: Discussionmentioning

confidence: 93%

A chromodomain protein mediates heterochromatin-directed piRNA expression

Huang

Cheng

Weng

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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PIWI-interacting RNAs (piRNAs) play significant roles in suppressing transposons, maintaining genome integrity, and defending against viral infections. How piRNA source loci are efficiently transcribed is poorly understood. Here, we show that in Caenorhabditis elegans, transcription of piRNA clusters depends on the chromatin microenvironment and a chromodomain-containing protein, UAD-2. piRNA clusters form distinct focus in germline nuclei. We conducted a forward genetic screening and identified UAD-2 that is required for piRNA focus formation. In the absence of histone 3 lysine 27 methylation or proper chromatin-remodeling status, UAD-2 is depleted from the piRNA focus. UAD-2 recruits the upstream sequence transcription complex (USTC), which binds the Ruby motif to piRNA promoters and promotes piRNA generation. Vice versa, the USTC complex is required for UAD-2 to associate with the piRNA focus. Thus, transcription of heterochromatic small RNA source loci relies on coordinated recruitment of both the readers of histone marks and the core transcriptional machinery to DNA.

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“…Accumulation of ZYG-12 at the ONM requires ZYG-12's KASH domain and SUN-1, which together form a relatively immobile complex in the NE (Minn et al 2009). Moreover, oligomerization of SUN-1 (Figure 15; see also Sosa et al 2012) via its central coiled-coil domains contribute to the retention of SUN-1 in the INM, although SUN-1 lacking the coiled-coil domains still form functional LINC complexes (Daryabeigi et al 2016).…”

Section: Pairing Of Meiotic Chromosomesmentioning

confidence: 99%

Cell Biology of theCaenorhabditis elegansNucleus

Cohen-Fix

Askjaer

2017

Genetics

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Studies on the Caenorhabditis elegans nucleus have provided fascinating insight to the organization and activities of eukaryotic cells. Being the organelle that holds the genetic blueprint of the cell, the nucleus is critical for basically every aspect of cell biology. The stereotypical development of C. elegans from a one cell-stage embryo to a fertile hermaphrodite with 959 somatic nuclei has allowed the identification of mutants with specific alterations in gene expression programs, nuclear morphology, or nuclear positioning. Moreover, the early C. elegans embryo is an excellent model to dissect the mitotic processes of nuclear disassembly and reformation with high spatiotemporal resolution. We review here several features of the C. elegans nucleus, including its composition, structure, and dynamics. We also discuss the spatial organization of chromatin and regulation of gene expression and how this depends on tight control of nucleocytoplasmic transport. Finally, the extensive connections of the nucleus with the cytoskeleton and their implications during development are described. Most processes of the C. elegans nucleus are evolutionarily conserved, highlighting the relevance of this powerful and versatile model organism to human biology.KEYWORDS Caenorhabditis elegans; chromatin; gene expression; lamin; LEM-domain proteins; LINC; P granule; nuclear pore complex; nuclear envelope; nucleocytoplasmic transport; nucleolus; WormBook TABLE OF CONTENTSAbstract 25 C. elegans as a model system to study cell biology of the nucleus 26 Structural components of the nucleus 27

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Nuclear Envelope Retention of LINC Complexes Is Promoted by SUN-1 Oligomerization in the Caenorhabditis elegans Germ Line

Cited by 8 publications

References 66 publications

Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope

Molecular Insights into the Mechanisms of SUN1 Oligomerization in the Nuclear Envelope

A chromodomain protein mediates heterochromatin-directed piRNA expression

Cell Biology of theCaenorhabditis elegansNucleus

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