SUN (Sad1 and UNC-84) and KASH (Klarsicht, ANC-1 and Syne homology) proteins are constituents of the inner and outer nuclear membranes. They interact in the perinuclear space via carboxy-terminal SUN-KASH domains to form the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex thereby bridging the nuclear envelope. LINC complexes sustain numerous biological processes by connecting chromatin with the cytoplasmic force generating machinery. Here we show that the coiled-coil domains of SUN-1 are required for oligomerization and retention of the protein in the nuclear envelope, especially at later stages of female gametogenesis. Consistently, deletion of the coiled coil domain makes SUN-1 sensitive to unilateral force generation across the nuclear membrane. However, absence of this domain does not lead to different expression levels of sun-1 and other known meiotic genes in the mutant compared to wild type. Premature loss of SUN-1 from the nuclear envelope leads to embryonic death due to loss of centrosome-nuclear envelope attachment. However, in contrast to previous notions we can show that the coiled-coil domain is dispensable for functional LINC complex formation, exemplified by successful chromosome sorting and synapsis in meiotic prophase I in their absence. Overall design: A total number five samples were analyzed including two independent wild-type replicates and three independent mutant replicates by PE 50bp RNASeq.
Nuclear Envelope Retention of LINC Complexes Is Promoted by SUN-1 Oligomerization in the Caenorhabditis elegans Germ Line.
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