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

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

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 mediate 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 exposure across the nuclear membrane. 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 its absence.