Dynamics and molecular interactions of linker of nucleoskeleton and cytoskeleton (LINC) complex proteins

Abstract

The linker of nucleoskeleton and cytoskeleton (LINC) complex is situated in the nuclear envelope and forms a connection between the lamina and cytoskeletal elements. Sun1, Sun2 and nesprin-2 are important components of the LINC complex. We expressed these proteins fused to green fluorescent protein in embryonic fibroblasts and studied their diffusional mobilities using fluorescence recovery after photobleaching. We show that they all are more mobile in embryonic fibroblasts from mice lacking A-type lamins than in cells from wild-type mice. Knockdown of Sun2 also increased the mobility of a short, chimeric form of nesprin-2 giant (mini-nesprin-2G), whereas the lack of emerin did not affect the mobility of Sun1, Sun2 or mini-nesprin-2G. Fluorescence resonance energy transfer experiments showed Sun1 to be more closely associated with lamin A than is Sun2. Sun1 and Sun2 had similar affinity for the nesprin-2 KASH domain in plasmon surface resonance (Biacore) experiments. This affinity was ten times higher than that previously reported between nesprin-2 and actin. Deletion of the actin-binding domain had no effect on mini-nesprin-2G mobility. Our data support a model in which A-type lamins and Sun2 anchor nesprin-2 in the outer nuclear membrane, whereas emerin, Sun1 and actin are dispensable for this anchoring.

Lamin A variants that cause striated muscle disease are defective in anchoring transmembrane actin-associated nuclear lines for nuclear movement

“…Lamin A/C interacts with components of the LINC complex (17,19,(31)(32)(33), and it is likely through these interactions that it stabilizes and anchors TAN lines. Given that depletion of SUN2 yielded a similar phenotype on TAN line stability and anchoring, it is likely that lamin A/C interaction with SUN2 is responsible for anchoring the nesprin-2G TAN lines.…”

Blocking farnesylation of the prelamin A variant in Hutchinson-Gilford progeria syndrome alters the distribution of A-type lamins

“…The reaction product was subcloned into the pEGFP-C1 in which the EGFP coding region was replaced by monomeric RFP coding region. 60 The plasmid encoding RFP-lamin A has been described previously. 60 Sequencing of cDNA constructs was performed at the Herbert Irving Comprehensive Cancer Center DNA Sequencing Lab at Columbia University Medical Center.…”

Structural insights into SUN-KASH complexes across the nuclear envelope

“…Only recently have molecular characterization and studies of the functional importance of the nuclear double membrane architecture emerged. For example, the linker of the nucleoskeleton and the cytoskeleton (LINC) complex has been identified as a molecular bridge across the NE for the transduction of signaling and mechanical force [1,2]. LINC complexes primarily consist of proteins containing a SUN (Sad1 and UNC84) domain or a KASH (Klarsicht, ANC-1 and Syne homology) domain, which function as a part of the mechano/signaling cascade from the cellular periphery to the genome.…”

“…Indeed, mounting evidence indicates that www.cell-research.com | Cell Research Wenjia Wang et al 1441 npg LINC complexes function in multiple biological processes, including nuclear migration and repositioning, meiotic telomere tethering and chromatin organization, centrosome migration and attachment, nucleokinesis and cellular rigidity homeostasis [1][2][3]. Recently, LINC complexes have been implicated in the regulation of apoptosis [4,5], the maturation and survival of germlines [6], and in the pathology of human diseases linked to mutations of A-type lamins, such as laminopathies and Emery-Dreifuss muscular dystrophy [7][8][9].…”