Here come the SUNs: a nucleocytoskeletal missing link.

The nuclear envelope has traditionally been thought of as a barrier that separates the nucleoplasm from the cytoplasm in eukaryotic cells. Increasing evidence shows that the nuclear envelope also links the inside of the nucleus to the cytoskeleton. Here we discuss recent papers showing that this link occurs through complexes of lamins on the inner aspect of the inner nuclear membrane, transmembrane proteins of the inner nuclear membrane called SUNs and large nesprin isoforms localized specifically to the outer nuclear membrane. These discoveries have implications for nuclear positioning, nuclear migration and pathogenesis of inherited diseases that are caused by mutations in nuclear envelope proteins.