nucleoskeleton

The nucleoskeleton is a network of filamentous proteins inside the cell nucleus that provides mechanical support, helps maintain nuclear shape, and contributes to the organization and regulation of chromatin. It is distinct from the cytoskeleton but interacts with it through the nuclear envelope. The nucleoskeleton includes the nuclear lamina, nuclear actin and actin-related networks, and other scaffolding proteins that share links to chromatin and the nuclear envelope.

A central element is the nuclear lamina, a dense mesh underlying the inner nuclear membrane composed mainly of lamins A/C and B-type lamins, together with lamin-associated proteins such as emerin, LAP2, and LBR. The LINC complex, formed by SUN proteins in the inner membrane and Nesprins in the outer membrane, connects the nucleoskeleton to cytoskeletal networks. Nuclear actin and related factors also participate in chromatin remodeling and transcription within the nucleus.

Functionally, the nucleoskeleton provides structural resilience to mechanical stress, maintains nuclear morphology, and constrains or guides chromatin organization. It anchors heterochromatin to the lamina, contributes to the formation of lamina-associated domains, and participates in DNA repair and gene regulation. Its organization is dynamic, changing during development, differentiation, and in response to mechanical cues.

Clinical and research relevance: Alterations in lamins or lamin-associated proteins underlie several diseases, including muscular dystrophy, cardiomyopathy, lipodystrophy, and premature aging syndromes such as Hutchinson-Gilford progeria. Studies of the nucleoskeleton illuminate how nuclear mechanics influence cell migration, genome stability, and transcriptional programs.