Fig. 1: Disassembly and localization of lamins during the nuclear envelope breakdown.
From: Mitotic dynamics of the nuclear lamina behind the scenes of chromosome separation
Before mitotic entry (from G1 to late G2), lamins are mostly organized into separated A-type (purple) and B-type (red) filament networks that lie beneath the inner nuclear membrane, and form the so-called lamina (although a fraction of lamins is also present as a soluble nucleoplasmic pool). During the nuclear envelope breakdown (NEBD), lamina dismantlement relies on: 1) microtubules (orange lines) driven forces (black arrows) acting on the nuclear envelope (NE), creating stretching forces (black arrows) at the distal site of microtubule polymerization. This ultimately results in the rupture of the NE under these forces; 2) the phosphorylations of A- and B-type lamins by the kinases CDK1 and PKC (and Src for lamin A), on both sides of their rod domain, abolish their assembly into nucleofilaments. The main mitotic phosphorylation events are indicated in the boxes, and summarized in Table 1. Once the NE is disassembled, lamins localize homogeneously in the nucleoplasm, with a higher concentration of B-type lamin close to the centrosomes, at the mitotic spindle pole. Figure created with BioRender.com.
