Lamins in disease: why do ubiquitously expressed nuclear envelope proteinsgive rise to tissue-specific disease phenotypes?

The nuclear lamina is a filamentous structure composed of lamins that suppo rts the inner nuclear membrane. Several integral membrane proteins includin g emerin, LBR, LAP1 and LAP2 bind to nuclear lamins in vitro and can influe nce lamin function and dynamics in vivo. Results from various studies sugge st that lamins function in DNA replication and nuclear envelope assembly an d determine the size and shape of the nuclear envelope. In addition, lamins also bind chromatin and certain DNA sequences, and might influence chromos ome position. Recent evidence has revealed that mutations in A-type lamins give rise to a range of rare, but dominant, genetic disorders, including Em ery-Dreifuss muscular dystrophy, dilated cardiomyopathy with conduction-sys tem disease and Dunnigan-type familial partial lipodystrophy. An examinatio n of how lamins A/C, emerin and other integral membrane proteins interact a t the INM provides the basis for a novel model for how mutations that promo te disease phenotypes are likely to influence these interactions and theref ore cause cellular pathology through a combination of weakness of the lamin a or altered gene expression.