A-type lamins bind both hetero- and euchromatin, the latter being regulated by lamina-associated polypeptide 2alpha [gene expression]

Lamins are components of the peripheral nuclear lamina and interact with heterochromatic genomic regions, termed lamina-associated domains (LADs). In contrast to lamin B1, lamin A/C also localizes throughout the nucleus, where it associates with the chromatin-binding protein lamina-associated polypeptide (LAP) 2alpha. Here we show lamin A/C also interacts with euchromatin, as determined by chromatin immunoprecipitation analyses of eu- and heterochromatin-enriched samples. By way of contrast, lamin B1 was only found associated with heterochromatin. Euchromatic regions occupied by lamin A/C overlap with those bound by LAP2alpha, the depletion of which shifts binding of lamin A/C towards more heterochromatic regions. These alterations in lamin A/C chromatin interaction affect epigenetic histone marks in euchromatin without significantly affecting gene expression, while loss of lamin A/C in heterochromatic regions increased gene expression. Our data show a novel role of nucleoplasmic lamin A/C and LAP2alpha in regulating euchromatin. Overall design: Examination of LaminA, LaminB and Lap2a DNA binding in Lap2alpha +/+ and Lap2a -/- cells and according changes in Histone modifications and gene expression

4

Gesson K, Rescheneder P, Skoruppa MP, von Haeseler A, Dechat T, Foisner R