Project description:A-type lamins bind both hetero- and euchromatin, the latter being regulated by lamina-associated polypeptide 2alpha [gene expression]
Project description: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. Examination of LaminA, LaminB and Lap2a DNA binding in Lap2alpha +/+ and Lap2a -/- cells and according changes in Histone modifications and gene expression
Project description:Lamins are components of the peripheral nuclear lamina and interact with heterochromatic genomic regions, termed lamina-associated domains (LADs). In contrast to Lamin B11, 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 B11 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. Examination of Lamin A/C, Lamin B1 and Lap2a DNA binding in Lap2alpha +/+ and Lap2a -/- cells and according changes in Histone modifications and gene expression
Project description: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.
Project description:Lamins are components of the peripheral nuclear lamina and interact with heterochromatic genomic regions, termed lamina-associated domains (LADs). In contrast to Lamin B11, 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 B11 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.
Project description:In mammals, the nuclear lamina interacts with hundreds of large genomic regions, termed lamina-associated domains (LADs) that are generally in a transcriptionally repressed state. Lamins form the major structural component of the lamina and have been reported to bind DNA and chromatin. Here we systematically evaluated whether lamins are necessary for the peripheral localization of LADs in murine embryonic stem cells. Surprisingly, removal of essentially all lamins did not have any detectable effect on the genome-wide interaction pattern of chromatin with the inner nuclear membrane. This suggests that other components of the inner nuclear membrane mediate these interactions. 2 samples, each with a biological replicate: wt mESC, B type lamin null (dKO) dKO mESC
Project description:In mammals, the nuclear lamina interacts with hundreds of large genomic regions, termed lamina-associated domains (LADs) that are generally in a transcriptionally repressed state. Lamins form the major structural component of the lamina and have been reported to bind DNA and chromatin. Here we systematically evaluated whether lamins are necessary for the peripheral localization of LADs in murine embryonic stem cells. Surprisingly, removal of essentially all lamins did not have any detectable effect on the genome-wide interaction pattern of chromatin with the inner nuclear membrane. This suggests that other components of the inner nuclear membrane mediate these interactions.
Project description:In mammals, the nuclear lamina interacts with hundreds of large genomic regions, termed lamina-associated domains (LADs) that are generally in a transcriptionally repressed state. Lamins form the major structural component of the lamina and have been reported to bind DNA and chromatin. Here we systematically evaluated whether lamins are necessary for the peripheral localization of LADs in murine embryonic stem cells. Surprisingly, removal of essentially all lamins did not have any detectable effect on the genome-wide interaction pattern of chromatin with the inner nuclear membrane. This suggests that other components of the inner nuclear membrane mediate these interactions.
Project description:A-type lamins form a filamentous meshwork beneath the nuclear membrane that anchors large heterochromatic chromatin domains at the nuclear envelope. They also exist as a more dynamic, non-filamentous pool in the nuclear interior, where they interact with gene-rich euchromatin. Lamin-associated polypeptide 2 alpha (LAP2alpha) binds to and maintains the nucleoplasmic lamin pool, but the functional significance of this interaction is poorly understood. Here we investigate the genome-wide chromatin association of A-type lamins during myogenic differentiation in the presence and absence of LAP2alpha. We find that A-type lamins are significantly reorganized on chromatin upon depletion of LAP2alpha, spreading towards active chromatin and accumulating at regions of active H3K27ac and H3K4me3 histone marks close to the genes whose expression is impaired in the absence of LAP2alpha. This reorganization of A-type lamins on chromatin is accompanied by depletion of the active chromatin mark H3K27ac and a significant delay of myogenic differentiation. Thus, the interplay of lamins and LAP2alpha is crucial for proper positioning of intranuclear lamins on chromatin to allow normal myogenic differentiation. This research was funded in whole or in part by the Austrian Science Fund (FWF) to Roland Foisner: P32512-B/DOI:10.55776/P36503 https://www.doi.org/10.55776/P36503 P36503-B/DOI:10.55776/P32512 https://www.doi.org/10.55776/P32512