title: Transcriptional repression mediated by repositioning of genes to the nuclear lamina.
abstract: Nuclear compartmentalization seems to have an important role in regulating metazoan genes. Although studies on immunoglobulin and other loci have shown a correlation between positioning at the nuclear lamina and gene repression, the functional consequences of this compartmentalization remain untested. We devised an approach for inducible tethering of genes to the inner nuclear membrane (INM), and tested the consequences of such repositioning on gene activity in mouse fibroblasts. Here, using three-dimensional DNA-immunoFISH, we demonstrate repositioning of chromosomal regions to the nuclear lamina that is dependent on breakdown and reformation of the nuclear envelope during mitosis. Moreover, tethering leads to the accumulation of lamin and INM proteins, but not to association with pericentromeric heterochromatin or nuclear pore complexes. Recruitment of genes to the INM can result in their transcriptional repression. Finally, we use targeted adenine methylation (DamID) to show that, as is the case for our model system, inactive immunoglobulin loci at the nuclear periphery are contacted by INM and lamina proteins. We propose that these molecular interactions may be used to compartmentalize and to limit the accessibility of immunoglobulin loci to transcription and recombination factors.
authors.affiliation: Howard Hughes Medical Institute, The University of Chicago, GCIS W522, 929 East 57th Street, Chicago, Illinois 60637, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Reddy
authors.forename: J M
authors.initials: JM
authors.lastname: Zullo
authors.forename: E
authors.initials: E
authors.lastname: Bertolino
authors.forename: H
authors.initials: H
authors.lastname: Singh
mesh_terms: D000107:Acetylation; D000225:Adenine / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D045584:Chromosome Positioning; D004268:DNA-Binding Proteins / Q000378:metabolism; D005347:Fibroblasts; D020868:Gene Silencing; D017930:Genes, Reporter / Q000235:genetics; D006657:Histones / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D034921:Lamin Type B / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008745:Methylation; D051379:Mice; D008938:Mitosis; D008957:Models, Genetic; D034881:Nuclear Lamina / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D006657:Histones; D007143:Immunoglobulin Heavy Chains; D034921:Lamin Type B; D008565:Membrane Proteins; D009687:Nuclear Proteins; C092710:emerin; C093413:lamina-associated polypeptide 2; D000225:Adenine