title: Nuclear structures surrounding internal lamin invaginations.
abstract: A- and C-type lamins are intermediate filament proteins responsible for the maintenance of nuclear shape and most likely nuclear architecture. Here, we propose that pronounced invaginations of A/C-type lamins into the nuclear interior represent channels for the transport of regulatory molecules to and from nuclear and nucleolar regions. Using fluorescent protein technology and immunofluorescence, we show that A-type lamin channels interact with several nuclear components, including fibrillarin- and UBF-positive regions of nucleoli, foci of heterochromatin protein 1 β, polycomb group bodies, and genomic regions associated with DNA repair. Similar associations were observed between A/C-type lamin channels and nuclear pores, lamin-associated protein LAP2α, and promyelocytic leukemia nuclear bodies. Interestingly, regions with high levels of A/C-type lamins had low levels of B-type lamins, and vice versa. These characteristics were observed in primary and immortalized mouse embryonic fibroblasts as well as human and mouse embryonic stem cell colonies exhibiting stem cell-specific lamin positivity. Our findings indicate that internal channels formed by nuclear lamins likely contribute to normal cellular processes through association with various nuclear and nucleolar structures.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65, Brno, Czech Republic.
authors.forename: Soňa
authors.initials: S
authors.lastname: Legartová
authors.forename: Lenka
authors.initials: L
authors.lastname: Stixová
authors.forename: Oskar
authors.initials: O
authors.lastname: Laur
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
authors.forename: Petra
authors.initials: P
authors.lastname: Sehnalová
authors.forename: Eva
authors.initials: E
authors.lastname: Bártová
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000648:ultrastructure; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D034904:Lamin Type A / Q000648:ultrastructure*; D034921:Lamin Type B / Q000648:ultrastructure*; D008565:Membrane Proteins / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D034904:Lamin Type A; D034921:Lamin Type B; D008565:Membrane Proteins; C047458:fibrillarin; C440308:lamin C; C093413:lamina-associated polypeptide 2
keywords: CHROMATIN; DNA REPAIR; ES CELLS; HP1 PROTEIN; LAMINS; NUCLEAR PORES; PML BODIES; TRANSCRIPTION