title: Mechanisms of nuclear lamina growth in interphase.
abstract: The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) to the nuclear periphery. Yet, the lamina is a dynamic structure demonstrating considerable expansion during the cell cycle to accommodate increased number of LADs formed during DNA replication. We analyzed dynamics of nuclear growth during interphase and changes in lamina structure as a function of cell cycle progression. The nuclear lamina demonstrates steady growth from G1 till G2, while quantitative analysis of lamina meshwork by super-resolution microscopy revealed that microdomain organization of the lamina is maintained, with lamin A and lamin B microdomain periodicity and interdomain gap sizes unchanged. FRAP analysis, in contrast, demonstrated differences in lamin A and B1 exchange rates; the latter showing higher recovery rate in S-phase cells. In order to further analyze the mechanism of lamina growth in interphase, we generated a lamina-free nuclear envelope in living interphase cells by reversible hypotonic shock. The nuclear envelope in nuclear buds formed after such a treatment initially lacked lamins, and analysis of lamina formation revealed striking difference in lamin A and B1 assembly: lamin A reassembled within 30 min post-treatment, whereas lamin B1 did not incorporate into the newly formed lamina at all. We suggest that in somatic cells lamin B1 meshwork growth is coordinated with replication of LADs, and lamin A meshwork assembly seems to be chromatin-independent process.
authors.affiliation: Department of Electron Microscopy, A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia.
authors.forename: Oxana A
authors.initials: OA
authors.lastname: Zhironkina
authors.affiliation: Department of Electron Microscopy, A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia.
authors.forename: Svetlana Yu
authors.initials: SY
authors.lastname: Kurchashova
authors.affiliation: Faculty of Chemistry, Lomonosov Moscow State University, 1-3 Leninskie Gory, Moscow, Russia.
authors.forename: Vasilisa A
authors.initials: VA
authors.lastname: Pozharskaia
authors.affiliation: Department of Electron Microscopy, A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia.
authors.forename: Varvara D
authors.initials: VD
authors.lastname: Cherepanynets
authors.affiliation: Department of Electron Microscopy, A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia.
authors.forename: Olga S
authors.initials: OS
authors.lastname: Strelkova
authors.affiliation: Institute of Molecular Genetics of the ASCR, v. v. i. Vídeňská 1083, 142 20, Prague 4, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Hozak
authors.affiliation: Department of Electron Microscopy, A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia. kireev@genebee.msu.ru.|Faculty of Biology, Lomonosov Moscow State University, 1-40 Leninskie Gory, Moscow, Russia. kireev@genebee.msu.ru.
authors.forename: Igor I
authors.initials: II
authors.lastname: Kireev
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003412:Cricetulus; D006801:Humans; D007399:Interphase; D051379:Mice; D034881:Nuclear Lamina / Q000737:chemistry / Q000378:metabolism*; D013552:Swine
keywords: Cell cycle; DNA replication; Interphase; Microdomains; Nuclear lamina; Nucleus