title: Structural organization of nuclear lamins A, C, B1, and B2 revealed by superresolution microscopy.
abstract: The nuclear lamina is a key structural element of the metazoan nucleus. However, the structural organization of the major proteins composing the lamina is poorly defined. Using three-dimensional structured illumination microscopy and computational image analysis, we characterized the supramolecular structures of lamin A, C, B1, and B2 in mouse embryo fibroblast nuclei. Each isoform forms a distinct fiber meshwork, with comparable physical characteristics with respect to mesh edge length, mesh face area and shape, and edge connectivity to form faces. Some differences were found in face areas among isoforms due to variation in the edge lengths and number of edges per face, suggesting that each meshwork has somewhat unique assembly characteristics. In fibroblasts null for the expression of either lamins A/C or lamin B1, the remaining lamin meshworks are altered compared with the lamin meshworks in wild-type nuclei or nuclei lacking lamin B2. Nuclei lacking LA/C exhibit slightly enlarged meshwork faces and some shape changes, whereas LB1-deficient nuclei exhibit primarily a substantial increase in face area. These studies demonstrate that individual lamin isoforms assemble into complex networks within the nuclear lamina and that A- and B-type lamins have distinct roles in maintaining the organization of the nuclear lamina.
authors: Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611.
authors: Takeshi
authors: T
authors: Shimi
authors: Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.
authors: Mark
authors: M
authors: Kittisopikul
authors: Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218.
authors: Joseph
authors: J
authors: Tran
authors: Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611.
authors: Anne E
authors: AE
authors: Goldman
authors: Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611.
authors: Stephen A
authors: SA
authors: Adam
authors: Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218.
authors: Yixian
authors: Y
authors: Zheng
authors: Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.
authors: Khuloud
authors: K
authors: Jaqaman
authors: Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 r-goldman@northwestern.edu khuloud.jaqaman@utsouthwestern.edu.
authors: Robert D
authors: RD
authors: Goldman
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007382:Intermediate Filaments / Q000378:metabolism; D051379:Mice; D008853:Microscopy / Q000379:methods; D009024:Morphogenesis; D034881:Nuclear Lamina / Q000737:chemistry / Q000378:metabolism*; D020033:Protein Isoforms
chemical_list: D020033:Protein Isoforms