A mitotic lamin B matrix induced by RanGTP required for spindle assembly.
Mitotic spindle morphogenesis is a series of highly coordinated movements that lead to chromosome segregation and cytokinesis. We report that the intermediate filament protein lamin B, a component of the interphase nuclear lamina, functions in spindle assembly. Lamin B assembled into a matrix-like network in mitosis through a process that depended on the presence of the guanosine triphosphate-bound form of the small guanosine triphosphatase Ran. Depletion of lamin B resulted in defects in spindle assembly. Dominant negative mutant lamin B proteins that disrupt lamin B assembly in interphase nuclei also disrupted spindle assembly in mitosis. Furthermore, lamin B was essential for the formation of the mitotic matrix that tethers a number of spindle assembly factors. We propose that lamin B is a structural component of the long-sought-after spindle matrix that promotes microtubule assembly and organization in mitosis.
Tsai
Ming-Ying
MY
Department of Embryology, Carnegie Institution of Washington and Howard Hughes Medical Institute, Baltimore, MD 21218, USA.
Wang
Shusheng
S
Heidinger
Jill M
JM
Shumaker
Dale K
DK
Adam
Stephen A
SA
Goldman
Robert D
RD
Zheng
Yixian
Y
D000818:Animals; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D034921:Lamin Type B / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis; D034622:RNA Interference; D008941:Spindle Apparatus / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D014981:Xenopus; D028901:alpha Karyopherins / Q000378:metabolism; D028961:beta Karyopherins / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000502:physiology*
D034921:Lamin Type B; D028901:alpha Karyopherins; D028961:beta Karyopherins; D006160:Guanosine Triphosphate; D020931:ran GTP-Binding Protein