Requirement for lamin B receptor and its regulation by importin β and phosphorylation in nuclear envelope assembly during mitotic exit

Xuelong Lu, Yang Shi, Quanlong Lu, Yan Ma, Jia Luo, Qingsong Wang, Jianguo Ji, Qing Jiang, Chuanmao Zhang

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Lamin B receptor (LBR), a chromatin and lamin B-binding protein in the inner nuclear membrane, has been proposed to target the membrane precursor vesicles to chromatin mediated by importin β during the nuclear envelope (NE) assembly. However, the mechanisms for the binding of LBR with importin β and the membrane targeting by LBR in NE assembly remain largely unknown. In this report, we show that the amino acids (aa) 69-90 of LBR sequences are required to bind with importin β at aa 45-462, and the binding is essential for the NE membrane precursor vesicle targeting to the chromatin during the NE assembly at the end of mitosis. We also show that this binding is cell cycle-regulated and dependent on the phosphorylation of LBR Ser-71 by p34 cdc2 kinase. RNAi knockdown of LBR causes the NE assembly failure and abnormal chromatin decondensation of the daughter cell nuclei, leading to the daughter cell death at early G1 phase by apoptosis. Perturbation of the interaction of LBR with importin β by deleting the LBR N-terminal spanning region or aa 69-73 also induces the NE assembly failure, the abnormal chromatin decondensation, and the daughter cell death. The first transmembrane domain of LBR promotes the NE production and expansion, because overexpressing this domain is sufficient to induce membrane overproduction of the NE. Thus, these results demonstrate that LBR targets the membrane precursor vesicles to chromatin by interacting with importin β in a LBR phosphorylation-dependent manner during the NE assembly at the end of mitosis and that the first transmembrane domain of LBR promotes the LBR-bearing membrane production and the NE expansion in interphase.

Original languageEnglish (US)
Pages (from-to)33281-33293
Number of pages13
JournalJournal of Biological Chemistry
Volume285
Issue number43
DOIs
StatePublished - Oct 22 2010
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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