Roles of LAP2 proteins in nuclear assembly and DNA replication: Truncated LAP2β proteins alter lamina assembly, envelope formation, nuclear size, and DNA replication efficiency in Xenopus laevis extracts

Tracey Michele Gant, Crafford A. Harris, Katherine L. Wilson

Research output: Contribution to journalArticle

Abstract

Humans express three major splicing isoforms of LAP2, a lamin- and chromatin-binding nuclear protein. LAP2β and γ are integral membrane proteins, whereas α is intranuclear. When truncated recombinant human LAP2β proteins were added to cell-free Xenopus laevis nuclear assembly reactions at high concentrations, a domain common to all LAP2 isoforms (residues 1-187) inhibited membrane binding to chromatin, whereas the chromatin- and lamin- binding region (residues 1-408) inhibited chromatin expansion. At lower concentrations of the common domain, membranes attached to chromatin with a unique scalloped morphology, but these nuclei neither accumulated lamins nor replicated. At lower concentrations of the chromatin and lamin-binding region, nuclear envelopes and lamins assembled, but nuclei failed to enlarge and replicated on average 2.5-fold better than controls. This enhancement was not due to rereplication, as shown by density substitution experiments, suggesting the hypothesis that LAP2β is a downstream effector of lamina assembly in promoting replication competence. Overall, our findings suggest that LAP2 proteins mediate membrane-chromatin attachment and lamina assembly, and may promote replication by influencing chromatin structure.

Original languageEnglish (US)
Pages (from-to)1083-1096
Number of pages14
JournalJournal of Cell Biology
Volume144
Issue number6
DOIs
StatePublished - Mar 22 1999

Keywords

  • Chromatin structure
  • Emerin
  • MAN
  • Nuclear envelope
  • Prereplication complex

ASJC Scopus subject areas

  • Cell Biology

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