A lamin-independent pathway for nuclear envelope assembly

J. W. Newport, K. L. Wilson, W. G. Dunphy

Research output: Contribution to journalArticlepeer-review

Abstract

The nuclear envelope is composed of membranes, nuclear pores, and a nuclear lamina. Using a cell-free nuclear assembly extract derived from Xenopus eggs, we have investigated how these three components interact during nuclear assembly. We find that the Xenopus embryonic lamin protein L(III) cannot bind directly to chromatin or membranes when each is present alone, but is readily incorporated into nuclei when both of the components are present together in an assembly extract. We find that depleting lamin L(III) from an extract does not prevent formation of an envelope consisting of membranes and nuclear pores. However, these lamin-depleted envelopes are extremely fragile and fail to grow beyond a limited extent. This suggests that lamin assembly is not required during the initial steps of nuclear envelope formation, but is required for later growth and for maintaining the structural integrity of the envelope. We also present results showing that lamins may only be incorporated into nuclei after DNA has been encapsulated within an envelope and nuclear transport has been activated. With respect to nuclear function, our results show that the presence of a nuclear lamina is required for DNA synthesis to occur within assembled nuclei.

Original languageEnglish (US)
Pages (from-to)2247-2259
Number of pages13
JournalJournal of Cell Biology
Volume111
Issue number6 I
DOIs
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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