The role of lamin LIII in nuclear assembly and DNA replication, in cell-free extracts of Xenopus eggs.
Xenopus egg extracts, which support nuclear assembly and DNA replication, were functionally depleted of lamin LIII by inoculating them with monoclonal anti-lamin antibodies. Phase-contrast microscopy and electron-microscopy studies indicated that lamin-depleted extracts supported efficient chromatin decondensation, and assembly of double membrane structures and nuclear pores on demembranated sperm heads. Immunofluorescence microscopy suggests that lamin-antibody complexes are transported across the nuclear membrane but do not assemble into a lamina. These findings were confirmed by immunoblotting analysis of isolated nuclei. Metabolic labelling studies with either biotin-11-dUTP or [32P]dCTP, revealed that nuclei lacking a lamina were unable to initiate DNA replication and that, although such nuclei could import proteins required for DNA replication (e.g. PCNA), these proteins were apparently not organized into replicon clusters.
Meier
J
J
Department of Biological Sciences, University, Dundee, Scotland.
Campbell
K H
KH
Ford
C C
CC
Stick
R
R
Hutchison
C J
CJ
D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002843:Chromatin / Q000737:chemistry*; D004261:DNA Replication; D005260:Female; D034882:Lamins; D008297:Male; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000378:metabolism* / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000276:immunology / Q000502:physiology*; D010063:Ovum / Q000648:ultrastructure; D011233:Precipitin Tests; D013077:Sperm Head / Q000648:ultrastructure; D014981:Xenopus / Q000502:physiology
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002843:Chromatin; D034882:Lamins; D009687:Nuclear Proteins