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S-phase phosphorylation of lamin B2
1Department of Biological Sciences, University of Dundee, Scotland, UK.
FEBS Letters
|December 11, 1995
Summary
Human diploid fibroblasts show changes in lamin B2 phosphorylation during the cell cycle. S-phase cells exhibit increased lamin B2 phosphorylation compared to quiescent cells, indicating cell cycle-specific modifications.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nuclear lamins are essential structural proteins of the nuclear envelope.
- Lamin B2 undergoes modifications during the cell cycle, but the specifics are not fully understood.
Purpose of the Study:
- To investigate the cell cycle-dependent phosphorylation of lamin B2 in human diploid fibroblasts.
- To identify specific modifications of lamin B2 during different phases of the cell cycle.
Main Methods:
- Synchronous cell cultures of human diploid fibroblasts (HDF).
- 2D gel electrophoresis and [32P]orthophosphate labeling.
- Immunoisolation of lamin B2 followed by tryptic peptide mapping.
Main Results:
- Lamin B2 phosphorylation significantly increases (2-3 fold) in S-phase HDF compared to G0 HDF.
- A unique phosphopeptide was detected in S-phase lamin B2, absent in G0.
- Phosphorylation occurred exclusively on serine residues, distinct from known cdc2 sites.
Conclusions:
- Lamin B2 phosphorylation is cell cycle-regulated, with a notable increase during the S-phase.
- These modifications suggest a role for lamin B2 phosphorylation in S-phase specific nuclear events.
- The identified phosphopeptide is not related to cdc2-mediated nuclear lamina breakdown.