Lamin B is rapidly phosphorylated in lymphocytes after activation of protein kinase C.
Lamin B was shown to be a major substrate of cellular phosphorylation in the response of lymphocytes to phorbol esters. Lamins A and C, which were not observed in lymphocytes, were also substrates of phorbol-stimulated phosphorylation in those cell types that express them. Lamin B phosphopeptides labeled with 32P in intact cells treated with phorbol 12-myristate 13-acetate were compared to those produced by in vitro phosphorylation with protein kinase M, cAMP-dependent protein kinase, and Ca2+/calmodulin-dependent protein kinase II. The phosphopeptides labeled by in vivo stimulation with phorbol esters are very similar to those phosphorylated in vitro by protein kinase M, a catalytic domain of protein kinase C. Phorbol treatment of interphase cells significantly reduces the amount of detergent-insoluble lamin B, suggesting that phosphorylation of lamin may alter the architecture of the nuclear lamina. In addition, we have shown that treatment of a B-cell line with antibodies to IgM induces a modest increase in lamin B phosphorylation. These results strongly suggest that ligands that are known to activate protein kinase C at the cell surface or in the cytosol also lead to the activation of a nuclear kinase activity with a protein kinase C-type specificity.
Hornbeck
P
P
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892.
Huang
K P
KP
Paul
W E
WE
D000818:Animals; D006224:Cricetinae; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D034921:Lamin Type B; D034882:Lamins; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000378:metabolism
D034921:Lamin Type B; D034882:Lamins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011494:Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate