Overexpression of MARCKS, but not protein kinase C-alpha, increases phorbol ester-stimulated synthesis of phosphatidylcholine in human SK-N-MC neuroblastoma cells.
To investigate the regulation of phorbol ester-stimulated synthesis of phosphatidylcholine (PtdCho), myristoylated alanine-rich protein kinase C substrate (MARCKS) and the alpha-isoform of protein kinase C (PKC-alpha) were overexpressed in a human neuroblastoma (SK-N-MC) cell line that does not increase PtdCho synthesis in response to 4beta-12-O-tetradecanoylphorbol 13-acetate (TPA). In five clones with a less than fivefold increase in MARCKS protein level, the synthesis of PtdCho from [methyl-3H] choline was stimulated 1.88-2.34-fold in the presence of 100-200 nM TPA. In clones overexpressing PKC-alpha (30-40-fold increased level of protein) or in mock-transfected vector controls, TPA had much less of a stimulatory effect (1.04-1.43 fold) on PtdCho synthesis. TPA caused translocation of PKC-alpha and increased phosphorylation of MARCKS, indicating that both overexpressed proteins responded to stimulation. Thus, in SK-N-MC cells, MARCKS is required for TPA-stimulated synthesis of PtdCho and PKC-alpha alone is insufficient for supporting enhanced synthesis.
Rose
S D
SD
Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
Morash
S C
SC
Ridgway
D N
DN
Byers
D M
DM
Cook
H W
HW
D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000502:physiology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009447:Neuroblastoma; D010713:Phosphatidylcholines / Q000096:biosynthesis* / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology*; D051571:Protein Kinase C-alpha; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology
D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; C000619710:MARCKS protein, human; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D011506:Proteins; D012333:RNA, Messenger; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D013755:Tetradecanoylphorbol Acetate