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Distinct functions of down-regulation-sensitive and -resistant types of protein kinase C in rabbit aortic smooth

K Kariya, Y Takai

    FEBS Letters
    |July 13, 1987
    PubMed

    Insights

    Protein kinase C (PKC) in rabbit aortic cells has two types: one affects cell proliferation, while the other regulates calcium. Down-regulation reveals distinct PKC functions in smooth muscle cells.

    Area of Science:

    • Cell Biology
    • Biochemistry

    Background:

    • Protein kinase C (PKC) plays a role in cellular signaling pathways.
    • PKC is involved in regulating cell proliferation and calcium homeostasis.

    Purpose of the Study:

    • To investigate the distinct roles of different types of PKC in rabbit aortic smooth muscle cells.
    • To understand the effects of PKC down-regulation on cell proliferation and calcium signaling.

    Main Methods:

    • Rabbit aortic smooth muscle cells were cultured and treated with phorbol esters (TPA and PDBu).
    • DNA synthesis was measured to assess cell proliferation.
    • Cytoplasmic free Ca2+ concentration ([Ca2+]i) was monitored.
    • PKC levels were determined after prolonged PDBu treatment.

    Main Results:

    • 12-O-tetradecanoylphorbol-13-acetate (TPA) induced DNA synthesis and inhibited whole blood serum (WBS)-induced DNA synthesis and [Ca2+]i.
    • Prolonged phorbol-12,13-dibutyrate (PDBu) treatment down-regulated PKC to 25-35% of control levels.
    • In PDBu-pretreated cells, TPA lost its proliferative and antiproliferative effects but retained its ability to inhibit WBS-induced [Ca2+]i increase.

    Conclusions:

    • Rabbit aortic smooth muscle cells possess both down-regulation-sensitive and -resistant types of PKC.
    • The down-regulation-sensitive PKC mediates proliferative and antiproliferative actions.
    • The down-regulation-resistant PKC inhibits WBS-induced [Ca2+]i increase but lacks proliferative/antiproliferative roles.

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