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Preparation of Primary Acute Lymphoblastic Leukemia Cells in Different Cell Cycle Phases by Centrifugal Elutriation
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Published on: November 10, 2017

Altered regulation of cyclic AMP-dependent protein kinase in a mouse lymphoma cell line

M Lasser, V Daniel

    Biochimica Et Biophysica Acta
    |May 12, 1977
    PubMed

    Insights

    Mouse lymphoma cells resistant to cyclic AMP exhibit altered cyclic AMP-dependent protein kinase. This resistance stems from a structural change in the regulatory subunit, affecting cyclic AMP binding and kinase activity.

    Area of Science:

    • Biochemistry
    • Cell Biology
    • Molecular Pharmacology

    Background:

    • Cyclic adenosine monophosphate (cAMP) regulates crucial cellular processes including growth inhibition, cytolysis, and phosphodiesterase synthesis in S49.1 mouse lymphoma cells.
    • Selection for resistance to dibutyryl cAMP revealed a deficiency in these cAMP-mediated cellular responses.

    Purpose of the Study:

    • To comparatively analyze the properties of cAMP-dependent protein kinase (PKA) in cAMP-sensitive (S) and cAMP-resistant (R) mouse lymphoma cells.
    • To elucidate the molecular basis for cAMP resistance in S49.1 lymphoma cells.

    Main Methods:

    • Comparative biochemical analysis of PKA activity, substrate affinity, and heat stability in S and R cell lines.
    • Characterization of regulatory and catalytic subunit properties in response to varying cAMP concentrations.

    Main Results:

    • PKA from R cells showed a 100-fold higher apparent Ka for cAMP activation compared to S cells.
    • The holoenzyme of R kinase exhibited increased heat stability over S kinase, particularly at higher cAMP concentrations.
    • The regulatory subunit of R kinase formed a heat-stable complex with cAMP only at high cAMP concentrations, unlike S kinase.

    Conclusions:

    • The transition to a cAMP-resistant phenotype in lymphoma cells is associated with a structural alteration in the regulatory subunit of PKA.
    • This alteration impacts the regulatory subunit's affinity for cAMP and its interaction with the catalytic subunit, leading to altered kinase function.

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