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The proapoptotic factor BIM is necessary and sufficient for cAMP/PKA‐induced apoptosis in murine S49 lymphoma cells
Author(s) -
Zambon Alex C,
Ho Angela,
Wilderman Andrea,
Seibold Millie,
Insel Paul A
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1056.2
Subject(s) - apoptosis , protein kinase a , microbiology and biotechnology , gene knockdown , gs alpha subunit , programmed cell death , intracellular , second messenger system , chemistry , biology , signal transduction , kinase , g protein , biochemistry
The intracellular second messenger cyclic AMP (cAMP) acts via protein kinase A (PKA) to induce G 1 phase cell‐cycle arrest by 24h and subsequent apoptosis at 48h in murine S49 lymphoma cells. The molecular mechanisms for cAMP/PKA growth arrest and killing are undefined. Using genome‐wide microarray analysis, we found that treatment of WT and Deathless (D‐) S49 cells with the PKA agonist 8‐(4‐chlorophenylthio)‐cAMP (CPT‐cAMP) differentially regulates several pro‐ and anti‐apoptotic transcripts at 24 h, thus identifying putative mediators of cAMP/PKA killing. The D‐ (cAMP‐deathless) S49 cell variant has wild‐type levels of PKA activity, undergoes cAMP‐promoted G 1 growth arrest but is protected from cAMP/PKA‐induced apoptosis by an unknown mechanism. We hypothesized that the pro‐apoptotic BH3‐only family member Bim, which shows increased expression in WT, but not D‐cells 24h after CPT‐cAMP treatment, is a key mediator of PKA‐mediated killing in S49 cells. Conditional expression of the BimL isoform in both WT and D‐ S49 cells dose‐dependently increased apoptosis in both cell lines, indicating that its up‐regulation is sufficient to induce apoptosis of S49 cells. Furthermore, inhibition of cAMP‐mediated BimL induction via short hairpin RNAi knockdown studies abolished CPT‐cAMP‐mediated apoptosis of WT S49 cells, indicating that Bim up‐regulation by PKA is necessary for PKA‐mediated apoptosis. Taken together, these results indicate that the transcriptional up‐regulation of the pro‐apoptotic protein Bim is necessary and sufficient for cAMP/PKA‐mediated apoptosis.