The pro-apoptotic protein Bim is a convergence point for cAMP/protein kinase A- and glucocorticoid-promoted apoptosis of lymphoid cells.

Abstract

The mechanisms by which cAMP mediates apoptosis are not well understood. In the current studies, we used wild-type (WT) S49 T-lymphoma cells and the kin(-) variant (which lacks protein kinase A (PKA)) to examine cAMP/PKA-mediated apoptosis. The cAMP analog, 8-CPT-cAMP, increased phosphorylation of the cAMP response element-binding protein (CREB), activated caspase-3, and induced apoptosis in WT but not in kin(-) S49 cells. Using an array of 96 apoptosis-related genes, we found that treatment of WT cells with 8-CPT-cAMP for 24 h induced expression of mRNA for the pro-apoptotic gene, Bim. Real-time PCR analysis indicated that 8-CPT-cAMP increased Bim RNA in WT cells in <2 h and maintained this increase for >24 h. Bim protein expression increased in WT but not kin(-) cells treated with 8-CPT-cAMP or with the beta-adrenergic receptor agonist isoproterenol. Both apoptosis and Bim expression were reversible with removal of 8-CPT-cAMP after <6 h. The glucocorticoid dexamethasone also promoted apoptosis and Bim expression in S49 cells. In contrast, both UV light and anti-mouse Fas monoclonal antibody promoted apoptosis in S49 cells but did not induce Bim expression. 8-CPT-cAMP also induced Bim expression and enhanced dexamethasone-promoted apoptosis in human T-cell leukemia CEM-C7-14 (glucocorticoid-sensitive) and CEM-C1-15 (glucocorticoid-resistant) cells; increased Bim expression in 8-CPT-cAMP-treated CEM-C1-15 cells correlated with conversion of the cells from resistance to sensitivity to glucocorticoid-promoted apoptosis. Induction of Bim appears to be a key event in cAMP-promoted apoptosis in both murine and human T-cell lymphoma and leukemia cells and thus appears to be a convergence point for the killing of such cells by glucocorticoids and agents that elevate cAMP.

• Authors: Lingzhi Zhang, Paul A Insel
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 279 Issue 20 Pg. 20858-65 (May 14 2004) ISSN: 0021-9258 [Print] United States
• PMID: 14996839 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Apoptosis Regulatory Proteins
• BCL2L11 protein, human
• Bcl-2-Like Protein 11
• Bcl2l11 protein, mouse
• Carrier Proteins
• Glucocorticoids
• Membrane Proteins
• Proto-Oncogene Proteins
• RNA, Messenger
• Recombinant Proteins
• Thionucleotides
• 8-((4-chlorophenyl)thio)cyclic-3',5'-AMP
• Dexamethasone
• Cyclic AMP
• Cyclic AMP-Dependent Protein Kinases
• Isoproterenol

Topics

• Animals
• Apoptosis (drug effects, physiology)
• Apoptosis Regulatory Proteins
• Bcl-2-Like Protein 11
• Binding Sites
• Carrier Proteins (genetics, metabolism)
• Cell Cycle
• Cell Line, Tumor
• Cyclic AMP (analogs & derivatives, pharmacology)
• Cyclic AMP-Dependent Protein Kinases (metabolism)
• Dexamethasone (pharmacology)
• Flow Cytometry
• Gene Expression Regulation, Neoplastic (genetics)
• Glucocorticoids (pharmacology)
• Humans
• Isoproterenol (pharmacology)
• Kinetics
• Lymphoma, T-Cell (pathology)
• Membrane Proteins (genetics, metabolism)
• Mice
• Proto-Oncogene Proteins (genetics, metabolism)
• RNA, Messenger (genetics)
• Recombinant Proteins (metabolism)
• Thionucleotides (pharmacology)
• Transfection