title: Cytotoxic T lymphocyte antigen-2 alpha induces apoptosis of murine T-lymphoma cells and cardiac fibroblasts and is regulated by cAMP/PKA.
abstract: The mechanism of cAMP-promoted apoptosis is not well defined. In wild-type (WT) murine S49 lymphoma cells, cAMP promotes apoptosis in a protein kinase A (PKA)-dependent manner. We find that treatment of WT S49 cells with 8-CPT-cAMP prominently increases the expression (as determined by DNA microarray analysis, real-time PCR and immunblotting) of cytotoxic T lymphocyte antigen-2α (CTLA-2α), a cathepsin L-like cysteine protease inhibitor. By contrast, CTLA-2α expression is only slightly increased by 8-CPT-cAMP treatment of D-S49 cells, which lack cAMP/PKA-promoted apoptosis. Raising endogenous cAMP (by use of forskolin or inhibition of phosphodiesterase [PDE] 4) or a PKA-selective, but not an Epac-selective, cAMP analogue, increases CTLA-2α mRNA expression; PKA, and not Epac, thus mediates the increase in CTLA-2α expression. An adenoviral CLTA-2α (Ad-CTLA-2α) construct induces apoptosis and enhances cAMP-promoted apoptosis in WT S49 cells but such cells do not have an increase in cathepsin L activity nor does a cathepsin L inhibitor alter cAMP-promoted apoptosis. 8-CPT-cAMP also increases CTLA-2α expression and induces apoptosis in murine cardiac fibroblasts; knockdown of CTLA-2α expression by siRNA blocks 8-CPT-cAMP-promoted apoptosis. Thus, cAMP increases CTLA-2α expression in murine lymphoma and cardiac fibroblasts and this increase in CTLA-2α contributes to cAMP/PKA-promoted apoptosis by mechanisms that are independent of the ability of CTLA-2α to inhibit cathepsin L.
authors.affiliation: Department of Pharmacology, La Jolla, CA 92093, USA.
authors.forename: Lingzhi
authors.initials: L
authors.lastname: Zhang
authors.forename: Hongruo
authors.initials: H
authors.lastname: Yun
authors.forename: Fiona
authors.initials: F
authors.lastname: Murray
authors.forename: Ruilin
authors.initials: R
authors.lastname: Lu
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Vivian
authors.initials: V
authors.lastname: Hook
authors.forename: Paul A
authors.initials: PA
authors.lastname: Insel
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism*; D017209:Apoptosis; D056668:Cathepsin L / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D015151:Immunoblotting; D016399:Lymphoma, T-Cell / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D034741:RNA, Small Interfering; D013873:Thionucleotides / Q000494:pharmacology*; D014162:Transfection
chemical_list: D000943:Antigens, Differentiation; D034741:RNA, Small Interfering; D013873:Thionucleotides; C102076:cytotoxic T-lymphocyte antigen-2, mouse; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases; D056668:Cathepsin L