Effect of endogenous catecholamines on apoptosis of Con A-activated lymphocytes of rats.
Our previous studies show that lymphocytes express tyrosine hydroxylase (TH) and synthesize catecholamines (CAs) including dopamine, epinephrine and norepinephrine, and that the lymphocytes-derived endogenous CAs affect function of lymphocytes via autocrine/paracrine pathways. Over recent years, induction of apoptosis has been suggested to be a possible mechanism underlying the endogenous CAs-mediated lymphocyte proliferation, differentiation and activation. However, direct effect of the lymphocytes-synthesized CAs on lymphocyte apoptosis is less known. In the present study, TH inhibitor alpha-methyl-p-tyrosine (alpha-MT) and monoamine oxydase inhibitor pargyline were employed to block the synthesis and degradation of CAs in lymphocytes activated by concanavalin A (Con A). Apoptotic cells and apoptosis-related genes and proteins, Bax, Bcl-2, Fas, Fas-Ligand (FasL) and caspase-3, were examined in the lymphocytes treated with alpha-MT or pargyline by means of Annexin V/propidium iodide (PI) staining, real-time PCR and Western blot analyses, respectively. The treatment with alpha-MT of 10(-6) M and 10(-5) M (not 10(-7) M) notably reduced intracellular and supernatant DA, E and NE of the Con A-activated lymphocytes in a dose-dependent manner, and correspondingly, the treatment induced a remarkable decrease of apoptotic lymphocytes but not necrotic cells. The expression of Bax, Fas, FasL and caspase-3 mRNAs and proteins was significantly inhibited in the Con A-activated lymphocytes after the cells were treated with alpha-MT of 10(-6) M and 10(-5) M; but the expression of Bcl-2 mRNA and protein was dramatically increased by the alpha-MT treatment. Contrarily, the treatment with pargyline of 10(-6) M and 10(-5) M (not 10(-7) M) evidently increased the intracellular and supernatant DA, E and NE contents of the Con A-activated lymphocytes in a dose-dependent manner, and meanwhile, it caused a striking increase of apoptotic lymphocytes but not necrotic cells. The expression of Bax, Fas, FasL and caspase-3 mRNAs and proteins in the Con A-stimulated lymphocytes was remarkably enhanced by the treatment with pargyline of 10(-6) M and 10(-5) M, but the expression of Bcl-2 mRNA and protein was notably attenuated by the pargyline treatment. These results imply that endogenous CAs synthesized and secreted by lymphocytes accelerate lymphocyte apoptosis by altering fine balance between the expression of antiapoptotic and proapoptotic markers at transcriptional and translational levels, and suggest that both the death receptor pathway and the mitochondrial pathway are involved in the endogenous CAs-induced apoptosis.
Jiang
Jian-Lan
JL
Department of Biological Science and Technology, School of Life Sciences, Mailbox 426, Nanjing University, Nanjing 210093, China.
Peng
Yu-Ping
YP
Qiu
Yi-Hua
YH
Wang
Jian-Jun
JJ
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000187:drug effects*; D008934:Mitogens / Q000494:pharmacology*; D010293:Pargyline / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D019805:alpha-Methyltyrosine / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
D002395:Catecholamines; D004791:Enzyme Inhibitors; D053222:Fas Ligand Protein; C491898:Fas protein, rat; D008934:Mitogens; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D003208:Concanavalin A; D019805:alpha-Methyltyrosine; D010293:Pargyline; D053148:Caspase 3