Plasma membrane depolarization and Na,K-ATPase impairment induced by mitochondrial toxins augment leukemia cell apoptosis via a novel mitochondrial amplification mechanism

• Published in: Biochemical pharmacology 2009-07, Vol.78 (2), p.191-202
• Main Authors: Yin, Wu, Li, Xiang, Feng, Su, Cheng, Wei, Tang, Bo, Shi, Yi-Lin, Hua, Zi-Chun
• Format: Article
• Language: English
• Subjects: Adenosinetriphosphatase; Animals; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Biological and medical sciences; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Survival - drug effects; Cell Survival - physiology; Depolarization; Humans; Intracellular Membranes - drug effects; Intracellular Membranes - enzymology; Intracellular Membranes - metabolism; Jurkat Cells; Leukemia, T-Cell - enzymology; Leukemia, T-Cell - pathology; Medical sciences; Mice; Mice, Transgenic; Mitochondria; Mitochondrial Membranes - drug effects; Mitochondrial Membranes - enzymology; Mitochondrial Membranes - pathology; Na,K-ATPase; Pharmacology. Drug treatments; Reactive oxygen species; Rotenone - toxicity; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Sodium-Potassium-Exchanging ATPase - metabolism; T-Lymphocytes - cytology; T-Lymphocytes - drug effects; T-Lymphocytes - enzymology; U937 Cells
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2009.03.025

Na,K-ATPase is a ubiquitous transmembrane protein that regulates and maintains the intracellular Na + and K + gradient necessary for cell homeostasis. Recently, the importance of this pump in external stimuli-induced leukemia cell apoptosis has been increasingly appreciated, however, the exact role of Na,K-ATPase in mitochondrial apoptotic pathway still remains little understood. In this study, we found mitochondrial toxin rotenone caused a rapid mitochondrial membrane potential (MMP) collapse in Jurkat cells followed by plasma membrane depolarization (PMP). Similar results were also obtained in human U937 cells and non-cancerous mouse primary T cells. Rotenone-induced PMP depolarization occurred before apoptosis and well correlated with Na,K-ATPase impairment. To understand the mechanisms, Jurkat cells with mtDNA depletion and catalase overexpression were used. The results demonstrated that both PMP depolarization and Na,K-ATPase impairment induced by rotenone were regulated by mitochondrial H 2O 2 and Bcl-2. Finally, Na,K-ATPase suppression by ouabain greatly accelerated and enhanced mitochondrial toxins-induced cells apoptosis in Jurkat, U937 and primary T cells. In sum, by using leukemia cells and mouse primary T cells, we confirmed that mitochondria-to-Na,K-ATPase and PMP depolarization might represent a novel mechanism for mitochondria to amplify death signals in the initiation stage of cells apoptosis induced by mitochondrial toxins.