title: Role of c-Jun N-terminal kinase activation in apoptosis induced by removal of the growth factors.
abstract: Apoptosis plays a crucial role for generation of lymphocyte repertoire, clonal contraction, and elimination of virus-infected cells. Since IL-3-dependent pro-B cell line Baf-3 resulted in rapid induction of apoptotic cell death upon IL-3 withdrawal, it would by very valuable for analysis of apoptosis induction by growth factor deprivation. First, we confirmed that Baf-3 cells underwent loss of mitochondrial membrane potential (ΔΨm) and apoptosis in a time-dependent manner when they were cultured in the RPMI-1640 medium without IL-3. Induction of apoptosis and loss of ΔΨm was determined by DiOC6 and annexin V staining method using flow cytometer, respectively. Deprivation of IL-3 induced upregulation of proapoptotic molecule Bax, in conjunction with slight down-regulation of anti-apoptotic molecule Bcl-xL, which was assessed by Western blotting. Since Bcl-xL-overexpressing Baf-3 cells showed some resistance to IL-3-deprivation, Bcl-xL prevents apoptosis induced by IL-3 withdrawal. Finally, a sustained JNK1 activation was observed prior to induction of apoptosis upon IL-3 deprivation. Dominat-negative form of JNK1 and JNK inhibitor sp600125 partially inhibit the apoptosis upon IL-3 deprivation, suggesting that a sustained JNK1 activation was involved in the induction of apoptosis. Together, IL-3 deprivation of IL-3-dependent cell line Baf-3 induces a sustained JNK1 activation, followed by a decline of the ratio of Bcl-xL to Bax, leading to loss of DCm, and finally apoptosis.
authors.affiliation: School of Mathematics, Physics and Biology Engineering, Inner Mongolia University of Science and Technology, Baotou, 014010, China.
authors.forename: Yue-Bao
authors.initials: YB
authors.lastname: Ning
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Du
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency* / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D007377:Interleukin-3; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D048031:JNK Mitogen-Activated Protein Kinases
keywords: Baf-3 cells; Bcl-2 family protein; c-Jun N-terminal kinase; cell apoptosis