title: Spermine signalling in tobacco: activation of mitogen-activated protein kinases by spermine is mediated through mitochondrial dysfunction.
abstract: Polyamines (PAs) play important roles in cell proliferation, growth and environmental stress responses of all living organisms. In this study, we examine whether these compounds act as signal mediators. Spermine (Spm) specifically activated protein kinases of tobacco leaves, which were identified as salicylic acid (SA)-induced protein kinase (SIPK) and wound-induced protein kinase (WIPK), using specific antibodies. Upon Spm treatment, upregulation of WIPK, but not SIPK, was observed. Spm-induced mitogen-activated protein kinases (MAPKs) activation and WIPK upregulation were prevented upon pre-treatment with antioxidants and Ca2+ channel blockers. Additionally, Spm specifically stimulated expression of the alternative oxidase (AOX) gene, which was disrupted by these antioxidants and Ca2+ channel blockers. Bongkrekic acid (BK), an inhibitor of the opening of mitochondrial permeability transition (PT) pores, suppressed MAPKs activation and accumulation of WIPK and AOX mRNA. Our data collectively suggest that Spm causes mitochondrial dysfunction via a signalling pathway in which reactive oxygen species and Ca2+ influx are involved. As a result, the phosphorylation activities of the two MAPK enzymes SIPK and WIPK are stimulated.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Thomas
authors.initials: T
authors.lastname: Berberich
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Shigemi
authors.initials: S
authors.lastname: Seo
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Kusano
mesh_terms: D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D024101:Mitochondrial Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008970:Molecular Weight; D010088:Oxidoreductases / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology; D010940:Plant Proteins; D030821:Plants, Genetically Modified / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D013096:Spermine / Q000494:pharmacology* / Q000502:physiology*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics; D000099188:Alternative Oxidase
chemical_list: D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D004121:Dimethyl Sulfoxide; D024101:Mitochondrial Proteins; D020928:Mitogen-Activated Protein Kinases; D010088:Oxidoreductases; D010940:Plant Proteins; D013096:Spermine; D000099188:Alternative Oxidase