title: Cryptogein-induced cell cycle arrest at G2 phase is associated with inhibition of cyclin-dependent kinases, suppression of expression of cell cycle-related genes and protein degradation in synchronized tobacco BY-2 cells.
abstract: Induction of defense responses by pathogens or elicitors is often accompanied by growth inhibition in planta, but its molecular mechanisms are poorly understood. In this report, we characterized the molecular events that occur during cryptogein-induced cell cycle arrest at G(2) phase in synchronously cultured tobacco Bright Yellow-2 (BY-2) cells. Concomitant with the proteinaceous elicitor-induced G(2) arrest, we observed inhibition of the histone H1 kinase activity of cyclin-dependent kinases (CDKs), which correlated with a decrease in mRNA and protein levels of CDKB1. In contrast, the amount of CDKA was almost unaffected by cryptogein even at M phase. Cryptogein rapidly inhibited the expression not only of positive, e.g. A- and B-type cyclins and NtCAK, but also of negative cell cycle regulators such as WEE1, suggesting that cryptogein affects multiple targets to inactivate CDKA to induce G(2) arrest by mechanisms distinct from known checkpoint regulation. Moreover, we show that CDKB1 and cyclin proteins are also rapidly degraded by cryptogein and that the proteasome-dependent protein degradation has a crucial role in the control of cryptogein-induced hypersensitive cell death.
authors.affiliation: Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Ohno
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kadota
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Fujii
authors.forename: Masami
authors.initials: M
authors.lastname: Sekine
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kuchitsu
mesh_terms: D020418:Algal Proteins / Q000494:pharmacology*; D016923:Cell Death; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005656:Fungal Proteins; D016195:G2 Phase / Q000187:drug effects* / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D018816:Genes, cdc; D049452:Green Fluorescent Proteins; D008938:Mitosis / Q000187:drug effects; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D061988:Proteasome Inhibitors; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000187:drug effects; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D016213:Cyclins; D005656:Fungal Proteins; D010940:Plant Proteins; D061988:Proteasome Inhibitors; D012333:RNA, Messenger; D014157:Transcription Factors; C061032:cryptogein protein, Phytophthora cryptogea; D049452:Green Fluorescent Proteins; D018844:Cyclin-Dependent Kinases