Journal Article

MAP Kinases Function Downstream of HSP90 and Upstream of Mitochondria in TMV Resistance Gene <i>N</i>-Mediated Hypersensitive Cell Death

Reona Takabatake, Yuko Ando, Shigemi Seo, Shinpei Katou, Shinya Tsuda, Yuko Ohashi and Ichiro Mitsuhara

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 3, pages 498-510
Published in print March 2007 | ISSN: 0032-0781
Published online March 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm021
MAP Kinases Function Downstream of HSP90 and Upstream of Mitochondria in TMV Resistance Gene N-Mediated Hypersensitive Cell Death

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Although the involvement of heat shock protein 90 (HSP90), mitogen-activated protein kinase (MAPK) cascades and organelle dysfunction in plant hypersensitive cell death has been suggested, the mutual relationship among them has not been elucidated. Here, we show the molecular network of HSP90, the wound-induced protein kinase (WIPK)/salicylic acid-induced protein kinase (SIPK)-mediated MAPK cascade and mitochondrial dysfunction in tobacco mosaic virus (TMV) resistance gene N-dependent cell death. p50, the Avr component for N, NtMEK2DD, a constitutively active form of a MAPK kinase of WIPK/SIPK, and a mammalian pro-apoptotic factor Bax were used for cell death induction. Suppression of HSP90 and treatment with geldanamycin, a specific inhibitor of HSP90, compromised p50- but not NtMEK2DD- or Bax-mediated cell death accompanying the reduction of NtMEK2, WIPK and SIPK activation. In WIPK/SIPK-double knockdown plants, p50- and NtMEK2DD- but not Bax-mediated cell death was suppressed. All three types of cell death induced mitochondrial dysfunction, but they were similarly suppressed by Bcl-xL, which is a mammalian anti-apoptotic factor, and prevents mitochondrial dysfunction in plants as it does in animals in the cell death signal pathway. Taken together with the expression profile of hypersensitive reaction marker genes, it was indicated that the MAPK cascade functions downstream of HSP90 and transduces the cell death signal to mitochondria for N gene-dependent cell death. Furthermore, we found that WIPK and SIPK are functionally redundant in cell death signaling using WIPK/SIPK single or double knockdown plants.

Keywords: Heat shock protein 90; Mitochondria; Mitogen-activated protein kinase; Programmed cell death; Signal transduction; Transient expression

Journal Article.  6989 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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