Activation of the programmed cell death pathway by inhibition of proteasome function in plants

Moonil Kim, Joon Woo Ahn, Un Ho Jin, Doil Choi, Kyung Hee Paek, Hyun Sook Pai

Research output: Contribution to journalArticlepeer-review

189 Citations (Scopus)


Proteasomes constitute the major machinery to degrade or process proteins by ATP/ubiquitin-mediated proteolysis. Recent findings suggest a pivotal role of the ubiquitin/proteasome pathway in the regulation of apoptosis in animal cells. Here we show that virus-induced gene silencing of two different subunits of the 26 S proteasome, the α6 subunit of the 20 S proteasome and RPN9 subunit of 19 S regulatory complex, both activated the programmed cell death (PCD) program, accompanied by reduced proteasome activity and accumulation of polyubiquitinated proteins. These results demonstrate that disruption of proteasome function leads to PCD in plant cells. The affected cells showed morphological markers of PCD, including nuclear condensation and DNA fragmentation, accompanied by the 10-fold higher production of reactive oxygen species and increased ion leakage for 3-fold. Similar to apoptosis in animal system, mitochondrial membrane potential was decreased, cytochrome c released from mitochondria to cytosol, and caspase 9- and caspase 3-like proteolytic activities detected in the cells. Interestingly, this proteasome-mediated PCD stimulated the expression of only a subset of transcripts that are highly induced during pathogen-mediated hypersensitive response cell death, indicating that the two PCD pathways are differentially regulated. Taken together, these results provide the first direct evidence that proteasomes play a role in the regulatory program of PCD in plants. Controlled inhibition of proteasome activities may be involved in developmentally or environmentally activated plant cell death programs.

Original languageEnglish
Pages (from-to)19406-19415
Number of pages10
JournalJournal of Biological Chemistry
Issue number21
Publication statusPublished - 2003 May 23

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Activation of the programmed cell death pathway by inhibition of proteasome function in plants'. Together they form a unique fingerprint.

Cite this