Mitochondria-associated hexokinases play a role in the control of programmed cell death in Nicotiana benthamiana

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Title
Mitochondria-associated hexokinases play a role in the control of programmed cell death in Nicotiana benthamiana
Author(s)
Moonil Kim; J H Lim; C S Ahn; K Park; G T Kim; W T Kim; H S Pai
Bibliographic Citation
Plant Cell, vol. 18, no. 9, pp. 2341-2355
Publication Year
2006
Abstract
Recent findings suggest a pivotal role for mitochondria-associated hexokinase in the regulation of apoptosis in animal cells. In this study, virus-induced gene silencing (VIGS) of a hexokinase-encoding Hxk1 caused necrotic lesions on leaves, abnormal leaf morphology, and retarded plant growth in Nicotiana benthamiana. Hxk1 was associated with the mitochondria, and this association required the N-terminal membrane anchor. VIGS of Hxk1 reduced the cellular glucose-phosphorylating activity to ∼31% of control levels without changing the fructose-phosphorylating activity and did not alter hexose phosphate content severely. The affected cells showed programmed cell death (PCD) morphological markers, including nuclear condensation and DNA fragmentation. Similar to animal cell apoptosis, cytochrome c was released into the cytosol and caspase-9- and caspase-3-like proteolytic activities were strongly induced. Furthermore, based on flow cytometry, Arabidopsis thaliana plants overexpressing Arabidopsis HXK1 and HXK2, both of which are predominantly associated with mitochondria, exhibited enhanced resistance to H 2O2- and α-picolinic acid-induced PCD. Finally, the addition of recombinant Hxk1 to mitochondria-enriched fractions prevented H 2O2/clotrimazole-induced cytochrome c release and loss of mitochondria! membrane potential. Together, these results show that hexokinase critically regulates the execution of PCD in plant cells, suggesting a link between glucose metabolism and apoptosis.
ISSN
1040-4651
Publisher
Amer Soc Plant Biologists
DOI
http://dx.doi.org/10.1105/tpc.106.041509
Type
Article
Appears in Collections:
Division of Biomaterials Research > Bionanotechnology Research Center > 1. Journal Articles
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