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Two proteases with caspase‐3‐like activity, cathepsin B and proteasome, antagonistically control ER ‐stress‐induced programmed cell death in Arabidopsis
Author(s) -
Cai YaoMin,
Yu Jia,
Ge Yuan,
Mironov Aleksandr,
Gallois Patrick
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14676
Subject(s) - cathepsin b , unfolded protein response , downregulation and upregulation , cathepsin , microbiology and biotechnology , cathepsin a , cathepsin l , caspase , endoplasmic reticulum , cathepsin d , programmed cell death , proteases , proteasome , chemistry , biology , biochemistry , apoptosis , enzyme , gene
Summary Programmed cell death ( PCD ) induced by endoplasmic reticulum ( ER ) stress is implicated in various plant physiological processes, yet its mechanism is still elusive. An activation of caspase‐3‐like enzymatic activity was clearly demonstrated but the role of the two known plant proteases with caspase‐3‐like activity, cathepsin B and proteasome subunit PBA 1, remains to be established. Both genetic downregulation and chemical inhibition were used to investigate the function of cathepsin B and PBA 1 in ER ‐stress‐induced PCD ( ERSID ). Transcript level and activity labelling of cathepsin B were used to assess activation. To study tonoplast rupture, a plant PCD feature, both confocal and electronic microscopies were used. Cathepsin B downregulation reduced reactive oxygen species ( ROS ) accumulation and ERSID without affecting the induction of the unfolded protein response ( UPR ), but downregulation of PBA 1 increased UPR and ERSID . Tonoplast rupture was not altered in the cathepsin B mutant and cathepsin B activation was independent of vacuolar processing enzyme ( VPE ). VPE activity was independent of cathepsin B. ERSID is regulated positively by cathepsin B and negatively by PBA 1, revealing a complex picture behind caspase‐3‐like activity in plants. Cathepsin B may execute its function after tonoplast rupture and works in parallel with VPE .