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THE Spodoptera frugiperda EFFECTOR CASPASE SF ‐CASPASE‐1 BECOMES UNSTABLE FOLLOWING ITS ACTIVATION
Author(s) -
Ying Zhongfu,
Li Ao,
Lu Zhaodan,
Wu Chunfeng,
Yin Hanqi,
Yuan Meijin,
Pang Yi
Publication year - 2013
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.21106
Subject(s) - lactacystin , caspase , biology , protein subunit , microbiology and biotechnology , sf9 , proteasome , spodoptera , caspase 3 , effector , biochemistry , apoptosis , recombinant dna , proteasome inhibitor , programmed cell death , gene
S f‐caspase‐1 is the principal effector caspase in S podoptera frugiperda cells. Like the caspases in other organisms, S f‐caspase‐1 is processed by upstream caspases to form an active heterotetramer composed of the p19 and p12 subunits. The regulation of active caspases is crucial for cellular viability. In mammal cells, the subunits and the active form of caspase‐3 were rapidly degraded relative to its proenzyme form. In the present study, the S . frugiperda S f9 cells were transiently transfected with plasmids encoding different fragments of S f‐caspase‐1: the pro‐ S f‐caspase‐1 (p37), a prodomain deleted fragment (p31), a fragment containing the large subunit and the prodomain (p25), the large subunit (p19), and the small subunit (p12). Flow cytometry and W estern blot analysis revealed that p12, p19, and p25 were unstable in the transfected cells, in contrast to p37 and p31. Lactacystin, a proteasome inhibitor, increased the accumulation of the p19 and p12 subunits, suggesting that the degradation is performed by the ubiquitin‐proteasome system. During the activation, the S f‐caspase‐1 produces an intermediate form and then undergoes proteolytic processing to form active S f‐caspase‐1. We found that both the active and the intermediate form were unstable, indicating that once activated or during its activation, the S f‐caspase‐1 was unstable.