After blocking, the PVDF membranes were incubated overnight at 4[degrees]C with IRE1[alpha] (1:800), p-IRE1[alpha] (1:600), caspase 12
(1:800), C/EBP homologous protein (CHOP, 1:1000), and 78 kDa glucose-regulated protein (GRP78, 1:1000), all rabbit antibodies (CST, USA).
In the condition of ERS, the overexpression of PERK will phosphorylate eIF2[alpha], and then the p-eIF2[alpha] will transcribe some transcription factors, such as activating transcription factor 4 (ATF-4), C/EBP homologous protein (CHOP), and caspase 12 , which affect the apoptosis of cells or tissues through PERK-dependent pathway.
Results from western blot analysis demonstrate that compared with control group, CHOP, bax, caspase 3, and caspase 12 protein expressions were significantly increased in MA groups, which were markedly decreased after administration of TBHQ (Figure 5(a)).
This chronic stimulation caused lasting ERS and further induced apoptosis by the increase in CHOP, bax, caspase 3, caspase 12 and decrease in bcl-2.
(a) Apoptotic cytokines CHOP, bax, caspase 12 and caspase 3 expressed in different groups by western blot; (b) immunofluorescence assay for bax and bcl-2 in different groups (x400).
Caspase 12, C/EBP homologous protein (CHOP), and cJun N-terminal kinase (JNK) are three primary molecules that play a critical role in ER stress-induced apoptosis .
Antibodies against calpain 1, caspase 12, caspase 3, [beta]-tubulin, and goat anti rabbit IgG (H+L) secondary antibody were obtained from Abcam (Cambridge, UK).
Calpain 1, caspase 12, and caspase 3 proteins were separated via 10% SDS-PAGE.
These results confirm that calpain cleaves caspase 12 and promotes caspase 12 activation and that the activation of caspase 12 results in the activation of caspase 3.
Recently, a mechanism of signaling for programmed cell death was described which requires the activation of caspase 12
. In mice, caspase 12
appears to be localized to endoplasmic reticulum (ER), and is activated in response to stimuli by which ER became stressed and release the calcium stored (Nakagawa et al., 2000).
This novel observation associated with the benzene toxicity mechanism together with the downmodulation of caspase 12
was similarly addressed using WT and p53-KO mice in the study of the mechanism of chronic obstructive urinary disturbances (Choi et al.