Vacuolar H+-ATPase c protects glial cell death induced by sodium nitroprusside under glutathione-depleted condition

Abstract

We examined the role of the c subunit (ATP6L) of vacuolar H(+) -ATPase and its molecular mechanisms in glial cell death induced by sodium nitroprusside (SNP). ATP6L siRNA-transfected cells treated with SNP showed a significant increase in cytotoxicity under glutathione (GSH)-depleted conditions after pretreatment with buthionine sulfoximine, but reduction of ATP6L did not affect the regulation of lysosomal pH in analyses with lysosomal pH-dependent fluorescence probes. Photodegraded SNP and ferrous sulfate induced cytotoxicity with the same pattern as that of SNP, but SNAP and potassium cyanide did not show activity. Pretreatment of the transfected cells with deferoxamine (DFO) reduced ROS production and significantly inhibited the cytotoxicity, which indicates that primarily iron rather than nitric oxide or cyanide from SNP contributes to cell death. Involvement of apoptotic processes in the cells was not shown. Pretreatment with JNK or p38 chemical inhibitor significantly inhibited the cytotoxicity, and we also confirmed that the MAPKs were activated in the cells by immunoblot analysis. Significant increase of LC3-II conversion was observed in the cells, and the conversions were inhibited by cotransfection of the MAPK siRNAs and pretreatment with DFO. Introduction of Atg5 siRNA inhibited the cytotoxicity and inhibited the activation of MAPKs and the conversion of LC3. We finally confirmed autophagic cell death and involvement of MAPKs by observation of autophagic vacuoles via electron microscopy. These data suggest that ATP6L has a protective role against SNP-induced autophagic cell death via inhibition of JNK and p38 in GSH-depleted glial cells.

ATP6V0C Knockdown in Neuroblastoma Cells Alters Autophagy-Lysosome Pathway Function and Metabolism of Proteins that Accumulate in Neurodegenerative Disease

“…As ATP6V0C deficiency was shown previously to exacerbate stress-induced cell death [34]–[36] we next determined if knockdown of ATP6V0C was similarly toxic to differentiated SH-SY5Y neuroblastoma cells by investigating different markers of cytotoxicity (Fig. 6).…”

“…Knockdown of ATP6V0C has been shown recently to inhibit vesicular acidification and sensitize cells to stress-induced cell death [34]–[36], while ATP6V0C-deficient mice are embryonic lethal [37]. However, whether ATP6V0C itself is responsible for regulating ALP function, as well as the metabolism of substrates that accumulate in age-related neurodegenerative diseases has not been previously investigated.…”

Systems toxicology approaches enable mechanistic comparison of spontaneous and cigarette smoke-related lung tumor development in the A/J mouse model

“…In addition, the observed decrease in Psap gene expression could also explain the accumulation of glycosphingolipids, which may have ultimately resulted in lysosomal dysfunction (Schulze et al , 2009 ; Tatti et al , 2011 ). Moreover, suppression of Atp6v0c gene expression could point to the prevention of lysosomal leakage which releases breakdown products for reuse (Byun et al , 2011 ). Lysosomal leakage is also known to induce cell death, by apoptosis or necrosis, dependent on the extent of lysosomal damage (Yamashima & Oikawa, 2009 ).…”

Role of GS28 in sodium nitroprusside‐induced cell death in cervical carcinoma cells

“…In this study, we found that GS28 has an inductive role in SNP‐induced cell death by inhibiting autophagic processes via inhibition of ERK signaling. Our previous report is the first showing that SNP, as a ROS donor, is directly involved in autophagic processes . We demonstrated that SNP activates autophagic processes leading to cell death, which is protected by ATP6L, in glial cells .…”