TY - JOUR
T1 - Induction of apoptosis and necroptosis by 24(S)-hydroxycholesterol is dependent on activity of acyl-CoA:cholesterol acyltransferase 1
AU - Yamanaka, K.
AU - Urano, Y.
AU - Takabe, W.
AU - Saito, Y.
AU - Noguchi, N.
N1 - Funding Information:
Acknowledgements. We thank Dr. Yoko Ogawa Akazawa (National Institute of Advanced Industrial Science and Technology, Osaka, Japan) for supporting GC–MS analysis. We thank Dr. Paul Huang in Dr. Ta-Yuan Chang’s lab (Dartmouth Medical School) for providing the ACAT1 siRNA sequence used in this study. We also thank Dr. Ta-Yuan Chang and Kowa Co. Ltd (Tokyo, Japan) for providing valuable reagents. This work was supported in part by the KAKENHI Grant-in-Aid for Young Scientists (B) 23700428, 25830041 to YU and for JSPS fellows 243567 to KY from JSPS and the MEXT-Supported Program for the Strategic Research Foundation at Private Universities in Japan for the years 2012–2016.
PY - 2014/1
Y1 - 2014/1
N2 - 24(S)-hydroxycholesterol (24S-OHC), which is enzymatically produced in the brain, has an important role in maintaining brain cholesterol homeostasis. We have previously reported that 24S-OHC induces necroptosis in human neuroblastoma SH-SY5Y cells. In the present study, we investigated the mechanisms by which 24S-OHC-induced cell death occurs. We found that lipid droplets formed at the early stages in the treatment of SH-SY5Y cells with 24S-OHC. These lipid droplets could be almost completely eliminated by treatment with a specific inhibitor or by siRNA knockdown of acyl-CoA:cholesterol acyltransferase 1 (ACAT1). In association with disappearance of lipid droplets, cell viability was recovered by treatment with the inhibitor or siRNA for ACAT1. Using gas chromatography-mass spectrometry, we confirmed that 24S-OHC-treated cells exhibited accumulation of 24S-OHC esters but not of cholesteryl esters and confirmed that accumulation of 24S-OHC esters was reduced when ACAT1 was inhibited. 24S-OHC induced apoptosis in T-lymphoma Jurkat cells, which endogenously expressed caspase-8, but did not induce apoptosis in SH-SY5Y cells, which expressed no caspase-8. In Jurkat cells treated with the pan-caspase inhibitor ZVAD and in caspase-8-deficient Jurkat cells, 24S-OHC was found to induce caspase-independent cell death, and this was partially but significantly inhibited by Necrostatin-1. Similarly, knockdown of receptor-interacting protein kinase 3, which is one of the essential kinases for necroptosis, significantly suppressed 24S-OHC-induced cell death in Jurkat cells treated with ZVAD. These results suggest that 24S-OHC can induce apoptosis or necroptosis, which of the two is induced being determined by caspase activity. Regardless of the presence or absence of ZVAD, 24S-OHC treatment induced the formation of lipid droplets and cell death in Jurkat cells, and this was suppressed by treatment with ACAT1 inhibitor. Collectively, these results suggest that it is ACAT1-catalyzed 24S-OHC esterification and the resulting lipid droplet formation that is the initial key event which is responsible for 24S-OHC-induced cell death.
AB - 24(S)-hydroxycholesterol (24S-OHC), which is enzymatically produced in the brain, has an important role in maintaining brain cholesterol homeostasis. We have previously reported that 24S-OHC induces necroptosis in human neuroblastoma SH-SY5Y cells. In the present study, we investigated the mechanisms by which 24S-OHC-induced cell death occurs. We found that lipid droplets formed at the early stages in the treatment of SH-SY5Y cells with 24S-OHC. These lipid droplets could be almost completely eliminated by treatment with a specific inhibitor or by siRNA knockdown of acyl-CoA:cholesterol acyltransferase 1 (ACAT1). In association with disappearance of lipid droplets, cell viability was recovered by treatment with the inhibitor or siRNA for ACAT1. Using gas chromatography-mass spectrometry, we confirmed that 24S-OHC-treated cells exhibited accumulation of 24S-OHC esters but not of cholesteryl esters and confirmed that accumulation of 24S-OHC esters was reduced when ACAT1 was inhibited. 24S-OHC induced apoptosis in T-lymphoma Jurkat cells, which endogenously expressed caspase-8, but did not induce apoptosis in SH-SY5Y cells, which expressed no caspase-8. In Jurkat cells treated with the pan-caspase inhibitor ZVAD and in caspase-8-deficient Jurkat cells, 24S-OHC was found to induce caspase-independent cell death, and this was partially but significantly inhibited by Necrostatin-1. Similarly, knockdown of receptor-interacting protein kinase 3, which is one of the essential kinases for necroptosis, significantly suppressed 24S-OHC-induced cell death in Jurkat cells treated with ZVAD. These results suggest that 24S-OHC can induce apoptosis or necroptosis, which of the two is induced being determined by caspase activity. Regardless of the presence or absence of ZVAD, 24S-OHC treatment induced the formation of lipid droplets and cell death in Jurkat cells, and this was suppressed by treatment with ACAT1 inhibitor. Collectively, these results suggest that it is ACAT1-catalyzed 24S-OHC esterification and the resulting lipid droplet formation that is the initial key event which is responsible for 24S-OHC-induced cell death.
KW - 24S-hydroxycholesterol
KW - Acyl-CoA:cholesterol acyltransferase
KW - Apoptosis
KW - Lipid droplets
KW - Necroptosis
UR - http://www.scopus.com/inward/record.url?scp=84891771031&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84891771031&partnerID=8YFLogxK
U2 - 10.1038/cddis.2013.524
DO - 10.1038/cddis.2013.524
M3 - Article
C2 - 24407243
AN - SCOPUS:84891771031
SN - 2041-4889
VL - 5
JO - Cell Death and Disease
JF - Cell Death and Disease
IS - 1
M1 - e990
ER -
