TY - JOUR
T1 - Endosomes and lysosomes play distinct roles in sulfatide-induced neuroblastoma apoptosis
T2 - Potential mechanisms contributing to abnormal sulfatide metabolism in related neuronal diseases
AU - Zeng, Youchun
AU - Cheng, Hua
AU - Jiang, Xuntian
AU - Han, Xianlin
PY - 2008/2/15
Y1 - 2008/2/15
N2 - Alterations in sulfatide metabolism, trafficking and homoeostasis are present at the earliest clinically recognizable stages of Alzheimer's disease and are associated with metachromatic leukodystrophy. However, the role of sulfatide in these disease states remains unknown. In the present study, we investigated the sequelae of NB (neuroblastoma) cells upon sulfatide supplementation and the biochemical mechanisms contributing to the sulfatide-induced changes. By using shotgun lipidomics, we showed dramatic accumulations of sulfatide, ceramide and sphingosine in NB cells in a time- and dose-dependent manner. Further studies utilizing subcellular fractionation and shotgun lipidomics analyses demonstrated that most of the increased ceramide content was generated in the endosomal compartment, whereas sulfatides predominantly accumulated in lysosomes. In addition, we determined that the sulfatide-mediated increase in endosomal ceramide content mainly resulted from β-galactosidase activity, which directly hydrolyses sulfatide to ceramide without a prior desulfation step. Substantial cell apoptosis occurred in parallel with the accumulation of sulfatides and ceramides, as revealed by mitochondrial membrane depolarization, by phosphatidylserine translocation and by the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay. These findings were also demonstrated with primary neuron cultures. Collectively, our results demonstrate that abnormal sulfatide metabolism can induce cell apoptosis due to endosome-mediated ceramide generation and the accumulation of cytotoxic levels of sulfatides in lysosomes.
AB - Alterations in sulfatide metabolism, trafficking and homoeostasis are present at the earliest clinically recognizable stages of Alzheimer's disease and are associated with metachromatic leukodystrophy. However, the role of sulfatide in these disease states remains unknown. In the present study, we investigated the sequelae of NB (neuroblastoma) cells upon sulfatide supplementation and the biochemical mechanisms contributing to the sulfatide-induced changes. By using shotgun lipidomics, we showed dramatic accumulations of sulfatide, ceramide and sphingosine in NB cells in a time- and dose-dependent manner. Further studies utilizing subcellular fractionation and shotgun lipidomics analyses demonstrated that most of the increased ceramide content was generated in the endosomal compartment, whereas sulfatides predominantly accumulated in lysosomes. In addition, we determined that the sulfatide-mediated increase in endosomal ceramide content mainly resulted from β-galactosidase activity, which directly hydrolyses sulfatide to ceramide without a prior desulfation step. Substantial cell apoptosis occurred in parallel with the accumulation of sulfatides and ceramides, as revealed by mitochondrial membrane depolarization, by phosphatidylserine translocation and by the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay. These findings were also demonstrated with primary neuron cultures. Collectively, our results demonstrate that abnormal sulfatide metabolism can induce cell apoptosis due to endosome-mediated ceramide generation and the accumulation of cytotoxic levels of sulfatides in lysosomes.
KW - Alzheimer's disease (AD)
KW - Ceramide
KW - Electrospray ionization MS (ESI-MS)
KW - Metachromatic leukodystrophy
KW - Shotgun lipidomics
KW - Sulfatide
UR - http://www.scopus.com/inward/record.url?scp=39749106531&partnerID=8YFLogxK
U2 - 10.1042/BJ20070976
DO - 10.1042/BJ20070976
M3 - Article
C2 - 17939778
AN - SCOPUS:39749106531
VL - 410
SP - 81
EP - 92
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
IS - 1
ER -