Yasuyuki Igarashi

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The ganglioside patterns have been shown to dramatically change during cell proliferation and differentiation and in certain cell-cycle phases, brain development, and cancer malignancy. To investigate the significance of the ganglioside GM3 in cancer malignancy, we established GM3-reconstituted cells by transfecting the cDNA of GM3 synthase into a(More)
Platelets are known to store a large amount of the bioactive lipid molecule sphingosine 1-phosphate (S1P) and to release it into the plasma in a stimuli-dependent manner. Erythrocytes can also release S1P, independently from any stimuli. We measured the S1P and sphingosine (Sph) levels in erythrocytes by HPLC and found that the contribution of erythrocyte(More)
Sphingosine 1-phosphate (S1P) is accumulated in platelets and released on stimulation by thrombin or Ca(2+). Thrombin-stimulated S1P release was inhibited by staurosporin, whereas Ca(2+)-stimulated release was not. When the platelet plasma membrane was permeabilized with streptolysin O (SLO), S1P leaked out with cytosol markers, whereas granular markers(More)
Elevated amyloid-β peptide (Aβ) in brain contributes to Alzheimer's disease (AD) pathogenesis. We demonstrated the presence of exosome-associated Aβ in the cerebrospinal fluid (CSF) of cynomolgus monkeys and APP transgenic mice. The levels of exosome-associated Aβ notably decreased in the CSF of aging animals. We also determined that neuronal exosomes, but(More)
The serum-borne lysophospholipid mediators sphingosine 1-phosphate (Sph-1-P) and lysophosphatidic acid (LPA) have been shown to be released from activated platelets and to act on endothelial cells. In this study, we employed the repeated lipid extraction (under alkaline and acidic conditions), capable of detecting Sph-1-P, LPA, and possibly structurally(More)
Activation of the PDGF receptor on human arterial smooth muscle cells (SMC) induces migration and proliferation via separable signal transduction pathways. Sphingosine-1-phosphate (Sph-1-P) can be formed following PDGF receptor activation and therefore may be implicated in PDGF-receptor signal transduction. Here we show that Sph-1-P does not significantly(More)
The present studies were undertaken to characterize the potential role of sphingosine in the regulation of apoptosis in III-t.O promyelocytic leukemia cells. A 6-h exposure of HL-60 cells to sphingosine or its meth ylated derivative, /VVV-dimethylsphingosine, caused internucleosomal DNA fragmentation and stereotypical morphological changes character istic(More)
Biological membranes consist of lipid bilayers. The lipid compositions between the two leaflets of the plasma membrane differ, generating lipid asymmetry. Maintenance of proper lipid asymmetry is physiologically quite important, and its collapse induces several cellular responses including apoptosis and platelet coagulation. Thus, a change in lipid(More)
The discovery of ceramide kinase (CerK), which phosphorylates ceramide (Cer) to ceramide 1-phisphate (C1P), established a new pathway for Cer metabolism. Among mouse tissues, brain contains the highest CerK activity. In this study, we found that CerK is highly expressed in cerebellar Purkinje cells. Since Purkinje cells are important for motor-related(More)
BACKGROUND Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that regulate lipid and glucose metabolism. PPARα is highly expressed in the liver and controls genes involved in lipid catabolism. We previously reported that synthetic sphingolipid analogs, part of which contains shorter-length fatty acid chains than(More)