• YAKHAK HOEJI
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• v.43 no.1
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• pp.85-90
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• 1999

FTY720, a novel immunosuppressant, elevated the level of endogenous sphingoid bases in a dose-dependent manner within 3 hr in $LLC-PK_1$ cells. The relative molar ratio of sphingoid bases expressed as sphingosine/sphinganine (SPN/SPA), a biomarker of altered sphingolipid biosynthesis, in $10{\;}{\mu}M$ of FTY720 showed tow-fold increase as compared with the one in control culture. FTY720 under the serum-free medium condition increased only cytosolic free sphingosine concentration, not sphinganine concentration in a time-dependent manner over the 8 hr incubation under the same condition as in serum free cultures, the SPN/SPA ratio began to fluctuate and the number of floating cells as an indicator of cytotoxicity was increased 8 hr after the addition of FTY720 to cultured cells. These results suggest that the process of FTY720-induced cell death in $LLC-PK_1$ cells.

• Journal of Nutrition and Health
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• v.45 no.2
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• pp.113-120
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• 2012

In our previous studies, dietary supplements of silk protein, sericin, and fibroin, were beneficial for improving epidermal levels of ceramides, which are the major lipids for maintaining the epidermal barrier. In this study, we investigated the dietary effects of silk protein on epidermal levels of free sphingoid bases and their phosphates such as $C_{18}$ sphingosine (So), $C_{18}$ sphinganine (Sa), $C_{18}$ sphingosine-1-phosphate (S1P), and $C_{18}$ sphinganine-1-phosphate (Sa1P), which are either synthetic substrate or degradative metabolites of ceramides. Forty-five male NC/Nga mice, an animal model of atopic dermatitis (AD), were divided into three groups: group CA was an atopic control and fed a control diet, group S was fed a 1% sericin diet, and group F was fed a 1% fibroin diet. Fifteen male BALB/c mice served as group C (control group) and were fed the control diet. All mice were fed with diets and water $ad$ $libitum$ for 10 weeks. Sa in group CA was lower than that in group C, but So in group CA was similar to that in group C. So and Sa were higher in groups S and F than those in group CA; So level was even higher than that in group C, and Sa level was similar to that of group C. The So/Sa ratio in group CA, which is reported to increase in AD, was significantly higher than that of group C. The So/Sa ratio was lower in groups S and F than that in group CA, and decreased further in group F. However, S1P and Sa1P in groups S and F were similar to those in group CA. Taken together, we demonstrated that silk protein, sericin and fibroin dietary supplements, increased So and Sa levels, and decreased the So/Sa ratio.