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

• Proceedings of the PSK Conference
• /
• 2003.04a
• /
• pp.228.1-228.1
• /
• 2003

Sphingolipid metabolites have been implicated as an important component of cell signalling, such as cell proliferation, differentiation and apoptosis. But the roles of phytoceramide and its deraivatives are very poorly understood. even though they are abundant in plants, yeasts and animals including humans. We investigated the effects of N-acetyl-C2-phytosphingosine(NAPS) and the analogue of N.N-dimethylsphingosine(DMS), N,N-dimethylphytosphytosphingosine(DMPS), on cell growth inhibition and apoptosis. (omitted)

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.110.1-110.1
• /
• 2003

Fumonisins are specific inhibitors of ceramide synthase in sphingolipid metabolism. Sphingolipids are biologically active lipid mediators in cellular physiology and involved in cell signaling, growth, transformation, angiogenesis and differentiation. The objective of this study was to determine the effect of fumonisin B1 on $Na^+, \;K^+$-pump activity when fumonisin B1 was exposed to LLC-PK1 cells. Fumonisin B1 elevated free sphingoid bases and their 1-phosphates, while total complex sphingolipids were depleted at 20$\mu$M fumonisin B1 during the 3 day exposure. (omitted)

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.216.2-216.2
• /
• 2003

Sphingolipids has been known to induce apoptosis, cell proliferation, differentiation and migration in a variety of cell types. Recently, its phosphate form was suggested that they may act both as an agonist ligand to SlPRs and a second messenger in intracellular action. Phytosphingosine(PHS) is not easily detected due to trace component of cellular lipids in mammalian and human tissues while this is a major sphingolipid in yeast and plants. We therefore developed highly sensitive and reproducible analytical method for PHS and its phosphate by oxalic acid bis(2,4,6-tri-chlorophenyl) ester(TCPO)-hydrogen peroxide(H$_2$O$_2$) chemiluminescence. (omitted)

• Korean Journal of Veterinary Research
• /
• v.35 no.2
• /
• pp.405-416
• /
• 1995

FBs, secondary metabolites of several species of Fusaria, especially Fusarium moniliforme and F proliferatum, are commonly contaminated in com and other food grains throughout the world. Only recently identified, these mycotoxins have been associated field outbreaks of ELEM in horses and PPE in pigs. Currently, naturally or experimentally induced FB toxicosis has been studied in poultry, ruminants and rabbits. Poultry fed FB showed decreased growth rate, performance, and immune competence, as well as embryopathic, and embryocidal effects, and ricktes. Ruminants seem to be relatively less susceptible to FBs than other doestic animal. FB toxicosis reveals that liver is a target organ in all species, although other organs are affected in a species specific manner. Recently, the main target organs for $FB_1$ toxicity in rabbits was shown to be the kidney. Even low concentrations of FBs are likely to be a problem for animal health. A current study being conducted showed that feed containing low level of $FB_1$ reduces the ability of pulmonary intravascular macrophages in pig to clear blood-borne particles which would increase the susceptibility of animals to bacterial disease. The mechanism of FB toxicity remains unknown, but may be related to altered sphingolipid biosynthesis by inhibiting sphinganine N-acyltransferase. Elevations of serum and tissue SA:SO ratio have been observed in horse, pig, chicken, turkey, and rabbit, which could could serve as in effective biomarker for consumption of FB-containing feeds. There is limited information detailing dose-effect relationships either from field cases or in the laboratory. More research on the factors, including the prevalence and tolerance levels of FBs in feedstuffs that cause domestic animal disease associated with FBs, is urgently needed.

• Archives of Pharmacal Research
• /
• v.24 no.2
• /
• pp.136-143
• /
• 2001

Fumonisins are specific inhibitors of ceramide synthase in sphingolipid metabolism. An alteration in sphingolipid metabolism as a result of fumonisin exposure is related to cell death (Yoo et al., 1992). The objective of this study was to investigate whether elevated free sphinganine levels are related to the sensitivity of cultured cells to fumonisin exposure. Fumonisin $B_1$ elevated the intracellular free sphinganine concentraions in both LLC-$PK_1$ and Chinese hamster ovary (CHO) cells. However, CHO cells are resistant to fumonisin cytotoxicity at 50${u}m$, while LLC-$PK_1$ cells are sensitive at concentrations greater than 357M. The intracellular concentration of free sphinganine in LLC-$PK_1$ cells treated at 50${u}m$ fumonisin $B_1$ for 72 h was approximately 1450 pmol/mg protein relative to the 37 pmol observed in the control culture. Under the same conditions, the population of apoptotic cells in the 50${u}m$ fumonisin $B_1$-treated culture was approximately 37% of the total compared to 12% in the control. The caspase III-like activity after 72 h in the 50${\mu}$M fumonisin $B_1$-exposed culture Increased to approximately 50 $pmol/mg$ protein/hr compared to 6 $pmol/mg$ protein/hr in the control. L-cycloserine, a serine palmitoyltransferase inhibitory reduced the fumonisin $B_1$-stimulated caspase III-like activity down to the control level. Under the same culture conditions, the intracellular concentration of free sphinganine after-cycloserine plus fumonisin $B_1$ treatment was 140 pmol/mg protein compared to 1450 $pmol/mg$ protein in fumonisin $B_1$ alone. The intracellular concentration of free sphinganine in CHO cells treated with 50${u}m$ fumonisin $B_1$ for 72 h was al)proximately 460 pmol/mg protein, indicating that the mass amount of elevated free sphinganine in the CHO cells was about 32% of that in LLC-$PK_1$ cells. Adding exogenous sphinganine to the CHO cells along with 50${u}m$ fumonisin $B_1$ treatment for 72 h caused both necrosis and apoptosis. In conclusion, the elevated endogenous sphinganine acts as a contributing factor to the fumonisin-induced cell death.

• Biomolecules & Therapeutics
• /
• v.30 no.6
• /
• pp.553-561
• /
• 2022

Chronic myeloid leukemia (CML) is a slowly progressing hematopoietic cell disorder. Sphingosine kinase 1 (SPHK1) plays established roles in tumor initiation, progression, and chemotherapy resistance in a wide range of cancers, including leukemia. However, small-molecule inhibitors targeting SPHK1 in CML still need to be developed. This study revealed the role of SPHK1 in CML and investigated the potential anti-leukemic activity of hirsuteine (HST), an indole alkaloid obtained from the oriental plant Uncaria rhynchophylla, in CML cells. These results suggest that SPHK1 is highly expressed in CML cells and that overexpression of SPHK1 represents poor clinical outcomes in CML patients. HST exposure led to G2/M phase arrest, cellular apoptosis, and downregulation of Cyclin B1 and CDC2 and cleavage of Caspase 3 and PARP in CML cells. HST shifted sphingolipid rheostat from sphingosine 1-phosphate (S1P) towards the ceramide coupled with a marked inhibition of SPHK1. Mechanistically, HST significantly blocked SPHK1/S1P/S1PR1 and BCR-ABL/PI3K/Akt pathways. In addition, HST can be docked with residues of SPHK1 and shifts the SPHK1 melting curve, indicating the potential protein-ligand interactions between SPHK1 and HST in both CML cells. SPHK1 overexpression impaired apoptosis and proliferation of CML cells induced by HST alone. These results suggest that HST, which may serve as a novel and specific SPHK1 inhibitor, exerts anti-leukemic activity by inhibiting the SPHK1/S1P/S1PR1 and BCR-ABL/PI3K/Akt pathways in CML cells, thus conferring HST as a promising anti-leukemic drug for CML therapy in the future.

• Molecules and Cells
• /
• v.38 no.6
• /
• pp.482-495
• /
• 2015

Sphingolipids such as ceramide, sphingosine-1-phosphate and sphingomyelin have been emerging as bioactive lipids since ceramide was reported to play a role in human leukemia HL-60 cell differentiation and death. Recently, it is well-known that ceramide acts as an inducer of cell death, that sphingomyelin works as a regulator for microdomain function of the cell membrane, and that sphingosine-1-phosphate plays a role in cell survival/proliferation. The lipids are metabolized by the specific enzymes, and each metabolite could be again returned to the original form by the reverse action of the different enzyme or after a long journey of many metabolizing/synthesizing pathways. In addition, the metabolites may serve as reciprocal biomodulators like the rheostat between ceramide and sphingosine-1-phosphate. Therefore, the change of lipid amount in the cells, the subcellular localization and the downstream signal in a specific subcellular organelle should be clarified to understand the pathobiological significance of sphingolipids when extracellular stimulation induces a diverse of cell functions such as cell death, proliferation and migration. In this review, we focus on how sphingolipids and their metabolizing enzymes cooperatively exert their function in proliferation, migration, autophagy and death of hematopoetic cells, and discuss the way developing a novel therapeutic device through the regulation of sphingolipids for effectively inhibiting cell proliferation and inducing cell death in hematological malignancies such as leukemia, malignant lymphoma and multiple myeloma.

• BMB Reports
• /
• v.48 no.12
• /
• pp.691-695
• /
• 2015

We report that phytosphingosine, a sphingolipid found in many organisms and implicated in cellular signaling, promotes megakaryocytic differentiation of myeloid leukemia cells. Specifically, phytosphingosine induced several hallmark changes associated with megakaryopoiesis from K562 and HEL cells including cell cycle arrest, cell size increase and polyploidization. We also confirmed that cell type specific markers of megakaryocytes, CD41a and CD42b are induced by phytosphingosine. Phospholipids with highly similar structures were unable to induce similar changes, indicating that the activity of phytosphingosine is highly specific. Although phytosphingosine is known to activate p38 mitogen-activated protein kinase (MAPK)-mediated apoptosis, the signaling mechanisms involved in megakaryopoiesis appear to be distinct. In sum, we present another model for dissecting molecular details of megakaryocytic differentiation which in large part remains obscure.

• The Plant Pathology Journal
• /
• v.31 no.1
• /
• pp.1-11
• /
• 2015

Antimicrobial cyclic peptides derived from microbes bind stably with target sites, have a tolerance to hydrolysis by proteases, and a favorable degradability under field conditions, which make them an attractive proposition for use as agricultural fungicides. Antimicrobial cyclic peptides are classified according to the types of bonds within the ring structure; homodetic, heterodetic, and complex cyclic peptides, which in turn reflect diverse physicochemical features. Most antimicrobial cyclic peptides affect the integrity of the cell envelope. This is achieved through direct interaction with the cell membrane or disturbance of the cell wall and membrane component biosynthesis such as chitin, glucan, and sphingolipid. These are specific and selective targets providing reliable activity and safety for non-target organisms. Synthetic cyclic peptides produced through combinatorial chemistry offer an alternative approach to develop antimicrobials for agricultural uses. Those synthesized so far have been studied for antibacterial activity, however, the recent advancements in powerful technologies now promise to provide novel antimicrobial cyclic peptides that are yet to be discovered from natural resources.