• BMB Reports
• /
• v.52 no.2
• /
• pp.111-112
• /
• 2019

Although many studies have reported that the breakdown of the blood-brain barrier (BBB) represents one of the major pathological changes in aging, the mechanism underlying this process remains relatively unexplored. In this study, we described that acid sphingomyelinase (ASM) derived from endothelial cells plays a critical role in BBB disruption in aging. ASM levels were elevated in the brain endothelium and plasma of aged humans and mice, resulting in BBB leakage through an increase in caveolae-mediated transcytosis. Moreover, ASM caused damage to the caveolae-cytoskeleton via protein phosphatase 1-mediated ezrin/radixin/moesin dephosphorylation in primary mouse brain endothelial cells. Mice overexpressing brain endothelial cell-specific ASM exhibited acceleration of BBB impairment and neuronal dysfunction. However, genetic inhibition and endothelial specific knock-down of ASM in mice improved BBB disruption and neurocognitive impairment during aging. Results of this study revealed a novel role of ASM in the regulation of BBB integrity and neuronal function in aging, thus highlighting the potential of ASM as a new therapeutic target for anti-aging.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.5
• /
• pp.655-660
• /
• 1999

Sphingomyelinase (SMase EC:3.l.4.l2) has been suggested to play important roles in the cell cycle, differentiation, apoptosis, inflammation, and the regulation of eukaryotic stress responses. SMase inhibitors may be a powerful tool to elucidate and regulate these cellular responses in which SMase involves. We first isolated an SMase inhibitor, named sphinin, from a strain of soil actinomycetes, F50970. Sphinin inhibited Mg/sup 2+/ -dependent neutral SMase from chicken embryo at 1.2 ㎍/㎖ of IC/sub 50/ Sphinin also inhibited acidic SMase, but it had no inhibitory activity on PI-PLC and PC-PLC, suggesting that sphinin is a specific inhibitor of SMase. The strain F50970 was identified as a Streptomyces sp. by its spiral spore chain, LL-diaminopimelic acid, menaquinone patterns of MK-9 (H'6) and MK-9 (H'8), FA-2c type of fatty acid pattern, and other morphological, physiological, and cultural characteristics.

• BMB Reports
• /
• v.55 no.12
• /
• pp.621-626
• /
• 2022

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by the degeneration of motor neurons in the spinal cord. Main symptoms are manifested as weakness, muscle loss, and muscle atrophy. Some studies have reported that alterations in sphingolipid metabolism may be intimately related to neurodegenerative diseases, including ALS. Acid sphingomyelinase (ASM), a sphingolipid-metabolizing enzyme, is considered an important mediator of neurodegenerative diseases. Herein, we show that ASM activity increases in samples from patients with ALS and in a mouse model. Moreover, genetic inhibition of ASM improves motor function impairment and spinal neuronal loss in an ALS mouse model. Therefore, these results suggest the role of ASM as a potentially effective target and ASM inhibition may be a possible therapeutic approach for ALS.

• Korean Journal of Exercise Nutrition
• /
• v.23 no.2
• /
• pp.1-6
• /
• 2019

[Purpose] Strenuous exercise often induces skeletal muscle damage, which results in impaired performance. Sphingolipid metabolism contributes to various cellular processes, including apoptosis, stress response, and inflammation. However, the relationship between exercise-induced muscle damage and ceramide (a key component of sphingolipid metabolism), is rarely studied. The present study aimed to explore the regulatory role of sphingolipid metabolism in exercise-induced muscle damage. [Methods] Mice were subjected to strenuous exercise by treadmill running with gradual increase in intensity. The blood and gastrocnemius muscles (white and red portion) were collected immediately after and 24 h post exercise. For 3 days, imipramine was intraperitoneally injected 1 h prior to treadmill running. [Results] Interleukin 6 (IL-6) and serum creatine kinase (CK) levels were enhanced immediately after and 24 h post exercise (relative to those of resting), respectively. Acidic sphingomyelinase (A-SMase) protein expression in gastrocnemius muscles was significantly augmented by exercise, unlike, serine palmitoyltransferase-1 (SPT-1) and neutral sphingomyelinase (N-SMase) expressions. Furthermore, imipramine (a selective A-SMase inhibitor) treatment reduced the exercise-induced CK and IL-6 elevations, along with a decrease in cleaved caspase-3 (Cas-3) of gastrocnemius muscles. [Conclusion] We found the crucial role of A-SMase in exercise-induced muscle damage.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2002.07a
• /
• pp.249-249
• /
• 2002

• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.6
• /
• pp.281-286
• /
• 2002

To understand the cytotoxic mechanism of $MPP^+,$ we examined the involvement of ceramide in $MPP^+-induced$ cytotoxicity to human neuroblastoma SH-SY5Y cells. When SH-SY5Y cells were exposed to $MPP^+,\;MPP^+$ induced dose-dependent cytotoxicity accompanied by 2-fold elevation of intracellular ceramide levels in SH-SY5Y cells. Three methods were used to test the hypothesis that the elevated intracellular ceramide is related to $MPP^+-induced$ cytotoxicity: $C_2-ceramide$ was directly applied to cells, sphingomyelinase (SMase) was exogenously added, and oleoylethanolamine (OE) was used to inhibit degradation of ceramide. Furthermore, inhibition of ceramide-activated protein phosphatase (CAPP), the effector of ceramide, using okadaic acid (OA) attenuated cell death but treatment of fumonisin $B_1,$ the ceramide synthase inhibitor, did not alter the cytotoxic effect of $MPP^+.$ Based on these, we suggest that the elevation of intracellular ceramide is one of the important mediators in $MPP^+-induced$ cell death.

• The Journal of Korean Medicine
• /
• v.38 no.2
• /
• pp.41-52
• /
• 2017

Objectives: Hataedock is indigenous treatment of Korean medicine that administers herbal extracts orally to newborn infants for remove the fetal heat. The purpose of this study was to evaluate skin lipid barrier formation effect of Hataedock treatment with Douchi. Methods: We measured the Western blot to observe the expression of protein such as involucrin and loricrin. Moreover, we observed immunohistochemical changes in NC/Nga mice. The 3-week-old NC/Nga mice were divided into 3 groups: the 3-week-old control group (3w-Ctrl), 5-week-old control group (5w-Ctrl), and the Hataedock-treated group (5w-FGT). Only the 5w-FGT group was treated with Douchi at the 3rd week. We identified the changes of the lipid skin barrier and protein differentiation through immunohistochemical changes of involucrin, loricrin, filaggrin and acid sphingomyelinase (ASM) in the stratum corneum. Results: The expression of involucrin and loricrin was increased in the Western blot that was treated with concentration of Douchi extracts. In 5w-FGT group, loricrin-positive reaction was increased by 54.0%, involucrin-positive reaction was increased by 84.0%, filaggrin-positive reaction was increased by 108.0% and ASM-positive reaction was increased by 91.0% in the stratum corneum. Conclusions: These results suggest that Hataedock treatment with Douchi promoted skin lipid barrier formation by promoting differentiation of keratinocytes.

• Proceedings of the Korea Society of Environmental Toocicology Conference
• /
• 2003.10a
• /
• pp.13-13
• /
• 2003

Methylmercury (MeHg) is a ubiquitous environmental toxicant that can be exposed to humans by ingestion of contaminated food including fish and bread. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of intracellular $Ca^{2+}$ levels (［$Ca^{2+}$］$_{i}$). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity. MeHg activated the acidic form of sphingomyelinase (A-SMase) and group IV cytosolic phospholipase $A_2$ ($cPLA_2$) downstream of PC-PLC, but these enzymes as well as protein kinase C were not linked to MeHg's toxicity. Furthermore, MeHg produced ROS, which did not cause the toxicity. However, D6O9, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner in MDCK and SH-5YSY cells. Addition of EGTA to culture media resulted in partial decrease of [$Ca^{2+}$］$_{i}$ and partially blocked cell death. In contrast, D609 completely prevented cell death with parallel decreases in diacylglycerol and ［$Ca^{2+}$］$_{i}$. Together, our findings indicated that MeHg-induced toxicity was caused by elevation of ［$Ca^{2+}$]$_{i}$ through activation of PC-PLC. The toxicity was not attributable to the signaling pathways such as $cPLA_2$, A-SMase, and PKC, or to the generation of ROS.

• Clinical and Experimental Reproductive Medicine
• /
• v.49 no.2
• /
• pp.93-100
• /
• 2022

Objective: The impact of imatinib, a tyrosine kinase inhibitor, on ovarian follicles and several proteins related to follicular function and apoptosis was investigated in mice. Methods: Saline, cyclophosphamide (Cp; 50 or 75 mg/kg), or imatinib (7.5 or 15 mg/kg) was injected once intraperitoneally into female B6D2F1 mice (18 mice in each group). In multiple ovarian sections, the number of various types of follicles and the proportion of good-quality (G1) follicles were counted. The levels of six proteins (anti-Müllerian hormone [AMH], BCL-xL, BAX, acid sphingomyelinase [A-SMase], caspase-3, and α-smooth muscle actin [α-SMA]) within the whole ovaries were quantified using Western blots. Results: Compared to the saline group, a significant reduction of the primordial follicle count was observed in the group treated with imatinib 7.5 and 15 mg/kg, as well as in the group treated with Cp 75 mg/kg. Administration of Cp significantly decreased the proportion of G1 primordial follicles, but administration of imatinib did not. No differences in the AMH, anti-apoptotic BCLX-L, pro-apoptotic BAX, and A-SMase levels in the ovarian tissues were observed among the five groups. However, caspase-3 and α-SMA levels were significantly higher in the imatinib and Cp groups than in the saline group. Conclusion: The administration of imatinib to mice significantly reduced the primordial follicle count and increased the protein levels of caspase-3 and α-SMA. Our findings suggest that imatinib potentially exerts ovarian toxicity via apoptotic processes, similarly to Cp.

• Journal of Life Science
• /
• v.22 no.6
• /
• pp.760-771
• /
• 2012

Marine triterpene glycosides are physiologically active natural compounds isolated from sea cucumbers(holothurians). It was demonstrated that they have a wide range of biological activities, including antifungal, cytotoxic, and antitumor effects. A previous study showed that stichoposide C (STC) isolated from Thelenota anax induces apoptosis through generation of ceramide by activation of acid sphingomyelinase (SMase) and neutral SMase in human leukemia cells. In this study, we investigated whether STD, a structural analog of STC, can induce apoptosis and examined the molecular mechanisms for its activity. It was found that STC and STD induce apoptosis in a dose- and time-dependent manner and lead to the activation of caspase-8, mitochondrial damage, activation of caspase-9, and activation of caspase-3 in K562 and HL-60 cells. STC activates acid SMase and neutral SMase, which results in the generation of ceramide. Specific inhibition of acid SMase or neutral SMase partially blocked STC-induced apoptosis, but not STD-induced apoptosis. In contrast, STD generates ceramide through the activation of ceramide synthase. Specific inhibition of ceramide synthase partially blocked STD-induced apoptosis, but not STC-induced apoptosis. Moreover, STC and STD markedly reduced tumor growth of HL-60 xenograft tumors and increased ceramide generation in vivo. These results indicate that STC and STD can induce apoptosis and have antitumor activity through the different molecular mechanisms, because they have a different sugar residue attached to aglycones. Thus, these results suggest that their actions are affected by a sugar residue attached to aglycones and they can be used as anticancer agents in the treatment of leukemia.