• Archives of Pharmacal Research
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• v.18 no.3
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• pp.189-194
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• 1995

The focus of this study was to investigate the influences of enzymatic scavengers of active oxygen metabolites and phospholipase $A_2$ inhibitor on hepatic secretory and microsomal function during hepatic ischemia/reperfusion. Rats were pretreated with free radical scavengers such as superoxide dismutase (SOD), catalase, deferoxamine and phospholipase $A_2$ inhibitor such as quinacrine and then subjected to 60 min. no-flow hepatic ischemia in vivo. After 1, 5 hr of reperfusion, bile was collected, blood was obtained from the abdominal aorta, and liver microsomes were isolated. Serum aminotransferase (ALT) level was increased at 1 hr and peaked at 5 hr. The increase in ALT was significantly attenuated by SOD plus catalase, deferoxamine and quinacrine especially at 5 hr of reperfusion. The wet weight-to-dry weight ratio of the liver was significantly increased by ischemia/reperfusion. SOD and catalase treatment minimized the increase in this ratio. Hepatic lipid peroxidiltion was elevated by ischemia/reperfusion, and this elevation was inhibited by free radical scavengers and quina crine. Bile flow and cholate output, but not bilirubin output, were markedly decreased by ischemia/reperfusion and quinacrine restored the secretion. Cytochrome $P_{450}$ content was decreased by ischemia/reperfusion and restored by free radical scavengers and quinacrine to the level of that of the sham operated group. Aminopyrine N-demethylase activity was decreased and aniline p-hydroxylase was increased by ischemia/reperfusion. The changes in the activities of the two enzymes were prevented by free radical scavengers and quinacrine. Our findings suggest that ischemia/reperfusion diminishes hepatic secretory functions as well as microsomal drug metabolizing systems by increasing lipid peroxidation, and in addition to free radicals, other factors such as phospholipase $A_2$ are involved in pathogenes of hepatic dysfunction after ischemia/reperfusion.

• Journal of Life Science
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• v.24 no.12
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• pp.1378-1382
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• 2014

Phospholipase D (PLD) catalyzes the hydrolysis of phospholipid to phosphatidic acid (PA), a lipid secondary messenger. Two forms of PLD isozymes, phosphatidylcholine-specific PLD1 and PLD2, have been identified. PLD has emerged as a critical regulator of cell proliferation and survival signaling, and dysregulation of PLD occurs in a various illnesses, including cancer. PLD activity is essential for cell survival and protection from apoptosis. Overexpression of PLD isozymes or PLD-generated PA attenuates the expression of apoptotic genes and confers resistance to apoptosis. The apoptosis-related molecular mechanisms of PLD remain largely unknown. Recently, the dynamics of PLD turnover during apoptosis have been reported. The cleavage of PLD isozymes as specific substrates of caspase differentially regulates apoptosis. PLD1 is cleaved at one internal site, and PLD2 is cleaved two sites at the front of the N-terminus. The cleavage of PLD1 reduces its enzymatic activity, probably via the dissociation of two catalytic motifs, whereas the cleavage of PLD2 does not affect the catalytic motifs and its activity. Thus, PLD2 maintains antiapoptotic capacity, despite its cleavage. Therefore, the differential cleavage pattern of PLD isozymes by caspase affects its enzymatic activity and antiapoptotic function. Thus, PLD is considered a potential target for cancer therapy. We summarize recent studies regarding the functional role of PLD in apoptosis.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.407-413
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• 1996

A novel type of extracellular phospholipase $A_1$ was isolated from Serratia sp. MK1 and purified to homogeneity by ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The purified enzyme was a monomer with a molecular mass of about 43, 000 Da. This enzyme showed the highest lipolytic activity toward phosphatidylserine among the phosphoglycerides tested, and preferentially catalyzed the hydrolysis of the ester bond in phosphatidic acid to lyso-phosphatidic acid. Enzyme activity was completely inhibited by the addition of a chelating agent such as EDTA, and inhibited enzyme activity was fully recovered by the presence of $Ca^{2+}$. This implies that the enzyme requires $Ca^{2+}$ for activity. The enzyme was stable up to $70^{\circ}C$ when incubated for 1 h at pH 8.5, and the optimal pH and temperature were 8.5 and $50^{\circ}C$, respectively.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.721-723
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• 2000

The phospholipase $A_2$-catalyzed transesterification of phosphatidylcholine (PC, 95%) with nervonic acid (NA, 95%) was successfully carried out in an organic solvent. The maximum yield after 48 h was 10.3% (w/w) at $50^{\circ}C$ with an initial water activity ($a_w$) of 0.16, and a molar ratio of NA to PC of 20 in 5 ml ethyl acetate.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2000.04a
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• pp.15-16
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• 2000

Transient forebrain ischemia results in delayed neuronal death in the CA1 region of the hippocampus after injury, which is, at least in part, a consequence of excessive generation of reactive oxygen species. Previous in vitro studies using cell cultures or brain slices have demonstrated that phospholipase D (PLD) in the nervous system is involved in the signaling mechanism in response to a variety of agonists. Several recent studies have shown that reactive oxygen species stimulate phospholipase D (PLD) activity in several kinds of cells. Therefore, this raises the possibility that PLD activity is enhanced in the ischemic brain. Meanwhile, osteopontin (OPN) was initially identified as a sialoglycoprotein in bone, but has since been found in various tissues. Although not much is known about its function, OPN seems to play an important role in inflammation and tissue repair. Recently, it was reported that OPN was upregulated in the activated microglia after focal brain ischemia, suggesting that OPN might play a role in wound healing after a focal stroke.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.8
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• pp.1091-1097
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• 2002

Capacitated goat spermatozoa generated diacyl glycerol (DAG) when suspended in Krebs-Ringer bicarbonate medium and induced by progesterone or $Ca^{2+}$ ionophore A23187. We have added Sn-1-oleoyl-2-acetyl glycerol externally, to study the effect of DAG in goat sperm acrosomal exocytosis. Addition of neomycin abolished the DAG generating capacity of progesterone in a dose dependent manner, suggesting the involvement of a phosphoinositidase C activated phospholipase C system in the process. The level of increase in phosphatidic acid was considerably low and was produced well after the DAG generation thereby suggesting the involvement of a DAG kinase which phosphorylates DAG to produce PA. The inhibition of progesterone mediated effect by inhibitors of $GABA_A/Cl^{-}$ channel and $Ca^{2+}$ channels further supports the evidence that the events of binding of agonist to the receptor(s), opening of $Ca^{2+}$ channels and the activation of phospholipase C are reconciled to perform the function of acrosome reaction in capacitated goat spermatozoa.

• Toxicological Research
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• v.21 no.4
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• pp.291-295
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• 2005

To define the effect of silica on the stimulator of signaling pathway, we studied the phospholipase D (PLD) activity in the Rat2 fibroblasts. Silica stimulated the accumulation of labeled $[^3H]$ phosphatidylethanol$([^3H]\;PEt)$ in a time- and concentration-dependent manner. This Silicainduced PLD activity was partially attenuated by the pretreatment with U73122 (phospholipase C inhibitor), genistein (protein tyrosine kinase inhibitor), PD 98056 (MEK inhibitor) and mepacrine (phospholipase $A_2$ inhibitor). But, sphingosine (protein kinase C inhibitor) and DPI (NADPH reductase inhibitor) had not effect the PLD activity. Silica also increased the PLD activity about four fold, which imply that the PLD activity is more influenced by the mobilization of PLD than other signaling mediators. The PLD activity also partially inhibited calcium chelator EGTA or/and BAPTA/AM compared to silica. Finally, we concluded that a silica-stimulated phospholipase D activity is present in the Rat2 fibroblasts and is modulated by combination of various signaling mediators.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.58-58
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• 1995

식물에서부터 새로운 소염작용제를 개발하기 위하여 여러식물을 대상으로 염증반응의 초기단계에서 중요한 역할을 하는 것으로 알려진 Phospholipase $A_2$에 저해활성을 갖는 물질을 검색하였고 그 중 강한 억제활성을 보인 유근피에서 유효성분을 분리하였다. 유근피의 에칠 아세테이트 분획에 대하여 실리카겔 크로마토그래피, Sephadex LH-20 크로마토그래피, 분취 박막 크로마토그래피를 수행하여 phenol성 -OH기를 갖는 활성성분인 PSH-II-84-1를 분리하였다. $^1$H-NMR 신호의 양상과 짝지움 상수 값에서 분리된 물질은 (+)-catechin 의 당 유도체로 확인되었다. $^{13}$C-NMR 자료를 분석하여 치환된 당은 D-apiofuranose로 확인되었다. 방향족환의 $^{l3}$C-NMR 신호들은 extended Huekel theory를 응용하여 얻은 net charge 계산 값과 상관시켜 할당하였다. 이상의 구조연구 결과 이 물질은 (+)-catechin-7-0-$\beta$-D-apiofuranoside로 밝혀졌다. (+)-catechin-7-0-$\beta$-D-apiofuranoside의 효소억제활성은 Type II Phospholipase $A_2$에 대하여 $IC_{50}$/이 600$\mu$M이었다.다.

• YAKHAK HOEJI
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• v.46 no.3
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• pp.192-196
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• 2002

To investigate the effect of intravenous ethanol administration on pancreatic exocrine secretion, we measured volume and protein amount in pancreatic juice and assayed amylase activity and phospholipase $A_2$ activity in pancreatic fragments and serum. Acute pancreatitis induced by obstruction of common bile-pancreatic duct (CBPD) and caerulein infusion (5 $\mu\textrm{g}$/kg/hr) showed typical characteristics, such as hyperamylasemia and pancreatic edema and increase of phospholipase $A_2$ activity in pancreatic fragments and serum. Intravenous ethanol infusion (50 mg/kg/hr) significantly stimulated pancreatic exocrine secretion, but such a stimulatory effect of ethanol disappeared at dose of 100 mg/kg/hr without typical symptoms of acute pancreatitis. In microscopic examination, there were no typical changes of edematous pancreatitis in ethanol administrated rats. These results suggest that acute ethanol administration has dual effect on exocrine pancreatic secretion: low dose of ethanol (50 mg/kg/hr) stimulates pancreatic exocrine secretion, whereas high dose of ethanol (100 mg/kg/hr) does not without typical changes of edematous pancreatitis.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1266-1272
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• 2016

Phospholipase C is a key enzyme of signaling pathways hydrolyzed phosphatidylinositol 4,5-bisphosphate to generate 2 second messengers. Among the PLC, $PLC-{\beta}$ subfamily consisted of 4 isoforms, $PLC-{\beta}$ 1~4. Here, we studied the tissue specific expression of $PLC-{\beta}3$ in olive flounder (Paralichthys olivaceus) following external stimulation like lipopolysaccharide (LPS), concanavalin A (ConA) and environmental stress compared with the inflammatory cytokines IL-1b. $PoPLC-{\beta}3$ gene transcripts has the effect in stimulated tissue compared to control. These results provide what we sure to be a important role for $PLC-{\beta}3$ activity in tissue and verify $PLC-{\beta}3$ as potential immune enzyme for signal transduction.