• YAKHAK HOEJI
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• v.46 no.1
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• pp.58-62
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• 2002

The underlying mechanism by which the reflux of gastric juice elicits oesophagitis remaind unclear. To investigate inflammatory response to HCI in tissue of esophagus and lower esophageal sphincter experimental esophagitis was elicited by perfusion of 0.1 N HCI in cats. There was no difference in phospholipase $A_2$ (PLA$_2$) activity of tissue between control and esophagitis. Myeloperoxidase activity in esophagitis was significantly greater than that of control. However histamine content in esophageal mucosa of esophagitis was significantly smaller than that of control. These finding suggest that inflammatory response to HCI in esophagitis is related to changes of myeloperoxidase activity and histamine rather than change of PLA$_2$ activity.

• Proceedings of the Korean Biophysical Society Conference
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• 1998.06a
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• pp.30-30
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• 1998

The effects of capsaicin on phospholipase (PLC)-induced capacitative $Ca^{2＋}$ entry (CCE) were investigated in PC12 cells. Capsaicin inhibited one of PLC-linked signal, extracellular ATP-induced norepinephrine secretion with a concentration range, 10-100 $\mu$M. Capsaicin did not inhibit the peak portion of extracellular ATP-mediated [Ca$^{2＋}$]i rise, but it recovered more rapidly to the normal level of [Ca$^{2+}$]i from the sustained [Ca$^{2+}$]i level.(omitted)ted)

• BMB Reports
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• v.45 no.1
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• pp.7-13
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• 2012

Phospholipase D (PLD), a superfamily of signaling enzymes that most commonly generate the lipid second messenger Phosphatidic Acid (PA), is found in diverse organisms from bacteria to man and functions in multiple cellular pathways. A fascinating member of the family, MitoPLD, is anchored to the mitochondrial surface and has two reported roles. In the first role, MitoPLD-generated PA regulates mitochondrial shape through facilitating mitochondrial fusion. In the second role, MitoPLD performs a critical function in a pathway that creates a specialized form of RNAi required by developing spermatocytes to suppress transposon mobilization during meiosis. This spermatocyte-specific RNAi, known as piRNA, is generated in the nuage, an electron-dense accumulation of RNA templates and processing proteins that localize adjacent to mitochondria in a structure also called intermitochondrial cement. In this review, we summarize recent findings on these roles for MitoPLD functions, highlighting directions that need to be pursued to define the underlying mechanisms.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.21-22
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• 2001

Phospholipase A$_2$(PLA$_2$) comprise a family of enzymes that hydrolyze the acyl bond at the sn-2 position of phospholipids to generate free fatty acids including arachidonic acid and lysophospholipids. Distinct forms of PLA$_2$are involved in digestion, inflammation, and intercelluar-and intracellular signaling pathways. The released arachidonic acid, which is enriched at the sn-2 position, serves as the precursor for eicosanoids such as prostaglandins and leukotrienes. During oxygenation of arachidonic acid to hydroxy endoperoxide, reactive oxygen radicals are generated. On the other hand, lysophospholipids increase membrane fluidity and can be cytotoxic with its detergent-like action. Thus, the biochemical features of the products of PLA$_2$activity suggest that PLA$_2$may be implicated in many destructive cellular processes.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.168-171
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• 2000

The thermal stability and catalytic activity of phospholipase A$_1$ from Serratia sp. MK1 were improved by an evolutionary molecular engineering. Two thermostable mutants were isolated after sequential rounds of error-prone PCR to introduce random mutations and filter-based screening of the resultant mutant library, and identified as having six (mutant TA3) and seven (mutant TA13) amino acid substitutions, respectively. Different types of the substitutions were found in two mutants, resulting in the increase of nonploar residues (mutant TA3) or changes between side chains within polar or charged residues (mutant TA13). The wild-type and mutant enzymes were purified, and the effect of temperature on their stability and catalytic activity was investigated. The T$\sub$m/ values of TA3 and TA13 were increased by 7 and 11$^{\circ}C$, respectively. Thus, evolutionary molecular engineering was found to be an effective and efficient approach to increasing thermostability without compromising enzyme activity.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.407-412
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• 2001

A $Ca^{2+}$_dependent PLA$_2$activity termed rPLA$_2$, was detected in the cytosol of bovine red blood cells (RBCs). The rPLA$_2$was characterized as a similar form to Group IV cPLA$_2$, but different in several column chromatographic profiles including an anion exchange column. To examine whether this rPLA$_2$is different from the well characterized cPLA$_2$, a quinone derivative, BJ50, was developed and tested for the inhibitory effect on the two PLA$_2$enzymes. The rPLA$_2$activity was inhibited by a quinone derivative (BJ50) with ID$_{50}$ of 20 $\mu$M., but had no effect on the cPLA$_2$, suggesting that rPLA$_2$may be a novel type of cytosolic PLA$_2$in RBCs.s.s.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.117-123
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• 1999

Because of the potent effects of lipid mediators such as prostaglandins (PGs), leukotriens (LTs) and platelet activating factor (PAF) on a variety of cells and tissues, they are considered as major contributors to the process leading to inflammation and allergy. To pursue the mechanism of anti-inflammatory activity of Lonicera japonica, we tested inhibitory effects of 7 flavonoids from Lonicera japonica on arachidonic acid cascade related enzymes, such as inflammatory phospholipase $A_2$, cyclooxygenase-1 and 2, 5-lipoxygenase, in bone marrow derived mast cell (BMMC), and lyso PAF-acetyltransferase in rat spleen microsomes. Anti-inflammatory activities of lonicera japonica are thought to be attributed at least in part to the inhibition of arachidonic acid cascade releated enzymes by flavonoids such as apigenin, luteolin quercetin.

• Journal of Ginseng Research
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• v.21 no.1
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• pp.19-27
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• 1997

The present study was conducted to assess the effect of total saponins from Korean red ginseng on the biosynthesis of inositol phospholipids in vivo and also effects on the metabolic enzymes, such as phosphatidylinositol-specific phospholipase C(Pl-PLC) and PI-kinases. The administration of 0.1% saponin solution, 0.1 ml 3 times a day intraperitoneally to 5 mice for 30 days has increased a 23% of the body weight when it compared with a control group. The amounts of 32P-phoschorus radioactivity incorporated into the phosphoinositides from the liver and brain tissues have increased a 310% and 260%, respectively, in the saponin treated mice. The activities of PI-PLC from liver and brain were stimulated in the various amounts by the conditions treated with saponins. The PI-kinases from liver and brain were also activated by saponins, but its effect was lower than that of PI-PLC. From these results, it was confirmed that red ginseng saponins have affected positively not only on the biosynthesis of phosphoinositides but also on the PI-PLC and PI-kinases related to the cellular signal transduction.

• YAKHAK HOEJI
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• v.47 no.2
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• pp.69-77
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• 2003

Arachidonic acid (AA), which is stored in membrane glycerophospholipids, is liberated by phospholipase $A_2$ (PLA$_2$) enzymes and is sequentially converted to cyclooxygenases (COXs) and lipoxygenases (LOXs) then to various bioactive PGs, and LTs. In order to find the specific inhibitors of AA metabolism especially PLA$_2$, COX-2, 5-LO and lyso PAF acetyltransferase, 120 Korean residential plants extracts were evaluated for their inhibitory activity on PGD$_2$, LTC$_4$ production from cytokine-induced mouse bone marrow-derived mast cells (BMMC) and arachidonic acid released from phospholipid and PAF production from lyso PAF. From this screening procedure, methanol extract of ten indigenous plant such as Salix gracilistyla, Sedum kamtschaticum, Cirsium chanroenicum, Hypericum ascyron, Astilbe chinensis, Agrimonia pilosa, Aristolochia manshuriensis, Vodia daniellii, Pyrola japonica, Styrax obassia were found to inhibit production of inflammatory mediators in vitro assay system.

• Tuberculosis and Respiratory Diseases
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• v.68 no.2
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• pp.55-61
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• 2010

Background: The underlying pathogenesis of fat embolism-induced acute lung injury (ALI) has not been elucidated. In the present study, the pathogenesis of fat embolism-induced ALI was probed in association with neutrophilic oxidative stress in oleic acid (OA)-induced ALI of S-D rats. Methods: OA was injected intravenously to provoke ALI in experimental rats. Five hours later, indices of ALI were measured to confirm the role of the neutrophilic respiratory burst. The effect of an inhibition of phospholipase A2 (PLA2) was also evaluated. Results: The accumulation of neutrophils in the lung due to OA caused increased neutrophilic oxidative stress in lung, which was ameliorated by mepacrine. What were the results from inhibition of PLA2. Conclusion: Excess neutrophilic oxidative stress contributes to OA-induced ALI, which is lessened by the inhibition of PLA2.