Studies on mammalian Ca^<2+>-dependent phospholipase A_2s

哺乳动物Ca^2依赖性磷脂酶A_2s的研究

• 批准号: 09470507
• 负责人: KUDO Ichiro
• 金额: $ 8.38万
• 依托单位: Showa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09470507/
• 关键词: Phospholipase A_2; Cyclooxygenase; Prostagrandin; Arachidonic acid; Phospholipid; ホスホリパーゼA2; アラキドン酸代謝; cPLA_2; sPLA_2; COX; アポトーシス

Phospholipase A_2 (PLA_2) represents a growing family of enzymes that catalyze the hydrolysis of phospholipids at the sn-2 position, liberating free fatty acids inducing arachidonic acid (AA), a precursor of bioactive eicosanoids, and lysophospholipids. PLA_2 has been implicated in diverse cellular responses, such as signal transduction, host defense, blood coagulation, cigestion, and membrane remodeling. Accorcing to an updated classification, PLA2_2 can be subdivided into several groups based upon their stnictures and enzymatic characteristics, inducing Ca^2-dependent cytosolic (cPLA_2) and secretory (sPLA_2) PLA_2 isozymes and Ca^<2+>-independent PLA_2 (iPLA_2). In the present study, the functional coupling of several clstinct PLA_2s and two cyclooxygenase (COX) isoforms during immediate and delayed PG-biosynthetic responses was examined cPIA_2, sPLA_2-IIA and sPLA_2-V were " signaling PLA-_2s" that promoted AA release from cells after stimulation with ionophore or bradykinin, which … More evoked the immediate response, and IL-1, which induced the delayed response. AA released by these signaling PLA_2s was converted to PGE_2 by both COXs during the immediate response and pretbminantly by COX-2 during the dulayed response. iPLA,, which plays a crucial role in "phospholipid remodeling', failed to couple with COX-2 during the delayed response, whereas it was linked to ionophore-induced immeciate PGE_2 generation via COX-l in preference to COX-2. sPLA_2-X induced fatty acid release in a manner similar to iPIA_2 rather than other sPLA2s. Extracellular sPLA_2s-IIA and -V.but neither intracellular cPLA_2 nor iPLA_2, augmented PGE_2 synthesis by neighboring COX-expressing cells, implying that these sPLA_2s play a particular role as paracrine amplifiers of the PG-biosynthetic response signal from one cell to another. After cell activation, signaling PLA_2s were localized around the nucleus where both COX isozymes were present. cPLA_2 bound to vimentin, a perinuclear intermeiziate filament protein, in Ca^<2+>-dependent manner and translocated from the cytosol to perinuclear membrane. sPLA_2-IIA bound a GPI-anchored heparan sulfate proteoglycan glypican, which &livered sPLA_2-IIA into caveolae and perinuclear sites and augmented sPLA_2-IIA-meciated A.A release and PGE_2 generation. Less

磷脂酶A_2（PLA_2）是近年来发展起来的一个酶家族，它催化磷脂的sn-2位水解，释放游离脂肪酸，诱导产生花生四烯酸（AA）和溶血磷脂。PLA_2参与多种细胞反应，如信号转导、宿主防御、凝血、消化和膜重塑等。根据最新的分类方法，PLA2_2可根据其结构和酶学特性分为几类，包括Ca^2依赖性胞浆型（cPLA_2）和分泌型（sPLA_2）PLA_2同工酶以及Ca^2+非依赖性PLA_2（iPLA_2）。本研究探讨了几种典型的PLA-2和两种环氧合酶（考克斯）同工酶在PG生物合成的即刻和延迟反应中的功能偶联。cPIA_2、sPLA_2-IIA和sPLA_2-V是“信号PLA-2”，在离子载体或缓激肽刺激后促进AA从细胞释放， ...更多信息 诱发立即反应，和IL-1，诱导延迟反应。这些信号PLA_2释放的AA在即刻反应中被COX转化为PGE_2，在延迟反应中被考克斯-2转化为PGE_2。在“磷脂重塑”中起关键作用的iPLA在延迟反应期间未能与考克斯-2偶联，而其与离子载体诱导的PGE_2生成有关，其通过COX-1而不是考克斯-2。sPLA_2-X以类似于iPIA_2的方式诱导脂肪酸释放，而不是其他sPLA_2。细胞外sPLA_2s-IIA和-V，而细胞内cPLA_2和iPLA_2均不能促进邻近COX表达细胞的PGE_2合成，这意味着这些sPLA_2s作为PG生物合成反应信号的旁分泌放大器从一个细胞到另一个细胞起着特殊的作用。细胞活化后，信号PLA_2定位于细胞核周围，其中存在两种考克斯同工酶。cPLA_2以Ca^2+依赖的方式与核周中间丝蛋白vimentin结合，并从胞浆转位到核周膜。sPLA_2-IIA与GPI锚定的硫酸乙酰肝素蛋白聚糖磷脂酰肌醇蛋白聚糖结合，使sPLA_2-IIA进入胞膜小窝和核周部位，促进sPLA_2-IIA介导的A. A释放和PGE_2生成。少

项目成果

Atsumi, G., Tajima, M., Hadano, A., Nakatani, Y., Murakami, M., and Kudo, I.: "Fas-induced arachidonic acid release is mediated by Ca^<2+>-independent phospholipase A_2 but not cytosolic phospholipase A_2 which undergoes proteolytic inactivation." Biol.Ch

Atsumi, G.、Tajima, M.、Hadano, A.、Nakatani, Y.、Murakami, M. 和 Kudo, I.：“Fas 诱导的花生四烯酸释放是由 Ca^2 独立的磷脂酶 A_2 介导的

Naraba, H., Murakami, M., Matsumoto, H., Shimbara, S., Ueno, A., Kudo, I., and Oh-ishi, S.: "Segregated coupling of phospholipases A_2, cyclooxygenases, and terminal prostanoid synthases in different phases of prostanoid biosynthesis in rat peritoneal mac

Naraba, H.、Murakami, M.、Matsumoto, H.、Shimbara, S.、Ueno, A.、Kudo, I. 和 Oh-ishi, S.：“磷脂酶 A_2、环氧合酶和末端前列腺素的分离偶联

Atsumi, G.et al.: "Fas-induced arachidonic acid release is mediated by Ca^<2+>-independent phospholipase A_2 but not cytosolic phospholipase A_2, which undergoes proteolytic inactivation." J.Biol.Chem.273. 13870-13877 (1998)

Atsumi, G.等人：“Fas 诱导的花生四烯酸释放是由 Ca^2 独立的磷脂酶 A_2 介导的，但不是胞质磷脂酶 A_2，后者会经历蛋白水解失活。”

Murakami, M., Kambe, T., Shimbara, S., and Kudo, I.: "Functional coupling between various phospholipase A_2s and cyclooxygenases in immdeiate and delayed prostanoid biosynthetic pathways." J.Biol.Chem.274. 3103-3115 (1999)

Murakami, M.、Kambe, T.、Shimbara, S. 和 Kudo, I.：“立即和延迟前列腺素生物合成途径中各种磷脂酶 A_2 和环氧合酶之间的功能耦合。”

Tada, K., Murakami, M., Kambe, T., and Kudo, I.: "Induction of cyclooxygenase-2 by secretory phospholipase A_2s in nerve growth factor-stimulted rat serosal mast cells is facilitated by interaction with fibroblasts and mediated by a mechamism independent

Tada, K.、Murakami, M.、Kambe, T. 和 Kudo, I.：“在神经生长因子刺激的大鼠浆膜肥大细胞中，分泌性磷脂酶 A_2 对环氧合酶 2 的诱导是通过与成纤维细胞的相互作用来促进的，并由