HDL-apoAI gene expression and its kinetics in vivo

HDL-apoAI基因表达及其体内动力学

• 批准号: 04671503
• 负责人: SAKU Keijiro
• 金额: $ 0.9万
• 依托单位: Fukuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04671503/
• 关键词: high-density lipoprotein; apoprotein AI; turnover study; proapolipoprotein AI; rabbit; messenger RNA; varinat apoprotein AI

The metabolic turnover of HDL-apo AI has been studied in order to know the mechanism of low and high plasma HDL levels.1) We attempted here to determine the kinetic parameters (turnover) of HDL apo AI in normal Japanese White (control) rabbits, with or without cholesterol, probucol and pravastatin feeding. ^<125>l-labeled HDL was injected intraveneously and blood samples were taken periodically for 6 days. Kinetic parameters were calculated from the apo AI specific radioactivity decay curves. We found that the apo AI fractional catabolic rates (FCR) in rabbits fed pravastatin with Ch (group 1) were significantly less than those in rabbits fed pravastatin plus probucol with Ch (group 2) (0.546(〕SY.+-.〔)0.017 /day vs. 0.730(〕SY.+-.〔)0.126 /day, p<0.05), while the synthetic rates (SR) of apo AI was lower in group 2 than in group 1 (14.76(〕SY.+-.〔)1.71 mg/kg/day vs. 11.21(〕SY.+-.〔)2.38 mg/kg/day.respectively, p<0.1) . These data indicate that pravastatin and probucol have different effects … More on HDL-apo AI kinetics in a diet which includes cholesterol. The addition of pravastatin to probucol did not enhance HDL metabolism in this expermental models, but rather reduce the synthesis of Apo AI.Total RNA was isolated from rabbit intestine under various conditions as stated above. Compared to findings in control rabbits, probucol or pravastatin treated rabbits showed no changes in mRNA level of apo AI.2) In vivo conversion of recombinant human proapoprotein AI (rh-Met-proapo AI) from E.coli to apo AI was also investigated in rabbits in vivo. It was found that the radioactivity of rh-Met-proapo AI migrated to more acidic isoproteins, the conversion was complete within 24 hours. Thus, a) the proteolytic cleavage of proapo AI is an extracellular event, b) the converting enzyme from rabbits is functional for human proapo AI processing, and c) the injection of rh-Met-proapo AI into rabbits facilities understanding of the early events of HDL biogenesis in rabbits.3) In vivo kinetics of lipoprotein(a) [Lp(a)] were also investigated in homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model of familial hypercholesterolemia, and in normolipidemic Japanese White rabbits (controls). The fractional catabolic rates (FCRs) of both Lp(a) and LDL (1.355(〕SY.+-.〔)0.189 pools per day and 1.278(〕SY.+-.〔)0.397 pools per day, respectively) in the WHHL rabbits were significantly (p<0.005) smaller than those in the control rabbits (2-008(〕SY.+-.〔)0.083 pools per day and 2.855(〕SY.+-.〔)0.759 pools per day, respectively) . Our data storongly suggest that Lp(a) clearance is not entirely dependent upon LDL receptors and may be mediated by some other mechanisms.4) We found six types of apo AI variants. They were radiolabeled and injected into rabbits as above. We found no peculiar pathway for apo AI variants compated to the kinetics of native apo Al(Al_3) . Less

为了解高、低血浆高密度脂蛋白水平的机制，对高密度脂蛋白-载脂蛋白AI代谢代谢进行了研究。1)测定正常日本大白兔喂饲或不喂饲胆固醇、普罗布考和普伐他汀后，高密度脂蛋白-载脂蛋白AI代谢动力学参数。静脉注射L标记的高密度脂蛋白，定期采血6d。根据载脂蛋白AI比放射性衰变曲线计算动力学参数。结果表明，普伐他汀加CH组(第1组)的载脂蛋白AI分解率(Fcr)显著低于普伐他汀加普罗布考加CH组(第2组)(0.546±±0.017次/天vs.0.730±0.126次/天，p&lt；组2的载脂蛋白AI合成率(SR)低于组1(分别为14.76±1.71 mg/kg/d和11.21±2.38 mg/kg/day，P<0.01)。这些数据表明普伐他汀和普罗布考对…有不同的影响更多关于高密度脂蛋白-载脂蛋白AI在包括胆固醇的饮食中的动力学。普罗布考中加入普伐他汀并不能促进高密度脂蛋白的代谢，反而降低载脂蛋白AI的合成。在上述各种条件下，从兔肠道中提取总RNA。与对照组相比，普罗布考和普伐他汀对载脂蛋白AI的mRNA水平没有影响。2)体内实验还观察了重组人载脂蛋白AI(rh-Met-proapo AI)从大肠杆菌到载脂蛋白AI的体内转化。发现rh-Met-proapo AI的放射性迁移到更酸性的同工蛋白上，在24小时内完成转化。因此，a)Proapo AI的蛋白水解性切割是一个细胞外事件，b)来自兔的转换酶对人类Proapo AI的加工具有功能，以及c)将rh-Met-proapo AI注射到兔体内有助于了解兔高密度脂蛋白生物发生的早期事件。3)还研究了家族性高胆固醇血症纯合子Watanabe遗传性高脂血症(WHHL)兔和正常血脂血症日本大白兔(对照组)脂蛋白(A)[Lp(A)]的体内动力学。白兔Lp(A)和低密度脂蛋白(Lp(A))和低密度脂蛋白(Ldl)(分别为1.355、0.189和1.278、0.397、0.397)的分解率(FCR)均显著小于对照组(分别为200、0.083、2.855、0.759和0.759)(p&lt；0.005)。我们的数据表明，Lp(A)的清除并不完全依赖于低密度脂蛋白受体，可能是由一些其他机制介导的。4)我们发现了六种类型的载脂蛋白AI变体。如上所述，将它们标记并注射到兔体内。我们没有发现载脂蛋白AI变异体与天然载脂蛋白Al(Al_3)的动力学相比的特殊途径。较少

项目成果

Saku,K.et al: "Combined therapy with probucol and pravastatin in hypercholesterolemia." European Journal of Clinical Pharmacology. 44. 535-539 (1993)

Saku,K.等人：“普罗布考和普伐他汀联合治疗高胆固醇血症。”

Bai,H.,Saku,K.et al: "Polymorphic site study at codon 347 of apolipoprotein A-IV in a Japanese population" Biochimica et Biophysica Acta. 1174. 279-281 (1993)

Bai,H.,Saku,K.等人：“日本人群中载脂蛋白 A-IV 密码子 347 的多态性位点研究”Biochimica et Biophysicala Acta。

Saku, K.et al: "In vivo conversion of recombinant human proapolipoprotein AI to apolipoprotein AI." Biochimica et Biophysica Acta.1217. 29-30 (1994)

Saku, K.等人：“重组人载脂蛋白原 AI 体内转化为载脂蛋白 AI。”

Bai,H.,Saku,K.et al: "Polymorphic site study at dodon 347 of apolipoprotein A-IV in a Japanese population." Biochimica et Biophysica Acta. 1174. 279-281 (1993)

Bai,H.,Saku,K.等人：“日本人群中载脂蛋白 A-IV dodon 347 的多态性位点研究。”

Okura,Y.,Saku,K.et al: "Serum lipoprotein(a) in maintenance hemodialysis patients" Nephron. (1993)

Okura,Y.,Saku,K.等人：“维持性血液透析患者的血清脂蛋白（a）”肾单位。