Fluid-phase pinocytosis of native low density lipoprotein promotes murine M-CSF differentiated macrophage foam cell formation.
Fluid-phase pinocytosis of native low density lipoprotein promotes murine M-CSF differentiated macrophage foam cell formation.
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DOI：
10.1371/journal.pone.0058054
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Kruth HS
中科院分区：
文献类型：
--
作者：
Barthwal MK;Anzinger JJ;Xu Q;Bohnacker T;Wymann MP;Kruth HS
在动脉粥样硬化期间，低密度脂蛋白(LDL)衍生的胆固醇在巨噬细胞中积聚，形成泡沫细胞。巨噬细胞摄取低密度脂蛋白可促进泡沫细胞的形成，但其机制尚不清楚。本研究探讨巨噬细胞集落刺激因子(M-CSF)分化的小鼠骨髓来源的巨噬细胞摄取低密度脂蛋白的机制。低密度脂蛋白受体缺失(低密度脂蛋白受体−/−)巨噬细胞与低密度脂蛋白孵育后，显示出胆固醇的非饱和积聚，在所研究的24小时内没有下调。随着~(125)I-−/−浓度的增加，低密度脂蛋白受体巨噬细胞呈现非饱和摄取低密度脂蛋白。过量20倍的未标记低密度脂蛋白对野生型巨噬细胞摄取~(125)I-低密度脂蛋白没有影响，巨噬细胞清道夫受体CD36和SRA的基因缺失也不影响~(125)I-低密度脂蛋白的摄取，表明摄取低密度脂蛋白是通过液体相吞噬作用发生的，而不是通过受体。用LY294002或Wortmannin治疗的野生型和低密度脂蛋白−/−小鼠的胆固醇积累被抑制约50%，这是所有类型的磷脂酰肌醇3-激酶(PI3K)的抑制剂。时间推移，相差显微镜显示，巨噬细胞吞噬，一个重要的液相摄取途径，几乎完全被抑制PI3K与Wortmannin。药物抑制I类PI3K亚型α、β、γ或Delta不会影响巨噬细胞低密度脂蛋白衍生的胆固醇积聚或巨噬细胞吞噬。此外，与野生型巨噬细胞相比，表达KI死亡类PI3Kβ、γ或Delta亚型的小鼠巨噬细胞在胆固醇积聚或巨噬细胞吞噬方面没有减少。因此，非I类PI3K亚型介导了巨噬细胞的巨噬细胞吞噬作用。对低密度脂蛋白摄取、胆固醇积聚和巨噬细胞增多所需成分的进一步鉴定表明，动力素、微管、肌动蛋白和空泡型H(+)-ATPase有助于摄取。然而，在某些其他类型的细胞中，介导液相吞饮的pak1、rac1和src家族的激酶是不必要的。综上所述，我们的发现提供了证据，证明用抑制剂靶向那些介导巨噬细胞巨噬细胞吞噬作用的成分可能是限制巨噬细胞在动脉中积聚低密度脂蛋白来源胆固醇的有效策略。
During atherosclerosis, low-density lipoprotein (LDL)-derived cholesterol accumulates in macrophages to form foam cells. Macrophage uptake of LDL promotes foam cell formation but the mechanism mediating this process is not clear. The present study investigates the mechanism of LDL uptake for macrophage colony-stimulating factor (M-CSF)-differentiated murine bone marrow-derived macrophages. LDL receptor-null (LDLR−/−) macrophages incubated with LDL showed non-saturable accumulation of cholesterol that did not down-regulate for the 24 h examined. Incubation of LDLR−/− macrophages with increasing concentrations of 125I-LDL showed non-saturable macrophage LDL uptake. A 20-fold excess of unlabeled LDL had no effect on 125I-LDL uptake by wild-type macrophages and genetic deletion of the macrophage scavenger receptors CD36 and SRA did not affect 125I-LDL uptake, showing that LDL uptake occurred by fluid-phase pinocytosis independently of receptors. Cholesterol accumulation was inhibited approximately 50% in wild-type and LDLR−/− mice treated with LY294002 or wortmannin, inhibitors of all classes of phosphoinositide 3-kinases (PI3K). Time-lapse, phase-contrast microscopy showed that macropinocytosis, an important fluid-phase uptake pathway in macrophages, was blocked almost completely by PI3K inhibition with wortmannin. Pharmacological inhibition of the class I PI3K isoforms alpha, beta, gamma or delta did not affect macrophage LDL-derived cholesterol accumulation or macropinocytosis. Furthermore, macrophages from mice expressing kinase-dead class I PI3K beta, gamma or delta isoforms showed no decrease in cholesterol accumulation or macropinocytosis when compared with wild-type macrophages. Thus, non-class I PI3K isoforms mediated macropinocytosis in these macrophages. Further characterization of the components necessary for LDL uptake, cholesterol accumulation, and macropinocytosis identified dynamin, microtubules, actin, and vacuolar type H(+)-ATPase as contributing to uptake. However, Pak1, Rac1, and Src-family kinases, which mediate fluid-phase pinocytosis in certain other cell types, were unnecessary. In conclusion, our findings provide evidence that targeting those components mediating macrophage macropinocytosis with inhibitors may be an effective strategy to limit macrophage accumulation of LDL-derived cholesterol in arteries.
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影响因子：
6.5
作者：
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通讯作者：
Kruth, Howard S.
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非本地低密度脂蛋白颗粒诱导泡沫细胞形成的受体非依赖性流体性胞毒性机制。
影响因子：
4.4
作者：
Kruth HS
通讯作者：
Kruth HS
影响因子：
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作者：
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