Insights into the fate of the N-terminal amyloidogenic polypeptide of ApoA-I in cultured target cells
Insights into the fate of the N-terminal amyloidogenic polypeptide of ApoA-I in cultured target cells
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DOI：
10.1111/j.1582-4934.2011.01271.x
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发表时间：
2011-12-01
影响因子：
5.3
通讯作者：
Piccoli, Renata
中科院分区：
文献类型：
--
作者：
Arciello, Angela;De Marco, Nadia;Piccoli, Renata
载脂蛋白A-I（ApoA-I）是一种细胞外脂质受体，其在胆固醇流出和高密度脂蛋白形成中的作用由ATP结合盒转运体A1（ABCA 1）介导。然而，一些ApoA-I变体与全身性淀粉样变性相关，其特征在于外周器官中的细胞外原纤维沉积。发现心脏淀粉样纤维主要由ApoA-I的93个残基的N-末端片段构成，命名为[1-93]ApoA-I。在本文中，大鼠成心肌细胞被用作靶细胞来分析与全长ApoA-I相比的纤维形成多肽的结合、内化和细胞内命运。我们提供的证据表明，多肽：（i）结合到细胞膜上的特定位点（Kd= 5.90 +/- 0.70 x 10-7 M），其中它与ABCA 1部分共定位，也如对ApoA-I所述;（ii）主要通过chlatrin介导的内吞作用和脂筏内化，而ApoA-I优先被chlatrin包被的小凹和巨胞饮内化，并且（iii）被蛋白酶体和溶酶体快速降解，而ApoA-I与再循环内体部分共定位。反之亦然，发现通过[1-93]ApoA-I的体外聚集获得的淀粉样原纤维不能进入细胞。我们认为[1-93]ApoA-I的内化和细胞内降解可能使多肽偏离淀粉样纤维形成，并导致这种病理学特征的缓慢进展和迟发。
Apolipoprotein A-I (ApoA-I) is an extracellular lipid acceptor, whose role in cholesterol efflux and high-density lipoprotein formation is mediated by ATP-binding cassette transporter A1 (ABCA1). Nevertheless, some ApoA-I variants are associated to systemic forms of amyloidosis, characterized by extracellular fibril deposition in peripheral organs. Heart amyloid fibrils were found to be mainly constituted by the 93-residue N-terminal fragment of ApoA-I, named [1-93]ApoA-I. In this paper, rat cardiomyoblasts were used as target cells to analyse binding, internalization and intracellular fate of the fibrillogenic polypeptide in comparison to full-length ApoA-I. We provide evidence that the polypeptide: (i) binds to specific sites on cell membrane (Kd= 5.90 +/- 0.70 x 10-7 M), where it partially co-localizes with ABCA1, as also described for ApoA-I; (ii) is internalized mostly by chlatrin-mediated endocytosis and lipid rafts, whereas ApoA-I is internalized preferentially by chlatrin-coated pits and macropinocytosis and (iii) is rapidly degraded by proteasome and lysosomes, whereas ApoA-I partially co-localizes with recycling endosomes. Vice versa, amyloid fibrils, obtained by in vitro aggregation of [1-93]ApoA-I, were found to be unable to enter the cells. We propose that internalization and intracellular degradation of [1-93]ApoA-I may divert the polypeptide from amyloid fibril formation and contribute to the slow progression and late onset that characterize this pathology.