Polyamine transport by mammalian cells and mitochondria - Role of antizyme and glycosaminoglycans
Polyamine transport by mammalian cells and mitochondria - Role of antizyme and glycosaminoglycans
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DOI：
10.1074/jbc.m505445200
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发表时间：
2005-12-30
影响因子：
4.8
通讯作者：
Igarashi, K
中科院分区：
文献类型：
--
作者：
Hoshino, K;Momiyama, E;Igarashi, K
用NIH 3 T3和FM 3A细胞及大鼠肝线粒体研究了抗酶（AZ）和糖胺聚糖在哺乳动物细胞和线粒体摄取多胺中的作用。由于AZ mRNA中存在两个起始密码子AUG，AZ合成为两种亚型（29和24.5 kDa）。大多数AZ以可从第二个AUG翻译的24.5-kDa形式存在，但来自第一个AUG的29-kDa AZ的一部分与线粒体相关，因为在第一个和第二个甲硫氨酸之间存在线粒体靶向信号。24.5 kDa亚型的优势主要是由于存在亚精胺和有利的序列背景下（Kozak序列）在第二起始密码子AUG。精胺摄取由NIH 3 T3细胞抑制29和24.5 kDa AZ，但大鼠肝线粒体的摄取不受任何形式的AZ的影响。由于线粒体对精胺的吸收会导致细胞色素c（一种细胞凋亡增强剂）的释放，因此我们寻找除AZ以外的线粒体精胺吸收抑制剂。Na+、K+和Mg 2+等阳离子是线粒体摄取的抑制剂。已有研究表明磷脂酰肌醇蛋白聚糖-1上的硫酸乙酰肝素在人胚肺成纤维细胞摄取精胺中起重要作用。肝素，而不是硫酸乙酰肝素，轻微抑制精胺摄取FM 3A细胞在Mg 2+和Ca 2+的情况下，但在生理条件下，Mg 2+和Ca 2+的存在下没有影响。
The role of antizyme (AZ) and glycosaminoglycans in polyamine uptake by mammalian cells and mitochondria was examined using NIH3T3 and FM3A cells and rat liver mitochondria. AZ is synthesized as two isoforms (29 and 24.5 kDa) due to the existence of two initiation codon AUGs in the AZ mRNA. Most AZ existed as the 24.5-kDa form translatable from the second AUG, but a portion of the 29-kDa AZ from the first AUG was associated with mitochondria because of the presence of a mitochondrial targeting signal between the first and the second methionine. The predominance of the 24.5-kDa isoform was mainly due to the presence of spermidine and a favorable sequence context (Kozak sequence) at the second initiation codon AUG. Spermine uptake by NIH3T3 cells was inhibited by both 29- and 24.5-kDa AZs, but uptake by rat liver mitochondria was not influenced by either form of AZ. Because spermine uptake by mitochondria caused a release of cytochrome c, an enhancer of apoptosis, we looked for inhibitors of mitochondrial spermine uptake other than AZ. Cations such as Na+, K+, and Mg2+ were inhibitors of the mitochondrial uptake. It has been reported that heparan sulfate on glypican-1 plays important roles in spermine uptake by human embryonic lung fibroblasts. Heparin, but not heparan sulfate, slightly inhibited spermine uptake by FM3A cells in the absence of Mg2+ and Ca2+ but had no effect under physiological conditions in the presence of Mg2+ and Ca2+.