Effects of ammonia on processing and secretion of precursor and mature lysosomal enzyme from macrophages of normal and pale ear mice: evidence for two distinct pathways.
Effects of ammonia on processing and secretion of precursor and mature lysosomal enzyme from macrophages of normal and pale ear mice: evidence for two distinct pathways.
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DOI：
10.1083/jcb.100.6.1894
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发表时间：
1985-06
期刊：
影响因子：
--
通讯作者：
Swank RT
中科院分区：
文献类型：
--
作者：
Brown JA;Novak EK;Swank RT
溶酶体酶已被证明是作为微粒体前体合成的，其被加工成位于溶酶体中的成熟酶。我们研究了氯化铵对小鼠巨噬细胞中两种溶酶体酶（β-葡萄糖醛酸酶和β-半乳糖苷酶）的细胞内加工和分泌的影响。根据脉冲放射性标记和分子量分析的记录，这种溶酶体药物在几个小时内引起前体酶和成熟酶形式的大量分泌。在处理的细胞中，前体酶加工和分泌的正常细胞内途径发生了改变。每种前体的一小部分缓慢地递送至溶酶体细胞器。大多数前体形式穿过高尔基体，经历碳水化合物部分的进一步加工，然后以类似于分泌蛋白的方式分泌。新合成的β-半乳糖苷酶前体分泌的滞后时间明显长于β-葡萄糖醛酸酶前体的分泌滞后时间。分泌的成熟酶的来源是溶酶体细胞器。来自苍耳突变体的巨噬细胞在成熟溶酶体酶的分泌方面明显缺乏，但分泌的前体形式正常。这些结果表明，氨处理的巨噬细胞含有两种不同的细胞内溶酶体酶分泌途径，并且在浅耳突变体中发生了溶酶体内容物释放的特定阻断。
Lysosomal enzymes have been shown to be synthesized as microsomal precursors, which are processed to mature enzymes located in lysosomes. We examined the effect of ammonium chloride on the intracellular processing and secretion of two lysosomal enzymes, beta-glucuronidase and beta-galactosidase, in mouse macrophages. This lysosomotropic drug caused extensive secretion of both precursor and mature enzyme forms within a few hours, as documented by pulse radiolabeling and molecular weight analysis. The normal intracellular route for processing and secretion of precursor enzyme was altered in treated cells. A small percentage of each precursor was delivered to the lysosomal organelle slowly. Most precursor forms traversed the Golgi apparatus, underwent further processing of carbohydrate moieties, and were then secreted in a manner similar to secretory proteins. The lag time for secretion of newly synthesized beta-galactosidase precursor was notably longer than that for the beta-glucuronidase precursor. The source of the secreted mature enzyme was the lysosomal organelle. Macrophages from the pale ear mutant were markedly deficient in secretion of mature lysosomal enzyme but secreted precursor forms normally. These results suggest that ammonia-treated macrophages contain two distinct intracellular pathways for secretion of lysosomal enzymes and that a specific block in the release of lysosomal contents occurs in the pale ear mutant.