Jack R M, Fearon D T
Department of Medicine, Harvard Medical School, Boston, MA 02115.
J Immunol. 1988 Jun 15;140(12):4286-93.
Human peripheral blood polymorphonuclear neutrophils (PMN) have been considered to be capable of little if any protein biosynthesis. We evaluated the ability of PMN to synthesize both mRNA and proteins. Using in vitro [35S]methionine pulse-chase labeling of purified PMN, followed by immunoprecipitation of cell lysates with immobilized mAb and analysis by gel electrophoresis, PMN were shown to synthesize CR1, FcR, CR3 alpha-chain, MHC class I, and actin. In contrast, incorporation of [35S]methionine into either CR3 beta-chain or the secondary granule protein lactoferrin was not detected. Purification of mRNA from PMN and analysis by Northern blots demonstrated the presence in PMN of CR1, actin, and MHC class I transcripts. However, despite the apparent lack of CR3 beta-chain biosynthesis, specific beta-chain message was detectable in PMN RNA. Inhibition of mRNA synthesis in PMN with actinomycin D resulted in decreased synthesis of nascent CR1, FcR, MHC class I, and actin compared with control cells. Thus, PMN continue to transcribe and translate the genes for certain membrane and cytoskeletal proteins. In contrast, the lack of detectable synthesis of either lactoferrin or CR3 beta-chain suggested that biosynthesis in circulating PMN is selective.
人类外周血多形核中性粒细胞（PMN）一直被认为几乎没有蛋白质生物合成能力。我们评估了PMN合成mRNA和蛋白质的能力。通过对纯化的PMN进行体外[35S]甲硫氨酸脉冲追踪标记，随后用固定化单克隆抗体对细胞裂解物进行免疫沉淀并通过凝胶电泳分析，结果显示PMN能够合成CR1、FcR、CR3α链、MHC I类分子和肌动蛋白。相比之下，未检测到[35S]甲硫氨酸掺入CR3β链或次级颗粒蛋白乳铁蛋白中。从PMN中纯化mRNA并通过Northern印迹分析表明，PMN中存在CR1、肌动蛋白和MHC I类分子的转录本。然而，尽管明显缺乏CR3β链生物合成，但在PMN RNA中可检测到特异性β链信息。与对照细胞相比，用放线菌素D抑制PMN中的mRNA合成导致新生CR1、FcR、MHC I类分子和肌动蛋白的合成减少。因此，PMN继续转录和翻译某些膜蛋白和细胞骨架蛋白的基因。相比之下，乳铁蛋白或CR3β链未检测到合成表明循环中的PMN生物合成具有选择性。
