Nagaoka I, Hirata M, Sugimoto K, Tsutsumi-Ishii Y, Someya A, Saionji K, Igari J
Department of Biochemistry, Juntendo University, School of Medicine, Tokyo, Japan.
J Leukoc Biol. 1998 Dec;64(6):845-52. doi: 10.1002/jlb.64.6.845.
To understand the gene expression of CAP18 (18-kDa cationic antibacterial protein), a member of cathelicidins, we evaluated mRNA and protein expression of CAP18 using human bone marrow cells and mature neutrophils. Northern blot analysis revealed that CAP18 mRNA was expressed more abundantly in bone marrow cells than mature neutrophils, whereas Western blot analysis indicated that CAP18 protein was more abundant in mature neutrophils than bone marrow cells. Consistent with this, in situ hybridization using bone marrow cells demonstrated that the expression of CAP18 mRNA was neutrophil lineage-specific and was observed primarily in myelocytes (>95%) with limited expression in more immature cells (promyelocytes) and mature cells (metamyelocytes, band cells, and segmented neutrophils). Furthermore, immunohistochemical study indicated that, coincident with the increase of CAP18 mRNA levels, CAP18-positive cells increased markedly at myelocyte stage, and the increased levels remained almost constant (>95%) in metamyelocytes, band cells, and segmented neutrophils, although the mRNA levels were remarkably reduced in these cells. Together these observations indicate that CAP18 gene transcription likely occurs lineage- and stage-specifically at the myelocyte stage of neutrophil maturation in the bone marrow and results in the synthesis and cytoplasmic accumulation of CAP18, which is present in the subsequent stages of neutrophil maturation.
为了解cathelicidins家族成员CAP18（18 kDa阳离子抗菌蛋白）的基因表达情况，我们利用人骨髓细胞和成熟中性粒细胞评估了CAP18的mRNA和蛋白表达。Northern印迹分析显示，CAP18 mRNA在骨髓细胞中的表达比成熟中性粒细胞更丰富，而Western印迹分析表明，CAP18蛋白在成熟中性粒细胞中比骨髓细胞更丰富。与此一致的是，利用骨髓细胞进行的原位杂交表明，CAP18 mRNA的表达具有中性粒细胞谱系特异性，主要在中幼粒细胞（>95%）中观察到，在更不成熟的细胞（早幼粒细胞）和成熟细胞（晚幼粒细胞、杆状核细胞和分叶核中性粒细胞）中表达有限。此外，免疫组织化学研究表明，与CAP18 mRNA水平的增加相一致，CAP18阳性细胞在中幼粒细胞阶段显著增加，并且在晚幼粒细胞、杆状核细胞和分叶核中性粒细胞中增加的水平几乎保持恒定（>95%），尽管这些细胞中的mRNA水平显著降低。这些观察结果共同表明，CAP18基因转录可能在骨髓中中性粒细胞成熟的中幼粒细胞阶段按谱系和阶段特异性发生，并导致CAP18的合成和细胞质积累，CAP18存在于中性粒细胞成熟的后续阶段。
