Regulation and processing of a precursor form of eosinophil granule major basic protein (ProMBP) in differentiating eosinophils.
Regulation and processing of a precursor form of eosinophil granule major basic protein (ProMBP) in differentiating eosinophils.
复制标题
DOI：
10.1182/blood.v92.2.623.414k32_623_631
复制
发表时间：
1998-07
期刊：
影响因子：
20.3
通讯作者：
P. Popken-Harris;J. Checkel;D. Loegering;B. Madden;M. Springett;G. Kephart;G. Gleich
中科院分区：
文献类型：
--
作者：
P. Popken-Harris;J. Checkel;D. Loegering;B. Madden;M. Springett;G. Kephart;G. Gleich
嗜酸性粒细胞颗粒主要碱性蛋白（MBP）的cDNA编码一个总长度为222个氨基酸的前原分子（preproMBP）。PreproMBP包括15个氨基酸的分泌前导序列、90个氨基酸的酸性原片段和117个氨基酸的碱性MBP部分。预测pI为3.9的原片段的功能尚不清楚，但它使proMBP具有整体酸性电荷。由于proMBP在成熟的嗜酸性粒细胞中没有发现，我们分析了培养24天的白细胞介素-5（IL-5）刺激的脐带干细胞中嗜酸性粒细胞的分化。通过免疫荧光，proMBP在第6天出现，并在第18天达到峰值，而MBP在第12至24天表现突出。到第6天，Western印迹检测到异质性糖基化33-kD proMBP;其表达峰值出现在第12天。Western印迹显示33-kD proMBP连续加工成18-kD中间体形式，最后加工成14-kD MBP。通过双标记免疫电子显微镜，proMBP主要定位于大的未凝聚的嗜酸性粒细胞颗粒，而MBP定位于含有凝聚的中央区域的颗粒。因此，proMBP可能表达和加工为颗粒凝聚在一个多步骤的过程中分化嗜酸性粒细胞的14 kD MBP。
The cDNA for eosinophil granule major basic protein (MBP) encodes a prepromolecule with a total length of 222 amino acids (preproMBP). PreproMBP includes a secretory leader of 15 amino acids, an acidic propiece of 90 amino acids, and a basic MBP portion of 117 amino acids. The function of the propiece, which has a predicted pI of 3.9, is unknown, but it gives proMBP an overall acidic charge. Because proMBP is not found in mature eosinophils, we analyzed eosinophil differentiation in interleukin-5 (IL-5)-stimulated umbilical cord stem cells cultured for 24 days. By immunofluorescence, proMBP appeared by day 6 and peaked on day 18, whereas MBP was prominent at days 12 to 24. By day 6, Western blots detected heterogeneous glycosylated 33-kD proMBP; its peak expression occurred on day 12. Western blots showed sequential processing of 33-kD proMBP to an 18-kD intermediate form and finally to 14-kD MBP. By dual label immunoelectron microscopy, proMBP was localized primarily to large uncondensed eosinophil granules, whereas MBP was localized to granules containing a condensed central area. Thus, proMBP is likely expressed and processed as the granule condenses in a multistep process to 14-kD MBP in differentiating eosinophils.