Epidermal lamellar granules transport different cargoes as distinct aggregates
Epidermal lamellar granules transport different cargoes as distinct aggregates
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DOI：
10.1111/j.0022-202x.2004.22515.x
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发表时间：
2004-05-01
影响因子：
6.5
通讯作者：
Iizuka, H
中科院分区：
文献类型：
--
作者：
Ishida-Yamamoto, A;Simon, M;Iizuka, H
在经典的透射电子显微镜下，表皮的片层状颗粒（LG）表现为离散的圆形或长方形颗粒，但最近的一项低温透射电子显微镜研究声称，片层状颗粒实际上是分支管状结构。LG含有各种各样的货物，包括脂质、水解酶和其他几种蛋白质。目前尚不清楚它们之间的表达时间是否有任何差异，以及它们是单独还是集体分类到颗粒中。为了解决这些问题，我们利用激光共聚焦扫描显微镜和免疫电镜研究了正常人表皮中糖基神经酰胺（GlcCer）、组织蛋白酶D （CatD）、角膜粘蛋白（Cdsn）、钾化因子（KLK）7和KLK8的表达。结果与模型一致，LG是分支管状结构的一部分。在这个结构中，所有的成分都表现为单独的聚集体。在反式高尔基网络（TGN）中，观察到含有GlcCer、Cdsn、KLK7和KLK8的球根状突起，以及小的cat阳性囊泡。这些分子被证明是被递送到颗粒状角质形成细胞的顶端区域。该研究为各种LG货物的顺序合成和独立贩运提供了强有力的证据，其中首次包括来自TGN的CatD和KLK8。
Lamellar granules (LG) of the epidermis appear as discrete round or oblong shaped granules in classical transmission electron micrographs, but a recent cryo-transmission electron microscopy study has claimed that LG are in fact branched tubular structures. LG contain various cargoes including lipids, hydrolytic enzymes, and several other proteins. It is not known whether there are any differences in the timing of expression among them and whether they are sorted into the granules individually or collectively. In order to address these questions, we studied the expression of glucosylceramides (GlcCer), cathepsin D (CatD), corneodesmosin (Cdsn), kallikrein (KLK)7, and KLK8 in normal human epidermis using confocal laser scanning microscopy and immunoelectron microscopy. The results were consistent with the model that LG are parts of a branched tubular structure. In this structure, all the components were shown to be distributed as separate aggregates. In the trans-Golgi network (TGN), bulbous protrusions containing GlcCer, Cdsn, KLK7 and KLK8, and small CatD-positive vesicles were observed. The molecules were shown to be delivered to the apical region of granular keratinocytes. This study provides strong evidence for the sequential synthesis and independent trafficking of various LG cargoes, including for the first time CatD and KLK8, from TGN.