Splitting and internalization of the desmosomes of cultured kidney epithelial cells by reduction in calcium concentration.
Splitting and internalization of the desmosomes of cultured kidney epithelial cells by reduction in calcium concentration.
复制标题
通过降低钙浓度来分裂和内化培养的肾上皮细胞的桥粒。
作者：
D. Mattey;D. Garrod
在维持在低钙培养基（LCM：[Ca 2 +]小于0.05 mM）中的简单上皮（MDBK和MDCK）细胞中，可以通过将[Ca 2 +]升高至标准培养基（SM：[Ca 2 +] = 1.8 mM）来诱导桥粒组装。在这里，它表明，如果SM中的细胞简单地返回LCM，其桥粒分裂在15分钟内的细胞间区域和桥粒的一半被内化在30分钟内。这是第一次，桥粒分裂已被证明发生在响应减少[Ca 2 +]，而不是Ca 2+螯合。荧光抗体染色显示，桥粒糖蛋白以及斑块成分被内化，尽管称为桥粒柯林斯的糖蛋白池仍然存在于细胞表面，显然与其他桥粒成分无关。桥粒的一半，最近已经内化响应LCM处理不返回到细胞表面参与新的桥粒形成。MDCK细胞能够快速（15-30分钟）形成新的桥粒，而旧的桥粒继续被内化。在SM中培养长达14天，MDBK细胞的桥粒对[Ca 2 +]减少的分裂和内化保持敏感。相反，在SM中4-5天后，MDCK细胞的桥粒变得对[Ca 2 +]的减少以及EGTA的Ca 2+螯合具有抗性。当用LCM或EGTA处理时，具有“稳定的”桥粒的MDCK细胞部分分离，但在某些点处保持彼此附着。附着区域被抗桥粒抗体染色，其特征是“巨大的”桥粒，长达4微米，大约是SM细胞中形成的桥粒的20倍。这些巨大的桥粒可能由小桥粒的侧向融合形成。
Desmosome assembly may be induced in simple epithelial (MDBK and MDCK) cells maintained in low calcium medium (LCM: [Ca2+] less than 0.05 mM) by raising [Ca2+] to that of standard culture medium (SM: [Ca2+] = 1.8 mM). Here it is shown that if cells in SM are simply returned to LCM, their desmosomes split in the intercellular region within 15 min and the desmosomal halves are internalized within 30 min. This is the first time that desmosome splitting has been shown to occur in response to a reduction in [Ca2+] rather than Ca2+ chelation. Fluorescent antibody staining shows that the desmosomal glycoproteins as well as the plaque constituents are internalized, although a pool of the glycoproteins known as desmocollins remains at the cell surface, apparently unassociated with other desmosomal components. Desmosomal halves that have been recently internalized in response to LCM treatment do not return to the cell surface to participate in new desmosome formation. MDCK cells are able to form new desmosomes rapidly (15-30 min) while old desmosomes continue to be internalized. The desmosomes of MDBK cells remain sensitive to splitting and internalization in response to reduction in [Ca2+] for up to 14 days of culture in SM. In contrast, the desmosomes of MDCK cells become resistant to reduction in [Ca2+], as well as Ca2+ chelation by EGTA, after 4-5 days in SM. When treated with LCM or EGTA, MDCK cells with 'stabilized' desmosomes partially separate but remain attached to each other at some points. Regions of attachment stain brightly with anti-desmosomal antibodies and are characterized by 'giant' desmosomes, up to 4 micron long, roughly 20 times larger than those formed in cells in SM. These giant desmosomes may form by lateral fusion of small desmosomes.