Tsai H M, Nagel R L, Hatcher V B, Seaton A C, Sussman I I
Division of Hematology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, New York 10467.
Br J Haematol. 1991 Oct;79(2):239-45. doi: 10.1111/j.1365-2141.1991.tb04528.x.
We have previously reported that two forms of von Willebrand factor (vWf) exist in cultured human umbilical vein endothelial cells: a high molecular weight (HMW) form that is released and can be proteolytically cleaved into a series of plasma-like multimers, and a non-secreted low molecular weight (LMW) form. In this study, the mode of vWf release and the relationship between the two forms were examined. As determined by two-dimensional analysis as well as by immunoreactivity with an antibody to the propolypeptide, the LMW form of endothelial cell vWf consisted of a 260 kD pro-vWf polypeptide, while the HMW form consisted of a 225 kD mature polypeptide. Only the 260 kD polypeptide was susceptible to digestion with endoglycosidase H. Release of the HMW form into the culture media was accompanied by a decrease in cellular vWf. Treatment of endothelial cells with cycloheximide or tunicamycin caused a decrease in the LMW form but did not affect the secretion of the HMW form. These results suggest that two pools of vWf exist in endothelial cells--a LMW form of pro-vWf in the endoplasmic reticulum and a HMW form of mature vWf in the storage compartment. Released vWf derives only from the storage pool.
我们之前报道过，在培养的人脐静脉内皮细胞中存在两种形式的血管性血友病因子（vWf）：一种是高分子量（HMW）形式，可被释放并能被蛋白水解切割成一系列类似血浆的多聚体；另一种是不分泌的低分子量（LMW）形式。在本研究中，我们检测了vWf的释放模式以及这两种形式之间的关系。通过二维分析以及与前体多肽抗体的免疫反应性测定，内皮细胞vWf的LMW形式由一条260 kD的前vWf多肽组成，而HMW形式由一条225 kD的成熟多肽组成。只有260 kD的多肽对内切糖苷酶H敏感。HMW形式释放到培养基中伴随着细胞内vWf的减少。用环己酰亚胺或衣霉素处理内皮细胞会导致LMW形式减少，但不影响HMW形式的分泌。这些结果表明，内皮细胞中存在两部分vWf——内质网中的前vWf的LMW形式和储存区室中的成熟vWf的HMW形式。释放的vWf仅来源于储存池。
