Ku86 exists as both a full-length and a protease-sensitive natural variant in multiple myeloma cells
Ku86 exists as both a full-length and a protease-sensitive natural variant in multiple myeloma cells
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DOI：
10.1186/1475-2867-8-4
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发表时间：
2008-01-01
影响因子：
5.8
通讯作者：
Teoh, Gerrard
中科院分区：
文献类型：
--
作者：
Gullo, Charles A.;Ge, Feng;Teoh, Gerrard
背景：Ku 86蛋白的截短变体先前已在86%至100%的新鲜分离的患者多发性骨髓瘤（MM）细胞中检测到。由于Ku 70/Ku 86异源二聚体作为DNA修复酶、DNA依赖性蛋白激酶的调节亚基发挥作用，我们一直对Ku 86变体（Ku 86 v）蛋白在MM基因组维持中的改变的表达和功能感兴趣。虽然，许多研究表明，Ku蛋白的截短形式可以通过体外人淋巴细胞中的蛋白水解降解人工产生，我们现在使用全细胞免疫印迹显示，RPMI-8226和SGH-MM 5人MM细胞系一致地表达全长Ku 86以及69-kDa Ku 86 v;一种C-末端截短的69-kDa变体Ku 86蛋白。与此相反，Ku 86 v蛋白没有检测到新鲜分离的淋巴细胞，如以前报道的。数据还表明，Ku 86 v不是作为碳水化合物修饰的结果产生的，但丝氨酸蛋白酶可能会作用于全长形式的protein.Conclusion：这些数据证实，MM细胞含有真正的Ku 86 v蛋白质，产生细胞内的转录后机制，这需要蛋白水解加工。
Background: Truncated variants of Ku86 protein have previously been detected in 86% to 100% of freshly isolated patient multiple myeloma (MM) cells. Since, the Ku70/Ku86 heterodimer functions as the regulatory subunit of the DNA repair enzyme, DNA-dependent protein kinase, we have been interested in the altered expression and function of Ku86 variant (Ku86v) proteins in genome maintenance of MM.Results: Although, a number of studies have suggested that truncated forms of Ku proteins could be artificially generated by proteolytic degradation in vitro in human lymphocytes, we now show using whole cell immunoblotting that the RPMI-8226 and SGH-MM5 human MM cell lines consistently express full-length Ku86 as well as a 69-kDa Ku86v; a C-terminus truncated 69-kDa variant Ku86 protein. In contrast, Ku86v proteins were not detected in the freshly isolated lymphocytes as was previously reported. Data also indicates that the Ku86v was not generated as a result of carbohydrate modification but that serine proteases may act on the full-length form of the protein.Conclusion: These data confirm that MM cells contain bona fide Ku86v proteins that were generated intracellularly by a post-transcriptional mechanism, which required proteolytic processing.