Boehmerle Wolfgang, Splittgerber Ute, Lazarus Michael B, McKenzie Kathleen M, Johnston David G, Austin David J, Ehrlich Barbara E
Department of Pharmacology, Yale University, New Haven, CT 06520, USA.
Proc Natl Acad Sci U S A. 2006 Nov 28;103(48):18356-61. doi: 10.1073/pnas.0607240103. Epub 2006 Nov 17.
Taxol (Paclitaxel) is an important natural product for the treatment of solid tumors. Despite a well documented tubulin-stabilizing effect, many side effects of taxol therapy cannot be explained by cytoskeletal mechanisms. In the present study submicromolar concentrations of taxol, mimicking concentrations found in patients, induced cytosolic calcium (Ca(2+)) oscillations in a human neuronal cell line. These oscillations were independent of extracellular and mitochondrial Ca(2+) but dependent on intact signaling via the phosphoinositide signaling pathway. We identified a taxol binding protein, neuronal Ca(2+) sensor 1 (NCS-1), a Ca(2+) binding protein that interacts with the inositol 1,4,5-trisphosphate receptor from a human brain cDNA phage display library. Taxol increased binding of NCS-1 to the inositol 1,4,5-trisphosphate receptor. Short hairpin RNA-mediated knockdown of NCS-1 in the same cell line abrogated the response to taxol but not to other agonists stimulating the phosphoinositide signaling pathway. These findings are important for studies involving taxol as a research tool in cell biology and may help to devise new strategies for the management of side effects induced by taxol therapy.
紫杉醇是治疗实体瘤的一种重要天然产物。尽管紫杉醇具有稳定微管蛋白的作用已得到充分证明，但紫杉醇治疗的许多副作用无法用细胞骨架机制来解释。在本研究中，模仿患者体内发现的浓度的亚微摩尔浓度紫杉醇，在人神经细胞系中诱导了胞质钙（Ca(2+)）振荡。这些振荡独立于细胞外和线粒体Ca(2+)，但依赖于通过磷脂酰肌醇信号通路的完整信号传导。我们从人脑cDNA噬菌体展示文库中鉴定出一种紫杉醇结合蛋白，神经元钙（Ca(2+)）传感器1（NCS-1），一种与肌醇1,4,5-三磷酸受体相互作用的Ca(2+)结合蛋白。紫杉醇增加了NCS-1与肌醇1,4,5-三磷酸受体的结合。在同一细胞系中，短发夹RNA介导的NCS-1敲低消除了对紫杉醇的反应，但对刺激磷脂酰肌醇信号通路的其他激动剂没有影响。这些发现对于将紫杉醇用作细胞生物学研究工具的研究很重要，并且可能有助于设计新的策略来管理紫杉醇治疗引起的副作用。
