Stathmin regulates centrosomal nucleation of microtubules and tubulin dimer/polymer partitioning.
Stathmin regulates centrosomal nucleation of microtubules and tubulin dimer/polymer partitioning.
复制标题
Stathmin 调节微管的中心体成核和微管蛋白二聚体/聚合物分配。
DOI：
10.1091/mbc.e09-02-0140
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发表时间：
2009
影响因子：
3.3
通讯作者：
Cassimeris,Lynne
中科院分区：
文献类型：
--
作者：
Ringhoff,DanielleN;Cassimeris,Lynne
Stathmin 是一种微管不稳定蛋白，在脊椎动物中普遍表达，并在许多癌症中高度表达。在几种细胞类型中，stathmin 调节微管蛋白在未组装形式和聚合物形式之间的分配，但负责分配的机制尚未确定。我们检查了两个细胞系统中的 stathmin 功能：从胚胎 +/+、+/- 和 -/− 中分离出 stathmin 基因的小鼠胚胎成纤维细胞 (MEF)，以及表达 Stathmin-青色荧光蛋白 (CFP) 或注射有 stathmin 蛋白的猪肾上皮 (LLCPK) 细胞。在MEF中，stathmin的相对量与基因型相对应，其中stathmin杂合的细胞表达的stathmin mRNA和蛋白质是野生型细胞的一半。 Stathmin 的减少或缺失导致微管聚合物增加，但细胞外围的微管动力学几乎没有变化。 LLCPK细胞中stathmin水平的增加足以降低微管密度，但允许微管保留在细胞外围，也没有对微管动力学产生重大影响。相反，stathmin 水平对中心体微管成核率有显着影响，其中较低的 Stathmin 水平增加成核，较高的 Stathmin 水平减少成核。依赖于 Stathmin 的成核调节仅在间期活跃； stathmin-CFP 的过表达不影响 LLCPK 细胞的中期微管成核率，并且 stathmin +/+ 和 -/− MEF 中的星形微管数量相似。这些数据支持一个模型，其中 stathmin 在间期发挥作用，通过设置每个细胞的微管数量来控制微管蛋白在二聚体和聚合物池之间的分配。
Stathmin is a microtubule-destabilizing protein ubiquitously expressed in vertebrates and highly expressed in many cancers. In several cell types, stathmin regulates the partitioning of tubulin between unassembled and polymer forms, but the mechanism responsible for partitioning has not been determined. We examined stathmin function in two cell systems: mouse embryonic fibroblasts (MEFs) isolated from embryos +/+, +/−, and −/− for the stathmin gene and porcine kidney epithelial (LLCPK) cells expressing stathmin-cyan fluorescent protein (CFP) or injected with stathmin protein. In MEFs, the relative amount of stathmin corresponded to genotype, where cells heterozygous for stathmin expressed half as much stathmin mRNA and protein as wild-type cells. Reduction or loss of stathmin resulted in increased microtubule polymer but little change to microtubule dynamics at the cell periphery. Increased stathmin level in LLCPK cells, sufficient to reduce microtubule density, but allowing microtubules to remain at the cell periphery, also did not have a major impact on microtubule dynamics. In contrast, stathmin level had a significant effect on microtubule nucleation rate from centrosomes, where lower stathmin levels increased nucleation and higher stathmin levels reduced nucleation. The stathmin-dependent regulation of nucleation is only active in interphase; overexpression of stathmin-CFP did not impact metaphase microtubule nucleation rate in LLCPK cells and the number of astral microtubules was similar in stathmin +/+ and −/− MEFs. These data support a model in which stathmin functions in interphase to control the partitioning of tubulins between dimer and polymer pools by setting the number of microtubules per cell.