Department of Molecular Biology and Genetics, Istanbul Technical University, Istanbul, Turkey.
PLoS One. 2013 Jul 24;8(7):e69423. doi: 10.1371/journal.pone.0069423. Print 2013.
Katanin is an ATPase family member protein that participates in microtubule severing. It has heterodimeric structure consisting of 60 kDa (katanin-p60) and 80 kDa (katanin-p80) subunits encoded by KATNA1 and KATNB1 genes, respectively. Katanin-p60 has the enzymatic activity for microtubule severing, whereas katanin-p80 consists of multiple domains with different functions such as targeting katanin-p60 to the centrosome, augmenting microtubule severing by katanin-p60, and even suppressing microtubule severing. Despite the various important functions of katanin-p80, its transcriptional regulation has not been studied yet. Elk1 transcription factor has been shown to interact with microtubules and regulate the transcription of another microtubule severing protein, spastin. In spite of katanin's importance, and structural and functional similarities to spastin, there is no study on the transcriptional regulation of katanin yet. In this study, we aimed to characterize KATNB1 promoter and analyze the effects of Elk1 on katanin-p80 expression. We identified a 518- bp TATA-less promoter including a critical CpG island and GC boxes as an optimal promoter, and sequential deletion of CpG island and the GC elements gradually decreased the KATNB1 promoter activity. In addition, we showed Elk1 binding on the KATNB1 promoter by EMSA. We found that Elk1 activated KATNB1 promoter, and increased both mRNA and protein levels of katanin-p80 in SH-SY5Y cells. On the other hand, KCl treatment increasing SUMOylation decreased KATNB1 promoter activity. Since microtubule severing is an important cellular mechanism of which malfunctions result in serious diseases such as spastic paraplegia, Alzheimer's disease and cell cycle related disorders, identification of KATNB1 transcriptional regulation is crucial in understanding the coordination of microtubule severing activity by different proteins in the cells.
卡坦宁是一种 ATP 酶家族成员蛋白，参与微管切割。它具有异二聚体结构，由 KATNA1 和 KATNB1 基因分别编码 60 kDa（卡坦宁-p60）和 80 kDa（卡坦宁-p80）亚基。卡坦宁-p60 具有微管切割的酶活性，而卡坦宁-p80 由多个具有不同功能的结构域组成，例如将卡坦宁-p60 靶向中心体，增强卡坦宁-p60 的微管切割，甚至抑制微管切割。尽管卡坦宁-p80 具有多种重要功能，但它的转录调控尚未得到研究。Elk1 转录因子已被证明与微管相互作用，并调节另一种微管切割蛋白 spastin 的转录。尽管卡坦宁具有重要性，并且与 spastin 在结构和功能上具有相似性，但目前尚未对卡坦宁的转录调控进行研究。在这项研究中，我们旨在表征 KATNB1 启动子并分析 Elk1 对卡坦宁-p80 表达的影响。我们确定了一个包含关键 CpG 岛和 GC 盒的 518-bp TATA 缺失启动子作为最优启动子，并且 CpG 岛和 GC 元件的顺序缺失逐渐降低了 KATNB1 启动子活性。此外，我们通过 EMSA 显示 Elk1 结合在 KATNB1 启动子上。我们发现 Elk1 激活了 KATNB1 启动子，并在 SH-SY5Y 细胞中增加了卡坦宁-p80 的 mRNA 和蛋白水平。另一方面，KCl 处理增加 SUMOylation 降低了 KATNB1 启动子活性。由于微管切割是一种重要的细胞机制，其功能障碍会导致严重疾病，如痉挛性截瘫、阿尔茨海默病和细胞周期相关障碍，因此鉴定 KATNB1 的转录调控对于理解不同蛋白质在细胞中协调微管切割活性至关重要。
