Kakigi Akinobu, Okada Teruhiko, Takeda Taizo, Uehara Natsumi, Nibu Ken-Ichi
Department of Otolaryngology-Head & Neck Surgery, Kobe University, Graduate School of Medicine, Hyogo, Japan.
Department of Anatomy, Kochi Medical School, Nankoku, Kochi, Japan.
Auris Nasus Larynx. 2019 Oct;46(5):790-796. doi: 10.1016/j.anl.2019.01.007. Epub 2019 Feb 8.
Objective The endocytosis of cationized feritin (CF) via a clathrin-mediated pathway is regulated by a signaling network. Marginal cells showed the active endocytosis of CF via a clathrin-mediated pathway. The internalization of receptors through this clathrin-mediated pathway is an important regulatory event in signal transduction. Numerous kinases are involved in endocytosis, and each endocytic route is subjected to high-order regulation by cellular signaling mechanisms. In this study, we investigated whether ROCK and MLCK signaling cascades and G-proteins regulate the endocytosis of CF in marginal cells of the stria vascularis. Methods CF was infused into the cochlear duct with pertussis toxin (PTX),Clostridium botulinum C3 toxin (BTX), guanosine(g-thio)-triphosphate (GTP-γS), ML-7, Y-27632. Endocytic activity was measured at 30 min after the start of infusion under an electron microscope. Results In marginal cells, CF was internalized via a clathrin-mediated pathway that depends on F-actin and microtubules (MT). Its processes were controlled by myosin light chain kinase (MLCK) and Rho-associated kinase (ROCK), but not affected by G-protein-coupled receptor (GPCR) or the RhoA signaling cascade. Conclusion Our previous study showed that the main endocytotic pathway of microperoxidase (MPO) did not depend on the Rho/ROCK molecular switch or actin/myosin motor system, but was mainly regulated by the RhoA signaling cascade. The present study results indicate that these signaling cascades regulating CF internalization completely differ from the cascades for MPO internalization.
目的 阳离子铁蛋白（CF）通过网格蛋白介导的途径进行的内吞作用受信号网络调控。边缘细胞显示出通过网格蛋白介导的途径对CF进行活跃的内吞作用。通过这种网格蛋白介导的途径使受体内化是信号转导中的一个重要调控事件。众多激酶参与内吞作用，并且每条内吞途径都受到细胞信号机制的高阶调控。在本研究中，我们调查了ROCK和MLCK信号级联以及G蛋白是否调节血管纹边缘细胞中CF的内吞作用。方法 将CF与百日咳毒素（PTX）、肉毒杆菌C3毒素（BTX）、鸟苷（γ-硫代）三磷酸（GTP-γS）、ML-7、Y-27632一起注入耳蜗管。在注入开始后30分钟，在电子显微镜下测量内吞活性。结果 在边缘细胞中，CF通过依赖于F-肌动蛋白和微管（MT）的网格蛋白介导的途径内化。其过程受肌球蛋白轻链激酶（MLCK）和Rho相关激酶（ROCK）控制，但不受G蛋白偶联受体（GPCR）或RhoA信号级联的影响。结论 我们之前的研究表明，微过氧化物酶（MPO）的主要内吞途径不依赖于Rho/ROCK分子开关或肌动蛋白/肌球蛋白运动系统，而是主要受RhoA信号级联调控。本研究结果表明，这些调节CF内化的信号级联与调节MPO内化的级联完全不同。
