A Golgi-targeting fluorescent probe for labile Fe(ii) to reveal an abnormal cellular iron distribution induced by dysfunction of VPS35
A Golgi-targeting fluorescent probe for labile Fe(ii) to reveal an abnormal cellular iron distribution induced by dysfunction of VPS35
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DOI：
10.1039/c8sc04386h
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发表时间：
2019-02-07
期刊：
影响因子：
8.4
通讯作者：
Nagasawa, Hideko
中科院分区：
文献类型：
--
作者：
Hirayama, Tasuku;Inden, Masatoshi;Nagasawa, Hideko
铁参与了我们身体中许多重要的生理过程。然而，过量的铁是神经退行性疾病的致病因素，导致异常的氧化应激。二价金属转运蛋白1（DMT 1）是Fe（II）离子的主要转运蛋白。在内吞过程中，DMT 1通过trans-Golgi网络向细胞膜的细胞内递送部分地由包括液泡蛋白分选蛋白（VPS）的逆转录酶介导的蛋白分选系统调节。因此，与DMT 1一起，高尔基体作为细胞内Fe（II）离子的传递系统中的枢纽细胞器。VPS相关蛋白分选系统的功能障碍可诱导DMT 1向溶酶体伴随Fe（II）离子的异常递送。为了探索这个问题，我们开发了一种荧光探针，Gol-SiRhoNox，通过整合我们原来的基于N-氧化物的Fe（II）特异性化学开关，一种新的高尔基体定位的化学基序，和极性敏感的荧光支架，用于高尔基体特异性检测Fe（II）离子。我们的同步成像研究使用Gol-SiRhoNox和LysoRhoNox，以前开发的荧光探针溶酶体Fe（II），揭示了细胞内分布平衡的Fe（II）离子之间的高尔基体和溶酶体通常是高尔基体占主导地位，而溶酶体特异性升高的Fe（II）离子观察到在细胞诱导功能障碍的VPS 35，一个成员的retromer复杂。用R55（一种分子伴侣）处理功能失调的VPS 35细胞，导致Fe（II）离子的亚细胞分布恢复到高尔基体主导状态。这些结果表明，DMT 1交通机械的损害影响亚细胞铁稳态，促进Fe（II）泄漏在高尔基体和溶酶体积累的Fe（II）通过错误的DMT 1。
Iron is involved in numerous physiologically essential processes in our body. However, excessive iron is a pathogenic factor in neurodegenerative diseases, causing aberrant oxidative stress. Divalent metal transporter 1 (DMT1) acts as a primary transporter of Fe(II) ions. The intracellular delivery of DMT1 toward the cellular membrane via the trans-Golgi network during the endocytotic process is partially regulated by a retromer-mediated protein-sorting system comprising vacuolar protein-sorting proteins (VPSs). Thus, together with DMT1, the Golgi-apparatus acts as a hub organelle in the delivery system for intracellular Fe(II) ions. Dysfunction of the VPS-relevant protein sorting system can induce the abnormal delivery of DMT1 toward lysosomes concomitantly with Fe(II) ions. To explore this issue, we developed a fluorescent probe, Gol-SiRhoNox, for the Golgi-specific detection of Fe(II) ions by integrating our original N-oxide-based Fe(II)-specific chemical switch, a new Golgi-localizable chemical motif, and polarity-sensitive fluorogenic scaffold. Our synchronous imaging study using Gol-SiRhoNox and LysoRhoNox, a previously developed fluorescent probe for lysosomal Fe(II), revealed that the intracellular distribution balance of Fe(II) ions between the Golgi apparatus and lysosomes is normally Golgi-dominant, whereas the lysosome-specific elevation of Fe(II) ions was observed in cells with induced dysfunction of VPS35, a member of the retromer complex. Treatment of cells with dysfunctional VPS35 with R55, a molecular chaperone, resulted in the restoration of the subcellular distribution of Fe(II) ions to the Golgi-dominant state. These results indicate that the impairment of the DMT1 traffic machinery affects subcellular iron homeostasis, promoting Fe(II) leakage at the Golgi and lysosomal accumulation of Fe(II) through missorting of DMT1.