Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Department of Physiology, School of Basic Medicine, Qingdao University, Qingdao 266071, China.
Institute of Brain Science and Disease, Qingdao University, Qingdao 266071, China.
Cells. 2023 Oct 25;12(21):2519. doi: 10.3390/cells12212519.
Impaired iron homeostasis has been proven to be one of the critical contributors to the pathology of Parkinson's disease (PD). Ferritin is considered an intracellular protein responsible for storing cytosolic iron. Recent studies have found that ferritin can be secreted from cells independent of the classical endoplasmic reticulum-Golgi system. However, the precise mechanisms underlying the secretion of ferritin in the brain were not elucidated. In the present study, we demonstrated that the primary cultured astrocytes do have the ability to secrete ferritin, which is enhanced by iron treatment. Increased ferritin secretion was accompanied by increased protein expression of ferritin response to iron stimulation. Further study showed that iron-induced expression and secretion of ferritin could be inhibited by CQ or 3-MA pretreatment. In addition, the knockdown of transient receptor potential mucolipin 1 (TRPML1) antagonized iron-induced ferritin secretion, accompanied by further increased intracellular protein levels of ferritin. Further study demonstrated that ferritin colocalized with LAMP1 in iron-treated astrocytes. On the contrary, ras-associated protein 27a (Rab27a) knockdown further enhanced iron-induced ferritin secretion and decreased intracellular protein levels of ferritin. Furthermore, we also showed that the secretory autophagy protein tripartite motif containing 16 (TRIM16) and sec22b decreased in iron-treated astrocytes. These results suggested that astrocytes might secrete ferritin via TRPML1-mediated exocytosis. This provides new evidence for the mechanisms underlying the secretion of ferritin in primary cultured astrocytes under a high iron environment.
铁稳态失衡已被证明是帕金森病（PD）发病机制的关键因素之一。铁蛋白被认为是一种负责储存细胞溶质铁的细胞内蛋白。最近的研究发现，铁蛋白可以独立于经典的内质网-高尔基体系统从细胞中分泌出来。然而，铁蛋白在大脑中的分泌的确切机制尚未阐明。在本研究中，我们证明原代培养的星形胶质细胞确实具有分泌铁蛋白的能力，而铁处理可以增强这种能力。铁蛋白分泌增加伴随着铁刺激下铁蛋白蛋白表达增加。进一步的研究表明，CQ 或 3-MA 预处理可以抑制铁诱导的铁蛋白表达和分泌。此外，瞬时受体电位 mucolipin 1（TRPML1）的敲低拮抗了铁诱导的铁蛋白分泌，同时细胞内铁蛋白蛋白水平进一步增加。进一步的研究表明，铁处理的星形胶质细胞中铁蛋白与 LAMP1 共定位。相反，ras 相关蛋白 27a（Rab27a）的敲低进一步增强了铁诱导的铁蛋白分泌，并降低了细胞内铁蛋白蛋白水平。此外，我们还表明，铁处理的星形胶质细胞中分泌自噬蛋白三部分包含 16 个（TRIM16）和 sec22b 减少。这些结果表明星形胶质细胞可能通过 TRPML1 介导的胞吐作用分泌铁蛋白。这为高铁环境下原代培养星形胶质细胞中铁蛋白分泌的机制提供了新的证据。
