Amity Institute of Biotechnology, Amity University, Kolkata, India.
Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata, India.
Metallomics. 2022 Apr 1;14(4). doi: 10.1093/mtomcs/mfac005.
Intracellular copper [Cu(I)] has been hypothesized to play role in the differentiation of the neurons. This necessitates understanding the role of Cu(I) not only in the neurons but also in the glia considering their anatomical proximity, contribution towards ion homeostasis, and neurodegeneration. In this study, we did a systematic investigation of the changes in the cellular copper homeostasis during neuronal and glial differentiation and the pathways triggered by them. Our study demonstrates increased mRNA for the plasma membrane copper transporter CTR1 leading to increased Cu(I) during the neuronal (PC-12) differentiation. ATP7A is retained in the trans-Golgi network (TGN) despite high Cu(I) demonstrating its utilization towards the neuronal differentiation. Intracellular copper triggers pathways essential for neurite generation and ERK1/2 activation during the neuronal differentiation. ERK1/2 activation also accompanies the differentiation of the foetal brain derived neuronal progenitor cells. The study demonstrates that ERK1/2 phosphorylation is essential for the viability of the neurons. In contrast, differentiated C-6 (glia) cells contain low intracellular copper and significant downregulation of the ERK1/2 phosphorylation demonstrating that ERK1/2 activation does not regulate the viability of the glia. But ATP7A shows vesicular localization despite low copper in the glia. In addition to the TGN, ATP7A localizes into RAB11 positive recycling endosomes in the glial neurites. Our study demonstrates the role of copper dependent ERK1/2 phosphorylation in the neuronal viability. Whereas glial differentiation largely involves sequestration of Cu(I) into the endosomes potentially (i) for ready release and (ii) rendering cytosolic copper unavailable for pathways like the ERK1/2 activation.
细胞内铜 [Cu(I)] 被假设在神经元分化中发挥作用。这就需要不仅在神经元中，而且在神经胶质细胞中理解 Cu(I) 的作用，因为它们在解剖学上接近，对离子稳态的贡献，以及神经退行性变。在这项研究中，我们系统地研究了神经元和神经胶质细胞分化过程中细胞内铜稳态的变化，以及它们引发的途径。我们的研究表明，在神经元（PC-12）分化过程中，质膜铜转运蛋白 CTR1 的 mRNA 增加，导致 Cu(I) 增加。尽管铜（I）含量高，但 ATP7A 仍保留在反式高尔基网络 (TGN) 中，表明其用于神经元分化。细胞内铜触发了神经元分化过程中神经突生成和 ERK1/2 激活所必需的途径。ERK1/2 激活也伴随着胎儿脑源性神经元祖细胞的分化。该研究表明，ERK1/2 磷酸化对于神经元的活力是必不可少的。相反，分化的 C-6（神经胶质）细胞内含有低水平的铜，并且 ERK1/2 磷酸化的显著下调表明 ERK1/2 激活不会调节神经胶质的活力。但是，尽管在神经胶质细胞中铜含量低，但 ATP7A 仍表现出囊泡定位。除了 TGN 之外，ATP7A 还定位于神经胶质细胞突起中的 RAB11 阳性再循环内体中。我们的研究表明，铜依赖性 ERK1/2 磷酸化在神经元活力中起作用。而神经胶质分化在很大程度上涉及将 Cu(I) 隔离到内体中，可能是为了（i）随时释放，以及（ii）使细胞质铜无法用于 ERK1/2 激活等途径。
