Portugal Camila C, Socodato Renato, Canedo Teresa, Silva Cátia M, Martins Tânia, Coreixas Vivian S M, Loiola Erick C, Gess Burkhard, Röhr Dominik, Santiago Ana R, Young Peter, Minshall Richard D, Paes-de-Carvalho Roberto, Ambrósio António F, Relvas João B
Instituto de Investigação e Inovação em Saúde and Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208 4200-135 Porto, Portugal.
Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Health Sciences Campus, Azinhaga Santa Comba, 3000-548 Coimbra, Portugal.
Sci Signal. 2017 Mar 28;10(472):eaal2005. doi: 10.1126/scisignal.aal2005.
Vitamin C is essential for the development and function of the central nervous system (CNS). The plasma membrane sodium-vitamin C cotransporter 2 (SVCT2) is the primary mediator of vitamin C uptake in neurons. SVCT2 specifically transports ascorbate, the reduced form of vitamin C, which acts as a reducing agent. We demonstrated that ascorbate uptake through SVCT2 was critical for the homeostasis of microglia, the resident myeloid cells of the CNS that are essential for proper functioning of the nervous tissue. We found that depletion of SVCT2 from the plasma membrane triggered a proinflammatory phenotype in microglia and resulted in microglia activation. Src-mediated phosphorylation of caveolin-1 on Tyr in microglia induced the internalization of SVCT2. Ascorbate treatment, SVCT2 overexpression, or blocking SVCT2 internalization prevented the activation of microglia. Overall, our work demonstrates the importance of the ascorbate transport system for microglial homeostasis and hints that dysregulation of ascorbate transport might play a role in neurological disorders.
维生素C对中枢神经系统(CNS)的发育和功能至关重要。质膜钠-维生素C共转运蛋白2(SVCT2)是神经元中维生素C摄取的主要介质。SVCT2特异性转运维生素C的还原形式抗坏血酸,抗坏血酸作为一种还原剂。我们证明,通过SVCT2摄取抗坏血酸对小胶质细胞的稳态至关重要,小胶质细胞是中枢神经系统中驻留的髓样细胞,对神经组织的正常功能至关重要。我们发现,质膜上SVCT2的缺失会触发小胶质细胞的促炎表型,并导致小胶质细胞活化。Src介导的小胶质细胞中小窝蛋白-1酪氨酸磷酸化诱导了SVCT2的内化。抗坏血酸处理、SVCT2过表达或阻断SVCT2内化可防止小胶质细胞活化。总体而言,我们的工作证明了抗坏血酸转运系统对小胶质细胞稳态的重要性,并暗示抗坏血酸转运失调可能在神经系统疾病中起作用。