Regulation of Reduced Folate Carrier (RFC) by Vitamin D Receptor at the Blood-Brain Barrier.
Regulation of Reduced Folate Carrier (RFC) by Vitamin D Receptor at the Blood-Brain Barrier.
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DOI：
10.1021/acs.molpharmaceut.7b00572
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发表时间：
2017-11-06
影响因子：
4.9
通讯作者：
Bendayan R
中科院分区：
文献类型：
--
作者：
Alam C;Hoque MT;Finnell RH;Goldman ID;Bendayan R
叶酸对大脑发育和功能至关重要。哺乳动物组织中的叶酸转运由三种主要的叶酸转运系统介导，即，还原叶酸载体（RFC）、质子偶联叶酸转运蛋白（PCFT）和叶酸受体α（FRα），已知受配体激活的核受体（如维生素D受体（VDR））调节。叶酸在脉络丛的摄取需要FRα和PCFT的作用，对脑叶酸递送至关重要。失活FRα或PCFT突变导致严重的脑叶酸缺乏，导致儿童早期神经退行性变。本研究的目的是研究RFC在血脑屏障（BBB）水平上对叶酸摄取的作用及其可能的VDR调节。我们在不同的体外BBB模型系统中检测到RFC的稳健表达，特别是在人脑微血管内皮细胞（hCMEC/D3）和分离的小鼠脑毛细血管的永生化培养物中。pH7.4时hCMEC/D3细胞对[3 H]-甲氨蝶呤的摄取被PT 523和培美曲塞（对RFC具有高亲和力的叶酸拮抗剂）抑制。我们还发现，通过骨化三醇（1，25-二羟基维生素D3）暴露激活VDR上调RFC mRNA和蛋白质表达以及hCMEC/D3细胞和分离的小鼠脑毛细血管中的功能。我们进一步证明了RFC表达可以通过VDR靶向siRNA下调，进一步证实了VDR在直接调节叶酸转运蛋白中的作用。总之，这些数据表明，增加RFC功能表达可能构成一种新的策略，用于增强脑叶酸输送，治疗FRα或PCFT功能丧失引起的神经代谢紊乱。
Folates are essential for brain development and function. Folate transport in mammalian tissues is mediated by three major folate transport systems, i.e., reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptor alpha (FRα), known to be regulated by ligand-activated nuclear receptors, such as vitamin D receptor (VDR). Folate uptake at the choroid plexus, which requires the actions of both FRα and PCFT, is critical to cerebral folate delivery. Inactivating FRα or PCFT mutations cause severe cerebral folate deficiency resulting in early childhood neurodegeneration. The objective of this study was to investigate the role of RFC in folate uptake at the level of the blood-brain barrier (BBB) and its potential regulation by VDR. We detected robust expression of RFC in different in vitro BBB model systems, particularly in immortalized cultures of human cerebral microvascular endothelial cells (hCMEC/D3) and isolated mouse brain capillaries. [3H]-methotrexate uptake by hCMEC/D3 cells at pH 7.4 was inhibited by PT523 and pemetrexed, antifolates with high affinity for RFC. We also showed that activation of VDR through calcitriol (1,25-dihydroxyvitamin D3) exposure up-regulates RFC mRNA and protein expression as well as function in hCMEC/D3 cells and isolated mouse brain capillaries. We further demonstrated that RFC expression could be down-regulated by VDR-targeting siRNA, further confirming the role of VDR in the direct regulation of this folate transporter. Together, these data suggest that augmenting RFC functional expression could constitute a novel strategy for enhancing brain folate delivery for the treatment of neurometabolic disorders caused by loss of FRα or PCFT function.
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影响因子：
4.7
作者：
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通讯作者：
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影响因子：
16.2
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影响因子：
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