Manipulating N-acetyl-L-aspartate transport to treat Canavan leukodystrophy

Canavan病是一种空泡型(海绵状)脑白质营养不良症，由ASPA突变引起 降低大脑天冬氨酸氨基转移酶的活性。目前这种神经退行性疾病的治疗方法， 包括饮食控制，服用柠檬酸锂和抗惊厥药物，以及 AAV介导的脑实质ASPA基因治疗不逆转或阻止进展 受影响婴儿和儿童的神经缺陷。 因为天冬氨酸酯酶是裂解脑内丰富的氨基酸N-乙酰-L所必需的。 天冬氨酸(NAA)、脑NAA在Canavan病中显著升高。我们是第一个报告的 敲除或敲除编码NAA合成酶的基因Nat81 N-乙酰转移酶8-样，通过以下方式防止运动障碍和脑空泡化的发展 天冬氨酸酯酶缺陷型卡那文病(“CD”)小鼠。后来，我们展示了鞘内 对幼年CD小鼠给予Nat81抑制反义寡核苷酸的逆转作用 他们已经确定的大脑NAA升高、运动障碍和大脑空泡化。合在一起，那些 结果有力地支持了加拿大人运动障碍和脑空泡化的假说 疾病是大脑NAA升高的后果。 我们在这份拨款申请中提出的最新研究表明，构成缺失的 编码NaDC3的Slc13a3，它是NAA和NAA的质膜钠偶联转运蛋白 其他二羧酸盐，使脑NAA含量正常化，防止共济失调和脑内空泡化 CD鼠。此外，我们已经证实了先前的报道，星形胶质细胞和肾脏近端小管 上皮细胞表达SLC13a3和NaDC3，并定位于脑膜NaDC3的表达。 蛛网膜下腔相关Prox1+细胞。 我们现在计划进行条件删除研究，以确定选择性消融NaDC3是否 星形胶质细胞(特异靶1)、蛛网膜(特异靶2)或肾近端小管上皮 (特定目标3)足以使大脑NAA含量正常化，扭转运动障碍和大脑 症状性CD小鼠的空泡化。这些研究的结果将有助于指导 SLC13a3和NaDC3选择性靶向治疗婴幼儿肺癌的研究 卡纳文病。

Canavan disease is a vacuolar (“spongiform”) leukodystrophy caused by ASPA mutations that diminish brain aspartoacylase activity. Current treatments for this neurodegenerative disorder, which include dietary manipulations, administration of lithium citrate and anticonvulsants, and AAV-mediated brain parenchymal ASPA gene therapy, do not reverse or prevent progression of neurological deficits in affected infants and children. Because aspartoacylase is necessary for cleavage of the abundant brain amino acid N-acetyl-L- aspartate (NAA), brain NAA is markedly elevated in Canavan disease. We were the first to report that knocking out or knocking down Nat8l, the gene that encodes the NAA-synthesizing enzyme N-acetytransferase 8-like, prevented development of motor deficits and brain vacuolation by aspartoacylase-deficient Canavan disease (“CD”) mice. Later, we showed that intrathecal administration of an Nat8l-inhibiting antisense oligonucleotide to young adult CD mice reversed their established brain NAA elevation, motor deficits and brain vacuolation. Together, those results strongly support the hypothesis that motor deficits and brain vacuolation in Canavan disease are consequences of elevated brain NAA. Our most recent studies, presented in this grant application, indicate that constitutive deletion of Slc13a3, which encodes NaDC3, a plasma membrane sodium-coupled transporter for NAA and other dicarboxylates, normalizes brain NAA content and prevents ataxia and brain vacuolation in CD mice. Also, we have confirmed prior reports that astroglia and renal proximal tubular epithelium express Slc13a3 and NaDC3, and have localized meningeal NaDC3 expression to arachnoid mater-associated Prox1+ cells. We now plan conditional deletion studies to determine whether selective ablation of NaDC3 from astroglia (Specific Aim 1), arachnoid (Specific Aim 2), or renal proximal tubular epithelium (Specific Aim 3) is sufficient to normalize brain NAA content and reverse motor deficits and brain vacuolation in symptomatic CD mice. Results of these studies will serve to guide development of selective Slc13a3 and NaDC3 therapeutic targeting strategies for infants and children with Canavan disease.