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

Canavan病是一种空泡性（“海绵状”）脑白质营养不良，由ASPA突变引起， 降低脑内腺苷酰化酶活性。目前对这种神经退行性疾病的治疗， 包括饮食控制、给予柠檬酸锂和抗惊厥药， AAV介导的脑实质ASPA基因治疗，不逆转或阻止 受影响的婴儿和儿童的神经缺陷。 因为N-乙酰基-L-乙酰基酰化酶是切割大脑中丰富的氨基酸N-乙酰基-L- 天冬氨酸（NAA），脑NAA在Canavan病中显著升高。我们是第一个报道 敲除或敲低编码NAA合成酶的基因Nat 8l， N-乙酰转移酶8样，防止运动缺陷和脑空泡化的发展， 图10是示出了在患有Canavan病（“CD”）的小鼠中的一种或更多种小鼠中的一种或更多种的图。后来，我们发现鞘内注射 向年轻成年CD小鼠施用抑制Nat 8l的反义寡核苷酸逆转了 他们的大脑NAA升高，运动缺陷和脑空泡化。在一起，这些 结果强烈支持这一假设，即运动缺陷和脑空泡化在卡纳万 疾病是大脑NAA升高的结果。 我们最近的研究，在这个赠款申请中提出，表明组成性缺失， Slc 13 a3编码NaDC 3，一种质膜钠偶联的NAA转运蛋白， 其他二羧酸盐，使大脑NAA含量正常化，防止共济失调和脑空泡形成， CD老鼠此外，我们已经证实了先前的报告，星形胶质细胞和肾近端小管， 上皮表达Slc 13 a3和NaDC 3，并具有局部脑膜NaDC 3表达， 蛛网膜基质相关的Prox 1+细胞。 我们现在计划进行条件性缺失研究，以确定选择性消融NaDC 3是否能从 星形胶质细胞（特定目的1）、蛛网膜（特定目的2）或肾近端肾小管上皮细胞 （特定目标3）足以使大脑NAA含量正常化并逆转运动缺陷和大脑 在有症状的CD小鼠中空泡化。这些研究的结果将指导 选择性Slc 13 a3和NaDC 3治疗靶向策略，用于患有 卡纳万病

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.