Cell-selective gene expression comprises a critical element of many adeno-associated virus (AAV) vector-based gene therapies, and to date achieving this goal has focused on AAV capsid engineering, cell-specific promoters, or cell-specific enhancers. Recently, we discovered that the capsid of AAV9 exerts a differential influence on constitutive promoters of sufficient magnitude to alter cell type gene expression in the rat CNS. For AAV9 vectors chicken β-actin (CBA) promoter-driven gene expression exhibited a dominant neuronal gene expression in the rat striatum. Surprisingly, for otherwise identical AAV9 vectors, the truncated CBA hybrid (CBh) promoter shifted gene expression toward striatal oligodendrocytes. In contrast, AAV2 vector gene expression was restricted to striatal neurons, regardless of the constitutive promoter used. Furthermore, a six-glutamate residue insertion immediately after the VP2 start residue shifted CBA-driven cellular gene expression from neurons to oligodendrocytes. Conversely, a six-alanine insertion in the same AAV9 capsid region reversed the CBh-mediated oligodendrocyte expression back to neurons without changing AAV9 capsid access to oligodendrocytes. Given the preponderance of AAV9 in ongoing clinical trials and AAV capsid engineering, this AAV9 capsid-promoter interaction reveals a previously unknown novel contribution to cell-selective AAV-mediated gene expression in the CNS.

中文翻译：

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AAV衣壳-启动子相互作用决定了CNS细胞选择性基因的体内表达。

细胞选择性基因表达是许多基于腺相关病毒（AAV）载体的基因治疗的关键要素，迄今为止，实现这一目标的重点是AAV衣壳工程，细胞特异性启动子或细胞特异性增强子。最近，我们发现AAV9的衣壳对组成型启动子产生了不同的影响，该启动子的大小足以改变大鼠CNS中细胞类型基因的表达。对于AAV9载体，鸡β-肌动蛋白（CBA）启动子驱动的基因表达在大鼠纹状体中表现出显性神经元基因表达。令人惊讶的是，对于其他相同的AAV9载体，截短的CBA杂种（CBh）启动子使基因表达向纹状体少突胶质细胞转移。相反，无论使用哪种组成型启动子，AAV2载体基因的表达都限于纹状体神经元。此外，在VP2开始残基插入后立即插入6个谷氨酸残基将CBA驱动的细胞基因表达从神经元转移到少突胶质细胞。相反，在相同的AAV9衣壳区域插入六丙氨酸可使CBh介导的少突胶质细胞表达转回神经元，而不会改变AAV9衣壳对少突胶质细胞的访问。鉴于正在进行的临床试验和AAV衣壳工程中AAV9的优势，这种AAV9衣壳-启动子的相互作用揭示了中枢神经系统中对细胞选择性AAV介导的基因表达的未知贡献。在相同的AAV9衣壳区域中插入六丙氨酸可使CBh介导的少突胶质细胞表达转回到神经元，而不会改变AAV9衣壳对少突胶质细胞的访问。鉴于正在进行的临床试验和AAV衣壳工程中AAV9的优势，这种AAV9衣壳-启动子相互作用揭示了中枢神经系统中对细胞选择性AAV介导的基因表达的未知贡献。在相同的AAV9衣壳区域中插入六丙氨酸可使CBh介导的少突胶质细胞表达恢复为神经元，而不会改变AAV9衣壳对少突胶质细胞的访问。鉴于正在进行的临床试验和AAV衣壳工程中AAV9的优势，这种AAV9衣壳-启动子的相互作用揭示了中枢神经系统中对细胞选择性AAV介导的基因表达的未知贡献。