Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
Nat Commun. 2012;3:1062. doi: 10.1038/ncomms2070.
Lysosomal storage diseases are a class of over 70 rare genetic diseases that are amenable to enzyme replacement therapy. Towards developing a plant-based enzyme replacement therapeutic for the lysosomal storage disease mucopolysaccharidosis I, here we expressed α-L-iduronidase in the endosperm of maize seeds by a previously uncharacterized mRNA-targeting-based mechanism. Immunolocalization, cellular fractionation and in situ RT-PCR demonstrate that the α-L-iduronidase protein and mRNA are targeted to endoplasmic reticulum (ER)-derived protein bodies and to protein body-ER regions, respectively, using regulatory (5'- and 3'-UTR) and signal-peptide coding sequences from the γ-zein gene. The maize α-L-iduronidase exhibits high activity, contains high-mannose N-glycans and is amenable to in vitro phosphorylation. This mRNA-based strategy is of widespread importance as plant N-glycan maturation is controlled and the therapeutic protein is generated in a native form. For our target enzyme, the N-glycan structures are appropriate for downstream processing, a prerequisite for its potential as a therapeutic protein.
溶酶体贮积症是一类 70 多种罕见的遗传性疾病，可采用酶替代疗法治疗。为了开发用于溶酶体贮积症黏多糖贮积症 I 的基于植物的酶替代治疗方法，我们通过以前未被描述的基于 mRNA 靶向的机制在玉米种子的胚乳中表达了α-L-艾杜糖苷酶。免疫定位、细胞分级分离和原位 RT-PCR 表明，α-L-艾杜糖苷酶蛋白和 mRNA 分别靶向内质网 (ER) 衍生的蛋白体和蛋白体-ER 区域，使用来自γ-zein 基因的调节（5'和 3'UTR）和信号肽编码序列。玉米α-L-艾杜糖苷酶表现出高活性，含有高甘露糖 N-聚糖，并且可进行体外磷酸化。这种基于 mRNA 的策略具有广泛的重要性，因为植物 N-聚糖成熟受到控制，并且治疗性蛋白质以天然形式产生。对于我们的靶酶，N-聚糖结构适合下游加工，这是其作为治疗性蛋白质的潜在用途的前提条件。
