Christensen Rikke, Güttler Flemming, Jensen Thomas G
Department of Human Genetics, University of Aarhus, Denmark.
Mol Genet Metab. 2002 Aug;76(4):313-8. doi: 10.1016/s1096-7192(02)00101-4.
Phenylketonuria (PKU) is caused by deficiency of phenylalanine hydroxylase (PAH) and increased levels of phenylalanine. PAH requires the cofactor BH(4) to function and the rate-limiting step in the synthesis of BH(4) is GTP cyclohydrolase I (GTP-CH). The skin is a potential target tissue for PKU gene therapy. We have previously shown that overexpression of PAH and GTP-CH in primary human keratinocytes leads to high levels of phenylalanine clearance without BH(4) supplementation [Gene Ther. 7 (2000) 1971]. Here, we investigate the capacity of fibroblasts, another cell type from the skin, to metabolize phenylalanine. After retroviral gene transfer of PAH and GTP-CH both normal and PKU patient fibroblasts were able to metabolize phenylalanine, however, in lower amounts compared to genetically modified keratinocytes. Further comparative analyses between keratinocytes and fibroblasts revealed a higher copy number of transgenes in keratinocytes and also a higher metabolic capacity.
苯丙酮尿症（PKU）是由苯丙氨酸羟化酶（PAH）缺乏和苯丙氨酸水平升高引起的。PAH需要辅因子四氢生物蝶呤（BH(4)）来发挥作用，而BH(4)合成中的限速步骤是鸟苷三磷酸环化水解酶I（GTP-CH）。皮肤是PKU基因治疗的一个潜在靶组织。我们之前已经表明，在原代人角质形成细胞中过表达PAH和GTP-CH可在不补充BH(4)的情况下实现高水平的苯丙氨酸清除[《基因治疗》7（2000年）1971]。在此，我们研究皮肤的另一种细胞类型——成纤维细胞代谢苯丙氨酸的能力。在将PAH和GTP-CH进行逆转录病毒基因转移后，正常和PKU患者的成纤维细胞都能够代谢苯丙氨酸，然而，与基因修饰的角质形成细胞相比，代谢量较低。角质形成细胞和成纤维细胞之间的进一步比较分析显示，角质形成细胞中的转基因拷贝数更高，代谢能力也更强。
