Department of Metabolic and Endocrine Diseases, Netherlands Metabolomics Center, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands.
Cell Mol Life Sci. 2012 Jan;69(1):149-63. doi: 10.1007/s00018-011-0743-1. Epub 2011 Jun 11.
Menkes disease (MD) is an X-linked recessive disorder characterized by copper deficiency resulting in a diminished function of copper-dependent enzymes. Most MD patients die in early childhood, although mild forms of MD have also been described. A diversity of mutations in the gene encoding of the Golgi-resident copper-transporting P(1B)-type ATPase ATP7A underlies MD. To elucidate the molecular consequences of the ATP7A mutations, various mutations in ATP7A associated with distinct phenotypes of MD (L873R, C1000R, N1304S, and A1362D) were analyzed in detail. All mutants studied displayed changes in protein expression and intracellular localization parallel to a dramatic decline in their copper-transporting capacity compared to ATP7A the wild-type. We restored these observed defects in ATP7A mutant proteins by culturing the cells at 30°C, which improves the quality of protein folding, similar to that which as has recently has been demonstrated for misfolded ATP7B, a copper transporter homologous to ATP7A. Further, the effect of the canine copper toxicosis protein COMMD1 on ATP7A function was examined as COMMD1 has been shown to regulate the proteolysis of ATP7B proteins. Interestingly, in addition to adjusted growth temperature, binding of COMMD1 partially restored the expression, subcellular localization, and copper-exporting activities of the ATP7A mutants. However, no effect of pharmacological chaperones was observed. Together, the presented data might provide a new direction for developing therapies to improve the residual exporting activity of unstable ATP7A mutant proteins, and suggests a potential role for COMMD1 in this process.
Menkes 病（MD）是一种 X 连锁隐性疾病，其特征是铜缺乏导致铜依赖性酶的功能降低。大多数 MD 患者在幼儿期死亡，尽管也描述了轻度 MD 形式。编码高尔基体驻留铜转运 P（1B）-型 ATP 酶 ATP7A 的基因突变是 MD 的基础。为了阐明 ATP7A 突变的分子后果，详细分析了与 MD 不同表型相关的各种 ATP7A 突变（L873R、C1000R、N1304S 和 A1362D）。与野生型 ATP7A 相比，所有研究的突变体均显示蛋白表达和细胞内定位的变化，与铜转运能力的急剧下降平行。我们通过在 30°C 下培养细胞来恢复这些观察到的 ATP7A 突变蛋白缺陷，这类似于最近对与 ATP7A 同源的铜转运蛋白 ATP7B 的错误折叠蛋白的研究，改善了蛋白质折叠的质量。此外，还研究了犬铜中毒蛋白 COMMD1 对 ATP7A 功能的影响，因为 COMMD1 已被证明可调节 ATP7B 蛋白的蛋白酶解。有趣的是，除了调整生长温度外，COMMD1 的结合部分恢复了 ATP7A 突变体的表达、亚细胞定位和铜外排活性。然而，未观察到药理学伴侣的作用。总之，所提供的数据可能为开发改善不稳定 ATP7A 突变蛋白的残余外排活性的治疗方法提供新的方向，并表明 COMMD1 在该过程中可能发挥作用。
