Studies on Perxisome Biogenesis and Function of Pex1p

在11680608年度科学研究资助计划的支持下，我们取得了以下研究成果：过氧化体生物发生障碍(PBDS)，包括Zellweger综合征(ZS)、新生儿肾上腺脑白质营养不良(NALD)和婴儿Refsum病(IRD)，是由过氧化体组装缺陷和过氧化体功能障碍引起的致死性常染色体隐性遗传病，已报道了12种基因类型。ZS患者表现出最严重的临床和生化异常，而NALD和IRD患者分别表现出最轻和最轻的特征。然而，在分子水平上确定最严重的ZS(NALD)和最轻的IRD(IRD)之间临床特征的不同严重程度之间的表型-基因型关系还很少。我们通过功能互补中国仓鼠卵巢细胞系ZP107的过氧化物酶缺乏症，分离到了一个人PEX1基因(HsPEX1)。PEX1基因是补体…多项缺陷的致病基因E组(CG-E；美国/欧盟CG1)是发病率最高的PBD，其编码的Pex1p是AAA-ATPase蛋白家族的成员之一。我们早些时候报道过，温度敏感的过氧化酶体组装是导致IRD临床特征温和的原因。还有报道称，Pex1p和Pex6p相互作用。在目前的工作中，我们研究了CG1PBD的表型-基因型关系。来自IRD的Pex1p，如Pex1p和常见的G843D，在37℃时大部分在体内降解，而在允许温度下可检测到正常水平，30℃。相比之下，来自ZS患者来源的PEX蛋白的Pex1p，包括L664P处的突变或634-690处氨基酸残基的缺失，在两种温度下都稳定存在。Pex1p-G843D在正常Pex1p的50%水平上与Pex6p相互作用，而来自ZS患者的Pex1p几乎不与Pex6p结合。综上所述，Pex1p的稳定性很可能反映了IRD成纤维细胞对温度敏感的过氧化酶体组装。Pex1p-Pex6p相互作用失败导致更严重的异常，在ZS显着。较少

With the support of this Grants-in Aid for Scientific Research 11680608, we obtained following findings :The peroxisome biogenesis disorders (PBDs), including Zellweger syndrome (ZS) and neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD), are fatal autosomal recessive diseases caused by defects in peroxisome assembly as well as malfunction of peroxisomes, where 12 genotypes have been reported. ZS patients manifest the severest clinical and biochemical abnormalities, while those with NALD and IRD show the less severity and the mildest features, respectively. However, little attention has been paid to determining at the molecular level the phenotype-genotype relationships for the variable severity in clinical features between the severest ZS, NALD, and the mildest, IRD.We have isolated a human PEX1 cDNA (HsPEX1) by functional complementation of peroxisome deficiency of a mutant Chinese hamster ovary cell line, ZP107. PEX1 is the causative gene for PBDs of complementa … More tion group E (CG-E ; CG1 in USA/EU), the highest incidence PBD, and encodes the peroxin, Pex1p, a member of AAA-ATPase protein family. We earlier reported that temperature-sensitive peroxisome assembly is responsible for the mildness of the clinical features of IRD.It has been also reported that Pex1p and Pex6p interact with each other. In the present work, we investigated phenotype-genotype relationships of CG1 PBDs. Pex1p from IRD such as Pex1p with the frequently identified G843D was mostly degraded in vivo at 37℃, while it was detectable at a normal level in permissive temperature, 30℃. In contrast, Pex1p from ZS patients-derived PEX proteins, including each with a mutation at L664P or a deletion of amino acid residues at 634-690 were stably present at both temperatures. Pex1p-G843D interacted with Pex6p at 50% level of normal Pex1p, whilst Pex1p from ZS patients showing non-temperature-sensitive peroxisome biogenesis barely bound to Pex6p. Taken together, it is most likely that the stability of Pex1p reflects temperature-sensitive peroxisome assembly in IRD fibroblasts. Failure in Pex1p-Pex6p interaction gives rise to more severe abnormalities notable in ZS. Less