Studies on Perxisome Biogenesis and Function of Pex1p

在这项科学研究资助11680608的支持下，我们获得了以下发现：过氧化物酶体生物发生障碍（PBDs），包括Zellweger综合征（ZS）和新生儿肾上腺白质营养不良（NALD）和婴儿Refsum病（IRD），是由过氧化物酶体组装缺陷和过氧化物酶体功能障碍引起的致命性常染色体隐性疾病，其中已报道了12种基因型。ZS患者表现出最严重的临床和生化异常，而NALD和IRD患者分别表现出较轻和较轻的特征。然而，很少有人关注在分子水平上确定最严重的ZS （NALD）和最轻微的IRD （IRD）在临床特征的不同严重程度之间的表型-基因型关系。我们通过对中国仓鼠卵巢突变细胞系ZP107过氧化物酶体缺陷的功能性互补，分离出了人PEX1 cDNA （HsPEX1）。PEX1是PBD发病率最高的补体多血组E （CG-E，美国/欧盟为CG1）的致病基因，编码过氧化物Pex1p，是aaa - atp酶蛋白家族的成员。我们之前报道过，温度敏感的过氧化物酶体组装是导致IRD临床特征温和的原因。也有报道称，Pex1p和Pex6p相互作用。在目前的工作中，我们研究了CG1 pbd的表型-基因型关系。来自IRD的Pex1p，如常被鉴定为G843D的Pex1p，在37℃的条件下，大部分在体内被降解，而在30℃的允许温度下，Pex1p在正常水平上可以被检测到。相比之下，来自ZS患者衍生的PEX蛋白的Pex1p，包括L664P突变或634-690氨基酸残基缺失的Pex1p，在两种温度下都稳定存在。Pex1p- g843d与Pex6p的相互作用水平为正常Pex1p的50%，而ZS患者的Pex1p表现出非温度敏感的过氧化物酶体生物发生几乎与Pex6p结合。综上所述，Pex1p的稳定性很可能反映了IRD成纤维细胞中温度敏感的过氧化物酶体组装。Pex1p-Pex6p相互作用失败会导致ZS中更严重的异常。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