Variant in C-terminal region of intestinal alkaline phosphatase associated with benign familial hyperphosphatasaemia.
Variant in C-terminal region of intestinal alkaline phosphatase associated with benign familial hyperphosphatasaemia.
复制标题
肠道碱性磷酸酶 C 末端区域的变异与良性家族性高磷酸酶血症相关。
DOI：
10.1136/jmedgenet-2017-104964
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发表时间：
2018
影响因子：
4
通讯作者：
Nomura F
中科院分区：
文献类型：
--
作者：
Ishige T;Itoga S;Utsuno E;Nishimura M;Yoshikawa M;Kato N;Matsushita K;Yokosuka O;Nomura F
背景良性家族性高磷酸酶血症很少进行基因诊断，分子机制很大程度上仍不清楚。目的我们遇到一例良性家族性肠碱性磷酸酶(IAP)高磷酸酶血症病例。为了阐明其分子机制，我们进行了ALPI基因测序和体外蛋白表达分析。方法采用长链PCR和大规模平行测序对ALPI基因进行测序。通过糖基磷脂酰肌醇 (GPI) 裂解测定分析转染野生型或变体型 ALPI 基因的培养细胞系的可溶性和膜结合 ALP 活性。结果我们在 ALPI 基因的 C 末端发现了一个缺失-插入变体。该变异导致 IAP 的 GPI 锚定信号疏水性减弱。体外GPI切割实验表明，在变体IAP中，膜结合IAP大大减少，而可溶性IAP增加。结论ALPI中C端变体通过膜结合能力减弱，导致IAP良性家族性高磷酸酶血症。
BackgroundA genetic diagnosis has been rarely performed in benign familial hyperphosphatasaemia, and molecular mechanism largely remains unclear.ObjectivesWe encountered a case with benign familial hyperphosphatasaemia of intestinal alkaline phosphatase (IAP). To elucidate the molecular mechanism, we performedALPIgene sequencing and in vitro protein expression analysis.MethodsALPIgene was sequenced by long-range PCR and massively parallel sequencing. The soluble and membrane-bound ALP activities of the cultured cell line, transfected with the wild-type or variant-typeALPIgene were analysed by a glycosylphosphatidylinositol (GPI)-cleaving assay.ResultsWe identified a deletion–insertion variant in the C-terminal end of theALPIgene. This variant causes the attenuation of the hydrophobicity in GPI-anchor signal of IAP. An in vitro GPI-cleaving assay demonstrated that the membrane-bound IAP was greatly decreased, whereas the soluble IAP was increased, in the variant IAP.ConclusionsThe C-terminal variant inALPIcauses the benign familial hyperphosphatasaemia of IAP by the attenuation of the membrane-binding capability.