AP1S1 missense mutations cause a congenital enteropathy via an epithelial barrier defect
AP1S1 missense mutations cause a congenital enteropathy via an epithelial barrier defect
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DOI：
10.1007/s00439-020-02168-w
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发表时间：
2020-04-18
期刊：
影响因子：
5.3
通讯作者：
Vogel, Georg F.
中科院分区：
文献类型：
--
作者：
Klee, Katharina M. C.;Janecke, Andreas R.;Vogel, Georg F.
先天性腹泻疾病（CDD）包括> 50种单基因实体，其特征在于早发性慢性腹泻，包括营养和电解质吸收、肠上皮细胞极化、肠内分泌细胞分化和上皮完整性的缺陷。腹泻也是许多免疫缺陷、先天性糖基化疾病和囊泡分选和转运机制缺陷的主要症状。我们通过全外显子组测序确定了2个近亲家族的难治性腹泻的病因，并确定了两个新的AP 1 S1突变，c.269T>C（p.Leu90Pro）和c.346G>A（p.Glu116Lys）。AP 1 S1编码衔接蛋白1复合物（AP-1）的小亚基，AP-1在网格蛋白被膜组装以及在高尔基体网络、内体和质膜之间的运输中起作用。产生CaCo 2肠细胞系的AP 1 S1敲除（KO）以表征肠AP 1 S1缺陷以及通过在KO背景中稳定表达鉴定的突变。亲代和KO细胞之间的形态学和原型转运蛋白分布相当。我们观察到紧密连接蛋白ZO-1和claudin 3的定位改变，跨上皮电阻降低，CaCo 2-AP 1 S1-KO单层的葡聚糖渗透性增加。此外，这些细胞的3D培养物中的管腔形成是异常的。野生型AP 1 S1在CaCo 2-AP 1 S1-KO细胞中的再表达恢复了这些异常，而含有任一错义突变的AP 1 S1的表达则没有。我们的数据表明，AP 1 S1功能的丧失导致肠上皮屏障缺陷，AP 1 S1突变可导致非综合征形式的先天性腹泻，而2例报告的截短AP 1 S1突变导致MEDNIK综合征，其特征为精神发育迟滞、肠病、耳聋、神经病、鱼鳞病和角皮病。
Congenital diarrheal disorders (CDD) comprise > 50 monogenic entities featuring chronic diarrhea of early-onset, including defects in nutrient and electrolyte absorption, enterocyte polarization, enteroendocrine cell differentiation, and epithelial integrity. Diarrhea is also a predominant symptom in many immunodeficiencies, congenital disorders of glycosylation, and in some defects of the vesicular sorting and transporting machinery. We set out to identify the etiology of an intractable diarrhea in 2 consanguineous families by whole-exome sequencing, and identified two novel AP1S1 mutations, c.269T>C (p.Leu90Pro) and c.346G>A (p.Glu116Lys). AP1S1 encodes the small subunit of the adaptor protein 1 complex (AP-1), which plays roles in clathrin coat-assembly and trafficking between trans-Golgi network, endosomes and the plasma membrane. An AP1S1 knock-out (KO) of a CaCo2 intestinal cell line was generated to characterize intestinal AP1S1 deficiency as well as identified mutations by stable expression in KO background. Morphology and prototype transporter protein distribution were comparable between parental and KO cells. We observed altered localization of tight-junction proteins ZO-1 and claudin 3, decreased transepithelial electrical resistance and an increased dextran permeability of the CaCo2-AP1S1-KO monolayer. In addition, lumen formation in 3D cultures of these cells was abnormal. Re-expression of wild-type AP1S1 in CaCo2-AP1S1-KO cells reverted these abnormalities, while expression of AP1S1 containing either missense mutation did not. Our data indicate that loss of AP1S1 function causes an intestinal epithelial barrier defect, and that AP1S1 mutations can cause a non-syndromic form of congenital diarrhea, whereas 2 reported truncating AP1S1 mutations caused MEDNIK syndrome, characterized by mental retardation, enteropathy, deafness, neuropathy, ichthyosis, and keratodermia.