Delineation of LZTR1 mutation-positive patients with Noonan syndrome and identification of LZTR1 binding to RAF1-PPP1CB complexes
Delineation of LZTR1 mutation-positive patients with Noonan syndrome and identification of LZTR1 binding to RAF1-PPP1CB complexes
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DOI：
10.1007/s00439-018-1951-7
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发表时间：
2019-01-01
期刊：
影响因子：
5.3
通讯作者：
Aoki, Yoko
中科院分区：
文献类型：
--
作者：
Umeki, Ikumi;Niihori, Tetsuya;Aoki, Yoko
Rasopathies是一组由调节RAS/MAPK通路的基因突变引起的发育障碍，包括Noonan综合征(NS)、Costello综合征、心面皮肤综合征和其他相关疾病。最近的全外显子测序研究发现，LZTR1、PPP1CB和MRAS是Rasopathies中新的致病基因。然而，关于LZTR1突变阳性患者的表型和突变的功能特性的信息有限。为了确定LZTR1、PPP1CB和MRAS的变异，我们进行了有针对性的下一代测序，并重新检查了166名疑似Rasopathy患者的外显子组数据。我们在7名疑似NS的先证者中发现了8个LZTR1变异，包括一个从头变异，在一名NS患者中发现了一个已知的从头PPP1CB变异。其中一个先证者有两个复合杂合子LZTR1变异，提示常染色体隐性遗传。所有携带LZTR1变异的先证者都有心脏缺陷，包括肥厚型心肌病和房间隔缺损。七名先证者中有五人身材矮小或智力残疾。内源性LZTR1的免疫沉淀和Western blotting表明LZTR1与RAF1-PPP1CB结合。转染针对LZTR1的小干扰RNA的细胞显示，在Ser259处，RAF1的磷酸化水平降低。这些结果首次证明LZTR1与RAF1-PPP1CB复合体作为RAS/MAPK途径的一个组成部分。
RASopathies are a group of developmental disorders caused by mutations in genes that regulate the RAS/MAPK pathway and include Noonan syndrome (NS), Costello syndrome, cardiofaciocutaneous syndrome and other related disorders. Whole exome sequencing studies recently identified LZTR1, PPP1CB and MRAS as new causative genes in RASopathies. However, information on the phenotypes of LZTR1 mutation-positive patients and functional properties of the mutations are limited. To identify variants of LZTR1, PPP1CB, and MRAS, we performed a targeted next-generation sequencing and reexamined previously analyzed exome data in 166 patients with suspected RASopathies. We identified eight LZTR1 variants, including a de novo variant, in seven probands who were suspicious for NS and one known de novo PPP1CB variant in a patient with NS. One of the seven probands had two compound heterozygous LZTR1 variants, suggesting autosomal recessive inheritance. All probands with LZTR1 variants had cardiac defects, including hypertrophic cardiomyopathy and atrial septal defect. Five of the seven probands had short stature or intellectual disabilities. Immunoprecipitation of endogenous LZTR1 followed by western blotting showed that LZTR1 bound to the RAF1-PPP1CB complex. Cells transfected with a small interfering RNA against LZTR1 exhibited decreased levels of RAF1 phosphorylated at Ser259. These are the first results to demonstrate LZTR1 in association with the RAF1-PPP1CB complex as a component of the RAS/MAPK pathway.