A dominant negative variant of RAB5B disrupts maturation of surfactant protein B and surfactant protein C.
A dominant negative variant of RAB5B disrupts maturation of surfactant protein B and surfactant protein C.
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DOI：
10.1073/pnas.2105228119
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发表时间：
2022-02-08
影响因子：
11.1
通讯作者：
Schedl T
中科院分区：
文献类型：
--
作者：
Huang H;Pan J;Spielberg DR;Hanchard NA;Scott DA;Burrage LC;Dai H;Murdock D;Rosenfeld JA;Mohammad A;Huang T;Lindsey AG;Kim H;Chen J;Ramu A;Morrison SA;Dawson ZD;Hu AZ;Tycksen E;Silverman GA;Baldridge D;Wambach JA;Undiagnosed Diseases Network;Pak SC;Brody SL;Schedl T
Rab5 GTPase在内吞途径的早期内小体融合中起作用。在此，我们认为RAB5B在肺中产生成熟的表面活性蛋白SP-B和SP-C的调节分泌途径中也具有非典型的囊泡融合功能。这一功能是通过对一名患有间质性肺疾病的先证者的调查发现的，该先证者提示存在表面活性物质功能障碍，他携带RAB5B基因的从头Asp136His变体。我们在线虫中的建模提供了关于遗传和细胞生物学机制的信息，对先证者和正常肺活检的分析表明，RAB5B和EES在表面活性蛋白的加工/运输中具有功能。这项工作表明RAB5B p.Asp136His导致了表面活性物质功能障碍。表面活性物质蛋白SP-B和SP-C的致病变异可导致表面活性物质缺乏和间质性肺疾病。表面活性蛋白是作为前体(PROSP-B、PROSP-C)合成的，通过囊泡调节的分泌途径进行运输和加工；然而，对囊泡运输事件的控制还不完全清楚。通过未诊断疾病网络，我们评估了一名提示肺表面活性物质缺乏的间质性肺疾病儿童。已知的表面活性物质功能障碍基因的变异在三个外显子组测序中没有发现。相反，在RAS/Rab GTP酶家族的核苷酸结合区p.Asp136His中发现了RAB5B的一个新杂合型变异体。通过将先证者变体敲入直系同源基因Rab-5的保守位置(Asp135)，对秀丽隐杆线虫进行了功能研究。遗传分析表明，Rab-5[Asp135His]具有破坏性，产生强烈的显性负性基因产物。RAB-5[Asp135His]杂合子在内吞作用和内小体早期融合方面也存在缺陷。先证者肺活检免疫染色结果显示，肺泡II型细胞RAB5B和EE标志物EEA1显著减少，成熟SP-B和SP-C显著减少，而ProSP-B和ProSP-C正常。此外，正常肺染色显示RAB5B和EEA1与ProSP-B和ProSP-C共存。这些结果表明，RAB5B、Asp136His和EE的显性负性作用导致在加工/运输过程中产生成熟的SP-B和SP-C的缺陷，从而导致间质性肺疾病，而RAB5B和EES在表面活性物质的分泌途径中正常发挥作用。综上所述，这些数据提示了RAB5B的非规范功能，并确认RAB5B p.Asp136His是表面活性物质功能障碍的遗传机制。
The Rab5 GTPase functions in early endosome (EE) fusion in the endocytic pathway. Here, we propose that RAB5B also has a noncanonical vesicular fusion function in the regulated secretion pathway that produces mature surfactant proteins SP-B and SP-C in the lung. This function was revealed from investigation of a proband with interstitial lung disease suggestive of a surfactant dysfunction disorder who carried a de novo Asp136His variant in the RAB5B gene. Our modeling in C. elegans provided information on the genetic and cell biological mechanism, and analyses of proband and normal lung biopsies suggested a function for RAB5B and EEs in surfactant protein processing/trafficking. This work indicates that RAB5B p.Asp136His causes a surfactant dysfunction disorder. Pathogenic variants in surfactant proteins SP-B and SP-C cause surfactant deficiency and interstitial lung disease. Surfactant proteins are synthesized as precursors (proSP-B, proSP-C), trafficked, and processed via a vesicular-regulated secretion pathway; however, control of vesicular trafficking events is not fully understood. Through the Undiagnosed Diseases Network, we evaluated a child with interstitial lung disease suggestive of surfactant deficiency. Variants in known surfactant dysfunction disorder genes were not found in trio exome sequencing. Instead, a de novo heterozygous variant in RAB5B was identified in the Ras/Rab GTPases family nucleotide binding domain, p.Asp136His. Functional studies were performed in Caenorhabditis elegans by knocking the proband variant into the conserved position (Asp135) of the ortholog, rab-5. Genetic analysis demonstrated that rab-5[Asp135His] is damaging, producing a strong dominant negative gene product. rab-5[Asp135His] heterozygotes were also defective in endocytosis and early endosome (EE) fusion. Immunostaining studies of the proband’s lung biopsy revealed that RAB5B and EE marker EEA1 were significantly reduced in alveolar type II cells and that mature SP-B and SP-C were significantly reduced, while proSP-B and proSP-C were normal. Furthermore, staining normal lung showed colocalization of RAB5B and EEA1 with proSP-B and proSP-C. These findings indicate that dominant negative–acting RAB5B Asp136His and EE dysfunction cause a defect in processing/trafficking to produce mature SP-B and SP-C, resulting in interstitial lung disease, and that RAB5B and EEs normally function in the surfactant secretion pathway. Together, the data suggest a noncanonical function for RAB5B and identify RAB5B p.Asp136His as a genetic mechanism for a surfactant dysfunction disorder.
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影响因子：
30.8
作者：
Kircher, Martin;Witten, Daniela M.;Jain, Preti;O'Roak, Brian J.;Cooper, Gregory M.;Shendure, Jay
通讯作者：
Shendure, Jay
DOI：
10.1165/rcmb.2003-0262oc
发表时间：
2004-04-01
影响因子：
6.4
作者：
Brasch, F;Johnen, G;Ochs, M
通讯作者：
Ochs, M
DOI：
10.1073/pnas.0707318105
发表时间：
2008-01-15
影响因子：
11.1
作者：
Dacks, Joel B.;Poon, Pak P.;Field, Mark C.
通讯作者：
Field, Mark C.
影响因子：
9.8
作者：
Heng, Jian;Lv, Peng;Liu, Feng
通讯作者：
Liu, Feng
影响因子：
64.8
作者：
Karczewski, Konrad J;Francioli, Laurent C;MacArthur, Daniel G
通讯作者：
MacArthur, Daniel G