Xu Yang, Gao Jie, An Yang, Zou Chenxi, Ding Guoqing, Yang Guohua
Department of Respiratory and Critical Care Medicine, The Eighth Medical Center, Chinese PLA General Hospital, Beijing, China.
Department of Pathology, The First Medical Center, Chinese PLA General Hospital, Beijing, China.
Hum Mutat. 2025 Feb 3;2025:7194418. doi: 10.1155/humu/7194418. eCollection 2025.
Birt-Hogg-Dubé syndrome (BHD) was an autosomal dominant disorder caused by a mutation in the folliculin () gene and characterized by benign cutaneous fibrofolliculomas in the head and neck, pulmonary cysts, spontaneous pneumothorax, and combined renal tumors. This study reported a familial case presenting multiple pulmonary bullae, recurrent spontaneous pneumothorax, diffuse cystic lesions in both lungs, and renal cysts. To further clarify the diagnosis, next-generation sequencing (NGS) was performed in conjunction with the clinical diagnostic criteria for Birt-Hogg-Dubé. The eukaryotic recombinant expression vectors of pEGFP-C1- and knock-in mutation by CRISPR/Cas9 were conducted in 293 T and BEAS-2B cell lines. The mRNA and protein expression of the mutation were verified by fluorescence quantitative PCR and Western blot assay. Nonsense-mediated mRNA decay (NMD) assays and immunohistochemical assays were conducted to elucidate the pathogenicity of the mutation and explore potential mechanisms. A unique, novel, unspecified significance mutation NM_144997.7: c.21_22del (p. Cys8 Profs28) in Exon 4 was detected in both patients. The results demonstrated that the newly identified frameshift mutation significantly decreased mRNA and protein expression. The NMD complex recognized and degraded mRNAs containing a premature termination codon (PTC) in the open reading frame of the frameshift mutation, resulting in haploinsufficiency and ultimately contributing to the manifestation of BHD. Protein expression on the AMP-activated protein kinase (AMPK), Wnt/-catenin, and mammalian target of rapamycin (mTOR) signaling pathways by immunohistochemistry indicated that frameshift mutations were responsible for BHD through the activation of AMPK, Wnt/-catenin, and mTOR signaling pathways. The study demonstrated that a novel frameshift mutation was responsible for the pathogenesis of BHD and preliminarily demonstrated that causes BHD through the AMPK, Wnt/-catenin, and mTOR signaling pathways.
Birt-Hogg-Dubé综合征（BHD）是一种常染色体显性疾病，由卵泡抑素（FLCN）基因突变引起，其特征为头颈部出现良性皮肤纤维毛囊瘤、肺囊肿、自发性气胸以及合并肾肿瘤。本研究报告了1例家族性病例，该病例表现为多发肺大疱、复发性自发性气胸、双肺弥漫性囊性病变以及肾囊肿。为进一步明确诊断，结合Birt-Hogg-Dubé的临床诊断标准进行了二代测序（NGS）。在293 T和BEAS-2B细胞系中构建了pEGFP-C1-FLCN真核重组表达载体并通过CRISPR/Cas9进行FLCN敲入突变。通过荧光定量PCR和蛋白质免疫印迹法验证FLCN突变的mRNA和蛋白质表达。进行了无义介导的mRNA降解（NMD）检测和免疫组织化学检测以阐明该突变的致病性并探索潜在机制。在两名患者中均检测到外显子4中一个独特的、新的、意义未明的突变NM_144997.7：c.21_22del（p.Cys8Profs28）。结果表明，新鉴定的FLCN移码突变显著降低了FLCN mRNA和蛋白质表达。NMD复合物识别并降解了FLCN移码突变开放阅读框中含有提前终止密码子（PTC）的mRNA，导致单倍体不足并最终促使BHD的表现。通过免疫组织化学对AMP活化蛋白激酶（AMPK）、Wnt/β-连环蛋白和雷帕霉素靶蛋白（mTOR）信号通路进行蛋白质表达分析表明，FLCN移码突变通过激活AMPK、Wnt/β-连环蛋白和mTOR信号通路导致BHD。该研究表明，一种新的FLCN移码突变是BHD发病机制的原因，并初步证明FLCN通过AMPK、Wnt/β-连环蛋白和mTOR信号通路导致BHD。
