A de novo C-terminal truncation mutation in NUP205 as a key factor in premature ovarian insufficiency

STUDY QUESTION: Does nucleoporin 205 (NUP205) deficiency caused by a novel de novo truncation mutation underlie the pathogenesis of premature ovarian insufficiency (POI)? SUMMARY ANSWER: NUP205 plays a critical role in ovarian development, and mutations in NUP205 represent a key factor in the pathogenesis of POI. WHAT IS KNOWN ALREADY: POI is a highly heterogeneous disorder with a significant genetic basis. The nuclear pore complex (NPC) is a fundamental channel mediating nucleocytoplasmic transport, with NUP205 serving as a key scaffold component of the NPC. STUDY DESIGN, SIZE, DURATION: This study employed a multilevel genetic and functional investigation, starting with whole-exome sequencing (WES) of a POI pedigree. Clinical significance was further assessed through a large-scale cohort involving 1030 POI cases. Functional validation was performed using the in vitro human cell line COV434 and an in vivo zebrafish model. PARTICIPANTS/MATERIALS, SETTING, METHODS: A Chinese family with idiopathic POI was recruited. To evaluate the clinical prevalence of NUP205 variants, WES data from a previously published cohort of 1030 POI cases were rescreened. Candidate variants were prioritized based on American College of Medical Genetics and Genomics guidelines and the functional impact of the identified mutation was further evaluated through protein structural modeling. The expression of NUP205 in follicles was determined by reanalyzing public ovarian single-cell RNA sequencing datasets and confirmed via immunofluorescence on human ovarian tissues. Functional assays were performed through siRNA-mediated knockdown in COV434 cells, complementing phenotypic and ultrastructural analyses of a CRISPR/Cas9-generated nup205 (p.R1057*) truncation zebrafish model. MAIN RESULTS AND THE ROLE OF CHANCE: A novel heterozygous nonsense mutation in NUP205 c.3160C>T (p.R1054*) was identified in the index pedigree, which was absent in public genomic databases. Expanded screening of the cohort identified five additional families carrying NUP205 variants (three heterozygous and two compound heterozygous) affecting highly conserved residues. In vitro, NUP205 knockdown in COV434 cells impaired the protein stability of NUP93 and NUP62, ultimately leading to NPC structural defects. In vivo, a zebrafish model carrying the equivalent nup205 (p.R1057*) mutation exhibited impaired oogenesis, compromised fertility, and lower fertilization rates. Transmission electron microscopy revealed abnormal NPC morphology in the theca cells of the mutant follicles. These findings demonstrate that NUP205 is essential for ovarian development and suggest that its deficiency is a key factor in POI pathogenesis, indicating that the observed association is unlikely to be due to chance. LIMITATIONS, REASONS FOR CAUTION: Although we identified additional NUP205 variants in a large POI cohort, the detailed molecular mechanisms of these specific variants remain to be further investigated. WIDER IMPLICATIONS OF THE FINDINGS: These findings identify NUP205 as a novel genetic contributor to POI, expanding the spectrum of nucleoporin-related reproductive disorders. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Natural Science Foundation of China (U24A20659 and 82500964). The authors declare that they have no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.