99: NXT2: a testis-specific RNA export hub essential for human spermatogenesis

Dicke A-K et al., Nature Communications - Proteomics, molecular and genetic analyses identify NXT2 as the predominant NXT protein in the human testis that binds NXF1, NXF2 and NXF3 and associates with nucleoporins. Loss-of-function variants in NXT2 are linked to azoospermia with Sertoli cell-only testes, while an NXF3 LoF causes severe sperm defects. Key terms: NXT2, NXF3, RNA export, azoospermia, spermatogenesis.

Study Highlights:
Proteomic pulldowns from adult human testis reveal NXT2 enrichment together with NXF1, testis-specific paralogs NXF2 and NXF3, and multiple nucleoporins, suggesting a testis-adapted mRNA export complex. Co-immunoprecipitation and deletion mapping show binding between NXT2 and NXF2/NXF3 is mediated by NTF2-like domains. Rare hemizygous loss-of-function variants or deletion of NXT2 were found in infertile men with non-obstructive azoospermia and predominant Sertoli cell-only histology, and an NXF3 stop-gain variant is associated with extreme oligoasthenoteratozoospermia. Functional assays in cells and tissue staining corroborate absent or truncated protein expression and link disrupted NXT2/NXF3 activity to impaired germ cell development and spermatogenesis.

Conclusion:
NXT2 is a testis-enriched core component of a human testis-adapted RNA nuclear export factor complex and loss of NXT2 function is strongly associated with disrupted germ cell development and male infertility.

Music:
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Article title:
NXT2 is a key component of the RNA nuclear export factor complex in the human testis and essential for spermatogenesis

First author:
Dicke A-K

Journal:
Nature Communications

DOI:
10.1038/s41467-025-61463-0

Reference:
Dicke A-K, Ahmedani A, Ma L, Herrmann L, van der Heijden GW, Koser SA, Krallmann C, Kalyon O, Xavier MJ, Veltman JA, Kliesch S, Neuhaus N, Kotaja N, Tüttelmann F & Stallmeyer B. NXT2 is a key component of the RNA nuclear export factor complex in the human testis and essential for spermatogenesis. Nature Communications. 2025;16:6254. doi:10.1038/s41467-025-61463-0

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-08-07.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the portions of the transcript that describe (1) the baseline RNA export pathway, (2) the NXT2-centered testis-specific export complex with NXF2/NXF3 and nucleoporins, (3) the genetic evidence from MERGE/Nijmegen cohorts linking NXT2 LoF to azoospermia and SCO, (4) the NXF3 LoF case and its phenotype, (5) LOEUF
- transcript topics: NXT2 as a testis-specific RNA export component; NXT2 interaction with NXF2 and NXF3 via NTF2-like domains; NXT2 predominance in adult human testis vs NXT1; Genetic evidence: NXT2 loss-of-function variants associated with azoospermia and Sertoli cell-only histology; NXF3 loss-of-function and extreme oligoasthenoteratozoospermia; Temporal expression: NXT2 in fetal germ cells; NXF3 in post-meiotic germ cells

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 6
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- NXT2 is a key component of the RNA nuclear export factor complex in the human testis
- NXT2 binds NXF2 and NXF3 via the NTF2-like domains; this interaction is domain-dependent
- NXT2 is the predominant NXT protein in the adult human testis; NXT1 is not part of the NXT2–NXF interaction network
- Loss-of-function variants in NXT2 are associated with azoospermia and Sertoli cell-only histology
- NXF3 loss-of-function variant linked to extreme oligoasthenoteratozoospermia
- LOEUF score for NXT2 indicates strong intolerance to loss-of-function variants

QC result: Pass.