RESUMEN
Biallelic loss-of-function mutation of NUP210L, encoding a testis-specific nucleoporin, has been reported in an infertile man whose spermatozoa show uncondensed heads and histone retention. Mice with a homozygous transgene intronic insertion in Nup210l were infertile but spermatozoa had condensed heads. Expression from this insertion allele is undefined, however, and residual NUP210L production could underlie the milder phenotype. To resolve this issue, we have created Nup210lem1Mjmm , a null allele of Nup210l, in the mouse. Nup210lem1Mjmm homozygotes show uniform mild anomalies of sperm head morphology and decreased motility, but nuclear compaction and histone removal appear unaffected. Thus, our mouse model does not support that NUP210L loss alone blocks spermatid nuclear compaction. Re-analyzing the patient's exome data, we identified a rare, potentially pathogenic, heterozygous variant in nucleoporin gene NUP153 (p.Pro485Leu), and showed that, in mouse and human, NUP210L and NUP153 colocalize at the caudal nuclear pole in elongating spermatids and spermatozoa. Unexpectedly, in round spermatids, NUP210L and NUP153 localisation differs between mouse (nucleoplasm) and human (nuclear periphery). Our data suggest two explanations for the increased phenotypic severity associated with NUP210L loss in human compared to mouse: a genetic variant in human NUP153 (p.Pro485Leu), and inter-species divergence in nuclear pore function in round spermatids.