Familial primary ovarian insufficiency associated with aSYCE1point mutation: Defective meiosis elucidated in humanized mice

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Objective</jats:title><jats:p>To investigate if nonsense mutation <jats:italic>SYCE1</jats:italic> c.613C˃T <jats:italic>-</jats:italic>found in women with familial primary ovarian insufficiency (POI)- is actually responsible for infertility, and to elucidate the involved molecular mechanisms.</jats:p></jats:sec><jats:sec><jats:title>Design</jats:title><jats:p>As most fundamental mammalian oogenesis events occur during the embryonic phase, thus hindering the study of POI’s etiology/pathogeny in infertile women, we have used CRISPR/Cas9 technology to generate a mouse model line with an equivalent genome alteration (humanized mice).</jats:p></jats:sec><jats:sec><jats:title>Setting</jats:title><jats:p>Academic research laboratories.</jats:p></jats:sec><jats:sec><jats:title>Interventions</jats:title><jats:p>We present the characterization of the biallelic mutant mice phenotype, compared to wild type and monoallelic littermates.</jats:p></jats:sec><jats:sec><jats:title>Animals</jats:title><jats:p>Studies were conducted employing the generated humanized mice. All studies were performed for both genders, except otherwise stated.</jats:p></jats:sec><jats:sec><jats:title>Main outcome measures</jats:title><jats:p>reproductive capability by fertility tests; gonadal histological analysis; evaluation of chromosome synapsis and synaptonemal complex (SC) assembly by immunolocalizations; protein studies by Western blotting; transcript quantification by RT-qPCR.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The studied mutation proved to be the actual cause of the infertile phenotype, both in female and male mice homozygous for the change, confirming infertility of genetic origin with a recessive mode of inheritance. The mechanisms that lead to infertility are related to chromosome synapsis defects; no putative truncated SYCE1 protein was observed, and <jats:italic>Syce1</jats:italic> transcript was hardly detected in biallelic mutants.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>We present for the first time the generation of humanized mice to study the actual consequences of a SC component mutation found in women with familial POI. By this approach we could confirm the suspected etiology, and shed light on the underlying molecular mechanism.</jats:p></jats:sec>