MAGE-B4, a binding partner of PRAMEF12, is dispensable for spermatogenesis and male fertility in mice

Melanoma antigen (MAGE)-B4 belongs to the MAGE-B family genes, which are located on the X chromosome. The MAGE-B family genes are classified as cancer-testis antigens, as they are primarily expressed in the testis and are aberrantly expressed in most cancers. Although a no-stop mutation in MAGE-B4 causes rare X-linked azoospermia and oligozoospermia phenotype in humans, the specific function of MAGE-B4 on spermatogenesis in mice remains unclear. In this study, we identified MAGE-B4 as a binding partner of PRAME family member 12, which plays an important role in the maintenance of mouse spermatogenic lineage in juvenile testes. Additionally, we found that Mage-b4 transcripts were restricted to the testis and that Mage-b4 was specifically expressed in spermatogonia. To explore the function of MAGE-B4 in spermatogenesis, we generated a Mage-b4 knockout (KO) mouse model using CRISPR/Cas9 technology. However, we found that Mage-b4 KO males displayed normal testicular morphology and fertility. Further histological analysis revealed that all stages of spermatogenic cells were present in the seminiferous tubules of the Mage-b4 KO mice. Altogether, our data suggest that Mage-b4 is dispensable for mouse spermatogenesis and male fertility.