The Adisintegrin and metalloprotease domain-containing (ADAM) family of proteins is involved in cell adhesion, migration, proteolysis, and signaling. Many ADAMs are required for reproduction; however, the role of Adam6 has remained largely unknown. In the course of humanizing the mouse immunoglobulin heavy chain (IgH) locus, we generated Adam6-deficient mice that demonstrate severe subfertility. We decided to elucidate the role of ADAM6 in fertility and explore the underlying mechanisms. Despite normal sperm development and motility, Adam6-deficient mice display diminished male fertility, have abnormal sperm adhesion, and most importantly cannot transition from uterus to oviduct. To test whether ADAM6 is required for sperm's binding to extracellular matrix (ECM) components, we used a panel of ECM components and showed that unlike normal sperm, Adam6-deficient sperm cannot bind fibronectin, laminin, and tenascin. Reintroduction of Adam6 into these deficient mice repaired sperm interaction with ECM, restored male fertility, and corrected the sperm transport deficit. Together, our data suggest that ADAM6, either alone or in complex with other proteins, aids sperm transport through the female reproductive tract by providing a temporary site of attachment of sperm to ECM components prior to ascent into the oviduct.

Summary Sentence

ADAM6, a testis-specific protein, is required for sperm ascent into the oviduct and its deletion results in deficits in both sperm–sperm and sperm–extracellular matrix associations.