Laminins are important for basement membrane structure and function. The
laminin alpha2 chain is a major component of muscle basement membranes, and mutations in the
laminin alpha2 gene lead to congenital
muscular dystrophy in humans and mice. Although the
laminin alpha2 chain is prominently expressed in testicular basement membranes, its role in testis has remained unclear. Here, we show that
laminin alpha1, alpha2, beta1, beta2, gamma 1, and gamma 3 chains are the major
laminin chains in basement membranes of seminiferous tubules. In
laminin alpha2 chain-deficient dy(3 K)/dy(3 ASK) mice, lack of
laminin alpha2 chain led to concurrent reduction of
laminin gamma 3 chain and abnormal testicular basement membranes. Seminiferous tubules of
laminin alpha2 chain-deficient dy(3 K)/dy(3 K) mice displayed a defect in the timing of lumen formation, resulting in production of fewer spermatides. We also demonstrate that overexpression of
laminin alpha1 chain in testis of dy(3 K)/dy(3 K) mice compensated for
laminin alpha2 chain deficiency and significantly reversed the appearance of the histopathological features. We thus provide genetic data that
laminin alpha chains are essential for normal testicular function in vivo.