Expression of the adhesion molecule spermatogenic immunoglobulin superfamily (SgIGSF) in mouse tissues

Spermatogenic immunoglobulin superfamily (SgIGSF) is an adhesion molecule originally isolated from adult mouse testis. In the testis, SgIGSF is expressed specifically in spermatogenic cells and may be involved in spermatogenesis. SgIGSF may also be involved in synapse formation and tumor suppression. In the present study, we examined the expression and cellular localization of SgIGSF in the entire adult mouse organs and tissues using Western blot analysis and immunohistochemistry at light and electron microscopic levels. Western blot analysis revealed that SgIGSF is expressed not only in the testis but also in the liver, lung, and nervous system including the cerebrum, cerebellum and sciatic nerve. The nervous system as well as testis showed multiple immunoreactive bands ranging from 45 to 100 kDa, whereas the liver and lung showed a single 100 kDa band. Immunohistochemisfry demonstrated that in the nervous system, SgIGSF is localized to the membranes of synapses, axons and Schwann cells. In contrast, in the lung and liver SgIGSF was localized to the membranes of apposing respiratory epithelial cells, hepatocytes and biliary epithelial cells. These results suggested that SgIGSF plays multiple physiological roles in the adult mouse as an adhesion molecule.