Abstract
Although the fallopian tube provides a sufficient environment for fertilization and early embryo development, the mechanism by which it does this is unclear. It is known that the transforming growth factorβ (TGFβ) superfamily plays important roles in various reproductive functions. Betaglycan, originally characterized as a TGFβ type III receptor lacking a clearly identifiable signaling motif, has been shown to be important for the high-affinity binding of TGFβs to the type II receptor. To our knowledge, there has been no study showing expression of betaglycan in the rat oviduct. Therefore, in this study, we examined the distribution of betaglycan in various rat tissues and its expression patterns in the oviduct during the estrous cycle. Northern blot analysis of various rat tissues showed that the adrenal gland, ovary and oviduct contained abundant amounts of 6.4-kb betaglycan mRNA. Furthermore, the mRNA level of betaglycan was highest after the LH surge that induced ovulation. The betaglycan protein, detected using immunohistochemistry, was especially abundant in the epithelium of the oviduct. Furthermore, in pregnant mare serum gonadotropin (PMSG) primed-rats, the expression of betaglycan was increased significantly by stimulation with human chorionic gonadotropin (hCG). RT-PCR analysis showed co-localization of other TGFβ family receptors (TGFβ types I and II, activin receptor types Ia and Ib and activin receptor types IIa and IIb) with betaglycan in the oviduct. Since betaglycan along with other TGFβ family receptors is abundantly expressed in the epithelium of the oviduct and its expression changes during estrous, it may also play an important role in the oviduct.
