Expression and Cyclic Change of Betaglycan in the Rat Oviduct

Abstract

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. Key words: Betaglycan, Estrous cycle, Oviduct, Rat, Transforming growth factor (TGF)-β (J. Reprod. Dev. 55: [200][201][202][203][204][205] 2009) etaglycan is a member-anchored proteoglycan originally characterized as a type III receptor for transforming growth factor-β1 (TGFβ), the prototype of a superfamily of growth factors involved in regulation of cell proliferation, differentiation and development. Betaglycan binds TGFβ isoforms with high affinity and increases the functional interaction between TGFβ and its type I and type II signaling receptors [1,2]. Rat betaglycan encodes a 91.6-kDa protein core that is further modified by N-linked glycosyl residues and by heparin and chondroitin sulfate side chains. The betaglycan protein consists of a large extracellular domain, a single transmembrane domain, and a short intracellular domain [3,4]. Although the short 43-amino acid cytoplasmic domain lacks an obvious signaling motif, it is enriched by serines and threonines [3,4]. Recently it has been demonstrated that betaglycan can bind inhibin A with high affinity and interfere with activin A to bind to its type II receptor [5]. It has been reported that betaglycan is expressed in the adrenal gland, ovary, uterus and pituitary, which have essential reproductive functions [6][7][8][9], whereas TGFβ are expressed in the ovary, testis, pre-a...

Mating decreases plasma levels of TGFβ1 and regulates myosalpinx expression of TGFβ1/TGFBR3 in the rat

“…Expression of TGFβ‐superfamily ligands and their receptors has been reported in the oviduct of a variety of species (Dalton et al, ; Zhao et al, ; Chow et al, ; Kubota et al, ; Jiwakanon et al, ), and is often dependent on the oestrous cycle and pregnancy, suggesting that ovarian steroids contribute to their regulation (Zhao et al, ). We found that Tgfb1 level decreased in the myosalpinx at 1 and 3 hr post‐mating while abundance of TGFBR3 protein increased 3 hr earlier in the myosalpinx of mated versus unmated rats, although this did not correlate with Tgfbr3 transcript levels.…”

“…Upon deposition of semen, seminal TGFb1 modulates the immune response by interacting with epithelial cells of the female reproductive tract (Robertson et al, 2002). Expression of TGFb1 and its receptors have been reported in rat, mouse, and human oviducts; in all cases, the TGFb1 secreted into the oviduct and uterine fluid influences the sperm, oocyte, spermÀoocyte interactions, and early-embryo development (Zhao et al, 1994;Chow et al, 2001;Jones et al, 2006;Kubota et al, 2009;Omwandho et al, 2010).…”