Characterization of the signalings and ovarian function of bone morphogenetic protein 8a and 8b
| Autor: | Fang-Ju Wu, 吳芳儒 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Bone morphogenetic proteins (BMPs) have been known to be indispensable for reproduction system. A previous study indicates that targeted depletion of either Bmp8a or Bmp8b causes male infertility due to the degeneration of primordial germ cells and epididymal epithelia, indicative of their importance in the maintenance of spermatogenesis and epididymal function. However, no direct signaling pathway of BMP8 in cells has been clarified in vitro due to the lack of functional BMP8 proteins. In addition, our preliminary data have shown that Bmp8a and Bmp8b transcripts are abundant not only in rat testis, but also in rat ovary. Therefore, we wanted to uncover the BMP8A and BMP8B downstream signaling and discover their importance in the ovary. Firstly, we generated different constructs for producing the recombinant BMP8 proteins and confirming their BMP activities. Surprisingly, we found that bioactive BMP8 recombinant protein not only mediates the BMP signaling, but also the TGFβ/activin signaling in the reporter assay. Immunoblotting against phospho-Smad1/5/8 and phospho-Smad2 confirmed that BMP8 is capable of activating both pathways. The reporter assay with either ALK3, 4, 5 or 6 overexpression individually enhances the reporter signal, indicating they are the signaling receptors of BMP8. Using a rat superovulation model and ovarian microdissection, we found the expressions of Bmp8a and Bmp8b are upregulated by luteinizing hormone within six hours. The expressions are mainly located in cumulus cell-oocyte complex (COC). Furthermore, we found that mBMP8A induced COC, which were isolated from preovulatory follicles, to start cumulus cell expansion. Thus, these results suggest that BMP8 mediates signals to activate both the BMP and TGFβ/activin signaling through Smad1/5/8 and Smad2 complex, respectively. In the future, the other roles of BMP8 in addition to induction of cumulus cell expansion need more investigation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|