Gdf9 and bmp15

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GDF9 and BMP 15 are secreted by oocyte and these regulates the function of cumulus cells thus helps in enhancing the oocyte developmental competence and embryo development.

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Gdf9 and bmp15

  1. 1. Muzamil Ahmad M.V.Sc. Student Animal Biotechnology
  2. 2.  Recent reproductive technologies have opened up possibilities in accelerating genetic gain and enhancing production potential in livestock .
  3. 3.  These        technologies include Artificial insemination (AI). Multiple ovulation and embryo transfer (MOET). In vitro production of embryos. Animal Cloning. Estrus synchronization. Marker assisted selection ,and Transfer of genes between animals. (transgenesis).
  4. 4.  In vitro production of embryos (IVEP)has emerged as a reliable alternative method to conventional ovarian super stimulation methods  Important research tool for animal embryology.
  5. 5.  Previous studies have clearly demonstrated that, while the intrinsic quality of the oocyte determines the proportion of oocytes developing to blastocysts.  The post-fertilization culture environment has the biggest influence on blastocyst quality. [Russell et al., 2006]  However, the exact influence of culture conditions during critical events is still unknown.
  6. 6. Animal cloning Transgenic animal production IVM In vitro embryo production IVF
  7. 7.  Oocyte in vitro maturation (IVM) is a reproductive technology that enables mature oocytes to be generated ex vivo.  IVM involves removal of cumulus-oocyte-complexs (COCs) and culturing them into standard culturing medium for 24h upto meiosis II.
  8. 8.  The efficiency of IVM technologies or assisted reproductive technologies (ARTs) is limited by   The oocyte developmental competence ,and Subsequent embryo development as compared to in vivo.
  9. 9. a) Meiotic Maturation b) Fertilization c) Preimplantation development d) Development to term /successful pregnancy
  10. 10.  Oocytes gradually and sequentially acquire developmental competence during the course of folliculogenesis as the oocyte grows and its companion somatic cells differentiate. (Eppig et al., 1994).
  11. 11. (1) The origin of the oocyte. (2) Follicle health. (3) Hormonal stimulation. (Lonergan et al., 1994) (Blondin et al.,1995) (Sirard et al., 2006) (4) Communication between the oocyte and its surrounding cumulus cells (CCs) (Krisher, 2004)
  12. 12.  Previously it was thought that oocyte is a passive recipient of Cumulus Cell function.  But now it is evidenced oocyte is a key regulator of its developmental competence by regulating its micro environment via the secretion of paracrine molecules like GDF9 , BMP15 etc.
  13. 13.  Oocyte plays active role throughout folliculogenesis via secretion of paracrine factors ( like GDF9 & BMP15) that maintain an appropriate microenvironment for the acquisition of its developmental competence. (Dong et al., 1996; Eppig et al., 1997;Gilchrist et al., 2004).
  14. 14.  Falck and colleagues demonstrated in 1959 that intact rabbit preovulatory follicles do not luteinize when transplanted into the anterior chamber of the eye.  In contrast to oocyte-free explants of either the follicle wall or granulosa cells that do undergo morphological luteinization. (Falck 1959).
  15. 15.  Subsequently, Nalbandov and colleagues confirmed this work using rabbit dominant follicles in situ, showing that removal of the oocyte caused spontaneous luteinization of granulosa and theca cells and elevated secretion of progesterone to levels produced by corpora lutea. ( Nalbandov 1970).
  16. 16.  It is known that bidirectional interactions occurs between oocyte and cumulus cells.  Bidirectional interaction occurs via; gap junction and paracrine signaling.  Helps in growth and development of both oocyte and cumulus cells. ( Eppig et al.,1997,2002;Matzuk et al., 2002)
  17. 17.  Growth differentiation factor 9 (GDF9)and Bone morphogenetic protein 15 (BMP15) are two closely related members of the Transforming Growth Factorβ (TGF-β ) superfamily.  TGF-β superfamily ; large family of structurally related proteins.  Controls proliferation, differentiation, development etc in variety of cells/tissues.
  18. 18.  GDF9 & BMP15 are expressed and translated in oocytes .  Synthesized as preproproteins, consisting of a signal peptide, a large proregion and a mature region. ( Shimasaki et al., 2004)
  19. 19. Properties :  Lack of 4th cysteine residue (otherwise conserved in other members of TGF-β superfamily)   Function mostly as homodimer/and or sometimes as heteriodimers.  Required for female fertility: as mutations (homozygus) leads to infertility due to block in follicullogenisis at early stage.
  20. 20.  GDF9 and BMP 15 have recently been shown to signal through known TGF-β superfamily receptors to activate the SMAD intracellular cascade
  21. 21.  Two pathways BMP pathway and TGFβ/activin pathway which respectively activate SMAD1/5/8 and SMAD2/3 messengers  BMP15 utilizes BMP pathway to activate SMAD1/5/8  GDF9 utilizes SMAD2/3
  22. 22. Proliferation of Granulosa cells Differentiation of Granulosa cells Prevention of apoptosis Inhibition of Luteinization Cumulus cell expansion Metabolism
  23. 23. GDF 9 and BMP15 stimulates granulosa cell proliferation and DNA synthesis. Expression of Ccnd2 mRNA cell cycle transcript >>>>>cyclin d 2 protein of cell cycle  Assessed by uptake of [H3]thymidine  (Glichrist et al.,2006)
  24. 24. Oocyte secreted factors i-e,GDF9 & BMP15 differentiates the granulosa cells into mural cells (MGCs) and cumulus cells (CCs) at antral stage of follicle.  MGCs under influence of FSH  CCs under influence of OSFs  (Hussein et.al.,2005;Diaz et al.,2007)
  25. 25.  BMP15 prevent Cumulus Cell apoptosis by maintaining a localized gradient of antiapoptotic factors within the COC (Hussein et al., 2005)   Expression of anti-apoptotic gene Bcl2 Suppression of pro-apoptotic protein Bax
  26. 26.  Suppression of LH receptor (LHCGR) ( Eppig et al.,1997)  Inhibition of FSH induced progestrone production
  27. 27.  Two signaling pathways:(i) Gonadotrophin or epidermal growth factor (EGF) stimulation and (ii) Paracrine signals of oocyte (GDF9 &BMP15)  Synthesise extracellular matrix (ECM)  Hyaluronan (HA) major component  tumor necrosis factor alpha induced protein 6 (TNFAIP6)  Pentraxin 3(PTX3) (Russell et al., 2006)
  28. 28.  Prior to the LH surge, cumulus cells require GDF-9 to support the metabolic cascades such as glycolysis and sterol biosynthesis (Sugiura et al. 2005).  Evidence for this comes from findings of reduced cholesterol synthesis from acetate in cumulus-oocyte complexes of Gdf9 − /−mutant mice. (Sugiura et al. 2005).
  29. 29. IVF IVF Blastocyst Inner cell mass Blastocyst ICM Hussein et al.,2005..
  30. 30. Treatment No.of oocytes used % Cleavage Rate % Blastocycst from cleaved oocytes CONTROL 205 86.5 ±3.2 41.0 ±0.9 GDF9 191 88.1 ±2.0 49.5 ±3.9 BMP15 189 88.7 ±4.2 57.5 ±2.4 GDF9+BMP15 184 88.9 ±2.9 55.1 ±4.5 293H 187 80.4 ±2.2 27.1 ±3.1 (Hussein et al.,2005)
  31. 31.  It is now clear that oocyte regulates the cumulus cell functions like differentiation, apoptosis, expansion, luteinization  And cumulus cells provide microenvironment to oocytes for development  In order to increase the efficiency of ARTs the OSFs (GDF9 & BMP15) may be utilized in culture media

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