Oocyte expression, secretion and somatic cell interaction of mouse bone morphogenetic protein 15 during the peri-ovulatory period

2015 ◽  
Vol 27 (5) ◽  
pp. 801 ◽  
Author(s):  
Brigitta Mester ◽  
Lesley J. Ritter ◽  
Janet L. Pitman ◽  
Adrian H. Bibby ◽  
Robert B. Gilchrist ◽  
...  

Bone morphogenetic protein 15 (BMP15) is a key intraovarian growth factor regulating mammalian fertility, yet expression and localisation of different BMP15 protein forms within ovarian follicles around the time of the preovulatory LH surge remains unclear. Using immunoblotting and immunocytochemistry, the present study identified that post-translationally processed BMP15 proregion and mature proteins are increasingly expressed and localised with cumulus and granulosa cells from mice treated with pregnant mare’s serum gonadotropin (PMSG) + human chorionic gonadotrophin (hCG). However, this increased expression was absent in cumulus–oocyte complexes matured in vitro. Pull-down assays further revealed that the recombinant BMP15 proregion is capable of specific interaction with isolated granulosa cells. To verify an oocyte, and not somatic cell, origin of Bmp15 mRNA and coregulated growth differentiation factor 9 (Gdf9), in situ hybridisation and quantitative polymerase chain reaction results confirmed the exclusive oocyte localisation of Bmp15 and Gdf9, regardless of treatment or assay method. Relative oocyte expression levels of Bmp15 and Gdf9 decreased significantly after PMSG + hCG treatment; nevertheless, throughout all treatments, the Bmp15 : Gdf9 mRNA expression ratio remained unchanged. Together, these data provide evidence that the preovulatory LH surge leads to upregulation of several forms of BMP15 protein secreted by the oocyte for putative sequestration and/or interaction with ovarian follicular somatic cells.

Endocrinology ◽  
2012 ◽  
Vol 153 (3) ◽  
pp. 1509-1518 ◽  
Author(s):  
Minna M. Pulkki ◽  
David G. Mottershead ◽  
Arja H. Pasternack ◽  
Pranuthi Muggalla ◽  
Helen Ludlow ◽  
...  

Genetic studies have identified bone morphogenetic protein-15 (BMP15) as an essential regulator of female fertility in humans and in sheep. Oocyte-derived BMP15 is a noncovalently linked dimeric growth factor mediating its effects to ovarian somatic cells in a paracrine manner. Although receptor ectodomains capable of binding BMP15 have previously been reported, no cell surface receptor complex involved in BMP15 signaling has previously been characterized. Here we have expressed and purified recombinant human BMP15 noncovalent and covalent dimer variants. The biological effects of these BMP15 variants were assessed in cultured human granulosa-luteal cells or COV434 granulosa cell tumor cells using BMP-responsive transcriptional reporter assays and an inhibin B ELISA. Biochemical characterization of ligand-receptor interactions was performed with affinity-labeling experiments using [125I]iodinated BMP15 variants. Both ligand variants were shown to form homodimers and to stimulate Smad1/5/8 signaling and inhibin B production in human granulosa cells in a similar manner. [125I]Iodination of both ligands was achieved, but only the covalent dimer variant retained receptor binding capacity. The [125I]BMP15S356C variant bound preferentially to endogenous BMP receptor 1B (BMPR1B) and BMPR2 receptors on COV434 cells. Binding experiments in COS cells with overexpression of these receptors confirmed that the [125I]BMP15S356C variant binds to BMPR1B and BMPR2 forming the BMP15 signaling complex. The results provide the first direct evidence in any species on the identification of specific cell surface receptors for a member of the GDF9/BMP15 subfamily of oocyte growth factors. The fact that BMP15 uses preferentially BMPR1B as its type I receptor suggests an important role for the BMPR1B receptor in human female fertility. The result is well in line with the demonstration of ovarian failure in a recently reported human subject with a homozygous BMPR1B loss-of-function mutant.


Reproduction ◽  
2005 ◽  
Vol 129 (4) ◽  
pp. 481-487 ◽  
Author(s):  
Kenneth P McNatty ◽  
Jennifer L Juengel ◽  
Karen L Reader ◽  
Stan Lun ◽  
Samu Myllymaa ◽  
...  

The oocyte-secreted polypeptide growth factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15, also known as GDF9B) have both been shown to be essential for ovarian follicular development and ovulation rate. In addition, it is known from both in vivo and in vitro studies that these factors co-operate in some manner. To date, most studies examining the in vitro effects of these growth factors have used the rodent model. However, the evidence suggests that these growth factors have somewhat different roles between rodents and ruminants. Therefore, the objectives of these studies were to examine the effects of GDF9 and BMP15, alone and together, on the functions of ovine and bovine granulosa cells under in vitro conditions. Ovine (o)BMP15 given together with murine (m)GDF9 or oGDF9 was more potent in stimulating 3H-thymidine incorporation by ovine granulosa cells compared with each growth factor alone. For bovine granulosa cells, there appeared to be little or no co-operativity between oBMP15 and oGDF9 as oBMP15 alone was as potent as any combination of the two growth factors in stimulating 3H-thymidine uptake. The species of origin of GDF9 affected the progesterone response in ovine granulosa cells with mGDF9 stimulating and oGDF9 inhibiting progesterone production. Ovine BMP15 alone had no effect on progesterone production by ovine granulosa cells and these growth factors did not appear to co-operate. FSH-stimulated progesterone production by bovine granulosa cells was most potently inhibited when oBMP15 and murine or ovine GDF9 were administered together. As was observed for progesterone, the species of origin of GDF9 affected inhibin production by ovine granulosa cells where mGDF9 inhibited while oGDF9 stimulated production. Murine GDF9 also inhibited inhibin production from bovine granulosa cells. For both ovine and bovine granulosa cells, BMP15 alone had no effect on inhibin production and there did not appear to be any co-operation between GDF9 and BMP15. These results indicate that the effects of BMP15 and GDF9 varied with respect to the species of origin of the growth factor. Moreover, the effects of GDF9 and BMP15 together were often co-operative and not always the same as those observed for these growth factors alone.


Reproduction ◽  
2005 ◽  
Vol 129 (4) ◽  
pp. 473-480 ◽  
Author(s):  
Kenneth P McNatty ◽  
Jennifer L Juengel ◽  
Karen L Reader ◽  
Stan Lun ◽  
Samu Myllymaa ◽  
...  

The oocyte-secreted polypeptide growth factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15, also known as GDF9B) have both been shown to be essential for ovarian follicular growth and function. The effects of murine (m) and ovine (o) GDF9 as well as oBMP15, alone or together, on 3H-thymidine uptake and progesterone and inhibin production by granulosa cells from rats were determined. Murine GDF9 stimulated thymidine incorporation by granulosa cells whereas oGDF9 and oBMP15 alone had no effect. However, oBMP15 given together with mGDF9 or oGDF9 was very potent in stimulating 3H-thymidine incorporation by granulosa cells with a greater than 3-fold stimulation compared with any growth factor alone. The synergistic effect of oBMP15 and oGDF9 was almost completely blocked by antibodies generated against these growth factors when administered either alone or in combination. While neither GDF9 (murine or ovine) nor oBMP15 were able to modulate FSH-stimulated progesterone production on their own, FSH-stimulated progesterone production by granulosa cells was potently inhibited when BMP15 and GDF9 were administered together. Immunoreactive α-inhibin levels increased more than 15-fold from granulosa cells when BMP15 and GDF9 were given together whereas consistent stimulatory effects of either growth factor alone were not observed. The effects of GDF9 and BMP15, when added together, were different than those observed for the growth factors alone. Therefore, we hypothesize that within the ovary, these oocyte-secreted growth factors co-operate to regulate proliferation and gonadotropin-induced differentiation of granulosa cells in mammals.


Reproduction ◽  
2011 ◽  
Vol 142 (4) ◽  
pp. 565-572 ◽  
Author(s):  
Jennifer L Juengel ◽  
Laurel D Quirke ◽  
Stan Lun ◽  
Derek A Heath ◽  
Peter D Johnstone ◽  
...  

Sheep with a heterozygous inactivating mutation in the bone morphogenetic protein 15 (BMP15) gene experience an increased ovulation rate during either a natural oestrous cycle or a cycle in which exogenous FSH and eCG (gonadotrophins) are given to induce multiple ovulations. The primary aim of these studies was to determine whether ewes immunised against BMP15 would also show an improved superovulation rate following exogenous gonadotrophin treatment. A secondary aim was to determine the effects of BMP15 immunisation on ovarian follicular characteristics. In most ewes (i.e. >75%) immunised with a BMP15-keyhole limpet haemocyanin peptide in an oil-based adjuvant in order to completely neutralise BMP15 bioactivity, there was no superovulation response to exogenous gonadotrophins. In ewes treated with exogenous gonadotrophins following a BMP15-BSA peptide immunisation in a water-based adjuvant to partially neutralise BMP15 bioactivity, the ovulation rate response was similar to the control superovulation treatment groups. Characterisation of follicular function revealed that the water-based BMP15-immunised animals had fewer non-atretic follicles 2.5–3.5 or >4.5 mm in diameter compared with controls. Basal concentrations of cAMP were higher in granulosa cells from animals immunised against BMP15 than control animals. There were no significant differences in the concentrations of cAMP between granulosa cells from BMP15- and control-immunised animals when given FSH or hCG, although there were differences in the proportions of follicles in different size classes that responded to FSH or hCG. Thus, immunisation against BMP15 may have been causing premature luteinisation and thereby limiting the numbers of follicles recruited for ovulation following treatment with exogenous gonadotrophins.


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