The Booroola mutation in sheep is associated with an alteration of the bone morphogenetic protein receptor-IB functionality.
The hyperprolificacy phenotype of Booroola ewes is due to the presence of the FecB(B) allele at the FecB locus, recently identified as a single amino acid substitution (Q249R) in the bone morphogenetic protein (BMP) type-IB receptor (BMPR1B), and is associated with a more precocious differentiation of ovarian granulosa cells (GCs). To evaluate the consequences of the Booroola mutation on BMPR1B functions, the action of ligands of the transforming growth factor-beta (TGFbeta)/BMP family that act through (growth and differentiation factor-5, BMP-4) or independently of (activin A, TGFbeta-1) BMPR1B were studied on primary cultures of GCs from homozygous FecB(+) and FecB(B) ewes. All the tested TGFbeta/BMP family ligands inhibited progesterone secretion by FecB(+) GCs. Those inhibitory effects were lower for GCs from preovulatory (5-7 mm diameter) than from small antral follicles (1-3 mm diameter). The presence of the Booroola mutation was associated with a 3- to 4-fold (P<0.001) decreased responsiveness of GCs from FecB(B) compared with FecB(+) small follicles to the action of BMPR1B ligands. In contrast, TGFbeta-1 and activin A had similar inhibitory effects on progesterone secretion by GCs from FecB(+) and FecB(B) small follicles. No difference between genotypes was observed with GCs from preovulatory follicles. In transfection experiments with HEK-293 cells, co-expression of FecB(+) BMPR1B and BMPR2 resulted in a 2.6-fold (P<0.01) induction of the activity of a BMP-specific luciferase reporter construct by BMP-4. Interestingly, no response to BMP-4 was observed when cells were transfected with the FecB(B) form of the BMPR1B receptor. Overall, these data strongly suggest that the Q249R mutation is associated with a specific alteration of BMPR1B signaling in hyperprolific Booroola ewes.
Fabre
S
S
INRA, Physiologie de la Reproduction et des Comportements, UMR 6073 INRA-CNRS-Université François Rabelais, 37380 Nouzilly, France.
Pierre
A
A
Pisselet
C
C
Mulsant
P
P
Lecerf
F
F
Pohl
J
J
Monget
P
P
Monniaux
D
D
D028341:Activins / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D055415:Bone Morphogenetic Protein 4; D052005:Bone Morphogenetic Protein Receptors, Type I; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D005838:Genotype; D006107:Granulosa Cells / Q000378:metabolism*; D055428:Growth Differentiation Factor 5; D006801:Humans; D028322:Inhibin-beta Subunits / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D012756:Sheep / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology
C525809:BMP4 protein, human; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; C525893:GDF5 protein, human; D055428:Growth Differentiation Factor 5; D017978:Receptors, Growth Factor; D016212:Transforming Growth Factor beta; C422405:activin A; D028341:Activins; D011374:Progesterone; D028322:Inhibin-beta Subunits; D017346:Protein Serine-Threonine Kinases; C498214:BMPR1B protein, human; D052005:Bone Morphogenetic Protein Receptors, Type I