MicroRNA Profile of Granulosa Cells after Ovarian Stimulation Differs According to Maturity of Retrieved Oocytes

Abstract

Background: Recent animal studies demonstrated that regulating the microRNA (miRNA) in granulosa cells (GCs) modulates the meiotic competence of oocytes. However, the difference in expression profiles of miRNAs in human GCs according to the maturity of the oocyte still remains to be elucidated. Objective: This observational study investigated whether the miRNA profile of human GCs differs according to the maturity of the retrieved oocyte after controlled ovarian stimulation for in vitro fertilization (IVF). Methods: Ten women who underwent ovarian stimulation cycles with GnRH agonist long protocols were recruited. The follicular fluid (FF) from dominant follicles was individually aspirated at oocyte retrieval. Oocytes were divided into two groups according to oocyte maturity (“mature group” vs. “immature group”). GCs were collected from the FF and miRNA was analyzed using real-time PCR. Results: Mean number of MII oocytes in the mature group was 1.6 ± 0.9 with none in the immature group (p = 0.008). Mean number of MI oocytes was 5.6 ± 2.1 in the mature group and 1.0 ± 0.0 in the immature group (p = 0.008). The total number of retrieved oocytes was 8.8 ± 1.9 in the mature group and 2.0 ± 1.2 in the immature group (p = 0.008). The GCs of the mature group showed a significantly lower expression of hsa-let-7b compared to the GCs of the immature group (p < 0.001). Conclusion: Taken together, the miRNA expression profiles of human GCs obtained from dominant follicles are associated with maturity of the adjacent oocyte and may be useful as a prognosticator of IVF outcome.

Zusammenfassung

Hintergrund: Einige kürzlich unternommene Tierversuche haben gezeigt, dass die Regulierung der MicroRNA (miRNA) in Granulosazellen die meiotische Kompetenz von Eizellen beeinflusst. Aber die Unterschiede im Expressionsprofil der MiRNA von menschlichen Granulosazellen und deren Zusammenhang mit dem Reifungsgrad der Eizelle sind noch unzureichend geklärt. Ziel: Ziel dieser Beobachtungsstudie war es, zu untersuchen, ob es Unterschiede in den miRNA-Profilen menschlicher Granulosazellen gibt nach der kontrollierten ovariellen Stimulation für die In-vitro-Fertilisation (IVF). Methoden: In die Studie eingeschlossen wurden 10 Frauen, die mit GnRH-Agonisten zur ovariellen Stimulation behandelt wurden (langes Protokoll). Die Follikelflüssigkeit des dominanten Follikels wurde bei der Eizellentnahme ebenfalls abgesaugt. Die entnommenen Eizellen wurden je nach Reifegrad in 2 Gruppen unterteilt („ausgereifte Gruppe“ vs. „nicht ausgereifte Gruppe“). Es wurden dann Granulosazellen aus der Follikelflüssigkeit gesammelt und deren miRNA mit der Echtzeit-PCR-Methode analysiert. Ergebnisse: Die durchschnittliche Anzahl MII-Oozyten in der ausgereiften Gruppe betrug 1,6 ± 0,9, während die nicht ausgereifte Gruppe keine MII-Oozyten aufwies (p = 0,008). Die durchschnittliche Anzahl MI-Oozyten betrug 5,6 ± 2,1 in der ausgereiften Gruppe und 1,0 ± 0,0 in der nicht ausgereiften Gruppe (p = 0,008). Die Gesamtzahl entnommener Eizellen betrug 8,8 ± 1,9 in der ausgereiften Gruppe und 2,0 ± 1,2 in der nicht ausgereiften Gruppe (p = 0,008). Die Granulosazellen der ausgereiften Gruppe wiesen eine signifikant niedrigere Expression von hsa-let-7b auf verglichen mit den Granulosazellen der nicht ausgereiften Gruppe (p < 0,001). Schlussfolgerung: Die MiRNA-Expressionsprofile menschlicher Granulosazellen aus dominanten Follikeln korrelieren mit der Reife des Oozyten. Diese Erkenntnis könnte nützliche Hinweise für die Prognose hinsichtlich des Erfolgs einer IVF-Behandlung liefern.

Key words

microRNA - human granulosa cell - follicular fluid - oocyte maturation - in vitro fertilization

Schlüsselwörter

microRNA - menschliche Granulosazelle - Follikelflüssigkeit - Eireifung - In-vitro-Fertilisation

• References

• 1 Swain JE, Pool TB. ART failure: oocyte contributions to unsuccessful fertilization. Hum Reprod Update 2008; 14: 431-446
• 2 Zhang M, Su YQ, Sugiura K et al. Granulosa cell ligand NPPC and its receptor NPR2 maintain meiotic arrest in mouse oocytes. Science 2010; 330: 366-369
• 3 Russell DL, Robker RL. Molecular mechanisms of ovulation: co-ordination through the cumulus complex. Hum Reprod Update 2007; 13: 289-312
• 4 Adriaenssens T, Mazoyer C, Segers I et al. Differences in collagen expression in cumulus cells after exposure to highly purified menotropin or recombinant follicle-stimulating hormone in a mouse follicle culture model. Biol Reprod 2009; 80: 1015-1025
• 5 Pacella L, Zander-Fox DL, Armstrong DT et al. Women with reduced ovarian reserve or advanced maternal age have an altered follicular environment. Fertil Steril 2012; 98: 986-994.e1–2
• 6 Yerushalmi GM, Maman E, Yung Y et al. Molecular characterization of the human ovulatory cascade-lesson from the IVF/IVM model. J Assist Reprod Genet 2011; 28: 509-515
• 7 Gebhardt KM, Feil DK, Dunning KR et al. Human cumulus cell gene expression as a biomarker of pregnancy outcome after single embryo transfer. Fertil Steril 2011; 96: 47-52.e2
• 8 Bartel DP. MicroRNAs: target recognition and regulatory functions. Cell 2009; 136: 215-233
• 9 Ratner E, Lu L, Boeke M et al. A KRAS-variant in ovarian cancer acts as a genetic marker of cancer risk. Cancer Res 2010; 70: 6509-6515
• 10 Lee PD, Giudice LC, Conover CA et al. Insulin-like growth factor binding protein-1: recent findings and new directions. Proc Soc Exp Biol Med 1997; 216: 319-357
• 11 Lai EC. miRNAs: whys and wherefores of miRNA-mediated regulation. Curr Biol 2005; 15: R458-R460
• 12 Boutet S, Vazquez F, Liu J et al. Arabidopsis HEN1: a genetic link between endogenous miRNA controlling development and siRNA controlling transgene silencing and virus resistance. Curr Biol 2003; 13: 843-848
• 13 Poy MN, Eliasson L, Krutzfeldt J et al. A pancreatic islet-specific microRNA regulates insulin secretion. Nature 2004; 432: 226-230
• 14 Sokol NS, Ambros V. Mesodermally expressed Drosophila microRNA-1 is regulated by Twist and is required in muscles during larval growth. Genes Dev 2005; 19: 2343-2354
• 15 He L, Hannon GJ. MicroRNAs: small RNAs with a big role in gene regulation. Nat Rev Genet 2004; 5: 522-531
• 16 Kim YJ, Ku SY, Kim YY et al. MicroRNAs transfected into granulosa cells may regulate oocyte meiotic competence during in vitro maturation of mouse follicles. Hum Reprod 2013; 28: 3050-3061
• 17 Torley KJ, da Silveira JC, Smith P et al. Expression of miRNAs in ovine fetal gonads: potential role in gonadal differentiation. Reprod Biol Endocrinol 2011; 9: 2
• 18 Ozdegirmenci O, Dilbaz S, Cinar O et al. Can serum oestradiol be a predictor of quality of oocytes and embryos, maturation of oocytes and pregnancy rate in ICSI cycles?. Gynecol Endocrinol 2011; 27: 279-285
• 19 Moria A, Das M, Shehata F et al. Ovarian reserve and oocyte maturity in women with malignancy undergoing in vitro maturation treatment. Fertil Steril 2011; 95: 1621-1623
• 20 Otsuka M, Zheng M, Hayashi M et al. Impaired microRNA processing causes corpus luteum insufficiency and infertility in mice. J Clin Invest 2008; 118: 1944-1954
• 21 Miles JR, McDaneld TG, Wiedmann RT et al. MicroRNA expression profile in bovine cumulus-oocyte complexes: possible role of let-7 and miR-106a in the development of bovine oocytes. Anim Reprod Sci 2012; 130: 16-26
• 22 Christenson LK. MicroRNA control of ovarian function. Anim Reprod 2010; 7: 129-133
• 23 Assou S, Al-Edani T, Haouzi D et al. MicroRNAs: new candidates for the regulation of the human cumulus-oocyte complex. Hum Reprod 2013; 28: 3038-3049