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The role of microRNAs in regulation of mammalian oocyte and embryo development
Marcollová, Kateřina ; Procházka, Radek (advisor) ; Svoboda, Petr (referee)
Cumulus-oocyte complex (COCs) is crucial for mammalian reproduction. Cumulus cells not only nurture the oocyte; they also represent important communicational nodes for mediating information towards and from the oocyte. The non-coding miRNAs can modulate posttranscriptional events they might serve as a useful biomarker for evaluating cell conditions. Based on the COCs staining with vital Lissamine Green B stain we divided cumulus cells into high- and low-quality ones. Furthermore, we implemented division based on the maturation stage, the GV and MII. Sequencing data analysis showed that DE miRNAs from qualitatively different stages donot significantly vary. Nonetheless, significantly DE miRNAs were detected between two developmentally different stages. We identified e.g. ssc-miR-183, ssc-miR-182, and ssc-miR-21-5p to be highly downregulated when comparing GV to MII stage. Among the highly expressed miRNAs from all samples were members of let-7 family (let-7c, let-7a, let- 7f-5p), ssc-miR-16, ssc-miR-21-5p, and ssc-miR-125a. Targeted genes by the DE miRNAs were involved in ErbB, TGF-β, MAPK, FoxO, gap junction and cGMP signalling pathways. We conclude that single miRNAs in cumulus cells probably cannot be used as a reliable oocyte quality marker. On the other hand,changes in the miRNA expression in...
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The role of growth factors and cytokines in regulation of mammalian oocyte maturation
Marcollová, Kateřina ; Procházka, Radek (advisor) ; Vávra, Jiří (referee)
Reproduction is key for species survival. Oocytes are blocked in prophase I of meiosis in follicle. Gonadotropin stimulation leads to follicle growth and competent oocyte. First polar body extrusion is a sign of meiotic division resumption. Oocyte is blocked at prophase I by a high cAMP level, activating PKA, that inhibits MPF. CNP binds to NPR2, that stimulates the generation of cGMP in granulosa cells, which diffuses to oocyte where it competes with cAMP on PDE3A. LH and FSH released from pituitary gland initiates signaling cascade restoring meiotic division. Synthesis of AREG, EREG and BTC activates EGFR and MAPK pathways in somatic cells which contribute to reduction of gap junction permeability, lowering NPR2 activity, that leads to reduction of cGMP production and transport. Less cGMP diffuses to oocytes, which leads to PDE3A activation and cAMP hydrolysis. This causes MPF activation and meiotic division resumption. MAPK together with PI3K participate on increasing production of hyaluronic acid, thereby cumulus cells expansion and oocyte ovulation. Oocyte maturation and growth is improved with utilization of in vitro technics and oocyte cultivation with growth factors and cytokines. FLI medium, combining FGF2, LIF and IGF-1, increases oocyte cultivation success and blastocyst quality of farm...
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