Follicle microenvironment-associated alterations in gene expression in the mouse oocyte and its polar body

Abstract

Objective To determine whether the follicle environment modulates oocyte-specific gene transcript levels in cultured oocytes and polar bodies (PBs). Design Animal study. Setting Large academic research center. Animal(s) CD1 mice. Intervention(s) In vitro growth of secondary mouse follicles in 0.25% or 1.5% alginate (ALG) in a three-dimensional culture system. Main Outcome Measure(s) Relative transcript levels of Gdf9, Bmp15, Nlrp5, Tcl1, and Zp3 were measured by real-time quantitative reverse transcriptase–polymerase chain reaction in oocytes during in vitro follicle development and oocyte maturation and in their first PBs after removal from metaphase II (MII) eggs. Result(s) All transcripts decreased earlier in oocytes cultured in 1.5% ALG compared with 0.25% ALG. Transcript levels were lower in MII eggs cultured in 1.5% ALG compared with in 0.25% ALG. All genes were expressed in PBs, and transcript levels were lower in PBs cultured in 1.5% ALG compared with in 0.25% ALG. Abundance of all transcripts was lower in PBs than in their sibling oocytes. Conclusion(s) Local follicle environment modulates oocyte-specific gene expression in the oocyte and first PB. There is a significant difference in the transcript levels of oocyte-specific genes in PBs of 1.5% versus 0.25% ALG that correlates with ovarian environment-related decreases in oocyte competence.

Age-related increase in aneuploidy and alteration of gene expression in mouse first polar bodies

“…Their results demonstrated that detection and quantification of mRNA in human PBs is possible and that the human PB mRNA transcriptome reflects that of its sibling MII oocyte [9]. This work and our data demonstrated that PB 1 mRNA is being considered as a proxy for the oocyte [29].…”

Detection and quantification of maternal-effect gene transcripts in mouse second polar bodies: potential markers of embryo developmental competence

“…Our prior work quantified 6 maternal-effect mRNA transcripts in PB 1 from young and aged mouse MII oocytes and demonstrated that there is a significant difference in the transcript levels of oocyte-specific genes in aged vs. young PB that correlates with age-related decreases in oocyte competence (17). This study and our previous data led us to propose that a PB biopsy to measure maternal-effect mRNA abundance may serve as biomarkers of embryo competence (39). Future studies are needed to evaluate dynamic changes in mRNA turnover in PB 2 , as well as to identify a cohort of transcripts that are reliably detected in PB 2 , whose expression levels are predictive of the developmental competence of a given zygote and its resulting embryo.…”

Three-dimensional systems for in vitro follicular culture: overview of alginate-based matrices

“…Nevertheless, in this study the developmental competence of the oocytes was compromised by the high incidence of abnormal spindle formation and chromosome alignment. Variations in rigidity of the hydrogel also can affect the gene-expression pattern, as shown by Jiao and Woodruff (2013). Oocyte-specific gene-transcript levels in cultured oocytes and polar bodies were decreased in oocytes cultured in 1.5% alginate compared with 0.25% (Jiao and Woodruff 2013).…”