Year-end Sale % OFF 
Abstract
Meiotically arrested oocytes are characterized by the presence of the nuclear structure known as germinal-vesicle (GV), the breakdown of which (GVBD) is associated with resumption of meiosis. Fyn is a pivotal factor in resumption of the first meiotic division; its inhibition markedly decreases the fraction of oocytes undergoing GVBD. Here, we reveal that in mouse oocytes Fyn is post-transcriptionally regulated by miR-125a-3p. We demonstrate that in oocytes resuming meiosis miR-125a-3p and Fyn exhibit a reciprocal expression pattern; miR-125a-3p decreases alongside with an increase in Fyn expression. Microinjection of miR-125a-3p inhibits GVBD, an effect that is markedly reduced by Fyn over-expression, and impairs the organization of the actin rim surrounding the nucleus. Lower rate of GVBD is also observed in oocytes exposed to cytochalasin-D or blebbistatin, which interfere with actin polymerization and contractility of actin bundles, respectively. By down-regulating Fyn in HEK-293T cells, miR-125a-3p reduces the interaction between actin and A-type lamins, which constitute the nuclear-lamina. Our findings suggest a mechanism, by which a decrease in miR-125a-3p during oocyte maturation facilitates GVBD by allowing Fyn up-regulation and the resulting stabilization of the interaction between actin and A-type lamins.
Highlights
Meiosis of mammalian oocytes begins during embryonic life when oogonia enter the first meiotic division and arrest at the diplotene stage of the first prophase, characterized by the presence of a prominent nucleus, known as the germinal vesicle (GV)
The expression of Fyn significantly increased during the transition from GV to GV breakdown (GVBD) (p = 0.001) and was followed by another significant increase at the meiotic division (MII) stage (p = 0.001)
These findings may suggest that Fyn, previously shown by us to participate in the control of oocyte maturation[3], is post-transcriptionally regulated by miR-125a-3p in mouse fully grown GV oocytes
Summary
The expression profile of miR-125a-3p and Fyn during oocyte maturation. To characterize the expression profile of miR-125a-3p and Fyn throughout oocyte maturation, mouse oocytes, at various stages of meiosis (GV, GVBD and MII) were lysed and their RNAs and proteins were extracted and subjected to qPCR and WB, respectively. We hypothesized that the depolymerization of cytoplasmic actin filaments and of nuclear actin rim, observed in miR-125a-3p over-expressing GV oocytes, interferes with the interaction between actin and A-type lamins and may account for the inhibitory effect of miR-125a-3p on GVBD. Fyn interacts with several cytoskeletal proteins[24] and co-localizes with actin in GV and MII mouse oocytes[6] This observation led us to examine whether Fyn is bound to actin filaments with no dependency on A-type lamins.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
