MicroRNA Let-7a and dicer are important in the activation and implantation of delayed implanting mouse embryos  

Oleh:

Ana, W.Y. Cheong ; Pang, Ronald T.K. ; Wei-Min, Liu ; Kottawatta, Kottawattage Sanda Arunika ; Kai-Fai, Lee ; Yeung, William S. B.

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: Human Reproduction vol. 29 no. 04 (Apr. 2014), page 750-762.
Topik: dicer; microRNA; embryo implantation; dormant blastocyst; estradiol activation

Ketersediaan

Perpustakaan FK Nomor Panggil: H07.K.2014.01 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

STUDY QUESTION Does Let-7a have a functional role in modulating dicer expression to activate dormant mouse blastocysts for implantation? SUMMARY ANSWER Let-7a post-transcriptionally regulates dicer expression altering microRNA expression to affect the implantation competency of the activated blastocysts. WHAT IS KNOWN ALREADY The Let-7a microRNA is up-regulated during blastocyst dormancy and its forced-expression suppresses embryo implantation in vitro and in vivo. Dicer is a Let-7 target, which processes pre-microRNA to mature microRNA. STUDY DESIGN, SIZE, DURATION The effects on the expression of Let-7a and dicer in dormant blastocysts during the first 12 h after estradiol-induced activation, and the relationship between Let-7a and dicer in preimplantation embryos were determined. The effects on the microRNA expression and embryo implantation in vivo in dicer-knockdown mouse 5–8 cell embryos and dormant blastocysts at 1 h post estradiol activation were also studied. PARTICIPANTS/MATERIALS, SETTING, METHODS ICR female mice at 6 weeks of age were ovariectomized on Day 4 of pregnancy to generate the delayed implantation model. Mouse 5–8 cell embryos and/or dormant blastocysts at 1 h after estradiol injection were electroporated with dicer siRNA and Let-7a precursor or Let-7a inhibitor. At 48 h post electroporation, the Let-7a expression, dicer transcripts and proteins in the embryos were determined using qPCR and immunostaining/western blotting, respectively. All experiments were repeated at least three times. MAIN RESULTS AND THE ROLE OF CHANCE Estradiol injection down-regulated Let-7a and up-regulated dicer in the dormant blastocysts during the first 12 h post-activation. Dicer knockdown at 1 h post-activation of blastocysts suppressed EGFR expression, attenuated EGF binding and compromised implantation of the transferred embryos. Let-7a transcriptionally regulated dicer by binding to the 3'-UTR of dicer in trophoblast cells. Dicer knockdown in blastocysts suppressed mature Let-7a expression and compromised implantation. LIMITATIONS, REASONS FOR CAUTION Gain- and loss-of-function approaches were used by analyzing transient expressions of transfected microRNA modulators or genes. The consequence of the Let-7a-dicer interaction on pregnancy remains to be determined. The study used the mouse as a model and the applicability of the observed phenomena in humans warrants further investigation. WIDER IMPLICATIONS OF THE FINDINGS Our results indicate that the Let-7a-dicer interaction leads to differential microRNA expression in dormant blastocysts after estradiol activation. Because the expression pattern of Let-7a in human blastocysts is similar to that in mouse blastocysts, our observation that the Let-7a-dicer interaction has a role in regulating the implantation potential of the mouse blastocysts could be applicable to humans.

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