Sperm-borne microRNA-34c is required for the first cleavage division in mouse.
In mammals, the sperm deliver mRNA of unknown function into the oocytes during fertilization. The role of sperm microRNAs (miRNAs) in preimplantation development is unknown. miRNA profiling identified six miRNAs expressed in the sperm and the zygotes but not in the oocytes or preimplantation embryos. Sperm contained both the precursor and the mature form of one of these miRNAs, miR-34c. The absence of an increased level of miR-34c in zygotes derived from α-amanitin-treated oocytes and in parthenogenetic oocytes supported a sperm origin of zygotic miR-34c. Injection of miR-34c inhibitor into zygotes inhibited DNA synthesis and significantly suppressed first cleavage division. A 3' UTR luciferase assay and Western blotting demonstrated that miR-34c regulates B-cell leukemia/lymphoma 2 (Bcl-2) expression in the zygotes. Coinjection of anti-Bcl-2 antibody in zygotes partially reversed but injection of Bcl-2 protein mimicked the effect of miR-34c inhibition. Oocyte activation is essential for the miR-34c action in zygotes, as demonstrated by a decrease in 3'UTR luciferase reporter activity and Bcl-2 expression after injection of precursor miR-34c into parthenogenetic oocytes. Our findings provide evidence that sperm-borne miR-34c is important for the first cell division via modulation of Bcl-2 expression.
Department of Obstetrics and Gynaecology and Centre for Reproduction, Development and Growth,  University of Hong Kong, Pokfulam, Hong Kong,  People's Republic of China.
Wei-Min
WM
Liu
Ronald T K
RT
Pang
Philip C N
PC
Chiu
Benancy P C
BP
Wong
Kaiqin
K
Lao
Kai-Fai
KF
Lee
William S B
WS
Yeung
D053959:Alpha-Amanitin / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D004261:DNA Replication / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D008156:Luciferases; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D013094:Spermatozoa / Q000737:chemistry*
D053959:Alpha-Amanitin; C551848:MIRN34a microRNA, mouse; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; D008156:Luciferases