Sperm-borne microRNA-34c is required for the first cleavage division in mouse

Abstract

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.

Comparative profiling of small RNAs of pig seminal plasma and ejaculated and epididymal sperm

“…An early study suggested that sperm-borne miRNAs play a restricted role in mammalian fertilization (Amanai et al 2006); however, a subsequent study suggested that miRNAs play an important role in fertilization and pre-implantation embryonic development . In addition, based on the attenuation of the first cleavage division in vitro via the injection of a 'miR-34c inhibitor' into zygotes, Liu and coworkers suggested that miR-34c plays an essential role in the first cleavage division in mice (Liu et al 2012b). However, the validity of the function of miR-34c in vivo, as assessed using miR-34c-knockout mice, revealed that miR-34c is essential for normal spermatogenesis and male fertility, but its presence in sperm is dispensable for fertilization and pre-implantation development (Yuan et al 2015).…”

Postnatal consequences of assisted reproductive technologies in cattle

“…The sorting process damages spermatozoa so that fertilization rate in vitro is compromised (Wheeler et al, 2006;Rasmussen et al, 2013). Perhaps, reverse sorting reduces non-nuclear components of sperm that are delivered to the oocyte at fertilization, for example sperm-borne miRNA (Liu et al, 2012). Also, a possible delay in fertilization due to damaged sperm could conceivably result in oocyte aging, which has negative consequences for the oocyte and subsequent embryo (Agung et al, 2006;Koyama et al, 2014).…”

Molecular, cellular, and physiological determinants of bull fertility

“…Some of these biological processes include transport, signaling pathways, and cell protein modifications. Liu et al (32) discovered that the first embryonic cleavage in mice is directly dependent on the presence of miRNA34c, which is found mostly in mammalian sperm. Sperm transcripts can be detected using RNA sequencing (also known as deep sequencing or next generation sequencing) and by real-time reverse-transcriptase polymerase chain reaction.…”