Submitted May 17, 2008
Returned for revision June 14, 2008
Accepted July 28, 2008
Minireview
Oocyte-Specific Knockout: a Novel In Vivo Approach for Studying Gene Functions During Folliculogenesis, Oocyte Maturation, Fertilization, and Embryogenesis
Qing-Yuan Sun ,
Kui Liu ,
and
Kazuhiro Kikuchi *
* To whom correspondence should be addressed. E-mail: kiku{at}nias.affrc.go.jp.
Abstract
Knockout mice have been used as most useful tools in helping us understand the functional roles of specific genes in development and diseases. However, in many cases, knockout mice are embryonic lethal which prevents investigations into a number of important questions, or they display developmental abnormalities including fertility defects. In contrast, conditional knockout, which is achieved by the Cre-LoxP system, can be used to delete a gene in a specific organ, tissue, or at a specific developmental stage. This technique has advantages over conventional knockout, especially when conventional knockout causes embryonic lethality or when functions of maternal transcripts in early development need to be defined. Recently, to specifically delete genes of interest in oocytes, crossing Zp3-Cre or Gdf9-Cre transgenic mouse lines, in which Cre-recombinase expression is driven by oocyte-specific zona pellucida 3 (Zp3) promoter or growth differentiation factor 9 (Gdf9) promoter, with mice bearing floxed target genes, has been widely used. The novel in vivo approach has helped to understand the functions of specific genes in folliculogenesis/oogenesis, oocyte maturation, fertilization and embryogenesis. In this mini-review, recent advances in understanding the molecular mechanisms regulating major reproductive and developmental events as revealed by oocyte-specific conditional knockout, and perspectives of this technology to related studies are discussed.
Key words:
Embryo •
Gamete Biology •
Fertilization •
Follicular development •
Meiosis
