HIF1 is dispensable for oocyte development and female fertility in mice.

BACKGROUND

It has been thought that oocyte may develop in a low oxygen environment, as changes in follicle structure and formation of a fluid-filled antrum. The survival of hypoxic tissues is controlled by hypoxia-inducible factors (HIFs) that are activated in a low oxygen state. HIF1 is expressed in mature mouse oocytes and continues to be expressed after fertilization, from the 2-cell to blastocyst stage. However, the physiological roles of HIF pathway during oogenesis and embryogenesis have still not been elucidated in detail.

METHODS

Mutant mice with oocyte-specific HIF1 deletion were generated by crossing 1 mice with transgenic mice expressing -promoter-mediated Cre recombinase. Breeding assay was carried out to detect female fertility. fertilization and embryo culture were used to assess early embryo development. Oocyte meiotic progression was also examined. Quantitative RT-PCR was used for analyzing of candidate genes expression.

RESULTS

We successfully generated mutant mice with oocyte-specific deletion of HIF1. Oocytes loss of HIF1 did not affect female fertility, ovulation and early embryo development. Moreover, oocytes can mature in vitro, and form well-organized spindle in the absence of HIF1. In addition, pronounced differences in and mRNA expression were not observed in HIF1-deleted oocytes. These results revealed that HIF pathway in oocytes is not essential for female fertility.