Abstract
Meiosis-arrest female 1 (MARF1) is a recently identified key oogenic regulator essential for the maintenance of female fertility and genome integrity in mice. However, the detailed functions and the underlying mechanisms of MARF1 remain elusive. Here, in an attempt to create a mouse model expressing fluorescent protein-tagged MARF1 to facilitate further exploration of the roles of MARF1 in oocytes, we produced a Marf1-eGFP knockin (KI) mouse line in which the C-terminal structure and function of MARF1 were interfered by its fusing eGFP peptide. Using these Marf1-eGFP-KI mice, we revealed, unexpectedly, the functions of MARF1 in the control of oocyte meiotic division. We found that the Marf1-eGFP-KI females ovulated mature oocytes with severe meiotic and developmental defects, and thus were infertile. Moreover, meiotic reinitiation was delayed while meiotic completion was accelerated in the KI-oocytes, which was coincident with the increased incidence of oocyte aneuploidy. Therefore, MARF1 is indispensable for maintaining the fidelity of homolog segregation during oocyte maturation, and this function relies on its C-terminal domains.
Highlights
We serendipitously produced a Marf1-eGFP knockin (KI) mouse line, in which the Cterminal structure and function of the expressed Meiosis-arrest female 1 (MARF1) protein were interfered by its fusing eGFP peptide. By studying this line of mice, we unexpectedly revealed the indispensable role of MARF1 in the control of oocyte meiotic division
Western blot analysis showed that the oocytes of the mice carrying this knockin allele expressed the MARF1-eGFP fusion protein (Fig. 1C)
A single 174kDa band was detected in the sample of wild type (WT) oocytes, and a single larger band with the size of approximately 201 kDa was detected in the sample of Marf1eGFP-KI (MARF1-Fusion) oocytes
Summary
The success of reproduction necessitates the production of functionally normal eggs. Oocyte maturation is an essential step in producing a high-quality haploid egg which, upon fertilization, is competent to produce a diploid embryo and eventually gives rise to a healthy new individual. Grown oocytes of most mammalian species are arrested at the diplotene stage of the first meiotic prophase, which is most analogous to the G2 phase of the mitotic cell cycle division. At this stage, the oocyte has a large intact nucleus termed germinal vesicle (GV). The resumption of meiosis, equivalent to the mitotic G2/M transition[2], only takes place under the stimulation of the preovulatory LH surge or removal of oocytes from their follicular environment This process, commonly referred to as GV breakdown (GVB), is manifested by CLC number: R339.2+2, Document code: A The authors reported no conflict of interests.
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