Expression of cell cycle regulatory genes during primordial-primary follicle transition in the mouse ovary

To elucidate the genes involved in the ovarian primordial-primary follicle transition.

Experimental animal study.

Research unit of university.

Day-1 and day-5 female ICR strain mice.

We conducted forward and reverse suppression subtractive hybridization using ovarian mRNAs from day-1 and day-5 mice.

After subtractive hybridization, the differential expression of certain genes between day-1 and day-5 ovaries was confirmed by Northern blot analysis. Differential expression of genes between primordial and primary follicles that are involved in the cell-cycle regulation was confirmed by laser capture microdissection (LCM) of follicles followed by real-time polymerase chain reaction (PCR).

In toto, 347 clones were sequenced and analyzed with the BLAST and RIKEN programs. Sequences of 312 clones significantly matched database entries, and 35 clones were novel. Among them, differential expression of five genes between day-1 and day-5 ovaries was confirmed by Northern blot analysis. In addition, differential expression between primordial and primary follicles of 11 more genes, particularly related to the cell-cycle regulation, was confirmed using LCM followed by real-time PCR.

We reported the ovarian expression of many cell-cycle regulating genes during the primordial-primary follicle transition process. Results of the present study may provide insight for further study of the molecular mechanism(s) involved in primordial-primary follicle transition.