CHANGES IN THE GENE-EXPRESSION OF A PROTEIN WITH THE CDC10 SWI6 MOTIF, V-1, DURING RAT FOLLICULAR DEVELOPMENT AND CORPUS-LUTEUM FORMATION/

We examined the gene expression of V-1, a novel soluble protein with t he cdc10/SWI6 motif, in pseudopregnant rat ovaries. Northern blot anal ysis on days 1, 5, and 11 of pseudopregnancy revealed an approximately 2-fold increase in the V-1 messenger RNA (mRNA) expression level on d ay 5 to that on day 1, and no significant change was observed between those on day 5 and day 11. An injection of human CG on day 5 further i ncreased the V-1 mRNA level to about 1.6-fold of that of the untreated control. Western blot analysis showed higher V-1 protein expression o n days 5 and 11 of pseudopregnancy than that on day 1. In situ hybridi zation and immunohistochemistry with ovaries on day 3 of pseudopregnan cy showed that luteal cells of corpora lutea and also cells of the coe xisting follicles including oocytes express V-1 mRNA and the protein, with apparent rank order of the expression: oocytes > luteal cells > f ollicular cells >> atretic follicular cells including oocytes. These d ata indicate the dynamic change in the V-1 gene expression in the ovar ian steroidogenic cells and oocytes and suggest potential roles of the V-1 protein in ovarian functions including corpus luteum formation an d folliculogenesis.