Abstract
Oocytes are recognized as a source of regulatory molecules that influence follicular development through an array of actions on granulosa cells. Recently, more and more hormones and signaling molecules were identified during follicular developmental processes; however, the details about their functions are still unclear. During efforts to clone follicular development‐related genes, we isolated a cDNA fragment by DDRT‐PCR. To obtain cDNA 5′‐ and 3′‐end sequences, we screened a mouse ovarian cDNA library. After screening the library, an open reading frame of 2,994 bp for the new gene (Oocyte‐G1), which encodes a 997‐residue protein, was cloned. Northern blot analysis revealed the presence of ∼3.6 kb Oocyte‐G1 mRNA in ovary, lung, kidney, testis and brain. Northern analysis of RNA from ovaries in vivo showed that Oocyte‐G1 was weakly expressed on day 5 and at a moderate level on day 10. Thereafter, on day 15 or in adults (day 40), there was an increase in expression, followed by a decline in ovaries on day 20 or older (day 120). Furthermore, we studied the Ooctye‐G1 protein by using the antiserum against a peptide sequence unique to this gene in Western blotting and immunolocalization. The antiserum recognized a prominent band of ∼110 kDa in immunoblots and signals were dispersed in oocytes and some cumulus granulosa cells. Our results suggest the potential role of Oocyte‐G1 in ovarian follicular development. J. Cell. Physiol. 218: 75–83, 2009. © 2008 Wiley‐Liss, Inc.