Expression of an intracisternal A-particle-like element in rat ovary

We have isolated a rat intracisternal-A particle element (IAP)-like element (LAP-LE) from ovarian granulosa cells that appears to be identical to the rat EST clone AA964260. The compiled cDNA sequences contain several putativ e in-frame translation initiation codons with the largest capable of encodi ng a 365 amino acid protein with a reverse transcriptase domain in the N-te rminus as well as a bipartite nuclear localization signal sequence in the m iddle. Northern blotting shows a major similar to7 Kb transcript and a mino r similar to5 Kb transcript that are abundantly expressed in the ovary. In situ hybridization histochemistry using ovaries from gonadotropin-treated i mmature rats and regularly cycling adult rats show that this transcript is predominantly localized to granulosa cells of all healthy follicles, includ ing primary follicles, and to newly-formed and healthy corpora lutea. This cell-specific expression pattern of the IAP-LE gene is distinct from those of the several known retroviral elements, suggesting the potentially novel functional importance of the IAP-LE gene. Taken together, our results demon strate abundant and cell-specific expression of a novel IAP-LE in rat granu losa cells. (C) 2000 Academic Press.