Hormonal regulation and function of an RNA helicase, Ddx5 in corpus luteum of adult Wistar rats

Abstract

Corpus luteum (CL) is an endocrine tissue involved in regulation of reproductive cycle and early pregnancy establishment. In the present study DEAD-box helicase-5 (Ddx5), a member of the DEAD box family of RNA helicases was investigated for its expression, regulation and function in CL of Wistar rats. Ddx5 was expressed in adult rat CL. Primary cell culture from supra-ovulated ovaries were established for in vitro studies. Addition of luteinizing hormone (LH; 100 ng/ml), a luteotrophic factor in primary cell culture, decreased Ddx5 RNA expression (foldchange:0.6 ± 0.075) while prostaglandin alpha (PGF2α; 1μM), a luteolytic factor caused an increase (foldchange:2.4 ± 0.4) compared to control group. Under in vivo conditions, the administration of PGF2α or gonadotropin-releasing hormone antagonist; cetrorelix (CET) caused luteolysis as well as an increase in the protein level of Ddx5 (foldchange:1.9 ± 0.27 and 1.4 ± 0.09 viz.; p < 0.05) in CL of adult rats. LH was administered post CET treatment which suppressed Ddx5 protein expression (foldchange:0.8 ± 0.16; p < 0.05) compared to CET treated group. Further, it was observed that the expression of Ddx5 was upregulated (foldchange:1.5 ± 0.23; p < 0.05) in CL during late pregnancy compared to mid pregnancy concomitant to luteolysis in adult rats. Overall, the results suggest for the first time that Ddx5 is expressed in rat CL and regulated by luteolytic and luteotrophic factors in an inverse fashion. Further, the data significantly correlates ddx5 expression to CL regression suggesting involvement of ddx5 in luteolysis. These results suggest a significant role of Ddx5 in female reproduction biology and warrant in depth examination of the function of Ddx5 in CL.