Expression pattern and regulation of head-to-head genes Vps36 and Ckap2 during chicken follicle development

Vacuolar protein sorting 36(VPS36),a protein primarily known for its role in the Endosomal Sorting Complex Required for Transport pathway,has recently been shown to be linked to chicken reproduction.Previous research showed that Vps36 is significantly downregulated in sexually mature chicken ovaries compared to immature ones.In this study,using real-time quantitative RT-PCR,we investigated the expression pattern of Vps36 and its head-to-head gene Ckap2 mRNA in chicken follicles.Small white follicles were found to have significantly higher expression of Vps36 and Ckap2 mRNA than any other sized follicles(P<0.05).The expression of Vps36 and Ckap2 mRNA were detected in both granulosa and theca layers of pre-ovulatory follicles,the expression of Ckap2 in theca layers was slightly higher than in granulosa cells.Treatment of small yellow follicles with folliclestimulating hormone and estradiol resulted in a marked decrease of both Vps36 and Ckap2 mRNA(P<0.05);however,progesterone,transforming growth factor-β1 and luteinizing hormone induced no significant changes in Vps36 and Ckap2 mRNA expression in these follicles.These results indicate that the head-to-head genes of Vps36 and Ckap2 exhibit similar expression in chicken follicles and are involved in chicken follicle development.