Ski protein is implicated in proliferation/differentiation in a variety of cells. We had previously reported that Ski protein is present in granulosa cells of atretic follicles, but not in preovulatory follicles, suggesting that Ski has a role in apoptosis of granulosa cells. The alternative fate of granulosa cells other than apoptosis is to differentiate to luteal cells, however, it is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of the present study was to locate Ski protein in the rat ovary during luteinization to predict the possible role of Ski. In order to examine the expression pattern of Ski protein along with the progress of luteinization, follicular growth was induced by administration of equine chorionic gonadtropin to immature female rat, and luteinization was induced by human chorionic gonadtropin treatment to mimic luteinizing hormone (LH) surge. While no Ski-positive granulosa cells were present in preovulatory follicle, Ski protein expression was induced in response to LH surge, and was maintained after the formation of corpus luteum (CL). Though Ski protein is absent in granulosa cells of preovulatory follicle, its mRNA (c-ski) was expressed and the level was unchanged even after LH surge. Taken together, these results demonstrated that Ski protein expression is induced in granulosa cells upon luteinization, and suggested that its expression is regulated post-transcriptionally.

INTRODUCTION   MATERIALS AND METHODS    Animals    Hormone Assay    Immunohistochemistry and TUNEL Staining    qPCR (Real Time PCR)    Statistical Analysis   RESULTS   DISCUSSION   REFERENCES

• Hyun Kim(Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Animal Genetic Resources Station, National Institute of Animal Science, RDA) Corresponding author
• Takashi Matsuwaki(Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo)
• Keitaro Yamanouchi(Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo)
• Masugi Nishihara(Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo)
• Sungwoo Kim(Animal Genetic Resources Station, National Institute of Animal Science, RDA)
• Yeoung-Gyu Ko(Animal Genetic Resources Station, National Institute of Animal Science, RDA)
• Boh-Suk Yang(Animal Genetic Resources Station, National Institute of Animal Science, RDA)