The Signal Transduction System in Luteotrophic Stimulation of Expression of the 3β-HSD Gene in Porcine Granulosa Cells in Culture
The enzyme 3β-hydroxy-\( \Delta \) 5-steroid dehydrogenase (3β-HSD) catalyses the formation of \( \Delta \) 4-3ketosteroids from \( \Delta \) 5-ene, 3β-hydroxysteroids (1). Because it converts pregnenolone to progesterone, it is central to the production of steroid hormones. In rat granulosa cells, follicle stimulating hormone (FSH) and human chorionic gonadotropin (hCG), which stimulate steroidogenesis, increase the velocity of 3β-HSD, while gonadotrophin releasing hormone, which inhibits steroidogenesis, reduces the velocity, but the Km is unaffected by these hormones (2, 3). In this chapter, we discuss evidence that in luteinized cultured pig granulosa cells, luteotrophins and cAMP induce an increase in 3β-HSD mRNA levels that can be inhibited by the activation of protein kinase C.
KeywordsGranulosa Cell Signal Transduction System Luteal Tissue Porcine Granulosa Cell Dibutyryl Adenosine
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