Cooperation of luteinizing hormone signaling pathways in preovulatory avian follicles regulates circadian clock expression in granulosa cell.
Ovulation in birds is triggered by a surge of luteinizing hormone (LH), and the ovulatory cycle is affected by the circadian rhythms of clock genes transcription levels in follicles. The influence of LH signaling cascades action on circadian clock genes was investigated using granulosa cells of preovulatory follicles from Roman hens cultured in a serum-free system. The expression of core oscillators (Bmal1, Clock, Cry1, Per2, and Rev-erbβ), clock-controlled gene (Star), Egr-1 and LHr was measured by quantitative real-time PCR. Significant changes in clock genes transcription levels were observed in control groups over 24 h, indicating that cell-autonomous rhythms exist in granulosa cells. Intriguingly, the transcript levels of clock genes increased with LH treatment during 24 h of culture; they peaked 4 h in advance of controls and second but weaker oscillations were also observed. It appeared that LH changed the cell-autonomous rhythm and cycle time of clock genes. To further investigate the LH signaling cascades, inhibitors of cyclic adenosine monophosphate (cAMP), p38 mitogen-activated protein kinases (p38MAPK) and extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathways were used. The transcript levels of clock genes were suppressed by blocking cAMP, but increased with similar expression patterns by blocking the p38MPAK and ERK1/2 pathways over 24 h. Thus, the influence of LH signaling cascades in chicken ovulation is mediated by the cAMP pathway and also involves the p38MAPK and ERK1/2 pathways.
Laboratory of Animal Genetic and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Ya'an, 625014, Sichuan, China.
Liang
L
Li
Zhichao
Z
Zhang
Jiyun
J
Peng
Yagang
Y
Wang
Qing
Q
Zhu
D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D002940:Circadian Rhythm / Q000187:drug effects*; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D030762:Estrous Cycle; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D056925:Circadian Rhythm Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases