Synchronization of circadian clock gene expression in cultured granulosa cells from hen preovulatory follicles
PURPOSE:
Understand how granulosa cells function in a circadian manner.
ISSUE:
How does the normal circadian rhythm in granulosa cells work, and what would happen in the absence of clock and clock-related genes?
BACKGROUND:
Granulosa cells:
- Are differentiated and non-proliferative in preovulatory follicles.
- Differentiation is determined by:
- Ability to generate cyclic adenosine monophosphate in response to gonadotropins;
- Progesterone production
Clock and clock-related genes:
Have a timing effect in a biological cycle.
- Bmal1 - Promotes Per2 transcription in granulosa cells.
- Per2 - Prevents its own production by Bmal1 when it becomes accumulated.
- Id2 - Promotes differentiation in granulosa cells, and competes with Bmal1 for promoter region of Per2.
HYPOTHESES:
- Do granulosa cells from preovulatory hen follicles exhibit in vivo circadian rhythms of clock and clock-related genes, including Per2, Bmal1, Dec1 and Id2?
- Are these genes able to control the time in which ovulation occurs?
OBJECTIVES:
- Establish a role for granulosa cell circadian rhythms in the timing of ovulation
- Determine if Id2 is a clock gene regulator.
RESULTS:
- Per2, Dec1 and Bmal1 gene expression in preovulatory follicle granulosa cells
- Granulosa cells have a rhythmic expression of Per2 and Bmal1 when synchronized by serum shock.
- Per2 and Bmal1 are able to induce a circadian rhythm in granulosa cells.
- Per2 and Bmal1 may have a timing effect on ovulation and oviposition.
SIGNIFICANCE:
- Reproductive enhancement of threatened and domesticated avian species.
- Better understanding and improvement of women's reproductive health.
CURRENT AND FUTURE STUDIES:
Determine the effect of LH, TGF-β, BMP6 and Id proteins on the synchronization of clock gene expression in granulosa cells.
Currently: Will be studying Veterinary and Equine Technology at Murray State (Murray, Kentucky), Fall 2013
