Involvement of clock gene expression, bone morphogenetic protein and activin in adrenocortical steroidogenesis by...

Area of Science:

• Endocrinology
• Chronobiology
• Molecular Biology

Background:

• The adrenal cortex regulates steroidogenesis, a process influenced by circadian rhythms.
• Clock genes play a crucial role in regulating physiological processes, including hormone production.

Purpose of the Study:

• To investigate the functional interactions between clock gene expression and adrenal steroidogenesis in human adrenocortical cells.
• To elucidate the regulatory mechanisms of clock genes in response to steroidogenic stimuli.

Main Methods:

• Utilized human adrenocortical H295R cells.
• Administered forskolin (FSK) to induce changes in gene expression.
• Employed siRNA to knock down Clock gene expression.
• Measured mRNA levels of clock genes (Bmal1, Clock, Per2, Cry1) and steroidogenic factors (StAR, CYP11B2, CYP17, HSD3B1).
• Investigated the effects of BMP-6, activin, and follistatin on Clock mRNA expression.

Main Results:

• Forskolin stimulation altered the expression of Bmal1, Clock, Per2, and Cry1 mRNA.
• Clock mRNA levels positively correlated with StAR mRNA levels.
• Clock gene knockdown significantly reduced FSK-induced StAR and CYP17 expression.
• BMP-6 and activin inhibited Clock mRNA expression, while follistatin increased it.

Conclusions:

• Clock gene expression is dynamically regulated by factors like FSK, BMP-6, and activin in human adrenocortical cells.
• Clock gene expression, particularly Clock, is tightly linked to the regulation of StAR expression and subsequent steroidogenesis.
• These findings suggest an intricate interplay between circadian machinery and adrenal steroid hormone production.