Calcium-dependent mitochondrial cAMP production enhances aldosterone secretion

Area of Science:

• Endocrinology
• Cell Biology
• Biochemistry

Background:

• Aldosterone secretion by glomerulosa cells is regulated by Ca(2+) and cAMP signaling pathways.
• A novel interaction involves Ca(2+)-induced cAMP formation within the mitochondrial matrix.

Purpose of the Study:

• To investigate the role of soluble adenylyl cyclase (sAC) in mitochondrial cAMP production.
• To determine the impact of mitochondrial cAMP on angiotensin II-stimulated aldosterone synthesis.

Main Methods:

• Utilized H295R adrenocortical cells and a mitochondria-targeted fluorescent sensor (4mtH30) for cAMP monitoring.
• Employed sAC inhibitor (2-OHE), RNA interference, PDE2A inhibitor, and S100G expression.
• Measured aldosterone production following angiotensin II stimulation.

Main Results:

• Soluble adenylyl cyclase (sAC) is expressed in H295R cells and contributes to mitochondrial cAMP formation.
• Angiotensin II significantly increased mitochondrial cAMP, an effect modulated by HCO3(-), sAC activity, and PDE2A.
• Inhibition or knockdown of sAC markedly reduced angiotensin II-induced aldosterone production.

Conclusions:

• This research provides the first evidence for a cell-specific, functional role of mitochondrial cAMP in regulating aldosterone secretion.
• Soluble adenylyl cyclase (sAC) within the mitochondria is a key mediator of angiotensin II-stimulated aldosterone production.