Corticosterone biosynthesis in mouse clonal myoblastic C2C12 cells.

Area of Science:

• Endocrinology
• Muscle Physiology
• Steroidogenesis

Background:

• Corticosterone (CORT) is a major glucocorticoid regulating stress responses and energy metabolism.
• While local sex steroid synthesis in muscle is known, local CORT synthesis remains unconfirmed.
• Investigating local CORT synthesis in skeletal muscle is crucial for understanding its role beyond adrenal secretion.

Purpose of the Study:

• To investigate the potential for local corticosterone (CORT) synthesis in skeletal muscle cells.
• To identify key enzymes and substrates involved in CORT production within C2C12 myoblastic cells.
• To determine if C2C12 cells possess the enzymatic machinery for steroidogenesis.

Main Methods:

• Utilized a clonal myoblastic cell line (C2C12) for investigating steroidogenic activities.
• Employed LC-MS/MS analysis to detect enzymatic reaction products of CORT synthesis enzymes.
• Assessed the impact of pregnenolone-sulfate conjugate addition on pregnenolone levels over time.

Main Results:

• Identified three key enzymes (3ß-HSD, CYP21, CYP11ß) involved in CORT synthesis within C2C12 cells.
• Detected pregnenolone and observed increased levels upon addition of pregnenolone-sulfate conjugates.
• Confirmed the presence of steroidogenic activity but noted the absence of a cholesterol-cleaving enzyme.

Conclusions:

• Corticosterone (CORT) synthesis occurs in C2C12 skeletal muscle cells.
• Pregnenolone-sulfate conjugates are suggested as the initial substrate for local CORT steroidogenesis in muscle.
• This finding opens new avenues for research into local hormone regulation in skeletal muscle.