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Inducible expression of protein kinase Calpha suppresses steroidogenesis in Y-1 adrenocortical cells

M E Reyland1, D L Williams, E K White

  • 1Department of Basic Science and Oral Research, School of Dentistry, University of Colorado, Health Sciences Center, Denver, Colorado 80262, USA.

The American Journal of Physiology
|September 9, 1998
PubMed

Insights

Protein kinase C alpha (PKCalpha) suppresses steroidogenesis in Y-1 cells by reducing P450-SCC activity. This specific isoform, PKCalpha, plays a key role in regulating adrenal steroid production.

Area of Science:

  • Cell Biology
  • Endocrinology
  • Biochemistry

Background:

  • Protein kinase C (PKC) is known to suppress steroidogenesis in Y-1 adrenocortical cells.
  • The specific PKC isoform responsible for this suppression has not been identified.

Purpose of the Study:

  • To determine if the PKCalpha isoform mediates the suppression of steroidogenesis in Y-1 cells.
  • To investigate the role of PKCalpha in regulating P450 cholesterol side-chain cleavage enzyme (P450-SCC) activity.

Main Methods:

  • Developed Y-1 cell lines with tetracycline-regulated PKCalpha expression.
  • Assessed P450-SCC activity by measuring hydroxycholesterol to pregnenolone conversion.
  • Utilized a P450-SCC promoter-luciferase construct to evaluate transcriptional regulation.
  • Analyzed 12 Y-1 subclones to correlate endogenous PKC activity with steroidogenesis.

Main Results:

  • Increased PKCalpha expression decreased P450-SCC activity and P450-SCC promoter-luciferase activity.
  • PKCalpha expression did not affect 8-bromo-cAMP-induced steroidogenesis, indicating independent pathways.
  • Steroid production in Y-1 subclones inversely correlated with total PKC activity and PKCalpha expression, but not PKCepsilon or PKCzeta.

Conclusions:

  • PKCalpha is the specific isoform that suppresses steroidogenesis in Y-1 adrenocortical cells.
  • PKCalpha regulates steroidogenesis by modulating P450-SCC activity.
  • These findings elucidate a novel regulatory mechanism in adrenal steroid production.

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