Phosphoenolpyruvate Carboxykinase and Glucose-6-phosphatase Are Required for Steroidogenesis in Testicular Leydig Cells

• Published in: The Journal of biological chemistry 2012-12, Vol.287 (50), p.41875-41887
• Main Authors: Ahn, Seung Won, Gang, Gil-Tae, Tadi, Surendar, Nedumaran, Balachandar, Kim, Yong Deuk, Park, Ji Hoon, Kweon, Gi Ryang, Koo, Seung-Hoi, Lee, Keesook, Ahn, Ryun-Sup, Yim, Yong-Hyeon, Lee, Chul-Ho, Harris, Robert A., Choi, Hueng-Sik
• Format: Article
• Language: English
• Subjects: AMP-activated Kinase (AMPK); AMP-Activated Protein Kinases - genetics; AMP-Activated Protein Kinases - metabolism; Animals; Cyclic AMP (cAMP); Cyclic AMP - genetics; Cyclic AMP - metabolism; DAX-1; DAX-1 Orphan Nuclear Receptor - genetics; DAX-1 Orphan Nuclear Receptor - metabolism; Gene Expression Regulation, Enzymologic - physiology; Gene Regulation; Glucose-6-Phosphatase - biosynthesis; Glucose-6-Phosphatase - genetics; HeLa Cells; Humans; Leydig Cells - cytology; Leydig Cells - enzymology; Male; Mice; Nuclear Receptors; Phosphoenolpyruvate Carboxykinase; Phosphoenolpyruvate Carboxykinase (ATP) - biosynthesis; Phosphoenolpyruvate Carboxykinase (ATP) - genetics; Promoter Regions, Genetic - physiology; Receptors, Cytoplasmic and Nuclear - genetics; Receptors, Cytoplasmic and Nuclear - metabolism; Steroidogenesis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.421552

Cyclic AMP (cAMP) induces steroidogenic enzyme gene expression and stimulates testosterone production in Leydig cells. Phosphoenolpyruvate carboxykinase (PEPCK) is expressed in Leydig cells, but its role has not been defined. In this study, we found that PEPCK and glucose-6-phosphatase (Glc-6-Pase) are increased significantly following cAMP treatment of mouse Leydig cells. Moreover, cAMP treatment increased recruitment of the cAMP-response element-binding transcription factor and decreased recruitment of the corepressor DAX-1 on the pepck promoter. Furthermore, cAMP induced an increase in ATP that correlated with a decrease in phospho-AMP-activated protein kinase (AMPK). In contrast, knockdown or inhibition of PEPCK decreased ATP and increased phospho-AMPK. Treatment with an AMPK activator or overexpression of the constitutively active form of AMPK inhibited cAMP-induced steroidogenic enzyme promoter activities and gene expression. Liver receptor homolog-1 (LRH-1) was involved in cAMP-induced steroidogenic enzyme gene expression but was inhibited by AMPK activation in Leydig cells. Additionally, inhibition or knockdown of PEPCK and Glc-6-Pase decreased cAMP-mediated induction of steroidogenic enzyme gene expression and steroidogenesis. Finally, pubertal mouse (8-week-old) testes and human chorionic gonadotropin-induced prepubertal mouse testes showed increased PEPCK and Glc-6-Pase gene expression. Taken together, these results suggest that induction of PEPCK and Glc-6-Pase by cAMP plays an important role in Leydig cell steroidogenesis. Background: PEPCK is expressed in Leydig cells of testes, but its role has not been studied. Results: Knockdown and inhibition of PEPCK and Glc-6-Pase inhibited steroidogenesis via activation of AMPK. Conclusion: PEPCK and Glc-6-Pase are required for steroidogenesis in testicular Leydig cells. Significance: Male fertility may be adversely affected by conditions and factors that inhibit PEPCK and Glc-6-Pase expression in Leydig cells.