Phosphoenolpyruvate carboxykinase and glucose-6-phosphatase are required for steroidogenesis in testicular Leydig cells.
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.
National Creative Research Initiatives Center for Nuclear Receptor Signals, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea.
Seung Won
SW
Ahn
Gil-Tae
GT
Gang
Surendar
S
Tadi
Balachandar
B
Nedumaran
Yong Deuk
YD
Kim
Ji Hoon
JH
Park
Gi Ryang
GR
Kweon
Seung-Hoi
SH
Koo
Keesook
K
Lee
Ryun-Sup
RS
Ahn
Yong-Hyeon
YH
Yim
Chul-Ho
CH
Lee
Robert A
RA
Harris
Hueng-Sik
HS
Choi
D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism; D057137:DAX-1 Orphan Nuclear Receptor / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005952:Glucose-6-Phosphatase / Q000096:biosynthesis* / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007985:Leydig Cells / Q000166:cytology / Q000201:enzymology*; D008297:Male; D051379:Mice; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000096:biosynthesis* / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism
D057137:DAX-1 Orphan Nuclear Receptor; C539965:NR0B1 protein, human; C082631:NR5A2 protein, human; C539966:Nr0b1 protein, mouse; C431936:Nr5a2 protein, mouse; D018160:Receptors, Cytoplasmic and Nuclear; D000242:Cyclic AMP; D055372:AMP-Activated Protein Kinases; D005952:Glucose-6-Phosphatase; D019764:Phosphoenolpyruvate Carboxykinase (ATP)