Free Access
Reprod. Nutr. Dev.
Volume 45, Number 1, January-February 2005
Page(s) 101 - 108
Reprod. Nutr. Dev. 45 (2005) 101-108
DOI: 10.1051/rnd:2005007

Extracellular signal-regulated kinases (ERK) 1, 2 are required for luteinizing hormone (LH)-induced steroidogenesis in primary Leydig cells and control steroidogenic acute regulatory (StAR) expression

Nadine Martinat, Pascale Crépieux, Eric Reiter and Florian Guillou

Laboratoire de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique/Centre National pour la Recherche Scientifique/Université de Tours/Haras Nationaux, UMR 6175, Centre de Recherches de Tours, 37380 Nouzilly, France

(Received 2 July 2004; accepted 30 November 2004)

Abstract - The luteinizing hormone (LH) plays a critical role in steroidogenesis, by stimulating cAMP-dependent protein kinase A (PKA) and phospholipase A2 activity, and by mobilizing calcium and chloride ions. In contrast, whether the ERK 1, 2 mitogen-activated protein (MAP) kinases are involved in LH-induced steroidogenesis is less obvious. Here, we sought to clarify this point in rat primary Leydig cells, naturally bearing the LH receptor (LH-R) in male, and in the mouse tumoral Leydig cell line (MLTC 1). Pre-incubation of both cell types with the mitogen-activated protein kinase kinase (MEK) inhibitors U0126 and PD98059 reduced LH-induced steroidogenesis, and tonically enhanced the expression of the StAR protein. Furthermore, ERK1, 2 were inducibly phosphorylated following LH exposure of MLTC 1 cells. Altogether, our results indicate that in primary as well as in tumoral Leydig cells, inhibiting MEK dampened LH-induced steroidogenesis but enhanced basal as well as LH-induced StAR expression, suggesting that ERK1,2 could be involved in these responses.

Key words: LH / rat Leydig cells / steroidogenesis / MAP kinases / StAR

Corresponding author: Nadine Martinat

© INRA, EDP Sciences 2005