New Enzymes Involved in the Mechanism of Action of Epidermal Growth Factor in a Clonal Strain of Leydig Tumor Cells.

CASTILLA, ROCÍO; GADALETA, MARIANA; CASTILLO, ANA FERNANDA; DUARTE, ALEJANDRA; NEUMAN, ISABEL; PAZ, CRISTINA; CORNEJO MACIEL, FABIANA; PODESTÁ, ERNESTO J

ENDOCRINOLOGY

Endocrine Society

Año: 2008 vol. 149 p. 3743 - 3752

0013-7227

The studies presented herein were designed to investigate the effect of mouse epidermal growth factor (mEGF) on arachidonic acid (AA) release in a clonal strain of cultured murine Leydig cells (designed MA-10). In MA-10 cells, mEGF promotes AA release and metabolization to lipoxygenated products, to induce the steroidogenic acute regulatory (StAR) protein. However, the mechanism by which mEGF releases AA in these cells is not totally elucidated. We show that mEGF produces an increment in the mitochondrial AA content in a short-term incubation (30 min). This AA is released by the action of a mitochondrial acyl-CoA thioesterase (Acot2), as demonstrated in experiments where Acot2 was down or overexpressed. This AA in turn, regulates the StAR protein expression, indirect evidence of its metabolization to lipoxygenated products. We also show that mEGF induces the expression (mRNA and protein) of Acot2 and of an acyl-CoA synthetase (ACS4) that provides the substrate, arachidonyl-CoA, to Acot2. This effect is also observed in another steroidogenic cell line, the adrenocortical Y1 cells. Taken together, our results show that i) mEGF can induce the generation of AA in a specific compartment of the cells i.e. the mitochondria, ii) mEGF can up-regulate ACS4 and Acot2 mRNA and protein levels iii) mEGF stimulated-intramitochondrial AA release leads to StAR protein induction.