New enzymes involved in the mechanism of action of epidermal growth factor in a clonal strain of Leydig tumor cells.
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 metabolism 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 in which Acot2 was down or overexpressed. This AA in turn regulates the StAR protein expression, indirect evidence of its metabolism to lipoxygenated products. We also show that mEGF induces the expression (mRNA and protein) of Acot2 and an acyl-CoA synthetase 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: 1) mEGF can induce the generation of AA in a specific compartment of the cells, i.e. the mitochondria; 2) mEGF can up-regulate acyl-CoA synthetase and Acot2 mRNA and protein levels; and 3) mEGF-stimulated intramitochondrial AA release leads to StAR protein induction.
Castilla
Rocío
R
Instituto de Investigaciones Moleculares de Enfermedades Hormonales, Neurodegenerativas y Oncológicas, Department of Biochemistry, School of Medicine, University of Buenos Aires, Paraguay 2155 5th, Buenos Aires, Argentina.
Gadaleta
Mariana
M
Castillo
Ana Fernanda
AF
Duarte
Alejandra
A
Neuman
Isabel
I
Paz
Cristina
C
Cornejo Maciel
Fabiana
F
Podestá
Ernesto J
EJ
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002999:Clone Cells; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D007984:Leydig Cell Tumor / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D007985:Leydig Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D016718:Arachidonic Acid; D004815:Epidermal Growth Factor; D013869:Thiolester Hydrolases; D003066:Coenzyme A Ligases