EGF releases arachidonic acid (AA) through ACS4 and Acot2 action in steroidogenic cells

CASTILLA ROCÍO; GADALETA MARIANA; DUARTE ALEJANDRA; PODESTÁ ERNESTO J

Rosario, Santa Fé, Argentina

Congreso; XLII Reunión Anual / 2006, 42th Annual Meeting. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).

AA plays a pivotal role in cell signaling and proliferation and its release has been shown in response to EGF and other growth stimuli. AA is also the precursor for several eicosanoids with potent effects on inflammation and cell growth. In Steroidogenic cells EGF promotes an increase in the steroidogenesis and releases AA although the proteins involved in this event are unknown. We previously have shown that steroidogenic hormones release AA for steroids synthesis by a concerted action of an acyl-CoA synthetase (ACS4) and a mitochondrial Acyl-CoA thioesterase (Acot2).The aim of this study was to determine whether EGF produces AA release through ACS4 and Acot2 actions. For this purpose, MA-10 Leydig cells or Y1 adrenal cells were incubated in presence of EGF and ACS4 and Acot2 expressions were analyzed by Western-blot. We determined a doses dependent increment of both enzymes with a maximal expression at 10 nM EGF. We studied the temporal response pattern of ACS4 and Acot2 expressions, which reached their maximum at 30 min and then gradually decreased. The intramitochondrial AA release was studied by TLC using [14C]-AA. EGF stimulated the AA mitochondrial content 29%± 3. These results show the EGF induction of both ACS4 and Acot 2 for the first time and the participation of these enzymes in the EGF-AA release, which, in turn, regulates the steroidogenesis and cell proliferation.