Fernanda Castillo

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The activation of the rate-limiting step in steroid biosynthesis, that is the transport of cholesterol into the mitochondria, is dependent on PKA-mediated events triggered by hormones like ACTH and LH. Two of such events are the protein tyrosine dephosphorylation mediated by protein tyrosine phosphatases (PTPs) and the release of arachidonic acid (AA)(More)
Arachidonic acid and its lypoxygenated metabolites play a fundamental role in the hormonal regulation of steroidogenesis. Reduction in the expression of the mitochondrial acyl-CoA thioesterase (MTE-I) by antisense or small interfering RNA (siRNA) and of the arachidonic acid-preferring acyl-CoA synthetase (ACS4) by siRNA produced a marked reduction in(More)
Although the role of arachidonic acid (AA) in trophic hormone-stimulated steroid production in various steroidogenic cells is well documented, the mechanism responsible for AA release remains unknown. We have previously shown evidence of an alternative pathway of AA generation in steroidogenic tissues. Our results are consistent with the hypothesis that, in(More)
We have described that, in adrenal and Leydig cells, the hormonal regulation of free arachidonic acid (AA) concentration is mediated by the concerted action of two enzymes: an acyl-CoA thioesterase (MTE-I or ARTISt) and an acyl-CoA synthetase (ACS4). In this study we analyzed the potential regulation of these proteins by hormonal action in steroidogenic(More)
The ACTH signaling pathway includes both PKA activation as well as PKA-dependent tyrosine phosphatase activation. In addition, the action of this hormone also includes the regulation of the intracellular levels of arachidonic acid (AA) by the concerted action of two enzymes: an acylCoA-thioesterase and an acyl-CoA-synthetase (ACS4). This work describes the(More)
Purified membranes were prepared from seven human T-mycoplasmas of which four are laboratory strains and three isolates from patients with nonspecific urethritis. The T-mycoplasmas were resistant to osmotic shock and sonication. Membranes were obtained only after lysing most of the T-mycoplasmas by four passes through a cell fractionator at 40,000 psi and(More)
Bacterial Nitrogenase, Nitrite Inhibition, Dinitrogenase Reductase Dinitrogen fixation by crude extracts from Rhodopseudomonas palustris and Rhodomicrobium vannielii and by purified nitrogenase preparations from Azotobacter vinelandii and Clostridium pasteurianum is inhibited by nitrite, whereas in the same preparations nitrate is without effect. In(More)
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