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Dive into the research topics where Fabiana Cornejo Maciel is active.

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Featured researches published by Fabiana Cornejo Maciel.


PLOS ONE | 2008

A mitochondrial kinase complex is essential to mediate an ERK1/2-dependent phosphorylation of a key regulatory protein in steroid biosynthesis.

Cecilia Poderoso; Daniela P. Converso; Paula Maloberti; Alejandra Duarte; Isabel Neuman; Soledad Galli; Fabiana Cornejo Maciel; Maria Cecilia Carreras; Juan José Poderoso; Ernesto J. Podestá

ERK1/2 is known to be involved in hormone-stimulated steroid synthesis, but its exact roles and the underlying mechanisms remain elusive. Both ERK1/2 phosphorylation and steroidogenesis may be triggered by cAMP/cAMP-dependent protein kinase (PKA)-dependent and-independent mechanisms; however, ERK1/2 activation by cAMP results in a maximal steroidogenic rate, whereas canonical activation by epidermal growth factor (EGF) does not. We demonstrate herein by Western blot analysis and confocal studies that temporal mitochondrial ERK1/2 activation is obligatory for PKA-mediated steroidogenesis in the Leydig-transformed MA-10 cell line. PKA activity leads to the phosphorylation of a constitutive mitochondrial MEK1/2 pool with a lower effect in cytosolic MEKs, while EGF allows predominant cytosolic MEK activation and nuclear pERK1/2 localization. These results would explain why PKA favors a more durable ERK1/2 activation in mitochondria than does EGF. By means of ex vivo experiments, we showed that mitochondrial maximal steroidogenesis occurred as a result of the mutual action of steroidogenic acute regulatory (StAR) protein –a key regulatory component in steroid biosynthesis-, active ERK1/2 and PKA. Our results indicate that there is an interaction between mitochondrial StAR and ERK1/2, involving a D domain with sequential basic-hydrophobic motifs similar to ERK substrates. As a result of this binding and only in the presence of cholesterol, ERK1/2 phosphorylates StAR at Ser232. Directed mutagenesis of Ser232 to a non-phosphorylable amino acid such as Ala (StAR S232A) inhibited in vitro StAR phosphorylation by active ERK1/2. Transient transfection of MA-10 cells with StAR S232A markedly reduced the yield of progesterone production. In summary, here we show that StAR is a novel substrate of ERK1/2, and that mitochondrial ERK1/2 is part of a multimeric protein kinase complex that regulates cholesterol transport. The role of MAPKs in mitochondrial function is underlined.


FEBS Journal | 2005

Silencing the expression of mitochondrial acyl-CoA thioesterase I and acyl-CoA synthetase 4 inhibits hormone-induced steroidogenesis

Paula Maloberti; Rocío Castilla; Fernanda Castillo; Fabiana Cornejo Maciel; Carlos F. Mendez; Ernesto J. Podestá

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 steroid output of cAMP‐stimulated Leydig cells. This effect was blunted by a permeable analog of cholesterol that bypasses the rate‐limiting step in steroidogenesis, the transport of cholesterol from the outer to the inner mitochondrial membrane. The inhibition of steroidogenesis was overcome by addition of exogenous arachidonic acid, indicating that the enzymes are part of the mechanism responsible for arachidonic acid release involved in steroidogenesis. Knocking down the expression of MTE‐I leads to a significant reduction in the expression of steroidogenic acute regulatory protein. This protein is induced by arachidonic acid and controls the rate‐limiting step. Overexpression of MTE‐I resulted in an increase in cAMP‐induced steroidogenesis. In summary, our results demonstrate a critical role for ACS4 and MTE‐I in the hormonal regulation of steroidogenesis as a new pathway of arachidonic acid release different from the classical phospholipase A2 cascade.


PLOS ONE | 2012

Mitochondrial Fusion Is Essential for Steroid Biosynthesis

Alejandra Duarte; Cecilia Poderoso; Mariana Cooke; Gastón Soria; Fabiana Cornejo Maciel; Vanesa Gottifredi; Ernesto J. Podestá

Although the contribution of mitochondrial dynamics (a balance in fusion/fission events and changes in mitochondria subcellular distribution) to key biological process has been reported, the contribution of changes in mitochondrial fusion to achieve efficient steroid production has never been explored. The mitochondria are central during steroid synthesis and different enzymes are localized between the mitochondria and the endoplasmic reticulum to produce the final steroid hormone, thus suggesting that mitochondrial fusion might be relevant for this process. In the present study, we showed that the hormonal stimulation triggers mitochondrial fusion into tubular-shaped structures and we demonstrated that mitochondrial fusion does not only correlate-with but also is an essential step of steroid production, being both events depend on PKA activity. We also demonstrated that the hormone-stimulated relocalization of ERK1/2 in the mitochondrion, a critical step during steroidogenesis, depends on mitochondrial fusion. Additionally, we showed that the SHP2 phosphatase, which is required for full steroidogenesis, simultaneously modulates mitochondrial fusion and ERK1/2 localization in the mitochondrion. Strikingly, we found that mitofusin 2 (Mfn2) expression, a central protein for mitochondrial fusion, is upregulated immediately after hormone stimulation. Moreover, Mfn2 knockdown is sufficient to impair steroid biosynthesis. Together, our findings unveil an essential role for mitochondrial fusion during steroidogenesis. These discoveries highlight the importance of organelles’ reorganization in specialized cells, prompting the exploration of the impact that organelle dynamics has on biological processes that include, but are not limited to, steroid synthesis.


Molecular and Cellular Endocrinology | 2009

Hormonal activation of a kinase cascade localized at the mitochondria is required for StAR protein activity

Cecilia Poderoso; Paula Maloberti; Alejandra Duarte; Isabel Neuman; Fabiana Cornejo Maciel; Ernesto J. Podestá

It is known that ERK1/2 and MEK1/2 participate in the regulation of Star gene transcription. However, their role in StAR protein post-transcriptional regulation is not described yet. In this study we analyzed the relationship between the MAPK cascade and StAR protein phosphorylation and function. We have demonstrated that (a) steroidogenesis in MA-10 Leydig cells depends on the specific of ERK1/2 activation at the mitochondria; (b) ERK1/2 phosphorylation is driven by mitochondrial PKA and constitutive MEK1/2 in this organelle; (c) active ERK1/2 interacts with StAR protein, leads to StAR protein phosphorylation at Ser(232) only in the presence of cholesterol; (d) directed mutagenesis of Ser(232) (S232A) inhibited in vitro StAR protein phosphorylation by ERK1; (e) transient transfection of MA-10 cells with StAR S232A cDNA markedly reduced the yield of progesterone production. We show that StAR protein is a substrate of ERK1/2, and that mitochondrial ERK1/2 is part of a multimeric complex that regulates cholesterol transport.


Endocrine Research | 1997

Involvement of arachidonic acid and the lipoxygenase pathway in mediating luteinizing hormone-induced testosterone synthesis in rat leydig cells

Pablo G. Mele; Laura A. Dada; Isabel Neuman; Cora Cymeryng; Carlos F. Mendez; Carla V. Finkielstein; Fabiana Cornejo Maciel; Ernesto J. Podestá

Evidence has been introduced linking the lipoxygenase products and steroidogenesis in Leydig cells, thereby supporting that this pathway may be a common event in the hormonal control of steroid synthesis. On the other hand, it has also been reported that lipoxygenase products of arachidonic acid (AA) may not be involved in Leydig cells steroidogenesis. In this paper, we investigated the effects of PLA2 and lipoxygenase pathway inhibitors on steroidogenesis in rat testis Leydig cells. The effects of two structurally unrelated PLA2 inhibitors (4-bromophenacyl bromide (BPB) and quinacrine) were determined. BPB blocked the LH- and Bt2cAMP-stimulated testosterone production but had no effect on 22(4)-OH-cholesterol conversion to testosterone. Quinacrine caused a dose-dependent inhibition of LH- and Bt2cAMP-induced steroidogenesis. The effects of different lipoxygenase pathway inhibitors (nordihydroguaiaretic acid (NDGA), 5,8,11,14-eicosatetraynoic acid (ETYA), caffeic acid and esculetin) have also been determined. Both NDGA and ETYA inhibited LH- and Bt2cAMP-stimulated steroid synthesis in a dose-related manner. Furthermore caffeic acid and esculetin also blocked the LH-stimulated testosterone production. Moreover, exogenous AA induced a dose-dependent increase of testosterone secretion which was inhibited by NDGA. Our results strongly support the previous concept that the lipoxygenase pathway is involved in the mechanism of action of LH on testis Leydig cells.


FEBS Journal | 2006

cAMP increases mitochondrial cholesterol transport through the induction of arachidonic acid release inside this organelle in Leydig cells

Ana Fernanda Castillo; Fabiana Cornejo Maciel; Rocío Castilla; Alejandra Duarte; Paula Maloberti; Ernesto J. Podestá

We have investigated the direct effect of arachidonic acid on cholesterol transport in intact cells or isolated mitochondria from steroidogenic cells and the effect of cyclic‐AMP on the specific release of this fatty acid inside the mitochondria. We show for the first time that cyclic‐AMP can regulate the release of arachidonic acid in a specialized compartment of MA‐10 Leydig cells, e.g. the mitochondria, and that the fatty acid induces cholesterol transport through a mechanism different from the classical pathway. Arachidonic acid and arachidonoyl‐CoA can stimulate cholesterol transport in isolated mitochondria from nonstimulated cells. The effect of arachidonoyl‐CoA is inhibited by the reduction in the expression or in the activity of a mitochondrial thioesterase that uses arachidonoyl‐CoA as a substrate to release arachidonic acid. cAMP‐induced arachidonic acid accumulation into the mitochondria is also reduced when the mitochondrial thioesterase activity or expression is blocked. This new feature in the regulation of cholesterol transport by arachidonic acid and the release of arachidonic acid in specialized compartment of the cells could offer novel means for understanding the regulation of steroid synthesis but also would be important in other situations such as neuropathological disorders or oncology disorders, where cholesterol transport plays an important role.


FEBS Letters | 2007

An arachidonic acid generation/export system involved in the regulation of cholesterol transport in mitochondria of steroidogenic cells

Alejandra Duarte; Ana Fernanda Castillo; Rocío Castilla; Paula Maloberti; Ernesto J. Podestá; Fabiana Cornejo Maciel

Recent studies demonstrated the importance of the mitochondrial ATP in the regulation of a novel long‐chain fatty acid generation/export system in mitochondria of diabetic rat heart. In steroidogenic systems, mitochondrial ATP and intramitochondrial arachidonic acid (AA) generation are important for steroidogenesis. Here, we report that mitochondrial ATP is necessary for the generation and export of AA, steroid production and steroidogenic acute regulatory protein induction supported by cyclic 3′–5′‐adenosine monophosphate in steroidogenic cells. These results demonstrate that ATP depletion affects AA export and provide new evidence of the existence of the fatty acid generation and export system involved in mitochondrial cholesterol transport.


Journal of Lipid Research | 2011

Tyrosine phosphatase SHP2 regulates the expression of acyl-CoA synthetase ACSL4

Mariana Cooke; Ulises Orlando; Paula Maloberti; Ernesto J. Podestá; Fabiana Cornejo Maciel

Acyl-CoA synthetase 4 (ACSL4) is implicated in fatty acid metabolism with marked preference for arachidonic acid (AA). ACSL4 plays crucial roles in physiological functions such as steroid synthesis and in pathological processes such as tumorigenesis. However, factors regulating ACSL4 mRNA and/or protein levels are not fully described. Because ACSL4 protein expression requires tyrosine phosphatase activity, in this study we aimed to identify the tyrosine phosphatase involved in ACSL4 expression. NSC87877, a specific inhibitor of the tyrosine phosphatase SHP2, reduced ACSL4 protein levels in ACSL4-rich breast cancer cells and steroidogenic cells. Indeed, overexpression of an active form of SHP2 increased ACSL4 protein levels in MA-10 Leydig steroidogenic cells. SHP2 has to be activated through a cAMP-dependent pathway to exert its effect on ACSL4. The effects could be specifically attributed to SHP2 because knockdown of the phosphatase reduced ACSL4 mRNA and protein levels. Through the action on ACSL4 protein levels, SHP2 affected AA-CoA production and metabolism and, finally, the steroidogenic capacity of MA-10 cells: overexpression (or knockdown) of SHP2 led to increased (or decreased) steroid production. We describe for the first time the involvement of SHP2 activity in the regulation of the expression of the fatty acid-metabolizing enzyme ACSL4.


The Journal of Steroid Biochemistry and Molecular Biology | 2006

Protein tyrosine phosphatases regulate arachidonic acid release, StAR induction and steroidogenesis acting on a hormone-dependent arachidonic acid-preferring acyl-CoA synthetase.

Florencia Cano; Cecilia Poderoso; Fabiana Cornejo Maciel; Rocío Castilla; Paula Maloberti; Fernanda Castillo; Isabel Neuman; Ernesto J. Podestá

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) mediated by two enzymes, ACS4 (acyl-CoA synthetase 4) and Acot2 (mitochondrial thioesterase). ACTH and LH regulate the activity of PTPs and Acot2 and promote the induction of ACS4. Here we analyzed the involvement of PTPs on the expression of ACS4. We found that two PTP inhibitors, acting through different mechanisms, are both able to abrogate the hormonal effect on ACS4 induction. PTP inhibitors also reduce the effect of cAMP on steroidogenesis and on the level of StAR protein, which facilitates the access of cholesterol into the mitochondria. Moreover, our results indicate that exogenous AA is able to overcome the inhibition produced by PTP inhibitors on StAR protein level and steroidogenesis. Then, here we describe a link between PTP activity and AA release, since ACS4 induction is under the control of PTP activity, being a key event for AA release, StAR induction and steroidogenesis.


Endocrine Research | 2000

An Acth-Activated Protein Tyrosine Phosphatase (PTP) is Modulated by Pka-Mediated Phosphorylation

Fabiana Cornejo Maciel; Cecilia Poderoso; Alejandra Gorostizaga; Ernesto J. Podestá

In adrenal cortex, ACTH regulation of steroidogenesis depends on PKA-dependent serine/threonine phosphorylation and also on the activity of protein tyrosine phosphatases (PTPs). In addition, ACTH increases total PTPs involving at least three soluble PTPs (50, 82 and 115 kDa). Serine/threonine phosphorylation of these enzymes themselves could be a regulatory mechanism of their activity since the increase of total PTP activity is dependent on PKA-activation. In this report we analyzed the effect of in vitro phospho-dephosphorylation processes on the activity displayed by the ACTH-activated PTP of 115 kDa. Using an in-gel PTP assay we demonstrate that dephosphorylation catalyzed by potato acid phosphatase (PAP) reduces the activity of the 115 kDa PTP present in ZF from ACTH-treated animals and PKA-mediated phosphorylation reverses this effect.

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Dive into the Fabiana Cornejo Maciel's collaboration.

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Paula Maloberti

University of Buenos Aires

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Cecilia Poderoso

University of Buenos Aires

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Isabel Neuman

University of Buenos Aires

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Alejandra Duarte

University of Buenos Aires

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Carlos F. Mendez

University of Buenos Aires

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Pablo G. Mele

University of Buenos Aires

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Rocío Castilla

University of Buenos Aires

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Mariana Cooke

University of Buenos Aires

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