Laura Brion

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RATIONALE In human genetic studies a single nucleotide polymorphism within the salt-inducible kinase 1 (SIK1) gene was associated with hypertension. Lower SIK1 activity in vascular smooth muscle cells (VSMCs) leads to decreased sodium-potassium ATPase activity, which associates with increased vascular tone. Also, SIK1 participates in a negative feedback(More)
Testicular function is highly dependent on temperature control. In Leydig testicular cells, the signaling pathway activated by heat stress is poorly defined. Here we describe the molecular events triggered by heat shock (HS, 10 min, 45 degrees C) in MA-10 cells. HS produced a rapid and transient activation of ERK1/2 and JNK kinases, and also increased MAP(More)
Several stimuli, including stress conditions, promote the activation of MAP kinases family members (ERK1/2, JNK, p38). In turn, these enzymes regulate several cellular functions. Given that MAPK activation requires the phosphorylation of these proteins, their inactivation depends on the activity of specific phosphatases. MAPK phosphatase-1 (MKP-1), a(More)
MAP kinases (MAPKs), such as ERK1/2, exert profound effects on a variety of physiological processes. In steroidogenic cells, ERK1/2 are involved in the expression and activation of steroidogenic acute regulatory protein, which plays a central role in the regulation of steroidogenesis. In MA-10 Leydig cells, LH and chorionic gonadotropin (CG) trigger(More)
The protein kinase liver kinase B1 (LKB1) regulates cell polarity and intercellular junction stability. Also, LKB1 controls the activity of salt-inducible kinase 1 (SIK1). The role and relevance of SIK1 and its downstream effectors in linking the LKB1 signals within these processes are partially understood. We hypothesize that SIK1 may link LKB1 signals to(More)
Several reports suggest putative interactions between valproic acid (VPA) treatment and the hypothalamus-pituitary-adrenal axis. Given that VPA alters mitochondrial functions, an action of this drug on a mitochondrial process such as steroid synthesis in adrenal cells should be expected. In order to disclose a putative action of VPA on the adrenocortical(More)
In adrenocortical and Leydig cells PKA activation by trophic hormones increases the activity of protein tyrosine phosphatases and also induces the expression of MAP kinase phosphatase 1 (MKP-1), a dual activity protein phosphatase (serine/threonine and tyrosine). This work summarizes the knowledge on the regulation and the role played by cAMP-activated(More)
MAPKs such as ERK1/2 are dephosphorylated, and consequently inactivated, by dual specificity phosphatases (MKPs). In Leydig cells, LH triggers ERK1/2 phosphorylation through the action of protein kinase A. We demonstrate that, in MA-10 Leydig cells, LH receptor activation by human chorionic gonadotropin (hCG) up-regulates MKP-2, a phosphatase that(More)
In Leydig cells, LH and cAMP promote ERK1/2 activation and MAPK phosphatase-1 (MKP-1) induction. MKP-1 up-regulation, which involves post-translational modifications such as ERK1/2-mediated phosphorylation, reduces ERK1/2 phosphorylation as well as Steroidogenic Acute Regulatory (StAR) protein expression and steroidogenesis. As LH- and cAMP-promoted StAR(More)
Deep abdominal palpation was performed prospectively in 900 newborns. Normal kidneys were felt in all but 8. 2 of these had a normal ultrasonography, 2 had an obstructive hydronephrosis, 1 had bilateral renal hypoplasia and 3 had a previously undiagnosed unilateral renal agenesis. Despite the increasing use of prenatal ultrasonography, careful abdominal(More)