BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disorder, which is characterized by raised serum bile acid level and potential adverse fetal outcome. Farnesoid X receptor (FXR), also known as a bile acid receptor, was found to be expressed in placenta with low level. Whether activation of FXR by specific agonists could regulate the pathogenesis of ICP is still unclear.
METHODS: A model of maternal cholestasis was induced by administration of 17α-ethynylestradiol (E2) in pregnant mice for 6 days. We explored the regulatory effect of WAY-362450 (W450), a highly selective and potent FXR agonist on placenta.
RESULTS: In this study, we demonstrated that administration of E2 increased bile acid levels in mouse serum, liver and amniotic fluid. Bile acid levels were significantly decreased after W450 treatment. W450 protected against the impairment of placentas induced by E2, including severe intracellular edema and apoptosis of trophoblasts. Moreover, W450 significantly induced the expressions of FXR target bile acid transport gene ATP-binding cassette, sub-family B (MDR/TAP), member 11 (Abcb11;Bsep) in placenta. W450 could also attenuate placental oxidative stress and increase the expressions of antioxidant enzymes Prdx1 and Prdx3.
CONCLUSIONS: In conclusion, our data demonstrated that FXR agonist W450 modulated bile acid balance and protected against placental oxidative stress. Thus, our results support that potent FXR agonists might represent promising drugs for the treatment of ICP.

BACKGROUND: Dilated cardiomyopathy (DCM) is a public health problem with no available curative treatment, and mitochondrial dysfunction plays a critical role in its development. The present study is the first to analyze the mitochondrial proteome in cardiac tissue of patients with DCM to identify potential molecular targets for its therapeutic intervention.
RESULTS: 16 left ventricular (LV) samples obtained from explanted human hearts with DCM (n = 8) and control donors (n = 8) were extracted to perform a proteomic approach to investigate the variations in mitochondrial protein expression. The proteome of the samples was analyzed by quantitative differential electrophoresis and Mass Spectrometry. These changes were validated by classical techniques and by novel and precise selected reaction monitoring analysis and RNA sequencing approach increasing the total heart samples up to 25. We found significant alterations in energy metabolism, especially in molecules involved in substrate utilization (ODPA, ETFD, DLDH), energy production (ATPA), other metabolic pathways (AL4A1) and protein synthesis (EFTU), obtaining considerable and specific relationships between the alterations detected in these processes. Importantly, we observed that the antioxidant PRDX3 overexpression is associated with impaired ventricular function. PRDX3 is significantly related to LV end systolic and diastolic diameter (r = 0.73, p value<0.01; r = 0.71, p value<0.01), fractional shortening, and ejection fraction (r = -0.61, p value<0.05; and r = -0.62, p value<0.05, respectively).
CONCLUSIONS: This work could be a pivotal study to gain more knowledge on the cellular mechanisms related to the pathophysiology of this disease and may lead to the development of etiology-specific heart failure therapies. We suggest new molecular targets for therapeutic interventions, something that up to now has been lacking.

Hirschsprung\'s disease (HSCR) is a developmental disorder of the enteric nervous system characterized by aganglionosis in distal gut. In this study, we used two-dimensional gel electrophoresis (2-DE) technology coupled with matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis to identify differentially expressed proteins in the aganglionic (stenotic) and ganglionic (normal) colon segment tissues from patients with HSCR. We identified 15 proteins with different expression levels between the stenotic and the normal colon segment tissues from patients with HSCR. Nine proteins were upregulated and six proteins downregulated in the stenotic colon segment tissues compared to the normal colon segment tissues. Based on the biological functions, we selected the Hsp27 upregulated proteins and the PRDX3 downregulated proteins to confirm their expression in 20 patients. The protein and mRNA expressions of Hsp27 were statistically higher in the stenotic colon segment tissues than in the normal colon segment tissues, whereas the protein and mRNA expressions of PRDX3 were statistically lower in the stenotic colon segment tissues than in the normal colon segment tissues. These findings of changes in mRNA and protein in tissues from patients with HSCR provide information which may be helpful in understanding the pathomechanism that is implicated in the disease.

Members of the peroxiredoxin (Prx) family of antioxidant enzymes are inactivated via hyperoxidation of the active site cysteine by the substrate H2O2 and are reactivated via an ATP-consuming process catalyzed by sulfiredoxin (Srx). PrxIII is reversibly inactivated by H2O2 produced by cytochrome P450 11B1 (CYP11B1) in mitochondria during corticosterone synthesis in the adrenal gland of mice injected with adrenocorticotropic hormone (ACTH). Inactivation of PrxIII triggers a sequence of events including accumulation of H2O2, activation of p38 mitogen-activated kinase (MAPK), inhibition of cholesterol transfer, and suppression of corticosterone synthesis. Srx expression is significantly induced by ACTH injection. The coupling of CYP11B1 activity to PrxIII inactivation and Srx induction provides a feedback regulatory mechanism for steroidogenesis that functions independently of the hypothalamic-pituitary-adrenal axis. Furthermore, the PrxIII-Srx regulatory pathway is critical for the circadian rhythm of corticosterone production. Although adrenocortical tumor cell lines such as Y-1 and H295R have been used extensively for studying the mechanism of steroidogenesis, those clonal cells were found to be unsuitable as an in vitro model for redox signaling because the amount of Srx in the cell lines is much higher than that in mouse adrenal gland and not affected by ACTH stimulation. Furthermore, the levels of PrxIII in the clonal cells are greatly reduced compared to that in the adrenal gland, and ACTH does not induce PrxIII hyperoxidation in the clonal cells. Primary adrenocortical cells isolated from the mouse adrenal gland were also found to be an invalid model because Srx levels are increased, along with decreased levels of hyperoxidized PrxIII, soon after isolation of these cells. Organ culture system is, however, appropriate for studying the PrxIII-Srx regulatory function as the levels of hyperoxidized PrxIII and Srx in the adrenal glands maintained overnight in culture medium are not changed.

Peroxiredoxins (Prx) are thiol peroxidases that exhibit exceptionally high reactivity toward peroxides, but the chemical basis for this is not well understood. We present strong experimental evidence that two highly conserved arginine residues play a vital role in this activity of human Prx2 and Prx3. Point mutation of either ArgI or ArgII (in Prx3 Arg-123 and Arg-146, which are ∼3-4 Å or ∼6-7 Å away from the active site peroxidative cysteine (C(p)), respectively) in each case resulted in a 5 orders of magnitude loss in reactivity. A further 2 orders of magnitude decrease in the second-order rate constant was observed for the double arginine mutants of both isoforms, suggesting a cooperative function for these residues. Detailed ab initio theoretical calculations carried out with the high level G4 procedure suggest strong catalytic effects of H-bond-donating functional groups to the C(p) sulfur and the reactive and leaving oxygens of the peroxide in a cooperative manner. Using a guanidinium cation in the calculations to mimic the functional group of arginine, we were able to locate two transition structures that indicate rate enhancements consistent with our experimentally observed rate constants. Our results provide strong evidence for a vital role of ArgI in activating the peroxide that also involves H-bonding to ArgII. This mechanism could explain the exceptional reactivity of peroxiredoxins toward H(2)O(2) and may have wider implications for protein thiol reactivity toward peroxides.