Renoprotective effects of atorvastatin in diabetic mice: downregulation of RhoA and upregulation of Akt/GSK3

Potential benefits of statins in the treatment of chronic kidney disease beyond lipid-lowering effects have been described. However, molecular mechanisms involved in renoprotective actions of statins have not been fully elucidated. We questioned whether statins influence development of diabetic nephropathy through reactive oxygen species, RhoA and Akt/GSK3 pathway, known to be important in renal pathology. Diabetic mice (db/db) and their control counterparts (db/+) were treated with atorvastatin (10 mg/Kg/day, p.o., for 2 weeks). Diabetes-associated renal injury was characterized by albuminuria (albumin:creatinine ratio, db/+: 3.2 ± 0.6 vs. db/db: 12.5 ± 3.1*; *P<0.05), increased glomerular/mesangial surface area, and kidney hypertrophy. Renal injury was attenuated in atorvastatin-treated db/db mice. Increased ROS generation in the renal cortex of db/db mice was also inhibited by atorvastatin. ERK1/2 phosphorylation was increased in the renal cortex of db/db mice. Increased renal expression of Nox4 and proliferating cell nuclear antigen, observed in db/db mice, were abrogated by statin treatment. Atorvastatin also upregulated Akt/GSK3β phosphorylation in the renal cortex of db/db mice. Our findings suggest that atorvastatin attenuates diabetes-associated renal injury by reducing ROS generation, RhoA activity and normalizing Akt/GSK3β signaling pathways. The present study provides some new insights into molecular mechanisms whereby statins may protect against renal injury in diabetes

Impaired calcium influx despite hyper-reactivity in contralateral carotid following balloon injury: eNOS involvement

Balloon catheter injury results in hyper-reactivity to phenylephrine in contralateral carotids. Decreased nitric oxide (NO) modulation and/or increased intracellular calcium concentration triggers vascular smooth muscle contraction. Therefore, this study explores the participation of NO signaling pathway and calcium mobilization on hyper-reactivity to phenylephrine in contralateral carotids. Concentration-response curves for calcium (CaCl(2)) and phenylephrine were obtained in control and contralateral carotids four days after balloon injury, in the presence and absence of the inhibitors (L-NAME, L-NNA, 1400W, 7-NI, Oxyhemoglobin, ODQ or Tiron). Confocal microscopy using Fluo-3AM or DHE was performed to detect the intracellular levels of calcium and reactive oxygen species, respectively. The modulation of NO on phenylephrine-induced contraction was absent in the contralateral carotid. Phenylephrine-induced intracellular calcium mobilization was not altered in contralateral carotids. However, extracellular calcium mobilization by phenylephrine was reduced in the contralateral carotid compared to control arteries, and this result was confirmed by confocal microscopy. L-NAME increased phenylephrine-induced extracellular calcium mobilization in the contralateral carotid to the control levels. Results obtained with L-NNA, 1400W, 7-NI, OxyHb, ODQ or Tiron showed that this response was mediated by products from endothelial NOS (eNOS) different from NO and without soluble guanylate cyclase activation, but it involved superoxide anions. Furthermore. Tiron or L-NNA reduced the levels of reactive oxygen species in contralateral carotids. Data suggest that balloon catheter injury promoted eNOS uncoupling in contralateral carotids, which generates superoxide rather than NO, and reduces phenylephrine-induced extracellular calcium mobilization, despite the hyper-reactivity to phenylephrine in contralateral carotids. (C) 2010 Elsevier B.V. All rights reserved

Searching for original natural products by molecular networking: detection, isolation and total synthesis of chloroaustralasines

International audiencea With the aim of isolating structurally original natural products, a molecular networking (MN)-based priori-tisation approach has been developed and applied to a collection of 292 plant extracts. It led to the selection of a sample-specific cluster of ions detected in the bark extract of Codiaeum peltatum. The MN-guided purification of the targeted compounds afforded four unprecedented chlorinated monoterpenyl quinolones named chloroaustralasines A-C and isochloroaustralasine A. Faced with inconsistent spectral data of some previously reported quinolones, the total synthesis of the corresponding dihydroxy and chlorohydrin compounds was undertaken. The desired products were obtained in three steps, allowing the structural reassignment of two erioaustralasines. The chloroperoxidase-mediated hydroxychlorination reaction developed for the synthesis of the chlorinated quinolone showed that such complex molecules could be good substrates for this enzyme and, at the same time, raised the question of the biosynthetic origin of the non-artefactual chlorohydrin moiety

Bioactive Natural Products Prioritization Using Massive Multi-informational Molecular Networks.

Natural products represent an inexhaustible source of novel therapeutic agents. Their complex and constrained three-dimensional structures endow these molecules with exceptional biological properties, thereby giving them a major role in drug discovery programs. However, the search for new bioactive metabolites is hampered by the chemical complexity of the biological matrices in which they are found. The purification of single constituents from such matrices requires such a significant amount of work that it should be ideally performed only on molecules of high potential value (i.e., chemical novelty and biological activity). Recent bioinformatics approaches based on mass spectrometry metabolite profiling methods are beginning to address the complex task of compound identification within complex mixtures. However, in parallel to these developments, methods providing information on the bioactivity potential of natural products prior to their isolation are still lacking and are of key interest to target the isolation of valuable natural products only. In the present investigation, we propose an integrated analysis strategy for bioactive natural products prioritization. Our approach uses massive molecular networks embedding various informational layers (bioactivity and taxonomical data) to highlight potentially bioactive scaffolds within the chemical diversity of crude extracts collections. We exemplify this workflow by targeting the isolation of predicted active and nonactive metabolites from two botanical sources (Bocquillonia nervosa and Neoguillauminia cleopatra) against two biological targets (Wnt signaling pathway and chikungunya virus replication). Eventually, the detection and isolation processes of a daphnane diterpene orthoester and four 12-deoxyphorbols inhibiting the Wnt signaling pathway and exhibiting potent antiviral activities against the CHIKV virus are detailed. Combined with efficient metabolite annotation tools, this bioactive natural products prioritization pipeline proves to be efficient. Implementation of this approach in drug discovery programs based on natural extract screening should speed up and rationalize the isolation of bioactive natural products

Atorvastatin reduces RhoA translocation from cytosol to the membane in kidneys of diabetic mice.

<p>RhoA translocation (A) and RhoA immunolocalization (B) from renal cortex obtained from db/+ and db/db mice treated with atorvastatin (10 mg/kg/day for 2 weeks) or control diet. Translocation of RhoA was assessed by protein expression in the membrane and cytosolic fractions isolated from renal cortex homogenates. Results are mean ± SEM of 3–6 mice in each experimental group. *P< 0.05 vs. db/+ control diet, **P<0.05 db/db atorvastatin diet vs. db/db control diet.</p

Increased renal ERK1/2 MAPK phosphorylation is abrogated by atorvastatin in db/db mice.

<p>Phosphorylation levels of SAPK/JNK MAPK (A), p38 MAPK (B), and ERK1/2 MAPK (C) were evaluated in renal cortex isolated from db/+ and db/db mice treated with atorvastatin (10 mg/kg/day for 2 weeks) or control diet. Top panels, representative immunoblots of SAPK/JNK MAPK [Thr¹⁸³/Tyr¹⁸⁵], p38 MAPK [Thr¹⁸⁰/Tyr¹⁸²], ERK1/2 MAPK [Thr²⁰²/Tyr²⁰⁴] and β-actin. Results are presented as mean ± SEM of 6–8 mice in each experimental group. *P< 0.05 vs. db/+ control diet, **P<0.05 db/db atorvastatin diet vs. db/db control diet.</p