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See detailDiscovery and pharmacological characterization of succinate receptor (SUCNR1/GPR91) agonists
Geubelle, Pierre ULg; Gilissen, Julie; Dilly, Sebastien et al

in British Journal of Pharmacology (in press)

Background and Purpose The succinate receptor (SUCNR1 or GPR91) has been described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho ... [more ▼]

Background and Purpose The succinate receptor (SUCNR1 or GPR91) has been described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho)physiological processes, the function of SUCNR1 has remained elusive because no pharmacological tools were available. We report on the discovery of the first family of synthetic potent agonists. Experimental Approach We screened a library of succinate analogues and analysed their activity on SUCNR1. In addition, we modelled a pharmacophore and a binding site for the receptor. New agonists were identified based on the information provided by these two approaches. Their activity was studied in various bioassays, including measurement of cAMP levels, [Ca2+]i mobilisation, TGF-α shedding and recruitment of arrestin 3. The in vivo impact of SUCNR1 activation by these new agonists was evaluated on rat blood pressure. Key Results We identified cis-epoxysuccinic acid and cis-1,2-cyclopropanedicarboxylic acid as agonists with an efficacy similar to the one of succinic acid. Interestingly, cis-epoxysuccinic acid was characterized by a 10 to 20 fold higher potency than succinate on the receptor. For example, cis-epoxysuccinic acid reduced cAMP levels with a pEC50 = 5.57 ± 0.02 (EC50 = 2.7 μM) as compared to succinate pEC50 = 4.54 ± 0.08 (EC50 = 29 μM). The rank order of potency of the three agonists was the same in all bioassays tested. In vivo, cis-epoxysuccinic and cis-1,2-cyclopropanedicarboxylic acid increased rat blood pressure to the same extent as succinate did. Conclusions and Implications We provide new agonist tools for SUCNR1 that should facilitate further research on this understudied receptor. [less ▲]

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See detailintravenous administration of mesenchymal stream cells modulates renal lipid metabolism in rats
ERPICUM, Pauline ULg; Rowart, Pascal ULg; POMA, Laurence ULg et al

Conference (2017, March 16)

Mesenchymal stromal cells (MSC) have been shown to attenuate renal ischemia/reperfusion (I/R) injury in rodents. Still, the mechanisms of such a nephroprotection remain unclear. Here, rats were ... [more ▼]

Mesenchymal stromal cells (MSC) have been shown to attenuate renal ischemia/reperfusion (I/R) injury in rodents. Still, the mechanisms of such a nephroprotection remain unclear. Here, rats were intravenously infused with MSC (1.5x10^6 cells in 1 ml saline; MSCD-7 group, n=6) or equivalent volume of saline (SD-7 group, n=6) 7 days before kidney sampling. High-throughput RNA sequencing technology was used to compare transcriptomic renal profiles, using TopHat and Cufflinks open-source software tools. A total of 494 and 256 genes were found to be significantly (q-value <.05) down- and up-regulated in mscd-7 versus sd-7 groups, respectively. Hierarchical cluster analysis by “david” “webgestalt” softwares highlighted that the metabolic pathways mostly affected msc included adipogenesis, insulin signalling, fatty acid (fa) biosynthesis, il-6 b-cell receptor il-3 pathway nuclear receptors involved lipid me- tabolism. Real-time qpcr immunoblotting analyses confirmed pivotal enzymes of fa biosynthesis were significantly downregulated group, whereas expression ppar alpha, a transcription factor oxidation, was induced msc. Additional- ly, fat />CD36 – a key regulator of membrane uptake of FA – was increased in MSCD-7 kidneys, with a preferential localization in proximal tubules (PT). As a whole, our data suggest that MSC infusion causes critical modifications of lipid metabolism, including (i) down-regulation of FA biosynthesis; (ii) activation of PPAR alpha pathway, and (iii) prioritization of FA as sources of energy in PT cells, which may eventually prevent lipid peroxidation and attenuate renal I/R damage. [less ▲]

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See detailImpact of timing administration of mesenchymal stromal cells on serum creatinine following renal ischemia/ reperfusion in rats
ERPICUM, Pauline ULg; Rowart, Pascal ULg; POMA, Laurence ULg et al

in Transplant International (2015, November), 28(S4), 1129

Experimental models of renal ischemia/reperfusion (I/R) have suggested protective effects of mesenchymal stromal cells (MSC) therapy. Still, param- eters of MSC injection, including volume, route and ... [more ▼]

Experimental models of renal ischemia/reperfusion (I/R) have suggested protective effects of mesenchymal stromal cells (MSC) therapy. Still, param- eters of MSC injection, including volume, route and timing of cell administration, remain largely debated. Particularly, MSC infusion in mouse has been shown to be beneficial “a priori” but deleterious “a posteriori” of renal I/R injury. In order to further investigate the influence of the timing of MSC administration, we used 10-week-old Lewis rats categorized in 4 groups. Groups 1 (MSC D-7, n = 10) and 2 (MSC D + 1, n = 7) received caudal i.v. injection of MSC (1.5 9 106 in 1 ml of saline) 7 days before or 1 day after renal I/R, respectively. Control groups 3 (saline D-7, n = 6) and 4 (saline D + 1, n = 6) received equal volume of saline at similar time points. Left renal ischemia (by clamping of the renal pedicle) lasted 45 min. Right nephrectomy was simultaneously performed. Blood sample was collected from inferior vena cava at 48 h post reperfusion. MSC phenotype was confirmed by FACS analysis. In groups 1 and 3, serum creatinine (SCr) reached 1.4 ` 0.7 versus 2.4 ` 0.8 mg/dl, respectively (p < 0.05). In groups 2 and 4, SCr was 4.9 ` 0.7 versus 3.3 ` 0.9 mg/dl, respectively (p < 0.001). Furthermore, SCr levels were statistically worse when MSC were administered after renal I/R in comparison to a priori infusion (p < 0.0001). In conclusion, MSC administration 7 days prior to renal I/R attenuates kidney injury in comparison to (i) saline infusion or (ii) MSC infusion 1 day after renal I/R. Conversely, on the basis of SCr levels, MSC therapy performed after renal I/R worsens kidney injury in rats. [less ▲]

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See detailActivation of the calcium-sensing receptor before renal ischemia/reperfusion exacerbates kidney injury
WEEKERS, Laurent ULg; De Tullio, Pascal ULg; BOVY, Christophe ULg et al

in American Journal of Translational Research (2015), 7(1), 128-138

Activation of the calcium-sensing receptor (CaSR) by ischemia/reperfusion (I/R) favours apoptosis in cardiomyocytes, hepatocytes and neurons. Its role in renal I/R is unknown. We investigated the impact ... [more ▼]

Activation of the calcium-sensing receptor (CaSR) by ischemia/reperfusion (I/R) favours apoptosis in cardiomyocytes, hepatocytes and neurons. Its role in renal I/R is unknown. We investigated the impact of pharmacological preactivation of the CaSR on kidney structure and function in a murine model of bilateral renal 30-min ischemia and 48-hour reperfusion, and in a 6-year cohort of kidney transplant recipients (KTR). C57BL/6J mice were administered daily with CaSR agonist, R-568, or with vehicle for 48 hours. Evaluation of serum urea and creatinine levels, renal histology and urine metabolome by nuclear magnetic resonance showed that R-568 was not nephrotoxic per se. Following I/R, serum urea and creatinine levels increased higher in R-568-treated animals than in controls. Jablonski’s score was significantly greater in R-568-treated kidneys, which showed a higher rate of cell proliferation and apoptosis in comparison to controls. Next, we retrospectively identified 36 patients (10.7% of our cohort) who were treated by CaSR agonist, cinacalcet, at the time of kidney transplantation (KTx). After matching these to 61 KTR upon type of donor, cold ischemic time, residual diuresis, and donor age, we observed that delayed graft function, i.e. need for dialysis in the first week after KTx, occurred in 42 and 23% of cinacalcet-treated and control groups, respectively (p≤0.05). These data suggest that pharmacological preactivation of the CaSR before renal I/R exacerbates kidney injury. [less ▲]

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