Systems biology analysis reveals role of MDM2 in diabetic nephropathy
Rintaro Saito, … , Hans Joachim Anders, Kumar Sharma
Rintaro Saito, … , Hans Joachim Anders, Kumar Sharma
Published October 20, 2016
Citation Information: JCI Insight. 2016;1(17):e87877. https://doi.org/10.1172/jci.insight.87877.
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Research Article Nephrology

Systems biology analysis reveals role of MDM2 in diabetic nephropathy

Abstract

To derive new insights in diabetic complications, we integrated publicly available human protein-protein interaction (PPI) networks with global metabolic networks using metabolomic data from patients with diabetic nephropathy. We focused on the participating proteins in the network that were computationally predicted to connect the urine metabolites. MDM2 had the highest significant number of PPI connections. As validation, significant downregulation of MDM2 gene expression was found in both glomerular and tubulointerstitial compartments of kidney biopsy tissue from 2 independent cohorts of patients with diabetic nephropathy. In diabetic mice, chemical inhibition of MDM2 with Nutlin-3a led to reduction in the number of podocytes, increased blood urea nitrogen, and increased mortality. Addition of Nutlin-3a decreased WT1+ cells in embryonic kidneys. Both podocyte- and tubule-specific MDM2-knockout mice exhibited severe glomerular and tubular dysfunction, respectively. Interestingly, the only 2 metabolites that were reduced in both podocyte and tubule-specific MDM2-knockout mice were 3-methylcrotonylglycine and uracil, both of which were also reduced in human diabetic kidney disease. Thus, our bioinformatics tool combined with multi-omics studies identified an important functional role for MDM2 in glomeruli and tubules of the diabetic nephropathic kidney and links MDM2 to a reduction in 2 key metabolite biomarkers.

Authors

Rintaro Saito, Anaïs Rocanin-Arjo, Young-Hyun You, Manjula Darshi, Benjamin Van Espen, Satoshi Miyamoto, Jessica Pham, Minya Pu, Simone Romoli, Loki Natarajan, Wenjun Ju, Matthias Kretzler, Robert Nelson, Keiichiro Ono, Dana Thomasova, Shrikant R. Mulay, Trey Ideker, Vivette D’Agati, Ergin Beyret, Juan Carlos Izpisua Belmonte, Hans Joachim Anders, Kumar Sharma

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Figure 5

Pharmacological inhibition of MDM2 in uninephrectomized Leprdb–/– (db/db) mice fed with high-fat diet.

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Pharmacological inhibition of MDM2 in uninephrectomized Leprdb–/– (db/db...
(A) Survival in Nutlin-3a–treated db/db mice (37.5% at the end of the treatment) compared with that of vehicle-treated db/db mice (57%, P = 0.2, log-rank test). (B) Body weight monitoring along the treatment. Both groups lost weight during the treatment, though Nutlin-3a–treated mice had a lower body weight compared with vehicle-treated mice. (C) Blood urea nitrogen (BUN) levels over the treatment increased in both groups, being higher in Nutlin-3a–treated mice than in vehicle-treated mice. *P = 0.0039, t test, n = 7/group. (D) Immunofluorescence (IF) image of control mouse in upper panel and of Nutlin-3a–treated mouse in lower panel. Magnification, ×60. (E) IF quantification of number of podocytes. Nutlin-3a–treated displayed a lower number of podocytes (6.50 ± 0.14) than vehicle-treated mice (5.84 ± 0.54). *P = 0.0139, Wilcoxon rank sum test. db/db DMSO, n = 4; db/db Nutlin-3a, n = 6. (F) Representative photomicrograph of TP53 staining in the wild-type and db/db mice. Nutlin-3a treatment in db/db mice causes upregulation and nuclear shift of TP53 in renal cells. Representative from n = 5 for each group except wild type treated with Nutlin-3a (n = 4). Magnification, ×200. Error bars in B represent SE. For box-and-whisker plots in C and E, the horizontal line in each box represents the median. The whiskers extend to 1.5 × (third quartile – first quartile).