Dysfunction of the MDM2/p53 axis is linked to premature aging
Davor Lessel, … , Carol Prives, Christian Kubisch
Davor Lessel, … , Carol Prives, Christian Kubisch
Published August 28, 2017
Citation Information: J Clin Invest. 2017;127(10):3598-3608. https://doi.org/10.1172/JCI92171.
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Concise Communication Aging Genetics

Dysfunction of the MDM2/p53 axis is linked to premature aging

Abstract

The tumor suppressor p53, a master regulator of the cellular response to stress, is tightly regulated by the E3 ubiquitin ligase MDM2 via an autoregulatory feedback loop. In addition to its well-established role in tumorigenesis, p53 has also been associated with aging in mice. Several mouse models with aberrantly increased p53 activity display signs of premature aging. However, the relationship between dysfunction of the MDM2/p53 axis and human aging remains elusive. Here, we have identified an antiterminating homozygous germline mutation in MDM2 in a patient affected by a segmental progeroid syndrome. We show that this mutation abrogates MDM2 activity, thereby resulting in enhanced levels and stability of p53. Analysis of the patient’s primary cells, genome-edited cells, and in vitro and in vivo analyses confirmed the MDM2 mutation’s aberrant regulation of p53 activity. Functional data from a zebrafish model further demonstrated that mutant Mdm2 was unable to rescue a p53-induced apoptotic phenotype. Altogether, our findings indicate that mutant MDM2 is a likely driver of the observed segmental form of progeria.

Authors

Davor Lessel, Danyi Wu, Carlos Trujillo, Thomas Ramezani, Ivana Lessel, Mohammad K. Alwasiyah, Bidisha Saha, Fuki M. Hisama, Katrin Rading, Ingrid Goebel, Petra Schütz, Günter Speit, Josef Högel, Holger Thiele, Gudrun Nürnberg, Peter Nürnberg, Matthias Hammerschmidt, Yan Zhu, David R. Tong, Chen Katz, George M. Martin, Junko Oshima, Carol Prives, Christian Kubisch

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Figure 2

The antiterminating MDM2 mutation is defective in its regulation of p53.

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The antiterminating MDM2 mutation is defective in its regulation of p53....
(A) Protein levels of MDM2, p53, and actin in control and IV:7 fibroblasts treated with vehicle DMSO (–), Nutlin-3 (N, 10 μM), or daunorubicin (D, 0.1 mg/ml) for 24 hours. Immunoblot with the indicated antibodies. Graph shows the fold change of basal p53 levels over actin levels from 5 independent experiments. (B) Protein degradation rates of MDM2 and p53 in fibroblasts via CHX chase. Immunoblots show results of control 1 and IV:7 fibroblasts harvested at the indicated times (minutes) after CHX (100 μg/ml) treatment. Graphs show protein quantification normalized to actin (using ImageJ and GraphPad Prism software) and the half-lives of MDM2 (control 1: 62 min; IV:7: 92 min) and p53 (control 1: 45 min; IV:7: 82 min). (C) Effects of proteasome inhibition on MDM2 and p53 levels. Immunoblot of control fibroblasts (controls 3, 4, and 1) and IV:7 fibroblasts treated with vehicle (DMSO) or MG132 (25 μM) for 6 hours. Graph shows protein quantification (using ImageJ) and normalization to actin. Fold recovery was calculated by comparing p53 or MDM2 values from treated cells with those of untreated cells. (D) Subcellular localization of MDM2 and p53 in control 1 and IV:7 fibroblasts treated with vehicle (DMSO) or Nutlin-3 (10 μM) for 24 hours. Original magnification, ×63. (E) U2OS genome-edited cells expressing WT/WT and MUT/MUT MDM2 with no p53 were treated with vehicle (DMSO) or the proteasome inhibitor MG132 (25 μM) for 6 hours before harvesting and immunoblotting. In A and B, error bars represent mean ± standard deviation. In C, error bars represent mean ± SEM.