Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome–associated PTPN11 mutation
Talita M. Marin, … , Benjamin G. Neel, Maria I. Kontaridis
Talita M. Marin, … , Benjamin G. Neel, Maria I. Kontaridis
Published February 21, 2011
Citation Information: J Clin Invest. 2011;121(3):1026-1043. https://doi.org/10.1172/JCI44972.
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Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome–associated PTPN11 mutation

Abstract

LEOPARD syndrome (LS) is an autosomal dominant “RASopathy” that manifests with congenital heart disease. Nearly all cases of LS are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11) gene that encodes the SH2 domain-containing PTP-2 (SHP2). RASopathies typically affect components of the RAS/MAPK pathway, yet it remains unclear how PTPN11 mutations alter cellular signaling to produce LS phenotypes. We therefore generated knockin mice harboring the Ptpn11 mutation Y279C, one of the most common LS alleles. Ptpn11Y279C/+ (LS/+) mice recapitulated the human disorder, with short stature, craniofacial dysmorphia, and morphologic, histologic, echocardiographic, and molecular evidence of hypertrophic cardiomyopathy (HCM). Heart and/or cardiomyocyte lysates from LS/+ mice showed enhanced binding of Shp2 to Irs1, decreased Shp2 catalytic activity, and abrogated agonist-evoked Erk/Mapk signaling. LS/+ mice also exhibited increased basal and agonist-induced Akt and mTor activity. The cardiac defects in LS/+ mice were completely reversed by treatment with rapamycin, an inhibitor of mTOR. Our results demonstrate that LS mutations have dominant-negative effects in vivo, identify enhanced mTOR activity as critical for causing LS-associated HCM, and suggest that TOR inhibitors be considered for treatment of HCM in LS patients.

Authors

Talita M. Marin, Kimberly Keith, Benjamin Davies, David A. Conner, Prajna Guha, Demetrios Kalaitzidis, Xue Wu, Jessica Lauriol, Bo Wang, Michael Bauer, Roderick Bronson, Kleber G. Franchini, Benjamin G. Neel, Maria I. Kontaridis

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Figure 8

Agonist-evoked Erk MAPK activation is impaired in LS/+ mice.

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Agonist-evoked Erk MAPK activation is impaired in LS/+ mice. (A) Who...
(A) Whole heart lysates from either unstimulated or 10-minute insulin-stimulated (10 mU/g body weight) WT and LS/+ mice (8- to 10-week-old) were harvested, lysed, and immunoblotted with anti-phospho–Erk1/2 antibodies. The blot was reprobed with anti-Erk1/2 antibodies as a loading control. Each lane represents an individual animal. (B) Quantification of data collected from 4–6 animals for each group, each derived from 3 different experiments. *P < 0.01, ANOVA plus Bonferroni post-test when ANOVA was significant. Note the significant difference between basal and insulin-stimulated Erk activity of WT heart lysates, but the lack of significant differences between Erk activity in either basal WT and LS/+ hearts or in basal and insulin-stimulated LS/+ hearts, respectively. (C) Primary cardiomyocytes isolated from 8-week-old WT and LS/+ mice were collected, cultured overnight, and then either left unstimulated or stimulated for the indicated times with IGF-1 (10 nM), EGF (25 ng/ml), angiotensin II (100 nmol/l), or IL-6 (10 ng/ml). Data are representative of n = 3 independent experiments. Cell lysates were immunoblotted with anti-phospho–Erk1/2 antibodies, and then membranes were reprobed with anti-Erk1 antibodies to control for loading.