Gab family proteins are essential for postnatal maintenance of cardiac function via neuregulin-1/ErbB signaling
Yoshikazu Nakaoka, … , Toshio Hirano, Naoki Mochizuki
Yoshikazu Nakaoka, … , Toshio Hirano, Naoki Mochizuki
Published July 2, 2007
Citation Information: J Clin Invest. 2007;117(7):1771-1781. https://doi.org/10.1172/JCI30651.
View: Text | PDF
Research Article Cardiology

Gab family proteins are essential for postnatal maintenance of cardiac function via neuregulin-1/ErbB signaling

Abstract

Grb2-associated binder (Gab) family of scaffolding adaptor proteins coordinate signaling cascades downstream of growth factor and cytokine receptors. In the heart, among EGF family members, neuregulin-1β (NRG-1β, a paracrine factor produced from endothelium) induced remarkable tyrosine phosphorylation of Gab1 and Gab2 via erythroblastic leukemia viral oncogene (ErbB) receptors. We examined the role of Gab family proteins in NRG-1β/ErbB-mediated signal in the heart by creating cardiomyocyte-specific Gab1/Gab2 double knockout mice (DKO mice). Although DKO mice were viable, they exhibited marked ventricular dilatation and reduced contractility with aging. DKO mice showed high mortality after birth because of heart failure. In addition, we noticed remarkable endocardial fibroelastosis and increase of abnormally dilated vessels in the ventricles of DKO mice. NRG-1β induced activation of both ERK and AKT in the hearts of control mice but not in those of DKO mice. Using DNA microarray analysis, we found that stimulation with NRG-1β upregulated expression of an endothelium-stabilizing factor, angiopoietin 1, in the hearts of control mice but not in those of DKO mice, which accounted for the pathological abnormalities in the DKO hearts. Taken together, our observations indicated that in the NRG-1β/ErbB signaling, Gab1 and Gab2 of the myocardium are essential for both maintenance of myocardial function and stabilization of cardiac capillary and endocardial endothelium in the postnatal heart.

Authors

Yoshikazu Nakaoka, Keigo Nishida, Masahiro Narimatsu, Atsunori Kamiya, Takashi Minami, Hirofumi Sawa, Katsuya Okawa, Yasushi Fujio, Tatsuya Koyama, Makiko Maeda, Manami Sone, Satoru Yamasaki, Yuji Arai, Gou Young Koh, Tatsuhiko Kodama, Hisao Hirota, Kinya Otsu, Toshio Hirano, Naoki Mochizuki

×

Figure 2

Generation of DKO mice.

Options: View larger image (or click on image) Download as PowerPoint
Generation of DKO mice. (A) Schematic illustration of genomic structure ...
(A) Schematic illustration of genomic structure of the Gab1 wild-type, Gab1 flox, and Gab1-deleted alleles and a targeting vector. loxP sequences are indicated by black triangles. Restriction enzyme sites for EcoRI and HindIII are indicated as R and H, respectively. Fragments detected by the probe (short bold line) used for Southern blot analysis after digestion of genomic DNA with EcoRI and HindIII are indicated as solid lines measuring 4.3 kb, 3.8 kb, and 5.7 kb. HSV-TK, herpes simplex virus–thymidine kinase. (B) Southern blot analysis demonstrated recombination of the Gab1flox allele in the heart, but not in the kidney, of Gab1flox/flox mice, which possessed the α-MHC–Cre allele. (C) Following IP, expression of Gab1 and Gab2 was examined by IB using anti-Gab1 (top row) and anti-Gab2 (middle row) serums. SHP2 was examined as a loading control (bottom row). Note that 2 isoforms of Gab1 were detected at the different MW exclusively in the heart (arrows) and that the high-MW Gab1 isoform in the heart was completely depleted in Gab1CKO and DKO. The low-MW Gab1 was also reduced by 80% in the heart of Gab1CKO and DKO mice compared with control and Gab2KO mice.