GSK-3α directly regulates β-adrenergic signaling and the response of the heart to hemodynamic stress in mice
Jibin Zhou, … , Erhe Gao, Thomas Force
Jibin Zhou, … , Erhe Gao, Thomas Force
Published June 1, 2010
Citation Information: J Clin Invest. 2010;120(7):2280-2291. https://doi.org/10.1172/JCI41407.
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Research Article Cardiology

GSK-3α directly regulates β-adrenergic signaling and the response of the heart to hemodynamic stress in mice

Abstract

The glycogen synthase kinase-3 (GSK-3) family of serine/threonine kinases consists of 2 highly related isoforms, α and β. Although GSK-3β has an important role in cardiac development, much remains unknown about the function of either GSK-3 isoform in the postnatal heart. Herein, we present what we believe to be the first studies defining the role of GSK-3α in the mouse heart using gene targeting. Gsk3a–/– mice over 2 months of age developed progressive cardiomyocyte and cardiac hypertrophy and contractile dysfunction. Following thoracic aortic constriction in young mice, we observed enhanced hypertrophy that rapidly transitioned to ventricular dilatation and contractile dysfunction. Surprisingly, markedly impaired β-adrenergic responsiveness was found at both the organ and cellular level. This phenotype was reproduced by acute treatment of WT cardiomyocytes with a small molecule GSK-3 inhibitor, confirming that the response was not due to a chronic adaptation to LV dysfunction. Thus, GSK-3α appears to be the central regulator of a striking range of essential processes, including acute and direct positive regulation of β-adrenergic responsiveness. In the absence of GSK-3α, the heart cannot respond effectively to hemodynamic stress and rapidly fails. Our findings identify what we believe to be a new paradigm of regulation of β-adrenergic signaling and raise concerns given the rapid expansion of drug development targeting GSK-3.

Authors

Jibin Zhou, Hind Lal, Xiongwen Chen, Xiying Shang, Jianliang Song, Yingxin Li, Risto Kerkela, Bradley W. Doble, Katrina MacAulay, Morgan DeCaul, Walter J. Koch, John Farber, James Woodgett, Erhe Gao, Thomas Force

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Figure 8

GSK-3α regulates isoproterenol-induced cAMP production.

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GSK-3α regulates isoproterenol-induced cAMP production. (A–C) Studies we...
(A–C) Studies were in 4-month-old mice. (A) cAMP production in the intact mouse heart. KO and WT mice were injected with isoproterenol (1 ng/g BW) versus vehicle. Fifteen minutes later, hearts were excised, and cAMP production was determined. n = 4 mice per condition. (B) cAMP production in response to vehicle versus isoproterenol (5 μM, 15 minutes) in cardiomyocytes isolated from KO and WT mice (n = 6), with 4 × 105 myocytes per assay. LVM, LV myocyte. (C) Inhibition of isoproterenol-induced contractile function by a GSK-3 inhibitor. Cardiomyocytes were isolated from WT and KO mice (n = 6). Fractional shortening was determined at baseline, after isoproterenol (5 μM, 10 minutes), and in WT cells pretreated with SB415286 (10 μM, 60 minutes). Contractile function increased with isoproterenol in WT cells but not in KO cells or SB415286-treated WT cells. n = 14 cells for WT and KO mice; n = 12 cells for WT plus SB415286 mice. (D) SB415286 blocks cAMP production in NRVMs. NRVMs were pretreated with SB415286 or vehicle, followed by isoproterenol versus vehicle. SB415286 reduced isoproterenol-induced cAMP production but not forskolin-induced cAMP production. (E) Reduced isoproterenol-induced phosphorylation of PLN in the KO mice. Two-month-old WT and KO mice underwent isoproterenol infusion (1 μg/kg BW) for 15 minutes. Lysates were immunoblotted for PLN phosphorylated at Ser16 (PKA site), Thr17 (CamKII site), total PLN, and GAPDH. (F) Increased isoproterenol-induced ERK1/2 activation in the KO mice. Mice were treated with isoproterenol versus vehicle as above, and cell lysates were immunoblotted for phospho-ERK1/2, total ERK1/2, phospho-p38, total p38, or GAPDH.