The serine/threonine kinase Akt, a key downstream kinase of the IGF1/PI3K pathway has a profound effect on cardiac function both in vivo and in vivo. Transgenic mice over-expressing an active mutant of Akt induced an increase of inotropism in vivo and in vitro and of lusotropism in vitro, indicating the role of Akt in physiologic hypertrophy.
New data from us show that Akt induces the phosphorylation of phospholamban (PLB), a critical regulator of SERCA2a, the pump responsible for Ca2+uptake from the sarcoplasmic reticulum (SR) at Thr-17, a residue phosphorylated by Ca2+/Calmodulin-dependent kinase 2 delta (CAMK).
Thus, our working hypothesis is that Akt activates CAMK in the SR compartment and that the inotropic effects of Akt are partially or totally dependent on this effect. Preliminary data show also that stimulation of cardiomyocytes (CMCs) with IGF-1, which externally activates Akt, induces CAMK-dependent PLB phosphorylation.
The aims of our project are therefore
- To characterize the role of CAMK in mediating the effects of Akt on inotropism and lustropism, through biochemical and functional experiments on cardiac myocytes and on isolated SR vescicles. The relevance of AKT-dependent CAMK activation at the level of organ physiology will be addressed by generating inducible and tissue-specific knockout mice of both CAMK 2 delta and Akt2. We will generate also a knockout mouse deleted in the nuclear localization signal of CAMK2 delta to determine the importance of subcellular localization in CAMK signalling
- To establish whether Akt can improve cardiac function in heart failure. For this, MLP knockout mice, a model of dilatative cardiomyopathy, will be crossed with E40K Akt transgenic mice or treated with Akt by myocardial gene transfer.
As a whole, our study aims to define how Akt modulates cardiac contractility and whether the manipulation of the Akt pathway can be used to improve cardiac function in heart failure.
Field of science
- /medical and health sciences/medical biotechnology/genetic engineering/gene therapy
Call for proposal
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