CCN2 exerts direct cytoprotective actions in adult cardiac myocytes by activation of the PI3-kinase/Akt/GSK-3β signaling pathway

Abstract

We recently reported that transgenic mice with cardiac-restricted overexpression of CCN2/CTGF have substantially increased tolerance towards ischemia/reperfusion injury. The purpose of this study was to investigate to what extent fully differentiated cardiac myocytes are direct targets of CCN2, and to resolve the signaling mechanisms that convey the cardioprotective actions of CCN2. Akt and GSK-3β were identified as putative intermediaries of intracellular signaling stimulated by recombinant human CCN2 (rhCCN2). Concentration-effect experiments revealed CCN2-stimulated phosphorylation of Akt (Ser473) and downstream GSK-3β (Ser9) with EC50 ~250 nmol/L. CCN2-stimulated phosphorylation of Akt and GSK-3β was sensitive to inhibition of PI3-kinase (LY294002). Phosphorylation of GSK-3β was also sensitive to Akt-inhibition (API-2), demonstrating CCN2-engendered activation of a PI3-kinase/Akt/GSK-3β-signaling pathway. A C-terminal peptide fragment of CCN2 (11.2 kD) displayed partial agonist activity, while two short peptides derived from the Thrombospondin- and the IGFBP- homology domains of CCN2, respectively, additively inhibited rhCCN2-stimulated Akt-phosphorylation. The viability of cardiac myocytes subjected to hypoxia/reoxygenation injury or doxorubicin-induced oxidative stress was assessed by assays of adenylate kinase and lactate dehydrogenase released from dying cells. Cardiac myocytes exposed to CCN2 displayed increased tolerance towards hypoxia/reoxygenation and doxorubicin-induced oxidative stress, an effect that was abrogated by inhibition of PI3-kinase. The cytoprotective actions of CCN2 reflected in the transcriptome of CCN2-stimulated cardiac myocytes (anti-apoptosis, stress, and wound-response gene programs). In conclusion, this study discloses the novel findings that cardiac myocytes are CCN2 target cells in which CCN2 increases tolerance towards hypoxia and oxidative stress via PI3-kinase-dependent Akt/GSK-3β signaling.

Proteomic Comparison of the Secreted Factors of Mesenchymal Stem Cells from Bone Marrow, Adipose Tissue and Dental Pulp

“…For instance, it has reported that combination of chemokine (C-C motif) ligand 2 (CCL2) and sialic acid binding Ig-like lectin 9 (SIGLEC9), which are produced from DPSCs, is needed to enhance repair of the spinal cord [27]. We identified several secreted factors which have been reported as cardioprotective, including CTGF, MYDGF, DKK3, and follistatin like 1 (FSTL1) [21,[28][29][30]. However, single treatment of CTGF, DKK3 and FSTL1, did not enhance cell viability in an in vitro OGD-assay (data not shown).…”

p63RhoGEF regulates auto- and paracrine signaling in cardiac fibroblasts

“…In a recent work, it was convincingly demonstrated that neither its heart-specific deletion nor its overexpression had any influence on cardiac remodeling and function with aging or after multiple stress stimuli [44]. This is in sharp contrast to other mouse studies demonstrating either a beneficial effect of CTGF for cardiomyocyte survival or a detrimental effect on cardiac fibrosis after TAC [8][9][10][11]. Thus further unbiased studies like secretome analyses have to be performed in order to identify responsible factors downstream of p63RhoGEF-RhoA explaining the observed changes in tissue properties.…”

“…By anchoring to the ECM, CTGF is thought to coordinate the micro-milieu in the myocardium by keeping diverse growth factors in close vicinity to cardiac cells and their receptors. However, in vivo data on the role of CTGF are surprisingly conflicting ranging from a pro-fibrotic to a cardiomyocyte protective function [8][9][10][11]. Similar to the still obscure role of CTGF, there is not much data available how the regulation of CTGF expression and secretion is achieved in cardiac cells.…”

Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead

“…GSK-3β is tightly regulated by the survival pathway represented by phosphatidylinositol-3 kinase (PI3K) and its downstream effector the protein kinase B (Akt) (Moe et al, 2013). Accumulating evidence has shown that nuclear translocation of Nrf2 might be induced by a decrease of GSK-3β phosphorylation (Ser9) (Rojo et al, 2012).…”