Calcium/calmodulin-dependent protein kinase II couples Wnt signaling with histone deacetylase 4 and mediates dishevelled-induced cardiomyopathy.

Activation of Wnt signaling results in maladaptive cardiac remodeling and cardiomyopathy. Recently, calcium/calmodulin-dependent protein kinase II (CaMKII) was reported to be a pivotal participant in myocardial remodeling. Because CaMKII was suggested as a downstream target of noncanonical Wnt signaling, we aimed to elucidate the role of CaMKII in dishevelled-1-induced cardiomyopathy and the mechanisms underlying its function. Dishevelled-1-induced cardiomyopathy was reversed by deletion of neither CaMKIIδ nor CaMKIIγ. Therefore, dishevelled-1-transgenic mice were crossed with CaMKIIδγ double-knockout mice. These mice displayed a normal cardiac phenotype without cardiac hypertrophy, fibrosis, apoptosis, or left ventricular dysfunction. Further mechanistic analyses unveiled that CaMKIIδγ couples noncanonical Wnt signaling to histone deacetylase 4 and myosin enhancer factor 2. Therefore, our findings indicate that the axis, consisting of dishevelled-1, CaMKII, histone deacetylase 4, and myosin enhancer factor 2, is an attractive therapeutic target for prevention of cardiac remodeling and its progression to left ventricular dysfunction.

Dapper-1 is essential for Wnt5a induced cardiomyocyte hypertrophy by regulating the Wnt/PCP pathway.

The Wnt signaling pathway was identified as crucial mediator of cardiomyocyte hypertrophy. In this study we found that activation of non-canonical Wnt signaling by Wnt5a stimulates protein synthesis and enlargement of cardiomyocyte surface area. These hypertrophic features were inhibited in Dapper-1 (Dpr1) depleted cells. On the molecular level, we observed inhibition of the non-canonical Wnt/planar-cell-polarity (PCP) pathway denoted by reduction of c-jun-n-terminal-kinase (JNK) phosphorylation. Upstream of JNK, increased protein levels of the Wnt/PCP trans-membrane receptor van-Gogh-like-2 (Vangl2) were observed along with an enrichment of Vangl2 in perinuclear located vesicles. The findings suggest that Dpr1 is essential for execution of the Wnt/PCP pathway and regulation of the Vangl2/JNK axis. Depletion of Dpr1 inhibits non-canonical Wnt signaling induced cardiomyocyte hypertrophy by blocking Wnt/PCP signaling.

Dapper-1 induces myocardial remodeling through activation of canonical Wnt signaling in cardiomyocytes.

Heart failure has an increasing contribution to cardiovascular disease burden and is governed by the myocardial remodeling process. The contribution of Wnt signaling to cardiac remodeling has recently drawn significant attention. Here, we report that upregulation of Dapper-1 in a transgenic mouse model activates the canonical/ß-catenin-dependent Wnt pathway through dishevelled-2. These mice exhibited increased heart weight/tibia length ratio, myocyte cross-sectional area, and upregulation of hypertrophic marker genes compared with wild-type mice. Furthermore, impairment of left ventricular systolic and diastolic function was observed in all indicating features of myocardial remodeling. Depletion of Dapper-1 and dishevelled-2 in cardiomyocytes demonstrated that Dapper-1 functions upstream of dishevelled-2 and that activity of both Dapper-1 and dishevelled-2 is essential for activating canonical Wnt signaling. Moreover, Dapper-1 depletion alleviated Wnt3a- and phenylephrine-induced cardiomyocyte hypertrophy. These observations provide evidence that Dapper-1-mediated activation of canonical Wnt signaling is necessary and sufficient to induce cardiomyocyte hypertrophy. Inhibition of this pathway may thus serve as a novel therapeutic strategy for alleviating cardiac hypertrophy.