Adenovirus-Mediated Overexpression of Diacylglycerol Kinase-ζ Inhibits Endothelin-1–Induced Cardiomyocyte Hypertrophy

Abstract

Background-Diacylglycerol (DAG) is a lipid second messenger that transiently accumulates in cells stimulated by endothelin-1 (ET-1) and other G␣q protein-coupled receptor agonists. Diacylglycerol kinase (DGK) is thought to be an enzyme that controls the cellular levels of DAG by converting it to phosphatidic acid; however, the functional role of DGK has not been examined in cardiomyocytes. Because DGK inactivates DAG, a strong activator of protein kinase C (PKC), we hypothesized that DGK inhibited ET-1-induced activation of a DAG-PKC signaling cascade and subsequent cardiomyocyte hypertrophy. Methods and Results-Real-time reverse transcription-polymerase chain reaction demonstrated a significant increase of DGK-mRNA by ET-1 in cardiomyocytes. To determine the functional role of DGK-, we overexpressed DGK-in cardiomyocytes using a recombinant adenovirus encoding rat DGK-(Ad-DGK). ET-1-induced translocation of PKC-⑀ was blocked by Ad-DGK (PϽ0.01). Ad-DGK also inhibited ET-1-induced activation of extracellular signal-regulated kinase (PϽ0.01). Luciferase reporter assay revealed that ET-1-mediated increase of activator protein-1 (AP1) DNA-binding activity was significantly inhibited by DGK-(PϽ0.01). In cardiomyocytes transfected with DGK-, ET-1 failed to cause gene induction of atrial natriuretic factor, increases in [

Diacylglycerol Kinase .ZETA.Rescues G.ALPHA.q-Induced Heart Failure in Transgenic Mice

“…3 In particular, numerous investigations have demonstrated the importance of the G q-mediated signaling in the development of cardiac hypertrophy and HF. 7,8,27 We previously showed that DGK inhibits GPCR agonist-induced hypertrophic signaling and resultant cardiac hypertrophy in vitro and in vivo, 16,17 and recently we also showed that DGK attenuates LV remodeling and improves survival after myocardial infarction. 28 DGK suppresses the cardiac hypertrophy and fibrosis caused by pressure overload.…”

“…11 Our previous in vitro study using cultured rat neonatal cardiomyocytes has shown that DGK blocks endothelin-1-induced increases in protein synthesis concomitant with increases in cell size and reactivation of fetal genes via the inhibition of PKC . 16 In addition, DGK inhibits translocation of PKC and upregulation of ANF after GPCR agonists, such as angiotensin II and phenylephrine infusion, in mice. 17 These data are consistent with the present study's result that the inhibition of PKC by DGK might contribute to suppression of gene induction of ANF, -MHC, and BNP (Fig 5) and attenuation of increases in cross-sectional cardiomyocyte surface area (Fig 6).…”

“…16,17,20 To examine mRNA expression levels of atrial natriuretic factor (ANF), -MHC, B-type natriuretic peptide (BNP), -skeletal actin, collagen type I, and collagen type III, real-time PCR amplification was performed as reported previously. 16,17,20 Reagents were purchased from Roche Diagnostics Japan (Tokyo, Japan). Amplification was performed using a LightCycler DNA Master SYBR Green I in a 20-l volume reaction and analyzed using LightCycler Software Ver.3.5 (Roche Diagnostics Japan).…”

Phorbol 12-Myristate 13-Acetate-dependent Protein Kinase Cδ-Tyr311 Phosphorylation in Cardiomyocyte Caveolae

“…In fact, there is recent evidence that NE activates diacyglycerol kinase-leading to feedback inhibition of PKC in the caveolae/ raft fraction of rat mesenteric small arteries (48). The relevance of this finding to PKC regulation in cardiomyocytes, where a different diacyglycerol kinase isoform (namely diacyglycerol kinase-) negatively regulates hypertrophic signaling responses to G protein-coupled receptor agonists requires further study (50,51).…”

Lipid Messenger, Diacylglycerol, and its Regulator, Diacylglycerol Kinase, in Cells, Organs, and Animals: History and Perspective

“…Previous studies of human heart failure and animal models of heart failure including genetically engineered mice have clearly shown that the activation of PKC plays a critical role under these conditions (Bowling et al 1999;Takeishi et al 1998Takeishi et al , 1999Takeishi et al , 2000, suggesting that DGK may be closely involved in the cardiac dysfunction. In this regard, DGKζ has been shown to block endothelin-1-induced activation of the PKCε -ERK-AP1 signaling pathway, atrial natriuretic factor gene induction, and resultant cardiomyocyte hypertrophy (Takahashi et al 2005). Furthermore, a recent study should be noted on the evaluation of possible roles of DGKζ in the cardiac function using an animal model of transgenic mice with cardiac-specifi c overexpression of DGKζ (DGKζ -TG) (Arimoto et al 2006).…”