Interleukin-18 Is a Pro-hypertrophic Cytokine That Acts through a Phosphatidylinositol 3-Kinase-Phosphoinositide-dependent Kinase-1-Akt-GATA4 Signaling Pathway in Cardiomyocytes

Abstract

In patients with congestive heart failure, high serum levels of the proinflammatory cytokine interleukin (IL)-18 were reported. A positive correlation was described between serum IL-18 levels and the disease severity. IL-18 has also been shown to induce atrial natriuretic factor (ANF) gene expression in adult cardiomyocytes. Because re-expression of the fetal gene ANF is mostly associated with hypertrophy, a hallmark of heart failure, we hypothesized that IL-18 induces cardiomyocyte hypertrophy. Treatment of the cardiomyocyte cell line HL-1 with IL-18 induced hypertrophy as characterized by increases in protein synthesis, phosphorylated p70 S6 kinase, and ribosomal S6 protein levels as well as cell surface area. Furthermore, IL-18 induced ANF gene transcription in a time-dependent manner as evidenced by increased ANF secretion and ANF promoter-driven reporter gene activity. Investigation into possible signal transduction pathways mediating IL-18 effects revealed that IL-18 activates phosphoinositide 3-kinase (PI3K), an effect that was blocked by wortmannin and LY-294002. IL-18 induced Akt phosphorylation and stimulated its activity, effects that were abolished by Akt inhibitor or knockdown. IL-18 stimulated GATA4 DNA binding activity and increased transcription of a reporter gene driven by multimerized GATA4-binding DNA elements. Pharmacological inhibition or knockdown studies revealed that IL-18 induced cardiomyocyte hypertrophy and ANF gene transcription via PI3K, PDK1, Akt, and GATA4. Most importantly, IL-18 induced ANF gene transcription and hypertrophy of neonatal rat ventricular myocytes via PI3K-, Akt-, and GATA4-dependent signaling. Together these data provide the first evidence that IL-18 induces cardiomyocyte hypertrophy via PI3K-dependent signaling, defines a mechanism of IL-18-mediated ANF gene transcription, and further supports a role for IL-18 in inflammatory heart diseases including heart failure.

Hydrogen Peroxide Induces Cell Cycle Arrest in Cardiomyoblast H9c2 Cells, Which Is Related to Hypertrophy

“…23) p21 has a wide specificity for substrates such as CDK4/6, CDK2, and Cdc2, leading to cell cycle arrest at multiple phases. 22 27,[32][33][34] Because ANP gene expression is mediated by the transcription factor GATA-4 and signaling pathways leading to cardiomyocyte hypertrophy activate GATA-4 under various hypertrophic conditions, 35,36) upregulation of ANP gene expression suggests activation of a signaling pathway leading to the development of hypertrophy. It is possible that H 2 O 2 activated the hypertrophic signaling pathway in H9c2 cells even in the presence of BAPTA-AM.…”

Carbon monoxide donors or heme oxygenase-1 (HO-1) overexpression blocks interleukin-18-mediated NF-κB–PTEN-dependent human cardiac endothelial cell death

“…Electrophoretic mobility shift (EMSA), ELISA, reporter assays NF-κB DNA-binding activity in nuclear protein extracts was analyzed by EMSA [9][10][11][12]. The following double-stranded oligonucleotides were used: consensus, 5′-AGTTGAGGGGACTTTCCCAGGC-3′; mutant, 5′-AGTTGAGGCGACTTTCCCAGGC-3′ (Santa Cruz Biotechnology, Santa Cruz, CA).…”

“…Isolation of whole cell homogenates, electrophoresis, electroblotting, and Western blotting using the ECL chemiluminescence detection system were previously described [9][10][11][12]. Mitochondrial and cytoplasmic fractions were prepared using the Mitochondrial Fractionation Kit (Active Motif).…”

“…IL-18 is a pleiotropic cytokine that promotes inflammation, hypertrophy, mitogenesis, and apoptosis, depending on the cell type [9][10][11]. As a pro-apoptotic cytokine, IL-18 induces endothelial cell death via activation of both the intrinsic and extrinsic pro-apoptotic signaling pathways [11].…”

Role of kallistatin in prevention of cardiac remodeling after chronic myocardial infarction

“…4,21 In addition, ANP, a cardiac hypertrophy marker, is activated in an Akt-dependent manner. 22 However, one study reported that short-term activation of Akt-induced cardiac hypertrophy without ANP gene expression. 23 Moreover, ERK is considered to be activated by mechanical stress, which induces a G-protein-coupled hypertrophic stimulation in heart failure.…”