Temporal and gefitinib-sensitive regulation of cardiac cytokine expression via chronic β-adrenergic receptor stimulation

Abstract

Chronic stimulation of β-adrenergic receptors (βAR) can promote survival signaling via transactivation of epidermal growth factor receptor (EGFR) but ultimately alters cardiac structure and contractility over time, in part via enhanced cytokine signaling. We hypothesized that chronic catecholamine signaling will have a temporal impact on cardiac transcript expression in vivo, in particular cytokines, and that EGFR transactivation plays a role in this process. C57BL/6 mice underwent infusion with vehicle or isoproterenol (Iso)±gefitinib (Gef) for 1 or 2 wk. Cardiac contractility decreased following 2 wk of Iso treatment, while cardiac hypertrophy, fibrosis, and apoptosis were enhanced at both timepoints. Inclusion of Gef preserved contractility, blocked Iso-induced apoptosis, and prevented hypertrophy at the 2-wk timepoint, but caused fibrosis on its own. RNAseq analysis revealed hundreds of cardiac transcripts altered by Iso at each timepoint with subsequent RT-quantitative PCR validation confirming distinct temporal patterns of transcript regulation, including those involved in cardiac remodeling and survival signaling, as well as numerous cytokines. Although Gef infusion alone did not significantly alter cytokine expression, it abrogated the Iso-mediated changes in a majority of the βAR-sensitive cytokines, including CCL2 and TNF-α. Additionally, the impact of βAR-dependent EGFR transactivation on the acute regulation of cytokine transcript expression was assessed in isolated cardiomyocytes and in cardiac fibroblasts, where the majority of Iso-dependent, and EGFR-sensitive, changes in cytokines occurred. Overall, coincident with changes in cardiac structure and contractility, βAR stimulation dynamically alters cardiac transcript expression over time, including numerous cytokines that are regulated via EGFR-dependent signaling.

Orphan Nuclear Receptor Nur77 Inhibits Cardiac Hypertrophic Response to Beta-Adrenergic Stimulation

“…Accumulating evidence suggests that NR4A receptors play essential roles in the development of atherosclerosis, restenosis, and angiogenesis (17,18,33). However, the functional role of the NR4A receptor in cardiomyocyte biology remains largely obscured, although several studies suggest that the NR4A receptors are highly expressed in the heart and that their expression is regulated by several external pathological stimuli, such as oxidative stress, pressure overload, and ␤-AR activation (19,20,34). In the present study, we sought to examine the role of Nur77 in cardiac hypertrophy and found that the expression of Nur77 is substantially increased in response to a wide range of hypertrophic stimuli.…”

Expression and Function of the Epidermal Growth Factor Receptor in Physiology and Disease

“…Transgenic mice expressing ␤ 1 AR with a G protein-coupled receptor kinase mutation fail to induce EGFR transactivation and develop left ventricular dilation and cardiac dysfunction when treated with isoproterenol. Similarly, mice cotreated with isoproterenol and erlotinib experience increased myocardial apoptosis, left ventricular dilation, and decreases in cardiac function; gefitinib, another EGFR TKI, prevents cardiac hypertrophy as a result of isoproterenol treatment but stimulates cardiac fibrosis when used alone (193) (FIGURE 7). …”

Epidermal Growth Factor Receptor Transactivation: Mechanisms, Pathophysiology, and Potential Therapies in the Cardiovascular System

“…Furthermore, mice co-treated with isoproterenol and erlotinib show marked reduction in fractional shortening, increased left ventricular diastolic dimension, and an increase in myocardial apoptosis (92). In contrast, gefitinib blocks cardiac hypertrophy induced by isoproterenol in these mice, but also induces cardiac fibrosis when treated alone (109). …”