Myofibroblast β2 adrenergic signaling amplifies cardiac hypertrophy in mice

• Published in: Biochemical and biophysical research communications 2019-02, Vol.510 (1), p.149-155
• Main Authors: Imaeda, Atsuki, Tanaka, Shota, Tonegawa, Kota, Fuchigami, Shota, Obana, Masanori, Maeda, Makiko, Kihara, Miho, Kiyonari, Hiroshi, Conway, Simon J., Fujio, Yasushi, Nakayama, Hiroyuki
• Format: Article
• Language: English
• Subjects: Adrenergic beta-2 Receptor Agonists - pharmacology; Animals; Cardiac fibroblast; Cardiac hypertrophy; Cardiomegaly - etiology; Cyclic AMP-Dependent Protein Kinases - adverse effects; Cyclic AMP-Dependent Protein Kinases - genetics; Isoproterenol - pharmacology; Mice; Mice, Transgenic; Myofibroblasts - metabolism; Paracrine Communication; Paracrine effect; Protein kinase A; Rats; Receptors, Adrenergic, beta-2 - metabolism; Signal Transduction; β-adrenergic receptor
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2019.01.070

Abnormal β-adrenergic signaling plays a central role in human heart failure. In mice, chronic β-adrenergic receptor (βAR) stimulation elicits cardiac hypertrophy. It has been reported that cultured cardiac fibroblasts express βAR; however, the functional in vivo requirement of βAR signaling in cardiac fibroblasts during the development of cardiac hypertrophy remains elusive. β2AR null mice exhibited attenuated hypertrophic responses to chronic βAR stimulation upon continuous infusion of an agonist, isoprenaline (ISO), compared to those in wildtype controls, suggesting that β2AR activation in the heart induces pro-hypertrophic effects in mice. Since β2AR signaling is protective in cardiomyocytes, we focused on β2AR signaling in cardiac myofibroblasts. To determine whether β2AR signaling in myofibroblasts affects cardiac hypertrophy, we generated myofibroblast-specific transgenic mice (TG) with the catalytic subunit of protein kinase A (PKAcα) using Cre-loxP system. Myofibroblast-specific PKAcα overexpression resulted in enhanced heart weight normalized to body weight ratio, associated with an enlargement of cardiomyocytes at 12 weeks of age, indicating that myofibroblast-specific activation of PKA mediates cardiac hypertrophy in mice. Neonatal rat cardiomyocytes stimulated with conditioned media from TG cardiac fibroblasts likewise exhibited significantly more growth than those from controls. Thus, β2AR signaling in myofibroblasts plays a substantial role in ISO-induced cardiac hypertrophy, possibly due to a paracrine effect. β2AR signaling in cardiac myofibroblasts may represent a promising target for development of novel therapies for cardiac hypertrophy. •We elucidated the role of fibroblast-specific βAR signaling in cardiac hypertrophy.•β2ARKO mice had reduced hypertrophic responses to chronic βAR stimulation.•Fibroblast-specific activation of PKA mediated cardiac hypertrophy in mice.•Transgenic conditioned media stimulated growth of neonatal rat cardiomyocytes.•Fibroblast β2AR promotes ISO-induced cardiac hypertrophy in a paracrine manner.