Abstract
Adenosine kinase (ADK) plays the major role in cardiac adenosine metabolism, so that inhibition of ADK increases myocardial adenosine levels. While the cardioprotective actions of extracellular adenosine against ischemia/reperfusion (I/R) are well-established, the role of cellular adenosine in protection against I/R remains unknown. Here we investigated the role of cellular adenosine in epigenetic regulation on cardiomyocyte gene expression, glucose metabolism and tolerance to I/R. Evans blue/TTC staining and echocardiography were used to assess the extent of I/R injury in mice. Glucose metabolism was evaluated by positron emission tomography and computed tomography (PET/CT). Methylated DNA immunoprecipitation (MeDIP) and bisulfite sequencing PCR (BSP) were used to evaluate DNA methylation. Lentiviral/adenovirus transduction was used to overexpress DNMT1, and the OSI-906 was administered to inhibit IGF-1. Cardiomyocyte-specific ADK/IGF-1-knockout mice were used for mechanistic experiments.Cardiomyocyte-specific ADK knockout enhanced glucose metabolism and ameliorated myocardial I/R injury in vivo. Mechanistically, ADK deletion caused cellular adenosine accumulation, decreased DNA methyltransferase 1 (DNMT1) expression and caused hypomethylation of multiple metabolic genes, including insulin growth factor 1 (IGF-1). DNMT1 overexpression abrogated these beneficial effects by enhancing apoptosis and decreasing IGF-1 expression. Inhibition of IGF-1 signaling with OSI-906 or genetic knocking down of IGF-1 also abrogated the cardioprotective effects of ADK knockout, revealing the therapeutic potential of increasing IGF-1 expression in attenuating myocardial I/R injury. In conclusion, the present study demonstrated that cardiomyocyte ADK deletion ameliorates myocardial I/R injury via epigenetic upregulation of IGF-1 expression via the cardiomyocyte adenosine/DNMT1/IGF-1 axis.