Background: Exercise training's benefits in cardiovascular system have been well accepted, however, the underlying mechanism remains to be explored. Here, we report the initial functional characterization of an exercise-induced cardiac physiological hypertrophy associated novel lncRNA. Methods: Using lncRNA microarray profiling, we identified lncRNAs in contributing the modulation of exercise-induced cardiac growth that we termed Cardiac Physiological hypertrophy associated regulator (CPhar). Mice with Adeno-associated virus serotype 9 (AAV9) driving CPhar overexpression and knockdown were used in in-vivo experiments. Swim training was used to induce physiological cardiac hypertrophy in mice and ischemia reperfusion injury (IR/I) surgery was conducted to investigate the protective effects of CPhar in mice. To investigate the mechanisms of CPhar's function, we performed various analysis including RTqPCR, western blot, histology, cardiac function (by echocardiography), functional rescue experiments, mass spectrometry, in vitro RNA transcription, RNA pull down, RNA immunoprecipitation, chromatin immunoprecipitation assay, luciferase reporter assay, and coimmunoprecipitation assays. Results: We screened the lncRNAs in contributing the modulation of exercise-induced cardiac growth via lncRNA microarray profiling and found that CPhar was increased with exercise and was necessary for exercise-induced physiological cardiac growth. Gain- and loss- of function of CPhar regulated the expression of proliferation markers, hypertrophy, and apoptosis in cultured neonatal mouse cardiomyocytes (NMCMs). Overexpression of CPhar prevented myocardial ischemia reperfusion injury and cardiac dysfunction in vivo . We identified DDX17 as a binding partner of CPhar in regulating CPhar downstream factor ATF7 by sequestering C/EBPβ. Conclusions: Our study of this lncRNA CPhar provides new insights into the regulation of exercise-induced cardiac physiological growth, demonstrating the cardioprotective role of CPhar in the heart, as well as expanding our mechanistic understanding of lncRNA function.

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Background: Accumulated clinical trials and animal studies showed that Qiliqiangxin (QLQX), a traditional Chinese medicine formula containing extracts of 11 herbs, exerts beneficial effects on chronic heart failure (HF). Citri Reticulatae Pericarpium (CRP), one herbal medicine in QLQX, has been widely used in treatment against digestive, respiratory and cardiovascular diseases (CVDs) in China. However, the cardiac protective effects and mechanisms of CRP are still unclear.Methods: The effects of CRP were investigated in isoproterenol (ISO)-induced chronic HF mice model and neonatal rat ventricular cardiomyocytes (NRVMs) treated with ISO. Echocardiography was used to determine cardiac function. Hematoxylin-eosin (HE) staining and α-actinin immunofluorescent staining were used to measure cardiomyocyte size. Cardiac fibrosis was evaluated by Masson's trichrome staining.The expression of atrial natriuretic polypeptide (ANP) and brain natriuretic polypeptide (BNP) were determined by quantitative real time PCR (qRT-PCR). Western blot was applied to examine the expression of peroxisome proliferator-activated receptor gamma (PPARγ), PPARγ coactivator-1α (PGC-1α), fibrosisrelated and apoptosis-related proteins.Results: We found that CRP could significantly attenuate ISO-induced cardiac dysfunction, inhibit cardiac pathological hypertrophy and alleviate myocardial fibrosis and apoptosis. Mechanistically, the downregulation of PPARγ and PGC-1α in ISO-injected mice hearts and ISO-treated NRVMs could be reversed by CRP treatment. The beneficial effects of CRP against ISO-induced HF were abolished by PPARγ inhibitor (T0070907), suggesting that CRP-mediated PPARγ upregulation was essential for the preventive effect of CRP on ISO-induced cardiac dysfunction. Conclusions:In conclusion, our study demonstrated that CRP attenuates ISO-induced cardiac remodeling via PPARγ activation, which represents a new application for CRP in the prevention of chronic HF.

Background: Pathological cardiac hypertrophy is a major risk factor for cardiovascular diseases, including heart failure. However, limited pharmacological therapies are available for reversing the maladaptive process and restoring cardiac function. Citri reticulatae Pericarpium (CRP) has been used in traditional Chinese medicine prescriptions for clinical treatment. Previous studies have shown that CRP and its ingredients have beneficial effects on the cardiovascular system. However, whether CRP has a protective effect against pathological cardiac hypertrophy remains unknown.Methods: Primary neonatal rat cardiomyocytes (NRCMs) were treated with angiotensin II (Ang II) to induce pathological hypertrophy in vitro. Immunofluorescent staining and quantitative real-time PCR (qRT-PCR) were used to determine the cell size and the expression of hypertrophic gene markers (Anp and Bnp), respectively. Male C57BL/6 mice were subjected to the investigation of cardiac hypertrophy induced by Ang II (2.5 mg/kg/d for 4 weeks). CRP (0.5 g/kg/d for 4 weeks) was administrated to treat mice with or without peroxisome proliferatoractivated receptors gamma (PPARγ) inhibitor T0070907 (1 mg/kg/d for 4 weeks treatment) infused with Ang II.Cardiac hypertrophy (hematoxylin-eosin staining and qRT-PCR), fibrosis (Masson's Trichrome staining, qRT-PCR, and western blot), and cardiac function (echocardiography) were examined in these mice. Western blot was used to determine the protein level of PPARγ and PGC-1α both in NRCMs and in mice.Results: We found that CRP could prevent Ang II-induced pathological cardiac hypertrophy evidenced by improving cardiac function, decreasing hypertrophic growth and reducing cardiac fibrosis. Also, we demonstrated that PPARγ was upregulated by CRP both in NRCMs and in hearts. Moreover, PPARγ inhibitor could abolish the inhibitory effects of CRP on Ang II-induced pathological cardiac hypertrophy.Conclusions: CRP attenuates Ang II-induced pathological cardiac hypertrophy by activating PPARγ.