Liraglutide promotes proliferation and migration of cardiac microvascular endothelial cells through PI3K/Akt and MAPK/ERK signaling pathways / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of liraglutide, an analogue of glucagon-like peptide-1, on the proliferation and migration of cardiac microvascular endothelial cells (CMECs) and explore the mechanism.</p><p><b>METHODS</b>In vitro cultured CMECs of SD rats were purified by differential adhesion method and identified immunocytochemically using CD31 antibody and factor VIII. MTT assay was performed to assess the proliferation of the first-generation cells exposed to different concentrations (0-1000 nm/L) of liraglutide. Western blotting was used to detect the activation of PI3K/Akt and MAPK/ERK signaling pathways. BrdU fluorescent labeling and scratch assay were performed to observe the proliferation and migration of CMECs following liraglutide treatment, and PI3K/Akt and MAPK/ERK pathway inhibitors LY294002 and PD98059, respectively, were used to further confirm the role of these signaling pathways in regulating the proliferation and migration of CMECs.</p><p><b>RESULTS</b>Immunocytochemical staining demonstrated a proportion of double positive cells exceeding 95%. The cells exhibited a logarithmic growth 48 h after plating. Liraglutide exposure concentration-dependently promoted the proliferation of CMECs with the optimal concentration of 100 nmol/L (P<0.05). Liraglutide exposure of the cells for 24 h significantly increased the levels of intracellular phosphorylated Akt and ERK (P<0.05), but pretreatment of the cells with Akt and ERK signaling pathway inhibitors 1 h before liraglutide obviously reversed such effect (P<0.05). BrdU and scratch assay showed that 100 nmol/L liraglutide significantly promoted the proliferation and migration of CMECs (P<0.05), but such effects were obviously suppressed by Akt and ERK inhibitors (P<0.05).</p><p><b>CONCLUSION</b>Liraglutide promotes the proliferation and migration of CMECs in vitro via PI3K/Akt and MAPK/ERK signaling pathways.</p>

Hepatocyte growth factor enhances protein synthesis in cardiomyocytes exposed to gamma-ray irradiation / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the protective effect of hepatocyte growth factor (HGF) on protein synthesis in rat cardiomyocytes exposed to gamma-ray irradiation.</p><p><b>METHODS</b>Primary cultured cardiomyocytes were irradiated with single-dose (20 Gy) gamma ray in the absence or presence of HGF (40 ng/ml) added in the cell culture 3 h before the exposure. Forty-eight hours after irradiation, the total cellular protein was measured and cell cycle analyzed by flow cytometry. The cardiomyoctes were also infected with AdGFP 48 h after irradiation and the fluorescence intensity of the green fluorescence protein (GFP) in the cells determined by flow cytometry 48 h after infection.</p><p><b>RESULTS</b>The protein synthesis was decreased significantly in the irradiated cardiomyocytes as compared with the control group (P<0.01), but was remedied significantly by incubation of the cells with HGF before the exposure (P<0.05). Flow cytometry revealed much lower mean fluorescence intensity (MFI) of GFP in irradiated cardiomycytes than in cells without the exposure (P<0.01); The MFI was higher in HGF-treated cardiomyocytes than in cells without HGF treatment following the exposure (P<0.01).</p><p><b>CONCLUSION</b>Gamma ray irradiation inhibits protein synthesis in cardiomyocytes, and HGF may attenuate this effect of gamma ray exposure for cardiomyocyte protection.</p>