The HIF-1α transcriptional factor and the BH-3 only protein BNIP3 are known to play fundamental roles in response to hypoxia. The objective of this research is to investigate the molecular mechanisms and the correlation of HIF-1α, BNIP3 and IGFBP-3 in hypoxia-induced cardiomyocytes injuries. Heart-derived H9c2 cells and neonatal rat ventricular myocytes (NRVMs) were incubated in normoxic or hypoxic conditions. Hypoxia increased HIF-1α expression and activated the downstream BNIP3 and IGFBP-3 thereby triggered mitochondria-dependent apoptosis. Moreover, IGF1R/PI3K/Akt signaling was attenuated by HIF-1α-dependent IGFBP-3 expression to enhance hypoxia-induced apoptosis. Autophagy suppression with 3-methyladenine or siATG5 or siBeclin-1 significantly decreased myocardial apoptosis under hypoxia. Knockdown of FoxO3a or BNIP3 significantly abrogated hypoxia-induced autophagy and mitochondria-dependent apoptosis. Moreover, prolonged-hypoxia induced HIF-1α stimulated BNIP3 and enhanced IGFBP-3 activation to inhibit IGF1R/PI3K/Akt survival pathway and mediate mitochondria-dependent cardiomyocyte apoptosis. HIF-1α and FoxO3a blockage are sufficient to annul the change of excessive hypoxia of hearts.

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Dilated cardiomyopathy (DCM) is the most common form of non-ischemic cardiomyopathy. It is characterized by ventricular chamber dilation, and myocyte hypertrophy. Human tumorous imaginal disc 1 (Tid1), a chaperone protein and response to regulate number of signaling molecules in the mitochondria or cytosol. Tid1 also plays a major role in preventing DCM; however, the role of Tid1 in isoproterenol (ISO)-induced cardiac apoptosis and hypertrophy remains unclear. H9c2 cells were pretreated Tid1 before ISO-induced hypertrophy and apoptosis and then evaluated by IHC, TUNEL assay, IFC, Co-IP, and Western blot. From the IHC experiment, we found that Tid1 proteins were increased in tissues from different stages of human myocardial infarction. Using H9c2 cardiomyoblast cells we found that Tid1 was decreased by ISO treatment. However, over-expression of Tid1S suppressed NFATc3, BNP and calcineurin protein expression and inhibited NFATc3 nuclear translocation in ISO induced cardiomyoblast cells. On the other hand, Tid1S over-expression activated survival proteins p-AKTser473 and decreased caspase-3 and cytochrome c expression. We also found that overexpression of Tid1 enhanced CHIP expression, and induced CHIP to ubiquitinate Gαs, resulting in increased Gαs degradation. Our study showed that Gαs is a novel substrate of CHIP, and we also found that the Tid1-CHIP complex plays an essential role in inhibiting ISO induced cardiomyoblast hypertrophy and apoptosis.

This study shows that the ECM degradation-associated pathway, including uPA and tPA and the downstream MMP-2/-9 protein, was significantly suppressed in HA22T cells treated with a Zanthoxylum avicennae extract (YBBE). The endogenous inhibitors, including TIMP-1/-2 and PAI-1, were enhanced in HA22T cells by the YBBE treatment. The expression of MMP-2/-9 and TIMP-1/-2 was respectively assessed by using RT-PCR and a zymography assay. The mRNA levels and enzymatic activity of MMP-2/-9 were down-regulated by the YBBE treatment in a dose-dependent manner, while the TIMP-1/-2 levels were conversely markedly increased. The PP2A siRNA or PP2A inhibitor totally reversed the YBBE effects, confirming the essential role of PP2A in YBBE inhibiting the HA22T cell migration and invasion effects. Xenografted animal experiments on nude mice demonstrated similiar results to the in vitro system. Both the in vitro and in vivo models clearly demonstrate that YBBE inhibited the highly metastatic HA22T liver cancer cell migration and invasion effects through PP2A activation.

ObjectivesOxidized low-density lipoproteins (oxLDL) and oxidized low-density lipoprotein autoantibodies (OLAB) have been detected in human plasma and atherosclerotic lesions. OLAB appear to play a role in the clearance of oxLDL from circulation. Higher levels of OLAB appear to be associated with a reduced risk of a wide range of cardiovascular diseases. We investigated the prognostic value of plasma oxLDL and OLAB in patients undergoing primary coronary balloon angioplasty for acute ST-elevation myocardial infarction (STEMI).MethodsPlasma oxLDL and OLAB concentrations were measured in 56 patients with acute STEMI before primary angioplasty, and then 3 days, 7 days and 1 month after the acute event. Follow-up angiography was repeated 6 months later to detect the presence of restensosis (defined as >50% luminal diameter stenosis). The thrombolysis in myocardial infarction (TIMI) risk score was calculated to determine the relationship between OLAB/oxLDL ratio and TIMI risk scores.ResultsOf the 56 patients, 18 (31%) had angiographic evidence of restenosis. Plasma OLAB concentrations were significantly lower in the restenosis group before angioplasty (181±114 vs. 335±257 U/L, p = 0.003), and at day 3 (155±92 vs. 277±185 U/L, p<0.001) and day 7 (177±110 vs. 352±279 U/L, p<0.001) after the acute event. There was no difference in oxLDL concentration between the two groups. The ratio of OLAB/oxLDL positively correlated with TIMI risk scores before angioplasty (p for trend analysis, p = 0.004), at day 3 (p = 0.008) and day 7 (p<0.001) after STEMI.SignificanceA relative deficit of OLAB, and hence likely impaired clearance of oxLDL, is associated with the risk of arterial restenosis after primary angioplasty for acute STEMI.