LncRNA Fendrr inhibits hypoxia/reoxygenation-induced cardiomyocyte apoptosis by downregulating p53 expression
JOURNAL OF PHARMACY AND PHARMACOLOGY
Authors: Li, Xiang; Ni, Liangchun; Wang, Weixin; Zong, Liang; Yao, Bi
Abstract
Objective LncRNA Fendrr plays an important role in cardiac development, but its role in myocardial ischaemia-reperfusion (I/R) injury remains unclear. P53 has been shown to be an important regulator of apoptosis and is involved in myocardial I/R-induced apoptosis. This study aims at investigating whether Fendrr affects hypoxia/reoxygenation (H/R)-induced cardiomyocyte apoptosis through p53. Methods The left anterior descending coronary artery of the rat was ligated for 30 min and then reperfusion for 120 min by releasing the suture. Neonatal rat ventricular myocytes (NRVM) and rat cardiac cell line H9c2 were cultured for 6 h in hypoxia (95% N(2)and 5% CO2), followed by reoxygenation (95% air and 5% CO2) for 6 h. Transfection were performed in cells. Apoptosis was detected by flow cytometry. Moreover, RNA pull-down, RNA immunoprecipitation, ubiquitination assay, GST pull-down assay and co-immunoprecipitation were used to detect the regulation of Fendrr on p53 protein. Key findings Fendrr was decreased in I/R-induced myocardium and H/R-induced cardiomyocyte, and overexpression of Fendrr inhibited H/R-induced NRVM or H9c2 cells apoptosis. Further research found that the 1381-2100 nt of Fendrr bound to p53 protein and Fendrr promoted t direct binding of p53 to Cop1. The inhibition of Fendrr reduced the binding of E3 ubiquitin-protein ligase constitutive photomorphogenesis protein 1 (COP1) to p53 and reduced the ubiquitination of p53. Furthermore, the inhibition of Fendrr on H/R-induced NRVM or H9c2 cells apoptosis could be reversed by overexpression of p53. Conclusions Fendrr can inhibit H/R-induced cardiomyocyte apoptosis, which is partly through promoting the ubiquitination and degradation of p53 by increasing the binding of Cop1 and p53.
Effects of paralytic shellfish toxins on the middle intestine of Oncorhynchus mykiss: Glutathione metabolism, oxidative status, lysosomal function and ATP-binding cassette class C (ABCC) proteins activity
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
Authors: Painefilu, Julio C.; Bianchi, Virginia A.; Krock, Bernd; De Anna, Julieta S.; Kristoff, Gisela; Luquet, Carlos M.
Abstract
We studied the absorption, cytotoxicity and oxidative stress markers of Paralytic Shellfish Toxins (PST) from three extracts from Alexandrium catenella and A. ostenfeldii, in middle Oncorhynchus mykiss intestine in vitro and ex vivo preparations. We measured glutathione (GSH) content, glutathione-S transferase (GST), glutathione reductase (GR) and catalase (CAT) enzymatic activity, and lipid peroxidation in isolated epithelium exposed to 0.13 and 1.3 mu M PST. ROS production and lysosomal membrane stability (as neutral red retention time 50%, NRRT50) were analyzed in isolated enterocytes exposed to PST alone or plus 3 mu M of the ABCC transport inhibitor MK571. In addition, the concentration-dependent effects of PST on NRRT50 were assayed in a concentration range from 0 to 1.3 mu M PST. We studied the effects of three different PST extracts on the transport rate of the ABCC substrate DNP-SG by isolated epithelium. The extract with highest inhibition capacity was selected for studying polarized DNP-SG transport in everted and non-everted intestinal segments. We registered lower GSH content and GST activity, and higher GR activity, with no significant changes in CAT activity, lipid peroxidation or ROS level. PST exposure decreased NRRT50 in a concentration-depend manner (IC50 = 0.0045 mu M), but PST effects were not augmented by addition of MK571. All the three PST extracts inhibited ABCC transport activity, but this inhibition was effective only when the toxins were applied to the apical side of the intestine and DNP-SG transport was measured at the basolateral side. Our results indicate that PST are absorbed by the enterocytes from the intestine lumen. Inside the enterocytes, these toxins decrease GSH content and inhibit the basolateral ABCC transporters affecting the normal functions of the cell. Furthermore, PST produce a strong cytotoxic effect to the enterocytes by damaging the lysosomal membrane, even at low, non-neumtoxic concentrations.