e0003 Cardiac-specific expression of E3 ligase Nrdp1 increases ischaemia and reperfusion-induced cardiac injury in transgenic mice

Abstract

Objective To investigate the influences of high trans fatty acids (TFA) intake on fatty-acid constitution ratios of erythrocyte membrane in rabbits. Method 32 New Zealand white rabbits were randomly divided into four groups: control group with common feed; high TFA group with additional TFA 5.0 g/kg.d; high-fat (HF) group with high cholesterol feed and TFA+HF group. The erythrocyte membranes were prepared at 0, 4, 8, 12 weeks. Two kinds of saturated FA (C18:0 and C16:0), four kinds of unsaturated FA (C18:1, C18:2, C20:4, C20:5 and total uÀ3) and two kinds of TFA (t-C18:1 and t-C16:1) in erythrocyte membrane were determined with gas chroma. Four constitution ratios of C18:1/C18:0, C18:1/t-C18:1, uÀ3/+TFA and uÀ3/C18:0 were calculated.Results Compared with the control group, TFA group showed not only obviously higher constitution ratios of TFA, but obviously higher ratios of saturated FA and lower ratios of polyunsaturated FA, especially uÀ3 FA (2.3860.35 vs 3.2860.48, p<0.05), in erythrocyte membrane. The abnormality of constitution ratios of unsaturated FA and polyunsaturated FA in TFA were similar to that in HF group. More abnormal changes of erythrocyte membrane FA constitution ratios were showed in TFA+HF group. Conclusions High TFA intake could increase the constitution ratios of TFA and saturated fatty acids, but decrease polyunsaturated fatty acids, especially uÀ3 fatty acids, in erythrocyte membrane. These effects were equivalent with the effects of high cholesterol intake. Combined with TFA and high cholesterol intake had obviously synergistic effects. Aim TLR-4 has been proved to take part in MIRI of heart. But the researches mostly focused on the relationship between TLR-4 and global heart dysfunction or cadiocyte apoptosis. The effect of TLR-4 on CMECs which are the most important component in MIRI is not clear. To explore the change of TLR-4 signal pathoway during hypoxiaereoxygenation (H-R) of cardiac microvascular endothelial cells (CMECs) injury. Methods The CMECs were isolated from the hearts of adult rats. The obtained CMECs were exposed to hypoxia (940 ml/l N 2 , 50 ml/ l CO 2 and 10 ml/l O 2 ) for 6 h, following by reoxygenation (950 ml/l air, 50 ml/l CO 2 ) for 2 h, 12 h or 24 h. The proliferation of CMECs was assessed by MTT colourimetry. TLR-4 and NF-kB expressions were analysed by Western blot. The levels of IL-6 and TNF-a were detected by ELISA. Results The proliferation ability of CMECs was significantly inhibited by H-R injury (p<0.01). H-R injury increased TLR-4 expression after 2 h or 12 h reoxygenation (p<0.05). Objective Neuregulin receptor degradation protein-1 (Nrdp1) is an E3 ubiquitin ligase that regulates the proteasomal degradation and activity of proteins involved in cell growth, inflammation and apoptosis, including ErbB3, BRUCE, MyD88 and TBK1. However, the effect of Nrdp1 on cardiac ischaemia/reperfusion (I/R) injury in vivo has not yet been investigated. Methods and resultsWe generated transgenic mice with cardiacspecific overexpression of Nrdp1 using a-myosin heavy chain...