BRD7 mediates hyperglycaemia‐induced myocardial apoptosis via endoplasmic reticulum stress signalling pathway

Bromodomain‐containing protein 7 (BRD7) is a tumour suppressor that is known to regulate many pathological processes including cell growth, apoptosis and cell cycle. Endoplasmic reticulum (ER) stress‐induced apoptosis plays a key role in diabetic cardiomyopathy (DCM). However, the molecular mechanism of hyperglycaemia‐induced myocardial apoptosis is still unclear. We intended to determine the role of BRD7 in high glucose (HG)‐induced apoptosis of cardiomyocytes. In vivo, we established a type 1 diabetic rat model by injecting a high‐dose streptozotocin (STZ), and lentivirus‐mediated short hairpin RNA (shRNA) was used to inhibit BRD7 expression. Rats with DCM exhibited severe myocardial remodelling, fibrosis, left ventricular dysfunction and myocardial apoptosis. The expression of BRD7 was up‐regulated in the heart of diabetic rats, and inhibition of BRD7 had beneficial effects against diabetes‐induced heart damage. In vitro, H9c2 cardiomyoblasts was used to investigate the mechanism of BRD7 in HG‐induced apoptosis. Treating H9c2 cardiomyoblasts with HG elevated the level of BRD7 via activation of extracellular signal‐regulated kinase 1/2 (ERK1/2) and increased ER stress‐induced apoptosis by detecting spliced/active X‐box binding protein 1 (XBP‐1s) and C/EBP homologous protein (CHOP). Furthermore, down‐regulation of BRD7 attenuated HG‐induced expression of CHOP via inhibiting nuclear translocation of XBP‐1s without affecting the total expression of XBP‐1s. In conclusion, inhibition of BRD7 appeared to protect against hyperglycaemia‐induced cardiomyocyte apoptosis by inhibiting ER stress signalling pathway.     

RPW8 promoter is involved in pathogen‐And stress‐inducible expression from Vitis pseudoreticulata

Based on previous cloning of VpRPW8‐e, we obtained a 1,126 bp VpRPW8‐e promoter sequence in this study. A large number of TATA‐boxes, CAAT‐boxes, and other cis‐acting elements were predicted including light‐responsive elements, hormone‐responsive elements, stress‐responsive elements, and growth‐ and development‐associated elements within the promoter sequence. To further investigate the function of this promoter, we examined its activity in response to biotic and abiotic stress. The VpRPW8‐e promoter was strongly activated by Plasmopara viticola infection, and activation also occurred when the orientation of the promoter was reversed, although to a lesser extent. Deletion analysis showed that the ?1,126 to ?475 bp region of VpRPW8‐e promoter had high activity. A promoter fragment 5′ deleted to ?475 bp (P_?475) was activated in response to heat and cold stress, and even more strongly in response to Phytophthora capsici and salicylic acid (SA). Furthermore, Transgenic Nicotiana benthamiana were generated, VpRPW8‐e driven by P_?475 enhanced resistance to Ph. capsici in N. benthamiana. Based on these results, the ?475 bp region was deduced to be an indispensable part of the VpRPW8‐e promoter. VpRPW8‐e promoter is involved in pathogen‐ and stress‐inducible expression.