DRAM1 blocking peptide

Background: DRAM1 (Damage-regulated autophagy modulator 1) was reported as one of the most important lysosome membrane protein that mediates the interaction between autophagosome and lysosome. Our aim was to investigate whether DRAM1 contributes to cardiac remodeling after acute myocardial infarction (AMI) and the underlying mechanisms. Methods and results: Adenovirus harboring DRAM1 was injected in the peri-infarct zone in a rat model of AMI experimentally produced by permanent ligation of left anterior descending (LAD) coronary artery. Increased DRAM1 expression protected the cardiomyocytes from ischemia stress-induced autophagy flux obstacle and improved cardiac prognosis after AMI. DRAM1 overexpression attenuated the accumulation of autophagy substrate protein, LC3IIand p62/SQSTM1 obviously both in vivo and in vitro. An adenovirus harboring mRFP-GFP-LC3 showed that DRAM1 overexpression restored the autophagic flux by enhancing autophagosome conversion to autophagolysosome. Although Atg12 mRNA was up-regulated with DRAM1 overexpression the free Atg12 protein was decreased accompanied by increased Atg12-Atg5 conjugate both in vitro and in vivo. Of interest, immunoprecipitation assay showed that DRAM1 interacted with Atg7, but without direct interaction with Atg5 or Atg12. Notably, the effect of DRAM1 on autophagy flux and cardiomyocyte protection could be mitigated by Atg7 siRNA. Conclusions: Our results indicated that DRAM1 protected cardiomyocytes from ischemia stress-induced autophagy flux obstacle and uncovered a novel DRAM1-Atg7-Atg12/Atg5 autophagy flux regulation pathway under conditions of myocardial ischemic stress.

L-arginine has been demonstrated to stimulate cell proliferation and prevent LPS-induced death of intestinal cell. To identify genes responsed to arginine treatment in intestinal cell, gene expression profiles were analyzed using high-density oligonucleotide microarray in porcine intestinal epithelial cells (IPEC-1) treated with 100 (control) or 350 mu M arginine. Results showed that expression levels of 306 genes were up-regulated and 280 genes down-regulated in IPEC-1 cultured in medium containing 350 mu M arginine compared with that of the control. Although the biochemical functions of some genes had not previously been defined, we were able to identify some up-regulated genes that are known to play important roles in transportion (e.g. ATP6V1G2, SLC9A4), metabolism (e.g. AKRIC4, GHRL). transcription and signal transduction (e.g. PTGFR, OCT2), signaling and proliferation (e.g. UPTI, FGFR1). cell cycle and apoptosis (e.g. DRAM1. GADD45A), cytoskeletal and cell adhesion (e.g. DNMBP, ITGB2) and immune response (e.g. OAS1, IL15), and some down-regulated genes that are related to transportion and metabolism (e.g. SLC25A25, COX I). cytoskeletal and cell adhesion (e.g. PROC, COL1OA1) and immune response (e.g. SLA-DMA, CD80). The RT-PCR analysis demonstrated that 350 mu M arginine treatment increased ITGB (109%), AKRIC4 (367%), ATP6VIG2 (196%), DRAMI (88%), GHRL (243%) and SLC9A2 (138%). which were almost consistent with the data obtained from the microarray analysis. Our findings provided a molecular mechanism to explain cytoprotective effects of arginine and laid the foundation for future research on cellular mechanisms of arginine regulating cell growth and proliferation.