Inhibition of DRP1-dependent mitochondrial fission by Mdivi-1 alleviates atherosclerosis through the modulation of M1 polarization.

BACKGROUND: Inflammation and immune dysfunction with classically activated macrophages(M1) infiltration are important mechanisms in the progression of atherosclerosis (AS). Dynamin-related protein 1 (DRP1)-dependent mitochondrial fission is a novel target for alleviating inflammatory diseases. This study aimed to investigate the effects of DRP1 inhibitor Mdivi-1 on AS. METHODS: ApoE-/- mice were fed with a high-fat diet supplemented with or without Mdivi-1. RAW264.7 cells were stimulated by ox-LDL, pretreated with or without MCC950, Mito-TEMPO, or Mdivi-1. The burden of plaques and foam cell formation were determined using ORO staining. The blood lipid profles and inflammatory cytokines in serum were detected by commercial kits and ELISA, respectively. The mRNA expression of macrophage polarization markers, activation of NLRP3 and the phosphorylation state of DRP1 were detected. Mitochondrial reactive oxygen species (mito-ROS), mitochondrial staining, ATP level and mitochondrial membrane potential were detected by mito-SOX, MitoTracker, ATP determination kit and JC-1 staining, respectively. RESULTS: In vivo, Mdivi-1 reduced the plaque areas, M1 polarization, NLRP3 activation and DRP1 phosphorylation at Ser616. In vitro, oxidized low-density lipoprotein (ox-LDL) triggered M1 polarization, NLRP3 activation and abnormal accumulation of mito-ROS. MCC950 and Mito-TEMPO suppressed M1 polarization mediated foam cell formation. Mito-TEMPO significantly inhibited NLRP3 activation. In addition, Mdivi-1 reduced foam cells by inhibiting M1 polarization. The possible mechanisms responsible for the anti-atherosclerotic effects of Mdivi-1 on reducing M1 polarization were associated with suppressing mito-ROS/NLRP3 pathway by inhibiting DRP1 mediated mitochondrial fission. In vitro, similar results were observed by DRP1 knockdown. CONCLUSION: Inhibition of DRP1-dependent mitochondrial fission by Mdivi-1 alleviated atherogenesis via suppressing mito-ROS/NLRP3-mediated M1 polarization, indicating DRP1-dependent mitochondrial fission as a potential therapeutic target for AS.

Suppression of NHE1 by small interfering RNA inhibits HIF-1α-induced angiogenesis in vitro via modulation of calpain activity.

Hypoxia-inducible factor-1 (HIF-1) orchestrates angiogenesis under hypoxic conditions mainly due to increased expression of such target genes as vascular endothelial growth factor (VEGF). Na+/H+exchanger-1 (NHE1), a potential HIF target gene product, plays a pivotal role in proliferation, survival, migration, adhesion and so on. However, it is unknown whether NHE1 is involved in HIF-1α-induced angiogenesis. This present study demonstrated that the expression of NHE1 was much higher in human umbilical vein endothelial cells (HUVECs) infected with adenovirus encoding HIF-1α (rAd-HIF) than with vacuum adenovirus (vAd). HIF-1α also increased the expression of VEGF, the expression and activity of calpains, and the intracellular pH. Moreover, small interfering RNA targeting NHE1 (NHE1 siRNA) dramatically decreased the expression of NHE1 and thus lowered the intracellular pH, and it also attenuated the protein expression of calpain-2 but not calpain-1, resulting in the lower calpain activity. Furthermore, HIF-1α enhanced the proliferation, migration and Matrigel tube formation, which were inhibited by NHE1 siRNA. Finally, the inhibitory effect of NHE1 siRNA was reversed by VEGF and the reversibility of the later was abrogated by the calpain inhibitor ALLM. In conclusion, the findings have revealed that NHE1 might participate in HIF-1-induced angiogenesis due, at least in part, to the alteration of the calpain activity, suggesting that NHE1 as well as calpains might represent a potential target of controlling angiogenesis in response to the hypoxic stress under various pathological conditions.

Experimental research of RB94 gene transfection into retinoblastoma cells using ultrasound-targeted microbubble destruction.

The purpose of this study was to explore the transfection of the recombinant expression plasmid pEGFP-C1/RB94 into human retinoblastoma cells (HXO-Rb44) using ultrasound-targeted microbubble destruction (UTMD). pEGFP-C1/RB94 was transfected into HXO-Rb44 in vitro by UTMD, with liposome as the positive control. After 24 to 72 h, the expression of the reporter gene enhanced green fluorescent protein (EGFP) was observed using fluorescent microscopy and flow cytometry. The cell viability of HXO-Rb44 was measured by a MTT assay. The mRNA and proteins of RB94, caspase-3 and Bax were analyzed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Moreover, the apoptosis rate and cell cycle progression of the cells were detected by flow cytometry. This study demonstrated that UTMD can enhance the transfection efficiency of RB94, which has an obvious impact on the inhibition of the growth process of retinoblastoma cells, suggesting that the combination of UTMD and RB94 compounds might be a useful tool for use in the gene therapy of retinoblastoma.