Vascular endothelial growth factor recovers suppressed cytochrome c oxidase activity by restoring copper availability in hypertrophic cardiomyocytes

Extensive mitochondrial proteome disturbance occurs during the early stages of acute myocardial ischemia

Mitochondrial malfunction leads to the remodeling of myocardial energy metabolism during myocardial ischemia (MI). However, the alterations to the mitochondrial proteome profile during this period has not yet been clarified. An acute MI model was established by high position ligation of the left anterior descending artery in 8-week-old C57BL/6N mice. After 15 min of ligation, the animals were euthanized, and their hearts were collected. The myocardial ultrastructure was observed using transmission electron microscopy (TEM). The cardiac mitochondrial proteome profile was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and bioinformatics analyses. TEM showed that the outer membrane of the mitochondria was dissolved, and the inner membrane (cristae) was corrupted and broken down extensively in the MI group. The mitochondrial membrane potential was decreased. More than 1,700 mitochondrial proteins were identified by LC-MS/MS analysis, and 119 were differentially expressed. Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis showed that endopeptidase activity regulation, the mitochondrial inner membrane, oxidative phosphorylation, the hypoxia-inducible factor-1 signaling pathway, the pentose phosphate pathway and the peroxisome proliferator-activated receptor signaling pathway were involved in the pathophysiological process in the early stage of acute MI. Extensive and substantial changes in the mitochondrial proteins as well as mitochondrial microstructural damage occur in the early stages of acute MI. In the present study, the series of proteins crucially involved in the pathways of mitochondrial dysfunction and metabolism were identified. Further studies are needed to clarify the roles of these proteins in myocardial metabolism remodeling during acute MI injury.

The role of targeted regulation of COX11 by miR-10a-3p in the development and progression of paediatric mycoplasma pneumoniae pneumonia

Background

MiR-10a-3p is associated with the pathogenesis of many immune inflammatory diseases including Mycoplasma pneumoniae pneumonia (MPP), and cytochrome coxidase assembly homologue 11 (COX11) is one of its direct target proteins. This study investigates the function and mechanism of miR-10a-3p targeting with COX11 in the development and progression of paediatric MPP.

Methods

Ninty-seven paediatric MPP patients and 100 age- and sex-matched healthy children were enrolled. Clinical and laboratory indicators of paediatric MPP patients were collected. The mRNA levels of the COX11 gene and miR-10a-3p were detected by qRT-PCR. THP-1 mononuclear macrophages were stimulated using MPP lipid-associated membrane proteins (Mp-LAMPs). The relative expression level of miR-10a-3p was detected after 12, 24, and 48 h. THP-1 cells were transfected to overexpress or inhibit the expression of miR-10a-3p, miR-10a-3p, COX11 mRNA, NF-κB signalling pathway-related proteins, and C-reactive protein (CRP) were detected after 48 h by Western blot.

Results

The relative expression level of miR-10a-3p in the MPP group was 2.38±0.52, compared with 1.76±0.38 in control group (t=4.584, P<0.001) whileCOX11 in MPP group was 3.70±1.12, compared to 5.78±1.84 in control group (t=4.876, P<0.001). Pearson correlation analysis showed that miR-10a-3p and COX11 in MPP group presented a negative correlation (r=-0.679, P<0.001). By searching in the prediction website of TargetScan database, it was found that miR-10a-3p and Cox11 genes had targeted regulatory binding sites, and the targeting relationship between miR-10a-3p and Cox11 genes was confirmed by dual luciferase reporting assay in 293T cells. Among paediatric MPP patients, miR-10a-3p expression had a positive correlation with the white blood cells count, erythrocyte sedimentation rate (ESR), and CRP expression, while COX11 mRNA expression had a positive correlation with ESR and CRP. After LAMP stimulation, the miR-10a-3p expression level in THP-1 cells significantly increased (P<0.05). After THP-1 cells were transfected with the miR-10a-3p mimic or inhibitor, the relative expression level of miR-10a-3p significantly increased or decreased, respectively. COX11 expression in the mimic group significantly decreased, whereas COX11 in the inhibitor group significantly increased (both P<0.05). In addition, after transfection, IκBα expression significantly decreased and that of p-IKKα/β, p-p65, and CRP significantly increased in the mimic group, and the opposite was true in the inhibitor group.

Conclusions

In paediatric MPP, increased miR-10a-3p downregulated COX11, activating NF-κB signalling pathway to promote disease development and progression.

Copper Preserves Vasculature Structure and Function by Protecting Endothelial Cells from Apoptosis in Ischemic Myocardium

The present study was undertaken to investigate whether Cu protects vasculatures from ischemic injury in the heart. C57/B6 mice were introduced to myocardial ischemia (MI) by permanent ligation of the left anterior descending (LAD) coronary artery. Two hours post-LAD ligation, mice were intravenously injected with a Cu-albumin (Cu-alb) solution, or saline as control. At 1, 4, or 7 days post-MI, hearts were collected for further analysis. A dramatic decrease in CD31-positive endothelial cells concomitantly with abundant apoptosis, along with obstruction of blood flow, was observed in ischemic myocardium 1 day post-MI. The early Cu-alb treatment protected CD31-positive cells from apoptosis, along with a preservation of micro-vessels and a decrease in infarct size. This early vasculature preservation ensured myocardial blood perfusion and protected cardiac contractile function until 28 days post-MI. This strategy of Cu-alb treatment immediately following MI would help develop a therapeutic approach for acute heart attack patients in a clinical setting.

Diisonitrile-Mediated Reactive Oxygen Species Accumulation Leads to Bacterial Growth Inhibition

The diisonitrile copper chelator SF2768 biosynthesized by Streptomyces thioluteus functions as a chalkophore that transports extracellular copper into producer cells in a complexed form. It was demonstrated that the treatment of eight bacteria, including Bacillus subtilis and Acinetobacter baumannii, with SF2768 led to a moderate growth inhibition which is associated with an increased level of reactive oxygen species (ROS). In addition, SF2768 and its diisonitrile analogues proved to be effective tyrosinase inhibitors. Three new analogues, SF2768 I, K, and L, were identified by detailed spectroscopic analysis.

Copper promotes migration of adipose-derived stem cells by enhancing vimentin-Ser39 phosphorylation

Mesenchymal stem cells (MSCs) are widely studied for their application in cell therapy. A noticed drawback of these cells in response to tissue injury is the low efficiency of homing. The present study was undertaken to explore a possible approach to promote the migration of MSCs. Primary cultures of rat adipose-derived stem cells (rADSCs) were cultured in standard L-DMEM media supplemented with or without copper (Cu) at its final concentration of 20 μM in cultures. The analyses of transwell and wound-healing assay revealed that Cu supplementation significantly promotes the migration of rADSCs in cultures. Further analysis found that Cu stimulated the phosphorylation of vimentin Ser39. Point mutation of vimentin Ser39 by substituting Ser with Ala prevented Cu-promoted migration of rADSCs. This study thus demonstrates that Cu promotes migration of rADSCs in cultures through at least in part Cu stimulation of vimentin Ser39 phosphorylation.

The Involvement of Cytochrome c Oxidase in Mitochondrial Fusion in Primary Cultures of Neonatal Rat Cardiomyocytes

Cytochrome c oxidase (CCO) is a copper-dependent enzyme of mitochondrial respiratory chain. In pressure overload-induced cardiac hypertrophy, copper level and CCO activity are both depressed, along with disturbance in mitochondrial fusion and fission dynamics. Copper repletion leads to recovery of CCO activity and normalized mitochondrial dynamics. The present study was undertaken to define the link between CCO activity and mitochondrial dynamic changes. Primary cultures of neonatal rat cardiomyocytes were treated with phenylephrine to induce cell hypertrophy. Hypertrophic cardiomyocytes were then treated with copper to reverse hypertrophy. In the hypertrophic cardiomyocytes, CCO activity was depressed and mitochondrial fusion was suppressed. Upon copper repletion, CCO activity was recovered and mitochondrial fusion was reestablished. Depression of CCO activity by siRNA targeting CCO assembly homolog 17 (COX17), a copper chaperone for CCO, led to fragmentation of mitochondria, which was not recoverable by copper supplementation. This study thus demonstrates that copper-dependent CCO is critical for mitochondrial fusion in the regression of cardiomyocyte hypertrophy.

The loss of copper is associated with the increase in copper metabolism MURR domain 1 in ischemic hearts of mice

The distribution of copper (Cu) in the biological system is regulated by Cu transporters and chaperones. It has been known for a long time that myocardial ischemia is accompanied by the loss of Cu from the heart, but the mechanism by which this occurs remains unknown. The present study was undertaken to understand the relationship between Cu loss and alterations in Cu transporters during the pathogenesis of myocardial ischemia. Male mice (C57 BL/6J) were subjected to left anterior descending (LAD) coronary artery ligation to induce myocardial ischemia. Changes in Cu concentrations in serum and hearts were determined from blood and tissue samples harvested at different time points for a total of 28 days after the operation. Cu concentrations in the ischemic myocardium were continuously decreased starting at the fourth day after LAD artery ligation, gradually depleted by more than 80% of the normal level at the 10th day, and remained at the lowest level (about 20% of normal levels) thereafter. Serum Cu concentrations were correspondingly increased starting at the fourth day, reached to the highest level between day 7 and 10, and gradually recovered to the normal level until 21st day after the operation. Along with the same time course, the intracellular Cu exporter copper metabolism MURR domain 1 (COMMD1) was significantly and sustainably increased, but ATP7A and ATP7B were not significantly changed in the ischemic myocardium. These results suggest that during the pathogenesis of myocardial ischemia, COMMD1 would play a critical role in exporting Cu from the ischemic myocardium to the blood. Impact statement In this work, we found that copper efflux from the ischemic heart leads to the elevation of serum copper concentrations, addressing a long-term question related to serum copper elevation in myocardial ischemia patients. The efflux of copper from the ischemic heart results at least in part from the upregulation of copper metabolism MURR domain 1 (COMMD1) in the heart upon ischemic insult. This work provides a novel insight into copper homeostasis and alteration in cardiovascular system.