Protective effects of TREK-1 against oxidative injury induced by SNP and H2O2

Neuroprotective Effect of Low-Intensity Pulsed Ultrasound Against MPP+-Induced Neurotoxicity in PC12 Cells: Involvement of K2P Channels and Stretch-Activated Ion Channels

Parkinson's disease is the second most common neurodegenerative disease. It is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. 1-Methyl-4-phenylpyridinium (MPP⁺) is a dopaminergic neuronal toxin that is widely used in constructing Parkinson's disease models in vitro. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapeutic approach that has neuromodulation and neuroprotective effects in the central neural system; however, whether LIPUS can provide protection for dopaminergic neurons against MPP⁺-induced neurocytotoxicity remains unknown. In this study, we found that pre-treatment with LIPUS (1 MHz, 50 mW/cm², 20% duty cycle and 100-Hz pulse repetition frequency, 10 min) inhibited MPP⁺-induced neurotoxicity and mitochondrial dysfunction in PC12 cells. LIPUS decreased MPP⁺-induced oxidative stress by modulating antioxidant proteins, including thioredoxin-1 and heme oxygenase-1, and prevented neurocytotoxicity via the phosphoinositide 3-kinase (PI3K)-Akt and ERK1/2 pathways. Furthermore, these beneficial effects were attributed to the activation of K2P channels and stretch-activated ion channels by LIPUS. These data indicate that LIPUS protects neuronal cells from MPP⁺-induced cell death through the K2P channel- and stretch-activated ion channel-mediated downstream pathways. The data also suggest that LIPUS could be a promising therapeutic method in halting or retarding the degeneration of dopaminergic neurons in Parkinson's disease in a non-invasive manner.

Transcriptome profiling of 3D co-cultured cardiomyocytes and endothelial cells under oxidative stress using a photocrosslinkable hydrogel system

Myocardial infarction (MI) is one of the most common among cardiovascular diseases. Endothelial cells (ECs) are considered to have protective effects on cardiomyocytes (CMs) under stress conditions such as MI; however, the paracrine CM-EC crosstalk and the resulting endogenous cellular responses that could contribute to this protective effect are not thoroughly investigated. Here we created biomimetic synthetic tissues containing CMs and human induced pluripotent stem cell (hiPSC)-derived ECs (iECs), which showed improved cell survival compared to single cultures under conditions mimicking the aftermath of MI, and performed high-throughput RNA-sequencing to identify target pathways that could govern CM-iEC crosstalk and the resulting improvement in cell viability. Our results showed that single cultured CMs had different gene expression profiles compared to CMs co-cultured with iECs. More importantly, this gene expression profile was preserved in response to oxidative stress in co-cultured CMs while single cultured CMs showed a significantly different gene expression pattern under stress, suggesting a stabilizing effect of iECs on CMs under oxidative stress conditions. Furthermore, we have validated the in vivo relevance of our engineered model tissues by comparing the changes in the expression levels of several key genes of the encapsulated CMs and iECs with in vivo rat MI model data and clinical data, respectively. We conclude that iECs have protective effects on CMs under oxidative stress through stabilizing mitochondrial complexes, suppressing oxidative phosphorylation pathway and activating pathways such as the drug metabolism-cytochrome P450 pathway, Rap1 signaling pathway, and adrenergic signaling in cardiomyocytes pathway.

STATEMENT OF SIGNIFICANCE

Heart diseases are the leading cause of death worldwide. Oxidative stress is a common unwanted outcome that especially occurs due to the reperfusion following heart attack or heart surgery. Standard methods of in vivo analysis do not allow dissecting various intermingled parameters, while regular 2D cell culture approaches often fail to provide a biomimetic environment for the physiologically relevant cellular phenotypes. In this research, a systematic genome-wide transcriptome profiling was performed on myocardial cells in a biomimetic 3D hydrogel-based synthetic model tissue, for identifying possible target genes and pathways as protecting regulators against oxidative stress. Identification of such pathways would be very valuable for new strategies during heart disease treatment by reducing the cellular damage due to reperfusion injury.

Functional study of TREK-1 potassium channels during rat heart development and cardiac ischemia using RNAi techniques

To explore the physiological and pathological significance of the 2-pore domain potassium channel TWIK-related K(+) (TREK)-1 in rat heart, its expression and role during heart development and cardiac ischemia were investigated. In the former study, the ventricles of Sprague Dawley rats were collected from embryo day 19 to postnatal 18 months and examined for mRNA and protein expression of TREK-1. It was found that both increased during development, reached a maximum at postnatal day 28, and remained higher at postnatal day 3 through to postnatal 18 months. In the latter study, protein expression of TREK-1 was examined after initiation of acute heart ischemia by ligation of the left anterior descending coronary artery. TREK-1 expression was found to be increased in the endocardium but unchanged in the epicardium. In primary cultured rat neonatal ventricular myocytes subjected to hypoxia (oxygen-glucose deprivation), TREK-1 expression was increased. In cultured neonatal cardiomyocytes, silencing of the TREK-1 gene by lentivirus delivery of the short-hairpin RNAs, L-sh-492 and L-sh-605, was found to promote their viability and number. In addition, both short-hairpin RNA provided protection against hypoxia-induced injury to cardiomyocytes in vitro. These results suggest that TREK-1 plays an important role in neonatal rat heart development and downregulation of TREK-1 may provide protection against ischemic injury. It seems that TREK-1 is a potential drug target for treatment of acute heart ischemia.

Fullerene-C60/liposome complex: Defensive effects against UVA-induced damages in skin structure, nucleus and collagen type I/IV fibrils, and the permeability into human skin tissue

We previously reported biological safety of fullerene-C60 (C60) incorporated in liposome consisting of hydrogenated lecithin and glycine soja sterol, as Liposome-Fullerene (0.5% aqueous phase; a particle size, 76nm; Lpsm-Flln), and its cytoprotective activity against UVA. In the present study, Lpsm-Flln was administered on the surface of three-dimensional human skin tissue model, rinsed out before each UVA-irradiation at 4 J/cm(2), and thereafter added again, followed by 19-cycle-repetition for 4 days (sum: 76 J/cm(2)). UVA-caused corneum scaling and disruption of epidermis layer were detected by scanning electron microscopy. Breakdown of collagen type I/IV, DNA strand cleavage and pycnosis/karyorrhexis were observed in vertical cross-sections of UVA-irradiated skin models visualized with fluorescent immunostain or Hoechst 33342 stain. These skin damages were scarcely repressed by liposome alone, but appreciably repressed by Lpsm-Flln of 250 ppm, containing 0.75 ppm of C60-equivalent to a 1/3300-weight amount vs. the whole liposome. Upon administration with Lpsm-Flln [16.7 microM (12 ppm): C60-equivalent] on human abdomen skin biopsies mounted in Franz diffusion cells, C60 permeated after 24h into the epidermis at 1.86 nmol/g tissue (1.34 ppm), corresponding to 0.3% of the applied amount and a 9.0-fold dilution rate, but C60 was not detected in the dermis by HPLC, suggesting no necessity for considering a toxicity of C60 due to systemic circulation via dermal veins. Thus Lpsm-Flln has a potential to be safely utilized as a cosmetic anti-oxidative ingredient for UVA-protection.