Low-intensity laser irradiation at 660 nm stimulates transcription of genes involved in the electron transport chain.

BACKGROUND DATA: Low-intensity laser irradiation (LILI) has been shown to stimulate cellular functions leading to increased adenosine triphosphate (ATP) synthesis. This study was undertaken to evaluate the effect of LILI on genes involved in the mitochondrial electron transport chain (ETC, complexes I-IV) and oxidative phosphorylation (ATP synthase). METHODS: Four human skin fibroblast cell models were used in this study: normal non-irradiated cells were used as controls while wounded, diabetic wounded, and ischemic cells were irradiated. Cells were irradiated with a 660 nm diode laser with a fluence of 5 J/cm(2) and gene expression determined by quantitative real-time reverse transcription (RT) polymerase chain reaction (PCR). RESULTS: LILI upregulated cytochrome c oxidase subunit VIb polypeptide 2 (COX6B2), cytochrome c oxidase subunit VIc (COX6C), and pyrophosphatase (inorganic) 1 (PPA1) in diabetic wounded cells; COX6C, ATP synthase, H+transporting, mitochondrial Fo complex, subunit B1 (ATP5F1), nicotinamide adenine dinucleotide (NADH) dehydrogenase (ubiquinone) 1 alpha subcomplex, 11 (NDUFA11), and NADH dehydrogenase (ubiquinone) Fe-S protein 7 (NDUFS7) in wounded cells; and ATPase, H+/K+ exchanging, beta polypeptide (ATP4B), and ATP synthase, H+ transporting, mitochondrial Fo complex, subunit C2 (subunit 9) (ATP5G2) in ischemic cells. CONCLUSIONS: LILI at 660 nm stimulates the upregulation of genes coding for subunits of enzymes involved in complexes I and IV and ATP synthase.

MicroRNA-155 inhibits proliferation and migration of human extravillous trophoblast derived HTR-8/SVneo cells via down-regulating cyclin D1.

MiR-155 is known to participate in various cellular processes by targeting gene expression. We previously revealed a link between miR-155 and perturbation of trophoblast invasion and differentiation. This study aimed to investigate the target molecule(s) of miR-155 on the influence on the proliferation and migration of trophoblast cells. Bioinformatics analysis showed that, at the 3' untranslated region (UTR) of cyclin D1, six bases are complementary to the seed region of miR-155. Luciferase assays and cyclin D1 3'UTR transfection assays validated that cyclin D1 3'UTR was the target of miR-155 in HTR-8/SVneo cells. Overexpression of miR-155 in HTR-8/SVneo cells reduced the level of cyclin D1 protein, decreased cell proliferation and invasion, and increased cell number at the G1 stage. Furthermore, the increased expression of miR-155 also regulated the protein levels of kinase inhibitory protein p27 and phosphorylated cytoskeletal protein filamin A. In conclusion, we found that cyclin D1 may be a target of miR-155 in HTR-8/SVneo cells, and demonstrated a negative regulatory role of miR-155 involved in cyclin D1/p27 pathway in proliferation and migration of the cells.

Analysis of the assembly profiles for mitochondrial- and nuclear-DNA-encoded subunits into complex I.

Complex I of the respiratory chain is composed of at least 45 subunits that assemble together at the mitochondrial inner membrane. Defects in human complex I result in energy generation disorders and are also implicated in Parkinson's disease and altered apoptotic signaling. The assembly of this complex is poorly understood and is complicated by its large size and its regulation by two genomes, with seven subunits encoded by mitochondrial DNA (mtDNA) and the remainder encoded by nuclear genes. Here we analyzed the assembly of a number of mtDNA- and nuclear-gene-encoded subunits into complex I. We found that mtDNA-encoded subunits first assemble into intermediate complexes and require significant chase times for their integration into the holoenzyme. In contrast, a set of newly imported nuclear-gene-encoded subunits integrate with preexisting complex I subunits to form intermediates and/or the fully assembly holoenzyme. One of the intermediate complexes represents a subassembly associated with the chaperone B17.2L. By using isolated patient mitochondria, we show that this subassembly is a productive intermediate in complex I assembly since import of the missing subunit restores complex I assembly. Our studies point to a mechanism of complex I biogenesis involving two complementary processes, (i) synthesis of mtDNA-encoded subunits to seed de novo assembly and (ii) exchange of preexisting subunits with newly imported ones to maintain complex I homeostasis. Subunit exchange may also act as an efficient mechanism to prevent the accumulation of oxidatively damaged subunits that would otherwise be detrimental to mitochondrial oxidative phosphorylation and have the potential to cause disease.

Nuclear-encoded mitochondrial complex I gene expression is restored to normal levels by inhibition of unedited ATP9 transgene expression in Arabidopsis thaliana.

Mitochondria play an important role during sporogenesis in plants. The steady state levels of the nuclear-encoded mitochondrial complex I (nCI), PSST, TYKY and NADHBP transcripts increase in flowers of male-sterile plants with impairment of mitochondrial function generated by the expression of the unedited version of ATP9 (u-ATP9). This suggests a nuclear control of nCI genes in response to the mitochondrial flaw. To evaluate this hypothesis, transgenic plants carrying the GUS reporter gene, under the control of the PSST, TYKY and NADHBP promoters, were constructed. We present evidence that suppression by antisense strategy of the expression of u-ATP9 restores the normal levels of three nCI transcripts, indicating that the increase in PSST, TYKY and NADHBP in plants with a mitochondrial flaw occurs at the transcriptional level. The data presented here support the hypothesis that a mitochondrial dysfunction triggers a retrograde signaling which induce some nuclear-encoded mitochondrial genes. Moreover, these results demonstrate that this is a valuable experimental model for studying nucleus-mitochondria cross-talk events.

High-frequency stimulation of both zona incerta and subthalamic nucleus induces a similar normalization of basal ganglia metabolic activity in experimental parkinsonism.

High-frequency stimulation (HFS) of the subthalamic nucleus (STN) alleviates dramatically motor symptoms in Parkinson's disease, and recently it has been suggested that zona incerta (ZI) stimulation might be as beneficial to patients. We used in situ cytochrome oxidase (CoI) mRNA hybridization to investigate and compare the effects of HFS of the STN and the ZI on metabolic activity of the STN, globus pallidus (GP), and substantia nigra reticulata (SNr) in normal rats as well as in rats with 6-hydroxydopamine (6-OHDA) lesion, an animal model of Parkinson's disease. In normal rats, HFS of the STN, as well as of the ZI, induced a significant decrease in CoI mRNA expression within the STN and SNr but an increase within the GP. In 6-OHDA rats, HFS of the STN reversed dopamine denervation-induced changes in the expression of CoI mRNA in the STN, SNr, and GP. Similar results were obtained with HFS of the ZI except for the STN, which showed only a trend toward normalization. These data suggest that the ZI, as well as the STN, are implicated in the functional mechanism of HFS supporting the involvement of GABA transmission for the reduction of neuronal activity in the basal ganglia output structures.