CYP1A1 is a target of miR-892a-mediated post-transcriptional repression.

Cytochrome P450 1A1 (CYP1A1) is a member of the cytochrome p450 enzyme family, which is involved in the metabolisms of carcinogenic metabolites, such as benzo(a)pyrene. In this study, we identified miR-892a as a negative regulator of CYP1A1 expression. Luciferase assays revealed a sequence in the 3'-untranslated region of CYP1A1 that displayed a perfect match with miR-892a, and revealed that this sequence was a specific miR-892a target site. The overexpression of miR­892a inhibited the expression of the CYP1A1 protein, and the miR­892a antagonist increased CYP1A1 expression. Of note, benzo(a)pyrene, a major inducer of CYP1A1 transcription, decreased the expression of miR-892a. Moreover, the miR-892a-induced CYP1A1 repression inhibited the benzo(a)pyrene-mediated decrease in cell viability. These data provide insight into the CYP1A1 regulatory network.

Resveratrol alters microRNA expression profiles in A549 human non-small cell lung cancer cells.

Resveratrol is a plant phenolic phytoalexin that has been reported to have antitumor properties in several types of cancers. In particular, several studies have suggested that resveratrol exerts antiproliferative effects against A549 human non-small cell lung cancer cells; however, its mechanism of action remains incompletely understood. Deregulation of microRNAs (miRNAs), a class of small, noncoding, regulatory RNA molecules involved in gene expression, is strongly correlated with lung cancer. In this study, we demonstrated that resveratrol treatment altered miRNA expression in A549 cells. Using microarray analysis, we identified 71 miRNAs exhibiting greater than 2-fold expression changes in resveratrol-treated cells relative to their expression levels in untreated cells. Furthermore, we identified target genes related to apoptosis, cell cycle regulation, cell proliferation, and differentiation using a miRNA target-prediction program. In conclusion, our data demonstrate that resveratrol induces considerable changes in the miRNA expression profiles of A549 cells, suggesting a novel approach for studying the anticancer mechanisms of resveratrol.

MicroRNAs that respond to histone deacetylase inhibitor SAHA and p53 in HCT116 human colon carcinoma cells.

MicroRNAs (miRNAs) are important post-transcriptional regulators involved in many biological processes. We investigated the expression profiles of miRNAs affected by the histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), and p53 in the human colon cancer cell line, HCT116 (wt-p53) and its derivative, HCT116 (null-p53). In a microarray assay, 144 of 275 human miRNAs showed several-fold changes in transcription. Most of these miRNAs were strongly affected by SAHA, and their expression profiles varied depending on the presence of p53. Thirty-one miRNAs showing the greatest expression changes were selected for target prediction, and genes related to apoptosis (102), cell cycle (38), and differentiation (102) were predicted. Each miRNA had many target genes, and several genes also were targeted by many miRNAs. Putative p53 upstream binding sites for the miRNAs were determined, and most sites scored >85%, suggesting a high probability of binding. In conclusion, we identified several miRNAs whose expression was affected by both SAHA and p53. Many of the miRNAs showed dramatic changes and were predicted to target many mRNAs. Further studies will be needed to verify these predictions.

The complete mitogenome sequences of the palaeopteran insects Ephemera orientalis (Ephemeroptera: Ephemeridae) and Davidius lunatus (Odonata: Gomphidae).

Currently, the palaeopteran lineages (insect orders Ephemeroptera and Odonata) that have a problematic relationship with neopteran lineages are poorly represented by mitogenome sequences. In this study, we have determined the complete mitogenome of the oriental mayfly, Ephemera orientalis (Ephemeroptera: Ephemeridae), and the dragonfly Davidius lunatus (Odonata: Gomphidae). The 16 463 bp mitogenome of E. orientalis and the 15 912 bp mitogenome of D. lunatus have many of the features typically detected in insect mitogenomes. Although the initiation codon for the D. lunatus COI gene is the typical ATA, E. orientalis is unusual in that no typical start codon was detected in the start region of the COI gene. The A+T-rich regions of both mitogenomes have some unusual features. The E. orientalis A+T-rich region harbors two identical 55 bp sequences separated by 158 bp, and the D. lunatus A+T-rich region harbors a tandem repeat comprising two identical 261 bp copies and one partial copy of the repeat. Additionally, the A+T-rich regions of both mitogenomes harbor the stem-and-loop structures flanked by the conserved sequences "TA(A)TA" at the 5' end and "G(A)nT" at the 3' end, which have been suggested to be the signals involved in minor strand replication initiation. Furthermore, the D. lunatus A+T-rich region contains two tRNA-like structures with proper anticodon and cloverleaf structures.

Alteration of miRNA profiles by ionizing radiation in A549 human non-small cell lung cancer cells.

Ionizing radiation (IR) is widely used in cancer treatment and in biological studies. It disrupts cellular homeostasis through multiple mechanisms including changes of the expression profile of genes. Although microRNAs (miRNAs) have recently been recognized as important post-transcriptional regulators and are involved in various biological processes, whether miRNAs play any roles in the cellular response to IR, is not well examined. We investigated the profile of miRNA expression following IR in the human lung carcinoma cell line A549, and the expression profiles of IR-responsive miRNAs were confirmed by qRT-PCR. The target mRNAs of IR-responsive miRNAs were predicted with a target prediction tool. Microarray analysis identified 12 and 18 miRNAs in 20- and 40 Gy-exposed A549 cells, respectively, that exhibited more than 2-fold changes in their expression levels. Of these, four were changed in only 20-Gy-treated cells, ten only in 40-Gy-treated cells, and eight miRNAs were found to change after both treatments. qRT-PCR analysis of a subset of the miRNAs showed patterns of regulation as the microarray data, although the magnitude of the changes differed in the two data sets. Target prediction for IR-responsive miRNAs suggests that they target genes related to apoptosis, regulation of cell cycle, and DNA damage and repair. Taken together, these data suggest that miRNA expression is affected by radiation, and they may be involved in the regulation of radiation responses.

Suberoylanilide hydroxamic acid (SAHA) changes microRNA expression profiles in A549 human non-small cell lung cancer cells.

Suberoylanilide hydroxamic acid (SAHA) is a histone deacetylase inhibitor (HDACI) with antitumor effects that is being explored as a therapeutic drug. However, it has been reported that non-small cell lung cancer (NSCLC) is resistant to HDACIs. MicroRNAs (miRNAs) are a key class of small, non-coding RNA molecules that modulate post-transcriptional regulation of gene expression in multi-cellular organisms. miRNA expression patterns are involved in deregulation of gene expression in human lung cancer. Here we identified miRNA expression profile changes in response to SAHA treatment in the human lung carcinoma cell line A549. We also examined potential mRNA targets of SAHA-responsive miRNAs by using a target prediction program. Using microarray analysis, we found 64 miRNAs with >2-fold expression changes in SAHA-treated A549 cells. Among them, two unique miRNAs were altered in 2.5 microM SAHA-treated cells, 31 unique miRNAs were altered in 5.0 microM SAHA-treated cells and 31 miRNAs were altered with both doses. These miRNAs are predicted to have several target genes related to angiogenesis, apoptosis, chromatin modification, cell proliferation and differentiation. In conclusion, we have identified a unique set of miRNAs and their expression profiles that are influenced significantly by SAHA in the A549 NSCLC cell line model, which might provide useful information for understanding the anticancer mechanism of SAHA.

MicroRNAs are significantly influenced by p53 and radiation in HCT116 human colon carcinoma cells.

Ionizing radiation is genotoxic to the cell, and p53 is commonly considered to be a key regulator that controls gene expression responding to the genotoxity of radiation. The expression profiles of microRNAs (miRNAs), which are small non-coding RNAs regulating the translation of target mRNAs, were analyzed to determine whether any correlation exists between miRNA expression, radiation response, and/or p53. The miRNA profiles were analyzed by microarray containing 470 human miRNA probes in HCT116 human colon carcinoma cells and their p53-null derivative. Thirty-eight miRNAs among the 138 flagged human miRNAs were selected by fold-change analysis. The expression levels of these 38 miRNAs were changed more than two-fold, and a total of 12 miRNAs were significantly affected by p53, radiation, and the combination of both. All 12 miRNAs had expression patterns correlated to p53, while two miRNAs were affected by radiation or the combined action of radiation and p53. In bioinformatics studies, these miRNAs had p53-binding sites with scores higher than 85% in their upstream regions, and some of their target genes were found to be involved in genotoxic responses. In conclusion, we have identified miRNAs influenced significantly by p53 and/or radiation in the HCT116 human colon carcinoma cell line model, and these miRNAs may have important roles in the regulation of genes involved the cellular responses to radiation.

Identification of ionizing radiation-responsive microRNAs in the IM9 human B lymphoblastic cell line.

Ionizing radiation (IR) disrupts cellular homeostasis through multiple mechanisms including changes of the expression profile of genes. Although microRNAs (miRNAs), small single-stranded RNAs, have recently been recognized as important post-transcriptional regulators of gene expression, it is not well investigated if miRNAs function in the cellular response to radiation. Therefore, we determined if IR induces changes in the expression profiles of miRNAs and used this approach to identify IR-responsive miRNAs. To monitor the profiles of miRNAs, microarray analysis was conducted with irradiated IM9 human lymphoblastic cells. The expression levels of specific miRNAs were confirmed by quantitative real-time PCR (qRT-PCR) and statistically analyzed. Finally, the target mRNAs of some IR-responsive miRNAs were predicted with two different prediction programs. IR-exposed human lymphoblastic cells underwent cell cycle arrest and apoptosis. Apoptosis was more significantly increased at a higher radiation dose. There were 73 and 33 human miRNAs in 1 and 10 Gy-irradiated cells, respectively that showed expression level changes of >2-fold. By qRT-PCR analysis, it was revealed that the patterns of miRNA expression were similar to those observed in the microarray data, although the quantitative expression levels were discordant. Prediction of genes targeted by IR-responsive miRNA yielded several genes, many of which are involved in the regulation of apoptosis, the cell cycle, and DNA repair. The expression profiles of miRNAs in the IM9 human B lymphoblastic cells are strongly affected by IR and these changes may be involved in the regulation of cellular response to IR.

Complete nucleotide sequence and organization of the mitogenome of the silk moth Caligula boisduvalii (Lepidoptera: Saturniidae) and comparison with other lepidopteran insects.

The 15,360-bp long complete mitogenome of Caligula boisduvalii possesses a gene arrangement and content identical to other completely sequenced lepidopteran mitogenomes, but different from the common arrangement found in most insect order, as the result of the movement of tRNA(Met) to a position 5'-upstream of tRNA Ile. The 330-bp A+T-rich region is apparently capable of forming a stem-and-loop structure, which harbors the conserved flanking sequences at both ends. Dissimilar to what has been seen in other sequenced lepidopteran insects, the initiation codon for C. boisduvalii COI appears to be TTG, which is a rare, but apparently possible initiation codon. The ATP8, ATP6, ND4L, and ND6 genes, which neighbor another PCG at their 3' end, all harbored potential sequences for the formation of a hairpin structure. This is suggestive of the importance of such structures for the precise cleavage of the mRNA of mature PCGs. Phylogenetic analyses of available sequenced species of Bombycoidea, Pyraloidea, and Tortricidea supported the morphology-based current hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As previously suggested, Bombycidae (Bombyx mori and B. mandarina) and Saturniidae (Antheraea pernyi and C. boisduvalii) formed a reciprocal monophyletic group.

The complete nucleotide sequence and gene organization of the mitochondrial genome of the bumblebee, Bombus ignitus (Hymenoptera: Apidae).

The complete 16,434-bp nucleotide sequence of the mitogenome of the bumble bee, Bombus ignitus (Hymenoptera: Apidae), was determined. The genome contains the base composition and codon usage typical of metazoan mitogenomes. An unusual feature of the B. ignitus mitogenome is the presence of five tRNA-like structures: two each of the tRNALeu(UUR)-like and tRNASer(AGN)-like sequences and one tRNAPhe-like sequence. These tRNA-like sequences have proper folding structures and anticodon sequences, but their functionality in their respective amino acid transfers remained uncertain. Among these sequences, the tRNALeu(UUR)-like sequence and the tRNASer(AGN)-like sequence are seemingly located within the A+T-rich region. This tRNASer(AGN)-like sequence is highly unusual in that its sequence homology is very high compared to the tRNAMet of other insects, including Apis mellifera, but it contains the anticodon ACT, which designates it as tRNASer(AGN). All PCG and rRNAs are conserved in positions observed most frequently in insect mitogenome structures, but the positions of the tRNAs are highly variable, presenting a new arrangement for an insect mitogenome. As a whole, the B. ignitus mitogenome contains the highest A+T content (86.9%) found in any of the complete insects mt sequences determined to date. All protein-coding sequences started with a typical ATN codon. Nine of the 13 PCGs have a complete termination codon (all TAA), but the remaining four genes terminate with the incomplete TA or T. All tRNAs have the typical clover-leaf structures of mt tRNAs, except for tRNASer(AGN), in which the DHU arm forms a simple loop. All anticodons of B. ignitus tRNAs are identical to those of A. mellifera. In the A+T-rich region, a highly conserved sequence block that was previously described in Orthoptera and Diptera was also present. The stem-and-loop structures that may play a role in the initiation of mtDNA replication were also found in this region. Phylogenetic analysis among three corbiculate tribes, represented by Melipona bicolor (Meliponini), A. mellifera (Apini), and B. ignitus (Bombini), showed the closest relationship between M. bicolor and B. ignitus.