Characterization of miRNAs in Embryonic, Larval, and Adult Lumpfish Provides a Reference miRNAome for Cyclopterus lumpus

MicroRNAs (miRNAs) are endogenous small RNA molecules involved in the post-transcriptional regulation of protein expression by binding to the mRNA of target genes. They are key regulators in teleost development, maintenance of tissue-specific functions, and immune responses. Lumpfish (Cyclopterus lumpus) is becoming an emergent aquaculture species as it has been utilized as a cleaner fish to biocontrol sea lice (e.g., Lepeophtheirus salmonis) infestation in the Atlantic Salmon (Salmo salar) aquaculture. The lumpfish miRNAs repertoire is unknown. This study identified and characterized miRNA encoding genes in lumpfish from three developmental stages (adult, embryos, and larvae). A total of 16 samples from six different adult lumpfish organs (spleen, liver, head kidney, brain, muscle, and gill), embryos, and larvae were individually small RNA sequenced. Altogether, 391 conserved miRNA precursor sequences (discovered in the majority of teleost fish species reported in miRbase), eight novel miRNA precursor sequences (so far only discovered in lumpfish), and 443 unique mature miRNAs were identified. Transcriptomics analysis suggested organ-specific and age-specific expression of miRNAs (e.g., miR-122-1-5p specific of the liver). Most of the miRNAs found in lumpfish are conserved in teleost and higher vertebrates, suggesting an essential and common role across teleost and higher vertebrates. This study is the first miRNA characterization of lumpfish that provides the reference miRNAome for future functional studies.

In silico study predicts a key role of RNA-binding domains 3 and 4 in nucleolin-miRNA interactions.

RNA binding proteins (RBPs) regulate many important cellular processes through their interactions with RNA molecules. RBPs are critical for post-transcriptional mechanisms keeping gene regulation in a fine equilibrium. Conversely, dysregulation of RBPs and RNA metabolism pathways is an established hallmark of tumorigenesis. Human nucleolin (NCL) is a multifunctional RBP that interacts with different types of RNA molecules, in part through its four RNA binding domains (RBDs). Particularly, NCL interacts directly with microRNAs (miRNAs) and is involved in their aberrant processing linked with many cancers, including breast cancer. Nonetheless, molecular details of the NCL-miRNA interaction remain obscure. In this study, we used an in silico approach to characterize how NCL targets miRNAs and whether this specificity is imposed by a definite RBD-interface. Here, we present structural models of NCL-RBDs and miRNAs, as well as predict scenarios of NCL- miRNA interactions generated using docking algorithms. Our study suggests a predominant role of NCL RBDs 3 and 4 (RBD3-4) in miRNA binding. We provide detailed analyses of specific motifs/residues at the NCL-substrate interface in both these RBDs and miRNAs. Finally, we propose that the evolutionary emergence of more than two RBDs in NCL in higher organisms coincides with its additional role/s in miRNA processing. Our study shows that RBD3-4 display sequence/structural determinants to specifically recognize miRNA precursor molecules. Moreover, the insights from this study can ultimately support the design of novel antineoplastic drugs aimed at regulating NCL-dependent biological pathways with a causal role in tumorigenesis.

Identification of lncRNAs Differentially Expressed during Natural and Induced Estrus in Sheep

Background: The manipulation of the estrous cycle or induction of estrus is a commonly used technique in sheep industry. The goal of this study was to identify and characterize differences of non-coding RNAs (lincRNAs) expression between induced estrus and natural estrus using the BGISEQ-500 plat form in 7 Mongolian sheep, which will provide insights into the regulation mechanisms of lncRNAs in different reproduction mode of sheep. Methods: During the late spring, ovarian, pituitary, hypothalamic, pineal and uterine tissue samples were collected from four artificially induced estrus and three naturally estrus Mongolian sheep. Total RNA was extracted from the five tissues using TRIzol reagent (Invitrogen) and treated with DNase I following the manufacturer’s instructions. A total of 35 sheep samples were sequenced using the BGISEQ-500 plat form. Bioinformatics methods were used to analysis expression difference analysis between groups, SNP and InDel, alternative splicing, lncRNA’s miRNA precursor prediction, lncRNA target gene and family prediction. Result: 211 novel lncRNAs were systematically identified using RNA-Seq technology. Meanwhile, we found that there are diversifications of lncRNAs in induced estrus vs. nature estrus of ewes. Therefore, we predict that, under the action of exogenous hormones, many physiological processes of ewes may be affected to varying degrees through the change of LncRNA to a variety of pathways.

In silico study predicts a key role of RNA-binding domains 3 and 4 in nucleolin-miRNA interactions.

RNA binding proteins (RBPs) regulate many important cellular processes through their interactions with RNA molecules. RBPs are critical for post-transcriptional mechanisms keeping gene regulation in a fine equilibrium. Conversely, dysregulation of RBPs and RNA metabolism pathways is an established hallmark of tumorigenesis. Human nucleolin (NCL) is a multifunctional RBP that interacts with different types of RNA molecules, in part through its four RNA binding domains (RBDs). Particularly, NCL interacts directly with microRNAs (miRNAs) and is involved in their aberrant processing linked with many cancers, including breast cancer. Nonetheless, molecular details of the NCL-miRNA interaction remain obscure. In this study, we used an in silico approach to characterize how NCL targets miRNAs and whether this specificity is imposed by a definite RBD-interface. Here, we present structural models of NCL RBDs and miRNAs, as well as predict scenarios of NCL- miRNA interactions generated using docking algorithms. Our study suggests a predominant role of NCL RBDs 3 and 4 (RBD3-4) in miRNA binding. We provide detailed analyses of specific motifs/residues at the NCL-substrate interface in both these RBDs and miRNAs. Finally, we propose that the evolutionary emergence of more than two RBDs in NCL in higher organisms coincides with its additional role/s in miRNA processing. Our study shows that RBD3-4 display sequence/structural determinants to specifically recognize miRNA precursor molecules. Moreover, the insights from this study can ultimately support the design of novel antineoplastic drugs aimed at regulating NCL-dependent biological pathways with a causal role in tumorigenesis.

In silico Analysis of Polymorphisms in microRNAs Deregulated in Alzheimer Disease

BackgroundAlzheimer’s disease (AD) is a degenerative condition characterized by progressive cognitive impairment and dementia. Findings have revolutionized current knowledge of miRNA in the neurological conditions. Two regulatory mechanisms determine the level of mature miRNA expression; one is miRNA precursor processing, and the other is gene expression regulation by transcription factors. This study is allocated to the in-silico investigation of miRNA’s SNPs and their effect on other cell mechanisms.MethodsWe used databases which annotate the functional effect of SNPs on mRNA-miRNA and miRNA-RBP interaction. Also, we investigated SNPs which are located on the promoter or UTR region.ResultsmiRNA SNP3.0 database indicated several SNPs in miR-339 and miR-34a in the upstream and downstream of pre-miRNA and mature miRNAs. While, for some miRNAs miR-124, and miR-125, no polymorphism was observed, and also miR-101 with ΔG -3.1 and mir-328 with ΔG 5.8 had the highest and lowest potencies to produce mature microRNA. SNP2TFBS web-server presented several SNPs which altered the Transcription Factor Binding Sites (TFBS) or generated novel TFBS in the promoter regions of related miRNA. At last, RBP-Var database provided a list of SNPs which alter miRNA-RBP interaction pattern and can also influence other miRNAs’ expression.DiscussionThe results indicated that SNPs microRNA affects both miRNA function and miRNA expression. Our study expands molecular insight into how SNPs in different parts of miRNA, including the regulatory (promoter), the precursor (pre-miRNA), functional regions (seed region of mature miRNA), and RBP-binding motifs, which theoretically may be correlated to the Alzheimer’s disease.

De novo assembly and characterization of the first draft genome of quince (Cydonia oblonga Mill.)

Quince (Cydonia oblonga Mill.) is the sole member of the genus Cydonia in the Rosacea family and closely related to the major pome fruits, apple (Malus domestica Borkh.) and pear (Pyrus communis L.). In the present work, whole genome shotgun paired-end sequencing was employed in order to assemble the first draft genome of quince. A genome assembly that spans 488.4 Mb of sequence corresponding to 71.2% of the estimated genome size (686 Mb) was produced in the study. Gene predictions via ab initio and homology-based sequence annotation strategies resulted in the identification of 25,428 and 30,684 unique putative protein coding genes, respectively. 97.4 and 95.6% of putative homologs of Arabidopsis and rice transcription factors were identified in the ab initio predicted genic sequences. Different machine learning algorithms were tested for classifying pre-miRNA (precursor microRNA) coding sequences, identifying Support Vector Machine (SVM) as the best performing classifier. SVM classification predicted 600 putative pre-miRNA coding loci. Repetitive DNA content of the assembly was also characterized. The first draft assembly of the quince genome produced in this work would constitute a foundation for functional genomic research in quince toward dissecting the genetic basis of important traits and performing genomics-assisted breeding.

Immunological Off-Target Effects of microRNA Control Sequences.

Immunological off-target effects of RNA and RNAi therapy are a considerable challenge in research and the future of RNA-therapy. Here we investigated some of the hurdles we previously encountered when transfecting mircroRNA (miRNA) control sequences into chondrocytes in an inflammatory model simulating osteoarthritis (OA). We investigated different negative control sequences of different technologies; Pre-miR miRNA Precursor and mirVana from Thermo Fisher Scientific. We used RT-qPCR, western blot analysis and mass spectrometry to asses for the effects of the transfected control sequences.The data did not show a global immunological off-target effect, however a specific off-target effect on IL6 and IL8 was observed. IL6 and IL8 were both upregulated by the negative control from the Pre-miR miRNA Precursor technology (Pre-neg #1), and downregulated by the negative control from the mirVana technology (mirVana-neg). Moreover, the results suggested that the effect on IL6 and IL8 was dependent on both sequence and type of chemical modifications in addition to donor variation. We conclude that negative controls should be selected wisely, and suggest that scientists need to test several controls to ensure correct interpretation of data before drawing any conclusions.

Dissecting seed pigmentation-associated genomic loci and genes by employing dual approaches of reference-based and k-mer-based GWAS with 438 Glycine accessions

The soybean is agro-economically the most important among all cultivated legume crops, and its seed color is considered one of the most attractive factors in the selection-by-breeders. Thus, genome-wide identification of genes and loci associated with seed colors is critical for the precision breeding of crop soybeans. To dissect seed pigmentation-associated genomic loci and genes, we employed dual approaches by combining reference-based genome-wide association study (rbGWAS) and k-mer-based reference-free GWAS (rfGWAS) with 438 Glycine accessions. The dual analytical strategy allowed us to identify four major genomic loci (designated as SP1-SP4 in this study) associated with the seed colors of soybeans. The k-mer analysis enabled us to find an important recombination event that occurred between subtilisin and I-cluster B in the soybean genome, which could describe a special structural feature of ii allele within the I locus (SP3). Importantly, mapping analyses of both mRNAs and small RNAs allowed us to reveal that the subtilisin-CHS1/CHS3 chimeric transcripts generate and act as an initiator towards ‘mirtron (i.e., intron-harboring miRNA precursor)’-triggered silencing of chalcone synthase (CHS) genes. Consequently, the results led us to propose a working model of ‘mirtron-triggered gene silencing (MTGS)’ to elucidate a long-standing puzzle in the genome-wide CHS gene silencing mechanism. In summary, our study reports four major genomic loci, lists of key genes and genome-wide variations that are associated with seed pigmentation in soybeans. In addition, we propose that the MTGS mechanism plays a crucial role in the genome-wide silencing of CHS genes, thereby suggesting a clue to currently predominant soybean cultivars with the yellow seed coat. Finally, this study will provide a broad insight into the interactions and correlations among seed color-associated genes and loci within the context of anthocyanin biosynthetic pathways.

H-Ras Pre-mRNA Contains A Regulatory Non-coding RNA

Non-coding RNAs (ncRNAs) have emerged as one of the most abundant regulatory molecules. However, their roles and functions are significantly different from those of proteins. Moreover, around 95% of the human genome contains non-coding DNA. ncRNAs contribute by far the majority of human transcriptional units, and the functions of the most are yet unknown. Here, we highlight that an important RNA sequence region, encompassing an exon-intron hairpin loop (also called IDX-rasISS1), of the H-Ras pre-mRNA may encode an ncRNA that regulates p68 RNA helicase. This observation is remarkable owing to the fact that this helicase is responsible for upregulating the hairpin loop. This indicates that an inhibitory feedback mechanism acting on the p68 RNA helicase is mediated by higher structural levels of the hairpin-loop. Initially, two observations prompted the present study: i) previous results revealed down-regulation of p68 RNA helicase resulting from overexpression of the IDX hairpin loop in HeLa cells, and ii) the secondary structure of the IDX hairpin loop resembles pri-miRNAs, implying that an miRNA could be processed from the hairpin loop-containing pri-miRNA and regulate 68 RNA helicase. To validate our hypothesis, we directly compared p68 RNA sequences and the hairpin loop in silico. Furthermore, RNAi assays containing the hairpin loop as an miRNA precursor were conducted, using the pTer vector, to explore the effects on 68 RNA helicase expression levels. These RNAi analyses were quantified by Western blots (using anti-p68 RNA helicase and anti-EIF2α) and Fluc/Rluc 3’UTRs/CDS assays. The effect of hairpin loop overexpression on cell growth and cancer processes was also investigated by analyzing cell-cycle phases and miR-206 expression. Finally, alternative splicing microarrays containing apoptosis targets were incubated to verify whether pre-mRNAs other than H-Ras could also present a similar hairpin loop structure regulated by p68 RNA helicase. We observed that overexpression of the hairpin loop does not activate the phosphorylation of EIF2α and, therefore, does not activate PKR interferon-induced apoptosis. Moreover, a similar effect on p68 RNA helicase-mediated interference is observed during the upregulation of the hairpin loop. Finally, we also identified a similar hairpin loop-like structure in an alternative splicing region of MAPK12/ERK6. Thus it can be inferred from our findings that the alternative splicing exon IDX from H-Ras, coupled with the immediately downstream intron sequences, may contain an ncRNA. We also unveil one potential function of this ncRNA whose expression is regulated by alternative splicing decisions.