Corrigendum to: Elucidating the Functional Role of Predicted miRNAs in Post-Transcriptional Gene Regulation Along with Symbiosis in Medicago truncatula

Background: microRNAs are small non-coding RNAs which inhibit translational and post-transcriptional processes whereas long non-coding RNAs are found to regulate both transcriptional and post-transcriptional gene expression. Medicago truncatula is a well-known model plant for studying legume biology and is also used as a forage crop. In spite of its importance in nitrogen fixation and soil fertility improvement, little information is available about Medicago non-coding RNAs that play important role in symbiosis. Objective: In this study we have tried to understand the role of Medicago ncRNAs in symbiosis and regulation of transcription factors. Methods: We have identified novel miRNAs by computational methods considering various parameters like length, MFEI, AU content, SSR signatures and tried to establish an interaction model with their targets obtained through psRNATarget server. Results: 149 novel miRNAs are predicted along with their 770 target proteins. We have also shown that 51 of these novel miRNAs are targeting 282 lncRNAs. Conclusion: In this study role of Medicago miRNAs in the regulation of various transcription factors are elucidated. Knowledge gained from this study will have a positive impact on the nitrogen fixing ability of this important model plant, which in turn will improve the soil fertility.

The genome continues to fascinate the enthusiasts, and the captivation seems unabating because of the continuous stream of new discoveries. What was once considered a junk DNA has now emerged to contain a large number of important regulatory elements.1 As an example of such discoveries is the recent finding that the genome contains ≈6200 enhancer elements that are operational in the human fetal and adult hearts.2 Genes occupy only ≈1.5% and coding exons only ≈1% of the genome, which make up only ≈60 million nucleotides of the 6.4 billion nucleotides (3.2 billion base pairs) in the genome.3 Yet, ≈5% of the human genome has undergone purifying selection and hence are likely functional.4 It is intriguing that about two third of the evolutionary constrained genomic elements are located in introns and the intergenic regions, suggestive of their regulatory roles in the genome.4 These conserved regions are enriched in loci that have been found to be associated with clinical phenotypes in the genome-wide association studies.4 The initial findings of the ENCODE (Encyclopedia of DNA Elements) project, although preliminary, illustrate the presence of numerous regulatory elements in the genome, including the enhancers.1 The discoveries largely made possible by the recent advances in the high-throughput RNA sequencing point to enormous RNA splicing diversity and the plethora of alternative splicing variants. Approximately 95% of the multiexon genes undergo alternative splicing, resulting in ≈100 000 abundant splice variants in various tissues.5 Moreover, it seems that almost all genomic regions in 1 form or shape are transcribed, which seems perplexing as only ≈1% of the genome codes for proteins, as has been understood to date. Only recently we have started to appreciate the diverse biological functions of these nonprotein coding transcripts, which are referred to as noncoding RNAs (ncRNAs). …

In spite of prolonged and intensive treatment with combined antiretroviral therapy (cART), which efficiently suppresses plasma viremia, the integrated provirus of HIV-1 persists in resting memory CD4+ T cells as latent infection. Treatment with cART does not substantially reduce the burden of latent infection. Once cART is ceased, HIV-1 replication recrudesces from these reservoirs in the overwhelming majority of patients. There is increasing evidence supporting a role for noncoding RNAs (ncRNA), including microRNAs (miRNAs), antisense (as)RNAs, and short interfering (si)RNA in the regulation of HIV-1 transcription. This appears to be mediated by interaction with the HIV-1 promoter region. Viral miRNAs have the potential to act as positive or negative regulators of HIV transcription. Moreover, inhibition of virally encoded long-asRNA can induce positive transcriptional regulation, while antisense strands of siRNA targeting the NF-κB region suppress viral transcription. An in-depth understanding of the interaction between ncRNAs and the HIV-1 U3 promoter region may lead to new approaches for the control of HIV reservoirs. This review focuses on promoter associated ncRNAs, with particular emphasis on their role in determining whether HIV-1 establishes active or latent infection.

Expression quantitative trait loci (eQTL) studies typically consider exon expression of genes and discard intronic RNA sequencing reads despite their information on RNA metabolism. Here, we quantify genetic effects on exon and intron levels of genes and their ratio in lymphoblastoid cell lines, revealing thousands of cis-QTLs of each type. While genetic effects are often shared between cis-QTL types, 7814 (47%) are not detected as top cis-QTLs at exon levels. We show that exon levels preferentially capture genetic effects on transcriptional regulation, while exon-intron-ratios better detect those on co- and post-transcriptional processes. Considering all cis-QTL types substantially increases (by 71%) the number of colocalizing variants identified by genome-wide association studies (GWAS). It further allows dissecting the potential gene regulatory processes underlying GWAS associations, suggesting comparable contributions by transcriptional (50%) and co- and post-transcriptional regulation (46%) to complex traits. Overall, integrating intronic RNA sequencing reads in eQTL studies expands our understanding of genetic effects on gene regulatory processes.

Inflammatory breast cancer (IBC) is the most aggressive and lethal breast cancer subtype but lacks unequivocal genomic differences or robust biomarkers that differentiate it from non-IBC. Here, Thermostable Group II intron Reverse Transcriptase RNA-sequencing (TGIRT-seq) revealed myriad differences in tumor samples, Peripheral Blood Mononuclear Cells (PBMCs), and plasma that distinguished IBC from non-IBC patients and healthy donors across all tested receptor-based subtypes. These included numerous differentially expressed protein-coding gene and non-coding RNAs in all three sample types, a granulocytic immune response in IBC PBMCs, and over-expression of antisense RNAs, suggesting wide-spread enhanced transcription in both IBC tumors and PBMCs. By using TGIRT-seq to quantitate Intron-exon Depth Ratios (IDRs) and mapping reads to both genome and transcriptome reference sequences, we developed methods for parallel analysis of transcriptional and post-transcriptional gene regulation. This analysis identified numerous differentially and non-differentially expressed protein-coding genes in IBC tumors and PBMCs with high IDRs, the latter reflecting rate-limiting RNA splicing that negatively impacts mRNA production. Mirroring gene expression differences in tumors and PBMCs, over-represented protein-coding gene RNAs in IBC patient plasma were largely intronic RNAs, while those in non-IBC patients and healthy donor plasma were largely mRNA fragments. Potential IBC biomarkers in plasma included T-cell receptor pre-mRNAs and intronic, LINE-1, and antisense RNAs. Our findings provide new insights into IBC and set the stage for monitoring disease progression and response to treatment by liquid biopsy. The methods developed for parallel transcriptional and post-transcriptional gene regulation analysis have potentially broad RNA-seq and clinical applications.

Plant sensing drought stress conditions activate complex molecular networks leading to a rapid reprogramming of plant physiology and metabolism, in order to survive in suboptimal conditions.Here, we describe a standardized in vivo soil drought assay to investigate the effects of drought stress on leaf growth. Since it is now clear that stress responses can be specific to developmental stages and cell types, we describe a procedure to dissect the leaf in three distinct areas in order to study transcriptional and posttranscriptional gene regulation on both organ and cellular levels. Noncoding RNAs, both small RNAs and long noncoding RNAs, are emerging to be deeply involved in abiotic stress responses, acting as molecular switches, interconnecting different response pathways. Here, we illustrate the methodology that has been used to identify miRNAs involved in drought response and to analyze the modulation of expression of their putative targets, in order to gain a complete picture of transcriptional and posttranscriptional regulation driven by noncoding RNAs.

Background: Long non-coding RNAs (lncRNAs) have emerged as key components of transcriptional and post-transcriptional gene regulation. Dysregulation of lncRNA expression has been widely observed in cancer and several lncRNAs are known to influence tumor initiation and progression. Despite this, the lncRNA landscape and regulatory networks across pediatric cancers remain relatively uncharted. Methods: To characterize the lncRNA landscape of pediatric cancers, we first curated RNA sequencing data for 1,044 pediatric leukemia and solid tumors from the Therapeutically Applicable Research To Generate Effective Treatments (TARGET) project to identify known and novel expressed lncRNAs. This data set included: 280 acute myeloid leukemia (AML), 190 acute B-cell leukemia (B-ALL), 244 acute T-cell leukemia (T-ALL), 121 Wilm's tumor (WT), 48 rhabdoid tumors (RT), and 161 neuroblastoma (NBL). Histotype-specific expression was assessed using the tau score. Whole genome sequencing (WGS) from 826 matched normal-tumor pairs was integrated to identify somatic copy number alterations (SCNAs) disrupting lncRNA expression. To further implicate cancer-relevant drivers of lncRNA expression, we used a unique combination of epigenetic data in pediatric cell lines, including ChIP-sequencing for cancer-specific transcription factors and genome-scale chromatin capture data. A global analysis of lncRNA function was performed using the lncMod method, in which expression data is modelled to identify lncRNA modulators that perturb transcription factor regulation of target genes. Functional prioritization of lncRNAs was obtained through integration of analyses per cancer. Biochemical assays in human-derived cell line models were utilized to validate the function of the top prioritized lncRNA in NBL. Results: We report a total of 2,657 robustly expressed lncRNAs across six pediatric cancers, including 1,142 lncRNAs exhibiting histotype-specific expression. SCNAs contributed to lncRNA dysregulation at a proportion comparable to protein coding genes. There were 207 (28%) lncRNAs in regions with SCNA that had significant expression dysregulation. LncMod analysis across the cancers revealed context-specific transcriptional gene networks per dysregulated lncRNA and enrichment for proliferation, metabolic, and DNA damage hallmarks. We further identified 547 cancer-associated lncRNAs in NBL based on upstream regulation via oncogenic transcription factors. The top-prioritized lncRNA, TBX2-AS1, was predicted to impact proliferation in NBL. Silencing of TBX2-AS1 using siRNAs achieved >90% knockdown in NBL cells and resulted in 46.6% decreased cell growth (p = 8.1 x 10-4). Conclusion: This study defines the lncRNA landscape across six pediatric cancers and provides a detailed catalog of how lncRNAs impact regulatory gene networks. These data serve as a robust resource for future hypothesis-driven mechanistic studies. Citation Format: Apexa Modi, Gonzalo Lopez, Karina L. Conkrite, Tsz Ching Leung, Sathvik Ramanan, Daphne Cheung, Chun Su, Matthew E. Johnson, Elisabetta Manduchi, Samantha Gadd, Jinghui Zhang, Malcolm A. Smith, Jaime M. Guidry Auvil, Daniela S. Gerhard, Soheil Meshinchi, Elizabeth J. Perlman, Stephen P. Hunger, John M. Maris, Andrew D. Wells, Struan F. Grant, Sharon J. Diskin. Integrative genomics reveals lncRNAs associated with pediatric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3028.

Lignin is a heterogeneous polymer of aromatic subunits derived from phenylalanine. It is polymerized in intimate proximity to the polysaccharide components in plant cell walls and provides additional rigidity and compressive strength for plants. Understanding the regulatory mechanisms of lignin biosynthesis is important for genetic modification of the plant cell wall for agricultural and industrial applications. Over the past 10 years the transcriptional regulatory model of lignin biosynthesis has been established in plants. However, the role of post-transcriptional regulation is still largely unknown. Increasing evidence suggests that lignin biosynthesis pathway genes are also regulated by alternative splicing, microRNA, and long non-coding RNA. In this review, we briefly summarize recent progress on the transcriptional regulation, then we focus on reviewing progress on the post-transcriptional regulation of lignin biosynthesis pathway genes in the woody model plant Populus.

Gene regulation is a complex biological phenomenon. A reliable analysis of this process requires the integration of several data sources in a rigorous pipeline. Here, we propose an approach for simultaneous modeling of transcriptional and post-transcriptional gene regulation over a Bayesian module network. The framework uses paired samples of mRNA and microRNA expressions and their sequence data to produce low-level regulatory circuits in addition to the co-regulated entities of mRNAs, microRNAs and transcription factors. The experiments performed on a real cancer dataset reveal that several biologically meaningful clusters and motifs can be inferred. The results lead to the generation of some testable biological hypotheses.

In spite of a large body of information about the upstream regulators of metastasis, a process that often plays a limiting factor in therapeutic outcome of cancer patients, the impact of regulatory microRNA patterns remains obscure. This review describes computational analysis of coordinated regulation of genes by di-directional regulation of microRNA and transcription factors that specifically regulate the process of metastasis. We discovered several unexpected modes of regulatory patterns between microRNAs and transcription factors. For example, we found a double positive feedback loop regulated by the hub transcription factor ZEB1 and miR-200 during epithelial-mesenchymal transition. This review further explains flow of information and how such components coordinate various adaptable controls of microRNAs and thus, contribute to regulation of transcription factors in context of cancer metastasis. Information described here provides a regulatory framework for future experimental analyses and discoveries of new insights into post-transcriptional gene regulation at the microRNA level in cancer metastasis.

Noncoding RNAs have emerged as important regulators of cellular and systemic lipid metabolism. In particular, the enigmatic class of long noncoding RNAs have been shown to play multifaceted roles in controlling transcriptional and posttranscriptional gene regulation. In this review, we discuss recent advances, current challenges and future opportunities in understanding the roles of lncRNAs in the regulation of lipid metabolism during health and disease. Despite comprising the majority of the transcriptionally active regions of the human genome, lncRNA functions remain poorly understood, with fewer than 1% of human lncRNAs functionally characterized. Broadly defined as nonprotein coding transcripts greater than 200 nucleotides in length, lncRNAs execute their functions by forming RNA-DNA, RNA-protein, and RNA-RNA interactions that regulate gene expression through diverse mechanisms, including epigenetic remodeling of chromatin, transcriptional activation or repression, posttranscriptional regulation of mRNA, and modulation of protein activity. It is now recognized that in lipid metabolism, just as in other areas of biology, lncRNAs operate to regulate the expression of individual genes and gene networks at multiple different levels. The complexity revealed by recent studies showing how lncRNAs can alter systemic and cell-type-specific cholesterol and triglyceride metabolism make it clear that we have entered a new frontier for discovery that is both daunting and exciting.

BackgroundLong intergenic noncoding RNAs (lincRNAs) are endogenous non-coding RNAs (ncRNAs) that are transcribed from ‘intergenic’ regions of the genome and may play critical roles in regulating gene expression through multiple RNA-mediated mechanisms. MicroRNAs (miRNAs) are single-stranded small ncRNAs of approximately 21–24 nucleotide (nt) that are involved in transcriptional and post-transcriptional gene regulation. While miRNAs functioning as mRNA repressors have been studied in detail, the influence of miRNAs on lincRNAs has seldom been investigated in plants.MethodsLincRNAs as miRNA targets or decoys were predicted via GSTAr.pl script with a set of rules, and lincRNAs as miRNA targets were validated by degradome data. Conservation analysis of lincRNAs as miRNA targets or decoys were conducted using BLASTN and MAFFT. The function of lincRNAs as miRNA targets were predicted via a lincRNA-mRNA co-expression network, and the function of lincRNAs as miRNA decoys were predicted according to the competing endogenous RNA (ceRNA) hypothesis.ResultsIn this work, we developed a computational method and systematically predicted 466 lincRNAs as 165 miRNA targets and 86 lincRNAs as 58 miRNA decoys in maize (Zea mays L.). Furthermore, 34 lincRNAs predicted as 33 miRNA targets were validated based on degradome data. We found that lincRNAs acting as miRNA targets or decoys are a common phenomenon, which indicates that the regulated networks of miRNAs also involve lincRNAs. To elucidate the function of lincRNAs, we reconstructed a miRNA-regulated network involving 78 miRNAs, 117 lincRNAs and 8834 mRNAs. Based on the lincRNA-mRNA co-expression network and the competing endogenous RNA hypothesis, we predicted that 34 lincRNAs that function as miRNA targets and 86 lincRNAs that function as miRNA decoys participate in cellular and metabolic processes, and play role in catalytic activity and molecular binding functions.ConclusionsThis work provides a comprehensive view of miRNA-regulated networks and indicates that lincRNAs can participate in a layer of regulatory interactions as miRNA targets or decoys in plants, which will enable in-depth functional analysis of lincRNAs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2024-0) contains supplementary material, which is available to authorized users.

Background:Rheumatoid arthritis (RA) is a serious autoimmune inflammatory disease[1]. Numerous studies have demonstrated that lncRNAs exert regulatory control over target gene expression at transcriptional, posttranscriptional, and posttranslational level[2], and may...

Advances in genomics technology over recent years have led to the surprising discovery that the genome is far more pervasively transcribed than was previously appreciated. Much of the newly-discovered transcriptome appears to represent long non-coding RNA (lncRNA), a heterogeneous group of largely uncharacterised transcripts. Understanding the biological function of these molecules represents a major challenge and in this review we discuss some of the progress made to date. One major theme of lncRNA biology seems to be the existence of a network of interactions with microRNA (miRNA) pathways. lncRNA has been shown to act as both a source and an inhibitory regulator of miRNA. At the transcriptional level, a model is emerging whereby lncRNA bridges DNA and protein by binding to chromatin and serving as a scaffold for modifying protein complexes. Such a mechanism can bridge promoters to enhancers or enhancer-like non-coding genes by regulating chromatin looping, as well as conferring specificity on histone modifying complexes by directing them to specific loci.

Chapter 8 - Role of long noncoding RNAs during stress in cereal crops