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The Reference Transcriptomic Dataset (RTD) is an accurate and comprehensive collection of transcripts originating from a given organism. It holds the key to precise transcript quantification and downstream analysis of differential expressions and regulations. Currently, transcriptome annotations for most crop plants are far from complete. For example, Oryza sativa indica (O. sativa indica) is reported to have 40,759 transcripts in the Ensembl database without alternative transcript isoforms and alternative splicing (AS) events. To generate a high-quality RTD, we conducted RNA sequencing of rice leaf samples collected at various time points during Rhizoctonia solani infection. The obtained reads were analyzed by adopting the recently developed computational analysis pipeline to assemble the RTD with increased transcript and AS diversity for O. sativa indica (IndicaRTD). After stringent quality filtering, the newly constructed transcriptome annotation was comprised of 122,968 non-redundant transcripts from 53,695 genes. This study identified many novel transcripts compared to Ensembl deposited data that are important for regulating molecular and physiological processes in the plant system. Currently, the assembled IndicaRTD must allow fast quantification of transcript and gene expression with high precision.

The Reference Transcriptomic Dataset (RTD) is an accurate and comprehensive collection of transcripts originating from a given organism. It holds the key to precise transcript quantification and downstream analysis of differential expressions and regulations. Currently, transcriptome annotations for most crop plants are far from complete. For example

Sheath blight (ShB) disease, caused by Rhizoctonia solani, is one of the major biotic stress-oriented diseases that adversely affect the rice productivity worldwide. However, the regulatory mechanisms are not understood yet comprehensively. In the current study, we had investigated the potential roles of miRNAs in economically important indica rice variety Pusa Basmati-1 upon R. solani infection by carrying out in-depth, high-throughput small RNA sequencing with a total data size of 435 million paired-end raw reads from rice leaf RNA samples collected at different time points. Detailed data analysis revealed a total of 468 known mature miRNAs and 747 putative novel miRNAs across all the libraries. Target prediction and Gene Ontology functional analysis of these miRNAs were found to be unraveling various cellular, molecular, and biological functions by targeting various plant defense-related genes. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to validate the miRNAs and their putative target genes. Out of the selected miRNA-specific putative target genes, miR395a binding and its cleavage site on pentatricopeptide were determined by 5’ RACE-PCR. It might be possible that R. solani instigated chloroplast degradation by modulating the pentatricopeptide which led to increased susceptibility to fungal infection.

Covalently closed circular RNAs are neoteric to the eukaryotic family of long non-coding RNAs emerging as a result of 5′–3′ backsplicing from exonic, intronic, or intergenic regions spanning the parental gene. Owing to their unique structure and stability, circular RNAs have a multitude of functional properties such as micro-RNA and protein sponges, direct and indirect modulators of gene expression, protein translation, and many unproven activities apart from being potential biomarkers. However, due to their low abundance, most of the global circular RNA identification is carried out by high-throughput NGS-based approaches requiring millions of sequencing reads. This lag in methodological advancements demands for newer, more refined, and efficient identification techniques. Here, we aim to show an improved version of our previously reported template-dependent multiple displacement amplification (tdMDA)-NGS method by superimposing the ribosomal depletion step and use of H minus reverse transcriptase and RNase H. Implication of tdMDA using highly replicative Phi29 DNA polymerase after minimizing the linear and ribosomal RNA content further intensifies its detection limit toward even the abysmally expressing circular RNA at a low NGS depth, thereby decreasing the cost of identifying a single circular RNA. A >11-fold and >6-fold increase in total circular RNA was identified from the improved-tdMDA-NGS method over the traditional method of circRNA sequencing using DCC and CIRI2 pipelines, respectively, from Oryza sativa subsp. Indica. Furthermore, the reliability of the improved-tdMDA-NGS method was also asserted in HeLa cell lines, showing a significant fold difference in comparison with the existing traditional method of circRNA sequencing. Among the identified circular RNAs, a significant percentage from both rice (∼58%) and HeLa cell lines (∼84%) is found to be matched with the previously reported circular RNAs, suggesting that the improved-tdMDA-NGS method can be adapted to detect and characterize the circular RNAs from different biological systems.

Sheath blight (ShB) disease, caused by

With the innovative knowledge and bioinformatics tools in the identification and characterization of noncoding RNAs, circular RNA (circRNA) is added as a new member to the noncoding RNAs family. CircRNA enrichment by rRNA depletion/RNase R or poly-A removal/RNase R treatment followed by NGS analysis is the most frequently adopted method for circular RNA identification and characterization. In this chapter, we describe the multiple displacement amplification (MDA) as a convenient method to augment the identification of even the abysmally expressed circular RNAs at low sequencing depth. Total RNA, extracted at three different developmental stages of rice, is subjected to RiboMinus and RNase R treatment to deplete the linear RNAs. The enriched circular RNAs are reverse transcribed with random hexamers. The resulting cDNA is subjected to phi29 DNA polymerase amplification using exo-resistant random pentamers to yield high molecular weight dsDNA product, followed by Illumina sequencing at ten million paired end reads per sample. The sequence analysis yielded a promising number of circRNAs with the appreciable inclusion of differentially regulated and minimally expressed circRNAs at a comparatively reduced cost.

Circular RNA (CircRNA) is yet another vital addition to the noncoding RNA family. They are mainly derived by fusion of downstream 3' splice donor with upstream 5' splice acceptor by a noncanonical form of alternative splicing mechanism called backsplicing. An array of functional aspects of these circRNAs has been reported in animal systems. However, functional investigation of circRNA in plants is very limited. In this chapter, we described a methodological outline to study the circRNA biogenesis and to characterize its function(s). Sequence of a newly identified Oryza sativa Indica circRNA flanked by complementary repeat sequences of a rice intron was assembled to yield a circRNA expression cassette. This cassette can be cloned into any plant expression vector which has a suitable promoter (CaMV 35S or ubiquitin promoter) and terminator, and can be used for any circRNA-mediated functional studies. Subsequent agroinfection of rice calli with this cassette yielded circRNA expressing transgenic plants. These transgenic plants were used to establish a correlation between the expressing circRNA, parental gene, and interacting miRNAs. Moreover, effect of circRNA overexpression on plant phenotype under various stress conditions can be studied using these transgenic plants. Also, RNA pull-down assay can be performed to identify the circRNA interacting proteins and the expression of these RBPs can also be studied from these transgenic plants.

With the innovative knowledge and bioinformatics tools in the identification and characterization of noncoding RNAs, circular RNA (circRNA) is added as a new member to the noncoding RNAs family. CircRNA enrichment by rRNA depletion/RNase R or poly-A removal/RNase R treatment followed by NGS analysis is the most frequently adopted method for circular RNA identification and characterization. In this chapter, we describe the multiple displacement amplification (MDA) as a convenient method to augment the identification of even the abysmally expressed circular RNAs at low sequencing depth. Total RNA, extracted at three different developmental stages of rice, is subjected to RiboMinus and RNase R treatment to deplete the linear RNAs. The enriched circular RNAs are reverse transcribed with random hexamers. The resulting cDNA is subjected to phi29 DNA polymerase amplification using exo-resistant random pentamers to yield high molecular weight dsDNA product, followed by Illumina sequencing at ten million paired end reads per sample. The sequence analysis yielded a promising number of circRNAs with the appreciable inclusion of differentially regulated and minimally expressed circRNAs at a comparatively reduced cost.

Circular RNA (CircRNA) is yet another vital addition to the noncoding RNA family. They are mainly derived by fusion of downstream 3' splice donor with upstream 5' splice acceptor by a noncanonical form of alternative splicing mechanism called backsplicing. An array of functional aspects of these circRNAs has been reported in animal systems. However, functional investigation of circRNA in plants is very limited. In this chapter, we described a methodological outline to study the circRNA biogenesis and to characterize its function(s). Sequence of a newly identified Oryza sativa Indica circRNA flanked by complementary repeat sequences of a rice intron was assembled to yield a circRNA expression cassette. This cassette can be cloned into any plant expression vector which has a suitable promoter (CaMV 35S or ubiquitin promoter) and terminator, and can be used for any circRNA-mediated functional studies. Subsequent agroinfection of rice calli with this cassette yielded circRNA expressing transgenic plants. These transgenic plants were used to establish a correlation between the expressing circRNA, parental gene, and interacting miRNAs. Moreover, effect of circRNA overexpression on plant phenotype under various stress conditions can be studied using these transgenic plants. Also, RNA pull-down assay can be performed to identify the circRNA interacting proteins and the expression of these RBPs can also be studied from these transgenic plants.

Regulation of gene expression in any biological system is a complex process with many checkpoints at the transcriptional, post-transcriptional and translational levels. The control mechanism is mediated by various protein factors, secondary metabolites and a newly included regulatory member, i.e., noncoding RNAs (ncRNAs). It is known that ncRNAs modulate the mRNA or protein profiles of the cell depending on the degree of complementary and context of the microenvironment. In plants, ncRNAs are essential for growth and development in normal conditions by controlling various gene expressions and have emerged as a key player to guard plants during adverse conditions. In order to have smooth functioning of the plants under any environmental pressure, two very important DNA-harboring semi-autonomous organelles, namely, chloroplasts and mitochondria, are considered as main players. These organelles conduct the most crucial metabolic pathways that are required to maintain cell homeostasis. Thus, it is imperative to explore and envisage the molecular machineries responsible for gene regulation within the organelles and their coordination with nuclear transcripts. Therefore, the present review mainly focuses on ncRNAs origination and their gene regulation in chloroplasts and plant mitochondria.

N6-methyladenine (6mA) is a DNA base modification at the 6th nitrogen position; recently, it has been resurfaced as a potential reversible epigenetic mark in eukaryotes. Despite its existence, 6mA was considered to be absent due to its undetectable level. However, with the new advancements in methods, considerable 6mA distribution is identified across the plant genome. Unlike 5-methylcytosine (5mC) in the gene promoter, 6mA does not have a definitive role in repression but is exposed to have divergent regulation in gene expression. Though 6mA information is less known, the available evidences suggest its function in plant development, tissue differentiation, and regulations in gene expression. The current review article emphasizes the research advances in DNA 6mA modifications, identification, available databases, analysis tools and its significance in plant development, cellular functions and future perspectives of research.

Geminiviridae is a large family of circular, single stranded DNA viruses, which infects and causes devastating diseases on economically important crops. They are subdivided into nine genera. Members of the genus begomovirus encode a pathogenic protein called AC2/C2 which interacts that inactivates many plant proteins and trans-activates a number of host genes via the C-terminal transactivation domain. Hence, a sequence analysis on C-terminal region of AC2/C2 was completed. Analysis of 124 bipartite and 463 mono partite begomo viral AC2/C2 proteins revealed major differences in protein length, composition and position of acidic, aromatic and hydrophobic residues. Secondary structure analysis of AC2/C2 revealed the possible formation of C-terminal α-helix, which is similar to the acidic activation domain of many transcriptional activator proteins. Previous studies demonstrated that AC2 utilizes conserved late element (CLE) for the transactivation of viral genes and genome-wide mapping of same consensus in A. thaliana yielded 122 promoters with exact CLE consensus sequence. Analysis of protein interaction network for 106 CLE containing genes, 87 AC2 trans activated genes and 10 AC2 interacting proteins revealed a possible regulation of hundreds of host proteins which helps begomoviruses to produce a successful viral infection.

N6-methyladenine (6mA) is a DNA base modification at the 6th nitrogen position; recently, it has been resurfaced as a potential reversible epigenetic mark in eukaryotes. Despite its existence, 6mA was considered to be absent due to its undetectable level. However, with the new advancements in methods, considerable 6mA distribution is identified across the plant genome. Unlike 5-methylcytosine (5mC) in the gene promoter, 6mA does not have a definitive role in repression but is exposed to have divergent regulation in gene expression. Though 6mA information is less known, the available evidences suggest its function in plant development, tissue differentiation, and regulations in gene expression. The current review article emphasizes the research advances in DNA 6mA modifications, identification, available databases, analysis tools and its significance in plant development, cellular functions and future perspectives of research.

Circular RNAs are the most recent addition in the non-coding RNA family, which has started to gain recognition after a decade of obscurity. The first couple of reports that emerged at the beginning of this decade and the amount of evidence that has accumulated thereafter has, however, encouraged RNA researchers to navigate further in the quest for the exploration of circular RNAs. The joining of 5' and 3' ends of RNA molecules through backsplicing forms circular RNAs during co-transcriptional or post-transcriptional processes. These molecules are capable of effectively sponging microRNAs, thereby regulating the cellular processes, as evidenced by numerous animal and plant systems. Preliminary studies have shown that circular RNA has an imperative role in transcriptional regulation and protein translation, and it also has significant therapeutic potential. The high stability of circular RNA is rendered by its closed ends; they are nevertheless prone to degradation by circulating endonucleases in serum or exosomes or by microRNA-mediated cleavage due to their high complementarity. However, the identification of circular RNAs involves diverse methodologies and the delineation of its possible role and mechanism in the regulation of cellular and molecular architecture has provided a new direction for the continuous research into circular RNA. In this review, we discuss the possible mechanism of circular RNA biogenesis, its structure, properties, degradation, and the growing amount of evidence regarding the detection methods and its role in animal and plant systems.

The economically important crops such as cotton, potato, tomato, etc. are infected by various plant viruses and pose major limitations for the production. Plant viral diseases are difficult to manage; it is strongly advised to use insecticides to eradicate the viral pathogens. Alternatively, implementation of virus-free source materials or selection of disease-resistant plants has been recommended. However, above approaches often result in failure, and scientist has proposed the concept of pathogen-derived resistance (PDR) which accelerated the research to acquire virus resistance plant through genetic engineering. Genetic engineering approaches are highly beneficial to confer and control the viral diseases in a wide range of crops. Compared to traditional breeding methods, genetic engineering offers precise and rapid technology to attain the virus-resistant plants. The mechanism behind the PDR can be a protein- or nucleic acid-mediated pathway. Based on available results, it has been observed that protein-mediated resistance confers reasonable protection against wide variety of related viruses while nucleic acid-mediated resistance provides an optimum level of protection which is only against specific virus or closely related strains of a virus. Coat protein-mediated protection has been reported for Papaya ringspot virus, Tobacco mosaic virus, Cucumber mosaic virus, Alfalfa mosaic virus, Potato virus X, Potato virus Y and Potato leaf roll virus. In addition, sequences from the viral replicase gene, defective virus movement protein genes and virus antisense RNA have been engineered into plants to obtain virus resistance. This chapter is devoted to the comprehensive description of the various strategies used to produce virus-resistant plants.

Circular RNAs (circRNAs) are newly discovered incipient non-coding RNAs with potential roles in disease progression in living organisms. Significant reports, since their inception, highlight the abundance and putative functional roles of circRNAs in every organism checked for, likeO. sativa,Arabidopsis, human, and mouse. CircRNA expression is generally less than their linear mRNA counterparts which fairly explains the competitive edge of canonical splicing over non-canonical splicing. However, existing methods may not be sensitive enough for the discovery of low-level expressed circRNAs. By combining template-dependent multiple displacement amplification (tdMDA), Illumina sequencing, and bioinformatics tools, we have developed an experimental protocol that is able to detect 1,875 novel and known circRNAs fromO. sativa. The same method also revealed 9,242 putative circRNAs in less than 40 million reads for the first time from theNicotiana benthamianawhose genome has not been fully annotated. Supported by the PCR-based validation and Sanger sequencing of selective circRNAs, our method represents a valuable tool in profiling circRNAs from the organisms with or without genome annotation.

Background and Purpose— Social isolation increases mortality and impairs recovery after stroke in clinical populations. These detrimental effects have been recapitulated in animal models, although the exact mechanism mediating these effects remains unclear. Dysregulation of microRNAs (miRNAs) occurs in both strokes as well as after social isolation, which trigger changes in many downstream genes. We hypothesized that miRNA regulation is involved in the detrimental effects of poststroke social isolation in aged animals. Methods— We pair-housed 18-month-old C57BL/6 male mice for 2 weeks before a 60-minute right middle cerebral artery occlusion or sham surgery and then randomly assigned mice to isolation or continued pair housing immediately after surgery. We euthanized mice either at 3, 7, or 15 days after surgery and isolated the perilesional frontal cortex for whole microRNAome analysis. In an additional cohort, we treated mice 1 day after stroke onset with an in vivo-ready antagomiR-141 for 3 days. Results— Using whole microRNAome analysis of 752 miRNAs, we identified miR-141-3p as a unique miRNA that was significantly upregulated in isolated mice in a time-dependent manner up to 2 weeks after stroke. Posttreatment with an antagomiR-141-3p reduced the postisolation-induced increase in miR-141-3p to levels almost equal to those of pair-housed stroke controls. This treatment significantly reduced mortality (by 21%) and normalized infarct volume and neurological scores in poststroke-isolated mice. Quantitative PCR analysis revealed a significant upregulation of Tgfβr1 (transforming growth factor beta receptor 1, a direct target of miR-141-3p) and Igf-1 (insulin-like growth factor 1) mRNA after treatment with antagomiR. Treatment also increased the expression of other pleiotropic cytokines such as Il-6 (interleukin 6) and Tnf-α (tumor necrosis factor-α), an indirect or secondary target) in brain tissue. Conclusions— miR-141-3p is increased with poststroke isolation. Inhibition of miR-141-3p improved mortality, neurological deficits, and decreased infarct volumes. Importantly, these therapeutic effects occurred in aged animals, the population most at risk for stroke and poststroke isolation.

Long considered to be active only in germline, PIWI/piRNA pathway is now known to play significant role in somatic cells, especially neurons. Nonetheless, so far there is no evidence for the presence of piRNAs in the neurosensory retina. In this study, we have uncovered 102 piRNAs in human retina and retinal pigment epithelium (RPE) by analysing RNA-seq data. The identified piRNAs were enriched with three motifs predicted to be involved in rRNA processing and sensory perception. Further, expression of piRNAs in donor eyes were assessed by qRT-PCR. Loss of piRNAs in HIWI2 knockdown ARPE19 cells downregulated targets implicated in intracellular transport (SNAREs andRabs), circadian clock (TIMELESS) and retinal degeneration (LRPAP1andRPGRIP1). Moreover, piRNAs were dysregulated under oxidative stress indicating their potential role in retinal pathology. Intriguingly, computational analysis revealed complete and partial seed sequence similarity between piR-62011 and sensory organ specific miR-183/96/182 cluster. Furthermore, the expression of retina enriched piR-62011 positively correlated with miR-182 in HIWI2 silenced Y79 cells. Thus, our data provides an evidence for the expression of piRNAs in human retina and RPE. Collectively, our work demonstrates that piRNAs dynamically regulate distinct molecular events in the maintenance of retinal homeostasis.

Yellow vein mosaic or yellow leaf curl disease in tomato, okra and other pulses is transmitted by Bemisia tabaci (White fly), leading to loss of production and quality. Gene silencing is one of the powerful approaches to overcome viral based plant diseases. However it is of great challenge to design potential small interfering RNA (siRNA) molecules against genes responsible for the diseases. From the primary sequence information, using insilico approach, 15 siRNAs were designed for genes involved in pathogenicity like suppressor, movement and nuclear shuttle namely V2, C2 and C4 of monopartite genome and BC1 and BV1 of bipartite genome from the Geminiviridae family. Short listing based on ranking score, GC content, base pairs, secondary structure identified 2 siRNAs for V2, 1 siRNAs for C2 and 2 siRNAs for C4, 5 siRNAs for BV1 and 5 siRNAs for BC1 genes.

Background and Purpose— Circular RNAs (circRNAs) are a novel class of noncoding RNAs formed from many protein-coding genes by backsplicing. Although their physiological functions are not yet completely defined, they are thought to control transcription, translation, and microRNA levels. We investigated whether stroke changes the circRNAs expression profile in the mouse brain. Methods— Male C57BL/6J mice were subjected to transient middle cerebral artery occlusion, and circRNA expression profile was evaluated in the penumbral cortex at 6, 12, and 24 hours of reperfusion using circRNA microarrays and real-time PCR. Bioinformatics analysis was conducted to identify microRNA binding sites, transcription factor binding, and gene ontology of circRNAs altered after ischemia. Results— One thousand three-hundred twenty circRNAs were expressed at detectable levels mostly from exonic (1064) regions of the genes in the cerebral cortex of sham animals. Of those, 283 were altered (>2-fold) at least at one of the reperfusion time points, whereas 16 were altered at all 3 time points of reperfusion after transient middle cerebral artery occlusion compared with sham. Postischemic changes in circRNAs identified by microarray analysis were confirmed by real-time PCR. Bioinformatics showed that these 16 circRNAs contain binding sites for many microRNAs. Promoter analysis showed that the circRNAs altered after stroke might be controlled by a set of transcription factors. The major biological and molecular functions controlled by circRNAs altered after transient middle cerebral artery occlusion are biological regulation, metabolic process, cell communication, and binding to proteins, ions, and nucleic acids. Conclusions— This is a first study that shows that stroke alters the expression of circRNAs with possible functional implication to poststroke pathophysiology.

MicroRNAs (miRNAs) are crucial regulatory RNAs, originated from hairpin precursors. For the past decade, researchers have been focusing extensively on miRNA profiles in various plants. However, there have been few studies on the global profiling of precursor miRNAs (pre-miRNAs), even in model plants. Here, for the first time in a non-model plant-Abelmoschus esculentus with negligible genome information-we are reporting the global profiling to characterize the miRNAs and their associated pre-miRNAs by applying a next generation sequencing approach. Preliminarily, we performed small RNA (sRNA) sequencing with five biological replicates of leaf samples to attain 207,285,863 reads; data analysis using miRPlant revealed 128 known and 845 novel miRNA candidates. With the objective of seizing their associated hairpin precursors, we accomplished pre-miRNA sequencing to attain 83,269,844 reads. The paired end reads are merged and adaptor trimmed, and the resulting 40-241 nt (nucleotide) sequences were picked out for analysis by using perl scripts from the miRGrep tool and an in-house built shell script for Minimum Fold Energy Index (MFEI) calculation. Applying the stringent criteria of the Dicer cleavage pattern and the perfect stem loop structure, precursors for 57 known miRNAs of 15 families and 18 novel miRNAs were revealed. Quantitative Real Time (qRT) PCR was performed to determine the expression of selected miRNAs.

MicroRNAs (miRNAs) are crucial regulatory RNAs, originated from hairpin precursors. For the past decade, researchers have been focusing extensively on miRNA profiles in various plants. However, there have been few studies on the global profiling of precursor miRNAs (pre-miRNAs), even in model plants. Here, for the first time in a non-model plant—Abelmoschus esculentus with negligible genome information—we are reporting the global profiling to characterize the miRNAs and their associated pre-miRNAs by applying a next generation sequencing approach. Preliminarily, we performed small RNA (sRNA) sequencing with five biological replicates of leaf samples to attain 207,285,863 reads; data analysis using miRPlant revealed 128 known and 845 novel miRNA candidates. With the objective of seizing their associated hairpin precursors, we accomplished pre-miRNA sequencing to attain 83,269,844 reads. The paired end reads are merged and adaptor trimmed, and the resulting 40–241 nt (nucleotide) sequences were picked out for analysis by using perl scripts from the miRGrep tool and an in-house built shell script for Minimum Fold Energy Index (MFEI) calculation. Applying the stringent criteria of the Dicer cleavage pattern and the perfect stem loop structure, precursors for 57 known miRNAs of 15 families and 18 novel miRNAs were revealed. Quantitative Real Time (qRT) PCR was performed to determine the expression of selected miRNAs.

The Akt signalling pathway is a crucial network of proteins, which plays a role in neonatal cellular proliferation, hypertrophy and cellular survival mechanism in the heart through a multifaceted system including, small non-coding RNAs (sncRNAs). Despite numerous reports on the distorted expression of these proteins in various cardiovascular diseases, this review focuses on the role of miRNA and piRNA in altering Akt signalling. Nevertheless the role of these sncRNAs in the Akt pathway needs to be studied in detail, there are evidence indicating that they can play a vital function in Akt-mediated cardiac survival. Recent reports indicate that, modification of such miRNA/piRNA causes alteration in the Akt pathway during both physiology and pathology. Therefore, understanding the antisense mediated molecular mechanisms of Akt pathway can devise a new vision towards biomarkers and therapeutic approaches to various cardiovascular diseases.

Bhendi yellow vein mosaic virus (BYVMV) belongs to the monopartite begomovirus associated with the &beta, satellite. As a single-stranded DNA (ssDNA) virus, it should be amenable to transcriptional and post-transcriptional gene silencing (TGS and PTGS). Previously, we had demonstrated C2, C4 and &beta, C1 to be having different levels of influence on PTGS. Hence in the present study, a series of experiments such as agroinfiltration, chop-polymerase chain reaction (PCR), quantitative PCR (qPCR) and bisulfite next generation sequencing (NGS) were designed to analyse the involvement of BYVMV proteins on DNA methylation suppression. From the preliminary studies, we concluded that BYVMV genes were responsible for TGS suppression and C2, C4 genes from BYVMV were selected for further studies. Agroinfiltration experiments with mutant C2 and C4 partial tandem repeat (PTR) constructs of BYVMV have confirmed the role of C2 and C4 in DNA methylation impairment. The protoplast replication assay has shown that C4 was not an impediment for viral DNA replication and subsequent agroinfiltration studies with the C4 mutant BYVMV PTR construct have revealed the involvement of C4 in viral DNA movement.

We examined the microRNA profiles of Glioblastoma stem (CD133+) and non-stem (CD133-) cell populations and found up-regulation of several miRs in the CD133- cells, including miR-451, miR-486, and miR-425, some of which may be involved in regulation of brain differentiation. Transfection of GBM cells with the above miRs inhibited neurosphere formation and transfection with the mature miR-451 dispersed neurospheres, and inhibited GBM cell growth. Furthermore, transfection of miR-451 combined with Imatinib mesylate treatment had a cooperative effect in dispersal of GBM neurospheres. In addition, we identified a target site for SMAD in the promoter region of miR-451 and showed that SMAD3 and 4 activate such a promoter-luciferase construct. Transfection of SMAD in GBM cells inhibited their growth, suggesting that SMAD may drive GBM stem cells to differentiate to CD133- cells through up-regulation of miR-451 and reduces their tumorigenicity. Identification of additional miRs and target genes that regulate GBM stem cells may provide new potential drugs for therapy.

MicroRNAs (miRNAs) are known to repress translation by binding to the 3'UTRs of mRNAs. Using bioinformatics, we recently reported that several miRNAs also have target sites in DNA particularly in the promoters of the protein-coding genes. To understand the functional significance of this phenomenon, we tested the effects of miR-324-3p binding to RelA promoter. In PC12 cells, co-transfection with premiR-324-3p induced a RelA promoter plasmid in a dose-dependent manner and this effect was lost when the miR-324-3p binding site in the promoter was mutated. PremiR-324-3p transfection also significantly induced the endogenous RelA mRNA and protein expression in PC12 cells. Furthermore, transfection with premiR-324-3p increased the levels of cleaved caspase-3 which is a marker of apoptosis. Importantly, the miR-324-3p effects were Ago2 mediated as Ago2 knockdown prevented RelA expression and cleavage of caspase-3. Thus, our studies show that miRNA-mediated transcriptional activation can be seen in PC12 cells which are neural in origin.

Recent studies showed that stroke extensively alters cerebral microRNA (miRNA) expression profiles and several miRNAs play a role in mediating ischemic pathophysiology. We currently evaluated the significance of miR-29c, a highly expressed miRNA in rodent brain that was significantly down-regulated after focal ischemia in adult rats as well as after oxygen-glucose deprivation in PC12 cells. Bioinformatics indicated that DNA methyltransferase 3a (DNMT3a) is a major target of miR-29c and co-transfection with premiR-29c prevented DNMT3a 3'UTR vector expression. In PC12 cells, treatment with premiR-29c prevented OGD-induced cell death (by 58 ± 6%; p