Long noncoding RNAs (lncRNAs) have emerged as important regulators of diverse cellular processes, but their roles in the developing immune system are poorly understood. In this study, we analysed ...lncRNA expression during human B-cell development by array-based expression profiling of eleven distinct flow-sorted B-cell subsets, comprising pre-B1, pre-B2, immature, naive, memory, and plasma cells from bone marrow biopsies (n = 7), and naive, centroblast, centrocyte, memory, and plasmablast cells from tonsil tissue samples (n = 6), respectively. A remapping strategy was used to assign the array probes to 37630 gene-level probe sets, reflecting recent updates in genomic and transcriptomic databases, which enabled expression profiling of 19579 long noncoding RNAs, comprising 3947 antisense RNAs, 5277 lincRNAs, 7625 pseudogenes, and 2730 additional lncRNAs. As a first step towards inferring the functions of the identified lncRNAs in developing B-cells, we analysed their co-expression with well-characterized protein-coding genes, a method known as "guilt by association". By using weighted gene co-expression network analysis, we identified 272 lincRNAs, 471 antisense RNAs, 376 pseudogene RNAs, and 64 lncRNAs within seven sub-networks associated with distinct stages of B-cell development, such as early B-cell development, B-cell proliferation, affinity maturation of antibody, and terminal differentiation. These data provide an important resource for future studies on the functions of lncRNAs in development of the adaptive immune response, and the pathogenesis of B-cell malignancies that originate from distinct B-cell subpopulations.
All drugs perturb the expression of many genes in the cells that are exposed to them. These gene expression changes can be divided into effects resulting from engaging the intended target and effects ...resulting from engaging unintended targets. For antisense oligonucleotides, developments in bioinformatics algorithms, and the quality of sequence databases, allow oligonucleotide sequences to be analyzed computationally, in terms of the predictability of their interactions with intended and unintended RNA targets. Applying these tools enables selection of sequence-specific oligonucleotides where no- or only few unintended RNA targets are expected. To evaluate oligonucleotide sequence-specificity experimentally, we recommend a transcriptomics protocol where two or more oligonucleotides targeting the same RNA molecule, but with entirely different sequences, are evaluated together. This helps to clarify which changes in cellular RNA levels result from downstream processes of engaging the intended target, and which are likely to be related to engaging unintended targets. As required for all classes of drugs, the toxic potential of oligonucleotides must be evaluated in cell- and animal models before clinical testing. Since potential adverse effects related to unintended targeting are sequence-dependent and therefore species-specific, in vitro toxicology assays in human cells are especially relevant in oligonucleotide drug discovery.
•Locked nucleic acid-modified antisense oligonucleotides (LNAs) bind to and modulate RNA.•The high binding affinity of LNAs significantly improves potency.•Structural diversity of LNAs profoundly ...impact many drug properties besides potency.•Harnessing this diversity offers new opportunities for discovering LNA-based drugs.
Over the past 20 years, the field of RNA-targeted therapeutics has advanced based on discoveries of modified oligonucleotide chemistries, and an ever-increasing understanding of how to apply cellular assays to identify oligonucleotides with improved pharmacological properties in vivo. Locked nucleic acid (LNA), which exhibits high binding affinity and potency, is widely used for this purpose. Our understanding of RNA biology has also expanded tremendously, resulting in new approaches to engage RNA as a therapeutic target. Recent observations indicate that each oligonucleotide is a unique entity, and small structural differences between oligonucleotides can often lead to substantial differences in their pharmacological properties. Here, we outline new principles for drug discovery exploiting oligonucleotide diversity to identify rare molecules with unique pharmacological properties.
LNA-modified antisense oligonucleotides (LNAs) are widely used in RNA therapeutics. The structural diversity of LNAs affects most drug properties. Exploiting this diversity offers new opportunities for discovering LNA-based drugs.
In engineering applications, fluid-conveying pipes usually have geometric imperfections or initially curved configurations. Unlike the initially curved pipe supported at both ends, a slightly curved ...cantilevered pipe is capable of displaying some interesting behavior because it is a nonconservative system of fluid-structure interactions. In the present study, nonlinear static and dynamic behaviors of cantilevered pipes conveying fluid are explored, with four different initial shapes being considered. To this end, the strongly nonlinear governing equation is derived by employing the extended Lagrange equations written for dynamical systems containing non-material volumes. The static (steady) equilibrium configurations, stability, and nonlinear dynamics of the slightly curved cantilevered pipes are obtained with the aid of absolute nodal coordinate formulation (ANCF). Based on extensive numerical calculations, some interesting and sometimes unexpected results are displayed. The first unexpected feature in this dynamical system is that the flow-induced static deformation of the pipe can be extremely large even if the initial geometric imperfection of the pipe is quite small. The second unexpected result is that the critical flow velocity for flutter instability of the slightly curved pipe conveying fluid may be either lower or higher than that of a straight pipe, mainly depending on the static equilibrium configuration when the critical flow velocity is just reached. Moreover, it is demonstrated that the slightly curved pipe oscillates about the static equilibrium position instead of the initially curved centerline, and the preferred form of post-instability behavior is periodic motion within a wide range of system parameters considered.
RNase H cleaves RNA in RNA-DNA duplexes. It is present in all domains of life as well as in multiple viruses and is essential for mammalian development and for human immunodeficiency virus ...replication. Here, we developed a sequencing-based method to measure the cleavage of thousands of different RNA-DNA duplexes and thereby comprehensively characterized the sequence preferences of HIV-1, human and Escherichia coli RNase H enzymes. We find that the catalytic domains of E. coli and human RNase H have nearly identical sequence preferences, which correlate with the efficiency of RNase H-recruiting antisense oligonucleotides. The sequences preferred by HIV-1 RNase H are distributed in the HIV genome in a way suggesting selection for efficient RNA cleavage during replication. Our findings can be used to improve the design of RNase H-recruiting antisense oligonucleotides and show that sequence preferences of HIV-1 RNase H may have shaped evolution of the viral genome and contributed to the use of tRNA-Lys3 as primer during viral replication.
Antisense oligonucleotides (AONs) that promote degradation of complementary RNA are being developed as therapeutics. Here, we describe a simple computational workflow for identification of the ...regions on an RNA that are suitable for targeting with such AONs. The workflow is based on the statistical programming language R, and the calculations and data processing can be carried out on a desktop computer. Our workflow integrates well-established data resources and RNA structure-prediction tools and can be modified easily and expanded as new resources become available.
Reactive oxygen species (ROS) contribute to target-cell damage in inflammatory and iron-overload diseases. Little is known about iron transport regulation during inflammatory attack. Through a ...combination of in vitro and in vivo studies, we show that the proinflammatory cytokine IL-1β induces divalent metal transporter 1 (DMT1) expression correlating with increased β cell iron content and ROS production. Iron chelation and siRNA and genetic knockdown of DMT1 expression reduce cytokine-induced ROS formation and cell death. Glucose-stimulated insulin secretion in the absence of cytokines in Dmt1 knockout islets is defective, highlighting a physiological role of iron and ROS in the regulation of insulin secretion. Dmt1 knockout mice are protected against multiple low-dose streptozotocin and high-fat diet-induced glucose intolerance, models of type 1 and type 2 diabetes, respectively. Thus, β cells become prone to ROS-mediated inflammatory damage via aberrant cellular iron metabolism, a finding with potential general cellular implications.
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► IL-1 induces β cell iron uptake via DMT1, ROS formation, and apoptosis ► DMT1 deletion or iron chelation prevents β cell ROS formation and apoptosis ► Glucose-stimulated insulin secretion is decreased in DMT1 null islets ► DMT1 knockout improves β cell function in models of type 1 and type 2 diabetes
The pathogenesis of cutaneous T-cell lymphoma (CTCL) remains elusive. Recent discoveries indicate that the oncogenic microRNA miR-155 is overexpressed in affected skin from CTCL patients. Here, we ...address what drives the expression of miR-155 and investigate its role in the pathogenesis of CTCL. We show that malignant T cells constitutively express high levels of miR-155 and its host gene BIC (B cell integration cluster). Using ChIP-seq, we identify BIC as a target of transcription factor STAT5, which is aberrantly activated in malignant T cells and induced by IL-2/IL-15 in non-malignant T cells. Incubation with JAK inhibitor or siRNA-mediated knockdown of STAT5 decreases BIC/miR-155 expression, whereas IL-2 and IL-15 increase their expression in cell lines and primary cells. In contrast, knockdown of STAT3 has no effect, and BIC is not a transcriptional target of STAT3, indicating that regulation of BIC/miR-155 expression by STAT5 is highly specific. Malignant proliferation is significantly inhibited by an antisense-miR-155 as well as by knockdown of STAT5 and BIC.
In conclusion, we provide the first evidence that STAT5 drives expression of oncogenic BIC/miR-155 in cancer. Moreover, our data indicate that the STAT5/BIC/miR-155 pathway promotes proliferation of malignant T cells, and therefore is a putative target for therapy in CTCL.
The identification of molecules that can modulate RNA or protein function and the subsequent chemical and structural optimization to refine such molecules into drugs is a key activity in drug ...discovery. Here, we explored the extent to which chemical and structural differences in antisense oligonucleotides, designed as gapmers and capable of recruiting RNase H for target RNA cleavage, can affect their functional properties. To facilitate structure-activity learning, we analyzed two sets of iso-sequential locked nucleic acid (LNA)-modified gapmers, where we systematically varied the number and positions of LNA modifications in the flanks. In total, we evaluated 768 different and architecturally diverse gapmers in HeLa cells for target knockdown activity and cytotoxic potential and found widespread differences in both of these properties. Binding affinity between gapmer and RNA target, as well as the presence of certain short sequence motifs in the gap region, can explain these differences, and we propose statistical and machine-learning models that can be used to predict region-specific, optimal LNA-modification architectures. Once accessible regions in the target of interest have been identified, our results show how to refine and optimize LNA gapmers with improved pharmacological profiles targeting such regions.
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The successful development of high-affinity gapmer antisense oligonucleotide (ASO) therapeutics containing locked nucleic acid (LNA) or constrained ethyl (cEt) substitutions has been hampered by the ...risk of hepatotoxicity. Here, we present an in vitro approach using transfected mouse fibroblasts to predict the potential hepatic liabilities of LNA-modified ASOs (LNA-ASOs), validated by assessing 236 different LNA-ASOs with known hepatotoxic potential. This in vitro assay accurately reflects in vivo findings and relates hepatotoxicity to RNase H1 activity, off-target RNA downregulation, and LNA-ASO-binding affinity. We further demonstrate that the hybridization-dependent toxic potential of LNA-ASOs is also evident in different cell types from different species, which indicates probable translatability of the in vitro results to humans. Additionally, we show that the melting temperature (Tm) of LNA-ASOs maintained below a threshold level of about 55°C greatly diminished the hepatotoxic potential. In summary, we have established a sensitive in vitro screening approach for assessing the hybridization-dependent toxic potential of LNA-ASOs, enabling prioritization of candidate molecules in drug discovery and early development.
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