Double-stranded RNA (dsRNA) is associated with most viral infections - it either constitutes the viral genome (in the case of dsRNA viruses) or is generated in host cells during viral replication. ...Hence, nearly all organisms have the capability of recognizing dsRNA and mounting a response, the primary aim of which is to mitigate the potential infection. In vertebrates, a set of innate immune receptors for dsRNA induce a multitude of cell-intrinsic and cell-extrinsic immune responses upon dsRNA recognition. Notably, recent studies showed that vertebrate cells can accumulate self-derived dsRNAs or dsRNA-like species upon dysregulation of several cellular processes, activating the very same immune pathways as in infected cells. On the one hand, such aberrant immune activation in the absence of infection can lead to pathogenesis of immune disorders, such as Aicardi-Goutières syndrome. On the other hand, the same innate immune reaction can be induced in a controlled setting for a therapeutic benefit, as occurs in immunotherapies. In this Review, we describe mechanisms by which immunostimulatory dsRNAs are generated in mammalian cells, either by viruses or by the host cells, and how cells respond to them, with the focus on recent developments regarding the role of cellular dsRNAs in immune modulation.
Long noncoding RNAs (lncRNAs) are emerging as critical regulators of gene expression in the immune system. Studies have shown that lncRNAs are expressed in a highly lineage-specific manner and ...control the differentiation and function of innate and adaptive cell types. In this Review, we focus on mechanisms used by lncRNAs to regulate genes encoding products involved in the immune response, including direct interactions with chromatin, RNA and proteins. In addition, we address new areas of lncRNA biology, such as the functions of enhancer RNAs, circular RNAs and chemical modifications to RNA in cellular processes. We emphasize critical gaps in knowledge and future prospects for the roles of lncRNAs in the immune system and autoimmune disease.
Over the past several decades, much has been revealed about the nature of the host innate immune response to microorganisms, with the identification of pattern recognition receptors (PRRs) and ...pathogen-associated molecular patterns, which are the conserved microbial motifs sensed by these receptors. It is now apparent that these same PRRs can also be activated by non-microbial signals, many of which are considered as damage-associated molecular patterns. The sterile inflammation that ensues either resolves the initial insult or leads to disease. Here, we review the triggers and receptor pathways that result in sterile inflammation and its impact on human health.
The mammalian intestine is colonized by trillions of microorganisms, most of which are bacteria that have co-evolved with the host in a symbiotic relationship. The collection of microbial populations ...that reside on and in the host is commonly referred to as the microbiota. A principal function of the microbiota is to protect the intestine against colonization by exogenous pathogens and potentially harmful indigenous microorganisms via several mechanisms, which include direct competition for limited nutrients and the modulation of host immune responses. Conversely, pathogens have developed strategies to promote their replication in the presence of competing microbiota. Breakdown of the normal microbial community increases the risk of pathogen infection, the overgrowth of harmful pathobionts and inflammatory disease. Understanding the interaction of the microbiota with pathogens and the host might provide new insights into the pathogenesis of disease, as well as novel avenues for preventing and treating intestinal and systemic disorders.
A dense resident microbial community in the gut, referred as the commensal microbiota, coevolved with the host and is essential for many host physiological processes that include enhancement of the ...intestinal epithelial barrier, development of the immune system and acquisition of nutrients. A major function of the microbiota is protection against colonization by pathogens and overgrowth of indigenous pathobionts that can result from the disruption of the healthy microbial community. The mechanisms that regulate the ability of the microbiota to restrain pathogen growth are complex and include competitive metabolic interactions, localization to intestinal niches and induction of host immune responses. Pathogens, in turn, have evolved strategies to escape from commensal-mediated resistance to colonization. Thus, the interplay between commensals and pathogens or indigenous pathobionts is critical for controlling infection and disease. Understanding pathogen-commensal interactions may lead to new therapeutic approaches to treating infectious diseases.
Circular RNAs (circRNAs) are a diverse class of RNAs with varying sizes, cellular abundance, and biological functions. Investigations from the past decade have revealed that circRNAs are ubiquitously ...found in eukaryotes and have defined the different biological roles of circRNAs to illuminate this previously unrecognized class of molecules. In the context of the immune system, immune responses and immune-related diseases alter circRNA expression. More recently, several oncogenic double-stranded DNA viruses have been found to encode circRNAs. In this review, we summarize the current understanding of circRNAs and their emerging functions in immune regulation and autoimmune disorders, and discuss the identification and potential roles of viral circRNAs during infections. Finally, we present promising areas for future investigations in the nascent field of circRNAs.
Circular RNAs (circRNAs) are a recently identified class of ubiquitously expressed RNAs found in eukaryotes, archaea, and viruses.DNA viruses Kaposi's sarcoma-associated herpesvirus, Epstein–Barr virus, and human papillomavirus encode circRNAs. Some circRNAs possess pro-viral functions as miRNA sponges and templates for translation.CircRNAs are differentially expressed in immune cells and in autoimmune diseases, including rheumatoid arthritis and systemic lupus erythematosus.Emerging data suggest that circRNAs have biological roles in the immune system as transcriptional regulators, protein sponges, and templates for translation.
Less is more: A minimalist “clickable” photo‐crosslinker (see scheme) was incorporated with numerous small‐molecule kinase inhibitors. The resulting probes were used for both in vitro (cell lysates) ...and in situ (live cells) proteome profiling, for large‐scale identification of their potential cellular kinase targets and shows improved outcomes over previous probes.
The switch from mitosis to meiosis is the key event marking onset of differentiation in the germline stem cell lineage. In
, the translational repressor Bgcn is required for spermatogonia to stop ...mitosis and transition to meiotic prophase and the spermatocyte state. Here we show that the mammalian Bgcn homolog YTHDC2 facilitates a clean switch from mitosis to meiosis in mouse germ cells, revealing a conserved role for YTHDC2 in this critical cell fate transition. YTHDC2-deficient male germ cells enter meiosis but have a mixed identity, maintaining expression of Cyclin A2 and failing to properly express many meiotic markers. Instead of continuing through meiotic prophase, the cells attempt an abnormal mitotic-like division and die. YTHDC2 binds multiple transcripts including
and other mitotic transcripts, binds specific piRNA precursors, and interacts with RNA granule components, suggesting that proper progression of germ cells through meiosis is licensed by YTHDC2 through post-transcriptional regulation.
•Diverse methodologies exist to produce circRNAs both in vitro and in vivo.•Methods for artificial circRNA synthesis in vivo resemble natural circRNA biogenesis.•Artificial circRNAs can be customized ...to carry out desired functions in cells.
Circular RNAs (circRNAs) are a novel class of RNAs distinguished by their single-stranded, covalently-closed topology. Although initially perceived as rare byproducts of aberrant splicing, circRNAs are now recognized as ubiquitously expressed and functionally significant. These discoveries have led to a growing need for ways to model circRNAs in living cells to advance our understanding of their biogenesis, regulation, and function, and to adopt them as new technologies for application within research and medicine. In this review, we provide an updated summary of approaches used to produce circRNAs in vitro and in vivo, the latter of which has grown considerably in recent years. Given increased interest in the unique functions carried out by individual circRNAs, we further dedicate a section on how to customize synthesized circRNAs for specific biological roles. We focus on the most common applications, including designing circRNAs for protein delivery, to target miRNAs and proteins, to act as fluorescent reporters, and to modulate cellular immunity.
Protein kinases (PKs) play an important role in the development and progression of cancer by regulating cell growth, survival, invasion, metastasis, and angiogenesis. Dasatinib (BMS-354825), a dual ...Src/Abl inhibitor, is a promising therapeutic agent with oral bioavailability. It has been used for the treatment of imatinib-resistant chronic myelogenous leukemia (CML). Most kinase inhibitors, including Dasatinib, inhibit multiple cellular targets and do not possess exquisite cellular specificity. Recent efforts in kinase research thus focus on the development of large-scale, proteome-wide chemical profiling methods capable of rapid identification of potential cellular (on- and off-) targets of kinase inhibitors. Most existing approaches, however, are still problematic and in many cases not compatible with live-cell studies. In this work, we have successfully developed a cell-permeable kinase probe (DA-2) capable of proteome-wide profiling of potential cellular targets of Dasatinib. In this way, highly regulated, compartmentalized kinase-drug interactions were maintained. By comparing results obtained from different proteomic setups (live cells, cell lysates, and immobilized affinity matrix), we found DA-2 was able to identify significantly more putative kinase targets. In addition to Abl and Src family tyrosine kinases, a number of previously unknown Dasatinib targets have been identified, including several serine/threonine kinases (PCTK3, STK25, eIF-2A, PIM-3, PKA C-α, and PKN2). They were further validated by pull-down/immunoblotting experiments as well as kinase inhibition assays. Further studies are needed to better understand the exact relevance of Dasatinib and its pharmacological effects in relation to these newly identified cellular targets. The approach developed herein should be amenable to the study of many of the existing reversible drugs/drug candidates.
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