In the model plant Arabidopsis thaliana, four Dicer-like proteins (DCL1-4) mediate the production of various classes of small RNAs (sRNAs). Among these four proteins, DCL4 is by far the most versatile RNaseIII-like enzyme and previously identified dcl4 missense alleles were shown to uncouple the production of the various classes of DCL4-dependent sRNAs. Yet, little is known about the molecular mechanism pertaining this uncoupled production. Here, by studying the subcellular localization, interactome and binding to the sRNA precursors of three distinct dcl4 missense alleles, we simultaneously highlight the absolute requirement of its helicase domain for efficient production of all DCL4-dependent sRNAs, and identify an important determinant of DCL4 versatility within its PAZ domain that is mandatory for efficient processing of intramolecular foldback dsRNA precursors but dispensable for the production of siRNAs from RDR-dependent dsRNA susbtrates. This study not only provides novel insights into DCL4 mode of action in plants but also delineates interesting tools to further study the complexity of plant RNA silencing pathways. Overall design: RNA library of immunoprecipitated RNA from Col-0 (WT), pDCL4-DCL4-6:FHA/dcl4-2 and pDCL4-DCL4-8:FHA/dcl4-2 Arabidopsis flowers or seedlings were generated by deep sequencing, using Illumina HiSeq 2500 v4.
Characterization of DCL4 missense alleles provides insights into its ability to process distinct classes of dsRNA substrates.
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Natural killer (NK) cells are NKp46+CD3- lymphocytes that can perform granule-dependent cytotoxicity and produce interferon-gamma, when isolated from blood, lymphoid organs, lung, liver and uterus. Here we identify in dermis, gut lamina propria and cryptopatches, very distinct populations of NKp46+CD3- cells with reduced ability to degranulate and to produce interferon-gamma. In gut, the transcription factor RORgamma-t and CD127 (IL-7R alpha) defined a novel subset of NKp46+CD3- that is reminiscent of lymphoid tissue inducer (LTi)-like cells. Gut ROR gamma t+NKp46+ cells produced IL-22 in contrast to ROR-gamma t-independent lamina propria and dermis NK cells. These data show that LTi-like cells and NK cells share unanticipated similarities and reveal the heterogeneity of NKp46+CD3- cells in innate immunity, lymphoid organization and local tissue repair.
Influence of the transcription factor RORgammat on the development of NKp46+ cell populations in gut and skin.
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Aims/hypothesis Due to their ability to regulate various signalling pathways (cytokines, hormones, growth factors), the suppressor of cytokine signalling (SOCS) proteins are thought to be promising therapeutic targets for metabolic and inflammatory disorders. Hence, their role in vivo has to be precisely determined.
Constitutive expression of suppressor of cytokine signalling-3 in skeletal muscle leads to reduced mobility and overweight in mice.
Specimen part, SubjectView Samples
RNA-SEQ of mutants B cell for IgH 3''RR and Emu Overall design: CD43- splenic B-cells from wt, EÂµ-deficient or 3''RR deficient mice, non stimulated (NS) or stimulated (S) with 5mg/ml LPS.
E<sub>μ</sub> and 3'RR IgH enhancers show hierarchic unilateral dependence in mature B-cells.
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The IgH 3' regulatory region (3'RR) controls class switch recombination (CSR) and somatic hypermutation (SHM) in B cells. The mouse 3'RR contains four enhancer elements with hs1,2 flanked by inverted repeated sequences and the center of a 25-kb palindrome bounded by two hs3 enhancer inverted copies (hs3a and hs3b). hs4 lies downstream of the palindrome. Evolution maintained in mammals this unique palindromic arrangement suggesting that it is functionally significant. We report that deconstructing the palindromic IgH 3'RR strongly impacts its function even when enhancers are preserved. CSR and IgH transcription appear poorly dependent from the 3'RR architecture and are more or less preserved provided 3'RR enhancers are present. By contrast, an “architectural effect” significantly lowers VH germline transcription, AID recruitment and SHM. In conclusion, this work indicates that the IgH 3'RR does not simply pile up enhancer units but also optimally expose them into a functional architecture of crucial importance. Overall design: RNAseq analysis of B-cell splenocytes with (S=stimulated) or without (R=resting) LPS activation from wt, delta2leftPAL, and deltaIRIS mice.
Deciphering the importance of the palindromic architecture of the immunoglobulin heavy-chain 3' regulatory region.
Specimen part, Cell line, SubjectView Samples
Regulator of G protein signaling z1 (RGSz1), a member of the RGS family of proteins, is present in several networks expressing mu opioid receptors (MOPR). By using genetic mouse models for global or brain region-targeted manipulations of RGSz1 expression, we demonstrate that the suppression of RGSz1 function increases the analgesic efficacy of MOPR agonists in male and female mice and delays the development of morphine tolerance while decreasing the sensitivity to rewarding and locomotor activating effects. Using biochemical assays and next-generation RNA sequencing, we identified a key role of RGSz1 in the periaqueductal gray (PAG) in morphine tolerance. Chronic morphine administration promotes RGSz1 activity in the PAG, which in turn modulates transcription mediated by the Wnt/ß-catenin signaling pathway to promote analgesic tolerance to morphine. Conversely, the suppression of RGSz1 function stabilizes Axin2-Gaz complexes near the membrane and promotes ß-catenin activation, thereby delaying the development of analgesic tolerance. These data show that the regulation of RGS complexes, particularly those involving RGSz1-Gaz, represents a promising target for optimizing the analgesic actions of opioids without increasing the risk of dependence or addiction. Overall design: Understanding the impact of morphine tolerance and the influence of RGSz1 on gene expression in the PAG
Suppression of RGSz1 function optimizes the actions of opioid analgesics by mechanisms that involve the Wnt/β-catenin pathway.
Sex, Specimen part, Treatment, SubjectView Samples
FCRL4 is an immunoregulatory receptor that belongs to the Fc receptor-like (FCRL) family. In healthy individuals, this protein is specifically expressed by memory B cells (MBCs) and is preferentially localized in subephitelial regions of lymphoid tissues. An expansion of FCRL4+ B cells has been shown in blood or other tissues in various infectious or autoimmune pathologies. In the present work, we generated and characterized in vitro FCRL4+ B cells from purified MBCs using T-dependent and/or T-independent stimulation. FCRL4+ B cells account for 17% of cells generated at day-4 of culture. Transcriptomic and phenotypic analysis of FCRL4+ cells show that they are closely related to FCRL4+ tonsillar MBCs. Interestingly, these cells highly express inhibitory receptors genes as described for exhausted FCRL4+ MBCs in the blood of HIV-viremic individuals. In agreement, in vitro generated FCRL4+ B cells show a significant underexpression of cell cycle genes with a two fold weaker number of cell division compared to FCRL4- cells. Finally, resulting from their reduced proliferation and differentiation potential, we show that FCRL4+ cells are not prone to generate plasma cells, contrary to FCRL4- cells. Given the difficulty to access to in vivo FCRL4+ cells, our in vitro model could be of major interest to study the biology of normal and pathological FCRL4+ cells.
Characterization of human FCRL4-positive B cells.
Specimen partView Samples
Background: Arrhythmogenic cardiomyopathy (ACM) is a genetic autosomal disease characterized by abnormal cell-cell adhesion, cardiomyocyte death, progressive fibro-adipose replacement of the myocardium, arrhythmias and sudden death. Several different cell types contribute to the pathogenesis of ACM, including, as recently described, cardiac stromal cells (CStCs). In the present study, we aim to identify ACM-specific expression profiles of human CStCs derived from endomyocardial biopsies of ACM patients and healthy individuals employing TaqMan Low Density Arrays for miRNA expression profiling, and high throughput sequencing for gene expression quantification. Results: We identified 5 miRNAs and 272 genes as significantly differentially expressed. Both the differentially expressed genes as well as the target genes of the ACM-specific miRNAs were found to be enriched in cell adhesion related biological processes. Functional similarity and protein interaction based network analyses performed on the identified deregulated genes, miRNA targets and known ACM-causative genes revealed clusters of highly related genes involved in cell adhesion, extracellular matrix organization, lipid transport and ephrin receptor signaling. Conclusions: We determined for the first time the coding and non-coding transcriptome characteristic of ACM cardiac stromal cells, finding evidence for a potential contribution of miRNAs to ACM pathogenesis or phenotype maintenance. Besides known pathways, we identified also deregulation of genes encoding ephrin receptors and ephrins, thus suggesting a potential involvement of Eph-ephrin signaling in CStCs from ACM hearts. Overall design: Expression profiles of cardiac stromal cells from 3 ACM patients were compared against those of cardiac stromal cells from 3 healthy individuals.
The arrhythmogenic cardiomyopathy-specific coding and non-coding transcriptome in human cardiac stromal cells.
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To better understand the mechanistic basis of aging and its relationship with retinal degeneration, we examined gene expression changes in aging rod photoreceptors. Rod photoreceptor cell death is a feature of normal retinal aging and is accelerated in many retinal degenerative diseases, including AMD, the leading cause of untreatable adult blindness in the United States and other western countries. To our knowledge, the examination of age-related gene expression changes in a specific neuronal cell-type is novel, and it has allowed us to identify significant age-related changes with better resolution than is possible with whole retina samples. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR. Our results suggest that aging is progressive, beginning even in young adult mice. Although rod photoreceptors are highly specialized neurons, our analyses revealed changes in consensus pathways of aging, including oxidative phosphorylation and stress responses affecting transcription and inflammation. In addition, we identified stress response processes that may be especially relevant for the aging retina and retinal diseases, such as angiogenesis and nuclear receptor signaling pathways that affect retinoid and lipid metabolism.
Distinct signature of altered homeostasis in aging rod photoreceptors: implications for retinal diseases.
Age, Specimen partView Samples
We discuss the use of pluripotent stem cell lines carrying fluorescent reporters driven by retinal promoters to derive three-dimensional (3-D) retina in culture and how this system can be exploited for elucidating human retinal biology, creating disease models in a dish, and designing targeted drug screens for retinal and macular degeneration. Furthermore, we realize that stem cell investigations are labor-intensive and require extensive resources. To expedite scientific discovery by sharing of resources and to avoid duplication of efforts, we propose the formation of a Retinal Stem Cell Consortium. In the field of vision, such collaborative approaches have been enormously successful in elucidating genetic susceptibility associated with age-related macular degeneration. Overall design: CRX+ flow sorted cells from human retina derived organoids were collected at 6 time points during differentiation (day (D) 37, 48, 67, 90, 134, 220).
Treatment Paradigms for Retinal and Macular Diseases Using 3-D Retina Cultures Derived From Human Reporter Pluripotent Stem Cell Lines.
Specimen part, SubjectView Samples