A cationic tetrapyrrole inhibits toxic activities of the cellular prion protein

Prion diseases are rare neurodegenerative conditions associated with the conformational conversion of the cellular prion protein (PrPC) into PrPSc, a self-replicating isoform (prion) that accumulates in the central nervous system of affected individuals. The structure of PrPSc is poorly defined, and likely to be heterogeneous, as suggested by the existence of different prion strains. The latter represents a relevant problem for therapy in prion diseases, as some potent anti-prion compounds have shown strain-specificity. Designing therapeutics that target PrPC may provide an opportunity to overcome these problems. PrPC ligands may theoretically inhibit the replication of multiple prion strains, by acting on the common substrate of any prion replication reaction. Here, we characterized the properties of a cationic tetrapyrrole [Fe(III)-TMPyP], which was previously shown to bind PrPC, and inhibit the replication of a mouse prion strain. We report that the compound is active against multiple prion strains in vitro and in cells. Interestingly, we also find that Fe(III)-TMPyP inhibits several PrPC-related toxic activities, including the channel-forming ability of a PrP mutant, and the PrPC-dependent synaptotoxicity of amyloid-beta (A beta) oligomers, which are associated with Alzheimer's Disease. These results demonstrate that molecules binding to PrPC may produce a dual effect of blocking prion replication and inhibiting PrPC-mediated toxicity

Derangement of Ras-Guanine Nucleotide-Releasing Factor 1 (Ras-GRF1) and Extracellular Signal-Regulated Kinase (ERK) Dependent Striatal Plasticity in L-DOPA-Induced Dyskinesia

BACKGROUND: Bidirectional long-term plasticity at the corticostriatal synapse has been proposed as a central cellular mechanism governing dopamine-mediated behavioral adaptations in the basal ganglia system. Balanced activity of medium spiny neurons (MSNs) in the direct and the indirect pathways is essential for normal striatal function. This balance is disrupted in Parkinson's disease and in L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID), a common motor complication of current pharmacotherapy of Parkinson's disease. METHODS: Electrophysiological recordings were performed in mouse cortico-striatal slice preparation. Synaptic plasticity, such as long-term potentiation (LTP) and depotentiation, was investigated. Specific pharmacological inhibitors or genetic manipulations were used to modulate the Ras-extracellular signal-regulated kinase (Ras-ERK) pathway, a signal transduction cascade implicated in behavioral plasticity, and synaptic activity in different subpopulations of striatal neurons was measured. RESULTS: We found that the Ras-ERK pathway, is not only essential for long-term potentiation induced with a high frequency stimulation protocol (HFS-LTP) in the dorsal striatum, but also for its reversal, synaptic depotentiation. Ablation of Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1), a neuronal activator of Ras proteins, causes a specific loss of HFS-LTP in the medium spiny neurons in the direct pathway without affecting LTP in the indirect pathway. Analysis of LTP in animals with unilateral 6-hydroxydopamine lesions (6-OHDA) rendered dyskinetic with chronic L-DOPA treatment reveals a complex, Ras-GRF1 and pathway-independent, apparently stochastic involvement of ERK. CONCLUSIONS: These data not only demonstrate a central role for Ras-ERK signaling in striatal LTP, depotentiation, and LTP restored after L-DOPA treatment but also disclose multifaceted synaptic adaptations occurring in response to dopaminergic denervation and pulsatile administration of L-DOPA

Compartment-specific immunity in the human gut: Properties and functions of dendritic cells in the colon versus the ileum

© 2015 The Authors. Published by BMJ. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: http://dx.doi.org/10.1136/gutjnl-2014-307916Objective Dendritic cells (DC) mediate intestinal immune tolerance. Despite striking differences between the colon and the ileum both in function and bacterial load, few studies distinguish between properties of immune cells in these compartments. Furthermore, information of gut DC in humans is scarce. We aimed to characterise human colonic versus ileal DC. Design Human DC from paired colonic and ileal samples were characterised by flow cytometry, electron microscopy or used to stimulate T cell responses in a mixed leucocyte reaction. Results A lower proportion of colonic DC produced pro-inflammatory cytokines (tumour necrosis factor-a and interleukin (IL)-1ß) compared with their ileal counterparts and exhibited an enhanced ability to generate CD4+FoxP3+IL-10+ (regulatory) T cells. There were enhanced proportions of CD103+Sirpa- DC in the colon, with increased proportions of CD103+Sirpa+ DC in the ileum. A greater proportion of colonic DC subsets analysed expressed the lymph-node-homing marker CCR7, alongside enhanced endocytic capacity, which was most striking in CD103+Sirpa+ DC. Expression of the inhibitory receptor ILT3 was enhanced on colonic DC. Interestingly, endocytic capacity was associated with CD103+ DC, in particular CD103+Sirpa+ DC. However, expression of ILT3 was associated with CD103- DC. Colonic and ileal DC differentially expressed skin-homing marker CCR4 and small-bowel-homing marker CCR9, respectively, and this corresponded to their ability to imprint these homing markers on T cells. Conclusions The regulatory properties of colonic DC may represent an evolutionary adaptation to the greater bacterial load in the colon. The colon and the ileum should be regarded as separate entities, each comprising DC with distinct roles in mucosal immunity and imprinting.This research was funded by St. Mark's Foundation (Harrow, UK), The Biotechnology and Biological Sciences Research Council (BBSRC; BB/J004529/1) and The National Institutes of Health (NIH; US) including The National Institute of Diabetes and Digestive and Kidney Diseases (NIH/NIDDK; T32-DK07632 and P01-DK072084) and The National Institute of Allergy and Infectious Disease (NIH/NIAID; R21-AI094033). We also gratefully acknowledge funding support from The Harvey M. and Lyn P. Meyerhoff Inflammatory Bowel Disease Centre at The Johns Hopkins Hospital, Baltimore, US.Published versio

TGFβR signalling determines CD103⁺CD11b⁺ dendritic cell development in the intestine

CD103+CD11b+ dendritic cells (DCs) are unique to the intestine, but the factors governing their differentiation are unclear. Here we show that transforming growth factor receptor 1 (TGFβR1) has an indispensable, cell intrinsic role in the development of these cells. Deletion of Tgfbr1 results in markedly fewer intestinal CD103+CD11b+ DCs and a reciprocal increase in the CD103−CD11b+ dendritic cell subset. Transcriptional profiling identifies markers that define the CD103+CD11b+ DC lineage, including CD101, TREM1 and Siglec-F, and shows that the absence of CD103+CD11b+ DCs in CD11c-Cre.Tgfbr1fl/fl mice reflects defective differentiation from CD103−CD11b+ intermediaries, rather than an isolated loss of CD103 expression. The defect in CD103+CD11b+ DCs is accompanied by reduced generation of antigen-specific, inducible FoxP3+ regulatory T cells in vitro and in vivo, and by reduced numbers of endogenous Th17 cells in the intestinal mucosa. Thus, TGFβR1-mediated signalling may explain the tissue-specific development of these unique DCs

A re-investigation of the path of carbon in photosynthesis utilizing GC/MS methodology. Unequivocal verification of the participation of octulose phosphates in the pathway

A GC/EIMS/SIM methodology has been developed to re-examine the path of carbon in photosynthesis. Exposing isolated spinach chloroplasts to (13)CO(2 )on a solid support for a defined period followed by quenching and work-up provided a mixture of labelled sugar phosphates. After enzymatic dephosphorylation and derivatization, the Mox-TMS sugars were analysed using the above method. The purpose of the study was to try to calculate the atom% enrichment of (13)C in as many of the individual carbons in each of the derivatized sugars as was practical using diagnostic fragment ions. In the event, only one 45 s experiment provided sufficient data to enable a range of enrichment values to be calculated. This confirmed that D-glycero-D-altro-octulose phosphate was present in the chloroplasts and was heavily labelled in the C4, C5 and C6 positions, in keeping with the hypothesis that it had an inclusive role and a labelling pattern consistent with a new modified pathway of carbon in photosynthesis

Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns

[EN] Between February 2018 and April 2018, flowers were collected from eight Rosaceae species. Flowers were kept in a freezer at -20 degrees C for three freezing times (Treatment 1, two months; Treatment 2, four months; Treatment 3, six months). After extracting pollen, in vitro germination was induced in a culture medium and incubated at six different temperatures for 72 h. The percentage of pollen germination, average pollen tube length and maximum pollen tube length were measured. Pollen germination was maximum for all species between 15 degrees C and 30 degrees C. Cydonia oblonga, Malus sylvestris, Prunus avium, Prunus domestica, Prunus dulcis, Prunus persica and Pyrus communis obtained 30-52% pollen germination between 15 degrees C and 20 degrees C. Prunus cerasifera had 40% pollen germination at 30 degrees C. All species studied reached the maximum pollen tube length between 10 degrees C and 25 degrees C. Germination did not change significantly for any of the species with freezing time, but we found significant differences in the three parameters measured between treatments. The highest germination percentages were obtained in Treatment 2 (four months frozen at -20 degrees C), while the maximum pollen tube length was reached in Treatment 1 (two months frozen at -20 degrees C). According to our results, freezing time affected the germination-temperature patterns. This could indicate that studies on the effect of temperature on pollen germination should always be carried out with fresh pollen to obtain more conclusive data.This work was supported by the Asociacion Club de Variedades Vegetales Protegidas as a part of a project with the Universitat Politecnica de Valencia (UPV 20170673). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Beltrán, R.; Valls, A.; Cebrián, N.; Zornoza, C.; García-Breijo, F.; Reig Armiñana, J.; Garmendia, A.... (2019). Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns. PeerJ. 7:1-18. https://doi.org/10.7717/peerj.8195S1187Acar, I., & Kakani, V. G. (2010). The effects of temperature on in vitro pollen germination and pollen tube growth of Pistacia spp. Scientia Horticulturae, 125(4), 569-572. doi:10.1016/j.scienta.2010.04.040Boavida, L. C., & McCormick, S. (2007). TECHNICAL ADVANCE: Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana. The Plant Journal, 52(3), 570-582. doi:10.1111/j.1365-313x.2007.03248.xBrewbaker, J. L., & Kwack, B. H. (1963). 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Increased S-nitrosylation and proteasomal degradation of caspase-3 during infection contribute to the persistence of adherent invasive escherichia coli (AIEC) in immune cells

Adherent invasive Escherichia coli (AIEC) have been implicated as a causative agent of Crohn's disease (CD) due to their isolation from the intestines of CD sufferers and their ability to persist in macrophages inducing granulomas. The rapid intracellular multiplication of AIEC sets it apart from other enteric pathogens such as Salmonella Typhimurium which after limited replication induce programmed cell death (PCD). Understanding the response of infected cells to the increased AIEC bacterial load and associated metabolic stress may offer insights into AIEC pathogenesis and its association with CD. Here we show that AIEC persistence within macrophages and dendritic cells is facilitated by increased proteasomal degradation of caspase-3. In addition S-nitrosylation of pro- and active forms of caspase-3, which can inhibit the enzymes activity, is increased in AIEC infected macrophages. This S-nitrosylated caspase-3 was seen to accumulate upon inhibition of the proteasome indicating an additional role for S-nitrosylation in inducing caspase-3 degradation in a manner independent of ubiquitination. In addition to the autophagic genetic defects that are linked to CD, this delay in apoptosis mediated in AIEC infected cells through increased degradation of caspase-3, may be an essential factor in its prolonged persistence in CD patients

Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white vitis vinifera wine grapes

A non-destructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex ®) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g/kg fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a non-destructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture

To respond or not to respond - a personal perspective of intestinal tolerance

For many years, the intestine was one of the poor relations of the immunology world, being a realm inhabited mostly by specialists and those interested in unusual phenomena. However, this has changed dramatically in recent years with the realization of how important the microbiota is in shaping immune function throughout the body, and almost every major immunology institution now includes the intestine as an area of interest. One of the most important aspects of the intestinal immune system is how it discriminates carefully between harmless and harmful antigens, in particular, its ability to generate active tolerance to materials such as commensal bacteria and food proteins. This phenomenon has been recognized for more than 100 years, and it is essential for preventing inflammatory disease in the intestine, but its basis remains enigmatic. Here, I discuss the progress that has been made in understanding oral tolerance during my 40 years in the field and highlight the topics that will be the focus of future research

Corrigendum: CCR7-dependent trafficking of RORγ+ ILCs creates a unique microenvironment within mucosal draining lymph nodes

Presentation of peptide:MHCII by ​RORγ-expressing group 3 innate lymphoid cells (ILC3s), which are enriched within gut tissue, is required for control of ​CD4 T-cell responses to commensal bacteria. It is not known whether ILC populations migrate from their mucosal and peripheral sites to local draining secondary lymphoid tissues. Here we demonstrate that ILC3s reside within the interfollicular areas of mucosal draining lymph nodes, forming a distinct microenvironment not observed in peripheral lymph nodes. By photoconverting intestinal cells in Kaede mice we reveal constitutive trafficking of ILCs from the intestine to the draining mesenteric lymph nodes, which specifically for the LTi-like ILC3s was ​CCR7-dependent. Thus, ILC populations traffic to draining lymph nodes using different mechanisms