The repertoire and features of human platelet microRNAs

Playing a central role in the maintenance of hemostasis as well as in thrombotic disorders, platelets contain a relatively diverse messenger RNA (mRNA) transcriptome as well as functional mRNA-regulatory microRNAs, suggesting that platelet mRNAs may be regulated by microRNAs. Here, we elucidated the complete repertoire and features of human platelet microRNAs by high-throughput sequencing. More than 492 different mature microRNAs were detected in human platelets, whereas the list of known human microRNAs was expanded further by the discovery of 40 novel microRNA sequences. As in nucleated cells, platelet microRNAs bear signs of post-transcriptional modifications, mainly terminal adenylation and uridylation. In vitro enzymatic assays demonstrated the ability of human platelets to uridylate microRNAs, which correlated with the presence of the uridyltransferase enzyme TUT4. We also detected numerous microRNA isoforms (isomiRs) resulting from imprecise Drosha and/or Dicer processing, in some cases more frequently than the reference microRNA sequence, including 5′ shifted isomiRs with redirected mRNA targeting abilities. This study unveils the existence of a relatively diverse and complex microRNA repertoire in human platelets, and represents a mandatory step towards elucidating the intraplatelet and extraplatelet role, function and importance of platelet microRNAs

How value co-creation and co-destruction unfolds: a longitudinal perspective on dialogic engagement in health services interactions

Complex services, such as healthcare, struggle to realize the benefits of value co-creation due to the substantial challenges of managing such services over the long-term. Key to overcoming these challenges to value co-creation is a profound understanding of dialogue (i.e., ‘quality of discourse’ facilitating shared meaning) during service interactions. Contributing to an emerging literature, we undertake a longitudinal, ethnographic study to assess dialogue between professionals and patients through the lens of dialogic engagement (i.e., iterative mutual learning processes that bring about action through dialogue). We develop and empirically support six dialogic co-creation and co-destruction mechanisms that impact on the resolution of tensions and integration of knowledge resources between service providers and consumers. We reveal the multidimensional and dynamic nature of value created or destroyed through these mechanisms in dialogue over time. Taking healthcare as an exemplar, we offer a research agenda for developing our understanding of DE in complex services

Racial differences in human platelet PAR4 reactivity reflect expression of PCTP and miR-376c.

Racial differences in the pathophysiology of atherothrombosis are poorly understood. We explored the function and transcriptome of platelets in healthy black (n = 70) and white (n = 84) subjects. Platelet aggregation and calcium mobilization induced by the PAR4 thrombin receptor were significantly greater in black subjects. Numerous differentially expressed RNAs were associated with both race and PAR4 reactivity, including PCTP (encoding phosphatidylcholine transfer protein), and platelets from black subjects expressed higher levels of PC-TP protein. PC-TP inhibition or depletion blocked PAR4- but not PAR1-mediated activation of platelets and megakaryocytic cell lines. miR-376c levels were differentially expressed by race and PAR4 reactivity and were inversely correlated with PCTP mRNA levels, PC-TP protein levels and PAR4 reactivity. miR-376c regulated the expression of PC-TP in human megakaryocytes. A disproportionately high number of microRNAs that were differentially expressed by race and PAR4 reactivity, including miR-376c, are encoded in the DLK1-DIO3 locus and were expressed at lower levels in platelets from black subjects. These results suggest that PC-TP contributes to the racial difference in PAR4-mediated platelet activation, indicate a genomic contribution to platelet function that differs by race and emphasize a need to consider the effects of race when developing anti-thrombotic drugs

Uridylation and adenylation of RNAs

The posttranscriptional addition of nontemplated nucleotides to the 3′ ends of RNA molecules can have a significant impact on their stability and biological function. It has been recently discovered that nontemplated addition of uridine or adenosine to the 3′ ends of RNAs occurs in different organisms ranging from algae to humans, and on different kinds of RNAs, such as histone mRNAs, mRNA fragments, U6 snRNA, mature small RNAs and their precursors etc. These modifications may lead to different outcomes, such as increasing RNA decay, promoting or inhibiting RNA processing, or changing RNA activity. Growing pieces of evidence have revealed that such modifications can be RNA sequence-specific and subjected to temporal or spatial regulation in development. RNA tailing and its outcomes have been associated with human diseases such as cancer. Here, we review recent developments in RNA uridylation and adenylation and discuss the future prospects in this research area

A Numerical study of compacted clay tensile strength by discrete element modelling: A bending test application

International audienceThe study of the clay tensile behaviour is one of the topics which requires a specific lighting especially when we give a closely attention to the pathology of the constructions built with or on the clays submitted to significant tensilestrenght. Therefore, failure or damage of clay can be related especially to tensile limit and not to shear limit overtaking. It is the case of compacted clay liners in wastes landfill cover or for embankments built on high compressible soils. In order to study the tensile compacted clay behaviour, a series of laboratory bending tests were carried out. On the basis of the test results, different numerical simulations using Discrete Element Method were engaged. Two numerical bending tests were carried out: a three points bending and a four points bending. A comparison between the two numerical protocols is given. Four analytical models (classical elasticity, bimodular elasticity, differential model and struts-tie method) are used in order to interpret bending tests results and are compared with the numerical simulations. At the same time, the validity of the assumptions relative to the four models was discussed. To outcome to these results, a study and an adjustment of numerical and micromechanical parameters were carried out. It was demonstrated that the Discrete Element Method has a strong correlation with laboratory tests and can contribute somewhat to the understanding and discussion on the validity degree of the kind of indirect tests and of their interpretation

Novel mature microRNA sequences detected in human platelets.

<p>Novel mature microRNA sequences detected in human platelets.</p

The small RNA profile of human platelets.

<p>(A) Size distribution of usable reads detected in each of the platelet RNA pool 1 and 2. Most of the RNA sequences are 21 to 23 nucleotides (nt) in length, representing 88% and 83% of the sequences obtained from pool 1 and pool 2, respectively. (B) Classification of the small RNA species isolated and sequenced from human platelet RNA pool 1 and 2. The proportion of sequences (%) matching to each RNA category is shown. MicroRNAs represent approximately 80% of the small RNA species between 18 and 30 nt in length in human platelets.</p

Detection of multiple microRNA isoforms in human platelets.

<p>The expression level of the main isoforms of miR-140-3p are shown. The expected mature microRNA sequence, as retrieved from miRBase, is highlighted in bold and does not correspond to the most frequently encountered isoform. As shown on the left, most of the miR-140-3p isoforms may result from a combination of imprecise processing by Drosha and/or Dicer, including the most abundant, whose cleavage sites on the pre-microRNA species are shifted towards the 3′ end by a single nucleotide. Of notice 2 major miR-140-3p isomiRs population coexist in platelets depending on 5′clivage by Dicer, either at the canonical position (blue bars) or harboring a 1 nt cleavage shift (red bars).</p