Project description:<p>CHD is the leading cause of death in the United States. One of the most common ways to prevent CHD is to take an anti-platelet agent, which lessens platelet aggregation. Two of the most common anti-platelet agents are aspirin and clopidogrel. However, up to 25% to 30% of people do not respond to these medications. Evidence indicates that treatment response may be related to genetics. The purpose of this study is to determine specific gene variants that predict response to aspirin and clopidogrel therapy.</p> <p>This study is part of a larger group of studies called the Pharmacogenomics Research Network (PGRN). Participants are from the Old Order Amish of Lancaster, Pennsylvania. They are well suited for genetic studies because they are a homogenous, closed, founder population. Participants received 300 mg of clopidogrel on the first day, then 75 mg of clopidogrel per day for the next 6 days. On the last day of clopidogrel treatment, participants took a single dose of 324 mg aspirin. Participants underwent platelet function tests before and after clopidogrel alone, and then again after taking clopidogrel plus aspirin. Using the gene variation profiles across the genome, researchers analyzed which variants correspond to treatment response.</p>
Project description:<p>CHD is the leading cause of death in the United States. One of the most common ways to prevent CHD is to take an anti-platelet agent, which lessens platelet aggregation. Two of the most common anti-platelet agents are aspirin and clopidogrel. However, up to 25% to 30% of people do not respond to these medications. Evidence indicates that treatment response may be related to genetics. The purpose of this study is to determine specific gene variants that predict response to aspirin and clopidogrel therapy.</p> <p>This study is part of a larger group of studies called the Pharmacogenomics Research Network (PGRN). Participants are from the Old Order Amish of Lancaster, Pennsylvania. They are well suited for genetic studies because they are a homogenous, closed, founder population. Participants received 300 mg of clopidogrel on the first day, then 75 mg of clopidogrel per day for the next 6 days. On the last day of clopidogrel treatment, participants took a single dose of 324 mg aspirin. Participants underwent platelet function tests before and after clopidogrel alone, and then again after taking clopidogrel plus aspirin. Using the gene variation profiles across the genome, researchers analyzed which variants correspond to treatment response.</p>
Project description:Bombyx Papi contains two K-homology (KH) domains and one Tudor domain, and acts as a scaffold for Siwi-piRISC biogenesis on the mitochondrial surface. To initiate this process, Papi binds first to Siwi via the Tudor domain and subsequently to piRNA precursors loaded onto Siwi via the KH domains. This second action depends on phosphorylation of Papi. However, its underlying mechanism remains unknown. Here, we show that Siwi targets Par-1 kinase to mitochondrial Papi to promote its phosphorylation at Ser547 in the auxiliary domain and that this modification enhances the ability of Papi to bind Siwi-bound piRNA precursors via the KH domains. Papi S547A mutant still bound to Siwi, like wild-type (WT) Papi, although it evaded phosphorylation by Par-1: Consequently, Papi lost the ability to bind RNAs, abrogating the generation of Siwi-piRISC. Papi mutant lacking the Tudor and auxiliary domains escaped coordinated regulation by Siwi and Par-1 and lost their bias to bind piRNA precursors. Pseudo-phosphorylation mutants of Papi restored Siwi-piRISC formation in Papi-lacking cells, but their ability to bind RNAs required Siwi, similar to WT Papi. Par-1-dependent, multilayered mechanism by which Siwi regulates the role of Papi in Siwi-piRISC biogenesis was revealed.
Project description:Clopidogrel and aspirin are commonly prescribed anti-platelet medications indicated for patients who have experienced, or are at risk for, ischemic cardiovascular events. The Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study was designed to characterize determinants of clopidogrel and dual anti-platelet therapy (DAPT) response in a healthy cohort of Old Order Amish from Lancaster, PA. Following a loading dose, clopidogrel was taken once a day for 7 days. One hour after the last dose of clopidogrel, 325 mg of aspirin was given. Ex vivo platelet aggregometry was performed at baseline, post-clopidogrel, and post-DAPT. Platelet aggregation measurements were significantly lower after both interventions for all agonists tested (p <0.05), although there was large inter-individual variation in the magnitude of anti-platelet response. Female sex and older age were associated with higher platelet aggregation at all three time-points. Change in aggregation was correlated among the various agonists at each time point. Heritability (h2) of change in platelet aggregation was significant for most traits at all time-points (range h2=0.14-0.57). Utilization of a standardized, short-term intervention provided a powerful approach to investigate sources of variation in platelet aggregation response due to drug therapy. Further, this short-term intervention approach may provide a useful paradigm for pharmacogenomics studies.
Project description:PIWI-interacting RNAs (piRNAs) are germline-enriched small RNAs that control transposons to maintain genome integrity1,2,3. To achieve this, piRNAs bind PIWI proteins upon being processed from piRNA precursors1,2,3. Bioinformatic studies of piRNA biogenesis in Drosophila showed that the piRNA 5′ end is formed by PIWI-Slicer or Zucchini (Zuc) endonucleolytic cleavage, while the 3′ end is formed by Zuc or Nibbler (Nbr) 3′-to-5′ exonucleolytic activity4,5,6. piRNA 3′-end formation in Bombyx was shown to be mediated by PNLDC1/Trimmer (Trim) 3′-to-5′ exonuclease7, while piRNA intermediates are bound with PIWI anchored onto mitochondrial protein PAPI8. However, the requirement for Zuc and Nbr in piRNA biogenesis in Bombyx has not been elucidated. Here, we applied biochemical approaches to understand their involvement in piRNA biogenesis and revealed that Zuc endonuclease, but not Trim and Nbr exonucleases, plays a crucial role in Bombyx piRNA 3′-end formation. Loss of Zuc had little effect on the levels of Trim and Nbr, but led to the aberrant accumulation of piRNA intermediates within the PAPI complex, which were processed to mature piRNAs by recombinant Zuc. Zuc copurified with PAPI, and PAPI exerted RNA-binding activity only when Siwi coexisted with it and PAPI was phosphorylated, suggesting that complex assembly proceeds via a hierarchical process. Bioinformatic analyses of piRNA intermediates within the PAPI complex revealed that both the 5′ and the 3′ ends showed the hallmark of PIWI-Slicer, yet no phasing pattern was observed in mature piRNAs. These findings strongly support the notion that, in Bombyx piRNA, the 5′ end is formed by PIWI-Slicer, but independently of Zuc, while the 3′ end is formed by Zuc endonuclease. The Bombyx piRNA biogenesis is simpler than that of Drosophila, which is reasonable considering that Bombyx has no transcriptional silencing machinery relying on phased piRNAs.
Project description:MicroRNAs (miRNAs) regulate cell physiology by altering protein expression, but the biology of platelet miRNAs is largely unexplored. We tested whether platelet miRNA levels were associated with platelet reactivity by genome-wide profiling using platelet RNA from 19 healthy subjects. We found that human platelets express 284 miRNAs. Unsupervised hierarchical clustering of miRNA profiles resulted in 2 groups of subjects that appeared to cluster by platelet aggregation phenotypes. Seventy-four miRNAs were differentially expressed (DE) between subjects grouped according to platelet aggregation to epinephrine, a subset of which predicted the platelet reactivity response. Using whole genome mRNA expression data on these same subjects, we computationally generated a high-priority list of miRNA-mRNA pairs in which the DE platelet miRNAs had binding sites in 3'UTRs of DE mRNAs, and the levels were negatively correlated. Three miRNA-mRNA pairs (miR-200b:PRKAR2B, miR-495:KLHL5 and miR-107:CLOCK) were selected from this list and all 3 miRNAs knocked down protein expression from the target mRNA. Reduced activation from platelets lacking PRKAR2B supported these findings. In summary, (1) platelet miRNAs are able to repress expression of platelet proteins, (2) miRNA profiles are associated with and may predict platelet reactivity, and (3) bioinformatic approaches can successfully identify functional miRNAs in platelets. Total RNA from the platelets of 19 donors was harvested and labeled with Hy3. Reference RNA (a pool of all samples) was labeled with Hy5. This submission represents the miRNA expression component of the study.
Project description:MicroRNAs (miRNAs) regulate cell physiology by altering protein expression, but the biology of platelet miRNAs is largely unexplored. We tested whether platelet miRNA levels were associated with platelet reactivity by genome-wide profiling using platelet RNA from 19 healthy subjects. We found that human platelets express 284 miRNAs. Unsupervised hierarchical clustering of miRNA profiles resulted in 2 groups of subjects that appeared to cluster by platelet aggregation phenotypes. Seventy-four miRNAs were differentially expressed (DE) between subjects grouped according to platelet aggregation to epinephrine, a subset of which predicted the platelet reactivity response. Using whole genome mRNA expression data on these same subjects, we computationally generated a high-priority list of miRNA-mRNA pairs in which the DE platelet miRNAs had binding sites in 3'UTRs of DE mRNAs, and the levels were negatively correlated. Three miRNA-mRNA pairs (miR-200b:PRKAR2B, miR-495:KLHL5 and miR-107:CLOCK) were selected from this list and all 3 miRNAs knocked down protein expression from the target mRNA. Reduced activation from platelets lacking PRKAR2B supported these findings. In summary, (1) platelet miRNAs are able to repress expression of platelet proteins, (2) miRNA profiles are associated with and may predict platelet reactivity, and (3) bioinformatic approaches can successfully identify functional miRNAs in platelets.