Project description:Patients with systemic lupus erythematosus (SLE) have a markedly increased risk to develop cardiovascular disease, and traditional cardiovascular risk factors fail to account for this increased risk. We used microarray to probe the platelet transcriptome in individuals with SLE and healthy controls, and the gene and protein expression of a subset of differentially expressed genes was further investigated and correlated to platelet activation status. Real-time PCR was used to confirm a type I interferon (IFN) gene signature in patients with SLE, and the IFN-regulated proteins PRKRA, IFITM1 and CD69 (p<0.0001) were found to be up-regulated in platelets from SLE patients as compared to healthy volunteers. Notably, patients with a history of vascular disease had increased expression of type I IFN-regulated proteins as well as more activated platelets as compared with patients without vascular disease. We suggest that interferogenic immune complexes stimulate production of IFNα which up-regulates the megakaryocytic type I IFN-regulated genes and proteins. This could affect platelet activation and contribute to development of vascular disease in SLE. In addition, platelets with type I IFN signature could be a novel marker for vascular disease in SLE.
Project description:Patients with systemic lupus erythematosus (SLE) have a markedly increased risk to develop cardiovascular disease, and traditional cardiovascular risk factors fail to account for this increased risk. We used microarray to probe the platelet transcriptome in individuals with SLE and healthy controls, and the gene and protein expression of a subset of differentially expressed genes was further investigated and correlated to platelet activation status. Real-time PCR was used to confirm a type I interferon (IFN) gene signature in patients with SLE, and the IFN-regulated proteins PRKRA, IFITM1 and CD69 (p<0.0001) were found to be up-regulated in platelets from SLE patients as compared to healthy volunteers. Notably, patients with a history of vascular disease had increased expression of type I IFN-regulated proteins as well as more activated platelets as compared with patients without vascular disease. We suggest that interferogenic immune complexes stimulate production of IFNα which up-regulates the megakaryocytic type I IFN-regulated genes and proteins. This could affect platelet activation and contribute to development of vascular disease in SLE. In addition, platelets with type I IFN signature could be a novel marker for vascular disease in SLE. Platelets were purified from SLE patients (n=10) and age and sex-matched healthy volunteers (n=10). cDNA was generated for each individual. For the microarray analysis, cDNA from the 10 SLE patients were pooled, as well as the cDNA from the 10 healthy volunteers to represent a mean mRNA expression level from 10 individuals.
Project description:Purpose: The aim of this study is to determine the relative expresson levels of mRNA transcripts in wild type platelets Methods: Total RNA was extracted and purified from purified platelets from BALB/c male mice (3 independent samples). Platelet purification was performed as described in Josefsson EC et al, Journal of Experimental Medicine (2011) 208:2017-31. Total RNA (100 ng) was used to generate sequencing libraries for whole transcriptome analysis following Illumina’s TruSeq RNA v2 sample preparation protocol. Completed libraries were sequenced on HiSeq 2000 with TruSeq SBS Kit v3- HS reagents (Illumina) as 100 bp paired-end reads at the Australian Genome Research Facility (AGRF), Melbourne. Reads were aligned to the mouse reference genome mm10 and counts for known genes were obtained using the Rsubread package (version 1.18.0) (Liao et al. 2013; Liao et al. 2014).
Project description:Purpose: Nxf1 is thought to be an essential nuclear exporter of messenger RNA (mRNA) in eukaryotic cells. Whether perturbations in the Nxf1 pathway affect mammalian physiology is not known. The aim of this study is to determine the impact of a Nxf1 mutation in the representation of mRNA transcripts in platelets. Methods: Platelets were purified from individual males. Blood was obtained by cardiac puncture into 0.1 volume of Aster Jandl citrate-based anticoagulant. Mouse platelet rich fraction was obtained by centrifugation of the murine blood at 125 g for 8 min at room temperature, followed by centrifugation of the supernatant buffy coat at 125 g for 8 min. Mouse platelets were washed by two sequential centrifugations at 860 g for 5 min in 140 mM NaCl, 5 mM KCl, 12 mM trisodium citrate, 10 mM glucose, and 12.5 mM sucrose, pH 6.0.The platelet pellet was resuspended in 10 mM Hepes, 140 Mm NaCl, 3 mM KCl, 0.5 mM MgCl2, 10 mM glucose, and 0.5 mM NaHCO3, pH 7.4. The purity of each platelet suspension was assessed by flow cytometry and suspensions for which more than 98% of total events were CD41+ platelets were pooled together. RNA was purified with Norgen cytoplasmic and nuclear fractionation RNA purification kit.
Project description:Despite abundant evidence demonstrating that platelets foster metastasis, anti- platelet agents have low therapeutic potential due to the risk of hemorrhages. In addition, whether platelets can regulate metastasis at the late stages of the disease remains unknown. In this study, we subjected syngeneic models of metastasis to various thrombocytopenic regimes to show that platelets provide a biphasic contribution to metastasis. While potent intravascular binding of platelets to tumor cells efficiently promotes metastasis, platelets further support the outgrowth of established metastases via immune suppression. Genetic depletion and pharmacological targeting of the platelet-specific receptor GPVI in humanized mouse models efficiently reduced the growth of established metastases, independently of active platelet binding to tumor cells in the bloodstream. Our study is the first to demonstrate therapeutic efficacy when targeting animals bearing growing metastases. It further identifies GPVI as the first molecular target whose inhibition can impair metastasis without inducing collateral hemostatic perturbations.
Project description:Platelets are blood cells who play critical roles in numerous biological and disease processes. This study was designed to identify lncRNAs that may play a role in platelet reactivity. In this study, by using large-scale deep sequencing, we determined the expression profiles of lncRNAs in both hyperreactive and hyporeactive human platelets. To determine the potential link between the expression of lncRNAs and the function of platelets, the expression profiles of hyperreactive and hyporeactive platelets were compared. Compared with hyperreactive platelets, deep sequencing analysis demonstrated that differential lncRNA expression was a remarkable characteristic in hyporeactive platelets.
Project description:Early diagnosis of acute myeloid leukemia (AML) in the pre-leukemic stage remains a clinical challenge, as pre-leukemic patients show no symptoms, lacking any known morphological or numerical abnormalities in blood cells. Here, we demonstrate that platelets with structurally abnormal mitochondria emerge at the pre-leukemic phase of AML, preceding detectable changes in blood cell counts or detection of leukemic blasts in blood. We visualized frozen-hydrated platelets from mice at different time points during AML development in situ using electron cryo-tomography (cryo-ET) and identified intracellular organelles through an unbiased semi-automatic process followed by quantitative measurement. A large proportion of platelets exhibited changes in the overall shape and depletion of organelles in AML. Notably, 23% of platelets in pre-leukemic cells exhibit abnormal, round mitochondria with unfolded cristae, accompanied by a significant drop in ATP levels and altered expression of metabolism-related gene signatures. Our study demonstrates that detectable structural changes in pre-leukemic platelets may serve as a biomarker for the early diagnosis of AML.
Project description:Platelets are small anucleate cells derived from the fragmentation of megakaryocytes and are involved in different biological processes especially hemostasis, thrombosis and immune response. Platelet purification is a crucial step in transcriptomic analysis, and researchers usually encounter the problem of platelet contamination by leukocytes and erythrocytes. Leukocytes contain much more RNA than platelets, thus the presence of few contaminants in platelet preparation can strongly alter transcriptome results. Using microarray technique, we compared transcriptome of platelets from the same donor, purified by common centrifugation method or using magnetic microbeads to eliminate contaminating cells.
Project description:Human blood platelets have important, regulatory functions in diverse hemostatic and pathological disorders, including vascular remodeling, inflammation, and wound repair. Microarray analysis was used to study the molecular basis of essential thrombocythemia, a myeloproliferative disorder with quantitative and qualitative platelet defects associated with cardiovascular and thrombohemorrhagic symptoms, not infrequently neurological. A platelet-expressed gene (HSD17B3) encoding type 3 17beta-hydroxysteroid dehydrogenase (previously characterized as a testis-specific enzyme catalyzing the final step in gonadal synthesis of testosterone) was selectively down-regulated in ET platelets, with reciprocal induction of the type 12 enzyme (HSD17B12). Functional 17beta-HSD3 activity corresponding to approximately 10% of that found in murine testis was demonstrated in normal platelets. The induction of HSD17B12 in ET platelets was unassociated with a concomitant increase in androgen biosynthesis, suggesting distinct functions and/or substrate specificities of the types 3 and 12 enzymes. Application of a molecular assay distinguished ET from normal platelets in 20 consecutive patients (p < 0.0001). These data provide the first evidence that distinct subtypes of steroidogenic 17beta-HSDs are functionally present in human blood platelets, and that the expression patterns of HSD17B3 and HSD17B12 are associated with an uncommon platelet disorder manifest by quantitative and qualitative platelet defects. Keywords: other
Project description:Human blood platelets have important, regulatory functions in diverse hemostatic and pathological disorders, including vascular remodeling, inflammation, and wound repair. Microarray analysis was used to study the molecular basis of essential thrombocythemia, a myeloproliferative disorder with quantitative and qualitative platelet defects associated with cardiovascular and thrombohemorrhagic symptoms, not infrequently neurological. A platelet-expressed gene (HSD17B3) encoding type 3 17beta-hydroxysteroid dehydrogenase (previously characterized as a testis-specific enzyme catalyzing the final step in gonadal synthesis of testosterone) was selectively down-regulated in ET platelets, with reciprocal induction of the type 12 enzyme (HSD17B12). Functional 17beta-HSD3 activity corresponding to approximately 10% of that found in murine testis was demonstrated in normal platelets. The induction of HSD17B12 in ET platelets was unassociated with a concomitant increase in androgen biosynthesis, suggesting distinct functions and/or substrate specificities of the types 3 and 12 enzymes. Application of a molecular assay distinguished ET from normal platelets in 20 consecutive patients (p < 0.0001). These data provide the first evidence that distinct subtypes of steroidogenic 17beta-HSDs are functionally present in human blood platelets, and that the expression patterns of HSD17B3 and HSD17B12 are associated with an uncommon platelet disorder manifest by quantitative and qualitative platelet defects.