The glycoprotein VI (GPVI)-Fc receptor γ (FcRγ) chain is the major platelet signaling receptor for collagen. Paradoxically, in a FeCl3 injury model, occlusion, but not initiation of thrombus formation, is delayed in GPVI-deficient and GPVI-depleted mice. In this study, we demonstrate that GPVI is a receptor for fibrin and speculate that this contributes to development of an occlusive thrombus. We observed a marked increase in tyrosine phosphorylation, including the FcRγ chain and Syk, in human and mouse platelets induced by thrombin in the presence of fibrinogen and the αIIbβ3 blocker eptifibatide. This was not seen in platelets stimulated by a protease activated receptor (PAR)-4 peptide, which is unable to generate fibrin from fibrinogen. The pattern of tyrosine phosphorylation was similar to that induced by activation of GPVI. Consistent with this, thrombin did not induce tyrosine phosphorylation of Syk and the FcRγ chain in GPVI-deficient mouse platelets. Mouse platelets underwent full spreading on fibrin but not fibrinogen, which was blocked in the presence of a Src kinase inhibitor or in the absence of GPVI. Spreading on fibrin was associated with phosphatidylserine exposure (procoagulant activity), and this too was blocked in GPVI-deficient platelets. The ectodomain of GPVI was shown to bind to immobilized monomeric and polymerized fibrin. A marked increase in embolization was seen following FeCl3 injury in GPVI-deficient mice, likely contributing to the delay in occlusion in this model. These results demonstrate that GPVI is a receptor for fibrin and provide evidence that this interaction contributes to thrombus growth and stability.
Key Points CLEC-2 activation induces proteolytic cleavage of GPVI and FcγRIIa but not itself. CLEC-2 but not GPVI is detected on platelet-derived microparticles.
Background: Fucoidan was tested as a novel drug for hemophilia, but its effect on platelets has not been studied. Results: We show that fucoidan activates human and mouse platelets and that activation is blocked in CLEC-2 knock-out murine platelets. Conclusion: Fucoidan is a novel agonist for the CLEC-2. Significance: Understanding the effects of fucoidan on platelets can help in designing efficient drugs for hemophilia.
Platelets are activated by a range of stimuli that share little or no resemblance in structure to each other or to recognized ligands, including diesel exhaust particles (DEP), small peptides [4N1-1, Champs (computed helical anti-membrane proteins), LSARLAF (Leu-Ser-Ala-Arg-Leu-Ala-Phe)], proteins (histones) and large polysaccharides (fucoidan, dextran sulfate). This miscellaneous group stimulate aggregation of human and mouse platelets through the glycoprotein VI (GPVI)-FcR γ-chain complex and/or C-type lectin-like receptor-2 (CLEC-2) as shown using platelets from mice deficient in either or both of these receptors. In addition, all of these ligands stimulate tyrosine phosphorylation in GPVI/CLEC-2-double-deficient platelets, indicating that they bind to additional surface receptors, although only in the case of dextran sulfate does this lead to activation. DEP, fucoidan and dextran sulfate, but not the other agonists, activate GPVI and CLEC-2 in transfected cell lines as shown using a sensitive reporter assay confirming a direct interaction with the two receptors. We conclude that this miscellaneous group of ligands bind to multiple proteins on the cell surface including GPVI and/or CLEC-2, inducing activation. These results have pathophysiological significance in a variety of conditions that involve exposure to activating charged/hydrophobic agents.
BackgroundType 2 diabetes mellitus (T2DM) is a multifactorial disorder that leads to alterations in gene regulation. Long non-coding RNAs (lncRNAs) have become a major research topic as they are involved in metabolic disorders.MethodsThis study included a total of 400 study subjects; 200 were subjects with T2DM and 200 were healthy subjects. Extracted RNA was used to synthesize cDNA by quantitative real time. Serum analysis was carried out to determine differences in biochemical parameters. Recorded data were used to evaluate associations with expression of lncRNAs NF-kappaB interacting lncRNA (NKILA), nuclear enriched abundant transcript 1 (NEAT1), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and myocardial infarction-associated transcript (MIAT) in T2DM cases.ResultsCompared with healthy controls, patients with T2DM showed an overall increase in expression of lncRNAs NKILA, NEAT, MALAT1, and MIAT by 3.94-fold, 5.28-fold, 4.46-fold, and 6.35-fold, respectively. Among patients with T2DM, higher expression of lncRNA NKILA was associated with hypertension (p=0.001), smoking (p<0.0001), and alcoholism (p<0.0001). Altered NEAT1 expression was significantly associated with weight loss (p=0.04), fatigue (p=0.01), slow wound healing (p=0.002), blurred vision (p=0.008), loss of appetite (p=0.007), smoking (p<0.0001), and alcoholism (p<0.0001). Higher expression of lncRNA MALAT1 was significantly linked with weight loss (p=0.003), blurred vision (p=0.01), smoking (p<0.0001), and alcoholism (p<0.0001). Expression of lncRNA MIAT was associated with only blurred vision (p<0.0001), smoking (p<0.0001), and alcoholism (p<0.0001). Positive correlations of lncRNA NKILA with lncRNAs NEAT1 (r=0.42, p<0.0001), MALAT (r=0.36, p<0.0001) and MIAT (r=0.42, p<0.0001) were observed among patients with T2DM. Significant positive correlations of lncRNA NEAT with lncRNAs MALAT and MIAT were observed among patients with T2DM. A positive correlation between lncRNAs MALAT and MIAT was also observed among patients with T2DM.ConclusionIncreased circulating NKILA, NEAT1, MALAT, and MIAT expression in patients with T2DM, which is linked with poor patient outcomes and significantly linked with alcoholism and smoking, may influence the degree and severity of disease among patients with T2DM. These lncRNAs may contribute to the progression of T2DM disease or other related diabetes-related complications.
The knowledge of Red blood cells polymorphism and blood group antigens prevalence at the local and regional levels is necessary for safe blood transfusion services. This study was aimed to estimate the prevalence of significant blood group phenotypes like ABO, Rh, and Kell among the Najran people of Saudi Arabia. The transfusion transmittable infection (TTI) rate and blood abnormalities among various blood types were assessed to ensure safe blood transfusion. ABO and Rh blood prevalence (n=970) and Rh phenotype polymorphism were estimated in over 531 unrelated donors. The blood samples were screened for certain TTIs like AHBC- Anti-hepatitis B core, HTLV-1- human T-lymphotropic virus type I, HCV- hepatitis C virus, HBsAg- Hepatitis B antigen, HIV- Human immunodeficiency virus, SIC- Sickle cell, MP- Malaria parasite, and SYP- Syphilis. The selected samples were also observed for blood abnormalities by performing a complete blood count (CBC). Out of 970 subjects, 966 were males, and only 4 were females. The O>A>B>AB blood groups were identified with 46.89, 29.3, 9.1, and 2.38% prevalence among Rh-positive phenotype. While in the Rh system, 87.6% and 12.3% of Rh positive and Rh negative was observed. Among 953 samples, the prevalence of seropositive donors was approximately 5.66%. The screening showed about 5.036, 0.104, 0.314, 0.209, 2.18, 0.104, and 0.209% positivity for AHBC, HCV, HBsAg, HIV, SIC, MP, and SYP respectively. Results found that the frequency of D, C, E, c, and e were 99.9%, 67.98, 25.8, 77.9, 98.49%, respectively, in over 531 subjects. The e allele was more prevalent in Najran city. After observing the variations in the CBC parameters among the donors, it was perceived that about 28.78, 99.9, 29.41, and 31.6% of blood abnormalities were noticed for O, AB, B, and A blood groups, respectively. For blood banks and transfusion services, which play a significant role in the medical care of the patient, awareness of the distribution of the blood group is essential. Increasing consistency of blood donation programs would improve both donor satisfaction and motivation for potential donations of blood in near future.
Based on the diverse pharmacological potency and the structural features of succinimide, this research considered to synthesize succinimide derivatives. Moreover, these compounds were estimated for their biological potential in terms of anti-diabetic, anti-cholinesterase, and anti-oxidant capacities. The compounds were synthesized through Michael addition of various ketones to N-aryl maleimides. Similarly, the MOE software was used for the molecular docking study to explore the binding mode of the potent compounds against different enzymes. In the anti-cholinesterase activity, the compounds MSJ2 and MSJ10 exhibited outstanding activity against acetylcholinesterase (AChE), i.e., 91.90, 93.20%, and against butyrylcholinesterase (BChE), i.e., 97.30, 91.36% inhibitory potentials, respectively. The compounds MSJ9 and MSJ10 exhibited prominent α-glucosidase inhibitory potentials, i.e., 87.63 and 89.37 with IC50 value of 32 and 28.04 μM, respectively. Moreover, the compounds MSJ2 and MSJ10 revealed significant scavenging activity against DPPH free radicals with IC50 values of 2.59 and 2.52, while against ABTS displayed excellent scavenging potential with IC50 values 7.32 and 3.29 μM, respectively. The tentative results are added with molecular docking studies in the active sites of enzymes to predict the theoretical protein-ligand binding modes. Further detailed mechanism-based studies in animal models are essential for the in vivo evaluation of the potent compound.
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