Integrins and other adhesion receptors are essential components for outside-in and inside-out signaling through the cell membrane. The platelet glycoprotein IIb-IIIa (also known as fibrinogen receptor or integrin q&) is activated by platelet agonists, inhibited by cyclic-nucleotide-elevating agents, and is involved in the activation of protein tyrosine kinases including the 125-kDa focal adhesion kinase (~~1 2 5~~~) .However, the molecular details of glycoprotein IIb-IIIa regulation are not well understood. Here we report that in ADP-activated human platelets CAMP-and cGMPdependent protein-kinase-mediated phosphorylation of the focal adhesion vasodilator-stimulated phosphoprotein (VASP) at Ser157 correlates well with glycoprotein IIb-IIIa inhibition. Human platelets contain similar concentrations of glycoprotein IIb-IIIa complexes (fibrinogen binding sites) and VASP. Using gel-filtered platelets, CAMP-elevating agents [e.g. prostaglandin E, and the forskolin analog 6-(3-dimethylaminopropionyl)forskolin (NKH 477)] caused VASP Ser157 phosphorylation and inhibited glycoprotein IIb-IIIa activation up to 70-100%. NO-generating, cGMP-elevating agents [e.g. 3-morpholinosydnonimine hydrochloride (SIN1) and sodium nitroprusside] stimulated VASP Ser157 phosphorylation and inhibited glycoprotein IIb-IIIa activation up to a maximal extent of 30-50%. The effects of CAMP-and cGMP-elevating agents on VASP phosphorylation and fibrinogen binding were reversible and could be mimicked by membrane-permeant selective activators of platelet CAMP-or cGMP-dependent protein kinase, respectively. Using threshold concentrations, the nitrovasodilator SIN 1 potentiated the effects of the forskolin analog NKH 477 with respect to inhibition of platelet aggregation, VASP phosphorylation and glycoprotein IIb-IIIa inhibition. It is proposed that the inhitition of glycoprotein IIb-IIIa induced by cyclic nucleotide involves CAMPand cGMP-dependent protein-kinase-mediated VASP phosphorylation at Ser157.Adhesion, activation and aggregation of platelets and platelet -vessel-wall interactions are tightly regulated under physiological conditions and often impaired in diseases including congenital hemorrhagic diseases, atherosclerosis, hypertension and diabetes 11, 21. Important components of this vascular cell -cell and cell -matrix interaction are integrins and other adhesion receptors [3 -81. The platelet glycoprotein IIb-IIIa ((xllbp3) is one of the best-studied integrins and represents the functional fibrinogen receptor which is absent or impaired in the hereditary disorder Glanzmann's thrombasthenia [l, 5-81. Activated platelets contain at their sur-
Aims/hypothesisThe DIRECT (Diabetes Research on Patient Stratification) Study is part of a European Union Framework 7 Innovative Medicines Initiative project, a joint undertaking between four industry and 21 academic partners throughout Europe. The Consortium aims to discover and validate biomarkers that: (1) predict the rate of glycaemic deterioration before and after type 2 diabetes onset; (2) predict the response to diabetes therapies; and (3) help stratify type 2 diabetes into clearly definable disease subclasses that can be treated more effectively than without stratification. This paper describes two new prospective cohort studies conducted as part of DIRECT.MethodsPrediabetic participants (target sample size 2,200–2,700) and patients with newly diagnosed type 2 diabetes (target sample size ~1,000) are undergoing detailed metabolic phenotyping at baseline and 18 months and 36 months later. Abdominal, pancreatic and liver fat is assessed using MRI. Insulin secretion and action are assessed using frequently sampled OGTTs in non-diabetic participants, and frequently sampled mixed-meal tolerance tests in patients with type 2 diabetes. Biosamples include venous blood, faeces, urine and nail clippings, which, among other biochemical analyses, will be characterised at genetic, transcriptomic, metabolomic, proteomic and metagenomic levels. Lifestyle is assessed using high-resolution triaxial accelerometry, 24 h diet record, and food habit questionnaires.Conclusions/interpretationDIRECT will yield an unprecedented array of biomaterials and data. This resource, available through managed access to scientists within and outside the Consortium, will facilitate the development of new treatments and therapeutic strategies for the prevention and management of type 2 diabetes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-014-3216-x) contains peer-reviewed but unedited supplementary material, which is available to authorised users.
Aims/hypothesis Here, we describe the characteristics of the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) epidemiological cohorts at baseline and follow-up examinations (18, 36 and 48 months of follow-up). Methods From a sampling frame of 24,682 adults of European ancestry enrolled in population-based cohorts across Europe, participants at varying risk of glycaemic deterioration were identified using a risk prediction algorithm (based on age, BMI, waist circumference, use of antihypertensive medication, smoking status and parental history of type 2 diabetes) and enrolled into a prospective cohort study ( n = 2127) (cohort 1, prediabetes risk). We also recruited people from clinical registries with type 2 diabetes diagnosed 6–24 months previously ( n = 789) into a second cohort study (cohort 2, diabetes). Follow-up examinations took place at ~18 months (both cohorts) and at ~48 months (cohort 1) or ~36 months (cohort 2) after baseline examinations. The cohorts were studied in parallel using matched protocols across seven clinical centres in northern Europe. Results Using ADA 2011 glycaemic categories, 33% ( n = 693) of cohort 1 (prediabetes risk) had normal glucose regulation and 67% ( n = 1419) had impaired glucose regulation. Seventy-six per cent of participants in cohort 1 was male. Cohort 1 participants had the following characteristics (mean ± SD) at baseline: age 62 (6.2) years; BMI 27.9 (4.0) kg/m 2 ; fasting glucose 5.7 (0.6) mmol/l; 2 h glucose 5.9 (1.6) mmol/l. At the final follow-up examination the participants’ clinical characteristics were as follows: fasting glucose 6.0 (0.6) mmol/l; 2 h OGTT glucose 6.5 (2.0) mmol/l. In cohort 2 (diabetes), 66% ( n = 517) were treated by lifestyle modification and 34% ( n = 272) were treated with metformin plus lifestyle modification at enrolment. Fifty-eight per cent of participants in cohort 2 was male. Cohort 2 participants had the following characteristics at baseline: age 62 (8.1) years; BMI 30.5 (5.0) kg/m 2 ; fasting glucose 7.2 (1.4) mmol/l; 2 h glucose 8.6 (2.8) mmol/l. At the final follow-up examination, the participants’ clinical characteristics were as follows: fasting glucose 7.9 (2.0) mmol/l; 2 h mixed-meal tolerance test glucose 9.9 (3.4) mmol/l. Conclusions/interpretation The IMI DIRECT cohorts are intensely characterised, with a wide-variety of metabolically relevant measures assessed prospectively. We anticipate that the cohorts, made available through managed access, will provide a powerful resource for biomarker discovery, multivariate aetiological analyses and reclassification of patients for the prevention and treatment of type 2 diabetes. Electronic supplementary mater...
Genome-Wide Association Study (GWAS) Higher Blood pressure Arthritides Neuropsychiatric conditions Malignancies Lower Anaemias Lipidaemias Ischaemic heart disease Genetically higher central obesity Highlights Variants in HFE and TMPRSS6 are associated with higher liver iron. There is genetic evidence that higher central obesity causes higher liver iron. Liver iron variants are not organ specific and associate with multiple diseases.
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