Decoding protein methylation function with thermal stability analysis.

Protein methylation is an important modification beyond epigenetics. However, systems analyses of protein methylation lag behind compared to other modifications. Recently, thermal stability analyses have been developed which provide a proxy of a protein functional status. Here, we show that molecular and functional events closely linked to protein methylation can be revealed by the analysis of thermal stability. Using mouse embryonic stem cells as a model, we show that Prmt5 regulates mRNA binding proteins that are enriched in intrinsically disordered regions and involved in liquid-liquid phase separation mechanisms, including the formation of stress granules. Moreover, we reveal a non-canonical function of Ezh2 in mitotic chromosomes and the perichromosomal layer, and identify Mki67 as a putative Ezh2 substrate. Our approach provides an opportunity to systematically explore protein methylation function and represents a rich resource for understanding its role in pluripotency.

The MASTL/PP2A cell cycle kinase-phosphatase module restrains PI3K-Akt activity in an mTORC1-dependent manner.

The AKT-mTOR pathway is a central regulator of cell growth and metabolism. Upon sustained mTOR activity, AKT activity is attenuated by a feedback loop that restrains upstream signaling. However, how cells control the signals that limit AKT activity is not fully understood. Here, we show that MASTL/Greatwall, a cell cycle kinase that supports mitosis by phosphorylating the PP2A/B55 inhibitors ENSA/ARPP19, inhibits PI3K-AKT activity by sustaining mTORC1- and S6K1-dependent phosphorylation of IRS1 and GRB10. Genetic depletion of MASTL results in an inefficient feedback loop and AKT hyperactivity. These defects are rescued by the expression of phosphomimetic ENSA/ARPP19 or inhibition of PP2A/B55 phosphatases. MASTL is directly phosphorylated by mTORC1, thereby limiting the PP2A/B55-dependent dephosphorylation of IRS1 and GRB10 downstream of mTORC1. Downregulation of MASTL results in increased glucose uptake in vitro and increased glucose tolerance in adult mice, suggesting the relevance of the MASTL-PP2A/B55 kinase-phosphatase module in controlling AKT and maintaining metabolic homeostasis.

Biallelic germline mutations in MAD1L1 induce a syndrome of aneuploidy with high tumor susceptibility.

Germline mutations leading to aneuploidy are rare, and their tumor-promoting properties are mostly unknown at the molecular level. We report here novel germline biallelic mutations in MAD1L1, encoding the spindle assembly checkpoint (SAC) protein MAD1, in a 36-year-old female with a dozen of neoplasias. Functional studies demonstrated lack of full-length protein and deficient SAC response, resulting in ~30 to 40% of aneuploid blood cells. Single-cell RNA analysis identified mitochondrial stress accompanied by systemic inflammation with enhanced interferon and NFκB signaling both in aneuploid and euploid cells, suggesting a non-cell autonomous response. MAD1L1 mutations resulted in specific clonal expansions of γδ T cells with chromosome 18 gains and enhanced cytotoxic profile as well as intermediate B cells with chromosome 12 gains and transcriptomic signatures characteristic of leukemia cells. These data point to MAD1L1 mutations as the cause of a new variant of mosaic variegated aneuploidy with systemic inflammation and unprecedented tumor susceptibility.

Segmental undergrowth is associated with pathogenic variants in vascular malformation genes: A retrospective case-series study.

Segmental overgrowth has been widely described in patients with congenital vascular anomalies. However, segmental undergrowth has been poorly characterized, and no large series of patients have been published. We present the clinical and molecular characteristics a cohort of 37 patients with vascular malformations and segmental undergrowth. True undergrowth was only considered when the musculoskeletal system was involved to avoid confusion with other causes of segmental reduction, as in lipodystrophy or the long-term osteopenia seen in patients with Servelle-Martorell syndrome. Deep high-throughput sequencing was performed in tissue samples from 20 patients using a custom panel. We identified three groups: undergrowth associated with (1) venous, (2) capillary-venous, and (3) lymphatic-capillary-venous malformations. Congenital or early childhood onset undergrowth can occur with or without associated overgrowth. Different likely pathogenic or pathogenic variants were detected in 13 of 20 (65%) tissue samples in the PIK3CA, TEK, GNAQ, or GNA11 genes. In conclusion, the eponymous Servelle-Martorell syndrome should not be used as a synonym for undergrowth. Segmental undergrowth should be considered a characteristic associated with vascular malformations. Patients with PIK3CA variants show all different combinations of overgrowth and undergrowth. Thus, the term PROS (PIK3CA-related overgrowth spectrum) does not cover the entire spectrum.

CD9 inhibition reveals a functional connection of extracellular vesicle secretion with mitophagy in melanoma cells.

Tetraspanins are often used as Extracellular Vesicle (EV) detection markers because of their abundance on these secreted vesicles. However, data on their function on EV biogenesis are controversial and compensatory mechanisms often occur upon gene deletion. To overcome this handicap, we have compared the effects of tetraspanin CD9 gene deletion with those elicited by cytopermeable peptides with blocking properties against tetraspanin CD9. Both CD9 peptide or gene deletion reduced the number of early endosomes. CD9 peptide induced an increase in lysosome numbers, while CD9 deletion augmented the number of MVB and EV secretion, probably because of compensatory CD63 expression upregulation. In vivo, CD9 peptide delayed primary tumour cell growth and reduced metastasis size. These effects on cell proliferation were shown to be concomitant with an impairment in mitochondrial quality control. CD9 KO cells were able to compensate the mitochondrial malfunction by increasing total mitochondrial mass reducing mitophagy. Our data thus provide the first evidence for a functional connection of tetraspanin CD9 with mitophagy in melanoma cells.

CD69 Plays a Beneficial Role in Ischemic Stroke by Dampening Endothelial Activation.

RATIONALE: CD69 is an immunomodulatory molecule induced during lymphocyte activation. Following stroke, T-lymphocytes upregulate CD69 but its function is unknown. OBJECTIVE: We investigated whether CD69 was involved in brain damage following an ischemic stroke. METHODS AND RESULTS: We used adult male mice on the C57BL/6 or BALB/c backgrounds, including wild-type mice and CD69-/- mice, and CD69+/+ and CD69-/- lymphocyte-deficient Rag2-/- mice, and generated chimeric mice. We induced ischemia by transient or permanent middle cerebral artery occlusion. We measured infarct volume, assessed neurological function, and studied CD69 expression, as well as platelet function, fibrin(ogen) deposition, and VWF (von Willebrand factor) expression in brain vessels and VWF content and activity in plasma, and performed the tail-vein bleeding test and the carotid artery ferric chloride-induced thrombosis model. We also performed primary glial cell cultures and sorted brain CD45-CD11b-CD31+ endothelial cells for mRNA expression studies. We blocked VWF by intravenous administration of anti-VWF antibodies. CD69-/- mice showed larger infarct volumes and worse neurological deficits than the wild-type mice after ischemia. This worsening effect was not attributable to lymphocytes or other hematopoietic cells. CD69 deficiency lowered the time to thrombosis in the carotid artery despite platelet function not being affected. Ischemia upregulated Cd69 mRNA expression in brain endothelial cells. CD69-deficiency increased fibrin(ogen) accumulation in the ischemic tissue, and plasma VWF content and activity, and VWF expression in brain vessels. Blocking VWF reduced infarct volume and reverted the detrimental effect of CD69-/- deficiency. CONCLUSIONS: CD69 deficiency promotes a prothrombotic phenotype characterized by increased VWF and worse brain damage after ischemic stroke. The results suggest that CD69 acts as a downregulator of endothelial activation.

Thrombocytopenia-associated mutations in Ser/Thr kinase MASTL deregulate actin cytoskeletal dynamics in platelets.

MASTL, a Ser/Thr kinase that inhibits PP2A-B55 complexes during mitosis, is mutated in autosomal dominant thrombocytopenia. However, the connections between the cell-cycle machinery and this human disease remain unexplored. We report here that, whereas Mastl ablation in megakaryocytes prevented proper maturation of these cells, mice carrying the thrombocytopenia-associated mutation developed thrombocytopenia as a consequence of aberrant activation and survival of platelets. Activation of mutant platelets was characterized by hyperstabilized pseudopods mimicking the effect of PP2A inhibition and actin polymerization defects. These aberrations were accompanied by abnormal hyperphosphorylation of multiple components of the actin cytoskeleton and were rescued both in vitro and in vivo by inhibiting upstream kinases such as PKA, PKC, or AMPK. These data reveal an unexpected role of Mastl in actin cytoskeletal dynamics in postmitotic cells and suggest that the thrombocytopenia-associated mutation in MASTL is a pathogenic dominant mutation that mimics decreased PP2A activity resulting in altered phosphorylation of cytoskeletal regulatory pathways.

Role of sodium tungstate as a potential antiplatelet agent.

PURPOSE: Platelet inhibition is a key strategy in the management of atherothrombosis. However, the large variability in response to current strategies leads to the search for alternative inhibitors. The antiplatelet effect of the inorganic salt sodium tungstate (Na2O4W), a protein tyrosine phosphatase 1B (PTP1B) inhibitor, has been investigated in this study. METHODS: Wild-type (WT) and PTP1B knockout (PTP1B(-/-)) mice were treated for 1 week with Na2O4W to study platelet function with the platelet function analyzer PFA-100, a cone-and-plate analyzer, a flat perfusion chamber, and thrombus formation in vivo. Human blood aliquots were incubated with Na2O4W for 1 hour to measure platelet function using the PFA-100 and the annular perfusion chamber. Aggregometry and thromboelastometry were also performed. RESULTS: In WT mice, Na2O4W treatment prolonged closure times in the PFA-100 and decreased the surface covered (%SC) by platelets on collagen. Thrombi formed in a thrombosis mice model were smaller in animals treated with Na2O4W (4.6±0.7 mg vs 8.9±0.7 mg; P<0.001). Results with Na2O4W were similar to those in untreated PTP1B(-)/(-) mice (5.0±0.3 mg). Treatment of the PTP1B(-)/(-) mice with Na2O4W modified only slightly this response. In human blood, a dose-dependent effect was observed. At 200 µM, closure times in the PFA-100 were prolonged. On denuded vessels, %SC and thrombi formation (%T) decreased with Na2O4W. Neither the aggregating response nor the viscoelastic clot properties were affected. CONCLUSION: Na2O4W decreases consistently the hemostatic capacity of platelets, inhibiting their adhesive and cohesive properties under flow conditions in mice and in human blood, resulting in smaller thrombi. Although Na2O4W may be acting on platelet PTP1B, other potential targets should not be disregarded.

Vitamin K-dependent proteins GAS6 and Protein S and TAM receptors in patients of systemic lupus erythematosus: correlation with common genetic variants and disease activity.

INTRODUCTION: Growth arrest-specific gene 6 protein (GAS6) and protein S (ProS) are vitamin K-dependent proteins present in plasma with important regulatory functions in systems of response and repair to damage. They interact with receptor tyrosine kinases of the Tyro3, Axl and MerTK receptor tyrosine kinase (TAM) family, involved in apoptotic cell clearance (efferocytosis) and regulation of the innate immunity. TAM-deficient mice show spontaneous lupus-like symptoms. Here we tested the genetic profile and plasma levels of components of the system in patients with systemic lupus erythematosus (SLE), and compare them with a control healthy population. METHODS: Fifty SLE patients and 50 healthy controls with matched age, gender and from the same geographic area were compared. Genetic analysis was performed in GAS6 and the TAM receptor genes on SNPs previously identified. The concentrations of GAS6, total and free ProS, and the soluble forms of the three TAM receptors (sAxl, sMerTK and sTyro3) were measured in plasma from these samples. RESULTS: Plasma concentrations of GAS6 were higher and, total and free ProS were lower in the SLE patients compared to controls, even when patients on oral anticoagulant treatment were discarded. Those parameters correlated with SLE disease activity index (SLEDAI) score, GAS6 being higher in the most severe cases, while free and total ProS were lower. All 3 soluble receptors increased its concentration in plasma of lupus patients. CONCLUSIONS: The present study highlights that the GAS6/ProS-TAM system correlates in several ways with disease activity in SLE. We show here that this correlation is affected by common polymorphisms in the genes of the system. These findings underscore the importance of mechanism of regulatory control of innate immunity in the pathology of SLE.

Effect of the Gas6 c.834+7G>A polymorphism and the interaction of known risk factors on AMD pathogenesis in Hungarian patients.

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly in the developed world. Numerous genetic factors contribute to the development of the multifactorial disease. We performed a case-control study to assess the risk conferred by known and candidate genetic polymorphisms on the development of AMD. We searched for genetic interactions and for differences in dry and wet AMD etiology. We enrolled 213 patients with exudative, 67 patients with dry AMD and 106 age and ethnically matched controls. Altogether 12 polymorphisms in Apolipoprotein E, complement factor H, complement factor I, complement component 3, blood coagulation factor XIII, HTRA1, LOC387715, Gas6 and MerTK genes were tested. No association was found between either the exudative or the dry form and the polymorphisms in the Apolipoprotein E, complement factor I, FXIII and MerTK genes. Gas6 c.834+7G>A polymorphism was found to be significantly protective irrespective of other genotypes, reducing the odds of wet type AMD by a half (OR = 0.50, 95%CI: 0.26-0.97, p = 0.04). Multiple regression models revealed an interesting genetic interaction in the dry AMD subgroup. In the absence of C3 risk allele, mutant genotypes of both CFH and HTRA1 behaved as strongly significant risk factors (OR = 7.96, 95%CI: 2.39 = 26.50, p = 0.0007, and OR = 36.02, 95%CI: 3.30-393.02, p = 0.0033, respectively), but reduced to neutrality otherwise. The risk allele of C3 was observed to carry a significant risk in the simultaneous absence of homozygous CFH and HTRA1 polymorphisms only, in which case it was associated with a near-five-fold relative increase in the odds of dry type AMD (OR = 4.93, 95%CI: 1.98-12.25, p = 0.0006). Our results suggest a protective role of Gas6 c.834+7G>A polymorphism in exudative AMD development. In addition, novel genetic interactions were revealed between CFH, HTRA1 and C3 polymorphisms that might contribute to the pathogenesis of dry AMD.

Caracterización epidemiológica y factores de riesgo asociados a la peregrinación religiosa a Arabia Saudí. Resultados de una cohorte prospectiva 2008-2009 / Epidemiology and risk factors associated with religious pilgrimage to Saudi Arabia. Results of a prospective cohort 2008-2009

Introducción La peregrinación religiosa a Arabia Saudí o Hajj es un precepto básico en la doctrina islámica. Anualmente millones de peregrinos (un 5% procedente de la Unión Europea) se concentran en La Meca después del Ramadán, con los riesgos sanitarios que eso conlleva. Métodos Estudio observacional y prospectivo de una cohorte de peregrinos atendidos en visita de actividades preventivas predesplazamiento en la Unidad de Salud Internacional Metropolitana Norte (Santa Coloma de Gramenet, Barcelona, España) durante 2009-2010.ResultadosSe valoraron 193 peregrinos (135 hombres, 69,9%), con una edad media (DE) de 37,1 (16,9) años. Eran inmigrantes 176 (91,2%), originarios de Pakistán (54,9%), Marruecos (29%), Bangladesh (4,1%) y otros (7,2%). Se desplazaban a Arabia Saudí por una media (DE) de 16,3 (9,2) días; optaban por la peregrinación larga (Hajj) 80 (41,5%) y por la corta (Umra) 113 (58,5%). Presentaban antecedentes patológicos 29 (15%). Se obtuvo una cobertura vacunal superior al 75% para tétanos-difteria, antineumocócica y antimeningocócica tetravalente, y sólo de un 70,4% para la antigripal. Presentaron algún problema de salud 41 (13,5%), el 61% de ellos síntomas de vías respiratorias. Los factores de riesgo independientemente relacionados con presentar enfermedades fueron los días de estancia (odds ratio [OR]=1,06; intervalo de confianza del 95% [IC95%]: 1,01-1,11) y realizar el Hajj frente a la Umra (OR=1,08; IC95%: 1,07-1,12).Conclusiones Los peregrinos a Arabia Saudí procedentes de España son un colectivo fundamentalmente joven y sano. Presentaron un mayor número de enfermedades aquellos con estancias más largas (AU)

Introduction Religious pilgrimage to Saudi Arabia, or Hajj, is a basic tenet of the Islamic doctrine and, after Ramadan, annually represents the largest human concentration (with up to 5% of from the EU) around the world. Such a gathering entails health risks. Methods A prospective observational study was conducted of a cohort of pilgrims attended for pre-travel preventive activities in the North Metropolitan International Health Unit (Santa Coloma de Gramenet, Barcelona, Spain) from 2009-2010.ResultsA total of 193 pilgrims were assessed and 135 (69.9%) were men. Their mean age (SD) was 37.1 (16.9) years. Among the pilgrims, 176 (91.2%) were immigrants, mainly from Pakistan (54.9%), Morocco (29%), Bangladesh (4.1%) or other countries (7.2%). The pilgrims stayed in Saudi Arabia a mean (SD) of 16.3 (9.2) days. Eighty (41.5%) opted for the 1 month-long pilgrimage (Hajj) and 113 (58.5%) for the shorter Umra. One or more pathological antecedent was recorded in 29 (15%). Vaccination coverage was >75% for tetanus-diphtheria, pneumococcal and quadrivalent meningitis but was only 70.4% for influenza. After returning, 41 (13.5%) pilgrims reported some health problem; of these, 61% were respiratory tract symptoms. The risk factors independently correlated with the presence of diseases was the number of days in Saudi Arabia (OR=1.06; 95% CI: 1.01-1.11) and taking part in the Hajj compared with the Umra (OR=1.08; 95% CI: 1.07-1.12).Conclusions Religious pilgrims from Spain to Saudi Arabia are mainly young and healthy. Those with longer stays abroad contracted a higher number of diseases (AU)

[Epidemiology and risk factors associated with religious pilgrimage to Saudi Arabia. Results of a prospective cohort 2008-2009]. / Caracterización epidemiológica y factores de riesgo asociados a la peregrinación religiosa a Arabia Saudí. Resultados de una cohorte prospectiva 2008-2009.

INTRODUCTION: Religious pilgrimage to Saudi Arabia, or Hajj, is a basic tenet of the Islamic doctrine and, after Ramadan, annually represents the largest human concentration (with up to 5% of from the EU) around the world. Such a gathering entails health risks. METHODS: A prospective observational study was conducted of a cohort of pilgrims attended for pre-travel preventive activities in the North Metropolitan International Health Unit (Santa Coloma de Gramenet, Barcelona, Spain) from 2009-2010. RESULTS: A total of 193 pilgrims were assessed and 135 (69.9%) were men. Their mean age (SD) was 37.1 (16.9) years. Among the pilgrims, 176 (91.2%) were immigrants, mainly from Pakistan (54.9%), Morocco (29%), Bangladesh (4.1%) or other countries (7.2%). The pilgrims stayed in Saudi Arabia a mean (SD) of 16.3 (9.2) days. Eighty (41.5%) opted for the 1 month-long pilgrimage (Hajj) and 113 (58.5%) for the shorter Umra. One or more pathological antecedent was recorded in 29 (15%). Vaccination coverage was >75% for tetanus-diphtheria, pneumococcal and quadrivalent meningitis but was only 70.4% for influenza. After returning, 41 (13.5%) pilgrims reported some health problem; of these, 61% were respiratory tract symptoms. The risk factors independently correlated with the presence of diseases was the number of days in Saudi Arabia (OR=1.06; 95% CI: 1.01-1.11) and taking part in the Hajj compared with the Umra (OR=1.08; 95% CI: 1.07-1.12). CONCLUSIONS: Religious pilgrims from Spain to Saudi Arabia are mainly young and healthy. Those with longer stays abroad contracted a higher number of diseases.

GAS6 in systemic inflammatory diseases: with and without infection.

Vitamin K-dependent proteins are not only essential regulators of blood coagulation. A recent paper in Critical Care describes the levels of the vitamin K-dependent GAS6 and the soluble form of its receptor Axl in plasma from patients with sepsis of systemic inflammation. The results confirm that GAS6 is elevated during septicemia, but the fact that inflammatory conditions without infection produce a similar effect suggests it is inflammation that induces the synthesis of GAS6, rather than the interactions with bacteria or other infectious agents. The soluble form of the GAS6 receptor Axl was induced less compared with the effect observed in GAS6. This is important as the two proteins form an inactive complex in plasma, suggesting that a functional GAS6 form could be synthesized under these conditions. GAS6 has been proposed as a broad regulator of the innate immune response. GAS6 synthesis is therefore likely to be a regulatory mechanism during systemic inflammation. Recent advances provide the necessary tools for further research, including genetic screenings of the components of this system.

Association study between polymorphims in GAS6-TAM genes and carotid atherosclerosis.

Carotid atherosclerosis (CA) is one of the most common causes of stroke, and recent studies suggest that pathways initiated by the interaction of the plasma vitamin K-dependent protein GAS6 with the tyrosine kinase receptors TYRO3, AXL and MERTK (TAM) may have a relevant role in atherogenesis. Furthermore, our previous studies indicated an association between GAS6 and stroke. The aim of this study was to analyse the genetic association between SNPs and haplotypes in GAS6-TAM genes and CA. We performed a case-control study with 233 CA patients confirmed by nuclear magnetic resonance angiography and 202 patients who suffered from cardioembolic (non atherogenic) stroke. For all included subjects information on established risk factors was available. Genotyping of 16 selected tagSNPs was performed by real-time PCR, using either FRET or TaqMan probes. Adjusted logistic regression (LR) analyses indicated that rs2289743 in TYRO3 and rs869016 in MERTK were associated to CA, decreasing its risk (OR [95%CI]=0.39 [0.16-0.94] and OR [95%CI]=0.31 [0.14-0.69], respectively). Linkage disequilibrium results were consistent with the haplotype blocks described in HapMap and adjusted LR analyses revealed that the haplotype ACAA in MERTK , containing the minor allele of the associated SNP, was also associated to CA. No association was observed with GAS6 and AXL variants, which suggests that CA is not the mechanism underlying the reported association between GAS6 and stroke. The association between TYRO3 and MERTK variants and carotid atherosclerosis found in this study reinforces a physiological role of the GAS6-TAM pathway in atherogenesis.

Functional characterization of twelve natural PROS1 mutations associated with anticoagulant protein S deficiency.

BACKGROUND: The molecular mechanisms by which PROS1 mutations result in protein S deficiency are still unknown for many of the mutations, particularly for those that result in a premature termination codon. The aim of this study was to analyze the functional relevance on mRNA and protein expression of 12 natural PROS1 mutations associated with protein S deficiency. DESIGN AND METHODS: Five mutations were nonsense, three were small frameshift deletions, one was c.258,259AG>GT at the 3' end of exon 3, one was p.M640T and the last two were c.-7C>G and p.L15H, found in double heterozygosis as [c.-7C>G;44T>A]. The apparently neutral variant p.R233K was also analyzed. PROS1 cDNA was assessed by reverse transcriptase polymerase chain reaction of platelet mRNA. Expression of mutant proteins was determined by site-directed mutagenesis and analyses of transiently transfected PROS1 mutants in COS-7 cells. RESULTS: Only cDNA from the normal allele was observed from the five nonsense mutations, the frameshift deletion c.1731delT and from c.258,259AG>GT. Both the normal and the mutated alleles were observed from [c.-7C>G;44T>A], c.187,188delTG and p.M640T. Transient expression analyses of PROS1 mutants whose mRNA was normally expressed revealed greatly reduced secretion of p.L15H and c.1272delA, mild secretion values of p.M640T and normal secretion levels of c.-7C>G and, as expected, p.R233K. CONCLUSIONS: Whereas the main cause of quantitative protein S deficiency associated with missense mutations is defective synthesis, stability or secretion of the mutated protein, the main mechanism for the deficiency associated with mutations that generate a premature termination codon is not the synthesis of a truncated protein, but the exclusion of the mutated allele, probably by nonsense-mediated mRNA decay.

Molecular basis of protein S deficiency.

Protein S deficiency (PSD) has been the most difficult to study among the classical inherited thrombophilic factors. This is in part due to the peculiar biology of protein S (PS), which has an anticoagulant role but no enzymatic activity, and because it interacts with plasma components that function in both haemostasis and inflammation. Clinically, it also has been difficult to define and standardise valuable assays to determine PS status and implication in thrombosis. Despite these drawbacks, at present heterozygous PS deficiency is well established as an autosomal dominant trait associated with an increased risk of thrombosis from data on familial and population studies. Almost two-hundred mutations have been characterised in PROS1, and approximately 30% of them have been characterised in vitro, clarifying the mechanisms leading to PSD. Furthermore, recent studies on the presence of large deletions in PROS1 have increased the number of PSD associated to PROS1 mutations. Finally, the discovery of new functions for PS, both in the anticoagulant system as well as in the interaction with cellular components through receptor tyrosine kinases, is broadening the importance of this molecule in the context of biomedicine.

Association of specific haplotypes of GAS6 gene with stroke.

The product of the growth arrest-specific gene 6 (GAS6), a ligand for tyrosine kinase receptors, is a vitamin K-dependent protein, structurally related to anticoagulant protein S. Gas6-deficient mice are protected against thrombosis, demonstrating the importance of this protein in the cardiovascular system. In a preliminary study on GAS6 polymorphisms and atherothrombotic disease we found an association between the AA genotype of the c.834 + 7G > A GAS6 polymorphism and stroke. In order to further explore this association by considering GAS6 haplotypes and the main stroke subtypes, 457 patients with ischemic stroke, 199 with hemorrhagic stroke and 150 asymptomatic controls were genotyped for eight GAS6 polymorphisms and other genetic markers in the same genome region. Association was measured by logistic regression analysis. The THESIAS program was used to measure linkage disequilibrium and haplotype frequencies. In univariate analysis, the GAS6 c.834 + 7AA genotype was found associated with decreased risk for stroke (OR: 0.59; 95%CI: 0.37-0.93). After adjustment for vascular risk factors, association was maintained when stroke subtypes affecting the microvasculature such as lacunar stroke and deep haemorrhage, were grouped together (OR: 0.44; 95%CI: 0.21-0.90). Furthermore, haplotype analysis revealed that association was even stronger when the c.834 + 7A allele was present in a specific haplotype (CACA) of four GAS6 polymorphisms. From these results we conclude that the A allele of the GAS6 c.834 + 7G > A polymorphism and more specifically, the CACA haplotype, is less prevalent in patients with stroke, suggesting a protective role for stroke of this haplotype.