A genome-wide expression quantitative trait loci analysis of proprotein convertase subtilisin/kexin enzymes identifies a novel regulatory gene variant for FURIN expression and blood pressure

The Role of Furin and Its Therapeutic Potential in Cardiovascular Disease Risk

Furin is an important proteolytic enzyme, converting several proteins from inactive precursors to their active forms. Recently, proteo-genomic analyses in European and East Asian populations suggested a causal association of furin with ischaemic heart disease, and there is growing interest in its role in cardiovascular disease (CVD) aetiology. In this narrative review, we present a critical appraisal of evidence from population studies to assess furin's role in CVD risk and potential as a drug target for CVD. Whilst most observational studies report positive associations between furin expression and CVD risk, some studies report opposing effects, which may reflect the complex biological roles of furin and its substrates. Genetic variation in FURIN is also associated with CVD and its risk factors. We found no evidence of current clinical development of furin as a drug target for CVD, although several phase 1 and 2 clinical trials of furin inhibitors as a type of cancer immunotherapy have been completed. The growing field of proteo-genomics in large-scale population studies may inform the future development of furin and other potential drug targets to improve the treatment and prevention of CVD.

Associative gene networks reveal novel candidates important for ADHD and dyslexia comorbidity

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is commonly associated with developmental dyslexia (DD), which are both prevalent and complicated pediatric neurodevelopmental disorders that have a significant influence on children's learning and development. Clinically, the comorbidity incidence of DD and ADHD is between 25 and 48%. Children with DD and ADHD may have more severe cognitive deficiencies, a poorer level of schooling, and a higher risk of social and emotional management disorders. Furthermore, patients with this comorbidity are frequently treated for a single condition in clinical settings, and the therapeutic outcome is poor. The development of effective treatment approaches against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and treatment. In this study, we developed bioinformatical methodology for the analysis of the comorbidity of these two diseases. As such, the search for candidate genes related to the comorbid conditions of ADHD and DD can help in elucidating the molecular mechanisms underlying the comorbid condition, and can also be useful for genotyping and identifying new drug targets.

RESULTS

Using the ANDSystem tool, the reconstruction and analysis of gene networks associated with ADHD and dyslexia was carried out. The gene network of ADHD included 599 genes/proteins and 148,978 interactions, while that of dyslexia included 167 genes/proteins and 27,083 interactions. When the ANDSystem and GeneCards data were combined, a total of 213 genes/proteins for ADHD and dyslexia were found. An approach for ranking genes implicated in the comorbid condition of the two diseases was proposed. The approach is based on ten criteria for ranking genes by their importance, including relevance scores of association between disease and genes, standard methods of gene prioritization, as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analyzed genes. Among the top 20 genes with the highest priority DRD2, DRD4, CNTNAP2 and GRIN2B are mentioned in the literature as directly linked with the comorbidity of ADHD and dyslexia. According to the proposed approach, the genes OPRM1, CHRNA4 and SNCA had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the most relevant genes are involved in biological processes related to signal transduction, positive regulation of transcription from RNA polymerase II promoters, chemical synaptic transmission, response to drugs, ion transmembrane transport, nervous system development, cell adhesion, and neuron migration.

CONCLUSIONS

The application of methods of reconstruction and analysis of gene networks is a powerful tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance for the comorbid condition of ADHD and dyslexia was employed to predict genes that play key roles in the development of the comorbid condition. The results can be utilized to plan experiments for the identification of novel candidate genes and search for novel pharmacological targets.

Multi-ancestry study of the genetics of problematic alcohol use in >1 million individuals

Problematic alcohol use (PAU) is a leading cause of death and disability worldwide. To improve our understanding of the genetics of PAU, we conducted a large cross-ancestry meta-analysis of PAU in 1,079,947 individuals. We observed a high degree of cross-ancestral similarity in the genetic architecture of PAU and identified 110 independent risk variants in within- and cross-ancestry analyses. Cross-ancestry fine-mapping improved the identification of likely causal variants. Prioritizing genes through gene expression and/or chromatin interaction in brain tissues identified multiple genes associated with PAU. We identified existing medications for potential pharmacological studies by drug repurposing analysis. Cross-ancestry polygenic risk scores (PRS) showed better performance in independent sample than single-ancestry PRS. Genetic correlations between PAU and other traits were observed in multiple ancestries, with other substance use traits having the highest correlations. The analysis of diverse ancestries contributed significantly to the findings, and fills an important gap in the literature.

FURIN gene variants (rs6224/rs4702) as potential markers of deat hand cardiovascular traits in severe COVID-19

Furin is a protease that plays a key role in the infection cycle of SARS‐CoV‐2 by cleaving the viral proteins during the virus particle assembly. In addition, Furin regulates several physiological processes related to cardio‐metabolic traits. DNA variants in the FURIN gene are candidates to regulate the risk of developing these traits as well as the susceptibility to severe COVID‐19. We genotyped two functional FURIN variants (rs6224/rs4702) in 428 COVID‐19 patients in the intensive care unit. The association with death (N = 106) and hypertension, diabetes, and hyperlipidaemia was statistically evaluated. The risk of death was associated with age, hypertension, and hypercholesterolemia. The two FURIN alleles linked to higher expression (rs6224 T and rs4702 A) were significantly increased in the death cases (odds ratio= 1.40 and 1.43). Homozygosis for the two high expression genotypes (rs6224 TT and rs4702 AA) and for the T‐A haplotype was associated with an increased risk of hypercholesterolemia. In the multiple logistic regression both, hypercholesterolemia and the TT + AA genotype were significantly associated with death. In conclusion, besides its association with hypercholesterolemia, FURIN variants might be independent risk factors for the risk of death among COVID‐19 patients.

Furin plays an important role in the life‐cycle of SARS‐CoV‐2

Furin activity might regulate the risk for cardiovascular traits, such as hypertension and hypercholesterolemia.

Two functional FURIN variants were associated with the risk of death among critical COVID‐19 patients.

The observed association with mortality was independent of higher cholesterol levels.

FURIN gene variants might be predictors of COVID‐19 severity and mortaility.

The association between plasma furin and cardiovascular events after acute myocardial infarction

Background

Furin is the key enzyme involved in the cleavage of pro-BNP and plays a critical role in the cardiovascular system through its involvement in lipid metabolism, blood pressure regulation and the formation of atheromatous plaques. NT-proBNP and recently, corin, also a key enzyme in the cleavage of pro-BNP, have been accepted as predictors of prognosis after acute myocardial infarction (AMI). This cohort study was conducted to investigate the relationship between plasma furin and the prognostic outcomes of AMI patients.

Methods

In total, 1100 AMI patients were enrolled in the study and their plasma furin concentrations were measured. The primary endpoint was major adverse cardiac events (MACE), a composite of cardiovascular (CV) death, non-fatal myocardial infarction (MI) and non-fatal stroke. The associations between plasma furin concentration and AMI outcomes were explored using Kaplan–Meier curves and multivariate Cox regression analysis.

Results

The results showed a slight increase in mean cTNT in patients with higher furin concentrations (P = 0.016). Over a median follow-up of 31 months, multivariate Cox regression analysis indicated that plasma furin was not significantly associated with MACE (HR 1.01; 95% CI 0.93–1.06; P = 0.807) after adjustment for potential conventional risk factors. However, plasma furin was associated with non-fatal MI (HR 1.09; 95% CI 1.01–1.17; P = 0.022) in the fully adjusted model. Subgroup analyses indicated no relationship between plasma furin and MACE in different subgroups.

Conclusions

This study found no association between plasma furin and risk of MACE. Thus, plasma furin may not be a useful predictor of poor prognosis after AMI. However, higher levels of plasma furin may be associated with a higher risk of recurrent non-fatal MI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02029-y.

Altered serum soluble furin and prorenin receptor levels in pregnancies with pre-eclampsia and fetal growth restriction

OBJECTIVE

The proprotein convertase furin is known to be involved in the processing of pro-B-type natriuretic peptide (proBNP) and prorenin receptor (PRR), suggesting that it has a potential function in blood pressure regulation. We investigated the role of furin in the etiology of pre-eclampsia and its related disorder, unexplained fetal growth restriction (FGR) without hypertension.

METHODS

We evaluated serum and placental furin levels in pre-eclampsia, FGR and uncomplicated pregnancy. Additionally, we investigated the correlation between the serum furin levels and products of furin enzymatic activity or clinical parameters.

RESULTS

We demonstrated that the maternal circulation in cases of pre-eclampsia and FGR had lower levels of soluble furin than uncomplicated pregnancies. Both NT-proBNP and soluble PRR were elevated in pre-eclampsia, whereas only soluble PRR was at higher levels in unexplained FGR. Linear regression analysis revealed a negative correlation between the serum furin level and that of NT-proBNP or soluble PRR. While we observed that the serum furin or soluble PRR level correlated with blood pressure, a stronger correlation was observed with birth and placental weights. Further to this, the FURIN mRNA levels were significantly reduced in placental pre-eclamptic placentas as well as in FGR cases.

CONCLUSION

These data suggest the possibility that reduced levels of furin may be the result of a negative feedback from the activation of the renin-angiotensin pathway that leads to feto-placental dysfunction with or without maternal hypertension. This may represent an etiologic pathway of pre-eclampsia and unexplained FGR.

Mouse Models of Human Proprotein Convertase Insufficiency

The kexin-like proprotein convertases perform the initial proteolytic cleavages that ultimately generate a variety of different mature peptide and proteins, ranging from brain neuropeptides to endocrine peptide hormones, to structural proteins, among others. In this review, we present a general introduction to proprotein convertase structure and biochemistry, followed by a comprehensive discussion of each member of the kexin-like subfamily of proprotein convertases. We summarize current knowledge of human proprotein convertase insufficiency syndromes, including genome-wide analyses of convertase polymorphisms, and compare these to convertase null and mutant mouse models. These mouse models have illuminated our understanding of the roles specific convertases play in human disease and have led to the identification of convertase-specific substrates; for example, the identification of procorin as a specific PACE4 substrate in the heart. We also discuss the limitations of mouse null models in interpreting human disease, such as differential precursor cleavage due to species-specific sequence differences, and the challenges presented by functional redundancy among convertases in attempting to assign specific cleavages and/or physiological roles. However, in most cases, knockout mouse models have added substantively both to our knowledge of diseases caused by human proprotein convertase insufficiency and to our appreciation of their normal physiological roles, as clearly seen in the case of the furin, proprotein convertase 1/3, and proprotein convertase 5/6 mouse models. The creation of more sophisticated mouse models with tissue- or temporally-restricted expression of specific convertases will improve our understanding of human proprotein convertase insufficiency and potentially provide support for the emerging concept of therapeutic inhibition of convertases.

Germline Genetic Variants of Viral Entry and Innate Immunity May Influence Susceptibility to SARS-CoV-2 Infection: Toward a Polygenic Risk Score for Risk Stratification

The ongoing COVID-19 pandemic caused by the novel coronavirus, SARS-CoV-2 has affected all aspects of human society with a special focus on healthcare. Although older patients with preexisting chronic illnesses are more prone to develop severe complications, younger, healthy individuals might also exhibit serious manifestations. Previous studies directed to detect genetic susceptibility factors for earlier epidemics have provided evidence of certain protective variations. Following SARS-CoV-2 exposure, viral entry into cells followed by recognition and response by the innate immunity are key determinants of COVID-19 development. In the present review our aim was to conduct a thorough review of the literature on the role of single nucleotide polymorphisms (SNPs) as key agents affecting the viral entry of SARS-CoV-2 and innate immunity. Several SNPs within the scope of our approach were found to alter susceptibility to various bacterial and viral infections. Additionally, a multitude of studies confirmed genetic associations between the analyzed genes and autoimmune diseases, underlining the versatile immune consequences of these variants. Based on confirmed associations it is highly plausible that the SNPs affecting viral entry and innate immunity might confer altered susceptibility to SARS-CoV-2 infection and its complex clinical consequences. Anticipating several COVID-19 genomic susceptibility loci based on the ongoing genome wide association studies, our review also proposes that a well-established polygenic risk score would be able to clinically leverage the acquired knowledge.

Diseases with health disparities as drivers of COVID-19 outcome

The COVID-19 pandemic has forced our society to come face to face with complex issues that were once theoretical but are now being played out in real time. As data from the pandemic accumulates, it is clear that COVID-19 is impacting some parts of society more than others. Unfortunately, there is an almost complete overlap between COVID-19 risk factors and conditions that are already represented as health disparities, such as hypertension, diabetes, heart disease, lung disease and immune disorders. In this review, we discuss our current understanding of the physiological and pathophysiological pathways that link these diseases to COVID-19 outcome. An increased awareness of the factors underlying this issue, both societal and medical, is needed to understand the long-term implications and possible solutions needed going forward.

LRRTM4 and PCSK5 Genetic Polymorphisms as Markers for Cognitive Impairment in A Hypotensive Aging Population: A Genome-Wide Association Study in Taiwan

Hypotension can affect cerebral perfusion and worsen cognitive outcomes. The prevalence of low blood pressure (BP) rises with increasing age. To our knowledge, no study has examined the genetic biomarkers for hypotension-related cognitive impairment (CI) yet. Utilizing the population-based genome-wide study of the Taiwan Biobank containing the data of 2533 healthy aging subjects, we found after adjustments for age, sex, education years, and principal components at a suggestive level of 1 × 10⁻⁵ that minor alleles of leucine rich repeat transmembrane neuronal 4 (LRRTM4) (rs13388459, rs1075716, rs62171995, rs17406146, rs2077823, and rs62170897), proprotein convertase subtilisin/kexin type 5 (PCSK5) (rs10521467), and the intergenic variation rs117129097 (the nearby gene: TMEM132C) are risk factors for CI in hypotensive subjects. Except for rs117129097, these single nucleotide polymorphisms (SNPs) were not markers per se for CI or for BP regulation. However, we found a suggestive interaction effect between each of the eight SNPs and hypotension on CI risk. In the hypotensive participants, those carrying minor alleles were associated with a higher incidence of CI in an additive manner than were those carrying major alleles (2 × 10⁻⁴ to 9 × 10⁻⁷). Intensive BP lowering in elderly patients carrying a minor allele of the eight identified SNPs should raise cautions to prevent a potential treatment-induced neurodegeneration.

Genetic and epigenetic regulation of human aging and longevity

Here we summarize the latest data on genetic and epigenetic contributions to human aging and longevity. Whereas environmental and lifestyle factors are important at younger ages, the contribution of genetics appears more important in reaching extreme old age. Genome-wide studies have implicated ~57 gene loci in lifespan. Epigenomic changes during aging profoundly affect cellular function and stress resistance. Dysregulation of transcriptional and chromatin networks is likely a crucial component of aging. Large-scale bioinformatic analyses have revealed involvement of numerous interaction networks. As the young well-differentiated cell replicates into eventual senescence there is drift in the highly regulated chromatin marks towards an entropic middle-ground between repressed and active, such that genes that were previously inactive "leak". There is a breakdown in chromatin connectivity such that topologically associated domains and their insulators weaken, and well-defined blocks of constitutive heterochromatin give way to generalized, senescence-associated heterochromatin, foci. Together, these phenomena contribute to aging.

Serum furin as a biomarker of high blood pressure: findings from a longitudinal study in Chinese adults

The cardiovascular protective role of furin has been suggested by some animal-based studies but has not been well studied in humans. Therefore, the objective of this study was to examine the prospective association between serum furin and high blood pressure in a longitudinal cohort of Chinese adults. Leveraging a longitudinal prospective cohort with blood pressure examined twice on average 4 years apart, we systemically examined the cross-sectional, longitudinal, and prospective associations of baseline serum furin with blood pressure and incident hypertension. Conventional risk factors, including age, sex, education level, cigarette smoking, alcohol consumption, BMI, fasting glucose, and lipids, were controlled. All participants included were free of cardiovascular and kidney disease at baseline. The cross-sectional analysis of 2312 participants (mean age 53 years) revealed that individuals with the lowest quartile of serum furin had average systolic, diastolic, and mean arterial blood pressures that were 2.58, 1.38, and 1.61 mmHg higher, respectively, than the corresponding pressures in individuals with the highest quartile (all P < 0.001). These negative associations remained significant after controlling for the dynamic risk profiles during follow-up in the longitudinal analysis. The prospective analysis of 1088 participants free of prevalent hypertension at baseline revealed that compared with participants with the highest quartile of serum furin, those with the lowest quartile had a 46% increased risk of incident hypertension (HR = 1.46, P = 0.003). These results indicate that lower serum furin is significantly associated with higher blood pressure and predicts an increased future risk of developing hypertension in Chinese adults. Furin may be a protective factor or marker of hypertension.

Discovery of mitochondrial DNA variants associated with genome-wide blood cell gene expression: a population-based mtDNA sequencing study

The effect of mitochondrial DNA (mtDNA) variation on peripheral blood transcriptomics in health and disease is not fully known. Sex-specific mitochondrially controlled gene expression patterns have been shown in Drosophila melanogaster but in humans, evidence is lacking. Functional variation in mtDNA may also have a role in the development of type 2 diabetes and its precursor state, i.e. prediabetes. We examined the associations between mitochondrial single-nucleotide polymorphisms (mtSNPs) and peripheral blood transcriptomics with a focus on sex- and prediabetes-specific effects. The genome-wide blood cell expression data of 19 637 probes, 199 deep-sequenced mtSNPs and nine haplogroups of 955 individuals from a population-based Young Finns Study cohort were used. Significant associations were identified with linear regression and analysis of covariance. The effects of sex and prediabetes on the associations between gene expression and mtSNPs were studied using random-effect meta-analysis. Our analysis identified 53 significant expression probe-mtSNP associations after Bonferroni correction, involving 7 genes and 31 mtSNPs. Eight probe-mtSNP signals remained independent after conditional analysis. In addition, five genes showed differential expression between haplogroups. The meta-analysis did not show any significant differences in linear model effect sizes between males and females but identified the association between the OASL gene and mtSNP C16294T to show prediabetes-specific effects. This study pinpoints new independent mtSNPs associated with peripheral blood transcriptomics and replicates six previously reported associations, providing further evidence of the mitochondrial genetic control of blood cell gene expression. In addition, we present evidence that prediabetes might lead to perturbations in mitochondrial control.

FURIN variant associations with postexercise hypotension are intensity and race dependent

FURIN is a proprotein convertase subtilisin/kexin enzyme important in pro-renin receptor processing, and FURIN (furin, paired basic amino acid cleaving enzyme) variants are involved in multiple aspects of blood pressure (BP) regulation. Therefore, we examined associations among FURIN variants and the immediate blood pressure (BP) response to bouts of aerobic exercise, termed postexercise hypotension (PEH). Obese (30.9 ± 3.6 kg  m-2 ) Black- (n = 14) and White- (n = 9) adults 42.0 ± 9.8 year with hypertension (139.8 ± 10.4/84.6 ± 6.2 mmHg) performed three random experiments: bouts of vigorous (VIGOROUS) and moderate (MODERATE) intensity cycling and control. Subjects were then attached to an ambulatory BP monitor for 19 h. We performed deep-targeted exon sequencing with the Illumina TruSeq Custom Amplicon kit. FURIN genotypes were coded as the number of minor alleles (#MA) and selected for additional statistical analysis based upon Bonferonni or Benjamini-Yekutieli multiple testing corrected P-values under time-adjusted linear models for 19 hourly BP measurements. After VIGOROUS over 19 h, as FURIN #MA increased in rs12917264 (P = 2.4E-04) and rs75493298 (P = 6.4E-04), systolic BP (SBP) decreased 30.4-33.7 mmHg; and in rs12917264 (P = 1.6E-03) and rs75493298 (P = 9.7E-05), diastolic BP (DBP) decreased 17.6-20.3 mmHg among Blacks only. In addition, after MODERATE over 19 h in FURIN rs74037507 (P = 8.0E-04), as #MA increased, SBP increased 20.8 mmHg among Blacks only. Whereas, after MODERATE over the awake hours in FURIN rs1573644 (P = 6.2E-04), as #MA increased, DBP decreased 12.5 mmHg among Whites only. FURIN appears to exhibit intensity and race-dependent associations with PEH that merit further exploration among a larger, ethnically diverse sample of adults with hypertension.

Increased expression of the proprotein convertase enzyme FURIN in rheumatoid arthritis

OBJECTIVE

FURIN is a proprotein convertase enzyme that inhibits the proinflammatory function of T cells and myeloid cells. Elevated FURIN expression levels have been reported in immune-mediated diseases, such as primary Sjögren's syndrome. Here, we investigated the levels of FURIN in peripheral blood (PB) and synovial fluid (SF) leucocytes from patients with rheumatoid arthritis (RA).

METHOD

FURIN mRNA expression in PB and SF cells was determined by quantitative reverse transcription-polymerase chain reaction and FURIN plasma levels were measured using enzyme-linked immunosorbent assay. Associations between FURIN levels and demographic and clinical characteristics of the patients were determined.

RESULTS

FURIN levels were significantly elevated in PB and SF mononuclear cells, T cells, and monocytes from RA patients compared to healthy controls. High FURIN levels were significantly associated with the prevailing prednisolone treatment, higher prednisolone doses, and increased C-reactive protein levels and Health Assessment Questionnaire values.

CONCLUSION

FURIN is significantly upregulated in RA PB and SF leucocytes, suggesting that it may have a role in the pathogenesis of RA. In addition, our results suggest that elevated FURIN expression is associated with the indicators of more severe RA.

Rare Copy Number Variants Identify Novel Genes in Sporadic Total Anomalous Pulmonary Vein Connection

Total anomalous pulmonary venous connection (TAPVC) is a rare congenital heart anomaly. Several genes have been associated TAPVC but the mechanisms remain elusive. To search novel CNVs and candidate genes, we screened a cohort of 78 TAPVC cases and 100 healthy controls for rare copy number variants (CNVs) using whole exome sequencing (WES). Then we identified pathogenic CNVs by statistical comparisons between case and control groups. After that, we identified altogether eight pathogenic CNVs of seven candidate genes (PCSK7, RRP7A, SERHL, TARP, TTN, SERHL2, and NBPF3). All these seven genes have not been described previously to be related to TAPVC. After network analysis of these candidate genes and 27 known pathogenic genes derived from the literature and publicly database, PCSK7 and TTN were the most important genes for TAPVC than other genes. Our study provides novel candidate genes potentially related to this rare congenital birth defect (CHD) which should be further fundamentally researched and discloses the possible molecular pathogenesis of TAPVC.

Myeloid cell expressed proprotein convertase FURIN attenuates inflammation

The proprotein convertase enzyme FURIN processes immature pro-proteins into functional end- products. FURIN is upregulated in activated immune cells and it regulates T-cell dependent peripheral tolerance and the Th1/Th2 balance. FURIN also promotes the infectivity of pathogens by activating bacterial toxins and by processing viral proteins. Here, we evaluated the role of FURIN in LysM+ myeloid cells in vivo. Mice with a conditional deletion of FURIN in their myeloid cells (LysMCre-fur^(fl/fl)) were healthy and showed unchanged proportions of neutrophils and macrophages. Instead, LysMCre-fur^(fl/fl) mice had elevated serum IL-1β levels and reduced numbers of splenocytes. An LPS injection resulted in accelerated mortality, elevated serum pro-inflammatory cytokines and upregulated numbers of pro-inflammatory macrophages. A genome-wide gene expression analysis revealed the overexpression of several pro-inflammatory genes in resting FURIN-deficient macrophages. Moreover, FURIN inhibited Nos2 and promoted the expression of Arg1, which implies that FURIN regulates the M1/M2-type macrophage balance. FURIN was required for the normal production of the bioactive TGF-β1 cytokine, but it inhibited the maturation of the inflammation-provoking TACE and Caspase-1 enzymes. In conclusion, FURIN has an anti-inflammatory function in LysM+ myeloid cells in vivo.

Novel candidate genes important for asthma and hypertension comorbidity revealed from associative gene networks

BACKGROUND

Hypertension and bronchial asthma are a major issue for people's health. As of 2014, approximately one billion adults, or ~ 22% of the world population, have had hypertension. As of 2011, 235-330 million people globally have been affected by asthma and approximately 250,000-345,000 people have died each year from the disease. The development of the effective treatment therapies against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and their treatment. Hence, in this study the bioinformatical methodology for the analysis of the comorbidity of these two diseases have been developed. As such, the search for candidate genes related to the comorbid conditions of asthma and hypertension can help in elucidating the molecular mechanisms underlying the comorbid condition of these two diseases, and can also be useful for genotyping and identifying new drug targets.

RESULTS

Using ANDSystem, the reconstruction and analysis of gene networks associated with asthma and hypertension was carried out. The gene network of asthma included 755 genes/proteins and 62,603 interactions, while the gene network of hypertension - 713 genes/proteins and 45,479 interactions. Two hundred and five genes/proteins and 9638 interactions were shared between asthma and hypertension. An approach for ranking genes implicated in the comorbid condition of two diseases was proposed. The approach is based on nine criteria for ranking genes by their importance, including standard methods of gene prioritization (Endeavor, ToppGene) as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analysed genes. According to the proposed approach, the genes IL10, TLR4, and CAT had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the list of top genes is enriched with apoptotic genes and genes involved in biological processes related to the functioning of central nervous system.

CONCLUSIONS

The application of methods of reconstruction and analysis of gene networks is a productive tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance to the comorbid condition of asthma and hypertension was employed that resulted in prediction of 10 genes, playing the key role in the development of the comorbid condition. The results can be utilised to plan experiments for identification of novel candidate genes along with searching for novel pharmacological targets.

Blood pathway analyses reveal differences between prediabetic subjects with or without dyslipidaemia. The Cardiovascular Risk in Young Finns Study

BACKGROUND

Prediabetes often occurs together with dyslipidaemia, which is paradoxically treated with statins predisposing to type 2 diabetes mellitus. We examined peripheral blood pathway profiles in prediabetic subjects with (PR_D ) and without dyslipidaemia (PR₀ ) and compared these to nonprediabetic controls without dyslipidaemia (C₀ ).

METHODS

The participants were from the Cardiovascular Risk in Young Finns Study, including 1240 subjects aged 34 to 49 years. Genome-wide expression data of peripheral blood and gene set enrichment analysis were used to investigate the differentially expressed genes and enriched pathways between different subtypes of prediabetes.

RESULTS

Pathways for cholesterol synthesis, interleukin-12-mediated signalling events, and downstream signalling in naïve CD8+ T-cells were upregulated in the PR₀ group in comparison with controls (C₀ ). The upregulation of these pathways was independent of waist circumference, blood pressure, smoking status, and insulin. Adjustment for CRP left the CD8+ T-cell signalling and interleukin-12-mediated signalling event pathway upregulated. The cholesterol synthesis pathway was also upregulated when all prediabetic subjects (PR₀ and PR_D ) were compared with the nonprediabetic control group. No pathways were upregulated or downregulated when the PR_D group was compared with the C₀ group. Five genes in the PR₀ group and 1 in the PR_D group were significantly differentially expressed in comparison with the C₀ group.

CONCLUSIONS

Blood cell gene expression profiles differ significantly between prediabetic subjects with and without dyslipidaemia. Whether this classification may be used in detection of prediabetic individuals at a high risk of cardiovascular complications remains to be examined.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

Proprotein convertase inhibition: Paralyzing the cell's master switches

Proprotein convertases are serine proteases responsible for the cleavage and subsequent activation of protein substrates, many of them relevant for the development of an ample variety of diseases. Seven of the PCs, including furin and PACE4, recognize and hydrolyze the C-terminal end of the general sequence RXRR/KXR, whereas PCSK-9 recognizes a series of non-basic amino acids. In some systems, PC-mediated substrate activation results in the development of pathological processes, such as cancer, endocrinopathies, and cardiovascular and infectious diseases. After establishing PCs as relevant contributors to disease processes, research efforts were directed towards the development of inhibition strategies, including small and large molecules, anti-sense therapies, and antibody-based therapies. Most of these inhibitors mimic the consensus sequence of PCs, blocking the active site in a competitive manner. The most promising inhibitors were designed as bioengineered proteins; however, some non-protein and peptidomimetic agents have also proved to be effective. These efforts led to the design of pre-clinical studies and clinical trials utilizing inhibitors to PCs. Although the initial studies were performed using non-selective PCs inhibitors, such as CMK, the search for more specific, and compartmentalized selective inhibitors resulted in specific activities ascribed to some, but not all of the PCs. For instance, PACE4 inhibitors were effective in decreasing prostate cancer cell proliferation, and neovascularization. Decreased metastatic ovarian cancer utilizing furin inhibitors represents one of the major endeavors, currently in a phase II trial stage. Antibodies targeting PCSK-9 decreased significantly the levels of HDL-cholesterol, in a phase III trial. The study of Proprotein convertases has reached a stage of maturity. New strategies based on the alteration of their activity at the cellular and clinical level represent a promising experimental pharmacology field. The development of allosteric inhibitors, or specific agents directed against individual PCs is one of the challenges to be unraveled in the future.

Differentially expressed genes and canonical pathway expression in human atherosclerotic plaques - Tampere Vascular Study

Cardiovascular diseases due to atherosclerosis are the leading cause of death globally. We aimed to investigate the potentially altered gene and pathway expression in advanced peripheral atherosclerotic plaques in comparison to healthy control arteries. Gene expression analysis was performed (Illumina HumanHT-12 version 3 Expression BeadChip) for 68 advanced atherosclerotic plaques (15 aortic, 29 carotid and 24 femoral plaques) and 28 controls (left internal thoracic artery (LITA)) from Tampere Vascular Study. Dysregulation of individual genes was compared to healthy controls and between plaques from different arterial beds and Ingenuity pathway analysis was conducted on genes with a fold change (FC) > ±1.5 and false discovery rate (FDR) < 0.05. 787 genes were significantly differentially expressed in atherosclerotic plaques. The most up-regulated genes were osteopontin and multiple MMPs, and the most down-regulated were cell death-inducing DFFA-like effector C and A (CIDEC, CIDEA) and apolipoprotein D (FC > 20). 156 pathways were differentially expressed in atherosclerotic plaques, mostly inflammation-related, especially related with leukocyte trafficking and signaling. In artery specific plaque analysis 50.4% of canonical pathways and 41.2% GO terms differentially expressed were in common for all three arterial beds. Our results confirm the inflammatory nature of advanced atherosclerosis and show novel pathway differences between different arterial beds.

Genome-wide Association Study Identifies 27 Loci Influencing Concentrations of Circulating Cytokines and Growth Factors

Circulating cytokines and growth factors are regulators of inflammation and have been implicated in autoimmune and metabolic diseases. In this genome-wide association study (GWAS) of up to 8,293 Finns we identified 27 genome-widely significant loci (p < 1.2 × 10^-9) for one or more cytokines. Fifteen of the associated variants had expression quantitative trait loci in whole blood. We provide genetic instruments to clarify the causal roles of cytokine signaling and upstream inflammation in immune-related and other chronic diseases. We further link inflammatory markers with variants previously associated with autoimmune diseases such as Crohn disease, multiple sclerosis, and ulcerative colitis and hereby elucidate the molecular mechanisms underpinning these diseases and suggest potential drug targets.

Talin and vinculin are downregulated in atherosclerotic plaque; Tampere Vascular Study

BACKGROUND AND AIMS

Focal adhesions (FA) play an important role in the tissue remodeling and in the maintenance of tissue integrity and homeostasis. Talin and vinculin proteins are among the major constituents of FAs contributing to cellular well-being and intercellular communication.

METHODS

Microarray analysis (MA) and qRT-PCR low-density array were implemented to analyze talin-1, talin-2, meta-vinculin and vinculin gene expression in circulating blood and arterial plaque.

RESULTS

All analyzed genes were significantly and consistently downregulated in plaques (carotid, abdominal aortic and femoral regions) compared to left internal thoracic artery (LITA) control. The use of LITA samples as controls for arterial plaque samples was validated using immunohistochemistry by comparing LITA samples with healthy arterial samples from a cadaver. Even though the differences in expression levels between stable and unstable plaques were not statistically significant, we observed further negative tendency in the expression in unstable atherosclerotic plaques. The confocal tissue imaging revealed gradient of talin-1 expression in plaque with reduction close to the vessel lumen. Similar gradient was observed for talin-2 expression in LITA controls but was not detected in plaques. This suggests that impaired tissue mechanostability affects the tissue remodeling and healing capabilities leading to development of unstable plaques.

CONCLUSIONS

The central role of talin and vinculin in cell adhesions suggests that the disintegration of the tissue in atherosclerosis could be partially driven by downregulation of these genes, leading to loosening of cell-ECM interactions and remodeling of the tissue.

A two-phase procedure for non-normal quantitative trait genetic association study

BACKGROUND

The nonparametric trend test (NPT) is well suitable for identifying the genetic variants associated with quantitative traits when the trait values do not satisfy the normal distribution assumption. If the genetic model, defined according to the mode of inheritance, is known, the NPT derived under the given genetic model is optimal. However, in practice, the genetic model is often unknown beforehand. The NPT derived from an uncorrected model might result in loss of power. When the underlying genetic model is unknown, a robust test is preferred to maintain satisfactory power.

RESULTS

We propose a two-phase procedure to handle the uncertainty of the genetic model for non-normal quantitative trait genetic association study. First, a model selection procedure is employed to help choose the genetic model. Then the optimal test derived under the selected model is constructed to test for possible association. To control the type I error rate, we derive the joint distribution of the test statistics developed in the two phases and obtain the proper size.

CONCLUSIONS

The proposed method is more robust than existing methods through the simulation results and application to gene DNAH9 from the Genetic Analysis Workshop 16 for associated with Anti-cyclic citrullinated peptide antibody further demonstrate its performance.