Characterization of single chain urokinase-type plasminogen activator with a novel amino-acid substitution in the kringle structure

Gene Association Study of the Urokinase Plasminogen Activator and Its Receptor Gene in Alzheimer's Disease

Background

The role of the innate immune system has long been associated with Alzheimer's disease (AD). There is now accumulating evidence that the soluble Urokinase Plasminogen Activator Receptor pathway, and its genes, PLAU and PLAUR may be important in AD, and yet there have been few genetic association studies to explore this.

Objective

This study utilizes the DNA bank of the Brains for Dementia Research cohort to investigate the genetic association of common polymorphisms across the PLAU and PLAUR genes with AD.

Methods

TaqMan genotyping assays were used with standard procedures followed by association analysis in PLINK.

Results

No association was observed between the PLAU gene and AD; however, two SNPs located in the PLAUR gene were indicative of a trend towards association but did not surpass multiple testing significance thresholds.

Conclusions

Further genotyping studies and exploration of the consequences of these SNPs on gene expression and alternative splicing are warranted to fully uncover the role this system may have in AD.

Tale of two systems: the intertwining duality of fibrinolysis and lipoprotein metabolism

Fibrinolysis is an enzymatic process that breaks down fibrin clots, while dyslipidemia refers to abnormal levels of lipids and lipoproteins in the blood. Both fibrinolysis and lipoprotein metabolism are critical mechanisms that regulate a myriad of functions in the body, and the imbalance of these mechanisms is linked to the development of pathologic conditions, such as thrombotic complications in atherosclerotic cardiovascular diseases. Accumulated evidence indicates the close relationship between the 2 seemingly distinct and complicated systems-fibrinolysis and lipoprotein metabolism. Observational studies in humans found that dyslipidemia, characterized by increased blood apoB-lipoprotein and decreased high-density lipoprotein, is associated with lower fibrinolytic potential. Genetic variants of some fibrinolytic regulators are associated with blood lipid levels, supporting a causal relationship between these regulators and lipoprotein metabolism. Mechanistic studies have elucidated many pathways that link the fibrinolytic system and lipoprotein metabolism. Moreover, profibrinolytic therapies improve lipid panels toward an overall cardiometabolic healthier phenotype, while some lipid-lowering treatments increase fibrinolytic potential. The complex relationship between lipoprotein and fibrinolysis warrants further research to improve our understanding of the bidirectional regulation between the mediators of fibrinolysis and lipoprotein metabolism.

Searching for Genetic Biomarkers for Hereditary Angioedema Due to C1-Inhibitor Deficiency (C1-INH-HAE)

Existing evidence indicates that modifier genes could change the phenotypic outcome of the causal SERPING1 variant and thus explain the expression variability of hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE). To further examine this hypothesis, we investigated the presence or absence of 18 functional variants of genes encoding proteins involved in the metabolism and function of bradykinin, the main mediator of C1-INH-HAE attacks, in relation to three distinct phenotypic traits of patients with C1-INH-HAE, i.e., the age at disease onset, the need for long-term prophylaxis (LTP), and the severity of the disease. Genetic analyses were performed by a validated next-generation sequencing platform. In total, 233 patients with C1-INH-HAE from 144 unrelated families from five European countries were enrolled in the study. Already described correlations between five common functional variants [F12-rs1801020, KLKB1-rs3733402, CPN1-rs61751507, and two in SERPING1 (rs4926 and rs28362944)] and C1-INH-HAE severity were confirmed. Furthermore, significant correlations were found between either the age at disease onset, the LTP, or the severity score of the disease and a series of other functional variants (F13B-rs6003, PLAU-rs2227564, SERPINA1-rs28929474, SERPINA1-rs17580, KLK1-rs5515, SERPINE1-rs6092, and F2-rs1799963). Interestingly, correlations uncovered in the entire cohort of patients were different from those discovered in the cohort of patients carrying missense causal SERPING1 variants. Our findings indicate that variants other than the SERPING1 causal variants act as independent modifiers of C1-INH-HAE severity and could be tested as possible prognostic biomarkers.

Two Rare Variants in PLAU and BACE1 Genes-Do They Contribute to Semantic Dementia Clinical Phenotype?

We have performed whole-genome sequencing to identify the genetic variants potentially contributing to the early-onset semantic dementia phenotype in a patient with family history of dementia and episodic memory deficit accompanied with profound semantic loss. Only very rare variants of unknown significance (VUS) have been identified: a nonsense variant c.366C>A/p.Cys122* in plasminogen activator, urokinase (PLAU) and a missense variant c.944C>T/p.Thr315Met in β-site APP-cleaving enzyme 1 (BACE1)-along with known disease-modifying variants of moderate penetrance. Patient-derived fibroblasts showed reduced PLAU and elevated BACE1 mRNA and protein levels compared to control fibroblasts. Successful rescue of PLAU mRNA levels by nonsense-mediated mRNA decay (NMD) inhibitor (puromycin) confirmed NMD as the underlying mechanism. This is the first report of the PLAU variant with the confirmed haploinsufficiency, associated with semantic dementia phenotype. Our results suggest that rare variants in the PLAU and BACE1 genes should be considered in future studies on early-onset dementias.

Associations between SNPS in the genes encoding urokinase system proteins and the risk of placental insufficiency

Placental insufficiency (PI) and its complications are multifactorial conditions that cause perinatal morbidity and mortality. Since the urokinase system is involved in placentation, it should have a role in PI pathogenesis. The aim of this work was to study the associations between single nucleotide polymorphisms (SNPs) of genes coding for protein components of the urokinase system and PI, as well as investigate their effect on the expression of these proteins in the placenta and placental structure. We examined 114 women with uncomplicated pregnancy and delivery, 48 female patients with pre-eclampsia and/or intrauterine growth restriction (IUGR), and 95 newborns, (pre-eclampsia and/or IUGR: n = 60; uncomplicated pregnancy and delivery: n = 35). Maternal and fetal DNAs were genotyped using real-time PCR. Placenta fragments were subjected to morphometry and immunohistochemistry. We discovered the associations between PI and the maternal C allele of rs4065 (PI group: СС-СТ 64.1%, TT 35.9%; controls: СС-СТ 25.6%, TT 74.49%; OR (95%CI): 6.83 (2.63–17.79)), the maternal A allele of rs2302524 (GG-GA 20.5%, AA 79.5% vs. GG-GA 48.1%, AA 51.9%, OR (95%CI): 0.27 (0.1–0.71)), the fetal C allele of rs4065 (СС-СТ 76.4 %, TT 23.6% vs. СС-СТ 69.6%, TT 30.4%, OR (95%CI): 1.37 (0.45–4.17)), and the fetal C allele of rs344781 (TT-TC 69.1%, СС 30.9% vs. TT-TC 95.7%, СС 4.3%, OR (95% CI): 5.02 (1.07–23.6)). The multivariate analysis confirmed the significance of the fetal rs4065 genotype. In patients with PI, uPA expression was lower (ME (95%CI): 116.45 (100.5; 128.74) vs. 126.09 (113.76; 139.19); р < 0.05). No associations were established between SNPs and protein expression. The degree of vascularization depended on the maternal rs4065 genotype (the stroma-to-vessel ratio for the CC genotype was 0.17 (0.15; 0.19); for the CT genotype, 0.18 (0.15; 0.21) and for the TT genotype, 0.23 (0.2; 0.27); p < 0.05). We conclude that high placental uPA and the presence of the fetal TT rs4065 genotype are protective against the risk of PI.

Association between the polymorphisms of urokinase plasminogen activation system and cancer risk: a meta-analysis

Purpose

The present study aimed to investigate the potential association between the urokinase plasminogen activation (uPA) system polymorphisms (rs4065, rs2227564, and rs344781) and cancer risk.

Methods

An extensive search was performed to identify published case–control studies on the association between the uPA system polymorphisms and cancer risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the relationship between the uPA system polymorphisms and cancer risk.

Results

A total of 20 studies comprising 7,037 cancer cases and 10,094 controls were identified and included in the present meta-analysis. Overall, significantly increased cancer risk was associated with the uPA polymorphism rs4065 (T vs C: OR 1.50, 95% CI: 1.19–1.89; TT vs CC: OR 4.63, 95% CI: 3.10–6.91; dominant model: OR 1.93, 95% CI: 1.60–2.33; recessive model: OR 3.02, 95% CI: 1.26–7.25) and the uPA receptor polymorphism rs344781 (T vs C: OR 1.13, 95% CI: 1.04–1.23; TC vs CC: OR 1.26, 95% CI: 1.06–1.49; TT vs CC: OR 1.35, 95% CI: 1.13–1.63; dominant model: OR 1.29, 95% CI: 1.10–1.52). No significant association was found between the uPA polymorphism rs2227564 and cancer risk. Subgroup analysis suggests that the T allele of the rs4065 (T allele vs C allele: OR 1.50, 95% CI: 1.19–1.89) and rs344781 polymorphisms (T allele vs C allele: OR 1.13, 95% CI: 1.04–1.23) was associated with increased cancer risk in Asians.

Conclusion

Our results suggest that the uPA polymorphism rs4065 and the uPA receptor polymorphism rs344781 are associated with increased cancer risk.

The PLAU P141L single nucleotide polymorphism is associated with collateral circulation in patients with coronary artery disease

INTRODUCTION AND OBJECTIVES

Urokinase-type plasminogen activator, which is encoded by the PLAU gene, plays a prominent role during collateral arterial growth. We investigated whether the PLAU P141L (C > T) polymorphism, which causes a mutation in the kringle domain of the protein, is associated with coronary collateral circulation in a cohort of 676 patients with coronary artery disease.

METHODS

The polymorphism was genotyped in blood samples using a TaqMan-based genotyping assay, and collateral circulation was assessed by the Rentrop method. Multivariate logistic regression models adjusted by clinically relevant variables to estimate odds ratios were used to examine associations of PLAU P141L allelic variants and genotypes with collateral circulation.

RESULTS

Patients with poor collateral circulation (Rentrop 0-1; n = 547) showed a higher frequency of the TT genotype than those with good collateral circulation (Rentrop 2-3; n = 129; P = .020). The T allele variant was also more common in patients with poor collateral circulation (P = .006). The odds ratio of having poorly developed collaterals in patients bearing the T allele (adjusted for clinically relevant variables) was statistically significant under the dominant model (odds ratio = 1.83 [95% confidence interval, 1.16-2.90]; P = .010) and the additive model (odds ratio = 1.73 [95% confidence interval, 1.14-2.62]; P = .009).

CONCLUSIONS

An association was found between coronary collateral circulation and the PLAU P141L polymorphism. Patients with the 141L variant are at greater risk of developing poor coronary collateral circulation.

The study of t-PA, u-PA and PAI-1 genes polymorphisms in patients with abdominal aortic aneurysm

The most important feature of abdominal aortic aneurysm (AAA) pathogenesis is an enzymatic degradation of elastic lamellae and extracellular matrix proteins particularly with participation of matrix metalloproteinases. Plasmin, which is responsible for the dissolution of fibrin in blood vessels, plays also a key role in the cascade for activation of the metalloproteinases. The purpose of this study was to evaluate the influence of selected polymorphisms in genes coding for tissue plasminogen activator (−7351 C/T polymorphism), urokinase-type plasminogen activator (1788 C/T polymorphism) and plasminogen activator inhibitor 1 (−675 4G/5G and −844 G/A polymorphism) on the susceptibility to AAA. We performed a case–control study of 153 polish patients hospitalized due to AAA and compared them with matched healthy control subjects. The polymorphisms were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments or through high-resolution melting analysis. In this study we have found lower frequency of wild-type GG genotype of the −844G/A PAI-1 polymorphism in cases than in controls, what may suggest the protective effect of this genotype for the risk of AAA development. None of the remaining polymorphisms tested were associated with AAA occurrence.

Meta-analysis of the association between urokinase-plasminogen activator gene rs2227564 polymorphism and Alzheimer's disease

OBJECTIVE

The association between urokinase-plasminogen activator (PLAU) gene rs2227564 polymorphism and Alzheimer's disease (AD) risk has been widely reported across different ethnic populations, with inconsistent results. Thus, we performed a meta-analysis to assess the association between PLAU rs2227564 polymorphism and AD risk.

METHODS

Fixed or random effect model was used as the pooling method to assess the basis of homogeneity test among studies. Summarized estimation of odds ratio (OR) and 95% confidence interval (CI) were calculated. Heterogeneity among studies was evaluated using Q test and I (2). Publication bias was estimated using Harbord's test.

RESULTS

A total of 27 studies (comprising 6100 AD cases and 5718 controls) were included in this meta-analysis. The present meta-analysis showed a significant increased effect of T allele on risk of AD in dominant model (fixed effect model [FEM] OR 1.123, 95% CI 1.025-1.231) and heterozygote comparison (CT vs CC; FEM OR 1.126, 95% CI 1.027-1.235). No publication bias was detected.

CONCLUSION

This meta-analysis showed that T allele of rs2227564 polymorphism in PLAU gene could increase the effects on risk of AD, and this result needs to be confirmed by further studies.

Association of calcium urolithiasis with urokinase P141L and 3'-UTR C>T polymorphisms in a Japanese population

This was a case-control study to analyze the associations between calcium urolithiasis and the urokinase polymorphisms, P141L (rs2227564) and 3'-UTR C>T (rs4065), in a Japanese population. Cases consisted of 232 patients with urinary calcium stones (174 men and 58 women) who presented to a general hospital between April 2009 and June 2011. Among these cases, 115 (49.6 %) patients had calcium oxalate stones alone, and 113 (48.7 %) patients had calcium oxalate stones mixed with calcium phosphate stones. Controls consisted of 454 subjects who had a routine health check-up in the same prefecture. The two polymorphisms were genotyped via polymerase chain reaction with confronting two-pair primers. In the control group, the genotype frequencies of P141L were 0.573 for PP, 0.375 for PL, and 0.052 for LL, and those of 3'-UTR C>T were 0.835 for CC, 0.165 for CT, and TT was not identified. Neither of the polymorphisms was significantly associated with urolithiasis. The age- and sex-adjusted odds ratios of urolithiasis were 0.96 [95 % confidence interval (CI), 0.66-1.41] for PL and 1.22 (0.58-2.57) for LL as compared with PP genotype of P141L, and 1.01 (0.62-1.64) for CT as compared with CC genotype of 3'-UTR C>T. When compared with the PP genotype of P141L, the frequency of PL was significantly lower in female cases with a family history of urolithiasis than in females without such family history (p = 0.028). P141L and 3'-UTR polymorphisms of the urokinase gene are not associated with urolithiasis in a Japanese population.

Genetic polymorphism of urokinase-type plasminogen activator is interacting with plasminogen activator inhibitor-1 to raise risk of cervical neoplasia

BACKGROUND AND OBJECTIVES

To evaluate the impact of plasminogen activator (PA) system genes, including urokinase plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1) gene polymorphisms in patients with the cervical neoplasia.

METHODS

In total, 336 blood samples were collected from healthy women and 136 patients with cervical neoplasia to analyze the gene polymorphisms of representative PA system genes.

RESULTS

There was no significant association between cervical neoplasia cases and gene polymorphisms of uPA, uPAR and PAI-1 genes as well as to the carcinogenesis of cervical if the cervical neoplasia cases were stratified to HSILs and invasive cancer cases. However, we found a mutual interaction between uPA/PAI-1 genes, which women carrying the uPA/PAI-1 CC/4G4G allele had a 1.70-fold higher risk (OR = 1.70; 95% CI 1.04-2.79) of cervical neoplasia compared with those carrying the CC/4G5G allele.

CONCLUSIONS

Individuals with uPA/PAI-1 CC/4G5G allele were in high susceptibility for cervical neoplasia. The combined polymorphism of uPA/PAI-1 might diminish the ability of PAI-1 to inhibiting cervical cancer carcinogenesis when PAI-1 alone as the role of inhibitor.

Association of putative functional variants in the PLAU gene and the PLAUR gene with myocardial infarction

uPA (urokinase-plasminogen activator) and its receptor (uPAR) have been implicated in a broad spectrum of pathophysiological processes, including fibrinolysis, proteolysis, inflammation, atherogenesis and plaque destabilization, all of which are involved in the pathogenesis of MI (myocardial infarction). We hypothesized that putative functional genetic variation in the two genes encoding uPA and uPAR (PLAU and PLAUR respectively) might influence the susceptibility to MI. We genotyped rs4065 [3'-UTR (untranslated region) *141C>T) and rs2227564 (Pro141Leu) in the PLAU gene as well as rs344781 (-516T>C) in the PLAUR gene in 633 MI patients and 1237 gender- and age-matched control subjects. Our results showed that the T allele of rs4065 was significantly associated with an increased risk of MI, with an adjusted OR (odds ratio) of 1.38 [95% CI (confidence interval), 1.07-1.78; P=0.012) under the dominant model, 1.4 (95% CI, 1.12-1.75; P=0.003) under the additive model and 2.5 (95% CI, 1.15-5.41; P=0.02) under the recessive model. The findings were then replicated in another independent case-control study including 545 MI patients and 597 control subjects. In conclusion, our results suggest that rs4065 might be a previously unknown genetic risk factor for MI in the Chinese Han population.

Common genetic variants associated with plasma fibrin D-dimer concentration in older European- and African-American adults

BACKGROUND AND OBJECTIVES

D-dimer is a hemostasis marker that reflects ongoing fibrin formation and degradation. There is significant inter-individual and inter-population variability in D-dimer concentration, but whether genetic factors underlie these differences is largely unknown. We hypothesized that common coagulation gene variants contribute to differences in circulating D-dimer concentration.

METHODS

The setting was European-American (EA; n = 1858) and African-American (AA; n = 327) unrelated older adults from the Cardiovascular Health Study (CHS), in which we genotyped SNPs in 42 genes related to blood coagulation and fibrinolysis.

RESULTS

Several fibrinogen gene polymorphisms, including the Thr312Ala Aalpha chain variant and the FGG-10034 C/T variant, were associated with approximately 20% higher plasma D-dimer levels in EA (false discovery rate < 5% for covariate-adjusted model). There was also some evidence that a Pro41Leu variant of the PLAU gene encoding urinary plasminogen activator and non-coding polymorphism of the plasminogen activator inhibitor type 1 gene (SERPINE1) were associated with higher plasma D-dimer in EA. There were no significant associations between the studied coagulation or fibrinolysis gene SNPs and plasma D-dimer levels in the smaller AA sample. However, each standard deviation increase in European ancestry assessed by ancestry-informative gene markers was associated with approximately 10% lower mean D-dimer levels in AA.

CONCLUSIONS

Together, common coagulation/fibrinolysis gene SNPs explained only approximately 2% of the variance in plasma D-dimer levels in EA. These findings suggest that the association of D-dimer with risk of vascular outcomes may be mediated largely by environmental factors, other genes, and/or genetic interactions.

Association of urokinase-type plasminogen activator with asthma and atopy

RATIONALE

Urokinase plasminogen activator (uPA) interacts with its receptor on inflammatory and migrating cells to regulate extracellular matrix degradation, cell adhesion, and inflammatory cell activation. It is necessary for the development of an appropriate immune response and is involved in tissue remodeling. The PLAU gene codes for this enzyme, and is located on 10q24. This region has demonstrated evidence for linkage in a genome scan for asthma in a sample from northeastern Quebec. Here, we hypothesized that uPA may function as a regulator of asthma susceptibility.

OBJECTIVES

To test for association between asthma and genetic variants of PLAU.

METHODS

We sequenced PLAU and tested for genetic association between identified variants and asthma-related traits in a French-Canadian familial collection (231 families, 1,139 subjects). Additional association studies were performed in two other family-based Canadian cohorts (Canadian Asthma Primary Prevention Study [CAPPS], 238 trios; and Study of Asthma Genes and the Environment [SAGE], 237 trios).

MEASUREMENTS AND MAIN RESULTS

In the original sample, under the dominant model, the common alleles, rs2227564C (P141) and rs2227566T, were associated with asthma (p = 0.011 and 0.045, respectively) and with airway hyperresponsiveness (AHR) (p = 0.026 and 0.038, respectively). Analysis of the linkage disequilibrium pattern also revealed association of the common haplotype for asthma, atopy, and AHR (p = 0.031, 0.043, and 0.006, respectively). Whereas no significant association was detected for PLAU single-nucleotide polymorphisms in the CAPPS cohort, association was observed in the SAGE cohort between the rs4065C allele and atopy under additive (p = 0.005) and dominant (p = 0.0001) genetic models.

CONCLUSIONS

This suggests a role for the uPA pathway in the pathogenesis of the disease.

Gene polymorphisms of fibrinolytic enzymes in coal workers' pneumoconiosis

The authors assessed the gene polymorphisms of missense C/T polymorphism in exon 6 of the urokinase-plasminogen activator (PLAU) gene (PLAU P141L), Alu-repeat in intron 8 of the tissue-type plasminogen activator (PLAT) gene (PLAT TPA25 Alu insertion), and 4G/5G in the promoter region of the serine proteinase inhibitor, clade E (SERPINE) or plasminogen activator inhibitor type 1 gene (SERPINE1 -675 4G/5G) in 153 healthy volunteers and 154 retired coal miners with coal miners' pneumoconiosis (CWP). The CWP subjects included 94 individuals with simple pneumoconiosis and 60 individuals with progressive massive fibrosis presenting with worse pulmonary function. The distributions of genotypes of these three genes did not differ between the control and CWP subjects or between subjects with simple pneumoconiosis and those with progressive massive fibrosis. However, by assessing duration of work and its interaction with genotypes by means of logistic regression, the authors found the missense C/T polymorphism in exon 6 of the PLAU gene to be an effect modifier of the association between work duration and the development of progressive massive fibrosis.

Preservation of the characteristics of the cultured human type II alveolar epithelial cells

The human type II alveolar epithelial cells lost their specific characteristics during cultivation. We examined the ultrastructural and biochemical nature of the human type II cells cultured by two culture systems. To make a physiological alveoli model, the epithelial cells were seeded onto the cell culture insert and allowed contact with the air directly. The cells exposed to the air expressed polarity and immature lamellar bodies in their cytoplasm. Separately, the alveolar epithelial cells were cultured as spheroids to construct the three-dimensional condition. These cells expressed mature morphological characteristics as epithelial cells and lamellar bodies. The expression of the surfactant apoprotein-A (SP-A) and -C (SP-C) mRNA was compared in the cells cultured as a monolayer, the air exposed and the spheroids. SP-A mRNA was detected in all the cultured epithelial cells, but SP-C mRNA, a specific protein for the type II cells, was expressed only in the cells forming spheroids. The expression of uPA, one of the fibrinolytic enzymes, its receptor (uPAR) and its inhibitor-1 (PAI-1) were also examined. The epithelial cells exposed to the air and formed spheroids expressed a larger amount of uPA mRNA than the monolayer, although the amount of uPAR mRNA were comparable in these cells. The amount of PAI-1 mRNA significantly increased when the epithelial cells were exposed to the air. These results indicate that the type II alveolar epithelial cells induced and preserved their specific characteristics by taking the physiological three-dimensional structure, and these characteristics were partially restored by exposure to the air. Those findings suggest that the alveolar epithelial cells should be cultivated in three-dimensional form with contact to the air to regenerate an appropriate alveolar tissue.

Elevated amyloid β protein (Aβ42) and late onset Alzheimer's disease are associated with single nucleotide polymorphisms in the urokinase-type plasminogen activator gene

Plasma amyloid beta protein (Abeta42) levels and late onset Alzheimer's disease (LOAD) have been linked to the same region on chromosome 10q. The PLAU gene within this region encodes urokinase-type plasminogen activator, which converts plasminogen to plasmin. Abeta aggregates induce PLAU expression thereby increasing plasmin, which degrades both aggregated and non-aggregated forms of Abeta. We evaluated single nucleotide polymorphisms (SNPs) in PLAU for association with Abeta42 and LOAD. PLAU SNP compound genotypes composed of haplotype pairs showed significant association with AD in three independent case-control series. PLAU SNP haplotypes associated significantly with plasma Abeta42 in 10 extended LOAD families. One of the SNPs analyzed was a missense C/T polymorphism in exon 6 of PLAU (PLAU_1=rs2227564), which causes a proline to leucine change (P141L). We analyzed PLAU_1 for association with AD in six case-control series and 24 extended LOAD families. The CT and TT PLAU_1 genotypes showed association (P=0.05) with an overall estimated odds ratio of 1.2 (1.0-1.5). The CT and TT genotypes of PLAU_1 were also associated with significant age-dependent elevation of plasma Abeta42 in 24 extended LOAD families (P=0.0006). In knockout mice lacking the PLAU gene, plasma--but not brain--Abeta42 as well as Abeta40 was significantly elevated, also in an age-dependent manner. The PLAU_1 associations were independent of the associations we found among plasma Abeta42, LOAD and variants in the IDE or VR22 region. These results provide strong evidence that PLAU or a nearby gene is involved in the development of LOAD. PLAU_1 is a plausible pathogenic mutation that could act by increasing Abeta42, but additional biological experiments are required to show this definitively.

Single-nucleotide polymorphism of the urokinase-plasminogen activator gene during aging and transformation of human diploid kidney cell cultures

Single-nucleotide polymorphisms (SNPs) are differences in the nucleotide sequence of a specific gene from different individuals. The frequency at which SNPs occur varies among individuals, is gene dependent, and may be influenced by the aging process or by mechanisms that result in cell transformation. Urokinase-plasminogen activator (uPA) is a serine protease that is important in embryonic development, aging, and the onset of pathogenic conditions. The frequency of SNP and the stability of the SNPs in the uPA gene have not been defined with regard to processes that are associated with cellular aging or transformation. In this study, the complete nucleotide sequence has been determined for the gene encoding uPA from 26 human diploid kidney cell lines. The frequency of SNP occurrence within the uPA gene and whether this frequency changed during cellular aging, or after cell transformation, were determined. The results demonstrated three donor-dependent SNPs. One SNP was located at base pair 422, which is in the region of the gene responsible for encoding the high-molecular weight domain of uPA (HMW-uPA). The other SNPs were located at base pairs 691 and 822, both of which are in the region of the gene responsible for encoding the low-molecular weight domain of uPA (LMW-uPA). Single-nucleotide polymorphisms were not detected in the portion of the gene responsible for encoding the uPA secretion signal. Leucine or proline would be encoded at amino acid 141 of HMW-uPA as the result of an SNP at base pair 422. The SNP detected at base pair 691 would encode for lysine or glutamine at amino acid 231 of LMW-uPA. The SNP detected at base pair 822 would not change the encoded asparagine located at position 274 of the protein. The SNPs identified in this study were donor dependent and were not altered during cellular aging, or by changes in karyology due to spontaneous transformation of the cell line. These results demonstrate that the integrity of the uPA gene is stable and not subject to alterations that accompany cell aging or transformation.

Variation in the urokinase-plasminogen activator gene does not explain the chromosome 10 linkage signal for late onset AD

Linkage studies indicate that the same region of chromosome 10 contains a risk locus for late onset Alzheimer disease (LOAD) and a QTL for plasma Abeta42 levels suggesting that a single locus may influence risk for AD by elevating plasma Abeta42 [Ertekin-Taner et al., 2000; Myers et al., 2000]. A strong positional and biological candidate is the urokinase-plasminogen activator (PLAU) gene. Eight polymorphisms spanning the entire gene were examined using case control (CC) and family-based association methods. No association was observed by any method making it unlikely that variation in PLAU explains our linkage data.

Antigen levels of the urokinase-type plasminogen activator and its gene polymorphisms in colorectal cancer

We analysed the distribution of genotypes of two polymorphisms in the urokinase-type plasminogen activator (uPA) gene: C-->T substitution in exon 6 and T-->C substitution in intron 7 in 52 subjects with colorectal cancer. Genotypes were determined in tumour tissue and distant mucosa samples by allele-specific polymerase chain reaction. The antigen levels of uPA in cancer tissue were higher than in distant mucosa as measured by enzyme-linked immunosorbent assay. The level of uPA antigens in cancer samples with the C/C genotype of C-->T polymorphism in exon 6 was higher than in samples with C/T and T/T genotypes. No differences in the level of uPA antigens between the alleles of the intron 7 T-->C polymorphism were found. As uPA can be involved in cancer invasion and metastasis, C/C genotype in exon 6 of uPA gene can be further considered as being related to colorectal cancer progression.

Increased secretion of urokinase-type plasminogen activator by human lung microvascular endothelial cells

Human lung microvascular endothelial cells (HLMECs) secreted 1.5-15 times more urokinase-type plasminogen activator (uPA) antigen than human hepatic microvascular endothelial cells, human umbilical vein endothelial cells (HUVECs), angioma endothelial cells, and lung fibroblasts. All of these cells also secreted a 100-fold greater amount of plasminogen activator inhibitor-1 than of uPA antigen, and uPA activities were not detected in the culture medium. The expression of uPA mRNA in HLMECs was higher (100-fold) compared with HUVECs, angioma endothelial cells, and lung fibroblasts. HLMECs secreted uPA antigen on both the luminal and basal sides of the cells. On the other hand, HLMECs secreted a 10- to 15-fold lower amount of tissue-type plasminogen activator than HUVECs, mostly on the luminal side. After stimulation with interleukin (IL)-1beta, HLMECs secreted a six- to ninefold amount of uPA antigen. In contrast, no stimulatory effect was observed in HUVECs even under high IL-1beta concentrations. The secretion of uPA and plasminogen activator inhibitor-1 from HLMECs was also enhanced by tumor necrosis factor-alpha and IL-2. These results suggest that HLMECs may contribute not only to the patency of lung vessels but also to the maintenance of alveolar functions through the production and secretion of uPA, especially in the presence of inflammatory cytokines.