Identification of the substrates for plasma hyaluronan binding protein

Hyaluronic Acid Interacting Molecules Mediated Crosstalk between Cancer Cells and Microenvironment from Primary Tumour to Distant Metastasis

Hyaluronic acid (HA) is a prominent component of the extracellular matrix, and its interactions with HA-interacting molecules (HAIMs) play a critical role in cancer development and disease progression. This review explores the multifaceted role of HAIMs in the context of cancer, focusing on their influence on disease progression by dissecting relevant cellular and molecular mechanisms in tumour cells and the tumour microenvironment. Cancer progression can be profoundly affected by the interactions between HA and HAIMs. They modulate critical processes such as cell adhesion, migration, invasion, and proliferation. The TME serves as a dynamic platform in which HAIMs contribute to the formation of a unique niche. The resulting changes in HA composition profoundly influence the biophysical properties of the TME. These modifications in the TME, in conjunction with HAIMs, impact angiogenesis, immune cell recruitment, and immune evasion. Therefore, understanding the intricate interplay between HAIMs and HA within the cancer context is essential for developing novel therapeutic strategies. Targeting these interactions offers promising avenues for cancer treatment, as they hold the potential to disrupt critical aspects of disease progression and the TME. Further research in this field is imperative for advancing our knowledge and the treatment of cancer.

Elucidating the role of intrinsic adenosine A1 receptors in acute alcoholism using human-induced pluripotent stem cell-derived hepatocytes

Acute alcoholic hepatitis (AAH) from binge drinking is a serious disease. It is associated with a high mortality rate, especially among young adults. Apoptosis is known to be a primary cause of liver damage, and it can be induced by either intrinsic signaling pathways or by reactive oxygen species (ROS). Adenosine A1 receptors (ADORA1) are known to be involved in ethanol metabolism; however, underlying mechanism is not well understood. For investigating how the intrinsic ADORA1 function in ethanol metabolism in normal human hepatocytes without interference by extrinsic molecules, primary hepatocytes pose a challenge, due to unavoidable contamination by other kinds of cells in the liver. Also, they are difficult to culture stably. As a novel alternative, hepatocytes derived from human-induced pluripotent stem cells were employed because they display similar function to primary hepatocytes and they can be stably cultured. The dynamics and integrity of signal transduction mechanisms were investigated by following chronological changes in gene expression. This shed light on how and when the ADORA1 function and on causal relationships between the pathways and clinical symptoms. The findings of the present study shows that ADORA1 are most activated soon after exposure to ethanol, and transfection of small interfering RNA targeting ADORA1-messenger-RNA (ADORA1-siRNA) into the hepatocytes significantly suppresses production of actin protein and ROS. It suggests that ADORA1 in the liver contribute to apoptosis in acute alcoholism through both intrinsic pathway and ROS activity. Also, actin that is abundant in the cells could be an appropriate biomarker evaluating hepatic function status.

The Impact of Acute Nutritional Interventions on the Plasma Proteome

CONTEXT

Humans respond profoundly to changes in diet, while nutrition and environment have a great impact on population health. It is therefore important to deeply characterize the human nutritional responses.

OBJECTIVE

Endocrine parameters and the metabolome of human plasma are rapidly responding to acute nutritional interventions such as caloric restriction or a glucose challenge. It is less well understood whether the plasma proteome would be equally dynamic, and whether it could be a source of corresponding biomarkers.

METHODS

We used high-throughput mass spectrometry to determine changes in the plasma proteome of i) 10 healthy, young, male individuals in response to 2 days of acute caloric restriction followed by refeeding; ii) 200 individuals of the Ely epidemiological study before and after a glucose tolerance test at 4 time points (0, 30, 60, 120 minutes); and iii) 200 random individuals from the Generation Scotland study. We compared the proteomic changes detected with metabolome data and endocrine parameters.

RESULTS

Both caloric restriction and the glucose challenge substantially impacted the plasma proteome. Proteins responded across individuals or in an individual-specific manner. We identified nutrient-responsive plasma proteins that correlate with changes in the metabolome, as well as with endocrine parameters. In particular, our study highlights the role of apolipoprotein C1 (APOC1), a small, understudied apolipoprotein that was affected by caloric restriction and dominated the response to glucose consumption and differed in abundance between individuals with and without type 2 diabetes.

CONCLUSION

Our study identifies APOC1 as a dominant nutritional responder in humans and highlights the interdependency of acute nutritional response proteins and the endocrine system.

Factor VII Activating Protease (FSAP) and Its Importance in Hemostasis—Part I: FSAP Structure, Synthesis and Activity Regulation: A Narrative Review

Factor VII activating protease (FSAP) was first isolated from human plasma less than 30 years ago. Since then, many research groups have described the biological properties of this protease and its role in hemostasis and other processes in humans and other animals. With the progress of knowledge about the structure of FSAP, several of its relationships with other proteins or chemical compounds that may modulate its activity have been explained. These mutual axes are described in the present narrative review. The first part of our series of manuscripts on FSAP describes the structure of this protein and the processes leading to the enhancement and inhibition of its activities. The following parts, II and III, concern the role of FSAP in hemostasis and in the pathophysiology of human diseases, with particular emphasis on cardiovascular diseases.

Familial non medullary thyroid carcinoma: Beyond the syndromic forms

Familial non-medullary thyroid cancer is defined as the presence of non-medullary thyroid cancer in two or more first-degree relatives, in the absence of other predisposing factors. It represents up to 9% of differentiated thyroid cancers, and only a minority appears in well-known hereditary syndromes that associate thyroid cancer among many other clinical manifestations. However, in more than 95% of cases, thyroid cancer appears isolated, and its genetic causes have yet to be elucidated. We review here the current knowledge of the genetic basis of this pathology, as well as its clinical characteristics. Understanding the genetic mechanisms implied would help to comprehend the metabolic pathways involved, with the consequent potential therapeutic application. In addition, it would allow genetic counseling and to focus our efforts on patients at risk of developing this disorder.

Familial non medullary thyroid carcinoma: Beyond the syndromic forms

Familial non-medullary thyroid cancer is defined as the presence of non-medullary thyroid cancer in two or more first-degree relatives, in the absence of other predisposing factors. It represents up to 9% of differentiated thyroid cancers, and only a minority appears in well-known hereditary syndromes that associate thyroid cancer among many other clinical manifestations. However, in more than 95% of cases, thyroid cancer appears isolated, and its genetic causes have yet to be elucidated. We review here the current knowledge of the genetic basis of this pathology, as well as its clinical characteristics. Understanding the genetic mechanisms implied would help to comprehend the metabolic pathways involved, with the consequent potential therapeutic application. In addition, it would allow genetic counseling and to focus our efforts on patients at risk of developing this disorder.

Familial non-medullary thyroid carcinoma: clinico-pathological features, current knowledge and novelty regarding genetic risk factors

Familial non-medullary thyroid cancer (FNMTC) constitutes 3-9% of all thyroid cancers and occurs in two or more first-degree relatives in the absence of predisposing environmental factors. Out of all FNMTC cases, only 5% are represented by syndromic forms (Gardner's Syndrome, familial adenomatous polyposis, Cowden's Syndrome, Carney complex 1, Werner's Syndrome and DICER1 syndrome), in which thyroid cancer occurs as a minor component and the genetic alterations are well-known. The non-syndromic forms represent the majority of all FNMTCs (95%), and the thyroid cancer is the predominant feature. Several low penetration susceptibility risk loci or genes (i.e. TTF1, FOXE1, SRGAP1, SRRM2, HABP2, MAP2K5, and DUOX2), here fully reviewed, have been proposed in recent years with a possible causative role, though the results are still not conclusive or reliable. FNMTC is indistinguishable from sporadic non-medullary thyroid cancer (sNMTC), which means that FNMTC cannot be diagnosed until at least one of the patient's first-degree relatives is affected by tumor. Some studies reported that the non-syndromic FNMTC is more aggressive than the sNMTC, being characterized by a younger age of onset and a higher rate of multifocal and bilateral tumors, extrathyroidal extension, lymph node metastasis, and recurrence. On the contrary, other studies did not find clinical differences between non-syndromic FNMTCs and sporadic cases. Here, I reported an extensive review on genetic and clinico-pathological features of the FNMTC, with particular attention on novel genetic risk factors for non-syndromic forms.

Association between FSAP 1601GA polymorphism and venous thromboembolism risk: A meta-analysis

OBJECTIVE

Previous several studies have shown that factor VII-activating protease (FSAP) gene 1601G>A polymorphism is related to the occurrence of venous thromboembolism, but the results are inconsistent and controversial. Therefore, we conducted a meta-analysis to explore the association between FSAP 1601G>A polymorphism and venous thromboembolism susceptibility.

METHODS

We managed a systematic literature search through Pubmed, Embase, Web of Science, China National Knowledge Infrastructure, and WanFang databases to collect research data related to FSAP gene 1601G>A polymorphism and susceptibility to venous thromboembolism published before May 2019. Data analysis was performed through Revman 5.3 and Stata 12.0 software, the pooled odd ratios and 95% confidence intervals were calculated. Additionally, the sensitivity analysis and publication bias assessment were also performed.

RESULTS

A total of seven case-control studies were included and evaluated, including 2411 venous thromboembolism cases and 2850 controls. The meta-analysis results revealed that the FSAP 1601G>A mutation is associated with venous thromboembolism risk, and statistically significance was observed under three genetic comparison models (A: G, odds ratio: 1.33, 95% confidence interval: 1.07-1.66; GA: GG, odds ratio: 1.34, 95% confidence interval: 1.06-1.68; and GA + AA: GG, odds ratio: 1.33, 95% confidence interval: 1.06-1.66).

CONCLUSION

This study demonstrated that the FSAP 1601G>A polymorphism may be associated with venous thromboembolism susceptibility.

Altered structure and function of fibrinogen after cleavage by Factor VII Activating Protease (FSAP)

Factor VII Activating Protease (FSAP) is a plasma protease affecting both coagulation and fibrinolysis. Although a role in hemostasis is still unclear, the identification of additional physiologic substrates will help to elucidate its role in this context. FSAP has been reported to cleave fibrinogen, but the functional consequences of this are not known. We have therefore undertaken this study to determine the implications of this cleavage for fibrin-clot formation and its lysis. Treatment of human fibrinogen with FSAP released an N-terminal peptide from the Bβ chain (Bβ1-53) and subsequently the fibrinopeptide B; within the Aα chain a partial truncation of the αC-region by multiple cleavages was seen. The truncated fibrinogen showed a delayed thrombin-catalyzed polymerization and formed fibrin clots of reduced turbidity, indicative of thinner fibrin fibers. Confocal laser scanning and scanning electron microscopy of these clots revealed a less coarse fibrin network with thinner fibers and a smaller pore size. A lower pore size was also seen in permeability studies. Unexpectedly, FSAP-treated fibrinogen or plasma exhibited a significantly faster tPA-driven lysis, which correlated exclusively with cleavage of fibrinogen and not with activation of plasminogen activators. Similar observations were also made in plasma after activation of endogenous zymogen FSAP, but not in plasma of carrier of the rare Marburg I single nucleotide polymorphism. In conclusion, altering fibrin clot properties by fibrinogenolysis is a novel function of FSAP in the vasculature, which facilitates clot lysis and may in vivo contribute to reduced fibrin deposition during thrombosis.

Application of multiplexed ion mobility spectrometry towards the identification of host protein signatures of treatment effect in pulmonary tuberculosis

Rationale:

The monitoring of TB treatments in clinical practice and clinical trials relies on traditional sputum-based culture status indicators at specific time points. Accurate, predictive, blood-based protein markers would provide a simpler and more informative view of patient health and response to treatment.

Objective:

We utilized sensitive, high throughput multiplexed ion mobility-mass spectrometry (IM-MS) to characterize the serum proteome of TB patients at the start of and at 8 weeks of rifamycin-based treatment. We sought to identify treatment specific signatures within patients as well as correlate the proteome signatures to various clinical markers of treatment efficacy.

Methods:

Serum samples were collected from 289 subjects enrolled in CDC TB Trials Consortium Study 29 at time of enrollment and at the end of the intensive phase (after 40 doses of TB treatment). Serum proteins were immunoaffinity-depleted of high abundant components, digested to peptides and analyzed for data acquisition utilizing a unique liquid chromatography IM-MS platform (LC-IM-MS). Linear mixed models were utilized to identify serum protein changes in the host response to antibiotic treatment as well as correlations with culture status end points.

Results:

A total of 10,137 peptides corresponding to 872 proteins were identified, quantified, and used for statistical analysis across the longitudinal patient cohort. In response to TB treatment, 244 proteins were significantly altered. Pathway/network comparisons helped visualize the interconnected proteins, identifying up regulated (lipid transport, coagulation cascade, endopeptidase activity) and down regulated (acute phase) processes and pathways in addition to other cross regulated networks (inflammation, cell adhesion, extracellular matrix). Detection of possible lung injury serum proteins such as HPSE, significantly downregulated upon treatment. Analyses of microbiologic data over time identified a core set of serum proteins (TTHY, AFAM, CRP, RET4, SAA1, PGRP2) which change in response to treatment and also strongly correlate with culture status. A similar set of proteins at baseline were found to be predictive of week 6 and 8 culture status.

Conclusion:

A comprehensive host serum protein dataset reflective of TB treatment effect is defined. A repeating set of serum proteins (TTHY, AFAM, CRP, RET4, SAA1, PGRP2, among others) were found to change significantly in response to treatment, to strongly correlate with culture status, and at baseline to be predictive of future culture conversion. If validated in cohorts with long term follow-up to capture failure and relapse of TB, these protein markers could be developed for monitoring of treatment in clinical trials and in patient care.

Analysis of the substrate specificity of Factor VII activating protease (FSAP) and design of specific and sensitive peptide substrates

Factor VII (FVII) activating protease (FSAP) is a circulating serine protease that is likely to be involved in a number of disease conditions such as stroke, atherosclerosis, liver fibrosis, thrombosis and cancer. To date, no systematic information is available about the substrate specificity of FSAP. Applying phage display and positional scanning substrate combinatorial library (PS-SCL) approaches we have characterised the specificity of FSAP towards small peptides. Results were evaluated in the context of known protein substrates as well as molecular modelling of the peptides in the active site of FSAP. The representative FSAP-cleaved sequence obtained from the phage display method was Val-Leu-Lys-Arg-Ser (P4-P1'). The sequence X-Lys/Arg-Nle-Lys/Arg (P4-P1) was derived from the PS-SCL method. These results show a predilection for cleavage at a cluster of basic amino acids on the nonprime side. Quenched fluorescent substrate (Ala-Lys-Nle-Arg-AMC) (amino methyl coumarin) and (Ala-Leu-Lys-Arg-AMC) had a higher selectivity for FSAP compared to other proteases from the hemostasis system. These substrates could be used to measure FSAP activity in a complex biological system such as plasma. In histone-treated plasma there was a specific activation of pro-FSAP as validated by the use of an FSAP inhibitory antibody, corn trypsin inhibitor to inhibit Factor XIIa and hirudin to inhibit thrombin, which may account for some of the haemostasis-related effects of histones. These results will aid the development of further selective FSAP activity probes as well as specific inhibitors that will help to increase the understanding of the functions of FSAP in vivo.

Role of glycine 221 in catalytic activity of hyaluronan-binding protein 2

HABP2 (hyaluronan-binding protein 2) is a Ca²⁺-dependent serine protease with putative roles in blood coagulation and fibrinolysis. A G221E substitution, known as the Marburg I polymorphism, reportedly affects HABP2 function and has been associated with increased risk for cardiovascular disease. However, the importance of Gly-221 for HABP2 activity is unclear. Here, we used G221E, G221A, and G221S mutants to assess the role of Gly-221 in HABP2 catalysis. The G221E variant failed to activate the single-chain urokinase-type plasminogen activator, and the G221A and G221S variants displayed moderately reduced single-chain urokinase-type plasminogen activator activation. Activity toward the peptide substrate S-2288 was markedly decreased in all HABP2 variants, with G221E being the most defective and G221A being the least defective. In the absence of Ca²⁺, S-2288 cleavage by wild-type HABP2 was Na⁺-dependent, with K_m decreasing from 3.0 to 0.6 mm upon titration from 0 to 0.3 m Na⁺ In the presence of 5 mm Ca²⁺, K_m was further reduced to 0.05 mm, but without an appreciable contribution of Na⁺ At physiological concentrations of Na⁺ and Ca²⁺, the three HABP2 variants, and particularly G221E, displayed a major K_m increase for S-2288. Chemical footprinting revealed that Ile-16 is significantly less protected from chemical modification in G221E than in wild-type HABP2, suggesting impaired insertion of the N terminus into the G221E protease domain, with a concomitant impact on catalytic activity. Homology modeling suggested that the Glu-221 side chain could sterically hinder insertion of the N terminus into the HABP2 protease domain, helping to explain the detrimental effects of Glu-221 substitution on HABP2 activity.

The HABP2 G534E variant is an unlikely cause of familial non-medullary thyroid cancer

CONTEXT

A recent study reported the non-synonymous G534E (rs7080536, allele A) variant in the HABP2 gene as causal in familial non-medullary thyroid cancer (NMTC).

OBJECTIVE

The objective of this study was to evaluate the causality of HABP2 G534E in the TCUKIN study, a multi-center population based study of NMTC cases from the British Isles.

DESIGN AND SETTING

A case-control analysis of rs7080536 genotypes was performed using 2,105 TCUKIN cases and 5,172 UK controls.

PARTICIPANTS

Cases comprised 2,105 NMTC cases. Patients sub-groups with papillary (N=1,056), follicular (N=691) and Hurthle cell (N=86) TC cases were studied separately. Controls comprised 5,172 individuals from the 1958 Birth Cohort (58C) and the National Blood Donor Service (NBS) study. The controls had previously been genotyped using genome-wide SNP arrays by the Wellcome Trust Case Control Consortium study.

OUTCOME

Measures: Association between HABP2 G534E (rs7080536A) and NMTC risk was evaluated using logistic regression.

RESULTS

The frequency of HABP2 G534E was 4.2% in cases and 4.6% in controls. We did not detect an association between this variant and NMTC risk (OR=0.896, 95% CI: 0.746-1.071, P=0.233). We also failed to detect an association between HABP2 G534E and cases with papillary (1056 cases, G534E frequency= 3.5%, OR=0.74, P=0.017), follicular (691 cases, G534E frequency= 4.7%, OR=1.00, P=1.000) or Hurthle cell (86 cases, G534E frequency= 6.3%, OR=1.40, P=0.279) histology.

CONCLUSIONS

We found that HABP2 G534E is a low-to-moderate frequency variant in the British Isles and failed to detect an association with NMTC risk, independent of histological type. Hence, our study does not implicate HABP2 G534E or a correlated polymorphism in familial NMTC and additional data are required before using this variant in NMTC risk assessment.

Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer

Familial nonmedullary thyroid cancer accounts for 3 to 9% of all cases of thyroid cancer, but the susceptibility genes are not known. Here, we report a germline variant of HABP2 in seven affected members of a kindred with familial nonmedullary thyroid cancer and in 4.7% of 423 patients with thyroid cancer. This variant was associated with increased HABP2 protein expression in tumor samples from affected family members, as compared with normal adjacent thyroid tissue and samples from sporadic cancers. Functional studies showed that HABP2 has a tumor-suppressive effect, whereas the G534E variant results in loss of function.

Factor seven activating protease (FSAP): does it activate factor VII?

BACKGROUND

Factor seven activating protease (FSAP) was initially reported as an activator of single-chain urokinase-type plasminogen activator (scuPA) and factor VII (FVII). Subsequently, numerous additional substrates have been identified, and multiple other biological effects have been reported. Due to the apparent lack of specificity, the physiological role of FSAP has become increasingly unclear. Rigorous studies have been limited by the difficulty of obtaining intact FSAP from blood or recombinant sources.

OBJECTIVES

Our aim was to produce intact recombinant human FSAP, and to assess its role as a trigger of coagulation and fibrinolysis.

RESULTS

Expression of wild-type FSAP in various mammalian cells invariably resulted in the accumulation of degraded FSAP due to autoactivation and degradation. To overcome this problem, we constructed a variant in which Arg(313) at the natural activation site was replaced by Gln, creating a cleavage site for the bacterial protease thermolysin. HEK293 cells produced FSAP(R313Q) in its intact form. Thermolysin-activated FSAP displayed the same reactivity toward the substrate S-2288 as plasma-derived FSAP, and retained its ability to activate scuPA. Polyphosphate and heparin increased V(max) by 2-3-fold, without affecting K(m) (62 nm) of scuPA activation. Surprisingly, FVII activation by activated FSAP proved negligible, even in the presence of calcium ions, phospholipid vesicles and recombinant soluble tissue factor. On membranes of 100% cardiolipin FVII cleavage did occur, but this resulted in transient activation and rapid degradation.

CONCLUSIONS

While FSAP indeed activates scuPA, FVII appears remarkably resistant to activation. Therefore, reappraisal of the putative role of FSAP in hemostasis seems appropriate.

Association of the type 2 diabetes mellitus susceptibility gene, TCF7L2, with schizophrenia in an Arab-Israeli family sample

Many reports in different populations have demonstrated linkage of the 10q24-q26 region to schizophrenia, thus encouraging further analysis of this locus for detection of specific schizophrenia genes. Our group previously reported linkage of the 10q24-q26 region to schizophrenia in a unique, homogeneous sample of Arab-Israeli families with multiple schizophrenia-affected individuals, under a dominant model of inheritance. To further explore this candidate region and identify specific susceptibility variants within it, we performed re-analysis of the 10q24-26 genotype data, taken from our previous genome-wide association study (GWAS) (Alkelai et al, 2011). We analyzed 2089 SNPs in an extended sample of 57 Arab Israeli families (189 genotyped individuals), under the dominant model of inheritance, which best fits this locus according to previously performed MOD score analysis. We found significant association with schizophrenia of the TCF7L2 gene intronic SNP, rs12573128, (p = 7.01×10⁻⁶) and of the nearby intergenic SNP, rs1033772, (p = 6.59×10⁻⁶) which is positioned between TCF7L2 and HABP2. TCF7L2 is one of the best confirmed susceptibility genes for type 2 diabetes (T2D) among different ethnic groups, has a role in pancreatic beta cell function and may contribute to the comorbidity of schizophrenia and T2D. These preliminary results independently support previous findings regarding a possible role of TCF7L2 in susceptibility to schizophrenia, and strengthen the importance of integrating linkage analysis models of inheritance while performing association analyses in regions of interest. Further validation studies in additional populations are required.

The cyclopentapeptide plactin enhances cellular binding and autoactivation of the serine protease plasma hyaluronan-binding protein

Plactin, a family of cyclopentapeptides of fungal origin, enhances fibrinolytic activity by promoting of single-chain urokinase-type plasminogen activator (scu-PA) activation on the cell surface. For this activity, factor(s) in the blood plasma is absolutely required. In the previous studies, we identified prothrombin as a plasma cofactor involved in this mechanism, while the presence of another independent cofactor was suggested. The objective of this study was to identify the second cofactor and investigate the mechanism involved. Using plactin-affinity and ion-exchange chromatographies, we purified plasma hyaluronan-binding protein (PHBP) ~4,000-fold from human plasma as an independent plactin cofactor. PHBP, at ~10nM, was effective in plactin-dependent promotion of scu-PA activation by U937 cells. PHBP is a serine protease that is produced as a single-chain proenzyme (pro-PHBP) and autoproteolytically converted to an active two-chain form. Pro-PHBP was comparable to PHBP in activity to promote plactin-dependent scu-PA activation by U937 cells. Plactin enhanced both cellular binding and autoproteolytic activation of pro-PHBP. The two activities were obtained with a plactin concentration at ~30μM, which resulted in a significant increase in intrinsic fluorescence and self association of pro-PHBP. Thus, it is suggested that such changes account for both enhanced cellular binding and autoactivation of pro-PHBP, resulting in an enhancement of scu-PA activation.

Altered factor VII activating protease expression in murine hepatic fibrosis and its influence on hepatic stellate cells

BACKGROUND

Platelet-derived growth factor-BB (PDGF-BB) is a profibrotic factor in liver fibrosis through its ability to stimulate hepatic stellate cells (HSC). The liver-derived serine protease factor VII activating protease (FSAP) regulates the activities of PDGF-BB in a cell-specific manner.

AIMS

Our aim was to determine the influence of FSAP on the activation of HSC and to analyse the regulation of FSAP in hepatic fibrogenesis.

METHODS

The effect of FSAP on PDGF-stimulated p42/p44 mitogen-activated protein kinase (MAPK) activation in primary rat HSC was determined by Western blotting. Migration and proliferation of HSC was evaluated in Boyden chamber experiments and (3)H-thymidine incorporation assays respectively. Expression of FSAP was analysed in a CCl(4) mouse model of liver fibrosis by Western blot, quantitative real-time polymerase chain reaction and immunohistochemistry.

RESULTS

FSAP inhibited PDGF-BB-stimulated p42/p44 MAPK phosphorylation, proliferation and migration of HSC. FSAP mRNA expression level was increased 3 h after CCl(4) application and decreased after 18 h and, in established fibrosis, after chronic CCl(4) administration. In parallel, there was a decrease in the circulating FSAP protein in chronic fibrosis. Concurrently, the homogenous hepatic expression pattern of FSAP was disturbed. Immunohistochemistry revealed a decrease of FSAP in hepatocytes in inflammatory and fibrotic lesions.

CONCLUSIONS

Our results demonstrate an inhibitory effect of FSAP on PDGF-mediated activation of HSC. In addition, FSAP expression is transiently increased in acute-phase reaction but decreased during chronic fibrogenesis, which in turn may influence PDGF-BB availability and myofibroblast activity.

Correlation of serpin–protease expression by comparative analysis of real-time PCR profiling data

Imbalanced protease activity has long been recognized in the progression of disease states such as cancer and inflammation. Serpins, the largest family of endogenous protease inhibitors, target a wide variety of serine and cysteine proteases and play a role in a number of physiological and pathological states. The expression profiles of 20 serpins and 105 serine and cysteine proteases were determined across a panel of normal and diseased human tissues. In general, expression of serpins was highly restricted in both normal and diseased tissues, suggesting defined physiological roles for these protease inhibitors. A high correlation in expression for a particular serpin-protease pair in healthy tissues was often predictive of a biological interaction. The most striking finding was the dramatic change observed in the regulation of expression between proteases and their cognate inhibitors in diseased tissues. The loss of regulated serpin-protease matched expression may underlie the imbalanced protease activity observed in pathological states.

A positively charged cluster in the epidermal growth factor-like domain of Factor VII-activating protease (FSAP) is essential for polyanion binding

FSAP (Factor VII-activating protease) is a novel plasma-derived serine protease that regulates haemostasis as well as vascular cell proliferation. FSAP undergoes autoactivation in the presence of polyanionic macromolecules such as heparin and RNA. Competition experiments suggest that RNA and heparin bind to the same or overlapping interaction sites. A proteolysis approach, where FSAP was hydrolysed into smaller fragments, was used to identify the polyanion-binding site. The EGF (epidermal growth factor)-like domains EGF2 and EGF3 of FSAP are the major interaction domains for RNA. The amino acids Arg170, Arg171, Ser172 and Lys173 within the EGF3 domain were essential for this binding. This is also the region with the highest positive net charge in the protein and is most probably located in an exposed loop. It is also highly conserved across five species. Disruption of disulphide bridges led to the loss of RNA and heparin binding, indicating that the three-dimensional structure of the EGF3 domain is essential for binding to negatively charged heparin or RNA. The identification of polyanion-binding sites will help to define the role of FSAP in the vasculature.

Factor VII activating protease (FSAP) inhibits growth factor‐mediated cell proliferation and migration of vascular smooth muscle cells

The factor VII activating protease (FSAP) is a serine-protease present in human plasma that serves to activate single-chain plasminogen activators, as well as coagulation factor VII. FSAP was localized within atherosclerotic lesions, and a genetic polymorphism in FSAP is associated with carotid stenosis. Hence, this study was conducted to gain broader insights into the cellular effects of FSAP on vascular smooth muscle cells (VSMC). DNA synthesis and cell proliferation assays revealed an inhibitory action of FSAP on platelet-derived growth factor BB (PDGF-BB)-mediated proliferation of VSMC. FSAP also inhibited PDGF-BB-induced migration of VSMC. These cellular effects of FSAP could be neutralized by an anti-FSAP mAb as well as by protease inhibitors such as aprotinin or a chloromethylketone inhibitor. Moreover, unfractionated heparin promoted the antiproliferative effect of FSAP on VSMC and was essential for the inhibition of VSMC migration. FSAP inhibited PDGF-BB binding to human VSMC and concomitantly blocked PDGF-BB-dependent phosphorylation of mitogen activated protein kinase p42/p44 and tyrosine phosphorylation of other proteins. These results unravel a new function of FSAP as an inhibitor of the proatherogenic phenotype of vascular smooth muscle.

Factor VII activating protease (FSAP): a novel protease in hemostasis

Recently a novel serine protease in human plasma was described and was named PHBP, PHBSP or factor seven activating protease (FSAP), respectively, the latter according to the finding that it can support coagulation by factor VII activation. Later on FSAP was identified as a potent activator of single chain plasminogen activators, in particular of prourokinase, as well. The physiological role of FSAP is still speculative, but recent studies suggest a contribution to hemostasis. Due to its affinity to glycosaminoglycans a role in cell-associated or extracellular proteolytic events is also likely. The impact of a very recently uncovered frequent polymorphism impairing the prourokinase activation potential of FSAP needs to be investigated in more detail.

Hepatic injury-specific conversion of mouse plasma hyaluronan binding protein to the active hetero-dimer form

Plasma hyaluronan binding protein (PHBP) is produced only in liver and kidney in mouse. The induction of PHBP mRNA and the conversion of pro PHBP to the active hetero-dimer form were studied after CCl4, D-galactosamine, HgCl2 or turpentine administration and after partial hepatectomy. The results indicated that the administrations of CCl4 and D-galactosamine, which caused hepatic failure, and the partial hepatectomy enhanced the conversion of pro PHBP to the active two-chain form in the plasma. On the other hand, HgCl2 which injured kidney and turpentine which led to inflammation were not involved in the activation of PHBP. The weak induction and suppression of PHBP mRNA were observed in the liver at 3 h and 12 h, respectively, after the CCl4 administration. However, HgCl2 and turpentine did not influence the amount of PHBP mRNA. These results suggested the hepatic injury-specific activation of PHBP in plasma. PHBP may act as an early factor in the cascade for the tissue remodeling in liver following hepatic injury, i.e., PHBP activates urokinase, urokinase activates matrix metalloproteinases (MMPs) and MMPs degrade extracellular matrix for liver regeneration.