Differential effects of echistatin and thrombin on collagen production and prolidase activity in human dermal fibroblasts and their possible implication in beta1-integrin-mediated signaling

Structure-Function Relationship of the Disintegrin Family: Sequence Signature and Integrin Interaction

Disintegrins are small cysteine-rich proteins found in a variety of snake venom. These proteins selectively modulate integrin function, heterodimeric receptors involved in cell-cell and cell-matrix interaction that are widely studied as therapeutic targets. Snake venom disintegrins emerged from the snake venom metalloproteinase and are classified according to the sequence size and number of disulfide bonds. Evolutive structure and function diversification of disintegrin family involves a stepwise decrease in the polypeptide chain, loss of cysteine residues, and selectivity. Since the structure elucidation of echistatin, the description of the structural properties of disintegrins has allowed the investigation of the mechanisms involved in integrin-cell-extracellular matrix interaction. This review provides an analysis of the structures of all family groups enabling the description of an expanded classification of the disintegrin family in seven groups. Each group presents a particular disulfide pattern and sequence signatures, facilitating the identification of new disintegrins. The classification was based on the disintegrin-like domain of the human metalloproteinase (ADAM-10). We also present the sequence and structural signatures important for disintegrin-integrin interaction, unveiling the relationship between the structure and function of these proteins.

PROLIDASE: A Review from Discovery to its Role in Health and Disease

Prolidase (peptidase D), encoded by the PEPD gene, is a ubiquitously expressed cytosolic metalloproteinase, the only enzyme capable of cleaving imidodipeptides containing C-terminal proline or hydroxyproline. Prolidase catalyzes the rate-limiting step during collagen recycling and is essential in protein metabolism, collagen turnover, and matrix remodeling. Prolidase, therefore plays a crucial role in several physiological processes such as wound healing, inflammation, angiogenesis, cell proliferation, and carcinogenesis. Accordingly, mutations leading to loss of prolidase catalytic activity result in prolidase deficiency a rare autosomal recessive metabolic disorder characterized by defective wound healing. In addition, alterations in prolidase enzyme activity have been documented in numerous pathological conditions, making prolidase a useful biochemical marker to measure disease severity. Furthermore, recent studies underscore the importance of a non-enzymatic role of prolidase in cell regulation and infectious disease. This review aims to provide comprehensive information on prolidase, from its discovery to its role in health and disease, while addressing the current knowledge gaps.

Current Understanding of the Emerging Role of Prolidase in Cellular Metabolism

Prolidase [EC 3.4.13.9], known as PEPD, cleaves di- and tripeptides containing carboxyl-terminal proline or hydroxyproline. For decades, prolidase has been thoroughly investigated, and several mechanisms regulating its activity are known, including the activation of the β₁-integrin receptor, insulin-like growth factor 1 receptor (IGF-1) receptor, and transforming growth factor (TGF)-β₁ receptor. This process may result in increased availability of proline in the mitochondrial proline cycle, thus making proline serve as a substrate for the resynthesis of collagen, an intracellular signaling molecule. However, as a ligand, PEPD can bind directly to the epidermal growth factor receptor (EGFR, epidermal growth factor receptor 2 (HER2)) and regulate cellular metabolism. Recent reports have indicated that PEPD protects p53 from uncontrolled p53 subcellular activation and its translocation between cellular compartments. PEPD also participates in the maturation of the interferon α/β receptor by regulating its expression. In addition to the biological effects, prolidase demonstrates clinical significance reflected in the disease known as prolidase deficiency. It is also known that prolidase activity is affected in collagen metabolism disorders, metabolic, and oncological conditions. In this article, we review the latest knowledge about prolidase and highlight its biological function, and thus provide an in-depth understanding of prolidase as a dipeptidase and protein regulating the function of key biomolecules in cellular metabolism.

Clinical Genetics of Prolidase Deficiency: An Updated Review

Prolidase is a ubiquitous enzyme that plays a major role in the metabolism of proline-rich proteins. Prolidase deficiency is a rare autosomal recessive inborn metabolic and multisystemic disease, characterized by a protean association of symptoms, namely intellectual disability, recurrent infections, splenomegaly, skin lesions, auto-immune disorders and cytopenia. To our knowledge, no published review has assembled the different clinical data and research studies over prolidase deficiency. The aim of this study is to summarize the actual state of the art from the descriptions of all the patients with a molecular diagnosis of prolidase deficiency reported to date regarding the clinical, biological, histopathological features, therapeutic options and functional studies.

The Relationship Between Prolidase Activity and Atrial Electromechanical Changes in Patients with Paroxysmal Atrial Fibrillation

Background:

Tissue fibrosis increases in the structure of the atrial tissue of atrial fibrillation patients. Prolidase enzyme regulates collagen synthesis. There may be an association between electrocardiography (ECG) findings and prolidase activity.

Objective:

This study investigated the association between atrial conduction time and prolidase activity, a collagen synthesis enzyme, and P-wave dispersion (PWD) in patients with Paroxysmal Atrial Fibrillation (PAF).

Methods:

Exclusion criteria included the age of <18 years, heart failure, diabetes, hypertension, hyperlipidemia, malignancy, cerebrovascular disease, chronic respiratory distress, osteoporosis, rheumatoid arthritis, renal disease, cirrhosis, and other types of arrhythmia. Patients diagnosed with PAF within 48 hours were considered to have a definite diagnosis. PWD was calculated using a 12-lead ECG, and inter- and intraatrial electromechanical delay (EMD) was assessed using tissue Doppler imaging and conventional echocardiography. Serum prolidase levels were measured in both groups.

Results:

A total of 43 patients with PAF (20 female, 23 male; mean age, 46.8 ± 5.7 years) and 42 healthy volunteers (21 female, 21 male; mean age, 43.9 ± 5.1 years) were included in the study.

:

Inter- and intraatrial EMD, PWD, minimum P-wave (Pmin), and maximum P-wave (Pmax) measurements were significantly higher (39.7 ± 2.7, 35.7 ± 2.3, p < 0.001; 13.2 ± 2.6, 8.5 ± 1.9, p < 0.001; 47.1 ± 11, 24.1 ± 7.1, p < 0.001; 69.8 ± 8.8, 66.7 ± 10.2, p < 0.130; 114.8 ± 13, 93.6 ± 8.6, p < 0.001, respectively) and serum prolidase levels were significantly lower in patients with PAF compared to healthy controls (3.96 ± 1.2, 8.5 ± 3.56, p < 0.001). In patients with PAF, correlation analysis showed a negative correlation between prolidase levels and intra- and interatrial EMD, PWD, and Pmax (r = -0.41, p < 0.05; r = -0.54, p < 0.05; r = -0.62, p < 0.05; r = -0.49, p < 0.05, respectively). Interatrial EMD showed a significant positive correlation with intraatrial EMD, Pmax, and PWD in patients with PAF (r = 0.90, p < 0.05; r = 0.574, p < 0.05; r = 0.43, p < 0.05, respectively). Additionally, the level of high-sensitivity C-reactive protein (hs-CRP) was significantly higher in patients with PAF (6.6 ± 8, 1.8 ± 1.6, p < 0.001).

Conclusion:

The decreased plasma prolidase activity in patients with PAF may explain the irregularity of the collagen metabolism of different extracellular components and may indicate the onset of atrial remodeling. Changes in PWD, interatrial EMD, and serum prolidase level may predict PAF before diagnosis.

Differential effect of platelet-rich plasma fractions on β1-integrin signaling, collagen biosynthesis, and prolidase activity in human skin fibroblasts

The study was conducted to evaluate the effects of platelet-rich plasma (PRP), supernatant of PRP (SPRP) obtained by centrifugation, and supernatant of activated PRP (SActi-PRP) obtained by Ca²⁺ solution-treated PRP on collagen biosynthesis, prolidase activity, and β1-integrin signaling in cultured human skin fibroblasts. Incubation of fibroblasts with 5% PRP for 24 h contributed to ~5-fold increase in collagen biosynthesis compared to the control. In the cells treated with 5% of SPRP or SActi-PRP, collagen biosynthesis showed a 3-fold increase of the control. PRP, SPRP, and SActi-PRP stimulated prolidase activity similar to collagen biosynthesis. Collagen biosynthesis and prolidase activity are regulated by β1-integrin receptor signaling. Incubation of fibroblasts with PRP for 24 h contributed to a dose-dependent increase in the expression of β1-integrin receptor, while SActi-PRP increased the process to a much lower extent. SPRP had no effect on the β1-integrin receptor expression. All the studied fractions of blood increased the expression of FAK as well as the expression of phosphorylated MAP-kinases. However, PRP was found to be the most effective stimulator of expression of these particular kinases. These studies suggest that a complex of factors, including growth factors, adhesion molecules, and prolidase contained in PRP, all evoke growth and collagen-promoting activities in human dermal fibroblasts.

Synergistic action of cisplatin and echistatin in MDA-MB-231 breast cancer cells

The aim of our study was to determine whether the use of cisplatin in the presence echistatin in MDA-MB-231 breast cancer cells leads to a reduction of toxic effects associated with the use of cisplatin. The expression of β₁-integrin and insulin-like growth factor 1 receptor (IGF-IR), signaling pathway protein expression: protein kinase B (AKT), mitogen-activated protein kinases (ERK1/ERK2), nuclear factor kappa B (NFκB), and caspase-3 and -9 activity was measured after 24 h of incubation with tested compounds to explain detailed molecular mechanism of induction of apoptosis. The viability of MDA-MB-231 breast cancer cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Annexin V-FITC/propidium iodide staining assay was performed to detect the induction of apoptosis. Inhibition DNA biosynthesis was determined by [³H]thymidine incorporation into DNA. The expression of of β₁-integrin, IGF-IR, AKT, ERK1/ERK2, NFκB, caspase-3 and -9 was evaluated using Western blot. The results suggest that treatment of MDA-MB-231 breast cancer cells for 24 h cisplatin plus echistatin severely inhibits cell growth and activates apoptosis by upregulation of caspase-3 and -9 expressions. The effect was stronger than treatment cisplatin and echistatin alone. In this study, we have found that cisplatin plus echistatin treatment decreases collagen biosynthesis in MDA-MB-231 breast cancer cells stronger than the individual compounds. The inhibition was found to be dependent on the β₁-integrin and IGF receptor activation. A significant reduction of ERK1/ERK2, AKT expression in cancer cells after cisplatin plus echistatin treatment was also found. The cancer cells treated by echistatin, cisplatin, and in particular the combination of both compounds drastically increased expression of NFκB transcription factor. Our results suggest that combined therapy cisplatin plus echistatin is a possible way to improve selectiveness of cisplatin. This mechanism probably is due to downregulation of expression of β₁-integrin and IGF-IR receptors, and the signaling pathway proteins induced by these receptors. Our results suggest that therapy cisplatin plus echistatin is a possible way to improve selectiveness of cisplatin.

Metalloproteases Affecting Blood Coagulation, Fibrinolysis and Platelet Aggregation from Snake Venoms: Definition and Nomenclature of Interaction Sites

Snake venom metalloproteases, in addition to their contribution to the digestion of the prey, affect various physiological functions by cleaving specific proteins. They exhibit their activities through activation of zymogens of coagulation factors, and precursors of integrins or receptors. Based on their structure–function relationships and mechanism of action, we have defined classification and nomenclature of functional sites of proteases. These metalloproteases are useful as research tools and in diagnosis and treatment of various thrombotic and hemostatic conditions. They also contribute to our understanding of molecular details in the activation of specific factors involved in coagulation, platelet aggregation and matrix biology. This review provides a ready reference for metalloproteases that interfere in blood coagulation, fibrinolysis and platelet aggregation.

Prolidase-proline dehydrogenase/proline oxidase-collagen biosynthesis axis as a potential interface of apoptosis/autophagy

Prolidase is a cytosolic imidodipeptidase that specifically splits imidodipeptides with C-terminal proline or hydroxyproline. The enzyme plays an important role in the recycling of proline from imidodipeptides for resynthesis of collagen and other proline-containing proteins. The mechanism of prolidase-dependent regulation of collagen biosynthesis was found at both transcriptional and post-transcriptional level. The increase in the enzyme activity is due to its phosphorylation on serine/threonine residues. Prolidase-dependent transcriptional regulation of collagen biosynthesis was found at the level of NF-κB, known inhibitor of type I collagen gene expression. Proline dehydrogenase/proline oxidase (PRODH/POX) is flavin-dependent enzyme associated with the inner mitochondrial membrane. The enzyme catalyzes conversion of proline into Δ(1) -pyrroline-5-carboxylate (P5C), during which reactive oxygen species (ROS) are produced, inducing intrinsic and extrinsic apoptotic pathways. Alternatively, under low glucose stress, PRODH/POX activation produces ATP for energy supply and survival. Of special interest is that PRODH/POX gene is induced by P53 and peroxisome proliferator-activated gamma receptor (PPARγ). Among down-regulators of PRODH/POX is an oncogenic transcription factor c-MYC and miR-23b*. On the other hand, PRODH/POX suppresses HIF-1α transcriptional activity, the MAPK pathway, cyclooxygenase-2, epidermal growth factor receptor and Wnt/b-catenin signaling. PRODH/POX expression is often down-regulated in various tumors, limiting mitochondrial proline utilization to P5C. It is accompanied by increased cytoplasmic level of proline. Proline availability for PRODH/POX-dependent ATP or ROS generation depends on activity of prolidase and utilization of proline in process of collagen biosynthesis. Therefore, Prolidase-PRODH/POX-Collagen Biosynthesis axis may represent potential interface that regulate apoptosis and survival. © 2016 BioFactors, 42(4):341-348, 2016.

Combined therapy with disintegrin and melphalan as a new strategy in inhibition of endometrial cancer cell line (Ishikawa) growth

Endometrial cancer is one of the most frequently diagnosed cancer in females with prevalence of 22 in 100,000 women. The etiology of the cancer remains unclear. Despite significant progress towards understanding the patho-mechanism of the disease, effective treatment is still lacking. The results of the study suggest that combined treatment of Ishikawa cells for 24 h with disintegrin and then for 24 h with melphalan severely inhibits important biological functions of the cells. We showed that such strategy have a potent cytotoxic effect. The mechanism of process undergoes probably through inhibition of integrin - dependent signaling. In this study we shown down regulation of Shc and FAK proteins in cells treated with echistatin and melphalan. It suggests that signaling pathways that involve Shc and FAK participation may represent target for antineoplastic strategy. The functional significance of the combined treatment of Ishikwa cells with echistatin and melphalan was found at the level of collagen biosynthesis. Decreased biosynthesis of collagen in extracellular matrix may suppress cell growth and induce apoptosis. The treatment with echistatin and melphalan also showed decreased expression of IGF receptor in comparison to the cells treated with both compounds separately. The data presented suggest that combined therapy with disintegrin - echistatin and alkyalting drug - mephalan may represent a new approach to more effective and safe cancer therapy.

Proliferation and adhesion capability of human gingival fibroblasts onto zirconia, lithium disilicate and feldspathic veneering ceramic in vitro

Human gingival fibroblasts (HGFs) were cultured onto CAD/CAM zirconia (Group A), CAD/CAM zirconia after polishing (Group B), CAD/CAM lithium disilicate after polishing (Group C), and feldspathic ceramic (Group D) to evaluate their proliferation and adhesion potential. After 3 h, HGF adhesion was similar in all groups. Later, HGFs closely adhered to surfaces, particularly onto groups B, C and D, acquiring an elongated shape. Proliferation assay showed no differences in cell viability among the groups after 24 h, while significant increase was shown after 72 h in Groups B and C. After 24 h, similar Collagen I levels were found in all groups, while after 72 h Groups B and C revealed a deep reduction in respect to the 24 h level. In vitro, HGF behavior may reflect variability in soft tissue response to different surface materials for prosthetic restorations, and support that polished zirconia is able to achieve a better integration in vivo in respect to the other materials.

A dual role for β1 integrin in an in vitro Streptococcus mitis/human gingival fibroblasts co-culture model in response to TEGDMA

AIM

To evaluate the effect of TEGDMA on human gingival fibroblasts (HGFs) in vitro co-cultured with Streptococcus mitis, focusing on the signalling pathways underlying cell tissue remodelling and inflammatory response processes.

METHODOLOGY

β1 integrin expression was evaluated by means of imaging flow cytometry. The Western blot technique was used to investigate the expression of protein kinase C (PKC), extracellular signal-regulated kinase (ERK), matrix metalloproteinase 9 (MMP9) and 3 (MMP3). RT-PCR was performed to quantify nuclear factor-kb subunits (Nf-kb1, ReLa), IkB kinase β (IkBkB), cyclooxygenase II (COX-2) and tumour necrosis factor-α (TNF-α) mRNA levels. Statistical analysis was performed using the analysis of variance (anova).

RESULTS

When HGFs are co-cultured with S. mitis, β1 integrin intensity, phosphorylated PKC (p-PKC), activated ERK (p-ERK), IkBkB mRNA level and MMP9 expression increased (for all molecules P < 0.05 HGFs versus HGFs co-cultured with S. mitis). A higher level of MMP3 in HGFs treated with TEGDMA was recorded (P < 0.05 HGFs versus HGFs exposed to TEGDMA). COX-2 inflammatory factor mRNA level appeared higher in HGFs exposed to 1 mmol L(-1) TEGDMA (P < 0.01 HGFs versus HGFs exposed to TEGDMA), whereas TNF-α gene expression was higher in HGFs co-cultured with S. mitis (P < 0.05 HGFs versus HGFs co-cultured with S. mitis).

CONCLUSIONS

β1 integrin triggered the signalling pathway, transduced by p-PKCα and involving ERK 1 and 2 and MMPs. This pathway resulted in an unbalanced equilibrium in tissue remodelling process, along with inflammatory response when HGFs are exposed to bacteria or biomaterial alone. On the contrary, the TEGDMA/S. mitis combination restored the balance between extracellular matrix deposition and degradation and prevented an inflammatory response.

Prolidase is required for early trafficking events during influenza A virus entry

Influenza A virus (IAV) entry is a multistep process that requires the interaction of the virus with numerous host factors. In this study, we demonstrate that prolidase (PEPD) is a cellular factor required by IAV for successful entry into target cells. PEPD was selected as a candidate during an entry screen performed on nonvalidated primary hits from previously published genome-wide small interfering RNA (siRNA) screens. siRNA-mediated depletion of PEPD resulted in the decreased growth of IAV during mono- and multicycle growth. This growth defect was independent of cell type or virus strain. Furthermore, IAV restriction was apparent as early as 3 h postinfection, and experiments in the absence of protein biosynthesis revealed that the nuclear import of viral ribonucleoprotein complexes (vRNPs) was already blocked in the absence of PEPD. These results led us to investigate which step during entry was affected. Receptor expression, IAV attachment, or IAV internalization was not dependent on the presence of PEPD. However, when looking at the distribution of incoming IAV particles in PEPD-knockdown cells, we found a localization pattern that differed from that in control cells: IAV mostly localized to the cell periphery, and consequently, viral particles displayed reduced colocalization with early and late endosome markers and fusion between viral and endosomal membranes was strongly reduced. Finally, experiments using a competitive inhibitor of PEPD catalytic activity suggested that the enzymatic function of the dipeptidase is required for its proviral effect on IAV entry. In sum, this study establishes PEPD as a novel entry factor required for early endosomal trafficking of IAV.

IMPORTANCE

Influenza A virus (IAV) continues to be a constant threat to public health. As IAV relies on its host cell for replication, the identification of host factors required by the virus is of importance. First, such studies often reveal novel functions of cellular factors and can extend our knowledge of cellular processes. Second, we can further our understanding of processes that are required for the entry of IAV into target cells. Third, the identification of host factors that contribute to IAV entry will increase the number of potential targets for the development of novel antiviral drugs that are of urgent need. Our study identifies prolidase (PEPD) to be a novel entry factor required by IAV for correct routing within the endosomal compartment following virus internalization. Thereby, we link PEPD, which has been shown to play a role during collagen recycling and growth factor signaling, to early events of viral infection.

Cross-talk between integrin receptor and insulin-like growth factor receptor in regulation of collagen biosynthesis in cultured fibroblasts

PURPOSE

Cellular processes are regulated by signals generated by adhesion receptors and growth factor receptors. IGFbinding protein 1 (IGFBP-1) is a molecule which may affect the both signaling pathways through inactivation of IGF-I (ligand for IGF-IR) and binding to RGD region of integrin receptors. Whether this phenomenon is important in communication between insulin-like growth factor receptor (IGF-IR) and β1-integrin receptor in regulation of prolidase activity and collagen biosynthesis is the aim of this study.

MATERIAL AND METHOD

We studied the effects of IGFBP-1, IGF-I, thrombin (integrin activator), echistatin (disintegrin), phosphatidylinositol 3-kinase inhibitor (LY-294002) and ERK 1/2 inhibitors (PD98059 and UO126) on prolidase activity, collagen biosynthesis and expression of proteins participating in pathways generated by these receptors.

RESULTS

Stimulation of β1-integrin and IGF-I receptors by standard ligands was proved to up-regulate collagen synthesis in cultured fibroblasts. IGFBP-1, similarly as echistatin and studied inhibitors, contributed to down-regulation of ERK1/2, Akt, mTOR expression and up-regulation of NFκB. It was accompanied by parallel decrease in prolidase activity and collagen biosynthesis.

CONCLUSION

The data suggest that "cross talk" between IGF-I receptor and integrin receptor may play important role in regulation of prolidase activity and collagen biosynthesis.

Applications of snake venom components to modulate integrin activities in cell-matrix interactions

Snake venom proteins are broadly investigated in the different areas of life science. Direct interaction of these compounds with cells may involve a variety of mechanisms that result in diverse cellular responses leading to the activation or blocking of physiological functions of the cell. In this review, the snake venom components interacting with integrins will be characterized in context of their effect on cellular response. Currently, two major families of snake venom proteins are considered as integrin-binding molecules. The most attention has been devoted to the disintegrin family, which binds certain types of integrins through specific motifs recognized as a tri-peptide structurally localized on an integrin-binding loop. Other snake venom integrin-binding proteins belong to the C-type lectin family. Snake venom molecules bind to the cellular integrins resulting in a modulation of cell signaling and in consequence, the regulation of cell proliferation, migration and apoptosis. Therefore, snake venom research on the integrin-binding molecules may have significance in biomedicine and basic cell biology.

The effect of Telmisartan on collagen biosynthesis depends on the status of estrogen activation in breast cancer cells

PPAR-gamma and estrogen receptor belong to a family of nuclear hormone receptors that were shown to affect transcriptional activity of each other. The angiotensin II type 1 receptor antagonist Telmisartan is a well known PPAR-gamma ligand. The effect of Telmisartan-induced PPAR-gamma activation on collagen biosynthesis was studied in the estrogen-dependent (MCF-7 cells expressing alpha and beta receptors) and estrogen-independent (MDA-MB 231, expressing only beta receptor) cell lines. We have found that the presence of estrogen in growth medium (2nM) augmented collagen biosynthesis in both cell lines. An addition to the growth medium of PPAR-gamma agonist, Telmisartan, but not rosiglitazone or clofibrat, other PPAR-gamma agonists, induced inhibition of collagen biosynthesis in MCF-7 cells, cultured in the presence of estrogen, while it had no effect on collagen biosynthesis in MDA-MB-231 cells. On the other hand, Telmisartan induced stimulation of collagen biosynthesis in MCF-7 cells cultured in the absence of estrogen (or in conditions of estrogen receptor removal by ICI 182-780-dependent degradation) and had no effect on similarly cultured MDA-MB-231 cells. The effect of Telmisartan on collagen biosynthesis was found specific for PPAR-gamma and not for angiotensin II type 1 since Losartan (specific antagonist of angiotensin II type 1 receptor) in the presence of estradiol did not induce inhibition of this protein in MCF-7 cells. The mechanism of the inhibition was found at the level of NF-kB (known inhibitor of collagen gene expression) and MAPK signaling. PPAR-gamma ligands stimulated expression of NF-kB, while they inhibited expression of p-38 but not ERK1/ERK2. The data suggest that the effect of Telmisartan on collagen biosynthesis in breast cancer cells depends on the status of estrogen receptor activation and the inhibitory effect of Telmisartan on the process requires functional alpha estrogen receptor.

Assessment of preoperative serum prolidase activity in epithelial ovarian cancer

OBJECTIVE

Prolidase is a cytosolic exopeptidase that cleaves iminodipeptides with C-terminal proline and hydroxyproline and plays a major role in collagen turnover. The aim of this study was to evaluate preoperative serum prolidase activity, total oxidant status (TOS), and total antioxidant capacity (TAC) in patients with newly diagnosed epithelial ovarian cancer (EOC).

STUDY DESIGN

Serum prolidase activity, TOS, and TAC were measured spectrophotometrically in both EOC cases (n=28) and controls (n=28).

RESULTS

Preoperative serum prolidase activity and TOS were significantly higher in patients with EOC compared to controls (p=0.009 and 0.008, respectively), whereas TAC was significantly lower in cases (p<0.001). A significant positive correlation was found between the stage, grade, and CA-125 level of EOC and serum prolidase activity (rho=0.466, p=0.012; rho=0.501, p=0.007; and rho=0.447, p=0.017, respectively) and TOS (rho=0.588, p=0.001; rho=0.412, p=0.029; and rho=0.568, p=0.002, respectively). In contrast, there was a negative correlation between TAC and the stage, grade, and CA-125 level of EOC (rho=-0.555, p=0.002; rho=-0.566, p=0.002; and rho=-0.581, p=0.001, respectively).

CONCLUSION

Findings of the present study demonstrate that serum prolidase activity is significantly associated with the stage, tumor grade, and preoperative CA-125 level of EOC.

The association of serum prolidase activity with the presence and severity of coronary artery disease

OBJECTIVES

Prolidase is a cytosolic exopeptidase that cleaves iminodipeptides with carboxy-terminal proline or hydroxyproline and plays major role in collagen turnover. Collagen is the essential content in atherosclerotic plaque playing a key role in the stability/instability of and progression of coronary artery disease (CAD). Consequently, in this study we sought to determine serum prolidase activity and markers of oxidative stress such as lipid hydroperoxide and total free sulfhydryl in CAD.

DESIGN AND METHODS

We have evaluated 199 patients with CAD and 122 control cases with clinical, electrocardiographic, and laboratory investigation. We have measured serum prolidase activity and serum total free sulfhydryl levels spectrophotometrically. Serum lipid hydroperoxide levels were determined with ferrous ion oxidation-xylenol orange method. We assessed the association of serum prolidase activity with the presence and severity of CAD and clinical characteristics, and laboratory parameters.

RESULTS

Serum prolidase activity (52.5+/-5.6 vs. 46.7+/-5.1 U/l, respectively, P<0.001) and serum lipid hydroperoxide levels were significantly increased in patients with CAD compared with control cases whereas, serum total free sulfhydryl levels were significantly decreased in patients with CAD compared with control cases. Serum prolidase activity and total free sulfhydryl levels were independent predictors of the presence of CAD [(chi=75.532, ss=0.212, P=0.003) and (chi=25.969, ss=-30.486, P=0.019), respectively] and Gensini score [(beta=0.276, P<0.001) and (beta=-0.274, P<0.001), respectively]. Independent predictors of serum prolidase activity were serum high-density lipoprotein cholesterol (beta=-0.138, P=0.023) and urea levels (beta=0.146, P=0.036), and Gensini score (beta=0.317, P<0.001).

CONCLUSION

Findings of this study have shown that serum prolidase activity is significantly associated with the presence and severity of CAD, and elevated serum prolidase activity might be an independent predictor of coronary atherosclerosis.

Association of prolidase activity, oxidative parameters, and presence of atrial fibrillation in patients with mitral stenosis

BACKGROUND

Mitral stenosis (MS) is a common cause of atrial fibrillation (AF). Oxidative stress and inflammation factors were shown to be involved in atrial remodeling. The study aim was to compare the oxidative parameters and prolidase activity in severe MS patients with and without AF.

METHODS

The study population was comprised of 33 patients with MS and sinus rhythm (group I), 27 patients with MS and AF (group II), and 25 healthy controls (group III). Plasma prolidase activity, total antioxidant capacity (TAC), total oxidative status (TOS), and oxidative stress index (OSI) were determined. Additionally, we measured tissue TOS and TAC in patients with mitral valve replacement.

RESULTS

TAC and OSI were higher, but TOS and prolidase were lower in patients with MS than control (all p <0.001). These parameters were similar in group I and group II (ANOVA p >0.05). Tissue TAC was significantly lower in group II than group I (0.015 +/- 0.01 vs. 0.026 +/- 0.01 mmol Trolox equiv/L, p = 0.014), tissue TOS was similar between groups I and II (0.24 +/- 0.06 vs. 0.22 +/- 0.05 mmol Trolox equiv/L, p = 0.161). Presence of AF was correlated with systolic blood pressure, left atrial diameter, plasma TAC, tissue TAC, plasma TOS, plasma OSI, and plasma prolidase activity. Tissue TAC level (beta = -0.435, p = 0.006) and left atrial diameter (beta = 0.460, p = 0.003) were independently related with presence of AF in patients with MS.

CONCLUSIONS

This study suggested that the presence of AF in patients with severe MS may be associated with the plasma prolidase activity, tissue and plasma oxidative parameters.

Prolidase-dependent regulation of collagen biosynthesis

Prolidase [EC.3.4.13.9] is a cytosolic imidodipeptidase, which specifically splits imidodipeptides with C-terminal proline or hydroxyproline. The enzyme plays an important role in the recycling of proline from imidodipeptides (mostly derived from degradation products of collagen) for resynthesis of collagen and other proline-containing proteins. The enzyme activity is up-regulated by beta(1)-integrin receptor stimulation. The increase in the enzyme activity is due to its phosphorylation on serine/threonine residues. Collagen is not only structural component of extracellular matrix. It has been recognized as a ligand for integrin receptors, which play an important role in signaling that regulate ion transport, lipid metabolism, kinase activation and gene expression. Therefore, changes in the quantity, structure and distribution of collagens in tissues may affect cell signaling, metabolism and function. Several line of evidence suggests that prolidase activity may be a step-limiting factor in the regulation of collagen biosynthesis. It has been shown in different physiologic and pathologic conditions. It is of great importance during wound healing, inflammation, aging, tissue fibrosis and possibly skeletal abnormalities seen in Osteogenesis Imperfecta. The mechanism of prolidase-dependent regulation of collagen biosynthesis was found at both transcriptional and post-transcriptional levels. In this study, we provide evidence for prolidase-dependent transcriptional regulation of collagen biosynthesis. The mechanism was found at the level of NF-kB, known inhibitor of type I collagen gene expression. Modulation of integrin-dependent signaling by stimulatory (i.e. thrombin) or inhibitory (i.e. echistatin) beta(1)-integrin ligands or by nitric oxide donors (i.e. DETA/NO) affect prolidase at post-transcriptional level. All those factors may represent novel approach to pharmacotherapy of connective tissue disorders.

Serum prolidase activity in patients with hypertension and its relation with left ventricular hypertrophy

OBJECTIVES

The purpose of this study was to determine serum prolidase activity in patients with hypertension and its relation with left ventricular hypertrophy.

DESIGN AND METHODS

Serum prolidase activity was measured spectrophotometrically in hypertensive patients with (Group II, n=30) and without left ventricular hypertrophy (Group III, n=30) and in control group (Group I, n=30).

RESULTS

Prolidase activity was significantly lower in Group I than in Groups II and III (44.64+/-6.42 U/L vs. 54.14+/-6.30 U/L and 54.25+/-7.14 U/L, respectively; ANOVA, p<0.001). We revealed significant correlation between prolidase activity and presence and duration of hypertension (both of p<0.05) but not left ventricular mass index. Multivariate analysis shown that prolidase activity was significantly associated with age (beta=0.481, p<0.001) and duration of hypertension (beta=0.396, p<0.001).

CONCLUSIONS

Our data show that serum prolidase activity is associated with the presence hypertension independent of left ventricular hypertrophy.

Butyrate-induced collagen biosynthesis in cultured fibroblasts is independent on alpha2beta1 integrin signalling and undergoes through IGF-I receptor cascade

The potential role of butyrate to modulate cellular metabolism through integrin receptor led to evaluation of its effect on collagen biosynthesis in cultured fibroblasts. Confluent human dermal fibroblasts were treated with 2 mM and 4 mM of sodium butyrate (NaB) for 48 h. It was found that butyrate induced collagen biosynthesis and prolidase activity independently of alpha2beta1 integrin signaling. The expressions of both alpha2 and beta1 integrin subunits as well as integrin-induced activation of focal adhesion kinase (FAK) were not affected in the cells treated with NaB. Since insulin-like growth factor-I (IGF-I) is the most potent stimulator of collagen biosynthesis in fibroblasts, the effect of butyrate on IGF-I receptor (IGF-IR) expression was evaluated. It was found that the exposure of the cells to 4 mM butyrate contributed to a distinct increase in IGF-IR. It was accompanied by a parallel increase in the expression of Sos protein and MAP-kinases (ERK1, ERK2). The data suggests that butyrate-dependent stimulation of collagen biosynthesis in cultured human skin fibroblasts undergoes through IGF-IR signaling.

Induction of interleukin-8 secretion and activation of ERK1/2, p38 MAPK signaling pathways by thrombin in dermal fibroblasts

It was reported that thrombin could induce IL-8 secretion from human dermal fibroblasts (HDFs) through activation of proteinase activated receptor (PAR)-1. However, little is known of intracellular signaling pathways involved in the event. In the present study, expression of PARs in primarily cultured HDFs was determined by flow cytometry analysis and reverse transcription polymerase chain reaction (RT-PCR), levels of IL-8 were determined by using ELISA and signaling pathways were examined by using Western blot. It was found that HDFs express PAR-1 and PAR-3, and thrombin induces approximately 7.4-fold increase in IL-8 secretion from HDFs. Hirudin and a PAR-1 blocking antibody completely abolish the action of thrombin. It was also found that PD98059, a mitogen-activated protein kinase (MAPK) pathway inhibitor and U0126, an inhibitor of extracellular signal-regulated kinase (ERK) blocks thrombin-induced phosphorylation of ERK1/2 and IL-8 secretion, indicating the involvement of MAPK/ERK signaling pathway in thrombin-induced IL-8 secretion. p38 MAPK pathway appears also being involved as SB203580, a selective inhibitor of p38 MAPK inhibit phosphorylation of p38 MAPK and thrombin-induced IL-8 secretion. Furthermore, Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway, but not phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathway may also be activated by thrombin. In conclusion, thrombin potently induce IL-8 release via PAR-1 from HDFs. Thrombin elicited IL-8 release is predominantly conducted through MAPK/ERK and p38 MAPK signaling pathways. Discovery of the signaling pathways of thrombin in HDFs may help to understand the role of thrombin in inflammation and tissue remodeling.