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Effects of alveolar macrophage conditioned media from interstitial lung disease patients on the procollagen mRNA expression in human lung fibroblasts.

Progressive inflammation and fibrosis are the central processes in the pathogenesis of pulmonary fibrosis. It is believed that macrophages in areas of chronically inflamed lung play a key role in fibrotic response. Therefore, we investigated the effects of alveolar macrophage (Am phi) conditioned media from interstitial lung disease (ILD) patients on lung fibroblast proliferation and procollagen mRNA expression. After stimulating with Am phi conditioned media from ILD patients, the fibroblast proliferation increased 71.4% compared with the control, but for media from bronchial carcinoma (BC) patients, it just increased 14.3%. There is a significant difference between the two groups (P < 0.05). The procollagen alpha, (I) mRNA in fibroblasts stimulated with Am phi conditioned media from ILD patients was increased 21.3%, and alpha 1 (III) was 37.2% higher than control (P < 0.05). It increased 6.8% and 12.8% for media from BC patients respectively, but there was no difference when compared to the control. We considered that Am phi from ILD patients might be in an activated state and could release some growth factors to stimulate fibroblast proliferation and promote collagen DNA expression.

Carcinoma, Bronchogenic↗

In vitro procollagen synthesis and proliferative phenotype of bronchial fibroblasts from normal and asthmatic subjects.

Asthma is characterized histologically by a bronchial subepithelial fibrosis. Cytokines and other mediators released in the asthmatic chronic inflammatory microenvironment can activate the repair process that leads to fibroblast proliferation and collagen synthesis. To our knowledge, there are no data regarding the effect of a chronic inflammatory microenvironment on the phenotype of human bronchial fibroblasts. In the present study, we address this issue by comparing bronchial fibroblasts isolated from normal and asthmatic subjects in terms of: (a) proliferation over cell passage; (b) in vitro lifespan; (c) proliferative response to transforming growth factor-beta 1, platelet-derived growth factor-BB, dexamethasone, and retinoic acid; and (d) base-line synthesis of procollagens I and III. Bronchial fibroblasts from asthmatic subjects demonstrated lower DNA synthesis with cell passage than bronchial fibroblasts from normals. The in vitro lifespan of asthmatic bronchial fibroblasts was lower than in those from normal subjects and was significantly correlated with airway responsiveness. Platelet-derived growth factor-BB and dexamethasone increased 3H-thymidine incorporation in asthmatic bronchial fibroblasts without having any significant effect on normal fibroblast proliferation. Transforming growth factor-beta 1 and retinoic acid had no significant effect on bronchial fibroblast proliferation. Base-line procollagens I and III synthesis measurements showed no differences between normal and asthmatic fibroblasts. Taken together, these results indicate that the chronic inflammatory microenvironment found in asthma can modulate some aspects of bronchial fibroblast phenotype.

Adult↗

Serum concentrations of laminin P1 and aminoterminal propeptide of type III procollagen in sickle cell disease.

We determined serum levels of laminin and aminoterminal propeptide of type III procollagen (PIIINP) in 20 patients with sickle cell hemoglobinopathies. Elevated levels of soluble laminin and PIIINP were observed in the patients--1.5 +/- 0.3 U/ml (mean +/- SD) (range 1.1-1.9 U/ml) and 0.90 +/- 0.2 U/ml (range 0.6-1.4 U/ml), respectively, compared to normal controls, 1.3 +/- 0.1 U/ml (range 1.2-1.4 U/ml) for laminin and 0.7 +/- 0.1 U/ml (range 0.6-0.9 U/ml) for PIIINP. The serum laminin and PIIINP were significantly elevated (p < 0.02 and p < 0.001, respectively, in patients with sickle cell hemoglobinopathies). There was no correlation between serum laminin and PIIINP levels in the patient group. The study indicates that aminoterminal propeptide of type III procollagen and laminin can be utilized as valuable non-invasive markers of possible alterations in extracellular matrix in bone marrow, spleen, kidney or other tissues in sickle cell hemoglobinopathies.

Adolescent↗

Diminished transforming growth factor beta2 production leads to increased expression of a profibrotic procollagen alpha2 type I messenger RNA variant in embryonic fibroblasts of UCD-200 chickens, a model for systemic sclerosis.

OBJECTIVE: A procollagen alpha2(I) messenger RNA (mRNA) variant, with a 115-bp band and an expected band of 180 bp, was found to be increased during early, acute scleroderma-like disease in UCD-200 chickens. The present study investigated the influence of cytokines on the expression of these 2 proalpha2(I) mRNA variants. METHODS: Embryonic fibroblasts of UCD-200 chickens (UCD-200-CEF) and normal white leghorns (NWL-CEF) were grown in 3-dimensional collagen gels. Procollagen mRNA expression was analyzed by RNase protection assay, and proliferation was determined by (3)H-thymidine incorporation. Transforming growth factor beta1 (TGFbeta1) and TGFbeta2 were measured in culture supernatants by enzyme-linked immunosorbent assay. RESULTS: Compared with NWL-CEF, UCD-200-CEF expressed 7.2 times more of the smaller profibrotic proalpha2(I) mRNA variant. TGFbeta1 stimulated the proliferation of UCD-200-CEF, but not NWL-CEF. The 115 bp:180 bp ratio was increased by TGFbeta1 in both NWL-CEF and UCD-CEF. TGFbeta2 and TGFbeta3 reduced the expression of the profibrotic proalpha2(I) mRNA in UCD-200-CEF to the same levels observed in healthy control NWL-CEF. In culture supernatants, NWL-CEF produced 4.1 times more TGFbeta2 than that produced by UCD-CEF. Inhibition of endogenous TGFbeta2 in NWL-CEF resulted in the same 115 bp:180 bp ratio as seen in untreated UCD-CEF. CONCLUSION: TGFbeta2 reduces the expression of a profibrotic proalpha2(I) mRNA variant in UCD-200-CEF. The constitutive overproduction of this proalpha2(I) mRNA variant and the diminished synthesis of TGFbeta2 in untreated UCD-200-CEF suggest that TGFbeta2 can act as an antifibrotic cytokine and might be a key player during fibrosis onset. These results shed light on the contradictory observations regarding the role of TGFbeta2 in human systemic sclerosis.

Animals↗

Up-regulation of type I procollagen C-proteinase enhancer protein messenger RNA in rats with CCl4-induced liver fibrosis.

Using a polyclonal antibody raised against a liver stellate cell (LSC) line derived from a rat CCl4-cirrhotic liver, we isolated 14 clones from a complementary DNA library prepared with total RNA extracted from the same cell line, with nucleotide sequences homologous to that of the type I procollagen C-proteinase enhancer protein (PCPE) gene. The longest PCPE insert of 1,530 base pairs contained an open reading frame coding for 468 amino acids. PCPE cDNA recognized by Northern blot a 1.7-kilobase messenger RNA (mRNA) in total RNA extracted from freshly isolated and early passaged LSC, LSC lines derived from normal (NFSC) and cirrhotic (CFSC) rat livers, and various LSC clones derived from CFSC. The expression of PCPE mRNA was increased threefold in CFSC compared with NFSC. PCPE mRNA was not detected in total rat liver, freshly isolated hepatocytes, or endothelial or Kupffer cells. However, the expression of PCPE mRNA was induced in fibrotic livers of rats treated with CCl4. PCPE mRNA expression in LSC was up-regulated by transforming growth factor beta1 (TGF-beta1) and down-regulated by tumor necrosis factor alpha (TNF-alpha), similar to the changes in alpha1 (1) procollagen mRNA induced by these cytokines. PCPE was not detectable in liver biomatrix proteins obtained from normal liver. However, PCPE was increased in liver biomatrix proteins from cirrhotic livers and was proportional to the amount of collagen. These data suggest that PCPE may play an important role in the processing of type I collagen during liver fibrogenesis, and that TGF-beta1 and TNF-alpha regulate its expression.

Amino Acid Sequence↗

Leucine stimulates procollagen alpha1(I) translation on hepatic stellate cells through ERK and PI3K/Akt/mTOR activation.

The essential amino acid leucine has been described to specifically activate signaling pathways leading to the activation of the translational machinery and the increase of total protein synthesis. Regulation of type I collagen production by hepatic stellate cells (HSC) is a multistep process involving transcriptional and post-transcriptional mechanisms. In the present work we studied the effect of leucine on translation regulation of collagen alpha1(I) production in HSC and the signaling pathways involved. Treatment of HSC with 5 mM leucine did not alter half-life or steady state levels of procollagen alpha1(I) mRNA, but caused an increase in procollagen alpha1(I) protein that correlated with changes of components involved in translational regulation, like enhanced 4E-BP1, Mnk-1, and eIF4E phosphorylation. Leucine also induced mTOR, ERK, and Akt phosphorylation in HSC, without affecting p38 and JNK activation. Pre-treatment of HSC with PD098059, wortmannin, or rapamycin prevented the profibrogenic action of leucine due to the inhibition of different molecular mechanisms. These results suggest leucine is a profibrogenic agent for HSC, activating signaling pathways that lead to an enhancement of collagen alpha1(I) production through translational regulation.

Cells, Cultured↗

Inhibition of type I procollagen production by tRNAVal CTE-HSP47 ribozyme.

BACKGROUND: Fibrosis characteristically occurs in the advanced stages of chronic inflammatory diseases, occasionally as the primary lesion, and frequently determines the disease prognosis. Fibrotic lesions consist mostly of collagen, and therefore it may be possible to prevent or treat fibrosis by inhibiting collagen production. Of the currently available therapeutic approaches, however, none is sufficiently effective and specific for inhibition of collagen. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that has been reported to play a pivotal role in secretion of procollagen molecules. Therefore, we have tried to suppress its function to inhibit these various types of collagen. METHODS: We have developed a novel type of ribozyme by ligating a hammerhead sequence to a tRNA(Val) promoter to facilitate displacing the ribozyme from nucleus to cytoplasm and to constitutive transport element, a binding motif of helicase which unwinds mRNA to render the target sequence on the mRNA accessible to the ribozyme. RESULTS: The ribozyme thus constructed showed strong activity to cleave HSP47 mRNA and suppress the secretion of type I procollagen in the human primary fibroblast. CONCLUSION: We suggest applicability of this ribozyme as a new modality for antifibrosis therapy.

Antisense Elements (Genetics)↗

Two assays for measuring fibrosis: reverse transcriptase-polymerase chain reaction of collagen alpha(1) (III) mRNA is an early predictor of subsequent collagen deposition while a novel serum N-terminal procollagen (III) propeptide assay reflects manifest fibrosis in carbon tetrachloride-treated rats.

Using a novel quantitative reverse transcriptase-polymerase chain reaction assay, we have determined the amount of specific mRNA for procollagen alpha(1) (III) (PIIIP) in the carbon tetrachloride (CCl(4)) model of liver fibrosis in rats. After a single week of CCl(4) application, the amount of PIIIP mRNA was increased approximately 10 times over the untreated control group and continued to increase to approximately 30 times after 7 weeks of intoxication. In this model substantial fibrosis was demonstrated by computer-aided morphometry after 5 to 7 weeks of treatment. Using recombinant murine N-terminal procollagen alpha(1) (III) propeptide (PIIINP), a novel sensitive immunoassay for the measurement of circulating PIIINP in rodent sera was established. An increase in PIIINP serum levels was observed after 5 to 7 weeks of CCl(4) intoxication. Our results suggest PIIIP gene expression is an early marker of tissue fibrosis. Early PIIIP gene expression is correlated with the extent of the subsequent fibrosis. PIIIP mRNA levels increase much earlier than conventional histological examination or PIIINP levels. PIIINP measurements with our new serum assay, on the other hand, are a good noninvasive marker of manifest fibrosis but are a poor marker of fibrogenesis.

Animals↗

Identification and expression of a novel type I procollagen C-proteinase enhancer protein gene from the glaucoma candidate region on 3q21-q24.

A novel human Type I procollagen C-proteinase enhancer protein-like gene, PCOLCE2, was identified by sequencing an EST in the primary open-angle glaucoma (POAG) region on 3q21. The total cDNA encoded a 415-amino-acid protein that has 43% identity to the Type I procollagen C-proteinase enhancer protein (PCOLCE1). PCOLCE2 contains two CUB domains, which are thought to be involved in protein-protein interactions, and an NTR module. PCOLCE2 message is expressed in the trabecular meshwork, lungs, heart, brain, liver, skeletal muscle, kidney, pancreas, and placenta as a 2-kb message. PCOLCE2, a 52-kDa protein, is expressed in the trabecular meshwork. A novel gene, PCOLCE2, has been identified and characterized. Based upon its homology with collagen-binding proteins, its expression in the trabecular meshwork, and its chromosome location, PCOLCE2 is a candidate gene for GLC1C. However, no coding sequence mutations were detected in PCOLCE2 in a POAG patient from the GLC1C family.

Animals↗

mRNA assessment for procollagen production in women with genuine stress urinary incontinence.

The aim of the study was to examine changes in the levels of mRNA for procollagen type I and III in women with or without genuine stress incontinence (GSI). The study was performed in the 2nd Department of Obstetrics and Gynecology of University of Athens. Sixty-eight women participated in the study and they were divided in two groups. We did not find statistically significant difference between the two groups of patients in relation to the amount of mRNA of procollagen type I and III (p>0.05), but the quantity of collagen type I and III was significantly reduced in patients with stress incontinence (p<0.05). The possible cause for the reduction in the amount of collagen in women with GSI could be attributed to either a disturbance in the translation of mRNA to protein (collagen) or increased catabolism of collagen by its collagenase.

Adult↗

Type III procollagen and collagen in skin.

A form of collagen, containing three alpha chains of type III, can be extracted from foetal calf, calf and rat skin under physiological conditions. This native collagen was purified by DEAE-cellulose chromatography and then was analysed by polyacrylamide gel electrophoresis which showed it consisted of several high molecular weight components, the size of gamma components and larger species. Prior reduction in dithiothreitol dissociated these large polymers into two components: the minor one migrated between the alpha1 (I) and alpha2 chains while the predominant one migrated between the alpha and beta chains. These two monomers were isolated by CM-cellulose chromatography. The minor one, which eluted between the alpha1 and alpha2 chains, had a molecular weight of approx. 95 000; its amino acid composition was similar to that of alpha1(III). The major one eluted in the alpha1 region and had a molecular weight of approx. 120 000; its amino acid composition, while similar to that of the alpha1(III) chain, differed in detail, and it is presumed to be a pro-alpha1(III) chain. Following pepsin digestion, the native collagen remained as a disulfide-bonded trimer which dissociated into only one component, a1(III), when denatured in dithiothreitol. These results suggest that the original, extracted protein consisted primarily ofa precursor form of type III collagen. This procollagen did not polymerize when heated at 37 degrees C and did not form the usual segment long spacing aggregates under suitable conditions. It was not modified by incubation with a purified procollagen peptidase preparation. This appears to be the first example of the isolation of type III (pro)collagen by extractive methods, without resorting to tissue digestion by proteolytic enzymes.

Amino Acids↗

Mast cells regulate procollagen I (alpha 1) production by bronchial fibroblasts derived from subjects with asthma through IL-4/IL-4 delta 2 ratio.

BACKGROUND: Asthma is characterized by inflammation and remodeling. Mast cells are generally increased in bronchial mucosa of subjects with asthma. These cells release a wide variety of cytokines and mediators that have the capacity to stimulate other resident cells such as smooth muscle cells and fibroblasts. OBJECTIVE: This study was designed to evaluate whether mast cells modulate collagen production by bronchial fibroblasts isolated from subjects with asthma and normal subjects through cytokine production. METHODS: Human mast cells were cocultured for 72 hours with primary bronchial fibroblasts isolated from bronchial biopsies of subjects with mild asthma and normal controls. Procollagen I (alpha1), IL-4Ralpha, IL-13Ralpha1, and IL-13Ralpha2 gene expression by bronchial fibroblasts and IL-4 and IL-4delta2 gene expression by mast cells were quantified by real-time RT-PCR. IL-4 production was also measured by ELISA in culture supernatants. RESULTS: Procollagen I (alpha1) gene expression by fibroblasts from subjects with asthma was significantly higher compared with cells from normal controls when cocultured with mast cells. Mast cells expressed IL-4 isoform and IL-4delta2, an alternative splice variant of IL-4. Coculture significantly increased the expression of IL-4 but not IL-4delta2 by mast cells when they were cultured with fibroblasts from subjects with asthma compared with cells from normal controls. Neutralization of IL-4 abrogated collagen mRNA expression. There was no significant change in IL-4Ralpha or IL-13Ralpha1. However, IL-13Ralpha2 gene expression was significantly reduced in fibroblasts from subjects with asthma. CONCLUSION: These results suggest that inflammatory process may regulate airway remodelling through crosstalk between inflammatory and structural cells. Targeting this crosstalk may have therapeutic application. CLINICAL IMPLICATIONS: Understanding mechanisms that govern airway remodeling and collagen deposition in asthma is a step toward therapeutic management of this disease. In this work, we found that mast cell-fibroblast crosstalk may be a potential future target to control some aspects of airway remodeling.

Alternative Splicing↗

Increase in serum 7S domain of type IV collagen and N-terminal propeptide of type III procollagen levels with normal serum transaminase levels after long-term oral administration of Tegaful-Uracil.

To evaluate whether oral administration of Tegaful-Uracil (UFT(R)), a biochemical modulator of 5-fluorouracil that contains tegafur and uracil, can induce hepatic fibrosis, serum 7S domain of type IV collagen and N-terminal propeptide of type III procollagen levels were measured in 63 UFT(R)-treated, 38 tegafur-treated and 40 untreated patients. Serum transaminase and bilirubin levels were normal in almost all patients. Serum levels of 7S collagen and type III propeptide increased in 25 and 17% of the UFT(R)-treated patients, respectively, although a majority of tegafur-treated and untreated patients showed no increase in these markers. The patients with the elevated levels demonstrated mild or moderate hepatic fibrosis without necroinflammation in the liver. Both serum levels decreased markedly after the discontinuation of UFT(R). These findings suggest that long-term oral administration of UFT(R) can induce hepatic fibrosis without the elevation of serum transaminase levels and necroinflammation in the liver, and serum 7S collagen and type III procollagen are of diagnostic value for UFT(R)-induced hepatotoxicity.

Journal Article↗

Intermediates in the limited proteolytic conversion of procollagen to collagen.

The conversion of chick bone procollagen to collagen proceeds in a stepwise fashion to produce a limited number of intermediates. Initial proteolytic cleavages remove NH2-terminal nonhelical extensions and yield an intermediate which remains disulfide-bonded via COOH-terminal extensions. Subsequent stepwise scission of one or two chains of the triple-stranded molecule in its COOH-terminal domain produces intermediates which can only be distinguished after dissociation of the noncovalently bonded alpha chains. A final cleavage in this region produces the collagen molecule and a disulfide-bonded triple-stranded fragment which represents the COOH-terminal domain. In all likelihood the endopeptidases which effect cleavage in the NH2- and COOH-terminal regions differ. More than two enzymes may be required for conversion of procollagen to collagen if the nonhelical domains are not released in an en bloc fashion.

Animals↗

Inhibitors of procollagen C-terminal proteinase block gastrulation and spicule elongation in the sea urchin embryo.

In the sea urchin embryo, inhibition of collagen processing and deposition affects both gastrulation and embryonic skeleton (spicule) formation. It has been found that cell-free extracts of gastrula-stage embryos of Strongylocentrotus purpuratus contain a procollagen C-terminal proteinase (PCP) activity. A rationally designed non-peptidic organic hydroxamate, which is a potent and specific inhibitor of human recombinant PCP (FG-HL1), inhibited both the sea urchin PCP as well as purified chick embryo tendon PCP. In the sea urchin embryo, FG-HL1 inhibited gastrulation and blocked spicule elongation, but not spicule nucleation. A related compound with a terminal carboxylate rather than a hydroxamate (FG-HL2) did not inhibit either chick PCP or sea urchin PCP activity in a procollagen-cleavage assay. However, FG-HL2 did block spicule elongation without affecting spicule nucleation or gastrulation. Neither compound was toxic, because their effects were reversible on removal. It was shown that the inhibition of gastrulation and spicule elongation were independent of tissue specification events, because both the endoderm specific marker Endo1 and the primary mesenchyme cell specific marker SM50 were expressed in embryos treated with FG-HL1 and FG-HL2. These results suggest that disruption of the fibrillar collagen deposition in the blastocoele blocks the cell movements of gastrulation and may disrupt the positional information contained within the extracellular matrix, which is necessary for spicule formation.

Animals↗

Metalloproteinase activity secreted by fibrogenic cells in the processing of prolysyl oxidase. Potential role of procollagen C-proteinase.

Lysyl oxidase is secreted from fibrogenic cells as a 50-kDa proenzyme that is proteolytically processed to the mature enzyme in the extracellular space. To characterize the secreted proteinase activity, a truncated, recombinant form of lysyl oxidase was prepared as a proteinase substrate containing the sequence of the propeptide cleavage region. The processing proteinase activity secreted by cultured fibrogenic cells resists inhibitors of serine or aspartyl proteinases as well as tissue inhibitor of matrix metalloproteinases-2 (MMP-2) but is completely inhibited by metal ion chelators. Known metalloproteinases were tested for their activity toward this substrate. Carboxyl-terminal procollagen proteinase (C-proteinase), MMP-2, and conditioned fibrogenic cell culture medium cleave the lysyl oxidase substrate to the size of the mature enzyme. The NH2-terminal sequence generated by arterial smooth muscle conditioned medium and the C-proteinase but not by MMP-2, i.e. Asp-Asp-Pro-Tyr, was identical to that previously identified in mature lysyl oxidase isolated from connective tissue. The C-proteinase activity against the model substrate was inhibited by a synthetic oligopeptide mimic of the cleavage sequence (Ac-Met-Val-Gly-Asp-Asp-Pro-Tyr-Asn-amide), whereas this peptide also inhibited the generation of lysyl oxidase activity in the medium of fetal rat lung fibroblasts in culture. In toto, these results identify a secreted metalloproteinase activity participating in the activation of prolysyl oxidase, identify inhibitors of the processing activity, and implicate procollagen C-proteinase in this role.

Amino Acid Sequence↗

Bone morphogenetic protein-1 (BMP-1). Identification of the minimal domain structure for procollagen C-proteinase activity.

Bone morphogenetic protein-1 (BMP-1) is a shorter spliced variant of mammalian tolloid (mTld), both of which cleave the C-propeptides of type I procollagen during the synthesis of extracellular matrix collagen fibrils. The fact that BMP-1 and mTld both exhibit procollagen C-proteinase (PCP) activity and that BMP-1 is the smaller variant might indicate that BMP-1 comprises the minimal required sequences for PCP activity. BMP-1 comprises a metalloproteinase domain, three CUB domains, and an epidermal growth factor (EGF)-like domain, which is located between the second and third CUB (complement components C1r/C1s, the sea urchin protein Uegf, and BMP-1) domains. In this study we showed the following. 1) The CUB1 domain is required for secretion of the molecule. Domain swapping experiments, in which CUB1 and other CUB domains were interchanged, resulted in retention of the proteins by cells. Therefore, CUB1 and its location immediately adjacent to the metalloproteinase domain are essential for secretion of the protein. 2) Mutants lacking the EGF-like and CUB3 domains exhibited full C-proteinase activity. In contrast, mutants lacking the CUB2 domain were poor C-proteinases. 3) Further studies showed that Glu-483 on the beta4-beta5 loop of CUB2 is essential for C-proteinase activity of BMP-1. In conclusion, the study showed that the minimal domain structure for PCP activity is considerably shorter than expected and comprises the metalloproteinase domain and the CUB1 and CUB2 domains of BMP-1.

Blotting, Western↗