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At least 793 records · Page 44Linked to original sources
PubMed1999

In vitro synthesis of type I collagen: quantification of carboxyterminal propeptide of procollagen type I versus tritiated proline incorporation.

Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen has been recently introduced to measure in vitro synthesis of type I collagen by osteoblasts and fibroblasts. However, it has not been assessed whether the equivalent results are obtained with this new assay and with tritiated proline incorporation to collagen protein. To this purpose, both methods were used to quantify synthesis of type I collagen in normal human osteoblast cultures to which fetal calf serum and human serum were added in order to stimulate protein synthesis. A positive correlation in the results obtained by both methods was obtained (r = 0.95, P = 0.0001). Given the technical advantages of detection of levels to carboxyterminal propeptide of type I procollagen, we consider that this is the technique of choice for the quantification of in vitro synthesis of type I collagen by normal human osteoblasts.

Aged↗
PubMed1997

Macrophage products inhibit human aortic smooth muscle cell proliferation and alter 1 alpha (I) procollagen expression.

While the role of the foam cell in early atherogenesis has been well characterized, much less is known about the interaction between infiltrating macrophages and medial smooth muscle cells (SMC) in chronic atherosclerosis. Our purpose was to determine the effects of soluble macrophage mediators on normal human aortic SMC proliferation and matrix expression. Human aortic SMC in subconfluent culture were exposed to supernatants from activated lipopolysaccharide (LPS) and nonactivated macrophages. SMC proliferation and type-I procollagen expression were determined. Both activated and nonactivated macrophage supernatants exhibited a potent growth inhibitory effect which became apparent at 48 hours. While nonactivated macrophage supernatant had no effect on procollagen expression, activated supernatant inhibited its expression. (33%; p < 0.05) These findings are consistent with the loss of medial SMC and matrix proteins associated with chronic atherosclerosis.

Aorta, Abdominal↗
PubMed1988

Impaired secretion of type III procollagen in Ehlers-Danlos syndrome type IV fibroblasts: correction of the defect by incubation at reduced temperature and demonstration of subtle alterations in the triple-helical region of the molecule.

The amount of type III procollagen secreted by fibroblasts from two patients with type IV Ehlers-Danlos syndrome is reduced to 25% and 20%, respectively, of that of control cells after incubation at 37 degrees C, but reverts to 70% and 110% when cells are incubated at 32 degrees C. The type III procollagen molecules secreted only at the lower temperature are of normal size but apparently contain different mutations which disrupt the triple-helical region and lower the thermal stability of the molecule. These data suggest that subtle mutations in the pro alpha 1(III)-chains produce Ehlers-Danlos syndrome type IV by disrupting the triple-helical region of the molecule, lowering its thermal stability, and thus impairing its secretion. At the lower temperature, stabilization of the defective molecules result in more efficient secretion. This approach may be useful for the characterization of other unstable collagens.

Cell Line↗
PubMed1982

Heterogeneity of the antigens related to the aminoterminal propeptide of type III procollagen in human serum.

Inhibition curves that are considerably less steep than the reference peptide curve are a constant finding when human serum samples are studied with the radioimmunoassay for the aminoterminal propeptide Col 1-3 of type III procollagen. This is due to the presence in the serum of three main peptide forms which differ in their antigenic properties and can be separated by gel filtration. Their molecular sizes are, respectively, larger than, equal to and smaller than the peptide Col 1-3. The proportions of these forms were different in a number of serum samples tested. An elevated value in the Col 1-3 radioimmunoassay need not reflect increased deposition of type III collagen in the liver, but could also be due to increased degradation of a newly-synthesized type III procollagen or degradation of a tissue form still containing the aminoterminal propeptide. This should be considered when interpreting elevated serum values.

Amino Acid Sequence↗
PubMed1984

N-terminal procollagen peptide and beta 2-microglobulin in synovial fluids from inflammatory and non-inflammatory joint diseases.

The concentrations of NH2-terminal procollagen peptide were determined radioimmunologically in synovial fluids from inflammatory and non-inflammatory joint diseases. The mean concentrations +/- SD were 1.39 +/- 0.77 and 1.13 +/- 0.63 mg/l and, hence, did not reveal significant differences. Compared with serum, peptide levels in synovial fluids are 10(3) times higher. No statistical correlation was found between procollagen peptide levels and the concentrations of beta 2-microglobulin, a suggested parameter of disease activity, and other established indicators (total protein, total and differential cell count) of inflammatory activity.

Arthritis↗
PubMed1986

Serum concentrations of laminin and aminoterminal propeptide of type III procollagen in relation to the portal venous pressure of fibrotic liver diseases.

In sera of patients with fibrotic liver diseases (n = 33) classified histologically into various degrees of liver fibrosis (n = 21) and cirrhosis (n = 12) the concentrations of the basement membrane protein laminin and of its pepsinresistant fragment P1 and of the N-terminal propeptide of type III procollagen were determined. The concentrations of both proteins were related to the portal venous pressure measured in these patients. Compared with the reference population (n = 146) the concentration of laminin increases from 1.04 U/ml (normal persons) to 1.69 +/- 0.46 U/ml in liver fibrotic and 2.58 +/- 0.87 U/ml in liver cirrhotic patients. Although the concentrations of the propeptide of type III procollagen increase also there exist only weak correlations between both connective tissue proteins in serum. Laminin is correlated highly positive with the portal venous pressure in cirrhotic subjects (r = 0.9206), the extent of laminin elevation reflects closely the degree of portal hypertension. Virtually all of the fibrotic patients having a laminin concentration within the reference range had a normal portal venous pressure. The data suggest laminin as a potentially useful parameter for monitoring the portal venous pressure in cirrhotic and severe fibrotic patients.

Female↗
PubMed1991

Collagen peptidase and type III procollagen peptide serum levels in chronic liver diseases.

The concentration of the N-terminal peptide of procollagen III and the activity of collagen peptidase (PZ-peptidase) were measured in sera from 92 patients with chronic liver disease. In patients with liver cirrhosis and chronic hepatitis with transformation of liver structure, high values were found for both variables compared with hepatoses and chronic hepatitis without transformation. The concentration of procollagen III peptide and the activity of collagen peptidase in serum increased with increasing degrees of fibrosis and, even more markedly, with increasing degrees of mesenchymal activity in the liver.

Adult↗
PubMed1984

Modulation of types I and III procollagen synthesis at various stages of arterial smooth muscle cell growth in vitro.

Collagen synthesis was monitored in cultures of rabbit arterial smooth muscle cells (SMC). Both the rate of collagen synthesis per cell and collagen synthesis as a percent of total protein synthesis were measured at specific intervals from 1 to 14 days after inoculation of smooth muscle cells. The proportions of types I and III collagen present in the conditioned incubation medium and in the cell layer were also examined. After inoculation the cells displayed population expansion typical of SMC in which growth slowed but did not cease after the cells attained confluence. Collagen synthesis rates, expressed as [14C]hydroxyproline per cell, were eight-fold higher in preconfluent cells. In these cultures collagen accounted for more than 20% of the newly synthesized, 14C-labeled protein present as trichloroacetic acid (TCA)-insoluble material in 24 h culture media. In post-confluent cultures, this percentage was reduced to about 7% of the total protein synthesized. Synthesis rates of both collagen and non-collagen protein decreased with increasing time after inoculation. However, the rate of decline of collagen synthesis was three times greater than that seen for non-collagen protein. Early cultures synthesized relatively more type I than type III procollagen. The type I to type III ratio was highest at day 3 and declined after that time to day 14. While the synthesis of both types decreased with increasing age, type I declined at a greater rate resulting in a predominance of type III procollagen secretion by older cultures. We conclude that protein synthesis in general and collagen synthesis in particular are quantitatively and qualitatively dependent upon the growth stage of SMC in vitro.

Animals↗
PubMed1985

Increased type I procollagen mRNA levels and in vitro protein synthesis in the baboon model of chronic alcoholic liver disease.

We have investigated the molecular mechanisms responsible for the histologic changes induced by ethanol in the baboon model of alcoholic liver disease. Eleven ethanol-fed baboons and their pair-fed controls had histology evaluated and RNA extracted from percutaneous liver biopsy specimens. In 6 of the ethanol-fed animals, fatty liver developed, but no significant differences were found when the RNA from the control and ethanol-fed livers was translated in the reticulocyte lysate system or analyzed with specific cDNA probes. Five of the baboons given ethanol, however, developed significant fibrosis. Molecular evaluation revealed that the RNA from these livers was more active in in vitro protein synthesis, and the type I procollagen mRNA content was significantly higher per microgram of liver RNA as determined by hybridization analysis (183% +/- 23% SEM of control, p less than 0.02). In addition, there were higher levels of albumin mRNA content in the livers of ethanol-fed baboons that developed fibrosis (180% +/- 21% SEM of control, p less than 0.05). There was no change, however, in the levels of beta-actin mRNA, a representative constitutive protein. These findings in the baboon model of alcoholic fibrosis show that ethanol consumption increases type I procollagen mRNA, which may foster fibrogenesis; increases albumin mRNA content without causing an increase in serum albumin; and induces no change in levels of beta-actin mRNA. These studies also show that percutaneous needle biopsy can supply sufficient tissue to evaluate molecular changes in human liver disease.

Actins↗
PubMed1989

Pleomorphism in type I collagen fibrils produced by persistence of the procollagen N-propeptide.

The assembly of type I collagen and type I pN-collagen was studied in vitro using a system for generating these molecules enzymatically from their immediate biosynthetic precursors. Collagen generated by C-proteinase digestion of pC-collagen formed D-periodically banded fibrils that were essentially cylindrical (i.e. circular in cross-section). In contrast, pN-collagen generated by C-proteinase digestion of procollagen formed thin, sheet-like structures that were axially D-periodic in longitudinal section, of varying lateral widths (up to several microns) and uniform in thickness (approximately 8 nm). Mixtures of collagen and pN-collagen assembled to form a variety of pleomorphic fibrils. With increasing pN-collagen content, fibril cross-sections were progressively distorted from circular to lobulated to thin and branched structures. Some of these structures were similar to fibrils observed in certain heritable disorders of connective tissue where N-terminal procollagen processing is defective. The observations are considered in terms of the hypothesis that the N-propeptides are preferentially located on the surface of a growing assembly. The implications for normal diameter control of collagen fibrils in vivo are discussed.

Collagen↗
PubMed1989

Transglutaminase-catalysed cross-linking: a potential mechanism for the interaction of fibrinogen, low density lipoprotein and arterial type III procollagen.

Bovine type III [3H]procollagen or its [125I]aminopropeptide were shown by chromatography under dissociating conditions to form very high molecular weight compounds with excess bovine fibrinogen after incubation with purified tissue transglutaminase, though none is formed with other major plasma proteins. Larger compounds of this type formed from fibrinogen or fibrin monomer can be separated by centrifugation and they are insoluble on washing with 1% SDS. Ultracentrifugation showed that a significant fraction of [3H]procollagen III forms a low density complex on incubation with transglutaminase plus excess IDL or LDL, but not HDL. SDS polyacrylamide gel electrophoresis showed that type III collagen [125I]aminopropeptide forms high molecular weight compounds after incubation with transglutaminase plus excess IDL or LDL but not with HDL. It is hypothesized that, in the presence of excessive concentrations of LDL and/or fibrinogen and of tissue transglutaminase, crosslinking reactions of the type demonstrated may interfere with normal injury-repair processes and stimulate the formation of atherosclerotic lesions in arteries.

Animals↗
PubMed1977

Procollagen and collagen produced by a teratocarcinoma-derived cell line, TSD4: evidence for a new molecular form of collagen.

Procollagen and collagen were isolated from the culture medium and cell layer of line TSD4 (obtained from mouse teratocarcinoma OTT6050). SDS-polyacrylamide gel electrophoresis of the highly purified procollagen fraction demonstrated that the fraction is composed of theta chains (150,000 daltons), pro alpha chains (130,000 daltons), and alpha chains (100,000 daltons). Limited pepsin digestion of this fraction yielded a single species of collagen molecules having a chain composition (alpha1)3, as did collagen isolated from the cell layer. Each alpha1 chain appears to be slightly larger than alpha1 chains from calf or human type I and type III collagen. Amino acid analysis and cyanogen bromide peptide profiles of pepsin-treated TSD4 collagen demonstrated significant differences from those of other collagens (II, III, IV) of the type alpha1(X)3, although similar to that of the alpha1 chain of type I collagen, [alpha1(1)]2alpha2. Taken together, acrylamide gel electrophoresis, amino acid composition, electron microscopy, and cyanogen bromide peptide analysis indicate that this material represents a new molecular species of collagen not previously characterized, probably related to [alpha1(I)]3.

Amino Acids↗
PubMed1983

Liver procollagen prolyl hydroxylase in Opisthorchis viverrini infected hamsters after praziquantel administration.

Infection of hamsters by the human liver fluke Opisthorchis viverrini elevated liver procollagen prolyl hydroxylase activity, reflecting increased collagen biosynthesis. The increase was proportional to the intensity of infection. However, the infected liver procollagen prolyl hydroxylase activity decreased after administration of praziquantel 300 mg kg-1 body weight, and approached normal levels two weeks after treatment. In the infected hamsters, praziquantel, at a curative dose, caused a transient increase in serum aminotransferase levels and a small but persistent rise in serum alkaline phosphatase. The drug, however, did not cause changes in these enzyme activities in the uninfected hamsters.

Alanine Transaminase↗
PubMed1988

Relative content of isoaccepting tRNAs for glycine and proline in avian tendon cells with different rates of procollagen synthesis.

The relative amounts of iso-tRNAsGly and iso-tRNAsPro existing in chick embryo tendon are indicative of a specialization of the tRNA population for collagen synthesis. These amounts are not modified (i) in primary avian tendon (PAT) cells in culture for which the procollagen production varies from about 10% of total protein synthesis to 60% and (ii) in tendons from immature chicks, which show a 3-fold decrease of procollagen production with increasing age. The characteristic tRNA pattern was not maintained in cells which had lost the ability to make high levels of collagen as observed in the cases of: (i) PAT cells reaching confluency; (ii) virus-transformed PAT cells and (iii) tendon from adult chick. Our data are consistent with the idea that tendon tRNA specialization for collagen synthesis is a differentiation feature independent of the expression level of the collagenic function but related to its maintenance.

Aging↗
PubMed1986

Abnormal procollagen synthesis in fibroblasts from three patients of the same family with a severe form of osteogenesis imperfecta (type III).

Dermal fibroblast cultures from three siblings with a severe form of osteogenesis imperfecta were established in order to analyze their procollagen and collagen synthesis. Cell strains from clinically normal consanguineous parents (first cousins), were also obtained for comparison. Total collagen production in culture media was diminished by 55% in the patients fibroblasts and to a lesser extent in the parents. This decrease was specific for collagenous proteins. From polyacrylamide gel electrophoresis, it appeared that the three children had not only the same defective secretion of pro alpha 1(I) molecules but that their pro alpha 1(I) migrated slightly faster than the parental and control counterparts. Analysis of secretion confirmed a reduced rate in procollagen synthesis and the absence of intracellular storage. Upon pepsin treatment, extracellular alpha 1(I) and alpha 2(I) chains were found in the expected ratio of 2:1 and migrated normally, suggesting that the altered mobility of pro alpha 1(I) chains was related to COOH or NH2 terminal propeptides. In agreement with the reduced type I collagen production, an increase in the alpha 1(III)/alpha 1(I) ratio was also detected. Furthermore, after a 2.5-h labelling followed by alkylation with iodoacetamide, free intracellular pro alpha 2(I) and alpha 1(I) chains were detected in the absence of reduction, consistent with an abnormal intracellular ratio of pro alpha 1(I)/pro alpha 2(I) that was measured after dithiothreitol reduction. Analysis of intracellular collagen chains from parental strains following a 4-h incubation demonstrated that pro alpha 1(I) appeared as a doublet, one band with normal mobility and a less intense band migrating faster and corresponding to the defective chain found in the patients. Absence of the abnormal molecules in culture media was related to the demonstration of a defective collagen secretion by parental fibroblasts. Correlation between these biochemical findings and clinical data strongly support a recessive inheritance of the disease that could be classified as a type III form of osteogenesis imperfecta. Patients would be homozygous for the same defective allele and the asymptomatic parents would most likely be heterozygous carriers of the mutation. Although the exact location of the alteration is not yet elucidated, a splicing mutation is suggested.

Adolescent↗
PubMed1992

Effect of insulin on serum amino-terminal propeptide of type III procollagen in non-insulin-dependent diabetes mellitus.

The effect of insulin on the serum levels of the amino-terminal propeptide of type III procollagen (PIIINP) was investigated in patients with non-insulin-dependent diabetes mellitus, whose disease was unsatisfactorily controlled by oral drugs. Before insulin therapy the PIIINP values of the patients (3.2 +/- 1.3 micrograms/l, n = 38) varied within the range of healthy subjects (3.1 +/- 0.6 micrograms/l, n = 50, NS). Insulin therapy (6-20 IU at bedtime plus the oral drugs) improved the glycemic control and increased the serum PIIINP during a 4 week (3.1 +/- 0.9 to 3.8 +/- 1.1 micrograms/l, P less than 0.01, n = 8) and an 8 week period (3.2 +/- 1.3 to 3.8 +/- 1.6 micrograms/l, P less than 0.001, n = 22). The values were still elevated after 6 months on insulin (3.5 +/- 1.5 to 4.0 +/- 1.7 micrograms/l, P less than 0.01, n = 12). Placebo-insulin did not alter the concentration of PIIINP (3.1 +/- 0.6 to 2.8 +/- 0.6 micrograms/l, NS, n = 8) whereas the glycemic control improved and body weight decreased. The PIIINP values correlated with fasting insulin before (r = 0.403, P less than 0.05, n = 30) and after the therapy (r = 0.452, P less than 0.001, n = 60). Insulin therapy, while correcting the hormone deficiency and restoring glucose and protein metabolism, seems to activate the synthesis of type III procollagen in patients with NIDDM. This may promote the atherosclerotic process.

Adult↗
PubMed1977

Inhibitory effects of tunicamycin on procollagen biosynthesis and secretion.

Chick embryo cells were briefly exposed to the antibiotic, tunicamycin. Pre-exposed cells, compared to control cultures, showed a severe, progressive inhibition of the incorporation of glucosamine and mannose into total cellular macromolecules. Inhibition of the incorporation of glycine, leucine and proline was also progressive but not as marked as for the carbohydrates. Cellular secretion of all macromolecules was severely impaired. while comparison of the procollagens showed no difference in their subunit size or in their degree of glycosylation; the intracellular content of procollagen polypeptides was similar for both types of cells. In vitro studies showed that tunicamycin selectively inhibited glucosamine, but not mannose, incorporation into macromolecules. The composite results indicate that tunicamycin effectively inhibits protein synthesis, protein glycosylation and protein secretion in chick embryo cells.

Animals↗