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Alterations in cartilage type-II procollagen and aggrecan contents in synovial fluid in equine osteochondrosis.

The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C-propeptide of cartilage type-II procollagen, which is released following the synthesis of this molecule, to analyse synovial fluids from equine tarsocrural joints with and without osteochondrosis. In young horses with osteochondrosis, there was a significant increase of C-propeptide of type-II procollagen accompanied by a decrease in the 846 and keratan sulfate epitopes. The results identify differential alterations in aggrecan and type-II collagen turnover in the cartilage matrix in young animals with osteochondrosis that may contribute to the pathological degeneration of articular cartilage in this disease.

Aggrecans↗

3,4-methylenedioxymethamphetamine ("Ecstasy") stimulates the expression of alpha1(I) procollagen mRNA in hepatic stellate cells.

3,4-Methylenedioxymethamphetamine, MDMA ("Ecstasy"), has been previously shown to produce cell necrosis and fibrosis in the liver. Our aim was to study the effect of MDMA on the type I collagen production by a cell line of hepatic stellate cells (HSC), the cell type mainly responsible for collagen synthesis in the liver. We demonstrated that MDMA increases alpha1(I) procollagen mRNA levels and that this increase correlates with glutathione depletion and enhanced hydrogen peroxide production by HSC. Pre-treatment with either glutathione monoethyl ester or deferoxamine prevents the MDMA-induced alpha1(I) procollagen mRNA expression, indicating oxidative stress to be a mediator of this effect. Lipid peroxidation was not detected in MDMA-treated cells and therefore does not seem to be involved in the pro-fibrogenic action of MDMA on HSC.

Antioxidants↗

Preferential expression of alternatively spliced mRNAs encoding type II procollagen with a cysteine-rich amino-propeptide in differentiating cartilage and nonchondrogenic tissues during early mouse development.

Type II procollagen mRNAs are alternatively spliced: type IIA mRNA contains an exon encoding a cysteine-rich domain in the amino-propeptide and type IIB mRNA lacks this exon. In mouse embryos between 9.5 and 13.5 days, type IIA mRNA was the major form of Col2a-1 transcript expressed in both prechondrogenic and nonchondrogenic tissues and type IIB mRNAs were present in small amounts. After 12.5 days, type IIB mRNA levels increased rapidly and finally exceeded type IIA mRNAs. Type IIB mRNAs became the major Col2a-1 transcript by 14.5 days, predominantly expressed in maturing chondrocytes. By 17.5 days type IIB mRNAs account for 80% of the Col2a-1 transcripts. Expression of type IIA mRNAs follows the change in the growth pattern of the cartilaginous model of the axial and appendicular skeleton and of the otic capsule and nasal septum. In nonchondrogenic tissues, type IIA mRNAs are more commonly expressed in epithelial structures of ectodermal and endodermal origin than in nonepithelial tissues. The switching of expression from type IIA to type IIB mRNA as major Col2a-1 transcript may be associated with the commitment of precursor cells to the chondrocyte lineage and sites of type IIA mRNA expression may mark regions of potential cartilage growth. The differential expression pattern of type IIA mRNAs therefore points to an association of type IIA procollagen with chondrocyte differentiation during cartilage growth and some function early in embryogenesis in the epithelial organization of nonchondrogenic tissues.

Alternative Splicing↗

Procollagen-derived biomarkers in malignant ascites of ovarian cancer. Independent prognosticators for progression-free interval and survival.

OBJECTIVE: Matrix formation is a hallmark of solid tumor biology. Circulating antigens of structural matrix proteins should reflect this fact, yet are subject to systemic variables. We propose that if measured regionally, in a cancer-induced extravascular fluid pool such as malignant ascites of ovarian cancer, the same antigens retain their conceptual advantage as surrogate markers for tumor biology. METHODS: In malignant ascites obtained at staging laparatomy of 35 women with ovarian cancer, the protein-normalized levels of the C-terminal propeptide of procollagen type I (pnPICP) and the N-terminal propeptide of procollagen type III (pnPIIINP) were determined. Using univariate and multivariate analysis, we examined these parameters, their (pnPIIINP/pnPICP) quotient, and clinical criteria (FIGO stage, age, residual tumor, histology, and tumor grade) for impact on progression-free interval and survival. RESULTS: The absolute level of pnPIIINP was the single most powerful independent factor impacting on survival, its P value being distinctly below (P = 0.0005 vs 0.003) and its risk ratio distinctly above (15 vs 2.5) residual tumor after debulking surgery. The relative level of pnPIIINP, i.e. (pnPIIINP / pnPICP), impacted on the likelihood of recurrence even more than residual tumor. By Kaplan-Meier analysis, cutoff values for the absolute or relative pnPIIINP level significantly discriminated patients with shortened survival or progression-free interval, respectively. CONCLUSIONS: Since malignant ovarian epithelium itself forms collagen type III, and since collagen type III is a solid-phase regulator of angiogenesis, we propose that ascitic pnPIIINP is a fluid-phase indicator for angiogenic activity in ovarian cancer and thus represents a tumor virulence index.

Age Factors↗

Liquid crystalline ordering of procollagen as a determinant of three-dimensional extracellular matrix architecture.

The precise molecular mechanisms that determine the three-dimensional architectures of tissues remain largely unknown. Within tissues rich in extracellular matrix, collagen fibrils are frequently arranged in a tissue-specific manner, as in certain liquid crystals. For example, the continuous twist between fibrils in compact bone osteons resembles a cholesteric mesophase, while in tendon, the regular, planar undulation, or "crimp", is akin to a precholesteric mesophase. Such analogies suggest that liquid crystalline organisation plays a role in the determination of tissue form, but it is hard to see how insoluble fibrils could spontaneously and specifically rearrange in this way. Collagen molecules, in dilute acid solution, are known to form nematic, precholesteric and cholesteric phases, but the relevance to physiological assembly mechanisms is unclear. In vivo, fibrillar collagens are synthesised in soluble precursor form, procollagens, with terminal propeptide extensions. Here, we show, by polarized light microscopy of highly concentrated (5-30 mg/ml) viscous drops, that procollagen molecules in physiological buffer conditions can also develop long-range nematic and precholesteric liquid crystalline ordering extending over 100 microm(2) domains, while remaining in true solution. These observations suggest the novel concept that supra-fibrillar tissue architecture is determined by the ability of soluble precursor molecules to form liquid crystalline arrays, prior to fibril assembly.

Animals↗

Spondyloepiphyseal dysplasia and precocious osteoarthritis in a family with an Arg75-->Cys mutation in the procollagen type II gene (COL2A1).

Direct sequencing of polymerase chain reaction (PCR)-amplified genomic DNA from a patient with spondyloepiphyseal dysplasia and precocious osteoarthritis revealed a single-base change in exon 11 of the type II procollagen gene (COL2A1), which produces an Arg-->Cys mutation in one allele. The proband is a member of a large Chilean kindred presenting with chondrodysplasia of the hips, knees, shoulders, elbows, and spine associated with severe, early-onset osteoarthritis. All affected individuals exhibit mildly short stature; in addition, five out of seven affected family members display shortened metacarpals or metatarsals. DNA from affected and unaffected family members was PCR-amplified and analysis of restriction digests of the products determined that the mutation segregated with the disease with a lod score of 2.2 at zero recombination. The mutation, which resides in the triple-helical region of type II procollagen at amino acid position 75, is the second example of an Arg-->Cys mutation in the COL2A1 gene in heritable cartilaginous disease and is the first example of a point mutation in the amino terminal region of the alpha 1(II) chain, that results in a spondyloepiphyseal dysplastic phenotype.

Adolescent↗

Serum levels of bone Gla protein (osteocalcin, BGP) and carboxyterminal propeptide of type I procollagen (PICP) in acromegaly: effects of long-term octreotide treatment.

We measured serum concentrations of bone Gla-protein (osteocalcin, BGP) and carboxyterminal propeptide of type I procollagen (PICP) in 14 patients with active acromegaly. Blood was collected at 0800 for measurement of bone Gla-protein (BGP), carboxyterminal propeptide of type I procollagen (PICP), and insulin-like growth factor I (IGF-I); growth hormone (GH) was then determined at 15-minute intervals for 3 hours and the integrated mean was calculated. The same protocol was repeated at regular intervals during treatment with the long-acting somatostatin analog, octreotide, 150-450 micrograms/day for 6-33 months (median 15). In a case-control analysis, serum BGP concentrations recorded in the acromegalic patients were significantly elevated (14.2 +/- 4.2 micrograms/liter versus 8.0 +/- 3.3 micrograms/liter, P < 0.001). Octreotide treatment induced a roughly parallel reduction in serum GH, IGF-I, and BGP. We found a significant positive correlation between BGP levels recorded before and during therapy and the logarithm of corresponding mean GH levels (r = 0.67, P < 0.001). Also IGF-I concentrations were positively correlated with BGP (r = 0.66, P < 0.001). On the other hand, PICP levels recorded in the acromegalics did not differ from control subjects (146 +/- 46 micrograms/liter versus 127 +/- 44 micrograms/liter, NS) and no correlation was found between either GH and PICP or IGF-I and PICP. To conclude, the present data are compatible with the view that GH and IGF-I play an important role in the control of BGP but not PICP production. It could be that BGP and PICP are submitted to different hormonal modulation.

Acromegaly↗

Evaluation of serum type III procollagen peptide as an exposure marker in retired coal workers.

Serum type III procollagen peptide (PIIIP), a degradation product of the type III collagen precursor, has been put forward as an exposure marker for mineral dust. We evaluated PIIIP levels as a marker of exposure to and effects of coal dust in retired coal miners (n = 104). To this end: (a) the individual cumulative dust exposure was calculated from job-exposure matrices, and (b) in addition to routine chest radiography (CR) of all miners according to the criteria of the International Labour Organisation (ILO), a subgroup (n = 46) was screened by high-resolution computed tomography (HRCT). Profusion score (CR and HRCT) tended to increase with cumulative dust exposure, even in the absence of CR evidence for pneumoconiosis (i.e. CR < or = 0/1, n = 35). In contrast to our previous findings in active miners, PIIIP levels were not increased in miners as compared with non-dust-exposed controls (n = 29), and no differences were observed between miners without (ILO = 0/0) and miners with coal workers' pneumoconiosis (CWP; ILO > or = 0/1). No trend in PIIIP versus pneumoconiosis stage was present, either by CR or by the more sensitive HRCT score. PIIIP was also unrelated to any lung function parameter (FEV1, FVC, impedance, diffusion capacity). Age, medication, medical history and smoking habits had no significant effect on PIIIP levels. In the miners with CWP (i.e. ILO > 0/0, n = 28) a significant negative correlation was present between PIIIP values and (log) cumulative dust exposure. This decrease in serum PIIIP levels with increasing cumulative exposure may be due to chronic adaptive changes in type III collagen deposition and/or breakdown. Other relations between exposure and PIIIP were not observed. In conclusion, the present findings do not support the use of serum type III procollagen peptide as a marker of exposure to and (early) interstitial or respiratory effects of coal dust.

Coal Mining↗

Aminoterminal extension peptides from type I procollagen normalize excessive collagen synthesis of scleroderma fibroblasts.

Fibroblasts derived from a skin biopsy of a patient with scleroderma in the sclerotic stage were shown to have a higher rate of DNA synthesis, and to synthesize more collagen than fibroblasts from a healthy control. The addition of procollagen peptides to the culture medium of scleroderma fibroblasts almost normalized the collagen synthesis. This observation indicates that the mechanism for the regulation of collagen synthesis by feed back inhibition of prollagen peptides is functioning in this disease. It is suggested that the level of biologically active procollagen peptides is lowered.

Collagen↗

The aminoterminal-type-III procollagen peptide and proteoglycans in serum and synovial fluid of patients with rheumatoid arthritis or reactive arthritis.

The concentrations of aminoterminal-type-III procollagen (procollagen N-) peptide, and of proteoglycans were measured in knee-joint synovial fluid and serum from patients with rheumatoid arthritis or reactive arthritis. All synovial fluids contained large amounts of intact propeptide. The synovial fluid: serum propeptide ratios were high, suggesting local propeptide liberation. A correlation was demonstrated between the propeptide concentration in synovial fluid and in serum. In rheumatoid arthritis, the propeptide concentration in synovial fluid was related to local inflammatory activity, and the serum concentration was correlated with the presence of nonspecific markers of inflammation. The presence of smaller propeptide fragments in synovial fluid indicated that some degradation occurred locally. The local metabolic changes were most prominent in patients with joint erosions. Patients with nonerosive rheumatoid arthritis and reactive arthritis had similar synovial fluid propeptide concentrations. The proteoglycan content of synovial fluid was inversely related to the degree of joint destruction, and was highest in patients with reactive arthritis. No correlation was observed between the concentrations of propeptide and proteoglycan in synovial fluid. Intraarticular glucocorticoid injection reduced the levels of propeptide and proteoglycan in synovial fluid.

Adult↗

Types I and III procollagen extension peptides in serum respond to fracture in humans.

Markers of types I and III collagen turnover were measured in serial blood samples in 16 patients with a Colles' fracture. The collagen markers were the carboxy-terminal extension peptide of type I procollagen (PICP) and the amino-terminal extension peptide of type III procollagen (PIIINP). Significant increases were found of PIIINP within 1 week and of PICP within 2 weeks. This sequential appearance of PIIINP and PICP was found to be in agreement with the appearance of types III and I collagen during early fracture healing as demonstrated in previous animal experimental studies. PICP had levelled off after 9 months, whereas PIIINP remained elevated. Osteocalcin, a serum marker of osteoblast activity, increased within 1 week and levelled off after 9 months. Correlations between the change in osteocalcin and those in PICP and PIIINP, respectively, were weak. These new biochemical markers may prove relevant as non-invasive markers of normal and pathological fracture healing in humans.

Adult↗

Prolonged exercise causes an increase in the activity of galactosylhydroxylysyl glucosyltransferase and in the concentration of type III procollagen aminopropeptide in human serum.

The effect of prolonged heavy physical exercise on serum galactosylhydroxylysyl glucosyltransferase activity (S-GGT) and serum type III procollagen aminoterminal propeptide (S-Pro(III)-N-P) concentration was studied in healthy male long-distance runners. S-GGT increased gradually by about 70% (p less than 0.01) during a competitive 24-h run, and a rising trend was also observed in S-Pro(III)-N-P. After the termination of the run S-GGT was normalized in two days, but the increase in S-Pro(III)-N-P continued up to one day after the race, reaching nearly 40% (p less than 0.005). The alterations in S-GGT and S-Pro(III)-N-P showed no significant correlation with S-CK, S-LDH or the distance run. The most likely explanation for the increases in S-GGT and S-Pro(III)-N-P is that prolonged heavy exercise injures the collagen-synthesizing cells of the connective tissue, leading to a short-term increase in type III procollagen production.

Adult↗

Localization of type III procollagen aminopeptide antigenicity in hepatocytes from cirrhotic human liver.

Immunolocalization of type III procollagen (pro III) in normal and cirrhotic human liver was studied using rabbit antiserum specific for bovine type III procollagen aminopeptide. The material examined was deparaffinized, trypsin-treated hepatic tissue sections from 28 autopsy cases, including 19 cirrhotic and 9 normal liver donors. Immunostaining, performed by the unlabeled peroxidase-antiperoxidase antibody technique demonstrated that extracellular matrices corresponding to perisinusoidal reticulin, collagen in periportal areas, and blood vessel walls were the common sites of pro III antigenicity in both normal and cirrhotic liver. Moreover, in the cirrhotic liver, the fibrous septa of pseudolobules, and cytoplasm of hepatocytes and sinusoidal cells were positive when stained for pro III peptide. The differential counts of pro III positive cells in cirrhotic liver, however, revealed that the average ratio of these hepatocytes to sinusoidal cells was 25 to 1, indicating complete dominance of hepatocytes with respect to stainability for pro III peptide compared to sinusoidal cells. In hepatocellular carcinomas coexisting with cirrhosis, neoplastic cells also displayed pro III antigenicity. These data suggest that hepatocytes of cirrhotic liver and hepatocellular carcinoma cells play a significant role in type III collagen synthesis in vivo.

Adult↗

Synthesis of full-length cDNAs from partially purified human procollagen mRNAs.

Partially purified human procollagen mRNAs have been copied using reverse transcriptase from avian myeloblastosis virus. Under standard conditions, using a high deoxynucleotide concentration, only incomplete cDNAs corresponding to one-fifth to one-half of the template could be synthesized. Addition of a ribonuclease inhibitor from human placenta in the reaction mixture allowed the synthesis of full-length cDNA copies from extremely long procollagen mRNA.

Avian Myeloblastosis Virus↗

Evaluation of hepatic fibrosis by serum proline and amino-terminal type III procollagen peptide levels in alcoholic patients.

In patients with alcoholic liver disease, serum proline and amino-terminal type III procollagen peptide levels were evaluated as a marker of hepatic fibrosis. Thirty-one patients with alcoholic liver disease (2 with nonspecific change, 3 with alcoholic hepatitis, 17 with hepatic fibrosis without cirrhosis, and 9 with cirrhosis) and 15 controls were investigated. Hepatic fibrosis was estimated in each liver biopsy specimen by morphometric analysis, and the ratio of fibrotic change to total area (AREA-F) was calculated by morphometric analysis. In patients with hepatic fibrosis, serum proline levels and routine liver function tests were not significantly correlated to AREA-F value, while serum peptide levels showed a significant positive correlation to AREA-F value (r = 0.733, P less than 0.001). These results suggest that the determination of serum amino-terminal type III procollagen peptide level may serve as a good marker for the diagnosis of liver fibrosis in the alcoholic.

Adult↗

Localization of human type II procollagen gene (COL2A1) to chromosome 12.

DNA was prepared from 39 human-mouse somatic cell hybrid lines, and mouse and human parental cell lines. The DNA was digested to completion with EcoRI and Southern filters were prepared. These filters were hybridized at high stringency conditions to the human genomic subclone phHCol(II) A which corresponds to the human alpha 1(type II) procollagen gene (COL2A1). The mouse DNA yielded a single band at greater than 10 kb, whereas the human DNA had the expected single band at 4.8kb. Analyses of these human-mouse cell hybrids demonstrated that the human alpha 1(type II) procollagen gene segregates with chromosome 12.

Chromosome Mapping↗

Decreased procollagen production in cultured fibroblasts from patients with Lowe's syndrome.

The oculo-cerebro-renal syndrome described by Lowe is a catastrophic disease in children characterized by progressive eye, central nervous system and kidney degeneration. We determined procollagen production in cultured skin fibroblasts originating from patients with Lowe's syndrome as well as normal individuals after incubation of cells with [14C]proline for 1,4 and 20 h. Using [14C]hydroxyproline formation, in relation to cell protein or DNA, as an index of procollagen production, we found that cultured cells from patients synthesized collagenous protein at a substantially reduced level. This decrease in synthesis in cultured fibroblasts from patients could not be accounted for by differences in the specific radioactivity of the free intracellular proline; moreover, it could not be attributed to differences in the kinetics of growth between normal and affected cell lines. The degree of hydroxylation of proline residues in collagen was the same in both normal and affected cells.

Cells, Cultured↗

Caenorhabditis elegans dpy-5 is a cuticle procollagen processed by a proprotein convertase.

Genetic analysis of the nematode Caenorhabditis elegans reveals that all dpy-5 alleles are dominant suppressors of bli-4 blistering. Molecular cloning of dpy-5 establishes that it encodes a cuticle procollagen, defects in which are responsible for the short-body, dumpy phenotype. The null mutation, e907 removes the entire coding region, whereas the dpy-5 reference allele, e61, contains a nonsense substitution. RT-PCR analysis and a dpy-5::gfp fusion show that dpy-5 is expressed only in hypodermal cells at all post-embryonic life-cycle stages. Variable expression of dpy-5 in V lineage-derived seam cells suggests an alternative regulatory mechanism in these cells. The dpy-5 gene product contains an Arg-X-X-Arg cleavage motif that could be recognized by a proprotein convertase, such as BLI-4. Mutation of this site cause a dominant dumpy phenotype suggesting Dpy-5 procollagen requires processing for normal cuticle production.

Amino Acid Sequence↗