Intervertebral disc disease is one of the most common musculoskeletal disorders. A number of environmental and anthropometric risk factors may contribute to it, and recent reports have suggested the importance of genetic factors as well. The COL9A2 gene, which codes for one of the polypeptide chains of collagen IX that is expressed in the intervertebral disc, was screened for sequence variations in individuals with intervertebral disc disease. The analysis identified a putative disease-causing sequence variation that converted a codon for glutamine to one for tryptophan in six out of the 157 individuals but in none of 174 controls. The tryptophan allele cosegregated with the disease phenotype in the four families studied, giving a lod score (logarithm of odds ratio) for linkage of 4.5, and subsequent linkage disequilibrium analysis conditional on linkage gave an additional lod score of 7.1.

These data suggest that non-enzymatic glycosylation of matrix proteins, and specifically collagen, may modify arterial elasticity in diabetic patients with coronary artery disease.

Biochemical and molecular genetic studies have recently suggested that mutations in the gene coding for fibrillin on chromosome 15 result in Marfan syndrome. To our knowledge, only one mutation in the fibrillin gene has been published. Here we report the results of screening 20 unrelated MES patients for mutations in fibrillin cDNA by the singlestrand conformation polymorphism technique. We found two mutations, both of which appear in the heterozygote form and code for a shortened fibrillin polypeptide. The first mutation is a large in-frame deletion of 366 bases of the fibrillin mRNA, shown to result in a truncated but secreted polypeptide found in the fibroblast culture of the patient. The second mutation is a G-to-A transition resulting in the substitution of a stop codon for a tryptophan codon and thus predicting the premature termination of the polypeptide chain. We screened 60 other, unrelated MFS patients for these mutations as well as for the previously reported mutation (arginine-239 to proline) and found none of the three mutations in any of these patients. These data suggest that most MFS families carry their own distinct mutation.The Marfan syndrome (MFS) is an autosomal dominant connective-tissue disorder characterized by cardiovascular, ocular, and skeletal manifestations (1). By the random linkage approach, the MFS locus was assigned to the long arm of chromosome 15 in three Finnish families (2). Later, the linkage was confirmed in families from diverse ethnic backgrounds, and the locus was more precisely localized to the immediate vicinity of the polymorphic marker DISSI (3-5). To date, linkage analyses of chromosome 15 markers in families from different populations have not revealed any evidence for genetic heterogeneity underlying MFS (3-5).Independent simultaneous immunohistochemical analyses demonstrated a nearly constant deficiency of fibrillin, an extracellular protein (6), in skin sections and cultured fibroblasts from MFS patients (7). Subsequently, the fibrillin cDNA was cloned (8) and the corresponding locus was mapped by in situ hybridization to chromosome 15q21.1 (9, 10), in the vicinity of the marker DJSSI. The MATERIALS AND METHODSPatients. The material consisted of fibroblast lines established from skin biopsies of 20 unrelated MFS patients from Finland and the United Kingdom and blood samples of these and 41 additional MFS patients from Belgium, Finland, the Netherlands, Switzerland, the United Kingdom, and the United States, including patients both with and without family history of MFS. All the samples were taken in accordance with the Helsinki Declaration. The diagnoses were made by using the criteria established by Beighton et al. (12).The patient R.H. was a 48-year-old man with cardiovascular, eye, and skeletal symptoms and signs of MFS. He was a member of a three-generation English pedigree none of whom have ectopia lentis. The propositus' mother had peripheral retinal degeneration and retinal detachment. A brother and sister of the propositus had severe mitral va...

No abstract

No abstract

Conversion from procollagen to collagen is a specific process that is a requirement for proper alignment of collagen molecules to form functional fibers. This process is catalyzed by at least three structurally and functionally distinct enzymes cleaving collagen types I-III. The cleavage processes possibly taking place in the more recently discovered collagen types are not known to any extent at this time. Two amino-terminal proteinases, one cleaving type I and type II procollagens and the other cleaving type III procollagen, have been purified close to homogeneity, and the more unspecific activity of carboxy-terminal proteinase has been isolated from several tissues. In our experimental model, however, cleavage of the carboxy-terminal propeptides of types I and III procollagen is differently affected by lysine. This suggests the presence of at least two distinct enzymes for the removal of carboxyl-terminal propeptides. The regulation of the reaction process from procollagen to collagen is not well known at present. The importance of the phenomenon in terms of fibril formation, however, is demonstrated by several elegant studies in vitro; and certain genetic disorders in which this process is defective demonstrate the significance in vivo. Moreover, the factors shown to effect the cleavage process may be potentially beneficial in the treatment of the pathological processes with abnormal collagen accumulation such as fibrosis. In this paper we briefly review the current knowledge of the converting enzymes, including some very recent findings of our laboratory as well as the evidence presented for the biological significance of the conversion process.

Deposition of types I and III collagen is a typical feature in the development of pulmonary fibrosis. We assessed the propeptides of these procollagens as prognostic markers in 18 patients with fibrosing alveolitis. We analyzed the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal propeptide of type I procollagen (PICP) from samples of bronchoalveolar lavage fluid (BALF) and serum, and also estimated their concentrations in epithelial lining fluid (ELF) by the urea method. The level of PIIINP in serum (p < 0.05), BALF (p < 0.05), and ELF (p < 0.05), and the levels of PICP in BALF (p < 0.001) and ELF (p < 0.001) but not in serum, were significantly increased in the patients with fibrosing alveolitis as compared with 17 controls who had been investigated for minor respiratory symptoms. In the BALF and ELF of patients with fibrosing alveolitis, PICP but not PIIINP had significant negative correlations with the specific diffusion coefficient for carbon monoxide (DLCO/ VA). The amino-terminal propeptide of type III procollagen and the carboxy-terminal propeptide of type I procollagen in BALF correlated significantly with one another. During the follow-up period of 6 yr, seven of the 18 patients with fibrosing alveolitis died of the disease, 3 others died of malignancy, and one patient died from an unknown cause. DLCO (p < 0.05) differed significantly between the surviving patients and those who died of fibrosing alveolitis, and detectable PIIINP in BALF predicted death from fibrosing alveolitis (p = 0.05). In conclusion, these results show that PIIINP in BALF, ELF, and serum, and PICP in BALF and ELF, are increased in patients with fibrosing alveolitis. A high level of PICP in BALF, and especially in ELF, suggests a chronic process and increased synthesis of type I collagen in the lungs, whereas PIIINP in BALF and ELF suggests active disease and a poor prognosis.

Several structural analogues of proline have been shown to be incorporated into proteins in place of proline. As a consequence, the proliferation of cells in culture and the extracellular deposition of collagen in animal systems are reduced. In this study, the effects of two proline analogues, cis-4-hydroxy-L-proline and L-azetidine-2-carboxylic acid, on the growth parameters and procollagen production by cultured normal human skin fibroblasts were examined. The results indicated that incubation of the cells with the analogues reduced the rate of fibroblast proliferation and lowered the plating efficiency. Further experiments demonstrated that fibroblasts in the presence of L-azetidine-2-carboxylic acid synthesized procollagen polypeptides which were not in a triple-helical conformation, as judged by limited pepsin proteolysis. Also, a significantly increased fraction of the newly synthesized collagenous peptides was in a dialyzable form, suggesting increased degradation of the nonhelical chains. The rate of translation of collagenous polypeptides and the preprocollagen messenger RNA activity in the cells were not affected by the analogues. The proline analogues thus appear to inhibit the production of procollagen on the posttranslational level by preventing the polypeptides from folding into a stable triple-helical conformation. The nonhelical polypeptides are then readily susceptible to proteolysis leading to reduced deposition of extracellular collagen fibers. Similar experiments were also performed with fibroblasts cultured from patients with active progressive systemic sclerosis. Quantitatively and qualitatively comparable inhibition of procollagen production by L-azetidine-2-carboxylic acid was noted with scleroderma cells as with control fibroblast cultures. The results suggest, therefore, that proline analogues may, in the future, prove useful in limiting excessive collagen deposition in scleroderma and other forms of dermal fibrosis.