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Biomedical subjects

J Bonaventure

Publications and source records attributed to J Bonaventure.

At least 19 recordsLinked to original sources
PubMed1992

Type II collagen defect in two sibs with the Goldblatt syndrome, a chondrodysplasia with dentinogenesis imperfecta, and joint laxity.

We report on a syndrome of spondylo-epimetaphyseal dysplasia, dentinogenesis imperfecta, and ligamentous hyperextensibility in two sibs born to nonconsanguineous parents. This chondrodysplasia was characterized by severe shortness of stature and an osteoporosis without fractures. Electron microscopic examination of the cartilage documented large vacuoles of dilated rough endoplasmic reticulum within the cytoplasm of chondrocytes. Gel electrophoresis of pepsin-soluble collagen extracted from cartilage demonstrated the presence of type II collagen chains with an abnormal mobility. Prolyl and lysyl hydroxylations were slightly increased. The abnormal molecules melted at a higher temperature than the normal ones. CNBr peptide mapping of type II collagen showed an altered electrophoretic migration of peptides CB 11, CB 8, and CB 10,5 whereas CB 9,7 looked normal. In addition, two small non-collagenous proteins isolated from cartilage were not found in an age-matched control individual but were detected in a normal newborn infant. The quantitation of proline-labelled collagen synthesized by dermal fibroblasts demonstrated a 50% reduction of total collagen. This decrease essentially affected the amount of extracellular type I collagen, which was secreted less efficiently than in control cells. Nevertheless, type I collagen chains behaved normally on 5% polyacrylamide gels. The reduced mRNA levels of alpha 1I and alpha 2I chains might reflect either a transcriptional defect or a decreased stability of mRNA transcripts. We suggest that the association of both pathological chondrocytes producing altered collagen type II and decreased synthesis of type I could be responsible for this peculiar phenotype. The overmodification of alpha 1II CNBr peptides is consistent with the presence of a single-base substitution in the COL2A1 gene. Whether there is a direct causal relationship between the type II collagen defect and the underexpression of type I collagen will require clarification.

Abnormalities, Multiple↗
PubMed1992

Transforming growth factor-beta 1 (TGF-beta 1) up-regulation of collagen type II in primary cultures of rabbit articular chondrocytes (RAC) involves increased mRNA levels without affecting mRNA stability and procollagen processing.

The effect of transforming growth factor-beta 1 (TGF-beta 1) on collagen biosynthesis was investigated in confluent primary monolayer cultures of rabbit articular chondrocytes (RAC). Exposure to TGF-beta (0.1, 1, and 10 ng/ml) in serum-free medium caused a dose- and time-dependent stimulation of collagen biosynthesis associated with an increase of steady-state levels of procollagen type II mRNA. Elevation of the mRNA steady-state did not result from a stabilization of the transcript, as shown by measure of the mRNA half-life. Electrophoresis (SDS-PAGE) showed that TGF-beta stimulates the synthesis of most collagen isotypes, including type II, without qualitative change in their distribution. Moreover, pulse-chase experiments revealed that TGF-beta did not affect the processing rate of type II procollagen. TGF-beta slightly stimulated the production of prostaglandin E2 (PGE2), which could in turn exert an inhibition on collagen synthesis. However, addition of indomethacin to block prostaglandin synthesis did not further enhance the TGF-beta-induced stimulation of collagen production, suggesting that this mediator was not implicated in the effect. Moreover, TGF-beta increased steady-state levels of procollagen type II, I, and III mRNAs even in the presence of indomethacin. Despite these increased mRNA levels, only the production of type II collagen was significantly augmented, suggesting that type I procollagen mRNA was not fully translated. In addition, the TGF-beta-induced stimulation of collagen synthesis was observed whenever ascorbic acid is added or not in the culture medium. In conclusion, TGF-beta, which is present in great amount in bone and cartilage, can increase the collagen production of cultured RAC and might therefore play a role in the early events of cartilage repair, such as those observed in osteoarthritis.

Animals↗
PubMed1992

A dominant mutation in the COL1A1 gene that substitutes glycine for valine causes recurrent lethal osteogenesis imperfecta.

Type I collagen chains of a proband from a family with recurrent lethal osteogenesis imperfecta (OI) migrated as a doublet when submitted to gel electrophoresis. Cyanogen bromide (CNBr) peptide mapping demonstrated that the post-translational over-modifications were initiated in alpha 1ICB7. Chemical cleavage of cDNA-RNA heteroduplexes identified a mismatch in the alpha 1I cDNA; this mismatch was subsequently confirmed by sequencing a 249-bp fragment amplified by the polymerase chain reaction. A G to T transition in the second base of the first codon of exon 41 resulted in the substitution of glycine 802 by valine. This mutation impaired collagen secretion by dermal fibroblasts. The over-modified chains were retained intracellularly and melted at a lower temperature than normal chains. Collagen molecules synthesized by parental fibroblasts had a normal electrophoretic mobility, but hybridization of genomic DNA with allele-specific oligonucleotides revealed the presence of the mutant allele in the mother's leukocytes. The mutation was not detected in her fibroblasts consistent with the protein data. These results support the hypothesis that somatic and germ-line mosaicism in the phenotypically normal mother explain the recurrence of OI.

Alleles↗
PubMed1992

Effect of transforming growth factor-beta 1 (TGF-beta 1) on matrix synthesis by monolayer cultures of rabbit articular chondrocytes during the dedifferentiation process.

Since transforming growth factor-beta (TGF-beta) has been shown earlier to induce the chondrocyte phenotype in embryonic rat mesenchymal cells with production of cartilage-specific type II collagen and proteoglycans, it was of interest to determine whether the factor could also influence the differentiation state of articular chondrocytes maintained in monolayer culture. Using rabbit articular chondrocytes (RAC) in primary and passaged cultures, we demonstrate that the loss of the phenotype accompanying the subculture was not significantly influenced by the presence of TGF-beta. The factor exerted an inhibitory effect on collagen synthesis in a 6-day exposure of primary cultures whereas it stimulated that production throughout the subsequent passages. Steady-state levels of mRNAs encoding type I, II, and III procollagens were correlated with the amounts of cognate proteins produced, suggesting that both inhibition and stimulation were exerted at a transcriptional level. The pattern of proteoglycans produced in primary culture, essentially chondroitin sulfate-containing molecules, was altered by the subculture-induced RAC dedifferentiation, as shown by decrease in chondroitin sulfate formation and progressive appearance of hyaluronic acid. Contrasting with its effect on collagen synthesis, TGF-beta did not significantly change the proteoglycan production of RAC in our conditions whenever it was added at the beginning of the primary cultures or in the subsequent passages. Altogether, our data indicate that the effect of TGF-beta on RAC collagen synthesis depends on whether they are fully differentiated. Moreover, the data show that the factor does not prevent the loss of RAC phenotype but rather contributes to the dedifferentiation process since it exerts differential effects on the major components of extracellular matrix, collagen, and proteoglycans.

Animals↗
PubMed1992

Linkage studies of four fibrillar collagen genes in three pedigrees with Larsen-like syndrome.

We report seven children from three families who had a set of common clinical features suggestive of Larsen-like syndrome, including unusual facies, bilateral dislocations of the knees and elbows, club foot, and short stature. All of the patients originated from the island of La Réunion in the Indian Ocean. The occurrence of several affected sibs in these families and the large number of consanguineous marriages on this island are consistent with autosomal recessive inheritance of the disease. Based on this hypothesis, the pedigrees were used for linkage analysis in a candidate gene assay. Lod score calculations in a pairwise study with four different fibrillar collagen genes, COL1A1, COL1A2, COL3A1, and COL5A2, allowed us to exclude these genes as the mutant loci. Supporting this, electrophoretic analysis of collagens derived from fibroblast cultures failed to show defective molecules. We conclude that this syndrome is not a collagen disorder.

Abnormalities, Multiple↗
PubMed1991

Dominant mutations in familial lethal and severe osteogenesis imperfecta.

Four families presenting with familial osteogenesis imperfecta (OI) have been studied: 2 with the lethal type II and 2 with the severe type III form. Fibroblasts of the patients, all issue from non-consanguineous parents, produced normal and abnormal alpha(I) chains. These heterozygous mutations differentiate the recurrent forms from homozygous mutations characteristic of autosomal recessive forms. Although the identity of the mutations could not be determined, such recurrence of autosomal dominant OI is probably the result of germinal mosaicism in one of the parents. Biochemical results were consistent with a somatic mosaicism in the father's fibroblasts in one family. Moreover, our studies show that not only OI type II but also severe OI type III can arise from gonadal mosaicism. We discuss the importance of such a phenomenon for genetic counseling.

Abortion, Induced↗
PubMed1991

Morphological and biochemical studies of a mouse mutant (fro/fro) with bone fragility.

The mutation fragilitas ossium (fro) was discovered in a random-bred stock of mice during an experiment aimed at detecting recessive lethal mutations after treatment of the postmeiotic germ cells of male mice with tris (1-aziridinyl)phosphine sulphide. The affected mice were moderately runted and had deformities in all four limbs. The radiological and histological findings indicate that the mutant is similar to human osteogenesis imperfecta. The ash content of long bones was lower in the mutant. A defect of type I collagen could not be detected. The electrophoretic patterns of alpha bands of type I and V collagen and CB derived peptides of type I collagen from bone and skin showed no abnormalities. The total collagen synthesis and secretion in cultures of dermal fibroblasts, as well as the gel electrophoresis of procollagen and collagen chains synthesized, and of their CB peptides, were the same as those found in the controls. The percentage of type I and type V collagen synthesized was similar; that of type III was lower in the mutants. Bone osteonectin was found to be decreased by 30% and bone sialoprotein by 5%. The mRNA level for osteonectin was decreased in the fibroblasts of the mutant by about 50%. Whether the defective expression of the osteonectin in fro/fro mice is due to a mutation in the gene itself or its regulatory site(s), or is secondary to other factors remains to be established. The fro/fro mouse may represent a model for some forms of human bone fragility without collagen abnormalities.

Animals↗
PubMed1990

Modulation of sulfated proteoglycan synthesis and collagen gene expression by chondrocytes grown in the presence of bFGF alone or combined with IGF1.

Prepubertal rabbit epiphyseal chondrocytes were grown in high density primary culture for 3 d. They were then incubated for 3 additional d in serum-free culture medium to which bFGF (1-50 ng/ml) was added. During the last 24 h incubation period, either IGF1 (1-80 ng/ml) or Insulin (1-5 micrograms/ml) was added to the culture medium. Chondrocyte DNA was significantly augmented with the increasing concentration of bFGF used, thus confirming its mitogenic effect on chondrocytes. On the other hand, bFGF was also shown to modulate the phenotypic expression of the chondrocytes. The 35S-sulfate incorporation into newly synthesized proteoglycans by the cultured cells decreased in a dose-dependent manner with bFGF concentration used. In addition, chondrocyte collagen gene expression was also shown to be modulated by bFGF. Total RNA extracted from the cultured cells was analyzed by dot blot and Northern blot with cDNA probes encoding for alpha 1 II and alpha 1 I procollagen chains. A significant lower level of type II collagen mRNA, the marker of chondrocytic phenotype, was observed when cells were grown in the presence of bFGF while the level of type I mRNA remained unchanged. When IGF1 or a high concentration of insulin was added to the cells during the last 24 h of incubation with bFGF, sulfated proteoglycan synthesis, as well as collagen type II mRNA level, were significantly stimulated when compared with chondrocytes incubated with bFGF alone. In conclusion, in the present experimental conditions, bFGF appears to be a growth promoting agent for chondrocytes in vitro with dedifferentiating action on chondrocyte phenotype. IGF1 or insulin used at a high concentration can prevent the dedifferentiating effect of bFGF without inhibiting its stimulating effect on chondrocyte DNA synthesis.

Animals↗
PubMed1989

A new lethal brittle bone syndrome with increased amount of type V collagen in a patient.

A new lethal brittle bone disease is described in three patients with slender long bones, thin ribs, hypomineralized calvaria, and normal facial appearance. In spite of several limb fractures this syndrome can be differentiated from the lethal forms of osteogenesis imperfecta and is better related to the thin-bone group of lethal dysplasias. Biochemical investigation of collagen from one of the patients by the use of gel electrophoresis and high-pressure liquid chromatography analyses failed to demonstrate any evident defect in the structure of type I collagen chains. Nevertheless collagen extractability from the dermis was altered owing to an increase in the proportion of acid-soluble material. Tritium-proline labeling of cultured fibroblasts confirmed the reduction in total collagen synthesis. This was attributed to a lower type I and type III amount whereas type V collagen level was markedly increased in the cell layer. RNA analysis of the three collagen types with the appropriate cDNA probes confirmed the protein data. Electron microscopic examination of bone and skin showed morphologically abnormal fibroblasts and osteoblasts with an abundant distended rough endoplasmic reticulum and an altered plasma membrane. Unexpected thin fibrils with a banding pattern and surrounding the type I fibrils were observed. They might represent type V collagen. We suggest that, in this patient, the moderate decrease in type I collagen amount is insufficient to account for the radiological findings and that type V collagen overproduction could play a role in the bone brittleness by interfering with the process of mineralization.

Bone Diseases, Developmental↗
PubMed1989

Localization of gamma-glutamyl-phosphate residues to the alpha 2CB3-5 peptide of type I chicken bone collagen.

alpha 2(I) chains of chicken bone collagen were isolated and purified. Analyses confirmed previous studies that the alpha 2(I) chains contained gamma-glutamyl phosphate residues. Sodium borohydride reduction of the gamma-glutamyl phosphate residues of the CaCl2 extracted and purified alpha 2(I) chains and subsequent CNBr cleavage showed that most of the gamma-glutamyl phosphate groups were located on the alpha 2CB3-5 peptides of the type I collagen molecule, suggesting a specific function for these phosphorylated residues. The reported linkage of the Ser(P) containing phosphoproteins of dentin to the alpha 2CB4 regions of collagen may indicate different biological functions for these two different, protein-bound organic phosphate residues.

Amino Acids↗
PubMed1988

Effect of relaxin on the phenotype of collagens synthesized by cultured rabbit chondrocytes.

The effect of porcine relaxin on rabbit articular and growth plate chondrocytes in primary culture was investigated by measurement of total collagen production and analysis of the phenotypes of newly synthesized collagen chains. A 24-h treatment of monolayer articular and multilayer growth plate chondrocytes with 2 micrograms per ml relaxin had no effect on total DNA and did not significantly modify the amount of [3H]proline-labelled collagen chains secreted by the cells. However, polyacrylamide gel electrophoresis demonstrated relevant modifications in relaxin treated chondrocytes. A significant increase was observed in the proportion of type III collagen and in the intensity of the band corresponding to alpha 2I chains. Two-dimensional peptide mapping of CNBr-cleaved molecules indicated that the band that was identified as alpha 1II on monodimensional gels contained a significant proportion of alpha 1I collagen chains, as demonstrated by the presence of alpha 1I cyanogen bromide-digested peptides. The intensity of this band was increased by relaxin treatment. Furthermore, total RNA analysis by slot blot and Northern blot techniques showed a dose-dependent stimulation of alpha 1I and alpha 1III mRNA levels after incubation with increased relaxin concentrations, but no change in the amount of alpha 1II mRNA. These results suggested that when added to cartilage cells in vitro, relaxin modulated the expression of type I, type II and type III collagen genes by amplifying the dedifferentiation process.

Animals↗
PubMed1988

Interleukin-1 alpha modulates collagen gene expression in cultured synovial cells.

The effects of porcine interleukin-1 (IL-1) alpha on collagen production were studied in cultured human rheumatoid synovial cells. Addition of 0.05-5 ng of IL-1/ml into the cultures resulted in a dose-dependent decreased rate of collagen released into the medium over 24 h. To determine whether this inhibition was due to secondary action of prostaglandin E2 (PGE2) secreted in response to IL-1, cultures were incubated in presence of various inhibitors of arachidonate metabolism. Depending on the cell strains, these inhibitors were able to suppress or diminish the effect of IL-1, suggesting that PGE2 is involved in the mechanism. Depression of collagen production caused by IL-1 mainly affected type I collagen and therefore led to a change in the type I/type III collagen ratio in the extracellular medium. Steady-state levels of mRNA for types I and III procollagens were estimated by dot-blot hybridization and compared with the amounts of respective collagens produced in the same cultures. IL-1 generally increased procollagen type I mRNA, but to a variable extent, as did indomethacin (Indo). Depending on the cell strain, the combination of indo and IL-1 could elevate the mRNA level of type I procollagen compared with Indo alone. These results did not correlate with the production rate of collagen in the medium, which was diminished by exposure to IL-1. The level of mRNA for collagen type III was not greatly changed by incubation with IL-1, and a better correlation was generally observed with the amount of type III collagen found in the medium. These data suggest that an additional control mechanism at translational or post-translational level must exist, counterbalancing the stimulatory effect of IL-1 on collagen mRNA transcription. It is likely that IL-1 could modulate the production of collagen in synovial cells by an interplay of different mechanisms, some of them limiting the effect of primary elevation of the steady-state mRNA level.

Bucladesine↗
PubMed1988

[Effect of growth hormone on the differentiation of chondrocytes from prepuberal rabbits in serum-free culture and on the radioimmunologic activity of Sm-C/IGF1 measured in the culture medium].

This study concerns the immunoreactive somatomedin C secretion by prepubertal rabbit epiphyseal chondrocytes cultured in a defined serum-free medium. In such culture conditions, chondrocytes mainly synthesized Type II collagen (80% of total collagen) during 10 days. A small amount of Type I collagen was also found with a significant (p less than 0.05) higher level during the period of cell multiplication (6.4 +/- 1.5%) than when cells reached confluency (0.9 +/- 0.2%). During the 10 days of culture without serum and without hormone added, a Sm-C/IGF1 activity was measured by RIA at a mean level of 30 +/- 5 mU/ml/10 micrograms DNA. This value was significantly higher (p less than 0.001) than in the medium not incubated with the cells (1.7 +/- 0.9 mU/ml). When hGH was added to the culture medium during the period of cell division, the level of Sm-C/IGF1 activity was significantly elevated at 39 +/- 4 mU/ml/10 micrograms DNA (p less than 0.05) and at 55 +/- 3 mU/ml/10 micrograms DNA (p less than 0.001) with 50 ng/ml and 100 ng/ml hGH concentrations respectively. On the contrary, no difference was observed at confluency in treated and non treated cells.

Animals↗
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↗
PubMed1986

[Antenatal forms of osteogenesis imperfecta. Classification trial].

A classification of the different types of osteogenesis imperfecta is proposed. There are 3 main groups: the lethal type, the severe type and the so-called regressive type, with a more favorable course. This classification was established to allow for a more precise definition of the prognosis at the time of birth, or even in utero when diagnosis is made by ultrasonography. It should also allow for better classification of the data obtained by the study of the molecular collagen. This project is different from Sillence's one by the exclusion of type II B lethal types, which are often compatible with survival. In view of the frequent occurrence of a dominant mutation in the type II A, the more generally accepted recessive transmission is discussed.

Diagnosis, Differential↗