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N L Charbonneau

Publications and source records attributed to N L Charbonneau.

4 recordsLinked to original sources
PubMed2001

Assembly of epithelial cell fibrillins.

Fibrillins are large structural macromolecules that are components of connective tissue microfibrils. Fibrillin microfibrils have been found in association with basement membranes, where microfibrils appear to insert directly into the lamina densa. It is unknown whether fibrillins are limited to these sites of microfibril insertion or are present throughout the lamina densa. In this study, electron microscopic immunolocalization demonstrated the presence of fibrillin-1 throughout the lamina densa in the dermal-- epidermal junction. In order to investigate whether fibrillin microfibrils might be present in the lamina densa, epithelial cell cultures (WISH, HaCaT, and primary keratinocytes) were analyzed by immunofluorescence, immunoblotting, and extraction of microfibrils followed by rotary shadowing electron microscopy and compared to mesenchymal cell cultures (dermal fibroblasts and MG63 osteosarcoma). In contrast to mesenchymal cells, which elaborate a fibrillin fibril network, epithelial cells primarily deposit fibrillin into the extracellular matrix in a nonfibrillar form. Coculture experiments using human epithelial cells and mouse fibroblasts implicated the cells themselves in the assembly of fibrillin. The importance of the cell in this process was further underscored by novel data demonstrating that keratinocytes selectively secrete fibrillin-1 into the matrix and not into the medium and can differentiate between fibrillin-1 and fibrillin-2.

3T3 Cells↗
PubMed1997

The fate of cartilage oligomeric matrix protein is determined by the cell type in the case of a novel mutation in pseudoachondroplasia.

We have identified a novel missense mutation in a pseudoachondroplasia (PSACH) patient in one of the type III repeats of cartilage oligomeric matrix protein (COMP). Enlarged lamellar rough endoplasmic reticulum vesicles were shown to contain accumulated COMP along with type IX collagen, a cartilage-specific component. COMP was secreted and assembled normally into the extracellular matrix of tendon, demonstrating that the accumulation of COMP in chondrocytes was a cell-specific phenomenon. We believe that the intracellular storage of COMP causes a nonspecific aggregation of cartilage-specific molecules and results in a cartilage matrix deficient in required structural components leading to impaired cartilage growth and maintenance. These data support a common pathogenetic mechanism behind two clinically related chondrodysplasias, PSACH and multiple epiphyseal dysplasia.

Achondroplasia↗
PubMed1993

Fibrillin binds calcium and is coded by cDNAs that reveal a multidomain structure and alternatively spliced exons at the 5' end.

Fibrillin is an important structural protein of the extracellular matrix. It is a large cysteine-rich glycoprotein with extensive intrachain disulfide bonds, likely contributed by multiple EGF-like repeats. We have previously published 6.9 kb of FBN1 cDNA sequence. FBN1 cDNA clones that extend the sequence 3089 bp in the 5' direction are described in this report. The deduced primary structure suggests that fibrillin is composed of multiple domains. The most predominant feature is the presence of 43 calcium binding EGF-like repeats. We demonstrate here that fibrillin molecules bind calcium. In addition, three alternatively spliced exons at the 5' end are described. Analysis of 5.8 kb of surrounding genomic sequence revealed a 1.8-kb CpG island spanning the alternatively spliced exons and the next downstream exon. Since FBN1 is the gene responsible for Marfan syndrome, the information presented here will be useful in identifying new mutations and in understanding the function of fibrillin in the pathogenesis of the disease.

Alternative Splicing↗