The Carboxylpropeptide of Type I Procollagen in Skin Fibrillogenesis

Previous studies suggested that the antinopropeptide of type 1 procollagen may initiate fibril formation. The purpose of this investigation was to study the location of the carboxypropeptide of type 1 procollagen during collagen fibrillogenesis. Chick embryonic and posthatching skin specimens were studied by immunofluorescence and immunoelectron microscopy and by immunoblotting with antibodies against the amino and carboxypropeptide of type 1 procollagen. The carboxylpropeptide was demonstrated at the surface of collagen fibrils, 20–40nm in diameter (10-day embryos) and in fibrils, 40–65nm (21-day embryos). In addition, the carboxylpropeptide was found at the cell surface and free in the ground substance. The aminopropeptide was only seen in fibrils, 20–30nm in diameter, as previously reported. Ratios of pN-collagen/pC-collagen increased from 16 days embryonic to 3 and 9 days postembryonic skins. This study suggests that both pN-collagen (antinopropeptide plus collagen) arid pC-collagen (carboxylpropetide plus collagen) participate in fibrillogenesis

Immunochemistry of Elastotic Material in Sun-Damaged Skin

The nature of elastotic material in sun-damaged human skin was investigated by indirect immunofluorescence. Antibodies were used against the following components of the dermis: type I and type VI collagens, aminopropeptide of type I and type III procollagens, fibronectin, elastin, microfibrillar proteins, and basement membrane represented by the 7S domain of type IV collagen, laminin, and nidogen. The elastotic material exhibited marked fluorescence for elastin and microfibrillar proteins which codistributed with fibronectin. The presence of type I and VI collagens and procollagen type III were demonstrated to a lesser extent within the elastotic material. These results suggest that solar elastosis is primarily derived from elastic fibers and not from preexisting or newly synthesized collagens

Culturing Keratinocytes and Fibroblasts in a Three-Dimensional Mesh Results in Epidermal Differentiation and Formation of a Basal Lamina-Anchoring Zone

The purpose of this study was to characterize an in vitro co-culture model in which fibroblasts grown in a three-dimensional nylon mesh were recombined with human keratinocytes. The cultures were kept for 3 and 5 weeks and then processed for electron microscopy. Keratinocytes showed reconstruction of an epidermis consisting of a basal layer with hemidesmosome's, a stratified epithelium with tonofilament's and desmosomes, a granular layer with keratinosomes and keratohyaline granules, and a transitional stratum corneum. Anchoring filaments, lamina densa, anchoring fibrils, bundles of elastin-associated microfibrils (diameters 10 nm) and fine collagen fibrils were formed. Collagen fibrils near the epidermis were much thinner than those in the lower levels.The present study shows that the dermal model containing metabolically active fibroblasts in their natural environment will support epidermal morphogenesis and differentiation including the formation of a basal lamina and anchoring zone

Initiation of skin basement membrane formation at the epidermo-dermal interface involves assembly of laminins through binding to cell membrane receptors

To study the mechanism of basement membrane formation, we determined by immunochemistry temporal and spatial expression of laminin-5 (Ln-5), laminin-1 (Ln-1) and their integrin receptors during early skin morphogenesis. A 3-dimensional skin culture was used that allows the study of the sequential molecular events of basement membrane formation at the epidermodermal interface. During early anchorage of keratinocytes to the extracellular matrix there is expression of Ln-5, BP-230 antigen and &#945;3, &#946;1 integrin subunits. During epidermal stratification and prior to the formation of the lamina densa there is assembly of Ln-5, Ln-1, collagen IV and nidogen accompanied by keratinocyte basal clustering of &#945;2, &#945;3, &#945;6, &#946;1, and &#946;4 integrin subunits. The assembly pattern of Ln-1 and Ln-5 can be disturbed with functional antibodies against the &#946;1 (AIIB2) and &#945;6 (GoH3) integrin subunits. Ln-1 assembly can also be disturbed with antibodies against its E8 domain and by competitive inhibition with a synthetic peptide (AG-73) derived from its G-4 domain. Quantitative RT-PCR showed that the dermis contributes about 80% of the laminin &#947;1 chain mRNA while 20% is produced by the epidermis which emphasizes its dual tissue origin and the major contribution of the mesenchyma in laminin production. The laminin &#947;2 chain mRNA, present in Ln-5, was mostly of epidermal origin. This study presents evidence that during the initiation of basement membrane formation, laminins bind to keratinocyte plasma membrane receptors and thus may serve as nucleation sites for further polymerization of these compounds by a self-assembly process.</p

Collagen: The Great Biological Architect

Dr. Fleischmajer is Chairman and a professor of the Department of Dermatology of the Mount Sinai School of Medicine, New York City. Born in Buenos Aires, Argentina, Dr. Fleischmajer earned his B.A. degree from Manuel Belgrano and his M.D. degree from the University of Buenos Aires. A United States citizen, Dr. Fleischmajer served as a resident of a number of hospitals, including New York University Hospital and Bellevue Hospital, both in New York City, and Philadelphia\u27s Skin and Cancer Hospital. Dr. Fleischmajer has taught as an instructor at New York University and as a visiting lecturer at the University of Philadelphia. From 1968-79, Dr. Fleischmajer served as a professor of Medicine and the Director of the Division of Dermatology at the Hahnemann Medical College in Philadelphia, until his move to Mount Sinai School of Medicine. Dr. Fleischmajer\u27 s awards include the Henry Silver Award in 1963 and a number of gold and silver awards for scientific exhibits. He currently serves as chief editor of Progress in Diseases of the Skin, a position he has held since 1980. He was chief editor of the International Journal of Dermatology for almost 15 years. Dr. Fleischmajer has been a reviewer for more than ten scientific journals and has written several books. The doctor\u27s memberships include the American Medical Association, the American Academy of Dermatology, the American Dermatological Association, the American Association of Pathologists, and the American Association for the Advancement of Science. His Work: Dr. Fleischmajer has concentrated his research efforts on the biochemistry of skin, particularly its lipid metabolism and protein structure. His work has led him to an investigation of the role of collagen in the development of skin disorders such as scleroderma. (This information was taken from the Distinguished Scientist Lecture Series Program 1988-1989).https://digitalcommons.bard.edu/dsls_1988_1989/1001/thumbnail.jp

Identification of Collagen Fibrils in Scleroderma Skin

Skin from early and late stages of scleroderma has been shown to contain large amounts of thin (30–40nm diameter) collagen fibrils that may be present in bundles or intermingled with large diameter fibrils (90–120 nm). The nature of these fibrils is unknown. Skin biopsies were obtained from involved areas of nine patients with progressive systemic sclerosis (PSS), one case of generalized morphea, one case of morphea, and six normal controls. Intact skin was analyzed by immunoelectron microscopy (IEM), while extracts were subjected to sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE), Western immunoblotting, radioimmunoassay (RIA), and enzyme-linked immunosorbent assay (ELISA). Fine fibrils 20–40nm in diameter in the mid to lower dermis of scleroderma skin were labeled with anti- bodies directed against the aminopropeptide (AP) of type III procollagen. Antibodies directed against the AP of type I procollagen labelled fine fibrils in the lower dermis. Larger fibrils (80–120 nm)did not label. pNα1 (III) was found to be present in both normal and scleroderma skin. Extracts of scleroderma skin contained 2.5 times the amount of pN (III) collagen and 3.0 times the amount of fibronectin as did extracts of normal skin. The data indicate that the increase in thin fibrils in scleroderma skin is most likely due to an increase in type III collagen, which retains the AP at its surface