Type Vi Collagen Promotes Cellular Adhesion And Survival
Cell Biology
Howell S J; Doane K J
Molecular Biology of the Cell
1997
1997-11
Journal Article or Conference Abstract Publication
n/a
Functional Interaction Between Beta(1) Integrins And Collagens May Prevent Apoptosis During Avian Corneal Stromal Development
Cell Biology
Howell S J; Doane K J
Molecular Biology of the Cell
1996
1996-12
Journal Article or Conference Abstract Publication
n/a
Identification and functional characterization of two type VI collagen receptors, alpha 3 beta 1 integrin and NG2, during avian corneal stromal development.
Animals; Chick Embryo; Fibroblasts/metabolism; Cell Movement/physiology; Immunoblotting; Integrins/*metabolism; Fluorescent Antibody Technique; Cell Culture Techniques; Extracellular Matrix/metabolism; Antigens/*metabolism; Cell Polarity/physiology; Cell Size/physiology; Collagen/*metabolism; Corneal Stroma/*embryology/*metabolism; Integrin alpha3beta1; Proteoglycans/*metabolism; Receptors; Indirect; Laminin/*metabolism
PURPOSE: The development and maintenance of extracellular matrix architecture in the corneal stroma is associated with abundant type VI collagen deposition. This collagen has been implicated in mediating both cell-matrix and matrix-matrix interactions. Although corneal fibroblasts spread extensively on this collagen, its role in corneal development has not been elucidated. METHODS: To clarify the role of this collagen, two type VI collagen receptors were studied during corneal development using immunochemical techniques: alpha 3 beta 1 integrin and an integral membrane proteoglycan, NG2. RESULTS: At embryonic day 6, these receptors were present in a diffuse pattern on cells within the cornea and juxtacorneal regions, indicating a migratory phenotype. At embryonic day 14, when the stroma is fully differentiated, alpha 3 and NG2 were localized in a punctate pattern on a subset of corneal fibroblasts, whereas beta 1 was more ubiquitously expressed. Colocalization of NG2 and type VI collagen indicated that this collagen was present and punctate in its organization was associated with NG2-positive cells. Immunochemical analyses at embryonic days 5 and 14 revealed alpha 3 and beta 1 at 155 kDa and 120 kDa, respectively, and demonstrated that these subunits were interacting to form a heterodimer. NG2 was present with a core protein of 330 kDa and an intact proteoglycan of approximately 600 kDa, and analysis of stromal lysates indicated a chondroitin sulfate-containing proteoglycan. Matrix-receptor cross-linking demonstrated the interaction of beta 1 and NG2 in periocular mesenchyme cells and corneal fibroblasts with type VI collagen, whereas only a subset of cells expressed alpha 3, indicating the presence of another beta 1 integrin. No variations between in vivo and in vitro expression of either alpha 3 beta 1 or NG2 were observed. CONCLUSIONS: These data indicate that two receptors for type VI collagen, alpha 3 beta 1 and NG2, are present during corneal stromal development, with a functional interaction of these receptors with type VI collagen. These interactions may play a role in corneal cell migration, development, and maintenance of corneal architecture.
Doane K J; Howell S J; Birk D E
Investigative ophthalmology & visual science
1998
1998-02
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Type VI collagen increases cell survival and prevents anti-beta 1 integrin-mediated apoptosis.
Animals; Antibodies; Apoptosis/*drug effects/physiology; Cell Nucleus/drug effects/metabolism; Cell Survival/drug effects/physiology; Cells; Chick Embryo; Collagen/*pharmacology; Cornea/drug effects/embryology/ultrastructure; Culture Media/chemistry/pharmacology; Cultured; DNA Fragmentation/drug effects; Extracellular Matrix/physiology; Eye/drug effects/embryology/ultrastructure; Fibroblasts/drug effects/metabolism/ultrastructure; Genetic Techniques; Integrins/immunology; Monoclonal/*drug effects/pharmacology
Cell-matrix interactions are important in the development of the avian cornea. Type VI collagen is present within the periocular mesenchyme prior to the migration of cells into the corneal stroma and is abundant in the mature stroma. Whether the interaction of cells with type VI collagen is essential for cellular survival in the cornea is not known. In the present study, we examined the interaction of corneal cells with type VI collagen in vitro to determine if it can increase cell proliferation and decrease apoptosis. In vivo analysis demonstrated that apoptosis occurs in the periocular region during early stages of avian corneal development, but in fully mature corneas apoptosis only occurs in the corneal epithelium and not in the stroma. In vitro analysis examined the importance of beta 1 integrin interactions with type VI collagen in mature corneal fibroblasts and the precursor cells. Using an anti-beta 1 integrin blocking antibody, CSAT, integrin/matrix interactions were disrupted. Results indicated that viability of both corneal fibroblasts and periocular mesenchyme cells was greater on type VI collagen than on type I collagen or BSA-blocked glass. In addition, less apoptosis was observed for both cell types on type VI collagen when beta 1 integrin–matrix interactions were disrupted. These data indicated that these cells require intact beta 1 interactions with type I collagen and with BSA-coated glass controls to remain viable. Thus, type VI collagen may play a role in the rescue of corneal cells from anti-beta 1 integrin-induced apoptosis by increasing cell survival, probably via a non-beta 1 integrin-dependent mechanism.
Howell S J; Doane K J
Experimental cell research
1998
1998-05
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1006/excr.1998.4051" target="_blank" rel="noreferrer noopener">10.1006/excr.1998.4051</a>