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Type VIII collagen has a restricted distribution in specialized extracellular matrices
1Department of Biological Structure, University of Washington, Seattle 98195.
The Journal of Cell Biology
|August 1, 1988
Summary
Researchers developed a new antibody to study type VIII collagen, a protein found in specialized extracellular matrices like the eye and nervous system. This unusual collagen is synthesized as a discontinuous triple helix by proliferating cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Extracellular Matrix Research
Background:
- Type VIII collagen is a component of the extracellular matrix, but its synthesis and distribution are not fully understood.
- Previous studies suggested type VIII collagen is a short-chain collagen, but its precise structure and cellular origin remained unclear.
Purpose of the Study:
- To produce and characterize a monoclonal antibody (mAb) against type VIII collagen.
- To investigate the synthesis, structure, and tissue distribution of type VIII collagen.
Main Methods:
- Isolation of a pepsin-resistant triple helical domain of type VIII collagen.
- Production of monoclonal antibodies (mAbs) using the isolated domain.
- Biochemical characterization using competition ELISA and immunoblotting.
- Tissue immunofluorescence studies on bovine corneal endothelial cells and fetal calf tissues.
Main Results:
- A specific mAb was generated that recognized type VIII collagen but not types I-VI collagens.
- Subconfluent bovine corneal endothelial cells secreted a high molecular mass (125,000 Mr) component of type VIII collagen, appearing as a discontinuous triple helix.
- Confluent cells secreted a different collagenous component (60,000 Mr) that did not react with the anti-type VIII collagen antibody.
- Immunofluorescence revealed type VIII collagen deposited as fibrils in the extracellular matrix of corneal endothelial cells.
- In fetal calves, type VIII collagen was found in specific tissues, including ocular sclera, meninges, periosteum, perichondrium, and white matter, but absent from basement membranes and many other organs.
Conclusions:
- Type VIII collagen is synthesized as a discontinuous triple helical molecule, primarily by proliferating cells.
- This unusual collagen is a component of specialized extracellular matrices, particularly those derived from neural crest cells.
- The distribution pattern suggests a specific role in tissues requiring structural integrity and organization, such as the eye and nervous system.