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In vitro Synthesis of Native, Fibrous Long Spacing and Segmental Long Spacing Collagen
Published on: September 20, 2012
Three novel collagen VI chains, alpha4(VI), alpha5(VI), and alpha6(VI)
Jamie Fitzgerald1, Cathleen Rich, Fiona H Zhou
1Department of Orthopaedics and Rehabilitation, Oregon Health and Science University, Portland, OR 97239, USA. fitzgerj@ohsu.edu
The Journal of Biological Chemistry
|April 11, 2008
Summary
Three new collagen VI genes (COL6A4, COL6A5, COL6A6) were identified, expanding the collagen VI family. Only the alpha4(VI) chain successfully assembled with existing collagen VI chains, impacting extracellular matrix assembly.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Collagen VI is a crucial component of the extracellular matrix, essential for tissue structure and integrity.
- The known collagen VI family comprises alpha1(VI), alpha2(VI), and alpha3(VI) chains, forming heterotrimeric molecules.
- Understanding the full diversity of collagen VI chains is vital for comprehending its assembly and function.
Purpose of the Study:
- To identify and characterize novel collagen VI genes and their encoded protein chains.
- To investigate the expression patterns and tissue distribution of the newly discovered collagen VI chains.
- To elucidate the assembly properties of the new collagen VI chains with existing components.
Main Methods:
- Gene identification and mapping to human chromosome 3q22.1.
- Analysis of protein domain structure, including von Willebrand factor A-like domains.
- mRNA expression analysis using tissue samples.
- Immunohistochemical staining of extracellular matrix components.
- Cell transfection and immunoprecipitation assays to study protein assembly.
Main Results:
- Discovery of three new collagen VI genes: COL6A4, COL6A5, and COL6A6, encoding alpha4(VI), alpha5(VI), and alpha6(VI) chains.
- COL6A4 gene is disrupted in humans; COL6A5 shows restricted expression, while COL6A6 has broad tissue distribution.
- Alpha4(VI) chain successfully co-assembled with endogenous alpha1(VI) and alpha2(VI) chains, forming secreted heterotrimeric molecules.
- Alpha5(VI) and alpha6(VI) chains failed to assemble with existing chains and accumulated intracellularly.
Conclusions:
- The identification of COL6A4, COL6A5, and COL6A6 doubles the collagen VI gene family, introducing new protein chains.
- The alpha4(VI) chain possesses the necessary elements for trimerization with alpha1(VI) and alpha2(VI) chains, contributing to extracellular matrix.
- The distinct assembly behaviors of alpha5(VI) and alpha6(VI) suggest complex regulatory mechanisms governing collagen VI formation and function.
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