Collagen Type XII Expression in the Biglycan Null Mouse

Small Leucine-Rich Proteoglycans (SLRP’s) comprise a family of proteoglycans that are thought to play a role in protein-protein interactions and tissue assembly.  One member of this family, biglycan (BGN), interacts with type I collagen.  Collagen type XII is a member of the Fibril Associated Collagens with Interrupted Triple-helices (FACIT) family of collagens and participates in the three-dimensional architecture of dense connective tissue.  Another member of the FACIT family, collagen type XIV, has previously been shown to be down-regulated in the biglycan-null mouse.  Both types XII and XIV interact with collagen type I fibrils.  Objective: The purpose of this study is to determine whether or not the absence of biglycan affects type XII collagen expression and consequently the three-dimensional architecture of the extracellular matrix (ECM).  Method: Protein was extracted from skin samples from wild-type and biglycan-null mice.  The protein was quantified, and equal amounts were separated on a polyacrylamide gradient gel.  The proteins were electroblotted onto a nylon membrane, and detected by primary antibodies against collagen types XII and I and an enzyme-labeled secondary antibody.  The positive bands were identified by exposing the blot to radiograph film. The films were scanned and the labeled bands of the appropriate size were quantified by comparing the band densities.  Result: The biglycan-null mice showed a decrease in collagen XII staining on the Western blot.  Conclusion: There is a decrease in the collagen type XII protein expression in the biglycan-null mice.  This study was supported by the Baylor Oral Health Foundation.