Collagen Type XII Expression in the Decorin 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, decorin, is known to interact with collagen types XII and XIV.  Collagen types XII and XIV are members of the Fibril Associated Collagens with Interrupted Triple-helices (FACIT) family of collagens, and participate in the three-dimensional architecture of connective tissues.  Type XIV collagen mRNA has been previously shown to be down-regulated in both the decorin and biglycan-null mouse.  It is not currently known if there is a change in the collagen XII expression in decorin null mice.  Objective: The purpose of this study is to determine whether or not the absence of decorin affects type XII collagen expression and consequently the three-dimensional architecture of the extracellular matrix (ECM).  Methods: Protein was extracted from skin samples from age matched wild-type and decorin-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 mouse collagen types XII and I and an enzyme-labeled secondary antibody.  Ethanol fixed skin samples from wild-type and decorin-null mice were embedded in paraffin, sectioned and immunostained with antibodies to collagen types XII and I, and localized with enzyme-linked secondary antibodies.   Results: The decorin-null mice showed a decrease in collagen XII staining on both the Western blot and immunostaining.  Conclusion: The expression of collagen type XII is down-regulated in the skin of decorin-null mice.  This study was supported by the Baylor Oral Health Foundation.