Collagen Type XII Expression in the Decorin/Biglycan Null Mouse

Decorin (DCN) and biglycan (BGN) are both members of a family of proteoglycans known as Small Leucine-Rich Proteoglycans (SLRP).  One of the roles that this family of molecules has been shown to play is in protein-protein interactions.  Among these interactions, BGN and DCN have been shown to interact with collagen type XIV.  Collagen XIV is a member of the family, Fibril-Associated Collagens with Interrupted Triple-helices (FACIT).  Previous experiments have shown that mRNA for type XIV collagen is down-regulated in both BGN-null and DCN-null mice.  It has also been shown that another FACIT, type XII collagen protein expression is reduced in both BGN and DCN null mouse skin.  Objective: The purpose of this study is to determine if there is a change in collagen type XII protein expression in the BGN^-/0/DCN^-/- mouse skin.  Methods: Protein was extracted from skin samples from age-matched wild-type and BGN^-/0/DCN^-/- mice, and then quantitated.  Equal amounts of total protein extract were separated under reducing conditions by PAGE.  The separated proteins were electroblotted onto nylon membranes, and then reacted with either an anti-mouse collagen XII or collagen I antibody.  The blots were then reacted with 2º antibody and exposed to radiographic film.  The proteins were quantified by measuring the density of the signal on the film.  Results: When compared to the wild-type, the double knockout animal showed a significant decrease in type XII protein.  Conclusion: Type XII collagen protein expression is decreased in BGN^-/0/DCN^-/- mice.  This study was supported by the Baylor Oral Health Foundation.