Expression of intracellular filament, collagen, and collagenase genes in diabetic and normal skin after injury

Reports have shown differences in gene expression in the skin of diabetic and normal mice both at baseline and after injury. Cluster analysis identified distinct expression patterns within intermediate filaments and extracellular proteins. This report addresses the effect of diabetes and injury on the expression of keratin-associated proteins, keratin complexes, procollagen, and collagenase (matrix metalloproteinase; MMP) genes. At baseline keratin-associated proteins and keratin complexes gene expression was increased in diabetic mice. After surgery, the level of expression for keratin-associated proteins and keratin complexes genes decreased in diabetic mice, but did not change in normal mice. If the expression of a procollagen gene differed between diabetic and normal mice, the expression was lower in diabetic mice. Procollagen gene expression was elevated after skin excision compared with noninjured skin. At baseline, the level of MMP and tissue inhibitor of metalloproteinase gene expression was comparable between mouse strains. With injury, the expression of several MMP genes was increased in both mouse strains, but to higher levels in diabetic mice. At day 7, the level of MMP-9 activity in granulation tissue was elevated. This alteration may contribute to delayed healing in diabetic mice. Therefore, differences in gene expression exist between mouse strains and can assist in understanding of physiological manifestations, including delayed healing, in diabetic mice.