Lumican belongs to the
small leucine-rich proteoglycan family and has an important role in the regulation of corneal and dermal
collagen fiber assembly. Recently,
lumican mRNA was found in the heart and its high expression was reported during wound healing of the cornea. In the present study, the expression and role of
lumican in
fibrosis of an ischemic and reperfused rat heart were examined. The expression level of
lumican mRNA increased in the ischemic and reperfused rat heart and was highest on the fourth week.
Lumican protein existed in the forms of core
protein and
proteoglycan in the control rat heart. The amount of
lumican in the form of
proteoglycan increased, and that as the form
glycoprotein was newly detected in the ischemic and reperfused rat heart on the fourth week. In the control heart,
lumican was weakly expressed in the
collagen fibers of the perivascular area, but it was expressed strongly in many capillary endothelial cells in the ischemic lesion on day 1. After 3 days,
lumican was localized in
collagen fibers and in the fibroblasts of fibrotic lesions. A few myocardial cells close to the ischemic lesion expressed
lumican mRNA.
Lumican is considered to play an important role in the fibrillogenesis of the ischemic and reperfused rat heart.