Decorin is a
small leucine-rich proteoglycan (SLRP) that plays a vital role in many important cellular processes in several tissues including the cornea. A normal constituent of the corneal stroma,
decorin is also found in the majority of connective tissues and is related structurally to other small
proteoglycans. It interacts with various
growth factors such as
epidermal growth factor (
EGF) and
transforming growth factor beta (TGFβ) to regulate processes like
collagen fibrillogenesis, extracellular matrix (ECM) compilation, and cell-cycle progression. Studies have linked
decorin dysregulation to delayed tissue healing in patients with various diseases including
cancer. In the cornea,
decorin is involved in the regulation of transparency, a key function for normal vision. It has been reported that mutations in the
decorin gene are associated with congenital stromal dystrophy, a disease that leads to
corneal opacity and visual abnormalities.
Decorin also antagonizes TGFβ in the cornea, a central regulatory
cytokine in corneal wound healing. Following
corneal injury, increased TGFβ levels induce keratocyte transdifferentiation to myofibroblasts and, subsequently,
fibrosis (
scarring) in the cornea. We recently reported that
decorin overexpression in corneal fibroblasts blocks TGFβ-driven myofibroblast transformation and
fibrosis development in the cornea in vitro suggesting that
decorin gene therapy can be used for the treatment of corneal
scarring in vivo.