Abstract
Purpose::
Transforming growth factor beta-induced, 68kD (ßig-h3), is a TGF-ß inducible protein found in the extracellular matrix of connective tissues and involved in a variety of cellular processes. Previous studies using microarray analysis indicated that ßig-h3 is elevated in the choroids of marmoset eyes during the compensation of minus lenses. Therefore, this study was designed to examine the distribution and functional role of ßig-h3 in the choroid and sclera.
Methods::
ßig-h3 expression in marmosest choroids was quantified by real-time PCR. Western blot analysis and immunohistochemistry were performed on marmoset choroids and human sclera with an antibody against human ßig-h3. Cell adhesion was assayed in cultures of human scleral fibroblasts by measuring enzyme activities of N-acetyl-ß-D-glucosaminidase.
Results::
ßig-h3 mRNA levels were significantly increased in choroids of minus lens-treated marmoset eyes as compared with choroids of plus lens-treated eyes (+172.26% p≤ 0.05). Western blot analyses detected abundant levels of ßig-h3 in human and marmoset sclera, and substantially lower levels in the choroids of human and marmoset eyes. Additionally, ßig-h3 was localized by immunohistochemistry in the human sclera, in association with collagen fibers, along edges of scleral lamellae. Pre-treatment of tissue culture wells with ßig-h3 (1 - 25 µg) resulted in a decrease in cell attachment of human scleral fibroblasts (HSFs) as compared with wells coated with BSA or fibronectin (-67.11% and -92.14%, respectively, p≤0.05).
Conclusions::
The results of this study suggest that ßig-h3 may be involved in the choroidal response during periods of increased ocular elongation. Additionally, ßig-h3 is abundant in the sclera and may function to inhibit scleral fibroblast attachment to stromal collagen.
Keywords: myopia • choroid • sclera