Abstract
Abstract: :
Purpose: Hyaluronan (HA) is an important component of extracellular matrix and is synthesized by the enzyme hyaluronan synthetase (HAS1-3). HA specifically binds to several plasma membrane receptors including CD44. This HAS/HA/CD44 signaling system is involved in various biological processes which include cell migration, proliferation, and differentiation . In the eye tissues, HA is a major component of vitreous, and it is also identified in retina and choroids. However, the localization of HAS in the ocular posterior portion has not been examined. In the present study, to understand the possible roles of HAS/HA/CD44 signaling system in the posterior eye segment, we investigated the expression and distribution of HAS isoforms and CD44 mRNA. Methods: The eye tissues were obtained from 12-month-old rabbits. HA was measured by ELISA. HAS isoforms and CD44 mRNA in the posterior segments was examined by using reverse transcription with polymerase chain reaction (RT-PCR). Results: HA was detectable in all samples of vitreous, retina and choroid. The expression of all three HAS isoforms (HAS1, HAS2, and HAS3) was clearly detected in both retina and choroid fractions. In vitreous, however, mRNA expression of these three HAS isoforms was extremely low compared to the clear expression of GAPDH mRNA. Similarly, mRNA expression of CD44 was detected in both retina and choroids, but not in vitreous. Conclusions: The present study confirms that HA is present in both retina and choroid fractions at the detectable levels by ELISA and rabbit retina and choroid also express HAS1-3 mRNAs. These evidences suggest that HA is present in retina and choroid and may be synthesized by HAS of retina and choroids. Furthermore, the evidence of CD44 mRNA expression in retina and choroid may suggest that HAS/HA/CD44 signaling system is important in maintaining the functional structure of retina and choroid.
Keywords: retina • enzymes/enzyme inhibitors • gene/expression