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Tomohiko Usui, Shiro Amano, Tetsuro Oshika, Kaori Suzuki, Kazunori Miyata, Makoto Araie, Paraskevi Heldin, Hidetoshi Yamashita; Expression Regulation of Hyaluronan Synthase in Corneal Endothelial Cells. Invest. Ophthalmol. Vis. Sci. 2000;41(11):3261-3267.
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© ARVO (1962-2015); The Authors (2016-present)
purpose. Our previous study showed that hyaluronan synthase (HAS), the enzyme
protein of hyaluronan (HA) biosynthesis, is expressed in ocular tissues
including the corneal endothelium. In the current study, the mechanism
that regulates HAS expression in bovine corneal endothelial cells
(BCECs) was investigated.
methods. Cultured BCECs were used. HAS expression in BCECs at the mRNA level was
detected by reverse transcription–polymerase chain reaction (RT-PCR)
and Northern blot analysis. The effects of transforming growth factor
(TGF)-β and platelet-derived growth factor (PDGF)-BB on HAS
expression were examined by quantitative RT-PCR. The involvement of the
Smad family (intracellular signal transducer of TGF-β) was also
investigated. The expression of HAS in BCECs at the protein level was
confirmed by immunocytochemistry and Western blot analysis.
results. Three HAS isoforms in BCECs were expressed at the mRNA level. The
transcriptional sizes of each HAS in BCECs were 4.9 kb for HAS1, 2.8 kb
for HAS2, and 1.6 kb for HAS3. The expression of HAS2 at the mRNA level
was stimulated by TGF-β1 and/or PDGF-BB treatment. In contrast, HAS1
and HAS3 expression was not affected by these growth factors. The
additive effects of TGF-β1 and PDGF-BB were observed in the
stimulation of the expression levels of HAS2. HAS2 upregulation by
these growth factors was also detected by Western blot analysis. The
stimulation of the expression of HAS2 at the mRNA level by TGF-β was
accelerated by the overexpression of Smad2, Smad3, and Smad4 and
inhibited by that of Smad7, all of which were confirmed to be involved
in the signal transduction from TGF-β through HAS expression.
conclusions. Although three HAS isoforms were expressed in the corneal endothelial
cells, the expression of HAS2 was upregulated by TGF-β1 and/or
PDGF-BB. HAS2 expression was regulated by TGF-β through Smad family
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