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Inhibition of TGFBIp expression by lithium: implications for TGFBI-linked corneal dystrophy therapy
Seung-Il Choi1, Bong-Yoon Kim, Shorafidinkhuja Dadakhujaev
1Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea.
Abstract:
PURPOSE. The purpose of this study was to investigate the effects and molecular mechanisms of lithium on inhibition of TGFBIp expression as a potential therapy for TGFBI-linked corneal dystrophy. METHODS. Primary culture corneal fibroblasts were isolated from the corneas of healthy subjects and patients with granular corneal dystrophy type 2 (GCD2) with a homozygous mutation in TGFBI R124H. Levels of TGFBIp and its mRNA in corneal fibroblasts treated with various lithium (LiCl) concentrations were analyzed by Western blot, RT-PCR, and quantitative real-time PCR. RESULTS. LiCl treatment reduced the expression levels of normal and mutant TGFBIp in a dose- and a time-dependent manner. Furthermore, TGF-β1-induced TGFBIp expression decreased by 35% and 67% after treatment with 5 mM and 10 mM LiCl, respectively. LiCl decreased the level of pSmad3 (S423/425) in a dose-dependent manner. Furthermore, LiCl increased the level of pGSK-3α/β (S21/9) in a dose-dependent manner. Also observed was the interaction between GSK-3β and Smad3, which was enhanced by lithium. In addition, Western blot analysis showed that the ratio of LC3-II/LC3-I in corneal fibroblasts increased after LiCl treatment. Cell viability at different doses was greater than 98%, indicating that LiCl did not induce significant corneal fibroblast death. Finally, the observed attenuating effects of LiCl on TGFBIp expression were not the results of cell death. CONCLUSIONS. The accumulation of mutant TGFBIp ultimately leads to the histopathologic and clinical manifestations associated with TGFBI-linked corneal dystrophy. These data strongly suggest that lithium may be used for the prevention or treatment of this disease.
Insights
Lithium chloride (LiCl) effectively reduces transforming growth factor beta induced protein (TGFBIp) expression in corneal fibroblasts. This suggests lithium as a potential therapeutic for TGFBI-linked corneal dystrophy without causing cell death.
Area of Science:
- Ophthalmology
- Molecular Biology
- Pharmacology
Background:
- Transforming growth factor beta induced protein (TGFBIp) accumulation causes TGFBI-linked corneal dystrophy.
- Current treatments for TGFBI-linked corneal dystrophy are limited.
Purpose of the Study:
- To investigate lithium's effects on TGFBIp expression.
- To explore the molecular mechanisms of lithium's action.
- To evaluate lithium as a potential therapy for TGFBI-linked corneal dystrophy.
Main Methods:
- Primary corneal fibroblasts from healthy donors and GCD2 patients were cultured.
- Cells were treated with varying lithium chloride (LiCl) concentrations.
- TGFBIp levels, mRNA, and signaling pathways (Smad3, GSK-3α/β, LC3) were analyzed using Western blot and PCR.
Main Results:
- LiCl dose-dependently reduced normal and mutant TGFBIp expression.
- LiCl inhibited TGF-β1-induced TGFBIp expression.
- LiCl modulated Smad3 and GSK-3α/β phosphorylation, enhanced Smad3-GSK-3β interaction, and increased LC3-II/LC3-I ratio.
- LiCl did not induce significant corneal fibroblast death.
Conclusions:
- Lithium effectively inhibits TGFBIp expression through molecular mechanisms involving Smad3 and GSK-3 signaling.
- Lithium demonstrates potential as a therapeutic agent for preventing or treating TGFBI-linked corneal dystrophy.
