Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States; Department of Ophthalmology, Yonsei University Wonju College of Medicine, Wonju, South Korea.
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Ocul Surf. 2018 Oct;16(4):463-469. doi: 10.1016/j.jtos.2018.07.004. Epub 2018 Jul 7.
To evaluate the role of PPARγ in regulating meibocyte differentiation and lipid synthesis in a human meibomian gland epithelial cell line (hMGEC).
HMGEC were exposed to the PPARγ agonist, Rosiglitazone, from 10-50 μM. Cultures were also exposed to specific PPARγ antagonist, T0070907, to block PPARγ receptor signaling. Cells were then stained with Ki-67 and LipidTox to determine the effects on cell cycling and lipid synthesis, respectively. Expression of meibocyte differentiation related proteins, ADFP, PPARγ, ELOVL4, and FABP4, were evaluated by quantitative PCR and western blotting. A human corneal epithelial cell line (hTCEpi) was used as a control.
Rosiglitazone significantly decreased Ki-67 staining within 2 days in a dose-dependent manner (P = 0.003) and increased lipid accumulation in hMGEC in a dose dependent manner. T0070907 suppressed both lipid droplet synthesis and cell cycle exit. Rosiglitazone significantly upregulated expression of ADFP, PPARγ, ELOVL4, and FABP4 by 9.6, 2.7, 2.6, and 3.3 fold on average (all P < 0.05 except for FABP4, P = 0.057) in hMGEC. T0070907 significantly abrogated rosiglitazone-induced upregulation of these genes when treated prior to rosiglitazone treatment (all P < 0.05). The observed lipogenic differentiation response was not duplicated in hTCEpi after exposure to rosiglitazone.
Rosiglitazone induced cell cycle exit and upregulation of lipogenic gene expression leading to lipid accumulation in hMGEC. These effects were suppressed by PPARγ antagonist indicating that PPARγ signaling specifically directs lipogenesis in hMGEC. These findings suggest that PPARγ plays a critical role in meibocyte differentiation.
评估过氧化物酶体增殖物激活受体γ（PPARγ）在调控人眼睑板腺上皮细胞（hMGEC）中细胞分化和脂质合成中的作用。
用不同浓度（10-50μM）的过氧化物酶体增殖物激活受体γ激动剂罗格列酮（Rosiglitazone）处理 hMGEC。同时，用特定的过氧化物酶体增殖物激活受体γ拮抗剂 T0070907 处理细胞以阻断过氧化物酶体增殖物激活受体γ受体信号。然后用 Ki-67 和 LipidTox 分别染色以确定细胞周期和脂质合成的影响。通过定量 PCR 和 Western blot 评估与 meibocyte 分化相关的蛋白 ADFP、PPARγ、ELOVL4 和 FABP4 的表达。用人角膜上皮细胞系（hTCEpi）作为对照。
罗格列酮以剂量依赖性方式在 2 天内显著降低 Ki-67 染色（P=0.003），并以剂量依赖性方式增加 hMGEC 中的脂质积累。T0070907 抑制脂质滴合成和细胞周期退出。罗格列酮使 ADFP、PPARγ、ELOVL4 和 FABP4 的表达分别平均上调 9.6、2.7、2.6 和 3.3 倍（除 FABP4 外，均 P<0.05；P=0.057）。T0070907 显著抑制了罗格列酮处理前处理 T0070907 对这些基因的上调作用（均 P<0.05）。在暴露于罗格列酮后，hTCEpi 并未出现脂生成分化反应。
罗格列酮诱导细胞周期退出和上调脂生成基因表达，导致 hMGEC 中脂质积累。这些作用被 PPARγ 拮抗剂抑制，表明 PPARγ 信号特异性指导 hMGEC 中的脂生成。这些发现表明 PPARγ 在 meibocyte 分化中起着关键作用。
