The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemungu, Seoul 03722, Korea.
Corneal Dystrophy Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemungu, Seoul 03722, Korea.
Int J Mol Sci. 2022 Aug 22;23(16):9478. doi: 10.3390/ijms23169478.
Meibomian gland dysfunction is one of the main causes of dry eye disease and has limited therapeutic options. In this study, we investigated the biological function of the beta 2-adrenergic receptor (ADRB2)/protein kinase A (PKA) pathway in lipid synthesis and its underlying mechanisms in human meibomian gland epithelial cells (HMGECs). HMGECs were cultured in differentiation media with or without forskolin (an activator of adenylate cyclase), salbutamol (an ADRB2 agonist), or timolol (an ADRB2 antagonist) for up to 4 days. The phosphorylation of the cAMP-response element-binding protein (CREB) and the expression of peroxisome proliferator activator receptor (PPAR)γ and sterol regulatory element-binding protein (SREBP)-1 were measured by immunoblotting and quantitative PCR. Lipid synthesis was examined by LipidTOX immunostaining, AdipoRed assay, and Oil Red O staining. PKA pathway activation enhanced PPARγ expression and lipid synthesis in differentiated HMGECs. When treated with agonists of ADBR2 (upstream of the PKA signaling system), PPARγ expression and lipid synthesis were enhanced in HMGECs. The ADRB2 antagonist timolol showed the opposite effect. The activation of the ADRB2/PKA signaling pathway enhances lipid synthesis in HMGECs. These results provide a potential mechanism and therapeutic target for meibomian gland dysfunction, particularly in cases induced by beta-blocker glaucoma drugs.
睑板腺功能障碍是干眼症的主要原因之一，其治疗选择有限。在这项研究中，我们研究了β 2-肾上腺素能受体（ADRB2）/蛋白激酶 A（PKA）通路在脂质合成中的生物学功能及其在人睑板腺上皮细胞（HMGECs）中的潜在机制。HMGECs 在分化培养基中培养，或加入福司可林（腺苷酸环化酶激活剂）、沙丁胺醇（ADRB2 激动剂）或噻吗洛尔（ADRB2 拮抗剂）培养，最长达 4 天。通过免疫印迹和定量 PCR 测量 cAMP 反应元件结合蛋白（CREB）的磷酸化和过氧化物酶体增殖物激活受体（PPAR）γ和固醇调节元件结合蛋白（SREBP）-1的表达。通过 LipidTOX 免疫染色、AdipoRed 测定和油红 O 染色检测脂质合成。PKA 信号通路的激活增强了分化的 HMGECs 中 PPARγ 的表达和脂质合成。当用 ADBR2 的激动剂（PKA 信号系统的上游）处理 HMGECs 时，PPARγ 的表达和脂质合成增强。ADRB2 拮抗剂噻吗洛尔则表现出相反的效果。ADRB2/PKA 信号通路的激活增强了 HMGECs 中的脂质合成。这些结果为睑板腺功能障碍提供了一个潜在的机制和治疗靶点，特别是在β受体阻滞剂类青光眼药物诱导的情况下。
