Department of Biochemistry and Structural Biology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA; Department of Ophthalmology, Second Xiangya Hospital, Central South University, Changsha, 410011, China; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, 410011, China.
Department of Biochemistry and Structural Biology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA; Department of Ophthalmology, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Redox Biol. 2024 Jul;73:103216. doi: 10.1016/j.redox.2024.103216. Epub 2024 May 28.
Long-lived lens fiber cells require a robust cellular protective function against oxidative insults to maintain their hemostasis and viability; however, the underlying mechanism is largely obscure. In this study, we unveiled a new mechanism that protects lens fiber cells against oxidative stress-induced cell death. We found that mechano-activated connexin (Cx) hemichannels (HCs) mediate the transport of glutathione (GSH) into chick embryonic fibroblasts (CEF) and primary lens fiber cells, resulting in a decrease in the accumulation of intracellular reactive oxygen species induced by both HO and ultraviolet B, providing protection to lens fiber cells against cell apoptosis and necrosis. Furthermore, HCs formed by both homomeric Cx50 or Cx46 and heteromeric Cx50/Cx46 were mechanosensitive and could transport GSH into CEF cells. Notably, mechano-activated Cx50 HCs exhibited a greater capacity to transport GSH than Cx46 HCs. Consistently, the deficiency of Cx50 in single lens fiber cells led to a higher level of oxidative stress. Additionally, outer cortical short lens fiber cells expressing full length Cxs demonstrated greater resistance to oxidative injury compared to central core long lens fibers. Taken together, our results suggest that the activation of Cx HCs by interstitial fluid flow in cultured epithelial cells and isolated fiber cells shows that HCs can serve as a pathway for moving GSH across the cell membrane to offer protection against oxidative stress.
长寿命的晶状体纤维细胞需要强大的细胞保护功能来抵御氧化应激,以维持其止血和存活能力;然而,其潜在机制在很大程度上尚不清楚。在这项研究中,我们揭示了一种保护晶状体纤维细胞免受氧化应激诱导的细胞死亡的新机制。我们发现机械激活连接蛋白 (Cx) 半通道 (HCs) 将谷胱甘肽 (GSH) 转运到鸡胚成纤维细胞 (CEF) 和原代晶状体纤维细胞中,减少了 HO 和紫外线 B 诱导的细胞内活性氧的积累,为晶状体纤维细胞提供了针对细胞凋亡和坏死的保护。此外,由同源 Cx50 或 Cx46 以及异源 Cx50/Cx46 形成的 HCs 是机械敏感的,可以将 GSH 转运到 CEF 细胞中。值得注意的是,机械激活的 Cx50 HCs 比 Cx46 HCs 具有更大的转运 GSH 的能力。一致地,单个晶状体纤维细胞中 Cx50 的缺失导致更高水平的氧化应激。此外,表达全长 Cxs 的外皮质短晶状体纤维细胞比中央核心长晶状体纤维对氧化损伤表现出更强的抵抗力。总之,我们的结果表明,培养的上皮细胞和分离的纤维细胞中细胞间隙液流对 Cx HCs 的激活表明 HCs 可以作为跨细胞膜移动 GSH 的途径,提供对氧化应激的保护。