Ihadadene Katia, Fallatah Azdah Hamed A, Zhu Yu, Tolone Arianna, Paquet-Durand François
Graduate School INTHERAPI, Burgundy University, Dijon, France.
Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
J Neurochem. 2025 Apr;169(4):e70072. doi: 10.1111/jnc.70072.
The axons of retinal ganglion cells (RGCs) form the optic nerve, which relays visual information to the brain. RGC degeneration is the root cause of a variety of blinding diseases linked to optic nerve damage, including glaucoma, the second leading cause of blindness worldwide. The underlying cellular mechanisms of RGC degeneration are largely unclear; yet, they have been connected to excessive production of the signalling molecule nitric oxide (NO) by nitric oxide synthase (NOS). NO activates soluble guanylate cyclase (sGC), which subsequently produces the second messenger cyclic guanosine monophosphate (cGMP). This, in turn, activates protein kinase G (PKG), which can phosphorylate downstream protein targets. To study the role of NO/cGMP/PKG signalling in RGC degeneration, we used organotypic retinal explant cultures in which the optic nerve had been severed. We assessed the activity of NOS, RGC death and survival at different times after optic nerve transection. While NOS activity was high right after optic nerve transection, significant RGC loss occurred with a 24-48-h delay. We then treated retinal explants with inhibitors selectively targeting either NOS, sGC, PKG, or Kv1.3 and Kv1.6 voltage-gated potassium channels. While all four treatments reduced RGC death, the PKG inhibitor CN238 and the Kv-channel blocker Margatoxin (MrgX) showed the most pronounced rescue effects. Our results confirm an involvement of NO/cGMP/PKG signalling in RGC degeneration, highlight the potential of PKG and Kv1-channel targeting drugs for treatment development, and further suggest organotypic retinal explant cultures as a useful model for investigations into optic nerve damage.
视网膜神经节细胞（RGCs）的轴突形成视神经，将视觉信息传递至大脑。RGCs退化是多种与视神经损伤相关致盲疾病的根本原因，包括青光眼，它是全球第二大致盲原因。RGCs退化的潜在细胞机制在很大程度上尚不清楚；然而，它们与一氧化氮合酶（NOS）过度产生信号分子一氧化氮（NO）有关。NO激活可溶性鸟苷酸环化酶（sGC），随后sGC产生第二信使环磷酸鸟苷（cGMP）。反过来，这又激活蛋白激酶G（PKG），PKG可使下游蛋白质靶点磷酸化。为了研究NO/cGMP/PKG信号通路在RGCs退化中的作用，我们使用了视神经已被切断的视网膜器官型外植体培养物。我们评估了视神经横断后不同时间的NOS活性、RGCs的死亡和存活情况。虽然视神经横断后NOS活性立即升高，但显著的RGCs损失在24 - 48小时后出现。然后，我们用选择性靶向NOS、sGC、PKG或Kv1.3和Kv1.6电压门控钾通道的抑制剂处理视网膜外植体。虽然所有四种处理都减少了RGCs的死亡，但PKG抑制剂CN238和钾通道阻滞剂玛格毒素（MrgX）显示出最显著的挽救效果。我们的结果证实了NO/cGMP/PKG信号通路参与RGCs退化，突出了PKG和靶向Kv1通道的药物在治疗开发中的潜力，并进一步表明视网膜器官型外植体培养是研究视神经损伤的有用模型。
