Zhang Ye, Li Tingting, Cai Xuan, Long Da, Wang Xiangning, Liu Chang, Wu Qiang
Department of Ophthalmology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.
Cell Death Discov. 2022 Feb 14;8(1):63. doi: 10.1038/s41420-022-00861-5.
Retinal neurodegeneration develops early in the course of diabetic retinopathy (DR), and our previous research showed that succinate accumulation results in retinal ganglion cells (RGCs) dysfunction in the retinas of rats with DR. Succinate can enhance lysine succinylation, but the succinylation of DR is not well understood. In this study, we investigated the role of the succinylome in DR and identified the key factor in this process. TMT labeling and LC-MS/MS analysis were combined to quantify the differentially succinylated proteins between vitreous humor (VH) samples from DR and non-DR patients. A total of 74 sites in 35 proteins were differentially succinylated between DR and non-DR vitreous humor samples, among which succinylation of the K108 site of optineurin (OPTN K108) in the defense response was enriched by GO analysis based on the biological process category. Then, using a streptozotocin (STZ)-induced diabetic rat model, R28 cells and primary rat RGCs (rRGCs), we demonstrated that OPTN underwent lysine succinylation in the retinas of rats with DR and that OPTN K108 mediated autophagic flux blockade under high-glucose (HG) conditions. Sirt5 can desuccinylate OPTN K108, thus protecting RGCs function from high glucose-induced RGCs autophagic flux blockade in the diabetic retina. Overall, desuccinylation of OPTN is an essential adaptive mechanism for ameliorating autophagic flux blockade in RGCs under DR conditions, and targeting the Sirt5-desuccK108-OPTN axis may thus open an avenue for therapeutic intervention in RCGs dysfunction.
视网膜神经变性在糖尿病视网膜病变（DR）病程早期就会出现，我们之前的研究表明，琥珀酸积累会导致DR大鼠视网膜中的视网膜神经节细胞（RGCs）功能障碍。琥珀酸可增强赖氨酸琥珀酰化，但DR中的琥珀酰化情况尚未完全明确。在本研究中，我们探究了琥珀酰化蛋白质组在DR中的作用，并确定了这一过程中的关键因素。我们结合TMT标记和液相色谱-串联质谱（LC-MS/MS）分析，对DR患者和非DR患者玻璃体液（VH）样本之间差异琥珀酰化的蛋白质进行定量。在DR和非DR玻璃体液样本之间，共有35种蛋白质中的74个位点存在差异琥珀酰化，其中基于生物过程类别进行的基因本体（GO）分析显示，防御反应中视紫质（OPTN K108）的K108位点的琥珀酰化显著富集。然后，我们使用链脲佐菌素（STZ）诱导的糖尿病大鼠模型、R28细胞和原代大鼠RGCs（rRGCs），证明了OPTN在DR大鼠视网膜中发生赖氨酸琥珀酰化，并且OPTN K108在高糖（HG）条件下介导自噬流阻滞。沉默调节蛋白5（Sirt5）可使OPTN K108去琥珀酰化，从而保护RGCs功能免受糖尿病视网膜中高糖诱导的RGCs自噬流阻滞的影响。总体而言，OPTN的去琥珀酰化是改善DR条件下RGCs自噬流阻滞的一种重要适应性机制，因此靶向Sirt5-去琥珀酰化K108-OPTN轴可能为RCGs功能障碍的治疗干预开辟一条途径。
