Wei Wei, Hu Piaopiao, Qin Mengqi, Chen Guiping, Wang Feifei, Yao Shengrui, Jin Ming, Xie Zhi, Zhang Xu
Jiangxi Provincial Key Laboratory for Ophthalmology, Jiangxi Clinical Research Center of Ophthalmic Disease, Affiliated Eye Hospital of Nanchang University, Nanchang, China.
Front Neurosci. 2022 Feb 4;16:840443. doi: 10.3389/fnins.2022.840443. eCollection 2022.
Sirtuin 4 (SIRT4) is one of seven mammalian sirtuins that possesses ADP-ribosyltransferase, lipoamidase and deacylase activities and plays indispensable role in metabolic regulation. However, the role of SIRT4 in the retina is not clearly understood. The purpose of this study was to explore the location and function of SIRT4 in the retina. Therefore, immunofluorescence was used to analyze the localization of SIRT4 in rat, mouse and human retinas. Western blotting was used to assess SIRT4 and glutamine synthetase (GS) protein expression at different developmental stages in C57BL/6 mice retinas. We further analyzed the retinal structure, electrophysiological function and the expression of GS protein in SIRT4-deficient mice. Excitotoxicity was caused by intravitreal injection of glutamate (50 nmol) in mice with long-term intraperitoneal injection of resveratrol (20 mg/Kg), and then retinas were subjected to Western blotting and paraffin section staining to analyze the effect of SIRT4 on excitotoxicity. We show that SIRT4 co-locates with Müller glial cell markers (GS and vimentin). The protein expression pattern of SIRT4 was similar to that of GS, and both increased with development. There were no significant retinal structure or electrophysiological function changes in 2-month SIRT4-deficient mice, while the expression of GS protein was decreased. Moreover, long-term administration of resveratrol can upregulate the expression of SIRT4 and GS while reducing the retinal injury caused by excessive glutamate. These results suggest that SIRT4 is highly expressed in retinal Müller glial cells and is relevant to the expression of GS. SIRT4 does not appear to be essential in retinal development, but resveratrol, as an activator of SIRT4, can upregulate GS protein expression and protect the retina from excitotoxicity.
沉默调节蛋白4（SIRT4）是七种哺乳动物沉默调节蛋白之一，具有ADP核糖基转移酶、硫辛酰胺酶和去酰基酶活性，在代谢调节中发挥着不可或缺的作用。然而，SIRT4在视网膜中的作用尚不清楚。本研究的目的是探讨SIRT4在视网膜中的定位和功能。因此，采用免疫荧光法分析SIRT4在大鼠、小鼠和人类视网膜中的定位。采用蛋白质免疫印迹法评估C57BL/6小鼠视网膜不同发育阶段SIRT4和谷氨酰胺合成酶（GS）的蛋白表达。我们进一步分析了SIRT4基因敲除小鼠的视网膜结构、电生理功能和GS蛋白的表达。通过长期腹腔注射白藜芦醇（20mg/Kg）的小鼠玻璃体内注射谷氨酸（五十纳摩尔）诱导兴奋毒性，然后对视网膜进行蛋白质免疫印迹和石蜡切片染色，以分析SIRT4对兴奋毒性的影响。我们发现SIRT4与米勒胶质细胞标志物（GS和波形蛋白）共定位。SIRT4的蛋白表达模式与GS相似，且两者均随发育而增加。两个月大的SIRT4基因敲除小鼠视网膜结构和电生理功能无明显变化，但GS蛋白表达降低。此外，长期给予白藜芦醇可上调SIRT4和GS的表达，同时减少过量谷氨酸引起的视网膜损伤。这些结果表明，SIRT4在视网膜米勒胶质细胞中高表达，且与GS的表达相关。SIRT4在视网膜发育中似乎并非必不可少，但白藜芦醇作为SIRT4的激活剂，可上调GS蛋白表达并保护视网膜免受兴奋毒性。
