Institute of Life Sciences, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China.
Key Lab of Organ Development and Regeneration of Zhejiang Province, Hangzhou, Zhejiang, China.
Sci Rep. 2021 Aug 18;11(1):16798. doi: 10.1038/s41598-021-96332-5.
Tunneling nanotube (TNT), a dynamic cell-cell contact, is dependent on actin polymerization. TNTs are efficient in transporting ions, proteins and organelles intercellularly, which are important mechanisms in physiological and pathological processes. Reported studies on the existence and function of TNTs among neural cells focus on cultured cell for the convenience in detecting TNTs' ultrastructure. In this study, the adeno-associated virus (AAV-GFAP-EGFP-p2A-cre) was injected into the cerebral cortex of knock-in mice ROSA26 GNZ. GFAP promoter initiated the expression of enhanced green fluorescent protein (EGFP) in infected astrocytes. At 10 days post injection (10 DPI), EGFP transferred from astrocytes in layer I-III to neurons in layer V. The dissemination of EGFP was not through endocytosis or exosome. Applying microscopes, we found that the intercellular transportation of EGFP through contact connection was F-actin dependent. Therefore, we concluded that EGFP transported from astrocytes to neurons in cortex via F-actin dependent TNTs. This study first proved that proteins transported intercellularly via TNTs in brain.
隧道纳米管（TNT）是一种动态的细胞间接触，依赖于肌动蛋白聚合。TNT 能够有效地在细胞间运输离子、蛋白质和细胞器，这是生理和病理过程中的重要机制。目前关于神经细胞之间 TNT 存在和功能的研究主要集中在培养细胞上，这是为了方便检测 TNT 的超微结构。在这项研究中，腺相关病毒（AAV-GFAP-EGFP-p2A-cre）被注射到 ROSA26 GNZ 基因敲入小鼠的大脑皮层。GFAP 启动子在感染的星形胶质细胞中启动增强型绿色荧光蛋白（EGFP）的表达。在注射后 10 天（10 DPI），EGFP 从 I-III 层的星形胶质细胞转移到 V 层的神经元。EGFP 的传播不是通过内吞作用或外泌体。应用显微镜，我们发现 EGFP 通过接触连接的细胞间运输依赖于 F-肌动蛋白。因此，我们得出结论，EGFP 通过 F-肌动蛋白依赖的 TNT 从星形胶质细胞转运到皮质中的神经元。这项研究首次证明了蛋白质通过 TNT 在大脑中进行细胞间运输。
