TRIM9 promotes Müller cell-derived retinal stem cells to differentiate into retinal ganglion cells by regulating Atoh7

Glaucoma is a multifactorial, irreversible blinding eye disease characterized by a large number of retinal ganglion cell (RGC) deaths. Muller cell-derived retinal stem cells (RSCs) can be induced to differentiate into RGCs under certain conditions. This study aimed to explore the regulatory effect and mechanism of TRIM9 on the differentiation of Muller cell-derived stem cells into RGCs. First, episcleral vein cauterization was used to induce high intraocular pressure (IOP) rat model. Next, Muller cells were isolated from rat retina, identified and induced to dedifferentiate into RSCs. Finally, RSCs were intervened with lentivirus PGC-FU-TRIM9-GFP transfection or siRNA Atoh7 and induced to redifferentiate into RGCs. In vivo, TRIM9 was highly expressed and Muller cells proliferated abnormally in the high IOP rat model. In vitro, S-100, GFAP, vimentin, and GS were positively expressed in Muller cells isolated from rat retina, and the purity of cells was 97.17%. Under the stimulation of cytokines, the proliferative capacity of the cells and the expression of Nestin and Ki67 gradually increased with the prolongation of culture time. Furthermore, RSCs transfected with the lentiviral vector PGC-FU-TRIM9-GFP displayed a striking morphological feature of long neurites. Additionally, there was a remarkable increase in the fluorescence intensity of Brn-3b and Thy1.1, accompanied by elevated mRNA and protein expression levels of Brn-3b, Thy1.1, and Atoh7. After knocking down Atoh7, the effect of TRIM9 on the above indicators was reversed. TRIM9 might promote the differentiation of Muller cells into RGCs by regulating the expression of Atoh7.