RSL1D1 deficiency reduces FTH1 stability and induces ferroptosis and senescence in retinal pigment epithelial cells in diabetic retinopathy.

Ribosomal L1 domain-containing protein 1 (RSL1D1) is an RNA-binding protein that relates to senescence. Nevertheless, the mechanism of RSL1D1 in modulating senescence and ferroptosis in diabetic retinopathy (DR) remains undefined. The DR mice were developed by intraperitoneal injection of STZ, and AAV targeting retinal pigment epithelium (RPE) was used for gene intervention. ARPE-19 cells were infected using oe-RSL1D1 and sh-FTH1 lentivirus before 30 mM high glucose (HG) exposure. Cell damage was assessed by measuring the expression of senescence and ferroptosis markers in ARPE-19 cells, along with oxidative stress indicators and Fe2+ levels. RSL1D1 and FTH1 expression were significantly reduced in the RPE layer of diabetic mice and HG-induced ARPE-19 cells. Downregulation of RSL1D1 led to RPE cell senescence and dysregulated iron homeostasis-induced ferroptosis. HG treatment reduced the interaction between RSL1D1 protein and FTH1 mRNA in ARPE-19 cells, while RSL1D1 overexpression enhanced this interaction, thereby stabilizing FTH1 mRNA expression. The alleviating effects of RSL1D1 overexpression on retinal pigment epithelium cell senescence and ferroptosis in vitro and in vivo were compromised by FTH1 knockdown. Overall, this study unveils a posttranscriptional regulation of FTH1 by RSL1D1 and uncovers the implication of RSL1D1/FTH1 in cellular senescence and ferroptosis in DR.