Targeting the SNAI1-LAMP3 axis to restore lysosomal function and alleviate autophagic flux impairment to delay...

Retinal degenerative diseases are a leading cause of irreversible blindness. Their pathogenesis is intricately linked to oxidative stress-induced dysfunction of retinal pigment epithelial (RPE) cells and subsequent retinal degeneration. Macroautophagy/autophagy, a critical cellular degradation pathway, plays a vital role in maintaining RPE homeostasis, yet its dysregulation in retinal degenerative diseases remains poorly understood. In this study, we observed that sodium iodate (NaIO₃), an oxidative stress inducer, triggered lysosomal dysfunction via lysosomal membrane permeabilization (LMP), thereby impairing autophagic flux in RPE cells and exacerbating retinal degeneration. RNA sequencing identified LAMP3 (lysosomal-associated membrane protein 3) as a downregulated gene following NaIO₃ treatment. Functionally, LAMP3 overexpression alleviated NaIO₃-induced LMP, improved lysosomal function, and alleviated autophagic impairment. Furthermore, upregulation of LAMP3 reduced oxidative stress and apoptosis in RPE cells, while alleviating retinal degeneration in a NaIO₃-induced mouse model. Mechanistically, our data suggested that NaIO₃ upregulated the transcription factor SNAI1, which acts as a transcriptional repressor of LAMP3. SNAI1 knockdown increased LAMP3 expression, thereby facilitating the recovery of lysosomal function and the alleviation of autophagic impairment. Collectively, our findings indicate that the SNAI1-LAMP3 axis contributes to the regulation of the autophagy-lysosomal pathway in retinal degeneration, highlighting a potential therapeutic target for delaying disease progression.Abbreviations: AMD: age-related macular degeneration; AO: acridine orange; Baf A1: bafilomycin A₁; BAX: BCL2-associated X protein; BCL2: B cell leukemia/lymphoma 2; BSA: bovine serum albumin; CCK-8: cell counting kit-8; ChIP: chromatin immunoprecipitation; CM-H₂DCFDA: chloromethyl-2',7'-dichlorodihydrofluorescein diacetate; CTSD: cathepsin D; DAPI: 4',6-diamidino-2-phenylindole; DEGs: differentially expressed genes; DHE: dihydroethidium; EdU: 5-ethynyl-2'-deoxyuridine; ERG: electroretinography; GSEA: gene set enrichment analysis; H&E: hematoxylin and eosin; HsRPE: human primary retinal pigment epithelial; JC-1: 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide; LAMP1: lysosomal-associated membrane protein 1; LAMP2: lysosomal-associated membrane protein 2; LAMP3: lysosomal-associated membrane protein 3; LGALS3: lectin, galactose binding, soluble 3; LLOMe: leu-leu methyl ester; LMP: lysosomal membrane permeabilization; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MMP: mitochondrial membrane potential; NAC: N-acetyl-L-cysteine; NaIO₃: sodium iodte; NC: negative control; OCT: optical coherence tomography; PCA: principal component analysis; PI: propidium iodide; qRT-PCR: quantitative real-time polymerase chain reaction; Rapa: rapamycin; ROS: reactive oxygen species; RP: retinitis pigmentosa; RPE: retinal pigment epithelium; RPE65: retinal pigment epithelium 65; siRNA: small interfering RNA; SNAI1: snail family zinc finger 1; SQSTM1/p62: sequestosome 1; TJP1/ZO-1: tight junction protein 1; ZNF135: zinc finger protein 135.