Restoration of impaired lysosomal function mitigates drusen-like deposit formation and cell death in Malattia Leventinese
Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa
Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa
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Research Article Cell biology Ophthalmology

Restoration of impaired lysosomal function mitigates drusen-like deposit formation and cell death in Malattia Leventinese

Abstract

Malattia Leventinese (MAL) is an inherited macular degeneration disorder characterized by retinal drusen formation in adolescence, leading to vision loss. A mutation in the fibulin-3 gene (EFEMP1) causes MAL; however, the mechanisms underlying disease onset and drusen formation remain unclear. In this study, we generated induced pluripotent stem cell–derived retinal pigment epithelial (iPSC-RPE) cells from a patient with MAL to investigate disease mechanisms and potential therapies. MAL iPSC-RPE exhibited fibulin-3 and apolipoprotein E (ApoE) aggregation, increased endoplasmic reticulum stress, and enhanced apoptosis. Long-term culture with photoreceptor outer segments led to drusen-like deposits containing ApoE, complement components, and collagen IV accumulation, and it showed activation of matrix metalloproteinase-2 (MMP2). Untargeted lipid analysis revealed increased hexosylceramide and bis-monoacylglycerophosphate levels in MAL iPSC-RPE cells. A key pathological feature was lysosomal dysfunction associated with altered regulation of lysosomal gene programs, including reduced transcription factor EB transcript levels. Treatment with trehalose, a lysosome-modulating compound, increased lysosomal content and function, reducing drusen-like deposit formation, inhibiting MMP2 activation, and suppressing apoptosis. This study highlighted lysosomal dysfunction as a contributor to RPE damage, drusen-like deposit accumulation, and extracellular matrix degradation. Pharmacological restoration of lysosomal function alleviated these defects, suggesting therapeutic potential for MAL and other drusen-related diseases, including age-related macular degeneration.

Authors

Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa

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Figure 7

Lysosomal dysfunction in MAL iPSC-RPE cells.

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Lysosomal dysfunction in MAL iPSC-RPE cells. iPSC-RPE cells were culture...
iPSC-RPE cells were cultured for 4 weeks. Subsequently, cells were incubated with or without POS for 2 or 4 weeks. (A) FACS analysis of lysosome function using LysoTracker Green. The mean fluorescence intensity at 4 weeks after POS treatment was normalized to the mean fluorescence intensity at 2 weeks of POS exposure. (B and C) Western blot and statistical analyses of phosphorylated epidermal growth factor receptor (pEGFR) in NOR and MAL iPSC-RPE cells treated with epidermal growth factor (EGF) for 6 hours, followed by measurements at 0, 15, 30, and 60 minutes after EGF removal. *P < 0.05, ***P < 0.005; P values were calculated using a linear mixed-effects model followed by Tukey’s HSD test. In C, comparisons were made versus 0 min. n = 5 (A) and n = 3 (C). Data are shown as mean ± SD.