Impaired Autophagy in Retinal Pigment Epithelial Cells Induced from iPS Cells obtained from a Patient with Sialidosis

Abstract

Sialidosis type I patient-derived induced pluripotent stem cells (iPSCs) were generated from blood mononuclear cells. During embryoid body-like 3D culture, aggregates of patient-derived iPSCs were irregular in shape and had increased vacuoles filled with lipid droplets and cellular components such as damaged mitochondria. Retinal pigment epithelial cells induced from patient-derived iPSCs showed impaired autophagy flux with decreased formation of LC3 puncta. Sialidosis patient-derived iPSCs could provide a useful tool for investigating the mechanism of the autophagy/ lysosome-mediated degradation system.

Modeling Sialidosis with Neural Precursor Cells Derived from Patient-Derived Induced Pluripotent Stem Cells

“…The sialidosis-iNPCs (G227R-iNPCs and V275A/R347Q-iNPCs) exhibited brightly stained large, perinuclear-clustered, and scattered lysosomes in the peripheral region, while the normal-iNPCs showed lightly stained, smaller lysosomal vesicles with less perinuclear clustering ( Figure 4 A, red). Increasingly, studies have demonstrated that impaired lysosomal function observed in various LSDs is associated with autophagy impairment [ 22 , 28 , 29 , 30 ]. Unstimulated basal levels of autophagic vacuoles were not detectable in either normal- or sialidosis-iNPCs by the CYTO-ID autophagy detection assay; thus, we evaluated the impact of rapamycin, an mTOR-dependent autophagy inducer [ 31 ], in the sialidosis-iNPCs and compared them to normal-iNPCs ( Figure 4 A,B, green).…”

“…Sialidosis-iPSCs, harboring both sialidosis-associated mutations and patient-specific genetic background, offer emerging opportunities to investigate sialidosis at the cellular and molecular level. However, only four reports have been published on sialidosis-iPSC models from patients with different NEU1 mutations [ 21 , 22 , 23 , 24 ]. Two reports demonstrated the establishment of sialidosis-iPSC models with NEU1 mutations c.649G > A/644 T > C, c.1109A > G/c.1109A > G [ 43 ], c.1195_1200dup/c.679G > A [ 23 , 32 ], or c.544 A > G transition and 667–679 deletion from sialidosis patient fibroblasts [ 21 ].…”

“…A review of the literature revealed no additional reports of using those models for the production of an adequate tissue-specific disease model, but they can be a potential source of it. As a tissue-specific disease model, retinal pigment epithelial cells (RPEs) were produced from a salidosis-iPSC model with NEU1 mutations c.239C > T and c.403G > A [ 44 ] and thereby revealed the NEU1 deficiency-associated impaired autophagy in sialidosis-specific RPEs [ 22 ]. Recently, characterization of sialidosis neurons derived from two sialidosis-iPSCs carrying NEU1 D176G or NEU1 P316S has revealed the functional and molecular abnormalities such as defective presynaptic exocytosis and excessive enhancement of AMPA-evoked Ca2 + influx in sialidosis [ 24 ].…”

“…Development of neural lineage cells from disease-specific iPSCs, particularly those derived from neuropathic LSD patients, has contributed to a greater understanding of the neuropathophysiology of LSDs, yielding an effective cellular platform for identifying safer and more effective therapeutic targets [ 16 , 17 , 18 , 19 , 20 ]. Likewise, the development of sialidosis- and tissue-specific cells from iPSCs with sialidosis-associated mutations also offer emerging opportunities to investigate sialidosis at the cellular and molecular level, but they are less studied than other LSDs [ 21 , 22 , 23 , 24 ]. However, there have been a limited number of modeling studies for sialidosis.…”

Possible choroidal hyperpermeability in cherry-red spot: a connection to trans-retinal hyperreflective foveola in type 1 sialidosis

“…This hypothesis aligns with previous evidence of dysregulated autophagy-lysosomal system in the retinal pigment epithelium of Type 1 sialidosis, suggesting that the damaged retinal pigment epithelium disrupts the blood-retinal barrier, thereby increasing the permeability of choroidal capillaries. 4 The abnormal photoreceptor cell homeostasis caused by retinal pigment epithelium dysfunction may affect the foveola, the highest cone photoreceptor area with high energy demand, to a greater extent and contribute to transretinal hyperreflectivity. 5 Further research is required to explore this connection.…”