Dataset Information

Oligomeric A?_1-42 Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

ABSTRACT: Alzheimer's disease-associated amyloid beta (A?) proteins accumulate in the outer retina with increasing age and in eyes of age-related macular degeneration (AMD) patients. To study A?-induced retinopathy, wild-type mice were injected with nanomolar human oligomeric A?_1-42, which recapitulate the A? burden reported in human donor eyes. In vitro studies investigated the cellular effects of A? in endothelial and retinal pigment epithelial (RPE) cells. Results show subretinal A?-induced focal AMD-like pathology within 2 weeks. A? exposure caused endothelial cell migration, and morphological and barrier alterations to the RPE. A? co-localized to late-endocytic compartments of RPE cells, which persisted despite attempts to clear it through upregulation of lysosomal cathepsin B, revealing a novel mechanism of lysosomal impairment in retinal degeneration. The rapid upregulation of cathepsin B was out of step with the prolonged accumulation of A? within lysosomes, and contrasted with enzymatic responses to internalized photoreceptor outer segments (POS). Furthermore, RPE cells exposed to A? were identified as deficient in cargo-carrying lysosomes at time points that are critical to POS degradation. These findings imply that A? accumulation within late-endocytic compartments, as well as lysosomal deficiency, impairs RPE function over time, contributing to visual defects seen in aging and AMD eyes.

SUBMITTER: Lynn SA

PROVIDER: S-EPMC7922851 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Oligomeric Aβ<sub>1-42</sub> Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

Lynn Savannah A SA Johnston David A DA Scott Jenny A JA Munday Rosie R Desai Roshni S RS Keeling Eloise E Weaterton Ruaridh R Simpson Alexander A Davis Dillon D Freeman Thomas T Chatelet David S DS Page Anton A Cree Angela J AJ Lee Helena H Newman Tracey A TA Lotery Andrew J AJ Ratnayaka J Arjuna JA

Cells 20210217 2

Alzheimer's disease-associated amyloid beta (Aβ) proteins accumulate in the outer retina with increasing age and in eyes of age-related macular degeneration (AMD) patients. To study Aβ-induced retinopathy, wild-type mice were injected with nanomolar human oligomeric Aβ<sub>1-42</sub>, which recapitulate the Aβ burden reported in human donor eyes. In vitro studies investigated the cellular effects of Aβ in endothelial and retinal pigment epithelial (RPE) cells. Results show subretinal Aβ-induced ...[more]

PMID: 33671133

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Project description:Obatoclax belongs to a class of compounds known as BH3 mimetics which function as antagonists of Bcl-2 family apoptosis regulators. It has undergone extensive preclinical and clinical evaluation as a cancer therapeutic. Despite this, it is clear that obatoclax has additional pharmacological effects that contribute to its cytotoxic activity. It has been claimed that obatoclax, either alone or in combination with other molecularly targeted therapeutics, induces an autophagic form of cell death. In addition, obatoclax has been shown to inhibit lysosomal function, but the mechanism of this has not been elucidated. We have evaluated the mechanism of action of obatoclax in eight ovarian cancer cell lines. Consistent with its function as a BH3 mimetic, obatoclax induced apoptosis in three cell lines. However, in the remaining cell lines another form of cell death was evident because caspase activation and PARP cleavage were not observed. Obatoclax also failed to show synergy with carboplatin and paclitaxel, chemotherapeutic agents which we have previously shown to be synergistic with authentic Bcl-2 family antagonists. Obatoclax induced a profound accumulation of LC-3 but knockdown of Atg-5 or beclin had only minor effects on the activity of obatoclax in cell growth assays suggesting that the inhibition of lysosomal function rather than stimulation of autophagy may play a more prominent role in these cells. To evaluate how obatoclax inhibits lysosomal function, confocal microscopy studies were conducted which demonstrated that obatoclax, which contains two basic pyrrole groups, accumulates in lysosomes. Studies using pH sensitive dyes demonstrated that obatoclax induced lysosomal alkalinization. Furthermore, obatoclax was synergistic in cell growth/survival assays with bafilomycin and chloroquine, two other drugs which cause lysosomal alkalinization. These studies explain, for the first time, how obatoclax inhibits lysosomal function and suggest that lysosomal alkalinization contributes to the cytotoxic activity of obatoclax.

Dataset Information

Oligomeric A?_1-42 Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

Publications

Oligomeric Aβ<sub>1-42</sub> Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

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Dataset Information

Oligomeric A?1-42 Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

Publications

Oligomeric Aβ<sub>1-42</sub> Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Oligomeric A?_1-42 Induces an AMD-Like Phenotype and Accumulates in Lysosomes to Impair RPE Function.