Investigating lysosomal exocytosis as a pathway of beta‐amyloid release from neurons
Bibliographic record
Abstract
Abstract Background The endosomal‐lysosomal system has long been linked to the production of beta‐amyloid (Aβ), but the specific intracellular compartments involved in Aβ secretion remain contentious. Conventionally, lysosomes are associated with Aβ degradation, yet studies have also shown that lysosomes are a site of Aβ accumulation. Lysosomal exocytosis is a major secretory pathway in non‐neuronal cells, but few studies have investigated this pathway in neurons. This project examined the role and mechanism of lysosomal exocytosis in neurons, and we hypothesized that lysosomal exocytosis is a pathway for Aβ secretion from neurons. Methods We have established human iPSC‐derived neurons in culture, including cells bearing the APP Swedish mutation. Cells were transduced with pH sensitive fluorescent (pHluorin/pHmScarlet) tagged compartment markers to examine neurosecretory granules (synaptophysin), early endosomes (Rab5), late endosomes (Rab9) and lysosomes (LAMP1). Cells were loaded with fluorescent exogenous Aβ or Amytracker to label endogenous Aβ. We then stimulated secretion with ionomycin and used live cell Total Internal Reflection Fluorescence (TIRF) microscopy to examine molecular events occurring within 250 nm to the plasma membrane. shRNA against proteins known to be involved with lysosomal secretion (Rab27b, Munc13‐4 and synaptotagmin‐7) were used as controls. Imaris software was used to analyze the number and timing of lysosomal secretory events and the secretion of Aβ. Results As previously reported, exogenous Aβ in wild‐type cells and endogenous Aβ in APP Swedish cells accumulates in lysosomes, but not in early endosomes. TIRF microscopy captured videos of lysosomes approaching and fusing with the plasma membrane. Fusion appears as a reduction in normal fluorescent LAMP1 signal and an increase in pH sensitive fluorescent protein marker signal (reflecting the loss of luminal acidity due to fusion). Intracellular Aβ was released from neurons as lysosomes fused with the plasma membrane, seen as a simultaneous decrease in fluorescent Aβ labelling. Silencing of Rab27b significantly reduced lysosomal exocytosis and Aβ secretion, which confirmed that this is a lysosomal process. Conclusion Our results demonstrate that lysosomal exocytosis is a novel secretion pathway for Aβ in human neurons and identify potential pharmacological targets that regulate clearance of Aβ.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".