An ABCA1-independent pathway for recycling a poorly lipidated 8.1 nm apolipoprotein E particle from glia
Bibliographic record
Abstract
Lipid transport in the brain is coordinated by glial-derived lipoproteins that contain apolipoprotein E (apoE) as their primary protein. Here we show that apoE is secreted from wild-type (WT) primary murine mixed glia as nascent lipoprotein subspecies ranging from 7.5 to 17 nm in diameter. Negative-staining electron microscropy (EM) revealed rouleaux, suggesting a discoidal structure. Potassium bromide (KBr) density gradient ultracentrifugation showed that all subspecies, except an 8.1 nm particle, were lipidated. Glia lacking the cholesterol transporter ABCA1 secreted only 8.1 nm particles, which were poorly lipidated and nondiscoidal but could accept lipids to form the full repertoire of WT apoE particles. Receptor-associated-protein (RAP)-mediated inhibition of apoE receptor function blocked appearance of the 8.1 nm species, suggesting that this particle may arise through apoE recycling. Selective deletion of the LDL receptor (LDLR) reduced the level of 8.1 nm particle production by approximately 90%, suggesting that apoE is preferentially recycled through the LDLR. Finally, apoA-I stimulated secretion of 8.1 nm particles in a dose-dependent manner. These results suggest that nascent glial apoE lipoproteins are secreted through multiple pathways and that a greater understanding of these mechanisms may be relevant to several neurological disorders.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".