Physiological and coordinate downregulation of the NPC1 and NPC2 genes are associated with the sequestration of LDL‐derived cholesterol within endocytic compartments
Bibliographic record
Abstract
The Niemann-Pick C1 and C2 (NPC1 and NPC2) proteins have a central role in regulating the transport of lipoprotein-derived cholesterol from endocytic compartments to the endoplasmic reticulum for esterification by acyl-CoA:cholesterol acyltransferase (ACAT) and feedback inhibition of the sterol regulatory element-binding protein (SREBP) pathway. Since the NPC1 gene/protein has recently been shown to be downregulated by feedback inhibition of the SREBP pathway, the present study was performed to determine whether physiological downregulation of the NPC1 gene/protein alters the transport and metabolism of low-density lipoprotein (LDL)-derived cholesterol in human fibroblasts. To perform this study, three different culture conditions were used that included fibroblasts grown in lipoprotein-deficient serum (LPDS), LPDS supplemented with LDL, and LPDS supplemented with LDL, followed by equilibration in the absence of LDL to allow the transport of LDL-derived cholesterol from endocytic compartments and equilibration of cellular sterol pools. The results from this study indicated that in addition to the NPC1 gene/protein, the NPC2 gene/protein was also downregulated by LDL-derived cholesterol-dependent feedback inhibition and that downregulation of both the NPC1 and NPC2 genes/proteins was associated with the sequestration of LDL-derived cholesterol within endocytic compartments, including late endosomes/lysosomes after equilibration. Therefore, it is proposed that physiological and coordinate downregulation of the NPC1 and NPC2 genes/proteins promotes the sequestration of LDL-derived cholesterol within endocytic compartments and serves a role in maintaining intracellular cholesterol homeostasis.
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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 | 0.000 | 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".