Cholesterol Trafficking for Steroid Biosynthesis in MA‐10 Mouse Tumor Leydig Cells
Bibliographic record
Abstract
The hormone‐sensitive and rate‐limiting step in steroid biosynthesis is the movement of cholesterol from intracellular sources to the inner mitochondrial membrane (IMM). Despite the numerous studies on cholesterol trafficking in steroidogenesis, the exact source and mechanism by which cholesterol is transported to IMM remains to be elucidated. D4 is the fourth domain of perfringolysin O protein, which has the ability to bind membranes containing greater than 30 mol% cholesterol of total lipid concentration with high affinity. mCherry‐tagged D4 was used to visualize cholesterol trafficking in MA‐10 cells. Confocal microscopy showed D4‐mCherry localized at the plasma membrane, but upon 45 minutes treatment with dibutyryl‐cAMP (dbcAMP) a significant reduction in plasma membrane labeling was observed. Functional inhibitors of proteins involved in cholesterol import into mitochondria and metabolism, blocked steroid formation and slowed down the movement of D4‐mCherry from the plasma membrane. Recombinant D4‐GFP protein readily bound the outer leaflet of the plasma membrane even after 120 minutes of dbcAMP stimulation, indicating that cholesterol was trafficked from the inner leaflet of the plasma membrane. D4‐mCherry also localized the late endosomes upon dbcAMP stimulation suggesting a route for the cholesterol from plasma membrane to mitochondria. These data suggest that the bulk of the steroidogenic pool of cholesterol, mobilized by cAMP for acute steroidogenesis, likely originates from the inner leaflet of the plasma membrane. Source: CIHR
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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 | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.003 |
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".