Activity of lumacaftor is not conserved in zebrafish Cftr bearing the major cystic fibrosis‐causing mutation
Bibliographic record
Abstract
Abstract F508del‐cystic fibrosis transmembrane conductance regulator (CFTR) is the major mutant responsible for cystic fibrosis (CF). ORKAMBI ® , approved for patients bearing this mutant, contains lumacaftor (VX‐809) that partially corrects F508del‐CFTR's processing defect and ivacaftor (VX‐770) that potentiates its defective channel activity. Unfortunately, the clinical efficacy of ORKAMBI ® is modest, highlighting the need to understand how the small molecules work so that superior compounds can be developed. Because, human CFTR (hCFTR) and zebrafish Cftr (zCftr) are structurally conserved as determined in recent cryo‐EM structural models, we hypothesized that the consequences of the major mutation and small molecule modulators would be similar for the two species of protein. As expected, like the F508del mutation in hCFTR, the homologous mutation in zCftr (F507del) is misprocessed, yet not as severely as the human mutant and this defect was restored by low‐temperature (27°C) culture conditions. After rescue to the cell surface, F507del‐zCftr exhibited regulated channel activity that was potentiated by ivacaftor. Surprisingly, lumacaftor failed to rescue misprocessing of the F507del‐zCftr at either 37 or 27°C suggesting that future comparative studies with F508del‐hCFTR would provide insight into its structure: function relationships. Interestingly, the robust rescue of F508del‐zCftr at 27°C and availability of methods for in vivo screening in zebrafish present the opportunity to define the cellular pathways underlying rescue.
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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 | 0.000 | 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) | 0.002 | 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".