Report Epithelial Polarity Proteins Regulate Drosophila Tracheal Tube Size in Parallel to the Luminal Matrix Pathway
Bibliographic record
Abstract
Department of Cell and Systems Biology, University ofToronto, Toronto, ON M5S 3G5, CanadaSummaryRegulationofepithelialtubesizeiscriticalfororganfunction.However,themechanismsoftubesizecontrolremainpoorlyunderstood. In the Drosophila trachea, tube dimensions areregulated by a luminal extracellular matrix (ECM) [1–4].ECM organization requires apical (luminal) secretion of theproteinVermiform (Verm),which depends onthebasolateralseptate junction(SJ) [5,6].Here,weshow thatapical andba-solateral epithelial polarity proteins interact to controltracheal tube size independently of the Verm pathway. Muta-tionsinyurt(yrt)andscribble(scrib),whichencodeSJ-asso-ciatedpolarityproteins[7,8],causeanexpansionoftrachealtubesbutdonotdisruptVermsecretion.Reducingactivityofthe apical polarity protein Crumbs (Crb) suppresses thelength defects in yrt but not scrib mutants, suggesting thatYrt acts by negatively regulating Crb. Conversely, Crb over-expression increases tracheal tube dimensions. Reducingcrb dosage also rescues tracheal size defects caused bymutationsincoracle(cora),whichencodesanSJ-associatedpolarity protein [8, 9]. In addition, crb mutations suppresscora length defects without restoring Verm secretion.Together, these data indicate that Yrt, Cora, Crb, and Scriboperate independently of the Verm pathway. Our datasupport a model in which Cora and Yrt act through Crb toregulate epithelial tube size.Results and DiscussionYrt Is Essential for Tracheal Tube Size Control but Is NotRequired for Vermiform and Serpentine SecretionThe transmembrane protein Crumbs (Crb) acts as an apicaldeterminant during establishment of epithelial apical-basalpolarity[10,11].Duringlaterstagesofepithelialdifferentiation,Crb promotes apical membrane growth independently of itsrole in apical-basal polarity [12]. Crb activity is counteractedby different groups of basolateral polarity proteins includingthe Yrt/Cora group, which is composed of Yurt (Yrt), Coracle(Cora), Na
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".