Smaddening Complexity: The Role of Smad3 in Epithelial-Myofibroblast Transition
Why this work is in the frame
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Bibliographic record
Abstract
Epithelial-mesenchymal transition (EMT) has emerged as a major mechanism in the pathogenesis of organ fibrosis. The epithelium has been proposed to be a significant source of matrix-producing fibroblasts and of myofibroblasts (MFs), a motile and contractile cell type hallmarked by the expression of α-smooth muscle actin (SMA). Importantly, tissue accumulation of MFs shows strong correlation with the severity and progression of fibrotic diseases. The pleiotropic cytokine transforming growth factor-β(1) has been long known as the chief inducer of fibrosis, EMT and MF generation. Accordingly, receptor Smads (Smad2 and particularly Smad3), the direct targets of the activated transforming growth factor-β receptor have been implicated as critical mediators in fibrogenesis and EMT. However, evidence is accumulating that the role of Smad3 is complex and apparently controversial; in fact, Smad3 may differentially affect the various components of EMT, including the loss of epithelial markers (de-epithelialization), the production of extracellular matrix (fibrogenesis) and the expression of SMA (myogenic program). In this review, we revisit the role of Smad3 in epithelial-myofibroblast transition (EMyT). We first summarize the evidence supporting the thesis that Smad3 is a key mediator of EMT and MF generation; next, we present evidence supporting the antithesis that Smad3 is in fact a negative regulator of SMA expression and the activation of the myogenic program in the epithelium; finally, we propose a synthesis, which depicts Smad3 as a timekeeper and context-dependent modulator of EMyT. We suggest that EMyT is composed of an early, mesenchymal, Smad3-promoted phase and a late, myogenic, Smad3-inhibitable phase.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it