Widespread Growth Factor Expression in the Reptilian Epidermis Indicates Roles During Homeostasis and Wound Healing
Bibliographic record
Abstract
The skin is the primary interface between an organism and its external environment. As such, it participates in the maintenance of homeostasis, as well as functions as a physical barrier, protecting against physical trauma, solar radiation, and pathogens. These functions are mediated, at least in part, by various growth factors, including members of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and transforming growth factor β (TGFβ) families. Although growth factors have long been documented in the dermis, particularly during wound healing, less is known about their expression in the overlying epidermis. Here we performed a spatio‐temporal investigation of growth factor expression within the epidermis of a representative reptile, the leopard gecko ( Eublepharis macularius ). Recent work has demonstrated that leopard gecko skin has an intrinsic capacity to heal scar‐free. Therefore, we investigated the pattern of growth factor expression before, during, and after scar‐free wound healing. We demonstrate that the gecko epidermis expresses a diverse panel of growth factor ligands and receptors, including VEGF, VEGF receptors 1 (VEGFR1) and 2 (VEGFR2), FGF‐2 and FGFR1, and TGFβ1 and activin βA. Curiously, only VEGFR1 and FGFR1 were dynamically expressed, and only during the earliest phases of re‐epithelization; otherwise all the proteins of interest were constitutively present. Using double‐immunofluorescence, we observed co‐localization and/or overlapping expression patterns of VEGF/VEGFR2/VEGFR1 and FGF‐2/FGFR1. These findings indicate that homeostatic and injury‐mediated functions of the epidermis may involve both paracrine and autocrine signalling. Furthermore, they provide compelling evidence that keratinocytes expressing these growth factors may participate in non‐angiogenic roles during homeostasis. We propose that constitutive growth factor expression by keratinocytes is associated with functions specific to reptilian biology, including body‐wide skin shedding, protection against ultraviolet photodamage, and photobiosynthesis of vitamin D. Support or Funding Information Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants 400358 (to MV) and 401013 (to JP), and Ontario Veterinary College Scholarship (to NS)
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".