Divergent responses of <i>ras</i>-transfected and non-<i>ras</i>-transfected human keratinocytes to extracellular calcium
Bibliographic record
Abstract
Raising extracellular calcium (Ca o ) induces terminal differentiation in cultured epidermal keratinocytes. The introduction of the ras oncogene into keratinocytes results in resistance to Ca o -mediated differentiation. To understand the signaling mechanism involved, we examined the Ca o -induced formation of inositol triphosphate (IP 3 ) and changes in intracellular Ca 2+ (Ca i ) concentration in non-ras-transfected and ras-transfected HaCaT lines of human keratinocytes. When switched from 0.05- to 1.5-mM Ca o medium, the non-ras HaCaT line showed a rapid twofold increase in IP 3 formation, whereas the IP 3 level in the ras-transfected I-7 line was slightly affected. G-protein-coupled activation of phospholipase was intact in both lines, as evidenced by the generation of similar amounts of IP 3 in response to addition of bradykinin or guanosine 5'-[γ-thio]-triphosphate. Addition of 1.0 mM Ca o evoked similar Ca i responses in both non-ras- and ras-transfected cells: a transient elevation, followed by a sustained lower plateau. However, the two lines differed in their later responses: after being maintained in 1.0 mM Ca 2+ for 24 h, the Ca i level was significantly lower in ras-transfected cells than in non-ras-transfected HaCaT cells. The Ca o -induced increase in Ca i in both lines was inhibited by the Ca 2+ entry blocker SK&F 96365 or depolarization in high K + bathing solution, demonstrating its dependence of calcium influx. The results suggest fundamental differences in the early signal that are generated in response to an increase in Ca o in ras-transfected keratinocytes, with the absence of a Ca o -induced rise in IP 3 -a signaling pathway defect that may play a role in the differentiation block the cells exhibit. In addition, the inability of ras-transfected cells to sustain a prolonged Ca i plateau may also contribute to their inability to differentiate in response to the Ca o signal.Key words: cell differentiation, intracellular Ca 2+ , IP 3 , keratinocytes, ras transfection, signal transduction.
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How this classification was reachedexpand
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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".