Involvement of cytosolic phospholipase A<sub>2</sub> alpha signalling pathway in spontaneous and transforming growth factor‐beta‐induced activation of rat hepatic stellate cells
Bibliographic record
Abstract
BACKGROUND: Hepatic stellate cells (HSCs) are extracellular matrix-producing cells that play a pivotal role in liver fibrogenesis. During liver injury and when cells are placed in vitro, HSCs undergo phenotypic transition from quiescent retinoid-storing cells to activated retinoid-deficient myofibroblast-like cells. Although several mediators including reactive oxygen species, platelet derived growth factor, transforming growth factor-beta (TGF-β) and tumour necrosis factor-alpha (TNF-α) were implicated in HSC activation, the cellular signalling pathways that regulate this process remain incompletely defined. AIMS: The objectives of this study were to evaluate the role of cytosolic phospholipase A(2) alpha (cPLA(2)α) and peroxisome proliferator-activated receptor-beta/delta (PPAR-β/δ) in HSC activation. METHODS: Rat HSCs were isolated, purified, cultured and stimulated with TGF-β1 in the presence or absence of the selective cPLA(2)α inhibitor, arachidonyltrifluoromethyl ketone (AACOCF(3)). The activation status of HSC was evaluated by immunofluorescent staining of alpha-smooth muscle actin (α-SMA) and by measuring the expression of cPLA(2)α, cyclooxygenase 2 (COX-2) and PPAR-β/δ using western blot analysis. RESULTS: Rapid and significant increase in cPLA(2)α expression was observed during activation of HSCs. These events preceded the elevation of PPAR-β/δ and the expression of α-SMA. Elevated expression of cPLA(2)α, but not COX-2, was also observed during TGF-β-induced HSC activation. The TGF-β-induced α-SMA expression was blocked by AACOCF(3). Furthermore, transfection of a cPLA(2)α expression vector enhanced the transcription activity of PPAR-β/δ and the expression of α-SMA in HSCs. CONCLUSION: cPLA(2)α-mediated induction of PPAR-β/δ is a novel intracellular signalling pathway in spontaneous and TGF-β induced activation of HSCs and could be a potential therapeutic target for the treatment of liver fibrosis.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".