Phosphoinositide 3-Kinase γ–Deficient Mice Are Protected From Isoproterenol-Induced Heart Failure
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Bibliographic record
Abstract
BACKGROUND: We have recently shown that genetic inactivation of phosphoinositide 3-kinase gamma (PI3Kgamma), the isoform linked to G-protein-coupled receptors, results in increased cardiac contractility with no effect on basal cell size. Signaling via the G-protein-coupled beta-adrenergic receptors has been implicated in cardiac hypertrophy and heart failure, suggesting that PI3Kgamma might play a role in the pathogenesis of heart disease. METHODS AND RESULTS: To determine the role for PI3Kgamma in hypertrophy induced by G-protein-coupled receptors and cardiomyopathy, we infused isoproterenol, a beta-adrenergic receptor agonist, into PI3Kgamma-deficient mice. Compared with controls, isoproterenol infusion in PI3Kgamma-deficient mice resulted in an attenuated cardiac hypertrophic response and markedly reduced interstitial fibrosis. Intriguingly, chronic beta-adrenergic receptor stimulation triggered impaired heart functions in wild-type mice, whereas PI3Kgamma-deficient mice retained their increased heart function and did not develop heart failure. The lack of PI3Kgamma attenuated the activation of Akt/protein kinase B and extracellular signal-regulated kinase 1/2 signaling pathways in cardiac myocytes in response to isoproterenol. beta1- and beta2-adrenergic receptor densities were decreased by similar amounts in PI3Kgamma-deficient and control mice, suggesting that PI3Kgamma isoform plays no role in the downregulation of beta-adrenergic receptors after chronic beta-adrenergic stimulation. CONCLUSIONS: Our data show that PI3Kgamma is critical for the induction of hypertrophy, fibrosis, and cardiac dysfunction function in response to beta-adrenergic receptor stimulation in vivo. Thus, PI3Kgamma may represent a novel therapeutic target for the treatment of decreased cardiac function in heart failure.
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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) | 0.000 | 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 it