Phospholipid metabolism in the MCF-7 cell cycle, regulation of phosphatidylcholine accumulation
Notice bibliographique
Résumé
Cells reproduce by duplicating their components, doubling their size and dividing in two. Since phospholipids are major components of cell membranes, cells must double their phospholipid mass so that the daughter cells formed have the same membrane composition as the parent. However, the mode of phospholipid accumulation and how this is regulated within the cell cycle remained largely unknown. The objective of this project is to investigate how membrane phospholipid accumulation is coordinated and regulated in the cell cycle, with special emphasis on the accumulation of phosphatidylcholine (PC). Two synchronization protocols were developed that synchronized approximately 90% of the cells at specific points in the cell cycle. The double hydroxyurea treatment synchronized MCF-7 cells at the G1/S boundary while the combination of hydroxyurea and nocodazole blocked the cells at mitosis. Synchronized cells at different stages of the cell cycle were obtained by harvesting cells at various times after removal of the cell cycle blocking agents. Measurement of phospholipid mass at different stages of the cell cycle revealed that the contents of PC, phosphatidylethanolamine (PE) and phosphatidylinositol (PI) declined during S phase followed by a net accumulation in G2/M phase. The relative composition of PC, PE and PI remained unchanged throughout the cell cycle, suggesting that the e might be coordinated metabolism of these lipids in the cell cycle. Further studies demonstrated that the rate of incorporation of [3H]choline into PC was low in early S phase, increased from late S and throughout G2/M. The fluxes in PC synthesis correlated with changes in the activities of CTP:phosphocholine cytidylyltransferase (PCCT), cholinephosphotransferase (CPT) and the levels of membrane-associated PCCT. The results suggest that PC synthesis contributes to the fluctuation in PC levels observed during the MCF-7 cell cycle. On the other hand, there was little change in the rate of incorporation of [14C]ethanolamine into PE during S and G2/M phases. The activity of CTP:phosphoethanolamine cytidylyltransferase (PECT), the rate limiting enzyme in PE synthesis, showed little variation in the cell cycle, suggesting that the rate of PE catabolism is the dominant factor in regulating PE levels during the cell cycle. No evidence was obtained to implicate changes in cellular CTP levels in the cell cycle regulation of phospholipid synthesis. Studies on PC catabolism revealed that the rate of PC catabolism was enhanced during S phase but terminated in the G2/M phase. Taken together, our studies demonstrated that the decrease in PC content during S phase resulted from enhanced PC catabolism, while PC accumulation in G2/M was attributed to both enhanced PC biosynthesis and cessation of PC catabolism.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».