Notice bibliographique
Résumé
Epithelia are layers of adherent cells that line the inner and outer surfaces of diverse tissues and organs throughout the body. Their main function is to separate body compartments, and to mediate transport of different substances between them. This is only possible because epithelial cells are ‘polar’ in the sense that their apical membranes (on the cell's outer surface) differ in protein composition from their basolateral membranes (on the inner surface). Many proteins of the apical or basolateral membranes have been recognized as important players in establishing cellular polarity, but the mechanisms that regulate epithelial polarization are still poorly understood. In a recent Nature paper a US/Canadian team of scientists led by Ulrich Tepass have genetically dissected some components of the underlying machinery which regulates epithelial polarity.The organization of epithelial cell membranes has been intensively studied in Drosophila embryos and several genes that function in epithelial polarity have been discovered. These genes include yrt, cora, Nrx-IV and ATPa, which encode the basolateral proteins Yurt, Coracle, Neurexin IV and the α-subunit of the Na+,K+-ATPase, respectively. To gain more insight into their functions in epithelial polarity, the scientists first generated transgenic flies, which were defective in one or two of the above genes. In a second step they assessed the effects on epithelial polarity by using antibodies to identify the locations of two proteins, ‘Crumbs’ and ‘Discs large’, which served as marker proteins for apical and basolateral membranes, respectively.When the team examined early Drosophila embryos that lacked the yrt gene, they observed that in addition to being found in the apical membrane, ‘Crumbs’ was mislocalized in the basolateral membrane, indicating that the Yurt protein is required for correct positioning of ‘Crumbs’ and epithelial polarity. In another type of mutant embryo, which lacked a functional yrt gene, but was provided with yrt mRNA to produce Yurt protein by the mother's follicle cells (surrounding the egg), mislocalization of ‘Crumbs’ was far less pronounced. Because the yrt gene was still expressed to some extent, the team could study genetic interactions between yrt and polarity genes that did not show mislocalization of ‘Crumbs’ when they were mutated individually.The scientists hypothesized that if they observe polarity defects in a double mutant, the deleted genes must be acting synergistically, suggesting that they function in the same pathway of epithelial cell differentiation. From six genes that they investigated in combination with yrt, they observed mislocalization of the ‘Crumbs’ protein in the yrt/ATPa, yrt/Nrx-IV and yrt/cora double mutants, suggesting functions for the Na+,K+-ATPase and Neurexin-IV in establishing epithelial polarity.Next they carefully analyzed the polarity phenotypes of the various mutants at different developmental stages. In doing so, the team provided genetic evidence that Yurt, Coracle, Neurexin-IV and the Na+,K+-ATPase are a new group of functionally cooperating proteins that are involved in establishing an epithelial cell's polarity, and the proteins seem to act in two partially overlapping pathways.Together, Tepass's team have provided evidence that epithelial polarity is controlled on multiple levels involving different protein complexes. Yurt seems to play a major role in this process. It appears that Yurt is a general core regulator of epithelial membrane organization, as this function is conserved even in mammalian cells.
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 | 0,004 | 0,003 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,003 | 0,001 |
| Bibliométrie | 0,003 | 0,002 |
| Études des sciences et des technologies | 0,002 | 0,013 |
| Communication savante | 0,010 | 0,019 |
| Science ouverte | 0,002 | 0,004 |
| Intégrité de la recherche | 0,006 | 0,015 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,007 | 0,003 |
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 ».