Growth Factor Independence 1 (Gfi1) Regulates Cell-Fate Decision of the Bipotential Granulocytic-Monocytic Precursors Defined by Expression of CD48 As a New Marker,
Notice bibliographique
Résumé
Abstract Abstract 3217 Gfi1 regulates the expression of genes important for survival, proliferation and differentiation of hematopoietic cells and is required for normal multi-lineage blood cell development. Mutations affecting the function of Gfi1 are implicated in leukemia, lymphoma, auto-immune disease and neutropenia. Gfi1 deficient mice are severely neutropenic and accumulate an aberrant CD11b+GR1int myeloid population, which was assumed to contain precursors either arrested in granulocytic differentiation or redirected into the monocytic lineage. To further analyze the function of Gfi1 during granulopoiesis, we used bone marrow cells from Gfi1-GFP knock-in mice, which enable to follow Gfi1 expression by simply measuring green fluorescence. By this, we found that the CD11b+GR1lo bone marrow fraction that contains monocytes separates into two populations expressing low or high Gfi1. We FACS-sorted these two subsets (CD11b+GR1loGfi1hi and CD11b+GR1loGfi1lo) and observed that, 99% of CD11b+GR1loGfi1lo cells resembled monocytes, while over 90% of the CD11b+GR1loGfi1hi cells were myelocytes or metamyelocytes. After three days in culture in the presence of GM-CSF, almost all CD11b+GR1loGfi1lo cells developed into adhering macrophages, while 73% of the CD11b+GR1loGfi1hi cells developed into mature neutrophils, suggesting that Gfi1 expression drives myeloid precursors into the granulocytic lineage. We determined the genome-wide expression patterns of these two populations and as a control also of CD11b+GR1+ granulocytes and the aberrant CD11b+GR1int population found in Gfi1−/− mice (termed: CD11b+GR1loGfi1−/−). Unsupervised clustering analysis showed that CD11b+GR1loGfi1−/− cells are similar to CD11b+GR1loGfi1lo monocytes, while CD11b+GR1loGfi1hi cells are more closely related to mature granulocytes (CD11b+GR1hi). Gene-Set enrichment analysis (GSEA) revealed that genes associated with cell cycle progression were up regulated in CD11b+GR1loGfi1hi, while genes controlling the humoral immune response and chemokine receptor signaling activity were downregulated. Promoter analysis of differentially expressed genes showed for CD11b+GR1loGfi1hi an over-representation of binding sites for E2F, a regulator of cell cycle genes, and for CD11b+GR1loGfi1lo cells an over-representation of binding sites for STAT5, a transcription factor required for monocyte development. The comparison of CD11b+GR1loGfi1hi cells with granulocytes also showed a higher expression of cell cycle associated genes and a lower expression of humoral immune response genes. This indicated that CD11b+GR1loGfi1hi cells show features of faster cycling, less differentiated precursor cells compared to monocytes (CD11b+GR1loGfi1lo) and granulocytes (CD11b+GR1hi). It is thus likely that CD11b+GR1loGfi1hi monocyte bone marrow subset contains the precursors committed to granulocytic differentiation. The unsupervised clustering analysis also revealed that CD48, a 40–45 kD cell surface glycoprotein, is inversely correlated to the Gfi1 expression and might enable to differentiate between CD11b+GR1loGfi1hi and CD11b+GR1loGfi1lo cells and to find a definition for precursors committed for granulopoiesis. We found that CD48 can replace Gfi1/GFP as well as CD11b in a flow cytometric analysis and using GR1, CD48 staining only, we were able to clearly separate granulocytic precursors from other monocytic cells and mature granulocytes as shown by Wright-Giemsa staining and in vitro culture of sorted cells in the presence of M-CSF or GM-CSF. GR1loCD48hi cells gave rise to adherent macrophages in the presence of M-CSF but generated monocytes and granulocytes in the presence of GM-CSF, while GR1loCD48lo cells can only develop into granulocytes in the presence of GM-CSF. Thus CD48 allowed the separation of bipotential precursors from other precursors that are fully committed to granulopoiesis. Analysis of Gfi1−/− bone marrow cells using the GR1, CD48 markers clearly showed that the aberrant CD11b+Gr1int population represents regular monocytes that accumulated at the expense of granulocytes. This suggests that Gfi1 regulates cell-fate decision in bipotential granulocytic-monocytic precursors, which can be precisely defined by expression of GR1 and CD48. This allows for the first time a more precise definition of monocytic-, granulocytic and bipotential precursors in mice on a phenotypic basis. Disclosures: Duehrsen: Alexion: Honoraria.
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 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
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 ».