New Candidate Regulators of Hematopoietic Stem Cells Identified from Transcriptional Comparisons of Highly Purified Populations of Longterm Repopulating Cells with Markedly Different in Vivo Self-Renewal Activities
Notice bibliographique
Résumé
Abstract Significant advances have been made in the development of methods for purifying murine hematopoietic cells with longterm (>4 months) in vivo reconstituting ability although these longterm repopulating cells (LTRCs) remain heterogeneous with regard to the self-renewal (SR) activity they display when transplanted into irradiated hosts. Furthermore our group has also identified cell culture conditions that differentially alter LTRC activity without immediate effects on their proliferation or survival. Here, we show that highly purified LTRCs with high and low SR properties can be prospectively isolated from normal adult mouse bone marrow (ABM) as 2 separate populations according to their expression of CD150 within the EPCR++CD48−CD45mid fraction of cells: 56% total LTRCs and 43% of the high SR type in the CD150+ subset vs. 39% total LTRCs and 32% of the low SR type in the CD150− subset (as determined from 62 and 28 single cell transplants, respectively). As a first test of whether these populations would likely be useful to search for new molecular differences associated with their different SR properties, we compared the level of expression in these 2 populations of a small set of genes previously reported to regulate LTRC SR activity: c-Kit, Bmi1, Gata3, Rae28, Ezh2 and Lnk by quantitative real-time PCR (Q-RT-PCR). This exercise revealed transcript levels of the first 4 of these genes to be significantly higher in the CD150+ subset that is selectively enriched in high SR LTRCs, thus validating the concept that they have a distinct molecular signature. Previous evidence shows that high SR LTRCs are present in both FL LTRCs and ABM LTRCs but they differ in some properties (i.e.: cell cycle status, regeneration kinetics). We therefore began a search for ontogeny-independent components of the SR machinery by comparing tags present in 2 LongSAGE libraries produced from CD45midlin−Rho−SP ABM cells and from lin−Sca1+CD43+Mac1+ embryonic day 14.5 fetal liver (FL) cells (each 20–30% total LTRCs and 12–20% of the high SR type, as determined by 132 (FL) and 352 (ABM) single cell transplants, respectively). From these comparisons and additional data in other publicly available datasets for primitive murine hematopoietic cells, we identified 28 genes not previously shown to have a functional role in LTRC SR control. We then compared the level of expression of these 28 genes between the CD150+ subsets of EPCR++CD48−CD45mid ABM cells and FL cells (24% total LTRCs and 12% high SR LTRCs in the FL subset) and their respective downstream lin− progeny. This comparison revealed 10 of these genes to be down-regulated in the lin− populations of both ABM and FL. Further comparison of the expression of these 10 genes between the high vs. low SR LTRCs (found in the CD150+ and CD150− subsets of EPCR++CD48−CD45mid) ABM cells showed the expression of 5 (Vwf, Rhob, Pld3, Prnp and Smarcc2) to be downregulated in the CD150− (low SR LTRC) subset. Interestingly, the first 4 of these genes, as well as 2 of the preliminary set of SR regulators (Bmi1 and Gata3), were also selectively down-regulated in EPCR++CD150+CD48−CD45mid ABM cells that had been incubated for 16 hours in 1 or 10 ng/ml Steel factor + 20 ng/ml IL-11 (conditions that decrease LTRC activity in vivo 4–5-fold before any of these divide or die). Taken together, these results point to the existence of more, although a rather small number of additional genes, including Vwf, Rhob, Pld3, and Prnp, whose products may be involved in controlling the SR potential of normal mouse LTRCs.
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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) | 0,002 | 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 ».