Divergent Levels of CD112 and INKA1 Define a Subset of Human Hematopoietic Stem Cells That Resists Regenerative Stress to Preserve Stemness
Notice bibliographique
Résumé
The first insight into the complexity of post-transplant in vivo dynamics of hematopoietic stem cells (HSC) in humans was only recently showcased by examining longitudinal clonal contributions in gene therapy patients. Initial blood reconstitution was achieved by short-term (ST-)HSC, but in the longer-term hematopoiesis originated from long-term (LT-)HSC that only became recruited after a latency phase of 1-2 years (Scala et al 2018). Thus, deciphering the mechanisms governing how LT-HSC might resist transplant mediated activation and/or respond to the varying hematopoietic demands that occur during homeostasis would be an important goal for improving HSC cell therapies. We previously linked INKA1(=C3orf54/FAM212A) mediated PAK4 inhibition and reduced H4K16 acetylation (H4K16ac) to quiescence in human leukemia stem cells (Kaufmann, Blood 2019). Here, we interrogate the role of this signaling axis in normal human hematopoiesis. Immunostaining revealed distinct subsets defined by the dichotomy of INKA1 and H4K16ac within cord blood ST- and LT-HSC, mechanistically supported by BioID, chromatin fiber analysis and PLA data showing INKA1 interacting with the H4K16 deacetylase, SIRT1. Among quiescent LT-HSC, we found that the INKA1high fraction (~10 % of LT-HSC) had the lowest CDK6 levels and represented LT-HSC in an alternative state of quiescence. We then used protein interaction (BioID) data to show that a shared interactor of INKA1 and PAK4, CD112 could be used to sort for the subset of CD112low LT-HSC that was in this alternatively quiescent LT-HSC state (H4K16aclow, CDK6low, CellROXlow). Compared to primary cells, culture attenuates the strict dichotomy of INKA1 and H4K16ac but only in cells in which colocalization of PAK4 with both occurred, suggesting PAK4 interferes with SIRT1-INKA1 interaction thereby permitting H4K16 acetylation. In vitro time course analysis showed that H4K16ac and PAK4 levels preceded the upregulation of the G0-exit marker CDK6 implicating a role in cell cycle priming. Pseudo-time scRNAseq analysis for INKA1high versus PAK4high, CDK6high and CD112high expression in mobilized peripheral blood (modeling in vivo HSC activation) showed enrichment of early or late diffusion indicative of quiescent versus primed cell status, respectively. Strikingly, in xenograft assays CD112low LT-HSC exhibited delayed engraftment kinetics with higher secondary repopulation capacity than faster repopulating CD112high LT-HSC reflecting the subset of LT-HSC that resist early activation. Similarly, INKA1-OE or PAK4 knock-down in vivo resulted in an early restraint in engraftment levels (@4 w), whereas 20 w engraftment reached control levels. When measured in secondary transplant assays the HSC frequency was 4 to 8-fold higher in the groups that showed this early restraint. Thus, resisting early activation (latency) preserves the regenerative potential of such HSC. In vivo 5-Fluorouracil treatment at week 4 accelerated latency exit and further increased HSC frequency of INKA1-OE cells while abolishing serial transplantation potential of controls. Hence, the induction of proliferative stress via creating acute hematopoietic demand is able to lift the INKA1-OE imposed restraint resulting in increased hematopoietic output while also promoting HSC self-renewal. Collectively, our data decipher the molecular intricacies underlying HSC heterogeneity and self-renewal regulation and point to latency as an orchestrated physiological response that integrates quiescence control with HSC fate choices to preserve a stem cell reservoir. Disclosures Takayanagi: Kirin Holdings Company, Ltd: Current Employment. Dick:Bristol-Myers Squibb/Celgene: Research Funding.
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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 | 0,001 | 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 | 0,001 |
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 ».