Project description:Declining immune function with age is associated with reduced lymphoid output of hematopoietic stem cells (HSCs). Currently, there is poor understanding of the dynamic changes with age in the heterogeneous multipotent hematopoietic progenitor cell compartment, which regulates output of differentiated lymphoid cells. In this study, we observed progressive and specific loss of lymphoid-primed multipotent progenitor cells (LMPP/MPP4) as young animals began to age. Single cell RNA-seq revealed a concomitant increase in cycling of these progenitors with loss of a lymphoid priming signature. To interrogate functional multipotency of single cells, we developed a novel, feeder-free in vitro assay to concurrently assess lymphoid and myeloid potential. This assay revealed altered clonal composition of the LMPP/MPP4 compartment with aging, where progenitors with B cell and macrophage-restricted potential are lost while functionally multipotent progenitors are preserved. These results pinpoint an age and cellular compartment to focus further interrogation of the drivers of lymphoid cell loss with aging.
Project description:Declining immune function with age is associated with reduced lymphoid output of hematopoietic stem cells (HSCs). Currently, there is poor understanding of the dynamic changes with age in the heterogeneous multipotent hematopoietic progenitor cell compartment, which regulates output of differentiated lymphoid cells. In this study, we observed progressive and specific loss of lymphoid-primed multipotent progenitor cells (LMPP/MPP4) as young animals began to age. Single cell RNA-seq revealed a concomitant increase in cycling of these progenitors with loss of a lymphoid priming signature. To interrogate functional multipotency of single cells, we developed a novel, feeder-free in vitro assay to concurrently assess lymphoid and myeloid potential. This assay revealed altered clonal composition of the LMPP/MPP4 compartment with aging, where progenitors with B cell and macrophage-restricted potential are lost while functionally multipotent progenitors are preserved. These results pinpoint an age and cellular compartment to focus further interrogation of the drivers of lymphoid cell loss with aging.
Project description:Regulation of lineage potential and transcriptional priming by Ikaros. New insight is provided into a bivalent regulation of lineage priming in the HSC and its lympho-myeloid restricted progeny the LMPP by the lymphoid lineage-determining factor Ikaros; Whereas Ikaros is responsible for the activation of a cascade of lymphoid expression programs and for the establishment of lymphoid potential from the HSC to the LMPP it is also responsible for the repression of stem cell and erythroid genetic programs that are incompatible with further lineage restrictions emanating from the LMPP Experiment Overall Design: Ikaros null versus wt
Project description:Natural killer (NK) cells represent one of three lymphoid lineages and play a vital role in controlling viral infections and cancer. In contrast to B and T lymphopoiesis where cellular and regulatory pathways have been extensively characterized, the cellular stages of early human NK-cell commitment remain poorly understood Here we described a novel NK-lineage restricted progenitor (NKP) in fetal development, umbilical cord blood and adult bone marrow. We used microarrays to detail the global programme of gene expression genes of this new progenitor. Global gene expression analysis was performed on the NKP, multipotent progenitors LMPP, common lymphoid progenitor candidate and mature NK cells purified from Cord blood CD34+ cells (3-4 replicates, 2 experiments)
Project description:Regulation of lineage potential and transcriptional priming by Ikaros. New insight is provided into a bivalent regulation of lineage priming in the HSC and its lympho-myeloid restricted progeny the LMPP by the lymphoid lineage-determining factor Ikaros Whereas Ikaros is responsible for the activation of a cascade of lymphoid expression programs and for the establishment of lymphoid potential from the HSC to the LMPP it is also responsible for the repression of stem cell and erythroid genetic programs that are incompatible with further lineage restrictions emanating from the LMPP Keywords: Ikaros null versus wt
Project description:All lymphocytes are thought to develop from common lymphoid progenitors (CLPs). However, lymphoid-primed multi-potent progenitors (LMPPs) are more efficient than CLPs in differentiating into T cells and group 2 innate lymphoid cells (ILC2s). Here, we have divided LMPPs into CD127− (LMPP-s) and CD127+ (LMPP+s) subsets and compared them with Ly6D− and Ly6D+ CLPs. Adult LMPP+s differentiated into T cells and ILCs more rapidly and efficiently than other progenitors in transplantation assays. The development of T cells and ILC2s is highly active in the neonatal period. Neonatal CLPs are rare and, unlike prominent neonatal LMPP+s, do not efficiently differentiate into T cells and ILC2s. ILC2s generated in the neonatal period are long-lived and persist in adult tissues. These results suggest that some ILCs and T cells may develop from LMPP+s via CLP-independent pathways.
Project description:Bivalency has been postulated to be a ‘poised’ state from which removal of one or the other mark permits gene activation or repression. To determine whether gene expression changes accompanied resolution of bivalent genes, we first obtained the expression pattern of hematopoietic stem cells (HSC), lymphoid-primed multipotent progenitors (LMPP), common lymphoid progenitors (CLP) , early thymic precursors (ETP), double negative 2 (DN2) and double negative 3 (DN3) cells using Affymetrix arrays. Consistent with trends noted in earlier studies, K4+ genes were, on average, expressed at higher levels compared to K4+K27+ or K27+ genes in all subsets.
