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Aging Decline of LEPR+ HSCs

ABSTRACT: Leptin receptor (LEPR) identifies a subpopulation of hematopoietic stem cells (HSCs) with high repopulating potential. In this study, we demonstrated that LEPR-expressing HSCs while exhibiting significantly higher engrafting potential and self-renewing capacity in young mice showed early age-associated decline in these functions as compared to the LEPR- HSCs. LEPR+ HSCs have transcriptomic profiles significantly different from LEPR- HSCs in young mouse bone marrow, but middle-aged HSCs do not have distinct transcriptomic profiles based on LEPR status. The age-related phenotypes were associated with a proinflammatory transcriptomic profile at baseline in young LEPR+ HSCs, which was further exacerbated by age. In contrast, LEPR- HSCs did not show age-associated functional impairment at the ages tested. This suggested that subsets of HSCs are susceptible to age-related decline in function at varying ages and that LEPR+ HSCs are a potential target for early cellular therapeutic interventions in delaying the detrimental effects of aging in hematopoiesis.

ORGANISM(S): Mus musculus

PROVIDER: GSE221126 | GEO | 2023/02/18

REPOSITORIES: GEO

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Project description:Leptin receptors (Lepr) are expressed by various types of stem cells including mesenchymal stem cells, hematopoietic stem cells, embryonic stem cells, and induced pluripotent stem cells. Leptin/lepr signaling is also a central regulator of metabolism. However, the role of Lepr in pluripotency, metabolic disease progression and growth development is still controversial and poorly understood. In the present study, we explored the Lepr function in disease progression, pluripotency and metabolism using day 14.5 mouse embryonic fibroblasts (MEFs) and their reprogrammed induced pluripotent stem cells (iPSCs) as model system. We successfully reprogrammed mouse embryonic fibroblasts into iPSCs from control and db/db (Lepr deficient) mice. Using a global quantitative proteomic approach, we identified key pathways regulating pluripotency, metabolic homeostasis and protein synthesis during fetal growth and development. The Lepr MEFs show abnormal metabolic abnormalities and mitochondrial dysfunction as compared to control MEFs, while Lepr iPSCs show upregulated elongated factor 4 e (eIF4e) protein synthesis pathway and altered Oct4 and Stat3 pathways which are involved in normal fetal growth development. Furthermore, chip analysis revealed that higher Stat3 binding on the promoter of eIF4e in Lepr iPSCs leads to higher protein synthesis in these cell types as compared to control iPSCs. Finally, point mutation corrected Lepr iPSCs using CRISPR/Cas9 gene editing method showed recovered pluripotency, metabolic and protein synthesis pathways. In conclusion, we have shown that Lepr signaling is involved in the regulation of the metabolic properties and key developmental pathways in MEFs and stemness of pluripotent stem cells. Disruption of Lepr signaling has been shown to involve in the pathophysiology of various diseases including obesity and diabetes. The generated MEFs and iPSCs in this present study provide valuable tools to explore the role of Lepr in the progression of obesity, diabetes and metabolic abnormalities, and to find the putative targets of Lepr signaling during the development of these diseases.

Project description:Decline in hematopoietic function in aged individuals is associated with expansion of phenotypic hematopoietic stem cells (HSCs) and a shift in their lineage potential toward production of myeloid cells. Both HSC-intrinsic changes, and extrinsic changes in the bone marrow (BM) microenvironment, have been identified in old mice and humans. However, to extend healthy and robust hematopoietic function from youth into older age, we need to understand and effectively target the processes that initiate functional hematopoietic decline. We recently identified decline in Insulin-Like Growth Factor 1 (IGF1) in the BM microenvironment as early as middle age to be an HSC-extrinsic initiating driver of HSC aging (Young et al., Cell Stem Cell 2021). As systemic IGF1 administration has significant undesirable side effects, we sought to comprehensively interrogate the cell population(s) in the BM microenvironment that are responsible for IGF1 decline, towards the goal of cell type-specific targeted therapy. We performed single cell RNA-seq to comprehensively profile hematopoietic and non-hematopoietic fractions of the BM in young (2-4mo; n = 5 biological replicates) and middle-aged (12-14mo; n = 10) mice. In young mice, we find Igf1 to be nearly entirely detected in the mesenchymal stromal cell populations Adipo-CAR and Osteo-CAR, and Igf1 is significantly reduced in expression in both populations in middle-aged mice. Using two independent mesenchymal stromal cell Cre mouse lines, Lepr-Cre and Prx1-CreERT2, we found that knockout of Igf1 resulted in myeloid-biased hematopoiesis that replicated aging phenotypes. This result was similar to our published work showing that knockout of Igf1 using Nestin-CreER causes myeloid-biased hematopoiesis. While these Cre models generally do not mark similar cell types, it has been shown that Lepr-Cre-expressing perisinusoidal stromal cells include cells that express certain Nestin transgenes. Using fluorescent reporters, we find that all three lines (Lepr-Cre, Prx1-CreERT2, and Nestin-CreER) overlap in expression in the CAR populations that abundantly express Igf1 in young mice. Taken together, our work identifies a new role for Cxcl12-abundant reticular cells in sustaining hematopoietic function through local IGF1 production and suggests that specifically targeting CAR cells to maintain or restore Igf1 expression during aging will have beneficial effects on lymphoid cell production and adaptive immunity.

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Aging Decline of LEPR+ HSCs

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