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Distinct TNF Receptors Dictate Stem Cell Fitness Versus Lineage Output in Clonal Hematopoiesis of Aging

ABSTRACT: Clonal hematopoiesis of aging results from enhanced fitness of mutant hematopoietic stem cells (HSCs) and associates with both favorable and unfavorable health outcomes related to lineage cell types produced by mutant HSCs. The extent to which lineage output can be controlled in clonal hematopoiesis is unknown. Using a mouse model of DNMT3AR882/+ clonal hematopoiesis (Dnmt3aR878H/+), we find that aging-induced TNFα signaling drives selective advantage of mutant HSCs concomitant with B lymphoid lineage production. Genetic loss of TNFα receptor TNFR1 impaired mutant HSC fitness while loss of TNFR2 abrogated lymphoid production and resulted in unrestrained myeloid cell production from mutant HSCs. These results support a model where clone size and lineage output can be independently targeted to harness potential beneficial aspects of clonal hematopoiesis.

ORGANISM(S): Mus musculus

PROVIDER: GSE189406 | GEO | 2021/11/25

REPOSITORIES: GEO

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Project description:Hematopoietic stem cells (HSCs) with certain somatic mutations, most commonly in the DNA methyltransferase DNMT3A, gain a clonal growth advantage leading to the development of clonal hematopoiesis (CH). The distinct functional differences that allow DNMT3A-mutant HSCs to gain a fitness advantage and outcompete wild-type HSC in the context of aging are not fully elucidated. We recently discovered that HSC aging is initiated by decline in local production of insulin-like growth factor 1 (IGF1). Here, we used a mouse model of DNMT3A-mutant CH (Dnmt3aR878H/+) to investigate the extent to which decline in IGF1 alters the selective advantage of Dnmt3aR878H/+ HSCs. Upon transplant into IGF1-deficient recipient mice, Dnmt3aR878H/+ HSCs gained enhanced selective advantage over wild-type HSCs and maintained lineage balanced blood production. As IGF1/mTOR signaling is well understood to regulate energy metabolism, we investigated underlying metabolic differences between Dnmt3aR878H/+ and wild-type HSCs. Dnmt3aR878H/+ HSPCs had similar glycolytic capacity as wild-type HSCs but enhanced mitochondrial reserve capacity and mitochondrial activation potential. To evaluate whether mitochondrial function is a targetable dependency of Dnmt3aR878H/+ HSCs, we administered the mitochondrial-targeted molecule MitoQ resulting in the depletion of their mitochondrial reserve capacity. We find that MitoQ reduces the competitive advantage of Dnmt3aR878H/+ hematopoiesis. To identify the mechanism(s) by which MitoQ alters Dnmt3aR878H/+ phenotypic expansion we evaluated transcriptional changes after MitoQ treatment and find altered response to Igf1/mTOR signaling compared to wild-type HSC. The altered response to Igf1/mTOR signaling in part mediates the Dnmt3aR878H/+ hematopoietic selective advantage. Taken together, our work supports that mitochondrial metabolic regulation is a key mechanism by which DNMT3A-mutant HSCs gain a selective advantage. Targeting this mechanism may maintain polyclonal hematopoiesis during aging and reduce the risk of CH-associated disease.

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Distinct TNF Receptors Dictate Stem Cell Fitness Versus Lineage Output in Clonal Hematopoiesis of Aging

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