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Hematologic DNMT3A Reduction and High Fat Diet Synergize to Promote Weight Gain and Tissue Inflammation

ABSTRACT: In the aging hematopoietic system, blood cell production becomes dominated by a limited number of hematopoietic stem cell (HSC) clones. While somatic mutations in the de novo DNA methyltransferase 3A (DNMT3A) frequently drive clone dominance, the aging milieu also likely contributes to selection of variant HSCs. The detrimental impact of clonal hematopoiesis on organismal health is thought to be mediated by differentiated progeny of variant HSCs through mechanisms as yet poorly understood. Here, we examined the interaction between high fat diet (HFD) as an inflammatory stressor and a hematopoietic system haploinsufficient for DNMT3A. Strikingly, HFD accelerated weight gain in mice harboring bone marrow with reduced DNMT3A. Moreover, distal tissues of such mice including pancreas, adipose, and spleen, harbored high levels of mutant macrophages that impacted tissue function. Aberrant DNA methylation and pro-inflammatory transcriptional activation in mutant-derived myeloid cells correlated with increased IL-6 and TNFa signaling. Together, these findings identify synergism between HFD and DNMT3A haploinsufficiency that, through increased inflammatory myeloid cell functions, can contribute to deterioration in organismal health.

ORGANISM(S): Mus musculus

PROVIDER: GSE208075 | GEO | 2024/01/01

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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Hematologic DNMT3A Reduction and High Fat Diet Synergize to Promote Weight Gain and Tissue Inflammation

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