Abstract PR07: Connecting acetate and citrate metabolism with epigenetic regulation of hematopoiesis

Abstract

Here we hypothesize that acetate metabolism and citrate metabolism play integral roles to balance the fate decision of HSCs and that targeting Acly-Coa Synthetase Short-Chain 2 (ACSS2) and ATP-Citrate Lyase (ACLY) will impact epigenetic modifications and gene expression to affect cell fate.

Hematopoietic stem cells (HSCs) undergo self-renewal or differentiation to generate a variety of myeloid, erythroid, and lymphoid cells through hematopoiesis. Hematopoiesis precisely balances many stimuli to maintain HSC self-renewal and differentiation. These stimuli classically consist of chemokines, cytokines, and transcription factors acting at key precursor stages to influence cell fate. Metabolic molecules can directly influence epigenetic state, chromatin accessibility, and cell lineage maturation via regulation of epigenetic modifying enzymes. However, understanding remains limited of how HSCs balance metabolic and other microenvironmental stimuli to regulate self-renewal and differentiation.

Acetate and citrate metabolism regulate methylation and acetylation, respectively, and we investigated how these pathways may impact hematopoiesis. The Rathmell lab has previously shown that metabolism is a key regulator of T effector cells, as we discovered that Glutaminase deficiency promotes Th1 effector differentiation. We have now shown that ACLY inhibition can drive myeloid differentiation. To test our hypothesis, we treated methylcellulose-cultured HSCs with small-molecule inhibitors of ACLY and ACSS2 for two weeks to determine if inhibition of these enzymes alters lineage commitment of HSCs to myeloid vs. erythroid fate decisions. We observed that inhibition of ACLY using SB-204990 drives HSC differentiation into myeloid fates, indicated by increased CD11b expression. Further, treatment with SB-204990 decreased population of the conventional stem compartment Sca-1+ c-Kit+ Lin-. We will now use conditionally-deficient models of ACLY to directly and genetically establish the roles of acetate and citrate metabolism in HSC self-renewal and differentiation. Single-cell RNA-sequencing and chromatin accessibility assays will be employed to identify metabolically sensitive gene regulatory networks within heterogeneous hematopoietic cell populations. Unraveling the link between acetate metabolism, citrate metabolism, and stem cell function presents an opportunity to develop a more nuanced picture of metabolism’s increasingly discussed role as a regulator of cellular development. Ultimately, elucidating possible mechanisms to promote hematopoietic lineage differentiation presents a novel therapeutic opportunity for various hematologic malignancies and disorders.

Citation Format: Dalton L. Greenwood, Jeffrey C. Rathmell. Connecting acetate and citrate metabolism with epigenetic regulation of hematopoiesis [abstract]. In: Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020; 2020 Oct 15-16. Philadelphia (PA): AACR; Cancer Res 2020;80(23 Suppl):Abstract nr PR07.