Loss of Cpt1a results in elevated glucose-fueled mitochondrial oxidative phosphorylation and defective hematopoietic stem cells
Jue Li, Jie Bai, Vincent T. Pham, Michihiro Hashimoto, Maiko Sezaki, Qili Shi, Qiushi Jin, Chenhui He, Amy Armstrong, Tian Li, Mingzhe Pan, Shujun Liu, Yu Luan, Hui Zeng, Paul R. Andreassen, Gang Huang
Jue Li, Jie Bai, Vincent T. Pham, Michihiro Hashimoto, Maiko Sezaki, Qili Shi, Qiushi Jin, Chenhui He, Amy Armstrong, Tian Li, Mingzhe Pan, Shujun Liu, Yu Luan, Hui Zeng, Paul R. Andreassen, Gang Huang
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Research Article Hematology Metabolism

Loss of Cpt1a results in elevated glucose-fueled mitochondrial oxidative phosphorylation and defective hematopoietic stem cells

Abstract

Hematopoietic stem cells (HSCs) rely on self-renewal to sustain stem cell potential and undergo differentiation to generate mature blood cells. Mitochondrial fatty acid β-oxidation (FAO) is essential for HSC maintenance. However, the role of carnitine palmitoyl transferase 1a (CPT1A), a key enzyme in FAO, remains unclear in HSCs. Using a Cpt1a hematopoiesis-specific conditional-KO (Cpt1aΔ/Δ) mouse model, we found that loss of Cpt1a led to HSC defects, including loss of HSC quiescence and self-renewal and increased differentiation. Mechanistically, we found that loss of Cpt1a resulted in elevated levels of mitochondrial respiratory chain complex components and their activity, as well as increased ATP production and accumulation of mitochondrial ROS in HSCs. Taken together, this suggests hyperactivation of mitochondria and metabolic rewiring via upregulated glucose-fueled oxidative phosphorylation (OXPHOS). In summary, our findings demonstrate an essential role for Cpt1a in HSC maintenance and provide insight into the regulation of mitochondrial metabolism via control of the balance between FAO and glucose-fueled OXPHOS.

Authors

Jue Li, Jie Bai, Vincent T. Pham, Michihiro Hashimoto, Maiko Sezaki, Qili Shi, Qiushi Jin, Chenhui He, Amy Armstrong, Tian Li, Mingzhe Pan, Shujun Liu, Yu Luan, Hui Zeng, Paul R. Andreassen, Gang Huang

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Figure 7

Increased levels and activity of mitochondrial respiratory complex components in Cpt1aΔ/Δ HSCs.

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Increased levels and activity of mitochondrial respiratory complex compo...
(A) Left: BN-PAGE immunoblots of mitochondrial complexes and supercomplexes contents in mitochondria of c-Kit+ cells. The supercomplexes were visualized by antibodies against subunits of complex I (NDUFA9), complex II (SDHA), complex III (UQCRC2), complex IV (COX4a), and complex V (ATP5A1). Representative data from 3 independent experiments are shown. Right: SDS-PAGE immunoblots of the mitochondrial internal controls mitochondrial ACO2 and CS in c-Kit+ cells. Representative data from 3 independent experiments are shown. (B) Relative expression of complexes I–V, CS, and ACO2 in c-Kit+ cells. n = 3 per group. (C) Relative activity of complexes I, II, III, and IV was measured by ELISA in c-Kit+ cells. n = 4 or 5. (D) Relative ATP levels detected by ELISA of LT-HSCs. n = 4 or 5. (E) Relative MFI levels of mtROS measured by MitoSOX in LT-HSCs. n = 7 or 6. (F) Relative MFI levels of γH2A.X in LT-HSCs. n = 5 per group. (G) Diagrammatic summary of metabolic reprogramming in HSCs (created with BioRender.com). Data represent the mean ± SEM. *P < 0.05 and **P < 0.01, by Student’s t test.