bims-meprid 2024-01-21 papers

Issue of 2024‒01‒21
five papers selected by
Alessandro Carrer, Veneto Institute of Molecular Medicine

Mol Cell. 2024 Jan 10. pii: S1097-2765(23)01079-1. [Epub ahead of print]

Acetyl-CoA production by Mediator-bound 2-ketoacid dehydrogenases boosts de novo histone acetylation and is regulated by nitric oxide.

Marta Russo, Francesco Gualdrini, Veronica Vallelonga, Elena Prosperini, Roberta Noberini, Silvia Pedretti, Carolina Borriero, Pierluigi Di Chiaro, Sara Polletti, Gabriele Imperato, Mattia Marenda, Chiara Ghirardi, Fabio Bedin, Alessandro Cuomo, Simona Rodighiero, Tiziana Bonaldi, Nico Mitro, Serena Ghisletti, Gioacchino Natoli.

Histone-modifying enzymes depend on the availability of cofactors, with acetyl-coenzyme A (CoA) being required for histone acetyltransferase (HAT) activity. The discovery that mitochondrial acyl-CoA-producing enzymes translocate to the nucleus suggests that high concentrations of locally synthesized metabolites may impact acylation of histones and other nuclear substrates, thereby controlling gene expression. Here, we show that 2-ketoacid dehydrogenases are stably associated with the Mediator complex, thus providing a local supply of acetyl-CoA and increasing the generation of hyper-acetylated histone tails. Nitric oxide (NO), which is produced in large amounts in lipopolysaccharide-stimulated macrophages, inhibited the activity of Mediator-associated 2-ketoacid dehydrogenases. Elevation of NO levels and the disruption of Mediator complex integrity both affected de novo histone acetylation within a shared set of genomic regions. Our findings indicate that the local supply of acetyl-CoA generated by 2-ketoacid dehydrogenases bound to Mediator is required to maximize acetylation of histone tails at sites of elevated HAT activity.

Keywords: 2-ketoacid dehydrogenases; LPS; LPS tolerance; Mediator; acetylation; chromatin; lipopolysaccharide; macrophages; nitric oxide; pyruvate dehydrogenase

DOI: https://doi.org/10.1016/j.molcel.2023.12.033

Cell Death Discov. 2024 Jan 15. 10(1): 27

α-Ketoglutarate supplementation and NAD+ modulation enhance metabolic rewiring and radiosensitization in SLC25A1 inhibited cancer cells.

Kexu Xiang, Mikhail Kunin, Safa Larafa, Maike Busch, Nicole Dünker, Verena Jendrossek, Johann Matschke.

Metabolic rewiring is the result of the increasing demands and proliferation of cancer cells, leading to changes in the biological activities and responses to treatment of cancer cells. The mitochondrial citrate transport protein SLC25A1 is involved in metabolic reprogramming offering a strategy to induce metabolic bottlenecks relevant to radiosensitization through the accumulation of the oncometabolite D-2-hydroxyglutarate (D-2HG) upon SLC25A1 inhibition (SLC25A1i). Previous studies have revealed the comparative effects of SLC25A1i or cell-permeable D-2HG (octyl-D-2HG) treatments on DNA damage induction and repair, as well as on energy metabolism and cellular function, which are crucial for the long-term survival of irradiated cells. Here, α-ketoglutarate (αKG), the precursor of D-2HG, potentiated the effects observed upon SLC25A1i on DNA damage repair, cell function and long-term survival in vitro and in vivo, rendering NCI-H460 cancer cells more vulnerable to ionizing radiation. However, αKG treatment alone had little effect on these phenotypes. In addition, supplementation with nicotinamide (NAM), a precursor of NAD (including NAD+ and NADH), counteracted the effects of SLC25A1i or the combination of SLC25A1i with αKG, highlighting a potential importance of the NAD+/NADH balance on cellular activities relevant to the survival of irradiated cancer cells upon SLC25A1i. Furthermore, inhibition of histone lysine demethylases (KDMs), as a major factor affected upon SLC25A1i, by JIB04 treatment alone or in combination with αKG supplementation phenocopied the broad effects on mitochondrial and cellular function induced by SLC25A1i. Taken together, αKG supplementation potentiated the effects on cellular processes observed upon SLC25A1i and increased the cellular demand for NAD to rebalance the cellular state and ensure survival after irradiation. Future studies will elucidate the underlying metabolic reprogramming induced by SLC25A1i and provide novel therapeutic strategies for cancer treatment.

DOI: https://doi.org/10.1038/s41420-024-01805-x

Haematologica. 2024 Jan 18.

D-2-hydroxyglutarate supports a tolerogenic phenotype with lowered major histocompatibility class II expression in non-malignant dendritic cells and acute myeloid leukemia cells.

D-2-hydroxyglutarate (D-2-HG) accumulates in primary acute myeloid leukemia (AML) patients with mutated isocitrate dehydrogenase (IDH) and other malignancies. D-2-HG suppresses antitumor T cell immunity but little is known about potential effects on non-malignant myeloid cells. Here we show that D-2-HG impairs human but not murine dendritic cell (DC) differentiation, resulting in a tolerogenic phenotype with low major histocompatibility (MHC) class II expression. In line, IDH-mutated AML blasts exhibited lower expression of HLA-DP and were less susceptible to lysis by HLA-DP-specific T cells. Interestingly, D-2-HG reprogrammed metabolism towards increased lactate production in DCs and AML besides its expected impact on DNA demethylation. Vitamin C accelerated DNA demethylation, but only the combination of vitamin C and glycolytic inhibition lowered lactate levels and supported MHC class II expression. Our results indicate an unexpected link between the immunosuppressive metabolites 2-HG and lactic acid and suggest a potentially novel therapeutic strategy with combinations of anti-glycolytic drugs and epigenetic modulators (hypomethylating agents) or other therapeutics for the treatment of AML.

DOI: https://doi.org/10.3324/haematol.2023.283597

Cell Metab. 2024 Jan 09. pii: S1550-4131(23)00474-6. [Epub ahead of print]

Augmentation of scleral glycolysis promotes myopia through histone lactylation.

Myopia is characterized of maladaptive increases in scleral fibroblast-to-myofibroblast transdifferentiation (FMT). Scleral hypoxia is a significant factor contributing to myopia, but how hypoxia induces myopia is poorly understood. Here, we showed that myopia in mice and guinea pigs was associated with hypoxia-induced increases in key glycolytic enzymes expression and lactate levels in the sclera. Promotion of scleral glycolysis or lactate production induced FMT and myopia; conversely, suppression of glycolysis or lactate production eliminated or inhibited FMT and myopia. Mechanistically, increasing scleral glycolysis-lactate levels promoted FMT and myopia via H3K18la, and this promoted Notch1 expression. Genetic analyses identified a significant enrichment of two genes encoding glycolytic enzymes, ENO2 and TPI1. Moreover, increasing sugar intake in guinea pigs not only induced myopia but also enhanced the response to myopia induction via the scleral glycolysis-lactate-histone lactylation pathway. Collectively, we suggest that scleral glycolysis contributes to myopia by promoting FMT via lactate-induced histone lactylation.

Keywords: H3K18la; NOTCH1; glycolysis; high-sugar diet; histone lactylation; hypoxia; insulin; lactate; myofibroblast; myopia

DOI: https://doi.org/10.1016/j.cmet.2023.12.023

Nat Commun. 2024 Jan 15. 15(1): 538

Increased iron uptake by splenic hematopoietic stem cells promotes TET2-dependent erythroid regeneration.

Yu-Jung Tseng, Yuki Kageyama, Rebecca L Murdaugh, Ayumi Kitano, Jong Hwan Kim, Kevin A Hoegenauer, Jonathan Tiessen, Mackenzie H Smith, Hidetaka Uryu, Koichi Takahashi, James F Martin, Md Abul Hassan Samee, Daisuke Nakada.

Hematopoietic stem cells (HSCs) are capable of regenerating the blood system, but the instructive cues that direct HSCs to regenerate particular lineages lost to the injury remain elusive. Here, we show that iron is increasingly taken up by HSCs during anemia and induces erythroid gene expression and regeneration in a Tet2-dependent manner. Lineage tracing of HSCs reveals that HSCs respond to hemolytic anemia by increasing erythroid output. The number of HSCs in the spleen, but not bone marrow, increases upon anemia and these HSCs exhibit enhanced proliferation, erythroid differentiation, iron uptake, and TET2 protein expression. Increased iron in HSCs promotes DNA demethylation and expression of erythroid genes. Suppressing iron uptake or TET2 expression impairs erythroid genes expression and erythroid differentiation of HSCs; iron supplementation, however, augments these processes. These results establish that the physiological level of iron taken up by HSCs has an instructive role in promoting erythroid-biased differentiation of HSCs.

DOI: https://doi.org/10.1038/s41467-024-44718-0