bims-meprid Biomed News
on Metabolic-dependent epigenetic reprogramming in differentiation and disease
Issue of 2022‒05‒15
three papers selected by
Alessandro Carrer
Veneto Institute of Molecular Medicine

  1. Mol Biol Cell. 2022 May 11. mbcE22020066
      Normal tissue and organ morphogenesis requires epithelial cell plasticity and conversion to a mesenchymal phenotype through a tightly regulated process: epithelial-to-mesenchymal transition (EMT). Alterations of EMT go far beyond cell-lineage segregation and contribute to pathologic conditions such as cancer. EMT is subject to intersecting control pathways; however, EMT's metabolic mechanism remains poorly understood. Here, we demonstrate that transforming growth factor β (TGF-β)-induced EMT is accompanied by decreased fatty acid oxidation (FAO) and reduced acetyl-coenzyme A (acetyl-CoA) levels. Acetyl-CoA is a central metabolite and the sole donor of acetyl groups to acetylate key proteins. Further, the short-chain fatty acid acetate increases acetyl-CoA levels-robustly inhibiting EMT and cancer cell migration. Acetate can restore EMT-associated α-tubulin acetylation levels, increasing microtubule stability. Transcriptome profiling and flow cytometric analysis show that acetate inhibits the global gene expression program associated with EMT and the EMT-associated G1 cell cycle arrest. Taken together, these results demonstrate that acetate is a potent metabolic regulator of EMT and that therapeutic manipulation of acetate metabolism could provide the basis for treating a wide range of EMT-linked pathological conditions, including cancer.
  2. FASEB J. 2022 May;36 Suppl 1
      CoA metabolites play a critical role in the epigenetic regulation of gene expression. Of particular significance is acetyl-CoA, a primary metabolite used by histone acetyltransferases to modify histone tails and therefore control chromatin state. In cancer cells, the dysregulation of acetyl-CoA can lead to the aberrant expression of genes controlling cell growth. One challenge in studying these acetyl-CoA dependent functions is the lack of optical methods to detect CoA metabolites. Towards that goal, we report a bioluminescence energy transfer (BRET)-based approach to detect acetyl-CoA. Our strategy is inspired by recent biophysical and chemoproteomic analyses of human acetyltransferases, which revealed that members of the N-terminal (NAA) acetyltransferase family preferentially bind acetyl-CoA over CoA. To explore whether we could develop an acetyl-CoA selective ligand-displacement assay, we first recombinantly expressed and purified a NAA-Nanoluc fusion protein. Next, we demonstrated its ability to generate a BRET signal when incubated with CoA-fluorophore conjugates. Finally, we evaluated whether NAA-Nanoluc BRET was altered by the addition of CoA metabolites, which revealed a direct relationship between the affinity of the CoA and optical signal. We report the first tunable indicator displacement assay for CoA metabolites and provide a new approach for studying the engagement of acetyltransferase enzymes by small molecule inhibitors.
  3. FASEB J. 2022 May;36 Suppl 1
      Onset of brain metastases (BMs) in breast cancer patients is considered an end-stage event, with no effective drug treatment and a median survival after diagnosis measured in months. Thus, there is an urgent need to develop novel treatment strategies. Metastatic breast cancer cells colonizing the brain encounter adverse 'nutritional environment', as the levels of key metabolic fuels such as glucose are much lower, in part because they are avidly consumed by neurons. To overcome this challenge, brain-metastatic cancer cells rely on acetate as a fuel source and convert it into acetyl-CoA via upregulation of acetyl-CoA synthetase 2 (ACSS2) enzyme. We have previously shown that brain tumors increase the nutrient sensing post-translational modification O-GlcNAcylation and O-GlcNAc transferase (OGT) levels to regulate acetate metabolism into acetyl-CoA via increased phosphorylation of ACSS2 on Ser-267 in a cyclin dependent kinase 5 (CDK5)-dependent manner, increasing brain tumor growth. Here, we show that human breast cancer cells selected to metastasize to the brain contain increased levels of O-GlcNAc, OGT and ACSS2-Ser267 phosphorylation compared to parental cells and show that human breast cancer brain metastatic patient samples contain elevated ACSS2-Ser-267 levels. Moreover, overexpression of OGT or ACSS2-S267D phospho-mimetic mutant confer a growth advantage on brain metastatic breast cancer cells in an in vivo intracranial xenograft model, may be due to an increase in lipogenic proteins. Additionally, we show that pharmacologically targeting CDK5 and ACSS2 with small molecule inhibitors reduces tumor growth in a novel orthotopic ex vivo brain slice model. These results suggest a crucial role for OGT/CDK5/ACSS2 signaling in transducing nutritional state to regulate acetate metabolism in breast cancer BM cells and identify CDK5 and ACSS2 as novel therapeutic targets for treatment of breast cancer brain metastasis.