bims-meprid 2022-09-11 papers

Issue of 2022‒09‒11
three papers selected by
Alessandro Carrer
Veneto Institute of Molecular Medicine

Obesity (Silver Spring). 2022 Sep 05.

High-fat diet decreases H3K27ac in mice adipose-derived stromal cells.

Viviane S da Silva, Jussara J Simão, Victor Plata, Andressa França de Sousa, Roberta D C da Cunha de Sá, Cleiton Fagundes Machado, Taiza Stumpp, Maria Isabel C Alonso-Vale, Lucia Armelin-Correa.

OBJECTIVE: The study goal was to analyze the effects of a high-fat diet (HFD) on the histone 3 lysine 27 (H3K27) posttranscriptional modifications and the expression of histone-modifying enzymes in adipose-derived stromal cells (ASCs) from white adipose tissue (WAT).METHODS: Male C57BL/6J mice received control or HFD for 12 weeks. The ASCs were isolated from subcutaneous and visceral (epididymal) WAT, cultivated, and evaluated for expression of H3K27 trimethylation (H3K27me3) and H3K27 acetylation (H3K27ac) by Western blot. The transcription of histone-modifying enzymes was analyzed by real-time polymerase chain reaction.
RESULTS: When compared with control, HFD ASCs showed a decrease in H3K27ac enrichment in subcutaneous and visceral WAT and ATP-citrate lyase expression in subcutaneous WAT. Curiously, the expression of CREB-binding protein was increased in visceral ASCs from HFD-fed mice.
CONCLUSIONS: These results show that an HFD significantly reduces acetylation of H3K27 in ASCs and the expression of ATP-citrate lyase in subcutaneous ASCs, suggesting that, in this fat depot, the H3K27ac reduction could be partly due to lower acetyl-coenzyme A availability. H3K27ac is an epigenetic mark responsible for increasing the transcription rate and its reduction can have an important impact on ASC proliferation and differentiation potential.

DOI: https://doi.org/10.1002/oby.23537

Cell Metab. 2022 Sep 06. pii: S1550-4131(22)00351-5. [Epub ahead of print]34(9): 1280-1297.e9

Methionine metabolism controls the B cell EBV epigenome and viral latency.

Rui Guo, Jin Hua Liang, Yuchen Zhang, Michael Lutchenkov, Zhixuan Li, Yin Wang, Vicenta Trujillo-Alonso, Rishi Puri, Lisa Giulino-Roth, Benjamin E Gewurz.

Epstein-Barr virus (EBV) subverts host epigenetic pathways to switch between viral latency programs, colonize the B cell compartment, and reactivate. Within memory B cells, the reservoir for lifelong infection, EBV genomic DNA and histone methylation marks restrict gene expression. But this epigenetic strategy also enables EBV-infected tumors, including Burkitt lymphomas, to evade immune detection. Little is known about host cell metabolic pathways that support EBV epigenome landscapes. We therefore used amino acid restriction, metabolomic, and CRISPR approaches to identify that an abundant methionine supply and interconnecting methionine and folate cycles maintain Burkitt EBV gene silencing. Methionine restriction, or methionine cycle perturbation, hypomethylated EBV genomes and de-repressed latent membrane protein and lytic gene expression. Methionine metabolism also shaped EBV latency gene regulation required for B cell immortalization. Dietary methionine restriction altered murine Burkitt xenograft metabolomes and de-repressed EBV immunogens in vivo. These results highlight epigenetic/immunometabolism crosstalk supporting the EBV B cell life cycle and suggest therapeutic approaches.

Keywords: dietary amino acid restriction; folate metabolism; gamma-herpesvirus; immunometabolism; lytic reactivation; methionine cycle; methionine metabolism; one-carbon metabolism; tumor virus; viral latency

DOI: https://doi.org/10.1016/j.cmet.2022.08.008

Elife. 2022 Sep 07. pii: e73754. [Epub ahead of print]11

Epigenetic remodeling by vitamin C potentiates plasma cell differentiation.

Heng-Yi Chen, Ana Almonte-Loya, Fang-Yun Lay, Michael Hsu, Eric Johnson, Edahí González-Avalos, Jieyun Yin, Richard S Bruno, Qin Ma, Hazem E Ghoneim, Daniel J Wozniak, Fiona E Harrison, Chan-Wang Jerry Lio.

Ascorbate (vitamin C) is an essential micronutrient in humans. The severe chronic deficiency of ascorbate, termed scurvy, has long been associated with increased susceptibility to infections. How ascorbate affects the immune system at the cellular and molecular levels remained unclear. From a micronutrient analysis, we identified ascorbate as a potent enhancer for antibody response by facilitating the IL-21/STAT3-dependent plasma cell differentiation in mouse and human B cells. The effect of ascorbate is unique as other antioxidants failed to promote plasma cell differentiation. Ascorbate is especially critical during early B cell activation by poising the cells to plasma cell lineage without affecting the proximal IL-21/STAT3 signaling and the overall transcriptome. As a cofactor for epigenetic enzymes, ascorbate facilitates TET2/3-mediated DNA modification and demethylation of multiple elements at the Prdm1 locus. DNA demethylation augments STAT3 association at the Prdm1 promoter and a downstream enhancer, thus ensuring efficient gene expression and plasma cell differentiation. The results suggest that an adequate level of ascorbate is required for antibody response and highlight how micronutrients may regulate the activity of epigenetic enzymes to regulate gene expression. Our findings imply that epigenetic enzymes can function as sensors to gauge the availability of metabolites and influence cell fate decisions.

Keywords: B cells; TET; epigenetics; human; immunology; inflammation; micronutrients; mouse; plasma cells; vitamin C

DOI: https://doi.org/10.7554/eLife.73754