Co-regulatory Proteins Integrate Metabolic Signals to Regulate ESRRG Transcriptional Transactivation in Stomach Parietal Cell Differentiation

Abstract

Acid-producing stomach parietal cells (PC) are metabolically active and energy demanding cells. Aberrant PC function and census leads to complications ranging from peptic ulcers to stomach adenocarcinoma. Effcient energy expenditure and catabolic metabolism are required for normal PC differentiation from progenitor cells. Here, our data show that the master metabolic transcriptional factor, estrogen-related receptor gamma ( ESRRG), governs murine and human PC differentiation. We are further investigating how known metabolically controlled co-regulatory proteins — Sirtuin 1 (SIRT1), Nuclear Receptor Subfamily 0 Group B Member 2 (NR0B2), and CREB/ATF BZIP Transcription Factor (CREBZF, or SMILE) — integrate stimuli to enable ESRRG transcriptional activation during PC emergence from precursors. Specifically, our lab has developed an acute and reversible PC ablation model to monitor PC recovery in which Simian diphtheria toxin receptor (DTR) expression under the Atp4b promoter targets PC-specific ablation by diphtheria toxin (DT). Additionally, we employ high-dose tamoxifen (HD TAM), which causes a more general gastric injury (independent of tamoxifen effects on estrogen) from PC death along with reactive spasmolytic polypeptide expressing metaplasia (SPEM) of remaining cells. Immunofluorescence, western blotting, and qRT-PCR revealed SIRT1 is upregulated before emergence of early PC clones post-DT and decreases later, suggesting positive regulation of early PC lineage-commitment from stem cells. During the same early time frame, factors NR0B2 and CREBZF decreased, suggesting contrasting roles. Administration of Resv to mice accelerated PC recovery after injury and expanded PCs even at homeostasis. ChIP and ongoing ChIP-seq and Cut&Run assays show ESRRG binds cis-regulatory elements of the metabolic genes and the co-regulatory proteins to promote PC lineage commitment in both mice and in a human gastric cell line in which stable ESRRG-GFP is expressed under a doxycycline-inducible promoter. In other ongoing work, we are generating mice with PC-specific Sirt1/ Nr0b2 ablation to further dissect PC regeneration dynamics and conducting gastric organoid experiments with NR0B2/SIRT1 pharmacological modulators to monitor PC differentiation effects. These organoid samples will be further subjected to epigenetic analysis (Cut&Run, ATACseq) to study chromatin landscape changes. We conclude that cellular metabolic integration by co-regulators enables ESRRG-mediated transactivation during PC differentiation, and SIRT1 promotes early PC lineage-commitment that might offer a promising pro-PC differentiation therapeutic strategy. This work is supported by funding from the NIH through the National Institute of Diabetes and Digestive and Kidney Diseases and the National Cancer Institute. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.