: Postprint online verfügbar 11/2022 möglich sobald bei der ZB eingereicht worden ist.
Epithelial XBP1 coordinates TP53-driven DNA damage responses and suppression of intestinal carcinogenesis.
Gastroenterology, DOI: 10.1053/j.gastro.2021.09.057 (2021)
DOI Verlagsversion bestellen
BACKGROUND AIMS: Throughout life, the intestinal epithelium undergoes constant self-renewal from intestinal stem cells. Together with genotoxic stressors and failing DNA repair, this self-renewal causes susceptibility towards malignant transformation. X-box binding protein 1 (XBP1) is a stress sensor involved in the unfolded protein response (UPR). We hypothesized that XBP1 acts as a signaling hub to regulate epithelial DNA damage responses. METHODS: Data from the TCGA were analyzed for association of XBP1 with CRC survival and molecular interactions between XBP1 andp53 pathway activity. The role of XBP1 in orchestrating p53-driven DNA damage response was tested in-vitro, in mouse models of chronic intestinal epithelial DNA damage (Xbp1/H2bfl/fl, Xbp1ΔIEC, H2bΔIEC, H2b/Xbp1ΔIEC) and via orthotopic tumor organoid transplantation. Transcriptome analysis of intestinal organoids was performed to identify molecular targets of Xbp1-mediated DNA damage response. RESULTS: In the TCGA dataset of CRC, low XBP1 expression was significantly associated with poor overall survival (OS) and reduced p53 pathway activity. In-vivo, H2b/Xbp1ΔIEC mice developed spontaneous intestinal carcinomas. Orthotopic tumor organoid transplantation revealed a metastatic potential of H2b/Xbp1ΔIEC-derived tumors. RNA sequencing of intestinal organoids (H2b/Xbp1fl/fl, H2bΔIEC, H2b/Xbp1ΔIEC, H2b/p53ΔIEC) identified a transcriptional program downstream of p53, in which XBP1 directs DNA damage-induced Ddit4l expression. DDIT4L inhibits mTOR-mediated phosphorylation of 4E-BP1. Pharmacological mTOR inhibition suppressed epithelial hyperproliferation via 4E-BP1. CONCLUSIONS: Our data suggest a crucial role for XBP1 in coordinating epithelial DNA damage responses and stem cell function via a p53-DDIT4L-dependent feedback mechanism.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Crc ; Dna Damage ; Xbp1 ; Intestinal Epithelial Cell ; P53
ISSN (print) / ISBN 0016-5085
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Computational Biology (ICB)