GATA6-AS1 Regulates Intestinal Epithelial Mitochondrial Functions, and its Reduced Expression is Linked to Intestinal Inflammation and Less Favourable Disease Course in Ulcerative Colitis

Abstract Background and Aims Widespread dysregulation of long non-coding RNAs [lncRNAs] including a reduction in GATA6-AS1 was noted in inflammatory bowel disease [IBD]. We previously reported a prominent inhibition of epithelial mitochondrial functions in ulcerative colitis [UC]. However, the connection between reduction of GATA6-AS1 expression and attenuated epithelial mitochondrial functions was not defined. Methods Mucosal transcriptomics was used to conform GATA6-AS1 reduction in several treatment-naïve independent human cohorts [n=673]. RNA pull-down followed by mass spectrometry was used to determine the GATA6-AS1 interactome. Metabolomics and mitochondrial respiration following GATA6-AS1 silencing in Caco-2 cells were used to elaborate on GATA6-AS1 functions. Results GATA6-AS1 showed predominant expression in gut epithelia using single cell datasets. GATA6-AS1 levels were reduced in Crohn’s disease [CD] ileum and UC rectum in independent cohorts. Reduced GATA6-AS1 lncRNA was further linked to a more severe UC form, and to a less favourable UC course. The GATA6-AS1 interactome showed robust enrichment for mitochondrial proteins, and included TGM2, an autoantigen in coeliac disease that is induced in UC, CD and coeliac disease, in contrast to GATA6-AS1 reduction in these cohorts. GATA6-AS1 silencing resulted in induction of TGM2, and this was coupled with a reduction in mitochondrial membrane potential and mitochondrial respiration, as well as in a reduction of metabolites linked to aerobic respiration relevant to mucosal inflammation. TGM2 knockdown in GATA6-AS1-deficient cells rescued mitochondrial respiration. Conclusions GATA6-AS1 levels are reduced in UC, CD and coeliac disease, and in more severe UC forms. We highlight GATA6-AS1 as a target regulating epithelial mitochondrial functions, potentially through controlling TGM2 levels.