Determining the Mechanism by which PRDM16 Maintains the Adult Small Intestinal Epithelium

Abstract

The intestinal epithelium is a well‐organized tissue that undergoes continuous cell turnover, with most cells being replaced every 4–5 days. PRDM16 is a large zinc‐finger containing transcription factor that, in addition to its well‐studied role in brown/beige adipose, regulates maintenance of neuronal and hematopoietic stem cells. However, the role of PRDM16 in other tissues is not well understood. We find that acute global deletion of Prdm16 in adult mice causes death within ten days. The Prdm16‐deleted mice begin to lose weight and appear weak and lethargic, with visibly distended and pale intestines. Histological analysis shows that PRDM16 is selectively and highly expressed in the intestinal epithelium of the duodenum and jejunum. Apoptotic cells are prevalent in the crypt, particularly in the transit amplifying zone by 3 days after Prdm16 deletion. By 5 days after deletion, intestinal tissue appears disorganized, with an abnormal accumulation of secretory cells in the crypt that express markers of both the goblet and Paneth cell lineages, indicating defects in differentiation. Interestingly, we could detect no obvious defects in Notch signaling. We performed RNA‐seq on isolated crypts to identify candidate signaling pathways that change in the intestine shortly after global knockout of Prdm16. A striking upregulation of P53‐activated apoptotic genes occurs immediately following the disappearance of PRDM16 protein, as well as an induction of Type‐I Interferon signaling. Independent of this, we see marked downregulation of genes involved in metabolic pathways. Studying the effects of PRDM16 ex vivo, we find that enteroid culture recapitulates the phenotypes observed in vivo, with Prdm16 deletion causing induction of apoptosis and a failure of intestinal enteroids to form buds. Further, we show that shRNA mediated knockdown of Prdm16 is sufficient to block the formation of enteroids. Our phenotype is ameliorated but not fully rescued by additional deletion of p53 both in vivo and ex vivo. We are currently focusing on defects in mitochondrial function, which appear to be a second major driver of our intestinal phenotype.Support or Funding InformationNRSA NIDDK F32 DK105743‐03 Pilot Grant NIDDK P30‐DK050306This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.