Hypoxic environment promotes barrier formation in human intestinal epithelial cells through regulation of miRNA-320a expression

Abstract

38Intestinal epithelial cells (IECs) are exposed to the low-oxygen environment present in the 39 lumen of the gut. These hypoxic conditions are on one hand fundamental for the survival of 40 the commensal microbiota, and on the other hand, favor the formation of a selective 41 semipermeable barrier allowing IECs to transport essential nutrients/water while keeping the 42 sterile internal compartments separated from the lumen containing commensals. The 43 hypoxia-inducible factor (HIF) complex, which allows cells to respond and adapt to fluctuations 44 in oxygen levels, has been described as a key regulator in maintaining IEC barrier function by 45 regulating their tight junction integrity. In this study, we sought to better evaluate the 46 mechanisms by which low oxygen conditions impact the barrier function of human IECs. By 47 profiling miRNA expression in IECs under hypoxia, we identified miRNA-320a as a novel barrier 48 formation regulator. Using pharmacological inhibitors and short hairpin RNA-mediated 49 silencing we could demonstrate that expression of this miRNA was HIF-dependent. 50 Importantly, using over-expression and knock-down approaches of miRNA-320a we could 51 confirm its direct role in the regulation of barrier functions in human IECs. These results reveal 52 an important link between miRNA expression and barrier integrity, providing a novel insight 53 into mechanisms of hypoxia-driven epithelial homeostasis. 54

High performance inkjet printed embedded electrochemical sensors for monitoring hypoxia in a gut bilayer microfluidic chip

“…Quick barrier formation could be observed in intestinal epithelial cells – T84 under hypoxic conditions, which was well explained through profiling miRNA-320a expression and TEER assessment by Muenchau et al 29 Most of these studies suggest direct dependency of barrier regulation, through the expression of multiples genes, on hypoxia-induced transcription factor hypoxia inducible factor (HIF). 28,30–33 Specifically, in the milieu of epithelial barrier function, the intestinal trefoil factors (TFFs) are responsible for intestinal cell-specific barrier-protective features which are explicitly upregulated and HIF-1α dependent under hypoxia.…”

Physiological hypoxia improves growth and functional differentiation of human intestinal epithelial organoids

“…HIF-1 is crucial for cell survival, metabolism, and other functions in low oxygen environments, including maintaining epithelial barrier integrity and antimicrobial functions (27). Stabilization of HIF-1a upregulates the expression of, e.g., thigh junction proteins (28), mucus-related genes (29), and anti-microbial proteins like defensins (30).…”