Probes for LONG

Abstract

BACKGROUND & AIMS:

Inflammation affects regeneration of the intestinal epithelia; long noncoding RNAs (lncRNAs) regulate cell functions, such as proliferation, differentiation, and migration. We investigated the mechanisms by which the lncRNA H19, imprinted maternally expressed transcript (H19) regulates regeneration of intestinal epithelium using cell cultures and mouse models of inflammation.

METHODS:

We performed RNA-sequencing transcriptome analyses of intestinal tissues from mice with lipopolysaccharide (LPS)-induced sepsis to identify lncRNAs associated with inflammation; findings were confirmed by quantitative real-time polymerase chain reaction and in situ hybridization analyses of intestinal tissues from mice with sepsis or dextran sulfate sodium (DSS)-induced mucosal wound healing and patients with ulcerative colitis compared to healthy individuals (controls). We screened cytokines for their ability to induce expression of H19 in HT-29 cells and intestinal epithelial cells (IECs), and confirmed findings in crypt epithelial organoids derived from mouse small intestine. IECs were incubated with different signal transduction inhibitors and effects on H19 lncRNA levels were measured. We assessed intestinal epithelial proliferation or regeneration in H19ΔEx1/+ mice given LPS or DSS vs wild-type littermates (control mice). H19 was overexpressed in IECs using lentiviral vectors and cell proliferation was measured. We performed RNA antisense purification, RNA immunoprecipitation, and luciferase reporter assays to study functions of H19 in IECs.

RESULTS:

In RNA-sequencing transcriptome analysis of lncRNA expression in intestinal tissues from mice, we found that levels of H19 lncRNA changed significantly with LPS exposure. Levels of H19 lncRNA increased in intestinal tissues of patients with ulcerative colitis, micewith LPS-induced and polymicrobial sepsis, or mice with DSS-induced colitis, compared with controls. Increased H19 lncRNA localized to epithelial cells in the intestine, regardless of Lgr5 messenger RNA expression. Exposure of IECs to interleukin 22 (IL22) increased levels of H19 lncRNA with time and dose, which required STAT3 and protein kinase A activity. IL22 induced expression of H19 in mouse intestinal epithelial organoids within 6 hours. Exposure to IL22 increased growth of intestinal epithelial organoids derived from control mice, but not H19ΔEx1/+ mice. Overexpression of H19 in HT-29 cells increased their proliferation. Intestinal mucosa healed more slowly after withdrawal of DSS from H19ΔEx1/+ mice vs control mice. Crypt epithelial cells from H19ΔEx1/+ mice proliferated more slowly than those from control miceafter exposure to LPS. H19 lncRNA bound to p53 and microRNAs that inhibit cell proliferation, including microRNA 34a and let-7; H19 lncRNA binding blocked their function, leading to increased expression of genes that promote regeneration of the epithelium.

CONCLUSIONS:

The level of lncRNA H19 is increased in inflamed intestinal tissues from mice and patients. The inflammatory cytokine IL22 induces expression of H19 in IECs, which is required for intestinal epithelial proliferation and mucosal healing. H19 lncRNA appears to inhibit p53 protein and microRNA 34a and let-7 to promote proliferation of IECs and epithelial regeneration.

Abstract

Long noncoding RNA (lncRNA) H19 is abundantly expressed in fetal liver. Its expression is significantly diminished in adult healthy liver but is re‐induced in chronic liver diseases, including cholestasis. In this study, we developed a new method with combined in situhybridization (ISH) and immunofluorescence (IF) colabeling to establish an H19 expression profile with both parenchymal and nonparenchymal cell‐specific markers in the livers of cholestatic mouse models and patients with cholestasis. H19RNA+ cells showed no colocalization with biliary epithelial cell marker cytokeratin 19 (CK19)+cholangiocytes but were immediately adjacent to biliary structures in bile duct ligation (BDL), 3,5‐diethoxycarbony1‐1,4‐dihydrocollidine (DDC), and multidrug‐resistant gene 2 knockout (Mdr2–/–) mouse models and in human primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) liver specimens. In contrast, double‐positive H19RNA+/sex‐determining region Y (SRY)‐box 9 (SOX9)+ ductal progenitor cells, H19RNA+/hepatocyte nuclear factor 4α (HNF4α)+ hepatocytes, H19RNA+/F4/80+ Kupffer cells, HNF4α+/SOX9+ hybrid hepatocytes, as well as triple‐positive H19RNA+/HNF4α+/SOX9+ periportal hepatocytes were identified. In addition, H19RNA could not be detected in mesenchymal cell marker desmin+ cells. Furthermore, H19RNA was predominately detected in cytoplasm with a small amount at the interspace with neighboring cells. Conclusion: H19RNA is localized in HNF4α+ periportal hepatocytes, SOX9+ ductal progenitor cells, and F4/80+ Kupffer cells but not in CK19+ cholangiocytes and desmin+ stellate cells in cholestatic livers.