DDX5 promotes oncogene C3 and FABP1 expressions and drives intestinal inflammation and tumorigenesis

Abstract

Tumorigenesis in different segments of the intestinal tract involves tissue-specific oncogenic drivers. In the colon, complement component 3 (C3) activation is a major contributor to inflammation and malignancies. By contrast, tumorigenesis in the small intestine involves fatty acid–binding protein 1 (FABP1). However, little is known of the upstream mechanisms driving their expressions in different segments of the intestinal tract. Here, we report that the RNA-binding protein DDX5 binds to the mRNA transcripts of C3 and Fabp1 to augment their expressions posttranscriptionally. Knocking out DDX5 in epithelial cells protected mice from intestinal tumorigenesis and dextran sodium sulfate (DSS)–induced colitis. Identification of DDX5 as a common upstream regulator of tissue-specific oncogenic molecules provides an excellent therapeutic target for intestinal diseases.

RNA binding protein DDX5 directs tuft cell specification and function to regulate microbial repertoire and disease susceptibility in the intestine

“…To isolate IECs, intestinal tissues were first incubated in 5 mM EDTA (Invitrogen) in HBSS (Gibco) containing 1 mM DTT (Invitrogen) for 20 min at 37°C with 200 rpm agitation, and then incubated in a second wash of 5 mM EDTA in HBSS without DTT for another 20 min at 37°C with agitation. Single-cell suspensions released into the EDTA solutions were pooled and confirmed to contain over 85% EpCAM + IECs as reported previously 38. For the lamina propria, IEC-depleted tissues from post-EDTA washes were digested in a HBSS solution containing 10% foetal bovine serum (FBS) (Peak Serum), 1.0 mg/mL Collagenase D (Roche), 100 µg/mL DNase I (Sigma-Aldrich), and 50 U/mL dispase (Worthington Biochemical) at 37°C for 30–45 min.…”

“…IEC transcriptomes from WT IEC and DDX5 △IEC littermates were previously reported 38. Gene set enrichment analysis (GSEA) was carried out using the preranked mode of the GSEA software with default settings 51.…”

“…They can also partner with transcription factors to regulate gene expression 34–37. Our previous study revealed that DDX5 is the highest expressed member of the DDX family in the intestine epithelium 38. Overexpression of DDX5 predicts worse relapse-free survival in colorectal cancer (CRC) patients,39–41 and knockdown of DDX5 can significantly inhibited the growth of cancer cells in xenograft models 42 43.…”

“…Overexpression of DDX5 predicts worse relapse-free survival in colorectal cancer (CRC) patients,39–41 and knockdown of DDX5 can significantly inhibited the growth of cancer cells in xenograft models 42 43. We have recently reported that knocking out DDX5 in IECs protected against dextran sulfate sodium induced colitis as well as tumour formation in mice on a susceptible background 38. Given the emerging role of intestinal tuft cells in regulating intestinal inflammation and tumourigenesis, we asked whether changes in tuft cell specification and/or function may underly the contribution of DDX5 to intestinal inflammation and tumourigenesis.…”

RORγt serine 182 tightly regulates T cell heterogeneity to maintain mucosal homeostasis and restrict tissue inflammation

“…Cells were kept for RNA isolation or flow cytometry. The H&E slides from each sample were scored in a double-blind fashion as described previously (Abbasi et al, 2020). For T cell transfer model of colitis, 0.5 million naive CD4 + T cells isolated from mouse splenocytes using the Naive CD4 + T Cell Isolation Kit (Miltenyi), as described above, were injected intraperitoneally into Rag1 -/recipients.…”