(PO07-31-22) Milk-Derived miR-22-3p Promotes Proliferation of Human Intestinal Epithelial Cells (HIECs) by Regulating Gene Expression

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Presenting Author(s)

RJ

Rulan Jiang, PhD
– Project Scientist, UC Davis, Davis, California, United States

Co-Author(s)

BL

Bo Lonnerdal, PhD
– Distinguished Professor Emeritus of Nutrition & Internal Medicine, University of California Davis, Davis, California, United States

Disclosure(s):

Rulan Jiang, PhD: No relevant financial relationship(s) with ineligible companies to disclose.

Objectives: MicroRNAs (miRNAs) are small non-coding RNA involved in RNA silencing and post-transcriptional regulation of gene expression. Milk exosomes are microvesicles containing miRNAs, and miR-22-3p (miR-22) abundantly appears in human milk exosomes. Both human milk exosomes and miR-22 survive in vitro gastrointestinal digestion. The aim of the current study was to evaluate effects of milk derived miR-22 on intestinal epithelial cells in early life.

Methods: To evaluate effects of miR-22 on intestinal epithelial cells and mimic uptake of miR-22 in exosomes by intestinal epithelial cells, miR-22 was transfected to human intestinal epithelial cells (HIECs) using Lipofectamine, and then total RNA was isolated after 24 h for microarray assay. After microarray results were verified by qRT-PCR, microarray they were analyzed using the Bioconductor package limma and compared with miR-22 predicted target genes to identify a direct target gene for miR-22 in HIECs.

Results: Totally, 608 genes were markedly regulated by miR-22. Based on Gene Ontology terms, the roles of miR-22 in HIECs include promotion of proliferation and regulation of immune functions. A proliferation assay (BrdU) was subsequently conducted to confirm the effect of miR-22 on promotion of proliferation of HIECs. Based on analysis of the microarray results and miR-22 predicted target genes, C/EBPδ, a transcription factor, may be a direct target for miR-22. In miR-22 transfected HIECs, transcription and translation of the C/EBPδ gene was significantly inhibited, and cell proliferation was increased when the C/EBPδ gene was silenced by siRNA. A luciferase assay showed that miR-22 specifically bound to the 3'-untranslated region of the C/EBPδ gene.

Conclusions: Milk-derived miR-22 promotes intestinal proliferation by modifying gene expression, and C/EBPδ may be an important direct target for miR-22 in human intestinal epithelial cells.

Funding Sources: Intramural funds