Studies On Identification And Regulation Of Cross-kingdom Plant MicroRNAs

microRNAs(miRNAs)are a class of small non-coding RNAs that mainly regulate gene expression at the post-transcriptional level.Increasing evidence shows that extracellular plant miRNAs can survive the harsh conditions of the human digestive system and are transmited to human cells,where they specifically target human genes and affect the corresponding physiological functions.However,some scholars have raised objections that such plant miRNAs may come from cross-contamination during sample preparation and sequencing,as well as systematic errors of instruments and techniques themselves.In this study,bioinformatics was used to explore the potential of cross-kingdom regulation of plant miRNAs.In this paper,a method for identification and regulatory analysis of plant-derived miRNAs based on large-scale expression data of human or animals was constructed,and the data of human blood and other small RNAs were analyzed using this method.The following main results were obtained:(1)ePmiRNA?finder,an analytical tool was develeloped for identification and analysis of plant miRNAs in human and animal small RNA high-throughput sequencing data with strict standard and multiple dimensions.(2)The relationship between kidney disease and diet habit is close.139 small RNA data were collected from the blood of 72 clinical kidney transplant patients,and 331 plant miRNA sequences were identified using ePmiRNA?finder.We also profiled 41 blood exosome samples from 22 patients with acute immune rejection and compared them to 21 samples from 11 patients with stable allograft function to explore possible roles of the functional plant miRNAs.Three plant miRNA specifically expressed in the blood samples of immune-rejection patients after kidney transplantation targeted genes that enriched in immune-related pathways such as immune response and T cell activation.(3)To clarify whether different diets(herbivorous,omnivorous,and carnivorous)lead to different plant miRNA uptake,421 small RNA sequencing datasets from human body fluids and tissues were analyzed and compared with samples from other mammals.The expression and quantity of plant miRNAs identified in human blood small RNA sequencing samples by ePmiRNA?finder were significantly lower than that of herbivorous bovine,no significant difference was found between them and omnivorous mice,and significantly higher than that of carnivorous seal and negative control Rhodobacter sphaeroides(known to contain no plant miRNAs).Plant miRNAs were also commonly detected in human body fluid and tissue samples,and their expression profiles show fluid/tissue specificity.This study proves that plant miRNAs ingested through diet can be detected in human body,and it also indicates that plant miRNAs have the potential to participate in immune regulation after kidney transplantation.This study promotes the understanding of cross-kingdom regulation of plant miRNAs and provides a new theoretical reference for clinical dietary therapy.