History of safe use of small RNAs in food

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The small RNA compounds in our food are in the news:
What’s the News: It’s no secret that having lunch messes with your biochemistry. Once that sandwich hits your stomach, genes related to digestion have been activated and are causing the production of the many molecules that help break food down. But a new study suggests that the connection between your food’s biochemistry and your own may be more intimate than we thought. Tiny RNAs usually found in plants have been discovered circulating in blood, and animal studies indicate that they are directly manipulating the expression of genes.
What’s the Context:
MicroRNAs, or miRNAs, are molecules involved in regulation of  gene expression, the transcription of genes into proteins. miRNAs bind to the  messenger RNAs that ferry genetic information from DNA to the  ribosomes, which translate messenger RNAs into proteins.
When a miRNA binds a messenger RNA, it keeps it from being translated, thus preventing that gene from being expressed.
How the Heck:
This team of researchers at Nanjing University had been studying the miRNAs that circulate in human blood and were surprised to find that some of the miRNAs weren’t homegrown but instead came from plants. One of the most common plant miRNAs was from rice, a staple of their Chinese subjects’ diets. Intrigued, they confirmed with a variety of tests in mice that the miRNA, which, in its native environs, usually regulates plant development, was definitely coming from food….more at link to Discover Magazine
What’s not well known is that small RNA molecules identical to those in humans and animals are common in our food. There is a history of safe use of miRNA and siRNA in our diet. This is documented in the 2009 paper by Ivashuta and colleagues:
Endogenous small RNAs in grain: semi-quantification and sequence homology to human and animal genes.
Abstract
Small interfering RNAs (siRNAs) and microRNAs (miRNAs) are effector molecules of RNA interference (RNAi), a highly conserved RNA-based gene suppression mechanism in plants, mammals and other eukaryotes. Endogenous RNAi-based gene suppression has been harnessed naturally and through conventional breeding to achieve desired plant phenotypes. The present study demonstrates that endogenous small RNAs, such as siRNAs and miRNAs, are abundant in soybean seeds, corn kernels, and rice grain, plant tissues that are traditionally used for food and feed. Numerous endogenous plant small RNAs were found to have perfect complementarity to human genes as well as those of other mammals. The abundance of endogenous small RNA molecules in grain from safely consumed food and feed crops such as soybean, corn, and rice and the homology of a number of these dietary small RNAs to human and animal genomes and transcriptomes establishes a history of safe consumption for dietary small RNAs.
PMID: 19068223 [PubMed – indexed for MEDLINE] Ivashuta SI, Petrick JS, Heisel SE, Zhang Y, Guo L, Reynolds TL, Rice JF, Allen E, Roberts JK.
Food Chem Toxicol. 2009 Feb;47(2):353-60. Epub 2008 Nov 27.

REPOSTED FROM GMO PUNDIT Blog.

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David Tribe is an applied geneticist, teaching graduate/undergrad courses in food science, food safety, biotechnology and microbiology at the University of Melbourne.