Exogenous microRNAs in maternal food pass through placenta, regulate fetal gene expression

Zhang's group at Nanjing University reports that small non-coding RNAs
in maternal food can transfer through placenta to regulate fetal gene
MicroRNAs (miRNA) are a class of noncoding RNAs with lengths of
approximately 22 nucleotides that bind to target messenger RNAs to
inhibit protein translation. In previous studies, the same group has
found that plant miRNAs can enter into the host blood and tissues via
the route of food-intake. The food-derived exogenous miRNAs are
absorbed, packaged into microvesical (MV) and then secreted into
circulation by cells of animal GI tract. More importantly, once inside
the host, the food-derived exogenous miRNAs can regulate host physiology
by regulating host "target" genes in the cross-kingdom manner. In
support of this new concept, they have also found a plant microRNA,
MIR2911, which is enriched in honeysuckle, directly targets influenza A viruses (IAV) including H1N1, H5N1 and H7N9. Drinking of honeysuckle soup can prevent IAV infection and reduce H5N1-induced mice death.
Here, they report another surprising finding that exogenous plant miRNAs
and artificial synthetic small influence RNAs (siRNAs) can transfer
through the placenta and directly regulate fetus gene expression.
Firstly, exogenous plant miRNAs was detected in human umbilical cord
blood, amniotic fluid as well as animal fetuses with certain level. When
pregnant mice were administrated honeysuckle soup (the exogenous plant
microRNAs are physiological concentration in food), the plant MIR2911
was detected in fetus liver at a significant level. Finally, feeding
pregnant mice with synthetic alpha-fetoprotein (AFP, only expressed in
fetus liver) siRNA decreased significantly AFP mRNA and protein levels.
They have further demonstrated that MV- driven small RNAs are able to
pass through placenta.

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