What is it about?

After stroke, the brain is exposed to diverse infiltrating attacks. To fight this damage and effectively block immune over-reactions, the body recruits emergency control by declining blood cell microRNA levels and increasing transfer RNA fragments which can similarly block the expression of mRNAs carrying complementary sequences. This ‘changing of the guards’ process can limit the risk of pneumonia which endangers the stroke survivors’ life.

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Why is it important?

Stroke is the leading cause of death above the age of 70. Every year, 15 million world-wide stroke survivors need preventive care to avoid pneumonia, which threatens the life of 30% of them. We showed that after stroke, the body replaces the ‘regular' microRNA control over immune reactions with an ‘emergency’ shredding of pre-existing transfer RNA molecules (which regularly ignite protein synthesis) into microRNA-like chains that block excessive immune reactions.


Emergency states need special steps, as we have learned during the COVID-19 pandemic. The neurotransmitter acetylcholine operates in regular and acute states to balance immune functions via small RNA agents. It was amazing to reveal that the routine surveillance by microRNA controllers of acetylcholine signalling is replaced after stroke with an emergency control system that shreds transfer RNA chains and re-uses the fragments to minimize the immune risks.

Hermona Soreq

Read the Original

This page is a summary of: Transfer RNA fragments replace microRNA regulators of the cholinergic poststroke immune blockade, Proceedings of the National Academy of Sciences, December 2020, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2013542117.
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