Genome complexity: role of microRNA (Introduction)

by David Turell , Tuesday, November 15, 2022, 19:47 (521 days ago) @ David Turell

New finding in mice:

https://www.the-scientist.com/news-opinion/micrornas-can-boost-gene-expression-study-70759

"MicroRNAs—snippets of nucleic acids a couple dozen base pairs in length—are so small that they went unnoticed for decades despite wielding enormous influence in our cells. It’s now known that they suppress the expression of thousands of genes through a process called RNA interference, in which they bind to messenger RNAs (mRNAs) and prevent their translation. But a study published November 9 in ACS Central Science finds that microRNAs (miRNAs) can also amplify gene expression.

“'It changes the landscape of microRNA,” Lara Mahal, a chemist at the University of Alberta in Canada tells The Scientist. “There isn’t one mode of microRNA regulation: There are two.”

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"They discovered that while the miRNAs that interact with ST6GAL2 downregulate its expression, those that interact with ST6GAL1 boost its expression and therefore increase levels of 2,6-sialic acid attachment. “We were floored. We thought it was a mistake,” says Mahal.

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"Mahal believes that miRNA-mediated upregulation may have gone largely unnoticed because most groups tend to focus on transcripts that are far more abundant. When there are lots of copies of a protein being made, its effects can be straightforwardly fine-tuned by metering translation. But for genes already expressed at low levels, like the ones that regulate glycosylation, downregulation doesn’t make as much biological sense, she says.

“'It’s an exciting study,” says Pinar Uysal Onganer, a cancer biologist at the University of Westminster in the UK who was not involved in the work. Similar high-throughput studies are essential for validating miRNA interactions, enabling researchers to make better predictions of their effects, she says."

Comment: I don't understand the surprise. In biological systems, what is sent up. most also be sent down to maintain equilibrium. God makes complete designs.