microRNA

noun

mi·​cro·​RNA ˌmī-krō-ˌär-(ˌ)en-ˈā 

variants or less commonly micro-RNA

genetics

: a short segment of RNA that suppresses gene expression by binding to complementary segments of messenger RNA and interfering with the formation of proteins by translation (see translation sense 2)

The 2006 Nobel Prize honored the discovery of RNA interference … and RNAi has helped shed light on the fact that cells naturally use RNA molecules just 20 to 22 nucleotides long, dubbed microRNAs, to regulate gene expression.

—Jennifer Couzin

called also miRNA

Examples of microRNA in a Sentence

Recent Examples on the Web

Scientists are studying various ways to deliver microRNA treatments to their specific target cells. —Andrea Kasinski, The Conversation, 7 Oct. 2024

Regulus Therapeutics works on therapies that target what’s called microRNA, a type of molecule that helps control the function of cells. —Deirdre Hipwell and Naomi Kresge, Los Angeles Times, 2 May 2025

Regulus continues to advance its internal discovery pipeline to identify potential product candidates and is focused on expanding its intellectual property estate to protect its microRNA therapeutics. —Quartz Intelligence Newsroom, Quartz, 13 Mar. 2025

Native to southwest China, pandas spend up to 16 hours a day devouring bamboo, absorbing a genetic material called microRNA (miRNA) into their bloodstream, according to research published Friday in the journal Frontiers. —Chris Lau, CNN, 28 Feb. 2025

This concept was reinforced by the Nobel committee, which awarded the Nobel Prize in Physiology or Medicine to the researchers who discovered microRNA (opens a new tab). —Quanta Magazine, 18 Dec. 2024

Delivering microRNA to cells One reason why delivering microRNA treatments into cells is difficult is because microRNA treatments need to be delivered specifically to diseased cells while avoiding healthy cells. —Andrea Kasinski, The Conversation, 7 Oct. 2024

This means that microRNA helps control when and how much a particular protein should be made. —Paul Smaglik, Discover Magazine, 30 Oct. 2024

Fletcher said the most advanced studies to date are reviewing how microRNA approaches might help treat skin cancer, but no drugs have yet been approved. —Daniel Niemann, Los Angeles Times, 7 Oct. 2024

Word History

First Known Use

2001, in the meaning defined above

Medical Definition

microRNA

noun

mi·​cro·​RNA ˌmī-krō-ˌär-en-ˈā 

variants also micro-RNA

: a short segment of RNA that suppresses gene expression by binding to complementary segments of messenger RNA and interfering with the formation of proteins during translation

These microRNAs (miRNAs)—21 to 25 nucleotides in length—are negative regulators of gene expression.

—Paul S. Meltzer, Nature

called also miRNA