Pediatric researchers have discovered a new biological pathway in which small segments of RNA, called microRNA, help protect red blood cells from injury caused by chemicals called free radicals. The microRNA seems to have only a modest role when red blood cells experience normal conditions, but steps into action when the cells are threatened by oxidant stress.
Led by hematologist Mitchell Weiss, M.D., Ph.D., of The Children's Hospital of Philadelphia, the current study describes how a particular microRNA fine-tunes gene activity by acting on an unexpected signaling pathway.
The study appears in the August 1 issue of the journal Genes & Development, simultaneously with a similar study of microRNAs and red blood cells by a University of Texas team led by Eric Olson, Ph.D. The two studies reinforce each other, said Weiss.
MicroRNAs are single-stranded molecules of ribonucleic acid (RNA) averaging only 22 nucleotides long. Scientists estimate that 500 to 1000 microRNAs exist in the human genome. First characterized in the early 1990s, they received their current name in 2001. Over the past decade, scientists have increasingly recognized that microRNAs play a crucial role in regulating genes, most typically by attaching to a piece of messenger RNA and blocking it from being translated into a protein, but many details remain to be discovered.
"Although microRNAs affect the formation and function of most or all tissues, for most microRNAs, we don't know their precise mechanisms of action," said Weiss. "In this case we already knew this microRNA, called miR-451, regulates red blood cells in zebrafish and mice, and because it is highly conserved in evolution, we presume it operates in humans as well. But its functional roles were poorly understood."
By investigating how microRNAs influence red blood cell development, Weiss and colleagues aimed to understand how such development goes wrong in hemolytic anemia, in whic
|Contact: John Ascenzi|
Children's Hospital of Philadelphia