The disease originates when genetic mutations in the FMRP gene, which lies on the X chromosome, cause FMRP not to be produced. But unlike the well-studied Down syndrome, which occurs when a portion of a chromosome is duplicated in the womb, much remains unclear about the molecular basis of fragile X syndrome.
"The problem of fragile X is intriguing, because the loss of a single protein causes a variety of behavioral and physical changes," says Jennifer Darnell, Ph.D., lead author of one of the Cell reports and a research assistant professor at Rockefeller. "Before this, the consequences of losing the fragile X mental retardation protein on other brain proteins was unknown."
Previously, it was known that FMRP, first identified a decade ago, binds to messenger RNA (mRNA) molecules - which carry genetic information (DNA) from a body cell's nucleus to its protein-making machinery - yet the specific mRNAs involved as well as the overall purpose of this protein remained elusive.
Now, the researchers present several important clues, which together
suggest that FMRP may turn up or down the production of certain brain
proteins by binding to their mRNA molecules, and thus influencing the
cell's protein-making machinery. This type of protein regulation is a
crucial aspect of every cell's life, and in the case of brain cells, is
essential for learning and memory formation. A key feature of the current
work is the identification of the specific mRNAs that FMRP binds to, as
Contact: Whitney Clavin