Cells are extremely small. And yet they are every bit as complex as a major modern city, each with its specialized districts and transportation routes, along which travel proteins, nutrients, bits of RNA, etc.
Éric Lécuyer of the Montreal Clinical Research Institute studies the way RNAs are transported within cells. RNA, or ribonucleic acid, is similar to its brother DNA: it is a long molecular strand made up of a chain of smaller molecules called nucleotides. In the heart of the cell, the nucleus, reside the long filaments of DNA. This is where the genetic information is stored, and when the cell needs this information, a section of DNA is “photocopied” (more accurately, “transcribed”), producing a strand of RNA that is able to leave the nucleus and be delivered elsewhere in the cell.
“This RNA has a mission,” Eric Lécuyer explains. “And it needs to go to a specific place inside the cell to accomplish it. There is one section in the nucleotide sequence of an RNA molecule whose function is to ensure safe delivery; it is a sort of “postal code” that can be recognized by different structures and allows the RNA to travel to exactly where it is needed.”
With the aid of high-resolution imaging techniques and functional genomics, the molecular biologist and his team are unveiling the molecular mechanisms that control RNA targeting and their impact on cellular organization. Once the “postal code” system is properly understood, it can be used to precisely target the spot where therapeutic molecules are intended to act.
This knowledge could be used in the treatment of genetic diseases. “Take myotonic dystrophy, for example, which is highly prevalent in the Saguenay-Lac-Saint-Jean region,” the researcher says. “We know that it is caused by the formation of aberrant RNA that accumulates in clusters in the cell nucleus and causes disturbances. If we knew the precise “postal code” for this region of the nucleus, we could designate a therapeutic molecule that travels to this exact location and solves the problem. Similarly, other molecules could target mitochondria, the Golgi apparatus, and so on.
Breaking with more traditional approaches, such techniques for delivering drugs into cells could be the first major step towards curing major human diseases, such as Alzheimer’s, Parkinson’s, MS, and so on. We just need to know the right postal code.