Shining Light (Literally) On The Workings Of Cells

Jul 28, 2011

Scientists would like to know more about how cells work. But seeing what's happening inside a cell isn't easy. It's dark in there, and even if you shine a light, many of the critical chemical reactions are invisible.

Now, a team of researchers has found a way to reveal the invisible by attaching what amounts to a reflective tag to a chemical called RNA, a close relative of DNA. Molecules made of RNA have a variety of important jobs inside cells and frequently, doing those jobs requires the RNA to shuttle from one part of the cell to another.

Samie Jaffrey and his colleagues at Weill Cornell Medical School in New York wanted to track those movements. So they came up with a way to attach a kind of chemical tag to the RNA — a tag that will light up when you shine the right wavelength of light on it.

Jaffrey says being able to see how the RNA is moving inside cells should answer a lot of important questions about what the chunks of RNA inside cells are up to, like: "When do they move, in response to what signals in cells? And how is their movement affected in diseases?" This information "will give us more insight into how those RNAs are linked to the disease process," Jaffrey says.

One nice feature of the new technique is that you can watch the RNA move in real time, so you can make movies of RNA's travel around a cell. (See the video at the left).

Sometimes, RNA has to travel a surprisingly long distance, as is the case in certain nerve cells — such as those in the neck of a giraffe. Jaffrey's technique would allow scientists to watch that movement.

Philip Santangelo, a professor of biomedical engineering at Georgia Tech, says the new imaging technique should also be helpful in understanding how viruses cause disease. Many viruses make extensive use of RNA when they infect cells.

"Visualizing RNA is intrinsically important for lots and lots of different disease, and for an understanding of the way cells function," he says.

There are already some techniques for visualizing RNA in cells. Diana Bratu, an assistant professor of biophotonics at Hunter College in New York, says she and others have developed ways to light up RNA, but they've had problems: "Delivery of previous techniques into living cells has been difficult," she says.

She says Samie Jaffrey's new approach should solve those difficulties. "I will certainly contact Samie to incorporate it in my own research."

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Transcript

MICHELE NORRIS, host: Scientists would like to know more about how cells work, but seeing what's happening inside a cell is not easy; it's dark in there, and many critical chemical reactions are invisible. Now, a team of researchers has found a way to reveal the invisible. They do it by attaching what amounts to a reflective stripe to a key chemical component of cells. NPR's Joe Palca has the story.

JOE PALCA: The key chemical is called RNA, a close relative of DNA. Molecules made of RNA have a variety of important jobs inside cells and frequently doing those jobs requires the RNA to shuffle from one part of the cell to another. Samie Jaffrey and his colleagues at Weill Cornell Medical School in New York wanted to track those movements. So, they came up with a way to attach a kind of chemical tag to the RNA.

Dr. SAMIE JAFFREY: A simple tag that would allow us to see the RNA using fluorescence microscopy.

PALCA: It's like sneaking up on it an attaching a light to its backside.

JAFFREY: I think so, yeah. I think that's what we basically want to do.

PALCA: It took a number of tries, but as he reports in this week's edition of the journal Science, Jaffrey and his colleagues found a way to attach something called a fluorophore to a chunk of RNA. A fluorophore is a molecule that will glow when you shine a light on it and look with the right kind of microscope. Jaffrey says being able to see how the RNA is moving inside cells should answer a lot of important questions about what the chunks of RNA inside cells are up to.

JAFFREY: When do they move in response to what signals in cells and how is their movement affected in diseases will give us more insight into how those RNAs are linked to the disease process.

PALCA: One nice feature of the new technique is that you can watch the RNA move in real time, so you can watch movies of RNA travel around a cell.

JAFFREY: Which is exactly what we do.

PALCA: Jaffrey says there's a kind cellular railroad that the RNAs move along. Now, scientists are able to watch that happening. Philip Santangelo of the Georgia Institute of Technology says the new imagining technique should also be helpful in understanding how viruses cause diseases. Many viruses make extensive use of RNA when they infect cells.

PHILIP SANTANGELO: Visualizing RNA intrinsically is important for lots and lots of diseases of different disease, and again a fundamental understanding of the how cells function too.

PALCA: There are other techniques for visualizing RNA in cells. Diana Bratu is an assistant professor of biophotonics at Hunter College in New York. She and others have developed ways to light up RNA, but they've had problems.

DIANA BRATU: Delivery of previous techniques into living cells have been difficult.

PALCA: Bratu says Samie Jaffrey's new approach should solve those difficulties.

BRATU: I will certainly contact Samie through - to definitely incorporate it in my own research.

PALCA: Can't have a much stronger endorsement than that. Joe Palca, NPR News, Washington. Transcript provided by NPR, Copyright National Public Radio.