A Real Time Look At Interactions Between RNA And Proteins

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A Real Time Look At Interactions Between RNA And Proteins

http://www.medicalnewstoday.com/medicalnews.php?newsid=36799

For the first time, researchers can now peer inside intact cells to

not only identify RNA-binding proteins, but also observe-in real-time-

the intricate activities of these special molecules that make them

key players in managing some of the cell's most basic functions.

Researchers at the University of Pennsylvania School of Medicine who

developed the new technology see this advance as one of the next

logical steps in genomics research. Senior author Eberwine,

PhD, Professor of Pharmacology at Penn, and colleagues published

their research this week in the Proceedings of the National Academy

of Sciences.

" Now we have a workable system to understand all aspects of RNA

metabolism in a cell, " say Eberwine. " For the first time, we can

study how manipulation of cellular physiology, such as administering

a drug, changes RNA-binding protein and RNA interactions. This

technology allows us to see that in real time in real cells. "

RNA is the genetic material that programs cells to make proteins from

DNA's blueprint and specifies which proteins should be made. There

are many types of RNA in the cells of mammals, such as transfer RNA,

ribosomal RNA, and messenger RNA-each with a specific purpose in

making and manipulating proteins.

The workhorses of the cell, RNA-binding proteins regulate every

aspect of RNA function. Indeed, RNA is transported from one site to

another inside the cell by RNA-binding proteins; RNA is translated

into protein with the help of RNA-binding proteins, and RNA-binding

proteins degrade used RNA. " They're really the master regulators of

expression in the cell, " says Eberwine.

Using whole neurons from rodents, the researchers were able to

identify RNA interactions in live cells. In collaboration with Ûlo

Langel from Stockholm University, the Penn investigators devised a

many-talented molecule that does not get broken down by enzymes once

inside a live cell. One end of the molecule, called a peptide nucleic

acid (PNA), has a cell-penetrating peptide called transportan 10 to

first get the PNA through the cell membrane. Once in the cell, the

PNA binds to a specific target messenger RNA (mRNA). There is also a

compound on the molecule that can be activated by light and will

cross-link the PNA to whatever protein is nearby. The researchers

isolated an array of proteins from the complex of the PNA, the

targeted mRNAs, and associated RNA-binding proteins. The cells are

then broken apart and the proteins that interact with the mRNA are

identified with a mass spectrometer.

With their system, the researchers are trying to identify RNA-binding

proteins that bind RNAs of interest-such as those involved in the

targeting, degradation, and translation of RNAs into proteins. Once

identified, the Eberwine team uses another technology they developed

to find the other RNA cargos that bind to that RNA-binding protein.

These are other RNAs that likely co-regulate RNAs associated with

disease.

The research was supported by grants from the National Institutes of

Health, the Swedish Science Foundation, and the European Community.

Study coauthors are Zielinski, Tiina Peritz, Jeanine

Jochems, Theresa Kannanayakal, and Miyashiro, from Penn, and

Kalle Kilk, Emilia Eiriksdóttir, and Ûlo Langel from Stockholm

University, Sweden. This release can be found at

http://www.uphs.upenn.edu/news/