25 June 2008

Quantum Bullets for Rapid Fire Gene Silencing

Scientists at the University of Washington Seattle, and Emory University have developed a rapid method of silencing gene expression by using quantum dots attached to small interfering RNA (si-RNA). The quantum dots carried the si-RNA into the cytoplasm, where it interacted with messenger RNA (mRNA) to prevent translation of genetic messages into proteins.
Quantum dots were dramatically better than existing techniques at stopping gene activity. In experiments, a cell's production of a test protein dropped to 2 percent when siRNA was delivered with quantum dots. By contrast, the test protein was produced at 13 percent to 51 percent of normal levels when the siRNA was delivered with one of three commercial reagents, or reaction-causing substances, now commonly used in laboratories.

Central to the finding is that fluorescent quantum dots allow scientists to watch the siRNA's movements. Previous siRNA trackers gave off light for less than a minute, while quantum dots, developed for imaging, emit light for hours at a time. In the experiments the authors were able to watch the process for many hours to track the gene-silencer's path.

The new approach is also five to 10 times less toxic to the cell than existing chemicals, meaning the quantum dot chaperones are less likely to harm cells. The ideal delivery vehicle would have no effect; the only biological change would be siRNA blocking cells' production of an unwanted protein. __Source_via_NextBigFuture
One key to the quantum dots ability to penetrate the cell wall so effectively, was the use of a "proton sponge" that coated the dots, giving them a positive charge which neutralised the negative charge of the siRNA.

This approach to influencing gene expression is temporary, but is typically easier than trying to change the genome--either genetically or epigenetically. This reversibility is a positive feature for short term gene silencing for specific purposes such as pre and post operative situations, serious acute trauma, shock, sepsis, or rehabilitation from severe illness or injury. Many more uses for this tool will crop up if its safety and efficacy remain high as reported.

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Blogger Snake Oil Baron said...

Even if safety concerns do develop the information that even temporary silencing in vitro can provide will no doubt prove useful in treatments that do not require using the dots. And using temporary silencing to prepare cells for specific purposes before cloning and reinserting might eliminate the need for having the dots used in the patient in some therapies. Fascinating stuff.

Wednesday, 25 June, 2008  
Blogger IConrad said...

I wonder if this could be used to induce heightened gene expression or to induce the expression of recessive genes as well as suppressing expression...

Wednesday, 25 June, 2008  
Blogger al fin said...

Conrad, there are ways that siRNA might be used to enhance gene expression of specific genes. It will take time to work them out.

Think of it as just one therapeutic approach among many for influencing gene expression--as the Baron implies. Other modalities would probably work better for enhancing gene expression, especially if a permanent alteration is needed.

Friday, 27 June, 2008  

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