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Archive - Mar 16, 2011

Using Light to Move Molecules in Living Cells

Using a light-triggered chemical tool, Johns Hopkins scientists report that they have refined a means of moving individual molecules around inside living cells and sending them to exact locations at precise times. This new tool, they say, gives scientists greater command than ever in manipulating single molecules, allowing them to see how molecules in certain cell locations can influence cell behavior and to determine whether cells will grow, die, move or divide. A report on the work was published in the January 12, 2011 issue of the Journal of the American Chemical Society. Studying how just one signaling molecule communicates in various parts of a living cell has posed a challenge for scientists investigating how different interactions influence cell behavior, such as the decision to move, change shape or divide. "By using one magical chemical set off by light, we modified our previous technique for moving molecules around and gained much more control," said Dr. Takanari Inoue, assistant professor of cell biology and member of the Center for Cell Dynamics in the Institute for Basic Biomedical Sciences. "The advantage of using light is that it is very controllable, and by confining the light, we can manipulate communication of molecules in only a tiny region of the cell," he said. Specifically, the Hopkins team designed a way to initiate and spatially restrict the molecular interactions to a small portion of the cell by attaching a light-triggered chemical to a bulky molecule, the bond between which would break when researchers shined a defined beam of ultraviolet light on it. This enabled the chemical to enter the cell and force two different and specific proteins in that cell to mingle when they otherwise wouldn't.

Nanopolymer Used to Screen for Kinase Inhibitors

A Purdue University scientist's nanopolymer would make it easier and cheaper for drug developers to test the effectiveness of a widely used class of cancer inhibitors (kinase inhibitors). Dr. W. Andy Tao, an associate professor of biochemistry analytical chemistry and a member of the Purdue Center for Cancer Research team, created the Purdue-patented pIMAGO nanopolymer that can be used to determine whether cancer drugs have been effective against biochemical processes that can lead to cancer cell formation. The nanopolymers would attach themselves to target proteins that would later be detected by a relatively simple laboratory procedure called chemiluminescence. Tymora Analytical, a company Tao started in the Purdue Research Park, will manufacture the pIMAGO nanopolymers. The 'p' stands for phosphor, and the IMAGO comes from the Greek word for image. Tao's pIMAGO nanopolymers are coated in titanium ions and would attract and bond with phosphorylated proteins, ones in which a phosphate group has been added to a protein activating an enzyme called kinase. Kinase, when overactive, is known to cause cancer cell formation, and many cancer drugs are aimed at inhibiting kinase activity. “It is universal. You can detect any kind of phosphorylation in a protein," said Tao, whose findings were reported online on March 11, 2011, in the journal Analytical Chemistry. "It is also cheaper and would be more widely available." The nanopolymers would be added to a solution of proteins, a chemical agent to start phosphorylation and a drug to inhibit kinase activity. Phosphorylated proteins would only be present if the drug is ineffective. Avidin-HRP - the protein Avidin bound with the enzyme horseradish peroxidase - would be added. Avidin would bind with a vitamin B acid called biotin that is also on the nanopolymers' surfaces.

Some Blind “See” with Their Ears

Dr. Olivier Collignon of the University of Montreal's Saint-Justine Hospital Research Centre compared the brain activity of people who can see and people who were born blind, and discovered that the part of the brain that normally works with our eyes to process vision and space perception can actually rewire itself to process sound information instead. The research was undertaken in collaboration with Dr Franco Lepore of the Centre for Research in Neuropsychology and Cognition and was published in the March 15, 2011 issue of PNAS. The research builds on other studies which show that the blind have a heightened ability to process sounds as part of their space perception. "Although several studies have shown occipital regions of people who were born blind to be involved in nonvisual processing, whether the functional organization of the visual cortex observed in sighted individuals is maintained in the rewired occipital regions of the blind has only been recently investigated," Dr. Collignon said. The visual cortex is responsible for processing sight. The right and left hemisphere of the brain have one each. They are located at the back of the brain, which is called the occipital lobe. "Our study reveals that some regions of the right dorsal occipital stream do not require visual experience to develop a specialization for the processing of spatial information and are functionally integrated in the preexisting brain network dedicated to this ability." The researchers worked with 11 individuals who were born blind and 11 who were not. Their brain activity was analyzed via MRI scanning while they were subjected to a series of tones. "The results demonstrate the brain's amazing plasticity," Dr. Collignon said.