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How muscles get stronger — and the nose knows

December 7, 2009

Scientists at Emory studying muscle repair have discovered an unexpected function for odorant receptors.

Odorant receptors’ best known functions take place inside the nose. By sending signals when they encounter substances wafting through the air, odorant receptors let us know what we’re smelling. Working with pharmacologist Grace Pavlath, graduate student Christine Griffin found that the gene for one particular odorant receptor is turned on in muscle cells during muscle repair.

The activation of the odorant receptor gene MOR23 is visible in muscle tissue in pink. Cell nuclei appear as blue.

The activation of the odorant receptor gene MOR23 is visible in muscle tissue in pink. Cell nuclei appear as blue.

Grace Pavlath, PhD

Grace Pavlath, PhD

Christine Griffin

Christine Griffin

“Normally MOR23 is not turned on when the tissue is at rest, so we wouldn’t have picked it up without looking specifically at muscle injury,” Pavlath says. “There is no way we would have guessed this.”

The finding could lead to new ways to treat muscular dystrophies and muscle wasting diseases, and also suggests that odorant receptors may have additional unexpected functions in other tissues.

While we’re on the topic of odorant receptors, a great article in November’s Howard Hughes Medical Institute Bulletin describes Emory psychiatrist Kerry Ressler’s work with Linda Buck when he was a graduate student.

From the article:

“I had never thought about smell a day in my life until I heard Linda give her talk,” Ressler says, still jazzed by the memory, “and I was absolutely blown away.” Buck had methodically identified about 1,000 odorant receptor (OR) genes and she outlined an orderly plan for decoding their function.

…Over the next three years, Ressler’s dissertation work contributed to the accomplishments that earned Buck the 2004 Nobel Prize in Physiology or Medicine, which she shared with HHMI investigator Richard Axel. Prominently displayed in Ressler’s Emory office is a framed picture of him with Buck at the Stockholm ceremony, both grinning broadly in formalwear.”

Ressler and his colleagues at Yerkes National Primate Research Center now study how fearsome memories become lodged in our brains. Since smell is often described as accessing the most primitive parts of the brain, the connection between Ressler’s past and present makes sense.

Kerry Ressler, MD, PhD, when he's not in Stockholm

Kerry Ressler, MD, PhD, when he's not in Stockholm -- Parker Smith / PR Newswire, © HHMI

qeastman 7 December 2009 News, Research , , , , , No Comments

Look, don’t touch – noninvasive biochemistry

October 12, 2009

Much of the time in biochemistry, when you want to know what’s happening inside a cell you have to break them open.

Fluorescent proteins are a great tool and deserved their Nobel Prize. But you have to convince your favorite cells to make the fluorescent proteins first. It’s possible to think of specialized non-invasive probes too: dyes that change color when they encounter calcium, for example.

Now imagine being able to decipher what’s going on inside cells simply by looking at them and watching the proteins and organelles shift in response to signals. That’s essentially what Yuhong Du and Haian Fu at the Emory Chemical Biology Discovery Center have been able to do.

They use an “optical biosensor” which puts cells in front of a reflective grating. Depending on how the grating reflects light, they can measure mass redistribution inside the cells.

How the optical biosensor works

How the optical biosensor works

With this technology, they could watch for responses as cancer cells responded to signals from EGFR (epidermal growth factor receptor).

Drugs such as gefitinib and erlotinib are supposed to block those growth signals in lung cancer cells, but not every cancer responds to them. These results suggest that the optical biosensor system could be used to screen for compounds that block EGFR and many other receptors, potentially speeding up the hunt for drugs against several diseases.

qeastman 12 October 2009 Research , , No Comments

Congrats to the telomere/ribosome Nobelists

October 7, 2009

Congratulations to Elizabeth Blackburn, Carol Greider and Jack Szostak for the 2009 Nobel Prize in medicine. The award is for their work on telomeres, the protective caps on the ends of chromosomes that shorten with every cell division and need specialized enzymes to be replenished.

Greider, Blackburn and Szostak discovered telomerase, the enzyme that copies the ends of chromosomes using a special RNA template. Telomerase is turned off in most human cells, but cancer cells often must reactivate it so that they can keep dividing like crazy.

The discovery of telomerase has led to new leads for potential anticancer drugs. This is a good example of the impact basic research can have on medicine, since the prize-winners were not thinking about anticancer drugs in the 1980s when they were doing their work.

Telomeres are specialized protective structures at the ends of chromosomes

Telomeres are specialized protective structures at the ends of chromosomes

The telomere trio’s work relates to several lines of research at Emory.

Immunologist Cornelia Weyand and her colleagues have shown that the telomeres of T cells are abnormally shortened in patients with rheumatoid arthritis. In effect, their cells’ chromosomes are prematurely aged. This result provides some hints on how to treat autoimmune diseases.

If blood-forming stem cells can’t keep their telomeres in shape, they can’t continue to regenerate the blood. Pathologist Hinh Ly’s research has made a connection between genetic defects in telomere maintenance and bone marrow failure syndrome in human patients.

Geneticists Christa Martin and David Ledbetter have been probing the relationship between mutations or recombination in the regions of the chromosome adjacent to telomeres and developmental disorders such as autism and mental retardation.

The 2009 Nobel Prize in Chemistry, awarded to Venki Ramakrishnan, Tom Steitz and Ada Yonath, has an even stronger connection to Emory. Christine Dunham, part of a growing contingent of crystallographers here, worked on ribosome structure in Ramakrishnan’s lab at the MRC.

The ribosome is a machine that decodes mRNA and produces protein step by step

The ribosome is a machine that decodes mRNA and produces protein step by step

She is examining the molecular details of how antibiotics and viruses perturb ribosome function.

What the two Nobels have in common is that they both honor work on molecular machines containing RNA, connections to the ancient, shadowy “RNA world“.

qeastman 7 October 2009 News, Research , , , , , , No Comments