Lights, Cells, Action!
One of the best ways to really see something is to turn on the lights. Amy Palmer, assistant professor in the Department of Chemistry and Biochemistry and Biofrontiers Institute faculty member, is the kind of professor that can shine a light on subjects for her students, and shine a light on the cellular subjects in her lab.
Shining a light was the kernel of the idea behind fluorescent proteins: proteins that absorb energy at a specific wavelength and re-emit the energy at a different wavelength. Osamu Shimomura discovered the first fluorophore, called the green fluorescent protein (GFP), in jellyfish. GFP was then popularized and turned into a useful tool for cell biology by Martin Chalfie and Roger Tsien. Together, the three scientists shared the Nobel Prize in chemistry in 2008 for their contributions. GFP gave scientists the ability to put these glow-in-the-dark molecules in cells and living organisms and watch action within cells that had never been seen.
“Snapshots of a football game won’t tell you how to play the game,” says Palmer, “Fluorescent proteins allow us to watch the game while it is in motion.”
Palmer’s group is developing tools and technologies around these pretty proteins, which now come in a rainbow of colors in addition to the original jellyfish green. She recently attached fluorescent proteins to the Salmonella bacteria to follow it as it invaded a host organism with the hopes of learning how to prevent the bacteria from taking over and wreaking havoc.
Palmer’s next target is not animal, not vegetable…it’s a mineral. Zinc is an essential trace mineral found in all humans, totaling almost two grams in the average adult. Next to iron, zinc is the most common mineral in the body and is found in every cell, and in large concentrations in the brain, retinas, pancreas and prostate.
Imbalances in zinc levels can cause a myriad of troubles, from Alzheimer’s to diabetes to prostate cancer. In addition, zinc plays important roles in growth and reproduction; taste, vision and smell; and even proper insulin and thyroid function. Zinc deficiency is a worldwide challenge causing problems ranging from stunted growth to fatal diseases.
Palmer is developing fluorescent probes that can attach to zinc. Defining the location of zinc and how it fluctuates in an organism is the first step in knowing how cells regulate it, and how we can regulate it in patients that have imbalances. For example, prostate cancer is difficult to diagnose and predict how it will respond to treatment. By measuring zinc levels, scientists may be able to predict the aggressiveness of the tumors and give a more accurate prognosis of the disease.
“We know very little about what zinc is doing at the cellular level,” says Palmer. “Fluorophores allow us to see how this metal is playing a role in some diseases like prostate cancer and diabetes.” She is aiming for a zinc-tracking technique to catch diseases early in their processes, but don’t expect to be injected with glow-in-the-dark proteins at your next doctor’s visit.
“There isn’t a clinical use for fluorescent proteins right now,” says Palmer. “There isn’t a machine for them that a doctor would use to look inside your body. What makes these proteins special is looking at what happens at the cellular level of an organism. We can see into cells and witness what an X-ray or MRI machine cannot. That fundamental level of understanding is going to lead us to bigger solutions.”