Light-Based 'Remote Control' Developed for Proteins Inside Cells

ScienceDaily (Nov. 8, 2012) — Scientists at Stanford University have developed an intracellular remote control: a simple way to activate and track proteins, the busiest of cellular machines, using beams of light.

The new method, described in a paper to be published Nov. 9 in Science, will let researchers shine light on a specific cell region to quickly activate a protein in that area, producing an unusually fine-grained view of the location and timing of protein activity. In addition, the method may eventually enable physicians to direct the movement and activity of stem cells used to treat injury or illness in light-accessible body parts, such as the eye or skin. Stanford has filed a patent application for the work.

The method involves splicing two pieces of a specific fluorescent protein to other proteins of interest. The resulting hybrids -- called fluorescent, light-inducible proteins, or FLIPs -- have two interesting features: Not only are they turned on by light, but they also glow less brightly when activated, a change that provides an easy way to sense protein activity.

"It's sort of like having a garage door opener that also tells you if the garage door is open or closed," said Michael Lin, MD, PhD, an assistant professor of pediatrics and of bioengineering and the senior author of the paper. "I'm always driving out of my house, closing the garage door, and then wondering after I drive away if it's shut, so I have to drive back and check." If garage doors were like FLIPs, Lin would be spared his return trip, since these proteins not only turn on at the flip of a light switch, but also tell an observer that they're working. "One molecule can tell you where it is and what it's doing," said Lin.

The trick to the new method is that it uses pieces of a Velcro-like fluorescent protein called Dropna. In the dark, Dropna units adhere to each other and fluoresce. Under cyan-colored light, the units detach and begin to dim. Lin's team spliced a Dropna unit to each end of the proteins they wanted to study to make the FLIPs. In the dark, the Dropna units stuck together and physically blocked the active sites of the proteins under study. When cyan-colored light was shone on the proteins, the Dropna units fell apart, exposing the protein's active site so it could work. Under cyan light, the Dropna units also glowed less brightly, signaling that the FLIP was switched on.

It's easiest to build FLIPs from proteins that fold with both their head and tail ends near the active site, though the research team is now figuring out how to attach Dropna units to other parts of a protein, not just an end. With that modification, Lin anticipates that FLIPs could be created from most proteins that scientists want to investigate.

"For science geeks, this is very interesting in that it converges two exciting fields: biological sensing, which has been dominated by fluorescent proteins, and optogenetics, the use of light to investigate biology," Lin said.

In the past, scientists who specialized in biological sensing have tagged bits of the cellular machinery with fluorescent proteins to see where certain processes occurred in the cell. Separately, optogenetics experts -- using methods that originated at Stanford -- have figured out how to switch on specific neuron circuits with light. Lin's method combines advantageous features of both techniques, and is the first instance of optogenetics-type techniques being applied to individual proteins.

Outside the research lab, the method could be used to give directions to stem cells injected for therapeutic purposes. For instance, if the stem cells were engineered to contain FLIPs that control cell motility, a beam of light could then direct implanted stem cells to a particular location. Similarly, FLIPs and appropriately timed light beams could be used to control what a stem cell does when it reaches its destination.

"If you think about how we might want to use stem cells to regenerate tissues, we may need control over where cells go, when they proliferate and when they die," Lin said. At present, this application seems most likely for tissues at the body's surface, such as the eye and skin, because physicians would need to be able to deliver light to the treatment site.

http://www.sciencedaily.com/releases/2012/11/121108142744.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29

Hunting Neuron Killers in Alzheimer's and Traumatic Brain Injury

ScienceDaily (Nov. 9, 2012) — Sanford-Burnham researchers discovered that the protein appoptosin prompts neurons to commit suicide in several neurological conditions -- giving them a new therapeutic target for Alzheimer's disease and traumatic brain injury.

Dying neurons lead to cognitive impairment and memory loss in patients with neurodegenerative disorders-conditions like Alzheimer's disease and traumatic brain injury. To better diagnose and treat these neurological conditions, scientists first need to better understand the underlying causes of neuronal death.

Enter Huaxi Xu, Ph.D., professor in Sanford-Burnham's Del E. Webb Neuroscience, Aging, and Stem Cell Research Center. He and his team have been studying the protein appoptosin and its role in neurodegenerative disorders for the past several years. Appoptosin levels in the brain skyrocket in conditions like Alzheimer's and stroke, and especially following traumatic brain injury.

Appoptosin is known for its role in helping the body make heme, the molecule that carries iron in our blood (think "hemoglobin," which makes blood red). But what does heme have to do with dying brain cells? As Xu and his group explain in a paper they published recently in the Journal of Neuroscience, excess heme leads to the overproduction of reactive oxygen species, which include cell-damaging free radicals and peroxides, and triggers apoptosis, the carefully regulated process of cellular suicide. This means that more appoptosin and more heme cause neurons to die.

Not only did Xu and his team unravel this whole appoptosin-heme-neurodegeneration mechanism, but when they inhibited appoptosin in laboratory cell cultures, they noticed that the cells didn't die. This finding suggests that appoptosin might make an interesting new therapeutic target for neurodegenerative disorders.

What's next? Xu and colleagues are now probing appoptosin's function in mouse models. They're also looking for new therapies that target the protein.

"Since the upregulation of appoptosin is important for cell death in diseases such as Alzheimer's, we're now searching for small molecules that modulate appoptosin expression or activity. We'll then determine whether these compounds may be potential drugs for Alzheimer's or other neurodegenerative diseases," Xu explains.

Putting a stop to runaway appoptosin won't be easy, though. That's because we still need the heme-building protein to operate at normal levels for our blood to carry iron. In a previous study, researchers found that a mutation in the gene that encodes appoptosin causes anemia. "Too much of anything is bad, but so is too little," Xu says.

New therapies that target neurodegenerative disorders and traumatic brain injury are sorely needed. According to the CDC, approximately 1.7 million people sustain a traumatic brain injury each year. It's an acute injury, but one that can also lead to long-term problems, causing epilepsy and increasing a person's risk for Alzheimer's and Parkinson's diseases. Not only has traumatic brain injury become a worrisome problem in youth and professional sports in recent years, the Department of Defense calls traumatic brain injury "one of the signature injuries of troops wounded in Afghanistan and Iraq."

http://www.sciencedaily.com/releases/2012/11/121109111509.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29

Reactions to Everyday Stressors Predict Future Health

ScienceDaily (Nov. 2, 2012

Contrary to popular perception, stressors don't cause health problems -- it's people's reactions to the stressors that determine whether they will suffer health consequences, according to researchers at Penn State.

"Our research shows that how you react to what happens in your life today predicts your chronic health conditions and 10 years in the future, independent of your current health and your future stress," said David Almeida, professor of human development and family studies.

 "For example, if you have a lot of work to do today and you are really grumpy because of it, then you are more likely to suffer negative health consequences 10 years from now than someone who also has a lot of work to do today, but doesn't let it bother her."

Using a subset of people who are participating in the MIDUS (Midlife in the United States) study, a national longitudinal study of health and well being that is funded by the National Institute on Aging, Almeida and his colleagues investigated the relationships among stressful events in daily life, people's reactions to those events and their health and well being 10 years later.

Specifically, the researchers surveyed by phone 2,000 individuals every night for eight consecutive nights regarding what had happened to them in the previous 24 hours. They asked the participants questions about their use of time, their moods, the physical health symptoms they had felt, their productivity and the stressful events they had experienced, such as being stuck in traffic, having an argument with somebody, or taking care of a sick child.

"Most social-science surveys are based on long retrospective accounts of your life in the past month or maybe the past week," Almeida said. "By asking people to focus just on the past 24 hours, we were able to capture a particular day in someone's life. Then, by studying consecutive days, we were able to see the ebb and flow of their daily experiences."

The researchers also collected saliva samples from the 2,000 individuals at four different times on four of those eight days. From the saliva, they were able to determine amounts of the stress hormone, cortisol. They then linked the information they collected to data from the larger MIDUS study, including the participants' demographic information, their chronic health conditions, their personalities and their social networks.

"We did this 10 years ago in 1995 and again in 2005," Almeida said. "By having longitudinal data, not only were we able to look at change in daily experiences over this time but how experiences that were occurring 10 years ago are related to health and well being now."

The team found that people who become upset by daily stressors and continue to dwell on them after they have passed were more likely to suffer from chronic health problems -- especially pain, such as that related to arthritis, and cardiovascular issues -- 10 years later.

"I like to think of people as being one of two types," Almeida said. "With Velcro people, when a stressor happens it sticks to them; they get really upset and, by the end of the day, they are still grumpy and fuming. With Teflon people, when stressors happen to them they slide right off. It's the Velcro people who end up suffering health consequences down the road."

The results appear online in the current issue of Annals of Behavioral Medicine

According to Almeida, certain types of people are more likely to experience stress in their lives. Younger people, for example, have more stress than older people; people with higher cognitive abilities have more stress than people with lower cognitive abilities; and people with higher levels of education have more stress than people with less education.

"What is interesting is how these people deal with their stress," said Almeida. "Our research shows that people age 65 and up tend to be more reactive to stress than younger people, likely because they aren't exposed to a lot of stress at this stage in their lives, and they are out of practice in dealing with it. Younger people are better at dealing with it because they cope with it so frequently. Likewise, our research shows that people with lower cognitive abilities and education levels are more reactive to stress than people with higher cognitive abilities and education levels, likely because they have less control over the stressors in their lives."

While stress may be a symptom that a person's life is filled with hardship, it could also simply mean that the person is engaged in a wide variety of activities and experiences.

"If this is the case, reducing exposure to stressors isn't the answer," said Almeida. "We just need to figure out how to manage them better."

The National Institutes of Health provided funding for this research. Other authors on the paper include Susan Charles of the University of California at Irvine, Jennifer Piazza of California State University at Fullerton, and Martin Sliwinski and Jacquie Mogle, both at Penn State.

http://www.sciencedaily.com/releases/2012/11/121102205143.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29