Molecular probes identify changes in fibronectin that may lead to disease

April 24, 2012
Molecular probes displaying the LNLPHG and RFSAFY peptide sequences showed the greatest binding affinity to fibronectin fibers and the greatest efficiency in discriminating between relaxed and strained fibers. On extracellular matrix assembled by primary lung fibroblasts, LNLPHG preferentially attached to relaxed fibronectin fibers (top row), whereas RFSAFY bound to strained fibers (bottom row). (The scale bar is 20 microns) Credit: Georgia Tech/Thomas Barker

Fibronectin plays a major role in wound healing and embryonic development. The protein, which is located in the extracellular matrix of cells, has also been linked to pathological conditions including cancer and fibrosis.

During , fibronectin are believed to experience mechanical forces that strain the fibers and cause dramatic structural modifications that change their . While understanding the role of fibronectin strain events in development and disease progression is becoming increasingly important, detecting and interrogating these events is difficult.

In a new study, researchers identified molecular probes capable of selectively attaching to fibronectin fibers under different strain states, enabling the detection and examination of fibronectin strain events in both culture and living tissues.

"The mechano-sensitive molecular probes we identified allow us to dynamically examine the relevance of events within the natural cellular and correlate these events with specific alterations in fibronectin associated with the progression of disease," said Thomas Barker, an assistant professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

The study was published on April 23, 2012 in the online early edition of the journal . Barker worked on the study with Georgia Tech graduate student Lizhi Cao and Harry Bermudez, an assistant professor in the University of Massachusetts Amherst Department of Polymer Science and Engineering. The research was supported by the National Institutes of Health.

Staining of fibronectin-targeting molecular probes displays the LNLPHG (blue) and RFSAFY (red) peptide sequences on prepared living lung slices. The probes did not attach to the same fiber, which confirmed their ability to selectively discriminate strained or relaxed regions within a fibronectin fiber network. (The scale bar is 20 microns) Credit: Georgia Tech/Thomas Barker

Researchers have hypothesized that mechanical forces emanating from cells may partially unfold fibronectin and regulate what proteins bind to it. While simulation and tissue culture experiments support this hypothesis, direct evidence that such molecular events occur in has not yet been presented, according to Barker.

A technique called intramolecular fluorescence resonance energy transfer (FRET) has been used to detect molecular strain events in fibronectin fibers, but the technique has limitations because it cannot be used on living tissues and requires the fibronectin to be chemically labeled.

"The molecular probes we identified can be used to map molecular strain events in native and living lung tissues," explained Barker. "The probes can also be used to study the mechanism by which cells control the that alter fibronectin's conformation, control the exposure of its binding sites and regulate cell signaling."

The researchers used a controlled fibronectin fiber deposition and extension technique to apply tension to the fibers and stretch them to 2.6 times their original length without significant breakage. Then they used a technique called phage display to identify peptides capable of discriminating fibronectin fibers under relaxed and strained conditions. The molecular probes displaying peptide sequences LNLPHG and RFSAFY showed the greatest binding affinity to fibronectin fibers and the greatest efficiency in discriminating between relaxed and strained fibers.

For proof-of-concept demonstrations, the researchers used the probes to discriminate fibronectin fibers within native extracellular matrix and mouse lung slices. LNLPHG preferentially attached to relaxed fibronectin fibers, whereas RFSAFY bound to strained fibers. The probes never attached to the same fiber, which confirmed their ability to selectively discriminate regions within a fibronectin fiber network.

"This study strongly suggests that fibronectin fibers under strain display markedly different biochemical signatures that can be used for the molecular-level detection of fibronectin fiber strain," explained Barker. "The data also show the potential for living tissue to be interrogated for mechano-chemical alterations that lead to physiological and pathological progression."

In the future, the researchers hope to use these fibronectin strain-sensitive probes to target therapeutics to fibronectin fibers based on their mechanical signature.

Explore further: Metastatic breast cancer hitches a free ride from the immune system

Related Stories

Metastatic breast cancer hitches a free ride from the immune system

February 10, 2012
Inflammatory breast cancer (IBC) is the most lethal form of breast cancer . It spreads easily through the lymphatic and blood vessels, forming metastasis which can lead to multi-organ failure. New research published in BioMed ...

Researchers find possible breakthrough to relieve pain following spinal cord injury

November 30, 2011
A collaborative research group – led by researchers at Cleveland Clinic – published findings that indicate a one-time injection immediately after spinal cord injury can limit pain for an extended period of time.

Recommended for you

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

'Smart' robot technology could give stroke rehab a boost

July 19, 2017
Scientists say they have developed a "smart" robotic harness that might make it easier for people to learn to walk again after a stroke or spinal cord injury.

Engineered liver tissue expands after transplant

July 19, 2017
Many diseases, including cirrhosis and hepatitis, can lead to liver failure. More than 17,000 Americans suffering from these diseases are now waiting for liver transplants, but significantly fewer livers are available.

Lunatic Fringe gene plays key role in the renewable brain

July 19, 2017
The discovery that the brain can generate new cells - about 700 new neurons each day - has triggered investigations to uncover how this process is regulated. Researchers at Baylor College of Medicine and Jan and Dan Duncan ...

New animal models for hepatitis C could pave the way for a vaccine

July 19, 2017
They say that an ounce of prevention is worth a pound of cure. In the case of hepatitis C—a disease that affects nearly 71 million people worldwide, causing cirrhosis and liver cancer if left untreated—it might be worth ...

Omega-3 fatty acids fight inflammation via cannabinoids

July 18, 2017
Chemical compounds called cannabinoids are found in marijuana and also are produced naturally in the body from omega-3 fatty acids. A well-known cannabinoid in marijuana, tetrahydrocannabinol, is responsible for some of its ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.