FEB 23, 2015 11:44 AM PST

Crucial Protein Keeps the Heart Beating on Time

WRITTEN BY: Judy O'Rourke
The average heart beats 35 million times a year - 2.5 billion times over a lifetime. Those beats must be precisely calibrated; even a small divergence from the metronomic rhythm can cause sudden death. For decades, scientists have wondered exactly how the heart stays so precisely on rhythm even though it contains so many moving parts.

Now, researchers at the University of Maryland School of Medicine (UM SOM) have helped identify how a particular protein plays a central role in this astonishing consistency. This is the first time the mechanism has been described; the discovery could eventually help scientists treat heart problems that kill millions of people every year.

The researchers describe how myosin-binding protein C ("C protein") allows the muscle fibers in the heart to work in perfect synchrony.

For years, researchers have known that calcium acts as a trigger for the heartbeat, activating proteins that cause the sarcomeres - the fibrous proteins that make up heart muscle cells - to contract. W. Jonathan Lederer, MD, PhD, found that the calcium molecules are not distributed evenly across the length of each sarcomere; the molecules are released from the ends. Despite this, the sarcomeres contract uniformly. But exactly how has remained a thorny mystery.

C protein protein was known to exist in all heart muscle cells, but until now, its function was unknown. Using an animal model, the researchers studied the physiology of sarcomeres, measuring calcium release and the muscle fibers' mechanical reaction. It turns out that C protein sensitizes certain parts of the sarcomere to calcium. As a result, the middle of the sarcomere contracts just as much as the ends, despite having much less calcium. In other words, C protein enables the sarcomeres to contract synchronously.

"Calcium is like the sparkplugs in an automobile engine and C protein acts like the rings that increase the efficiency of the movement of the pistons," says Michael J. Previs, PhD, an assistant professor in the Department of Molecular Physiology and Biophysics at the University of Vermont.

C protein appears to play a large part in many forms of heart disease. In the most severe cases, defects in C-protein lead to extremely serious arrhythmias, which cause sudden death when the heart loses the ability to pump blood. In the United States, arrhythmias contribute to about 300,000 deaths a year, according to the American Heart Association. (Not all arrhythmias are fatal; some can be controlled with medicines and electrical stimulation.)

W. Jonathan Lederer, MD, PhD, professor of physiology at the University of Maryland School of Medicine, and his colleagues think that it may be possible to affect arrhythmias by modifying the activity of C protein through drugs. "I think this could be very big," Lederer says. "This protein is definitely a drug target."

[Source: University of Maryland School of Medicine]
About the Author
  • Judy O'Rourke worked as a newspaper reporter before becoming chief editor of Clinical Lab Products magazine. As a freelance writer today, she is interested in finding the story behind the latest developments in medicine and science, and in learning what lies ahead.
You May Also Like
JUN 19, 2018
Cardiology
JUN 19, 2018
Autopsies to Understand Heart Disease: What Went Wrong
Autopsies aren’t as common as they used to be, but scientists may have a reason for a comeback. A new series of studies from the American Heart Assoc...
JUN 23, 2018
Videos
JUN 23, 2018
In Search of Genetic Risk Factors for AFib
Researchers at Mass General have recently learned more about genetic factors that are contributing to a person's risk of developing AFib....
JUN 29, 2018
Cardiology
JUN 29, 2018
The Drug That's Best for Both Kidney Failure and Arrhythmia Patients
A specific drug is the best to prescribe to people with both an irregular heartbeat and kidney failure. This population of people is at a particularly high...
AUG 05, 2018
Cell & Molecular Biology
AUG 05, 2018
The Major Health Risks Posed by Cipro
In recent years, studies have shown that a once-popular class of antibiotics can have life-threatening side effects....
OCT 24, 2018
Cardiology
OCT 24, 2018
Red Meat Has Been Linked To Increased Risk Of Heart Disease
Researchers have long suspected that allergens can trigger immunological responses that might have an association with plaque buildup and arterial blockage...
NOV 07, 2018
Immunology
NOV 07, 2018
Is Your Brain Asking for High Blood Pressure?
Study finds that the brain is sending signals to the bone marrow to increase blood pressure....
Loading Comments...