Faulty cell membrane repair causes heart disease

Jul 03, 2007

During vigorous exercise, heart muscle cells take a beating. In fact, some of those cells rupture, and if not for a repair process capable of resealing cell membranes, those cells would die and cause heart damage (cardiomyopathy).

Researchers at the University of Iowa Roy J. and Lucille A. Carver College of Medicine have discovered a specific repair mechanism in heart muscle and identified a protein called dysferlin that is critical for resealing heart muscle cell membranes.

The study, led by UI researcher and Howard Hughes Medical Institute investigator Kevin Campbell, Ph.D., also shows that loss of dysferlin causes cardiomyopathy in mice. Furthermore, heart damage in these mice is exaggerated by vigorous exercise or by inherent muscle weakness caused by a muscular dystrophy defect. The results are published in the July 1 issue of the Journal of Clinical Investigation.

Active tissues, like a beating heart or contracting muscle, need mechanisms to repair the inevitable cell membrane tears caused by physical stress and strain. In 2003, Campbell and his colleagues identified dysferlin as a key protein in this vital repair mechanism in skeletal muscle. In humans, dysferlin deficiency -- which leads to faulty muscle membrane repair -- causes three types of muscular dystrophy.

The new study expands knowledge of dysferlin function, showing that dysferlin-mediated membrane repair is also important in heart muscle cells and suggests that inadequate membrane repair can also lead to cardiomyopathy.

"If we could boost this repair mechanism, it might be possible to slow cardiac and skeletal muscle damage in muscular dystrophy patients," said Campbell who also holds the Roy J. Carver Biomedical Research Chair in Molecular Physiology and is head of the department and a UI professor of neurology.

The UI team initially found that young mice that lacked dysferlin showed no heart damage, which is consistent with what is seen in humans with dysferlin mutations. However, a case study describing late-onset cardiomyopathy in a Japanese patient with a dysferlin deficiency prompted the UI team to look at the mice as they aged.

They found that the mice started to develop cardiomyopathy at about one year of age (middle aged for a mouse). The team also found that exercise exaggerated the stress-induced injury in these mice, suggesting that inadequate membrane repair led to cardiomyopathy.

The research team also bred mice that lacked both dysferlin and the protein dystrophin, which is missing in patients with Duchenne muscular dystrophy. These "double knockout" mice had early onset cardiomyopathy, which was much more severe than in mice with either of the single mutations. The results suggest that dysferlin might provide some protection against heart damage in Duchenne patients, at least at a young age, by delaying the onset of cardiomyopathy.

"We hope these findings will stimulate clinicians to look at the cardiac health of muscular dystrophy patients and the overall muscle health of patients with cardiomyopathy," Campbell said.

Source: University of Iowa

Explore further: New compounds protect nervous system from the structural damage of MS

add to favorites email to friend print save as pdf

Related Stories

Google hits back at rivals with futuristic HQ plan

19 hours ago

Google unveiled plans Friday for a new campus headquarters integrating wildlife and sweeping waterways, aiming to make a big statement in Silicon Valley—which is already seeing ambitious projects from Apple ...

Recommended for you

Mystery of the reverse-wired eyeball solved

23 hours ago

From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

Neurons controlling appetite made from skin cells

23 hours ago

Researchers have for the first time successfully converted adult human skin cells into neurons of the type that regulate appetite, providing a patient-specific model for studying the neurophysiology of weight ...

Quality control for adult stem cell treatment

Feb 27, 2015

A team of European researchers has devised a strategy to ensure that adult epidermal stem cells are safe before they are used as treatments for patients. The approach involves a clonal strategy where stem cells are collected ...

User comments : 0

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.