Faulty cellular antennae may cause a heart valve disorder


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Cells with faulty antennae that cant get their signals straight may be behind a common heart valve disorder.

Newborn mice engineered to develop a flawed heart valve had stunted primary cilia in cells that help to form the valve during development, researchers report online May 22 in Science Translational Medicine.

The heart valve disorder, called mitral valve prolapse, “is characterized by significant abnormalities in the composition and organization” of valve tissue, says Joy Lincoln, a heart valve researcher at Nationwide Childrens Hospital in Columbus, Ohio. Those abnormalities compromise the valves structure and function. The new work hints that primary cilia play a role in this improper development, she says.

The condition, which affects about 2 percent of the U.S. population, causes the valve separating two heart chambers — the left atrium and the left ventricle — to not seal properly. Normally, when the left ventricle pumps oxygenated blood to the body, the valve closes tightly so blood doesnt backtrack into the atrium. But with mitral valve prolapse, parts of the valve bulge into the atrium, which can let blood through.

A leaky valve can produce a heart murmur, a “click” sound a doctor can hear with a stethoscope. Some people with the condition dont experience any symptoms, while others may have rapid heartbeats or discomfort in their chest. If there is a lot of leaking blood, the heart may develop an infection, blood clots may form and raise a persons risk of stroke or heart attack, or a persons heart may eventually fail. The only way to fix the valve is with surgery.

Primary cilia, solitary cellular antennae thought to be crucial for signaling between cells (SN: 11/3/12, p. 16), differ from motile cilia, which work as a group to move things along the respiratory or reproductive tracts, for example. Scientists previously thought primary cilia were no longer functional. The idea that primary cilia might be involved in the heart valves troubles sprung partly from the recognition that people with polycystic kidney disease develop mitral valve prolapse more often than those in the general population. The kidney disease is one of a number of rare diseases called ciliopathies, which have in common dysfunctional primary cilia.

Russell Norris, a cardiovascular biologist at the Medical University of South Carolina in Charleston, and colleagues identified a multigenerational family with an inherited form of mitral valve prolapse. The affected family members shared a mutated gene linked to primary cilia. This discovery provided the impetus for exploring a possible role for the ciliaRead More – Source