Microtubule dynamics direct heart cell growth

Heart muscle cells (cardiomyocytes) contract along their long axis to power the heartbeat. Maintaining that elongated shape is essential for efficient pumping. In heart failure, cells often become rounder, which reduces contractile efficiency. Understanding what controls the direction of cell growth matters for developing repair strategies.

The study, published in Science, shows that microtubules, the tubular protein structures that form a cell’s internal skeleton, control the direction in which cardiomyocytes grow. Microtubules are not static; they grow and shrink continuously. That dynamic behavior, the researchers found, does not just organise the cell’s interior. It actively steers the direction of cell elongation.

What goes wrong in heart disease

In heart failure, cardiomyocytes shift from an elongated to a rounder shape. This change reduces pumping efficiency. Earlier work had suggested that microtubules are reorganised differently in diseased hearts. The new study adds a causal mechanism: it is the growth movements of microtubules that set cell orientation. When that mechanism is disrupted, cells grow in the wrong direction.

The researchers were able to influence growth direction in laboratory conditions by targeting microtubule dynamics directly. Whether this translates into a therapeutic approach in living hearts remains to be established.

Relevance for aging hearts

With age, cardiomyocytes progressively lose their capacity to renew themselves and compensate for damage. Understanding how cell orientation is regulated opens a potential avenue for therapies that support cardiac function in older adults. Microtubule dynamics are an appealing target because they are already modifiable by existing drugs in other disease contexts. The basic biology is now considerably clearer than before.

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