Keeping the balance between the muscle cells of the heart's atria and ventricles
Fill your bathtub 20 times over and that's roughly how much blood your heart pumps around your body in a single day. It's a demanding job that requires power and rhythm, specifically the pumping action of the four chambers of the heart: two ventricles and two atria. These chambers are made of cells called cardiomyocytes. Researchers investigate how cardiomyocytes are produced during development using zebrafish embryos. A series of signalling proteins, together known as the Hippo pathway, regulate cell numbers in different organs. This pathway includes the enzymes lats1 and lats2. Getting rid of lats1 and 2 in zebrafish embryos (pictured, right) increased the number of atrial cardiomyocytes (green) when compared to normal embryos (left), as revealed by fluorescence microscopy. The number of ventricular cardiomyocytes (magenta) was unchanged. Creating the pumping powerhouse that is the heart therefore needs Hippo signalling to keep atrial cardiomyocyte numbers in check.
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