Fig. 3.

Zebrafish myomixer induces cell fusion. (A) Myomixer KO C2C12 cells infected with retroviruses expressing zebrafish myomixer, myomaker, or mouse myomaker were differentiated for 1 wk and stained with anti-myosin and Hoechst. Note that myomixer, but not myomaker, rescued the fusion defect in the myomixer KO cells. (B) Quantification of the fusion index in A, shown as the average number of nuclei in a myosin⁺ cell. For each genotype, the nuclei in myosin⁺ cells of seven 10× fields were counted. Error bars stand for SE of mean. (C) The 10T1/2-GFP fibroblasts were infected with retroviruses expressing zebrafish myomaker with or without zebrafish myomixer for 2 d to induce cell fusion. Note that cell fusion was induced when both myomaker and myomixer were expressed. (D) Proliferating C2C12 cells were infected with retroviruses expressing zebrafish myomaker with or without zebrafish myomixer for 2 d to induce cell fusion. Cells were stained with anti-laminin and Hoechst. Arrowheads indicate mononucleated cells; arrows indicate multinucleated cells. (Scale bars, 50 µm.)