Fig. 1

DYRK1-mediated phosphorylation is required for Ciona notochord lumen expansion. A The timeline of notochord tubulogenesis. The region of green dashed box was magnified to illustrate the spherical-lumen shape and the diameter of the lumen. B Schematic representation of the wild-type and mutant DYRK1 constructs. Kinase-inactive mutants were constructed by substituting tyrosine with histidine in the activation loop or deleting the catalytic loop (residues 394–404). C Overexpression of DYRK1 mutants arrested lumen expansion. The white circle depicts the edge of the lumen, and the white asterisk indicates lumen with phenotype, and the red asterisk indicates control lumen. D The statistical analysis of lumen diameters. The “n” represents the number of lumens. Asterisks (***) represent statistical significance (p < 0.001). E Treatment with DYRK1 inhibitors (AZ191, 40 μM; Harmine, 40 μM; Mirk-IN-1, 160 μM) arrested lumen expansion. F The statistical analysis of lumen diameters. There was a significant difference in lumens diameter of control and the drug-treated groups. The “n” represents the number of lumens. Asterisks (***) represent statistical significance (p < 0.001). Scale bar 10 μm