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Fig. 4
Lurap1 interacts with Dvl and JNK in cellular polarisation. a Schematic representation of Lurap1 and Dvl proteins. b Co-immunoprecipitation shows physical interaction between Lurap1 and Dvl. c–e Cell transplantation procedure for the analysis of cell polarity and protrusive activity. Labelled donors and unlabelled recipient embryos have either the same genotype, or they are injected with identical mRNAs or morpholinos. f–q Polarised behaviours and protrusive activities of transplanted cells integrated in the notochord of recipient embryos. The cell membrane is labelled by mGFP and the nucleus is labelled by Histone2B-RFP. The experiments were performed using at least three independent offspring, and a total of at least 10 embryos were analysed in each condition. Representative images are shown, with the anterior region positioned on the top. f A bipolar and mediolaterally elongated WT cell with unidirectional filopodia. The bidirectional arrow indicates anterior (A) and posterior (P) axis. g Multipolar protrusive MZlurap1 mutant cells are less elongated, with lamellipodia and filopodia in all directions. h A Xdsh-overexpressing cell loses polarity and forms multiple lamellipodia that also extend filopodia in random directions. i A Xdd1-overexpressing cell becomes multipolar protrusive, with extensive filopodia in all directions. j Knockdown of dvl2 and dvl3a in WT cells blocks protrusive activity, and morphant cells take a round shape. k Overexpression of caJNK in a WT cell disrupts polarised cell behaviours and induces multiple filopodia in random directions. l Blockade of JNK signalling in WT cells results in loss of protrusive activity and cell polarity. m–o The mediolateral polarity and protrusive activity of MZlurap1 mutant cells are rescued by reducing Dvl dosage or JNK activity, but not by increasing JNK activity. p, q Reducing JNK activity in Xdsh-overexpressing or Xdd1-overexpressing cells restores mediolateral polarity, and prevents the formation of randomised lamellipodia and filopodia. Scale bar: f–q 20 µm