Filopodia facilitate contact between distant cells in a tissue to support several cell-signaling paradigms during development. Of particular interest is Notch-Delta signaling which regulates the organization of sensory bristles on the thorax of Drosophila melanogaster . The activation of Notch-Delta bonds is known to require mechanical tension, which can be supplied by endocytosis of Delta ligands when cells are in direct contact. However, little is known about how Notch activation occurs between distant cells connected by filopodia. Our recent experiments show that basal filopodia in the fly notum are dynamic and under mechanical tension driven by myosin II contraction. Thus, we hypothesize that the protrusion and retraction dynamics of interacting basal filopodia generates sufficient pulling force to activate Notch. A mathematical model of the dynamics of interacting filopodia is developed and validated to test this hypothesis.
Enumah et al. (Sun,) studied this question.