Simulating tubulogenesis in the developing salivary gland

Laurent MacKay
Department of Mathematics
The University of British Columbia

Drosophila salivary glands serve as a simple model system for studying tubulogenesis. They start as roughly flat sheet of epithelial cells that deform into narrow invaginating tubes, exhibiting zero cell death or division throughout the process. A recent biophysical model of the salivary gland reproduced many key experimental findings and elucidated the contributions of the various myosin pools to the early invagination process. However, it treated cell-cell interfaces as a network of elastic springs, resulting in a relatively shallow and wide cone-shaped gland rather than tubular structure observed in-vivo. We incorporate stress-relaxation, an intrinsic property of the actin cytoskeleton, into the model by using viscoelastic elements. This modification greatly improves the overall shape of the gland. We quantify how stress-relaxation can facilitate topological transitions in the network of cell edges, a tissue-scale mechanism for enhancing deformation of the gland. Finally, we explore some putative effects of biochemical signalling that has been proposed to influence stress-relaxation, yielding insight into how different modes of stress relaxation changes the geometry of the salivary gland.