In Situ Imaging in C. elegans Reveals Developmental Regulation of Microtubule Dynamics

Microtubules (MTs) are cytoskeletal polymers that undergo dynamic instability, the stochastic transition between growth and shrinkage phases. MT dynamics are required for diverse cellular processes and, while intrinsic to tubulin, are highly regulated. However, little is known about how MT dynamics facilitate or are regulated by tissue biogenesis and differentiation. We imaged MT dynamics in a smooth muscle-like lineage in intact developing Caenorhabditis elegans. All aspects of MT dynamics change significantly as stem-like precursors exit mitosis and, secondarily, as they differentiate. We found that suppression, but not enhancement, of dynamics perturbs differentiated muscle function in vivo. Distinct ensembles of MT-associated proteins are specifically required for tissue biogenesis versus tissue function. A CLASP family MT stabilizer and the depolymerizing kinesin MCAK are differentially required for MT dynamics in the precursor or differentiated cells, respectively. All of these multidimensional phenotypic comparisons were facilitated by a data display method called the diamond graph. [Display omitted] •MT dynamics can be followed throughout differentiation in situ•MT dynamics are regulated stepwise over the course of differentiation•Distinct MAPs are required for tissue biogenesis and tissue function•Selective MT dynamics are required in proliferative versus differentiated cells Lacroix et al. used live imaging to study MT dynamics in the smooth muscle-like SM lineage of intact C. elegans worms. All aspects of MT dynamics changed over the course of development and differentiation. A candidate RNAi screen of conserved MAPs reveals the molecular basis for these changes.