Abstract
The formation of an epithelial tube is a fundamental process for organogenesis. During Drosophila embryonic salivary gland (SG) invagination, Folded gastrulation (Fog)- dependent Rho-associated kinase (Rok) promotes contractile apical myosin formation to drive apical constriction. Microtubules (MTs) are also crucial for this process and are required for forming and maintaining apicomedial myosin. However, the underlying mechanism that coordinates actomyosin and MT networks still remains elusive. Here, we show that MT-dependent intracellular trafficking regulates apical constriction during SG invagination. Key components involved in protein trafficking, such as Rab11 and Nuclear fallout (Nuf), are apically enriched near the SG invagination pit in a MT-dependent manner. Disruption of the MT networks or knockdown of Rab11 impairs apicomedial myosin formation and apical constriction. We show that MTs and Rab11 are required for apical enrichment of the Fog ligand and the continuous distribution of the apical determinant protein Crumbs (Crb) and the key adherens junction protein E-Cadherin (E-Cad) along junctions. Targeted knockdown of crb or E-Cad in the SG disrupts apical myosin networks and results in apical constriction defects. Our data suggest a role of MT- and Rab11-dependent intracellular trafficking in regulating actomyosin networks and cell junctions, to coordinate cell behaviors during tubular organ formation.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Abbreviations: Crb, Crumbs; E-Cad, E-Cadherin; Dhc64C, Dynein heavy chain 64C; Fog, Folded gastrulation; GFP, green fluorescent protein; Klar, Klarsicht; MT, microtubule; Nuf, Nuclear fallout; Rok, Rho-associated kinase; SG, salivary gland; WT, wild type; YFP, yellow fluorescent protein.
New quantification for E-Cad signals has been added as Figure 6K. Quantification of apical areas of SG cells in spastin-overexpressing SGs has been added as Supplemental Figure S2, C-E. A few minor changes have been made in the text.