title: Intracellular lumen extension requires ERM-1-dependent apical membrane expansion and AQP-8-mediated flux.
abstract: Many unicellular tubes such as capillaries form lumens intracellularly, a process that is not well understood. Here we show that the cortical membrane organizer ERM-1 is required to expand the intracellular apical/lumenal membrane and its actin undercoat during single-cell Caenorhabditis elegans excretory canal morphogenesis. We characterize AQP-8, identified in an ERM-1-overexpression (ERM-1[++]) suppressor screen, as a canalicular aquaporin that interacts with ERM-1 in lumen extension in a mercury-sensitive manner, implicating water-channel activity. AQP-8 is transiently recruited to the lumen by ERM-1, co-localizing in peri-lumenal cuffs interspaced along expanding canals. An ERM-1[++]-mediated increase in the number of lumen-associated canaliculi is reversed by AQP-8 depletion. We propose that the ERM-1/AQP-8 interaction propels lumen extension by translumenal flux, suggesting a direct morphogenetic effect of water-channel-regulated fluid pressure.
authors: Department of Pediatrics, Massachusetts General Hospital, Boston, 02114, USA.
authors: Liakot A
authors: LA
authors: Khan
authors: Hongjie
authors: H
authors: Zhang
authors: Nessy
authors: N
authors: Abraham
authors: Lei
authors: L
authors: Sun
authors: John T
authors: JT
authors: Fleming
authors: Matthew
authors: M
authors: Buechner
authors: David H
authors: DH
authors: Hall
authors: Verena
authors: V
authors: Gobel
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002463:Cell Membrane Permeability; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D008627:Mercuric Chloride / Q000494:pharmacology; D009024:Morphogenesis; D009154:Mutation; D009997:Osmotic Pressure; D010641:Phenotype; D011485:Protein Binding; D021381:Protein Transport; D034622:RNA Interference; D013997:Time Factors; D014867:Water / Q000378:metabolism; D014882:Water-Electrolyte Balance
chemical_list: D020346:Aquaporins; D029742:Caenorhabditis elegans Proteins; D003598:Cytoskeletal Proteins; C488174:ERM-1 protein, C elegans; C108330:aquaporin 8; D014867:Water; D008627:Mercuric Chloride