title: Apicobasal domain identities of expanding tubular membranes depend on glycosphingolipid biosynthesis.
abstract: Metazoan internal organs are assembled from polarized tubular epithelia that must set aside an apical membrane domain as a lumenal surface. In a global Caenorhabditis elegans tubulogenesis screen, interference with several distinct fatty-acid-biosynthetic enzymes transformed a contiguous central intestinal lumen into multiple ectopic lumens. We show that multiple-lumen formation is caused by apicobasal polarity conversion, and demonstrate that in situ modulation of lipid biosynthesis is sufficient to reversibly switch apical domain identities on growing membranes of single post-mitotic cells, shifting lumen positions. Follow-on targeted lipid-biosynthesis pathway screens and functional genetic assays were designed to identify a putative single causative lipid species. They demonstrate that fatty-acid biosynthesis affects polarity through sphingolipid synthesis, and reveal ceramide glucosyltransferases (CGTs) as end-point biosynthetic enzymes in this pathway. Our findings identify glycosphingolipids, CGT products and obligate membrane lipids, as critical determinants of in vivo polarity and indicate that they sort new components to the expanding apical membrane.
authors.affiliation: Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Zhang
authors.forename: Nessy
authors.initials: N
authors.lastname: Abraham
authors.forename: Liakot A
authors.initials: LA
authors.lastname: Khan
authors.forename: David H
authors.initials: DH
authors.lastname: Hall
authors.forename: John T
authors.initials: JT
authors.lastname: Fleming
authors.forename: Verena
authors.initials: V
authors.lastname: Göbel
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D049108:Cell Enlargement; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D016764:Cell Polarity / Q000235:genetics; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D005838:Genotype; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006028:Glycosphingolipids / Q000096:biosynthesis*; D006900:Hydroxylation; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010641:Phenotype; D034622:RNA Interference; D051102:Serine C-Palmitoyltransferase / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D022161:Transport Vesicles / Q000378:metabolism; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D029742:Caenorhabditis elegans Proteins; D006028:Glycosphingolipids; D000429:Alcohol Oxidoreductases; C525834:LET-767 protein, C elegans; D051102:Serine C-Palmitoyltransferase; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase; D003066:Coenzyme A Ligases; D000098859:Long-Chain-Fatty-Acid-CoA Ligase; D000103:Acetyl-CoA Carboxylase