title: Sterol carrier protein 2 regulates proximal tubule size in the Xenopus pronephric kidney by modulating lipid rafts.
abstract: The kidney is a homeostatic organ required for waste excretion and reabsorption of water, salts and other macromolecules. To this end, a complex series of developmental steps ensures the formation of a correctly patterned and properly proportioned organ. While previous studies have mainly focused on the individual signaling pathways, the formation of higher order receptor complexes in lipid rafts is an equally important aspect. These membrane platforms are characterized by differences in local lipid and protein compositions. Indeed, the cells in the Xenopus pronephric kidney were positive for the lipid raft markers ganglioside GM1 and Caveolin-1. To specifically interfere with lipid raft function in vivo, we focused on the Sterol Carrier Protein 2 (scp2), a multifunctional protein that is an important player in remodeling lipid raft composition. In Xenopus, scp2 mRNA was strongly expressed in differentiated epithelial structures of the pronephric kidney. Knockdown of scp2 did not interfere with the patterning of the kidney along its proximo-distal axis, but dramatically decreased the size of the kidney, in particular the proximal tubules. This phenotype was accompanied by a reduction of lipid rafts, but was independent of the peroxisomal or transcriptional activities of scp2. Finally, disrupting lipid micro-domains by inhibiting cholesterol synthesis using Mevinolin phenocopied the defects seen in scp2 morphants. Together these data underscore the importance for localized signaling platforms in the proper formation of the Xenopus kidney.
authors.affiliation: Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA; Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas-CCS, Av. Carlos Chagas Filho, 373 bloco F2 sala 15, Rio de Janeiro 21949-590, Brazil.
authors.forename: Débora M
authors.initials: DM
authors.lastname: Cerqueira
authors.affiliation: Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA.
authors.forename: Uyen
authors.initials: U
authors.lastname: Tran
authors.affiliation: Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Romaker
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas-CCS, Av. Carlos Chagas Filho, 373 bloco F2 sala 15, Rio de Janeiro 21949-590, Brazil.
authors.forename: José G
authors.initials: JG
authors.lastname: Abreu
authors.affiliation: Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA. Electronic address: wesselo@ccf.org.
authors.forename: Oliver
authors.initials: O
authors.lastname: Wessely
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology; D019521:Body Patterning / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000096:biosynthesis; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000196:embryology* / Q000502:physiology; D008148:Lovastatin / Q000494:pharmacology; D021962:Membrane Microdomains / Q000235:genetics* / Q000502:physiology; D060172:Morpholinos; D012333:RNA, Messenger / Q000096:biosynthesis; D014158:Transcription, Genetic; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D000924:Anticholesteremic Agents; D002352:Carrier Proteins; D060172:Morpholinos; D012333:RNA, Messenger; D029867:Xenopus Proteins; C072087:sterol carrier proteins; D002784:Cholesterol; D008148:Lovastatin
keywords: Cholesterol; Lipid rafts; Organ size control; Pronephros; Sterol carrier protein 2; Xenopus