title: Arabidopsis ribosomal proteins control vacuole trafficking and developmental programs through the regulation of lipid metabolism.
abstract: The vacuole is the most prominent compartment in plant cells and is important for ion and protein storage. In our effort to search for key regulators in the plant vacuole sorting pathway, ribosomal large subunit 4 (rpl4d) was identified as a translational mutant defective in both vacuole trafficking and normal development. Polysome profiling of the rpl4d mutant showed reduction in polysome-bound mRNA compared with wild-type, but no significant change in the general mRNA distribution pattern. Ribsomal profiling data indicated that genes in the lipid metabolism pathways were translationally down-regulated in the rpl4d mutant. Live imaging studies by Nile red staining suggested that both polar and nonpolar lipid accumulation was reduced in meristem tissues of rpl4d mutants. Pharmacological evidence showed that sterol and sphingolipid biosynthetic inhibitors can phenocopy the defects of the rpl4d mutant, including an altered vacuole trafficking pattern. Genetic evidence from lipid biosynthetic mutants indicates that alteration in the metabolism of either sterol or sphingolipid biosynthesis resulted in vacuole trafficking defects, similar to the rpl4d mutant. Tissue-specific complementation with key enzymes from lipid biosynthesis pathways can partially rescue both vacuole trafficking and auxin-related developmental defects in the rpl4d mutant. These results indicate that lipid metabolism modulates auxin-mediated tissue differentiation and endomembrane trafficking pathways downstream of ribosomal protein function.
authors.affiliation: Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
authors.forename: Ruixi
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
authors.forename: Ruobai
authors.initials: R
authors.lastname: Sun
authors.affiliation: Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Hicks
authors.affiliation: Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521 natasha.raikhel@ucr.edu.
authors.forename: Natasha V
authors.initials: NV
authors.lastname: Raikhel
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005816:Genetic Complementation Test; D007210:Indoleacetic Acids / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects / Q000235:genetics; D008055:Lipids / Q000096:biosynthesis; D018519:Meristem / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D021382:Protein Sorting Signals; D021381:Protein Transport / Q000187:drug effects; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D008055:Lipids; D021382:Protein Sorting Signals; D012269:Ribosomal Proteins
keywords: auxin response; lipid metabolism; ribosomal mutants; vacuole trafficking