A loss-of-function screen reveals SNX5 and SNX6 as potential components of the mammalian retromer

Thomas Wassmer, Naomi Attar, Miriam V. Bujny, Jacqueline Oakley, Colin J. Traer, Peter J. Cullen

Research output: Contribution to journalArticle

Abstract

The mammalian retromer is a multimeric protein complex involved in mediating endosome-to-trans-Golgi-network retrograde transport of the cation-independent mannose-6-phosphate receptor. The retromer is composed of two subcomplexes, one containing SNX1 and forming a membrane-bound coat, the other comprising VPS26, VPS29 and VPS35 and being cargo-selective. In yeast, an additional sorting nexin--Vps17p--is a component of the membrane bound coat. It remains unclear whether the mammalian retromer requires a functional equivalent of Vps17p. Here, we have used an RNAi loss-of-function screen to examine whether any of the other 30 mammalian sorting nexins are required for retromer-mediated endosome-to-trans-Golgi-network retrieval of the cation-independent mannose-6-phosphate receptor. Using this screen, we identified two proteins, SNX5 and SNX6, that, when suppressed, induced a phenotype similar to that observed upon suppression of known retromer components. Whereas SNX5 and SNX6 colocalised with SNX1 on early endosomes, in immunoprecipitation experiments only SNX6 appeared to exist in a complex with SNX1. Interestingly, suppression of SNX5 and/or SNX6 resulted in a significant loss of SNX1, an effect that seemed to result from post-translational regulation of the SNX1 level. Such data suggest that SNX1 and SNX6 exist in a stable, endosomally associated complex that is required for retromer-mediated retrieval of the cation-independent mannose-6-phosphate receptor. SNX5 and SNX6 may therefore constitute functional equivalents of Vps17p in mammals.
Original languageEnglish
Pages (from-to)45-54
Number of pages10
JournalJournal of Cell Science
Volume120
Issue number1
Early online date5 Dec 2006
DOIs
Publication statusPublished - 1 Jan 2007

Keywords

  • carrier proteins
  • endosomes
  • gene expression
  • genetic testing
  • green fluorescent proteins
  • HeLa cells
  • humans
  • immunoprecipitation
  • confocal microscopy
  • protein transport
  • RNA interference
  • sorting nexins
  • vesicular transport proteins
  • trans-Golgi network

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    Wassmer, T., Attar, N., Bujny, M. V., Oakley, J., Traer, C. J., & Cullen, P. J. (2007). A loss-of-function screen reveals SNX5 and SNX6 as potential components of the mammalian retromer. Journal of Cell Science, 120(1), 45-54. https://doi.org/10.1242/jcs.03302