title: Sorting nexin 5 selectively regulates dorsal-ruffle-mediated macropinocytosis in primary macrophages.
abstract: The regulation of macropinocytosis, a specialised endocytosis pathway, is important for immune cell function. However, it is not known whether the biogenesis of macropinosomes involves one or more distinct pathways. We previously identified sorting nexin 5 (SNX5) as a regulator of macropinocytosis in macrophages. Here, we show that bone-marrow-derived macrophages from SNX5-knockout mice had a 60-70% reduction in macropinocytic uptake of dextran or ovalbumin, whereas phagocytosis and retrograde transport from the plasma membrane to the Golgi was unaffected. In contrast, deficiency of SNX5 had no effect on macropinocytosis or antigen presentation by dendritic cells. Activation of macrophages with CSF-1 resulted in a localisation of SNX5 to actin-rich ruffles in a manner dependent on receptor tyrosine kinases. SNX5-deficient macrophages showed a dramatic reduction in ruffling on the dorsal surface following CSF-1 receptor activation, whereas peripheral ruffling and cell migration were unaffected. We demonstrate that SNX5 is acting upstream of actin polymerisation following CSF-1 receptor activation. Overall, our findings reveal the important contribution of dorsal ruffing to receptor-activated macropinocytosis in primary macrophages and show that SNX5 selectively regulates macropinosomes derived from the dorsal ruffles.
authors.affiliation: The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Jet Phey
authors.initials: JP
authors.lastname: Lim
authors.affiliation: The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Prajakta
authors.initials: P
authors.lastname: Gosavi
authors.affiliation: The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Justine D
authors.initials: JD
authors.lastname: Mintern
authors.affiliation: The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Ross
authors.affiliation: The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia pgleeson@unimelb.edu.au.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gleeson
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000502:physiology*; D003713:Dendritic Cells / Q000166:cytology / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010873:Pinocytosis / Q000502:physiology*; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism; D058305:Sorting Nexins / Q000235:genetics / Q000378:metabolism*
chemical_list: C000604004:Csf1r protein, mouse; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; C533712:Snx5 protein, mouse; D058305:Sorting Nexins
keywords: Antigen processing; Dorsal ruffle; Endocytosis; Macropinocytosis; SNX5; Sorting nexin