title: Lack of CD2AP disrupts Glut4 trafficking and attenuates glucose uptake in podocytes.
abstract: The adapter protein CD2-associated protein (CD2AP) functions in various signaling and vesicle trafficking pathways, including endosomal sorting and/or trafficking and degradation pathways. Here, we investigated the role of CD2AP in insulin-dependent glucose transporter 4 (Glut4, also known as SLC2A4) trafficking and glucose uptake. Glucose uptake was attenuated in CD2AP(-/-) podocytes compared with wild-type podocytes in the basal state, and CD2AP(-/-) podocytes failed to increase glucose uptake in response to insulin. Live-cell imaging revealed dynamic trafficking of HA-Glut4-GFP in wild-type podocytes, whereas in CD2AP(-/-) podocytes, HA-Glut4-GFP clustered perinuclearly. In subcellular membrane fractionations, CD2AP co-fractionated with Glut4, IRAP (also known as LNPEP) and sortilin, constituents of Glut4 storage vesicles (GSVs). We further found that CD2AP forms a complex with GGA2, a clathrin adaptor, which sorts Glut4 to GSVs, suggesting a role for CD2AP in this process. We also found that CD2AP forms a complex with clathrin and connects clathrin to actin in the perinuclear region. Furthermore, clathrin recycling back to trans-Golgi membranes from the vesicular fraction containing GSVs was defective in the absence of CD2AP. This leads to reduced insulin-stimulated trafficking of GSVs and attenuated glucose uptake into CD2AP(-/-) podocytes.
authors.affiliation: Department of Pathology, University of Helsinki, 00290 Helsinki, Finland.
authors.forename: Tuomas A
authors.initials: TA
authors.lastname: Tolvanen
authors.affiliation: Department of Pathology, University of Helsinki, 00290 Helsinki, Finland.
authors.forename: Surjya Narayan
authors.initials: SN
authors.lastname: Dash
authors.affiliation: Department of Pathology, University of Helsinki, 00290 Helsinki, Finland.
authors.forename: Zydrune
authors.initials: Z
authors.lastname: Polianskyte-Prause
authors.affiliation: Department of Pathology, University of Helsinki, 00290 Helsinki, Finland.
authors.forename: Vincent
authors.initials: V
authors.lastname: Dumont
authors.affiliation: Department of Pathology, University of Helsinki, 00290 Helsinki, Finland sanna.h.lehtonen@helsinki.fi.
authors.forename: Sanna
authors.initials: S
authors.lastname: Lehtonen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002461:Cell Line, Transformed; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D010122:Cystinyl Aminopeptidase / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D050199:Podocytes / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D022161:Transport Vesicles / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C114545:CD2-associated protein; D002966:Clathrin; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C528734:GLUT4 enhancer factor, mouse; D014157:Transcription Factors; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; D005947:Glucose
keywords: Actin; Clathrin; GGA2; Glut4 trafficking