Oxidised LDL internalisation by the LOX-1 scavenger receptor is dependent on a novel cytoplasmic motif and is regulated by dynamin-2.
The LOX-1 scavenger receptor recognises pro-atherogenic oxidised low-density lipoprotein (OxLDL) particles and is implicated in atherosclerotic plaque formation, but this mechanism is not well understood. Here we show evidence for a novel clathrin-independent and cytosolic-signal-dependent pathway that regulates LOX-1-mediated OxLDL internalisation. Cell surface labelling in the absence or presence of OxLDL ligand showed that LOX-1 is constitutively internalised from the plasma membrane and its half-life is not altered upon ligand binding and trafficking. We show that LOX-1-mediated OxLDL uptake is disrupted by overexpression of dominant-negative dynamin-2 but unaffected by CHC17 or mu2 (AP2) depletion. Site-directed mutagenesis revealed a conserved and novel cytoplasmic tripeptide motif (DDL) that regulates LOX-1-mediated endocytosis of OxLDL. Taken together, these findings indicate that LOX-1 is internalised by a clathrin-independent and dynamin-2-dependent pathway and is thus likely to mediate OxLDL trafficking in vascular tissues.
Murphy
Jane E
JE
Endothelial Cell Biology Unit, Leeds Institute of Genetics, Health & Therapeutics, University of Leeds, Clarendon Way, Leeds, LS2 9JT, UK.
Vohra
Ravinder S
RS
Dunn
Sarah
S
Holloway
Zoe G
ZG
Monaco
Anthony P
AP
Homer-Vanniasinkam
Shervanthi
S
Walker
John H
JH
Ponnambalam
Sreenivasan
S
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D034285:Dynamin II / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000235:genetics; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; D034285:Dynamin II