AP-1 and AP-3 facilitate lysosomal targeting of Batten disease protein CLN3 via its dileucine motif.
CLN3 is a transmembrane protein with a predominant localization in lysosomes in non-neuronal cells but is also found in endosomes and the synaptic region in neuronal cells. Mutations in the CLN3 gene result in juvenile neuronal ceroid lipofuscinosis or Batten disease, which currently is the most common cause of childhood dementia. We have recently reported that the lysosomal targeting of CLN3 is facilitated by two targeting motifs: a dileucine-type motif in a cytoplasmic loop domain and an unusual motif in the carboxyl-terminal cytoplasmic tail comprising a methionine and a glycine separated by nine amino acids (Kyttala, A., Ihrke, G., Vesa, J., Schell, M. J., and Luzio, J. P. (2004) Mol. Biol. Cell 15, 1313-1323). In the present study, we investigated the pathways and mechanisms of CLN3 sorting using biochemical binding assays and immunofluorescence methods. The dileucine motif of CLN3 bound both AP-1 and AP-3 in vitro, and expression of mutated CLN3 in AP-1- or AP-3-deficient mouse fibroblasts showed that both adaptor complexes are required for sequential sorting of CLN3 via this motif. Our data indicate the involvement of complex sorting machinery in the trafficking of CLN3 and emphasize the diversity of parallel and sequential sorting pathways in the trafficking of membrane proteins.
Kyttälä
Aija
A
National Public Health Institute, Department of Molecular Medicine, Biomedicum Helsinki, FIN-00290 Helsinki, Finland. aija.kyttala@ktl.fi
Yliannala
Kristiina
K
Schu
Peter
P
Jalanko
Anu
A
Luzio
J Paul
JP
D033963:Adaptor Protein Complex 3; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002966:Clathrin / Q000737:chemistry; D003513:Cycloheximide / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004705:Endocytosis; D005982:Glutathione Transferase / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000166:cytology; D007930:Leucine / Q000737:chemistry*; D008247:Lysosomes / Q000737:chemistry / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D018832:Molecular Chaperones / Q000737:chemistry*; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014168:Transferrin / Q000378:metabolism
D033963:Adaptor Protein Complex 3; C105199:CLN3 protein, human; D002966:Clathrin; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D011500:Protein Synthesis Inhibitors; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D014168:Transferrin; D003513:Cycloheximide; D008715:Methionine; D005982:Glutathione Transferase; D007930:Leucine; D005998:Glycine