Sorting nexin 17 regulates ApoER2 recycling and reelin signaling.
ApoER2 is a member of the low density-lipoprotein receptor (LDL-R) family. As a receptor for reelin, ApoER2 participates in neuronal migration during development as well as synaptic plasticity and survival in the adult brain. A previous yeast two-hybrid screen showed that ApoER2 is a binding partner of sorting nexin 17 (SNX17) - a cytosolic adaptor protein that regulates the trafficking of several membrane proteins in the endosomal pathway, including LRP1, P-selectin and integrins. However, no further studies have been performed to investigate the role of SNX17 in ApoER2 trafficking and function. In this study, we present evidence based on GST pull-down and inmunoprecipitation assays that the cytoplasmic NPxY endocytosis motif of ApoER2 interacts with the FERM domain of SNX17. SNX17 stimulates ApoER2 recycling in different cell lines including neurons without affecting its endocytic rate and also facilitates the transport of ApoER2 from the early endosomes to the recycling endosomes. The reduction of SNX17 was associated with accumulation of an ApoER2 carboxy-terminal fragment (CTF). In addition, in SNX17 knockdown cells, constitutive ApoER2 degradation was not modified, whereas reelin-induced ApoER2 degradation was increased, implying that SNX17 is a regulator of the receptor's half-life. Finally, in SNX17 silenced hippocampal and cortical neurons, we underscored a positive role of this endosomal protein in the development of the dendritic tree and reelin signaling. Overall, these results establish the role of SNX17 in ApoER2 trafficking and function and aid in identifying new links between endocytic trafficking and receptor signaling.
Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Millenium Nucleus for Renerative Biology (MINREB), Pontificia Universidad Católica de Chile, Santiago, Chile.
Pablo
P
Sotelo
Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Millenium Nucleus for Renerative Biology (MINREB), Pontificia Universidad Católica de Chile, Santiago, Chile.
Pamela
P
Farfán
Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Millenium Nucleus for Renerative Biology (MINREB), Pontificia Universidad Católica de Chile, Santiago, Chile.
María Luisa
ML
Benitez
Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, United States of America.
Guojun
G
Bu
Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Millenium Nucleus for Renerative Biology (MINREB), Pontificia Universidad Católica de Chile, Santiago, Chile.
María-Paz
MP
Marzolo
D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D004926:Escherichia coli; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005434:Flow Cytometry; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D026502:LDL-Receptor Related Proteins / Q000378:metabolism*; D016086:Lentivirus; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D051381:Rats; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D058305:Sorting Nexins / Q000378:metabolism*
D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D026502:LDL-Receptor Related Proteins; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; C000717129:Reln protein, rat; C487895:SNX17 protein, human; D058305:Sorting Nexins; C098773:low density lipoprotein receptor-related protein 8; D053829:Amyloid Precursor Protein Secretases; C000717127:RELN protein, human; D012697:Serine Endopeptidases