The luminal domain participates in the endosomal trafficking of the cation-independent mannose 6-phosphate receptor.
Although the role of the cytoplasmic tail of the cation-independent mannose 6-phosphate receptor (CIMPR) has been well established in the receptor trafficking, that of the luminal domain is still controversial. We noticed that the peripheral distribution of GFP, fused to the transmembrane and cytoplasmic domains of CIMPR (G-CIMPR-tail), was distinct from that of endogenous CIMPR or of GFP fused to the full-length CIMPR (G-CIMPR-full). By live-cell imaging, trans-Golgi-network (TGN)-derived transport carriers containing G-CIMPR-full more frequently stopped and overlapped with transferrin-containing endosomes in the peripheral region than those containing G-CIMPR-tail. G-CIMPR-full was recycled back to the perinuclear TGN more slowly than that for G-CIMPR-tail, evidenced by fluorescence recovery after photobleaching analysis. Moreover, endogenous CIMPR and G-CIMPR-full, but not GFP-CIMPR-tail, drastically altered the characteristic distribution after treatment with chloroquine. A mutant receptor, G-CIMPR-full R/A, that cannot recognize the mannose 6-phosphate (M6P)-signal, behaved similarly to G-CIMPR-full, indicating that these differences are not attributable to the M6P-ligands binding situation. Interestingly, we also found that U18666A treatment was able to discriminate the M6P-ligand binding-dependent trafficking of CIMPR. Based on these findings, we propose that the CIMPR luminal domain is required for tight interaction with endocytic compartments, and retention by them, and that there are additional transport steps, in which the binding to M6P-ligands is involved.
Waguri
Satoshi
S
Department of Anatomy and Histology, Fukushima Medical University, School of Medicine, 1-Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan. waguri@fmu.ac.jp
Tomiyama
Yuji
Y
Ikeda
Hiroko
H
Hida
Tatsuhiro
T
Sakai
Norio
N
Taniike
Masako
M
Ebisu
Shigeyuki
S
Uchiyama
Yasuo
Y
D000736:Androstenes / Q000494:pharmacology; D000924:Anticholesteremic Agents / Q000494:pharmacology; D001665:Binding Sites; D002412:Cations / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism*; D002738:Chloroquine / Q000494:pharmacology; D011992:Endosomes / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D006367:HeLa Cells; D006801:Humans; D038761:Photobleaching; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017527:Receptor, IGF Type 2 / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D021601:trans-Golgi Network / Q000378:metabolism
D000736:Androstenes; D000924:Anticholesteremic Agents; D002412:Cations; D021382:Protein Sorting Signals; D017527:Receptor, IGF Type 2; C006261:3-beta-(2-(diethylamino)ethoxy)androst-5-en-17-one; D002738:Chloroquine